*e-mail: [email protected]
Effect of Heat Treatment on Some Mechanical Properties of 7075 Aluminium Alloy
Adeyemi Dayo Isadarea, Bolaji Aremob, Mosobalaje Oyebamiji Adeoyec,
Oluyemi John Olawalec*, Moshood Dehinde Shittuc
aPrototype Engineering Development Institute Ilesa, Nigeria
bCentre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Nigeria
cDepartment of Materials Science and Engineering, Obafemi Awolowo University, Ile-Ife, Nigeria
Received: April 14, 2012; Revised: September 3, 2012
This paper reports the effects of annealing and age hardening heat treatments on the microstructural
morphology and mechanical properties of 7075 Al alloy. The material was cast in the form of round
cylindrical rods inside green sand mould from where some samples were rapidly cooled by early
knockout and others gradually cooled to room temperature. From the samples that were gradually
cooled some were annealed while others were age hardened. Both the as-cast in each category and
heat treated samples were subjected to some mechanical tests and the morphology of the resulting
microstructures were characterised by optical microscopy. From the results obtained there is formation
of microsegregations of MgZn
2
during gradual solidification which was not present during rapid
cooling. It was also found out that age hardening and annealing heat treatment operation eliminated
these microsegregations and improve mechanical properties of 7075 Al alloy. It is concluded that
microsegregation can be eliminated by rapid solidification and appropriate heat treatment process.
Keywords: 7075 aluminium, microsegregation, precipitation hardening, annealing, magnesium alloy,
strength
1. Introduction
Aluminium and its alloys are used in a variety of cast and
wrought forms and conditions of heat treatment. For over
70 years, it ranks next to iron and steel in the metal market.
The demand for aluminium grows rapidly because of its
unique combination of properties which makes it becomes
one of the most versatile of engineering and construction
material1-3.
The optimum properties of aluminium are achieved by
alloying additions and heat treatments. This promotes the
formation of small hard precipitates which interfere with
the motion of dislocations and improve its mechanical
properties4-7. One of the most commonly used aluminium
alloy for structural applications is 7075 Al alloy due to its
attractive comprehensive properties such as low density, high
strength, ductility, toughness and resistance to fatigue8-11. It
has been extensively utilized in aircraft structural parts and
other highly stressed structural applications12-16.
But aluminium-zinc alloy as it is in 7075 Al alloy is
susceptible to embrittlement because of microsegregation
of MgZn
2
precipitates which may lead to catastrophic
failure of components produced from it17,18. The alloy is also
susceptibility to stress corrosion cracking19,20. This is .
Investigation on the Rate of Solidification and Mould Heating in the Casting ...IOSR Journals
Abstract: The quality of casting in the foundry can be measured by the rate at which solidification of the
molten metal takes place, which is consequent upon the rate the mould, is able to dissipate the heat of
solidification to the surroundings. The faster or slower the heat removal process during solidification the
structure of the grains formed by the casting is either finer of coarser. An experimental investigation was
carried out to compare the rate of solidification of commercially pure aluminium in metallic moulds. The rate at
which solidification occurred was compared with the rate at which the mould absorbed and dissipates heat. The
experiments conducted recorded the temperature fields at different casting location and that of the moulds
respectively. The results showed that there is a direct relation of the rate of heat absorption by the mould and
the rate of solidification in metallic moulds.
Keywords – Aluminium, casting, heat, mould, solidification, temperature.
Effect of artificial aging temper t6 on tensile properties of aluminum alloy ...FreddyTaebenu
Penjelasan mengenai efek dari proses artificial aging untuk melihat perilaku dari properti material paduan aluminium pada pengujian uji tarik, ditujukan untuk teman-teman yang mengambil bidang atau konsentrasi serupa dalam ilmu material engineering guna untuk menghasilkan produk dengan kualitas terbaik
Study of the Tribological behavior of as cast Al-4.2%Cu-Al2O3 compositeIOSR Journals
The research work is carried out on the study of tribological property of aluminium based metal matrix composite material, which is fabricated by using sol-gel technique. The composite material is prepared through liquid metallurgy method by using varying percentage of Alumina and aluminium and fixed percentage of copper 4.2%. Test sample billet is fabricated through casting method and has been examined the different mechanical behaviour such as Vickers Hardness Number, Ultimate Tensile Strength, 0.2% Proof Stress, etc.
From the study, it has been observed that with increase in the alumina content in matrix the ductility of composite show a contrary effect. The Pin-On-Disc test is used to evaluate the tribological property wear for composite material and it is observered that tendency of wear rate has improved. The weight losses of the specimen are measured and wear and friction characteristics are calculated with respect to time. Depth of wear track, sliding speed, bearing load friction coefficient and wear volume have been shown large sensitivity to the applied normal load and the testing time (or sliding distance). The XRD and SEM analysis are used to analyse the wear debris and track; and silent conclusion has been drawn
Investigation on the Rate of Solidification and Mould Heating in the Casting ...IOSR Journals
Abstract: The quality of casting in the foundry can be measured by the rate at which solidification of the
molten metal takes place, which is consequent upon the rate the mould, is able to dissipate the heat of
solidification to the surroundings. The faster or slower the heat removal process during solidification the
structure of the grains formed by the casting is either finer of coarser. An experimental investigation was
carried out to compare the rate of solidification of commercially pure aluminium in metallic moulds. The rate at
which solidification occurred was compared with the rate at which the mould absorbed and dissipates heat. The
experiments conducted recorded the temperature fields at different casting location and that of the moulds
respectively. The results showed that there is a direct relation of the rate of heat absorption by the mould and
the rate of solidification in metallic moulds.
Keywords – Aluminium, casting, heat, mould, solidification, temperature.
Effect of artificial aging temper t6 on tensile properties of aluminum alloy ...FreddyTaebenu
Penjelasan mengenai efek dari proses artificial aging untuk melihat perilaku dari properti material paduan aluminium pada pengujian uji tarik, ditujukan untuk teman-teman yang mengambil bidang atau konsentrasi serupa dalam ilmu material engineering guna untuk menghasilkan produk dengan kualitas terbaik
Study of the Tribological behavior of as cast Al-4.2%Cu-Al2O3 compositeIOSR Journals
The research work is carried out on the study of tribological property of aluminium based metal matrix composite material, which is fabricated by using sol-gel technique. The composite material is prepared through liquid metallurgy method by using varying percentage of Alumina and aluminium and fixed percentage of copper 4.2%. Test sample billet is fabricated through casting method and has been examined the different mechanical behaviour such as Vickers Hardness Number, Ultimate Tensile Strength, 0.2% Proof Stress, etc.
From the study, it has been observed that with increase in the alumina content in matrix the ductility of composite show a contrary effect. The Pin-On-Disc test is used to evaluate the tribological property wear for composite material and it is observered that tendency of wear rate has improved. The weight losses of the specimen are measured and wear and friction characteristics are calculated with respect to time. Depth of wear track, sliding speed, bearing load friction coefficient and wear volume have been shown large sensitivity to the applied normal load and the testing time (or sliding distance). The XRD and SEM analysis are used to analyse the wear debris and track; and silent conclusion has been drawn
Effects of Continuous Cooling On Impact and Micro Structural Properties of Lo...IJMER
Some mechanical properties and microstructural analysis were conducted on shielded
metal arc weldments of low carbon steels in some simulated environments. Specimens were prepared
and subjected to welding and continuous cooling at the same time at various positions. Results obtained
for impact strength using Charpy impact testing machine showed that impact strength of water cooled
samples were higher compared to salty water cooled samples. This is due to the increased formation of
martensitic structure and finer pearlite grains. The microstructure of the samples was studied using
photographic visual metallurgical microscope. For low cooling rate as in the air cooled sample, the
austenite was observed to transform into ferrite and pearlite. Ferrite is a body-centred cubic crystal
structure of iron alloys. For higher cooling rates of water and salt water cooled samples, low
temperature transformation products like bainite (an acicular microstructure which is not a phase) or
martensite (a very hard form of steel crystalline structure) were formed. The salt water cooled samples
had more martensite regions because of the increased cooling rate
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
EFFECT OF SILICON OXIDE (SIO2) REINFORCED PARTICLES ON AGEING BEHAVIOR OF Al-...IAEME Publication
Al-2024 alloy can be reinforced with different percentages of Silicon oxide particles using a stir casting method. The solution treatment of the composite sample and the unreinforced alloy was carried out at 550 ᴼC for 2h followed by aging at 150 ᴼC for various aging times between 1h and 5 hrs. The existence of SiO2 particles led to increasing the peak hardness of the alloy. The results revealed that peak hardness of the composite sample took place at shorter times than that of the unreinforced alloy for the samples solution treated for 2 h for both the composite and the unreinforced alloy that led to the fastest aging kinetics and the maximum hardness.
Comparison of Mechanical Properties of Austempered, Normalized and As-Weld Ca...IJAEMSJORNAL
More often than not, welded joints experience failure such as fracture which jeopardize their reliability and ergonomics when put in perspective. Attempting a significant improvement in the mechanical properties of welded joint through heat treatment could ensure joints stability and reduce the costs associated with constant repairs and replacements. In this study, the effects of heat treatments (austempering and normalization) on the mechanical properties of weldments were examined. The locally recycled steel sample was sourced from the Delta Steel Company Aladja, Delta State and the spectro-analysis was carried out on it. The test samples were machined as per properties for tests, fractured locally and were welded using shielded metal arc welding (SMAW) with stainless steel electrode. They were then heat treated in electric furnaces. The mechanical properties (tensile strength, yield strength, hardness and impact toughness) were determined and the microstructure examined using scanning electron microscope. They were also examined physically using hand lens. The result indicated that the austempered samples improved significantly in terms of its tensile strength, yield strength, hardness and ductility. It was also found that the untreated sample produced the greatest impact toughness. The result of the physical examination also suggested that heat treatment using oil based quenchant have the potential to inhibit rust at weld joints.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
THE EFFECT OF HEAT TREATMENT PARAMETERS AND GRAIN REFINEMENT ON MICROSTRUCTUR...dbpublications
Aluminium A357 alloy is widely used
at automobile and aircraft industries in the form of
cast component with varying section size. This study
investigates how the microstructure and mechanical
properties of A357 alloy before and after heat
treatment processes. Solutionising at 5000C-5h
followed quenching in water at room temperature
and Ageing at 1700C-3h alloy. Aluminium ingot is
melted using a furnace and poured in to the mold
having mold cavities of varying dimensions. In
order to investigate the effect of heat treatment and
aging processes microstructure and mechanical
properties such as hardness, and tensile strength
were analyzed as-cast condition and after solution
treatment process. The aim of present study is to
evaluate the effect on the microstructure and
mechanical properties of Combined Grain Refined
and Modified aluminum alloy A357
Microstructure and Hardness of Aluminium Alloy- Fused Silica Particulate Comp...AM Publications
Aluminum matrix composites (AMCs) refer to the class of light weight high performance aluminum centric
material systems. The reinforcement in AMCs could be in the form of continuous/discontinuous fibers, whiskers or particulates,
in volume fractions. Properties of AMCs can be tailored to the demands of different industrial applications by suitable
combinations of matrix, reinforcement and processing route. This work focuses on the fabrication of aluminum alloy (LM13)
matrix composites reinforced with 9%, 12% &15% fused silica particulates using stir casting route. The microstructure and
hardness of the fabricated composite were analyzed and reported.
A study on characterization of Al-18%Si alloy by centrifuge castingdbpublications
Aluminum-silicon alloy are characterized by light weight, good strength –to-weight ratio, ease of fabrication of at reasonable cost, high strength at elevated temperature, good thermal conductivity, excellent castability, good weldability, excellent corrosion and wear resistance property. Thus, these types of alloys are well suited for automotive industries, aerospace structural and military applications. In centrifuge casting solidification rate is faster compared to gravity casting, but still solidification depends on various process parameters like, cooling temperature of molten metal, rotational speed of the die and also wall thickness of die. In centrifuge casting the silicon deposition in aluminum varies from top to bottom. Here Al-Si functionally graded material is used and developed under centrifuge casting. The method used in this work to produce functionally graded material is totally different from other centrifugal casting which helped in producing solid cylindrical parts. This report describes about mechanical characterization of Al-18%Si at different temperature. At 950°C casting shows good ultimate tensile strength and harder metal compared to other casting.
The effect of Deep cryogenic treatment (DCT) on the metallurgical and mechani...Dr.M BALA THEJA
The effect of Deep cryogenic treatment (DCT) on the metallurgical and mechanical properties of Aluminium 6061-T6 is investigated in the present work
The test castings were solutionized at 525°C for 08 hrs and water quenched to room temperature. One set of samples were subjected to cryogenic treatment at -196°C in Cryo- treatment unit, while the other set is subjected to age hardening at 160°C for durations of 3 hrs, 5hrs and 7hrs. Again cryogenic treated specimens were subjected to age hardening at 165°C for durations of 3hrs, 5 hrs and 7hrs. All the samples were taken for Mechanical properties evaluation.
The total duration of the Cryogenic treatment cycle was 36 hrs, which includes 3hrs of cooling from room temperature to -196°C, 24hrs of holding and 09 hrs of warming to room temperature. The Cryogenic treatment was carried out in a specially designed Cryogenic unit
EFFECT OF SCANDIUM ON THE SOFTENING BEHAVIOUR OF DIFFERENT DEGREE OF COLD ROL...msejjournal
The softening behavior of different cold rolled Al-6Mg alloys containing scandium 0.2 wt% and 0.6 wt% have been investigated by means of microscopy, hardness and electrical conductivity measurements. It is found that the scandium added alloys attend the higher hardness at every state of cold rolling at higher
annealed temperature due to the precipitation of scandium aluminides. Electrical resistivity of the scandium added alloys show higher than base alloy due to grain refining. It is seen from the microstructure that scandium refine the grain structure and inhibit recrystallization.
Effect of Scandium on the Softening Behaviour of Different Degree of Cold Rol...msejjournal
The softening behavior of different cold rolled Al-6Mg alloys containing scandium 0.2 wt% and 0.6 wt% have been investigated by means of microscopy, hardness and electrical conductivity measurements. It is found that the scandium added alloys attend the higher hardness at every state of cold rolling at higher annealed temperature due to the precipitation of scandium aluminides. Electrical resistivity of the scandium added alloys show higher than base alloy due to grain refining. It is seen from the microstructure that scandium refine the grain structure and inhibit recrystallization.
Each group will write a research paper on an organization of their.docxkanepbyrne80830
Each group will write a research paper on an organization of their choice 10-12 pages minimum (not including title and reference sheet). The organizational analysis will utilize a minimum of 10-12 external, peer-reviewed academic sources and contain the following sections
:
Topic:
How do you determine whether an organization is ethical or not?
(250 -300 WORDS MINIMUM)
Groups can add more ethical information about their chosen company to substantiate your paper.
List of companies( My topic should be related to facebook)
Dell
Google
Amazon
Apple
Facebook
Ford
Tesla
SouthWest Airlines
Capitol One
Uber
.
E-Poster The students will complete an E-Poster, The purpose of th.docxkanepbyrne80830
E-Poster: The students will complete an E-Poster, The purpose of the poster is to serve as a summary and an advertisement of the work that supplements the researcher's presentation. The poster could be thought of as an illustrated version of the abstract with visual displays of data and small blocks of text that explain the project and support the data. Base on Chapters 2.
.
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Effects of Continuous Cooling On Impact and Micro Structural Properties of Lo...IJMER
Some mechanical properties and microstructural analysis were conducted on shielded
metal arc weldments of low carbon steels in some simulated environments. Specimens were prepared
and subjected to welding and continuous cooling at the same time at various positions. Results obtained
for impact strength using Charpy impact testing machine showed that impact strength of water cooled
samples were higher compared to salty water cooled samples. This is due to the increased formation of
martensitic structure and finer pearlite grains. The microstructure of the samples was studied using
photographic visual metallurgical microscope. For low cooling rate as in the air cooled sample, the
austenite was observed to transform into ferrite and pearlite. Ferrite is a body-centred cubic crystal
structure of iron alloys. For higher cooling rates of water and salt water cooled samples, low
temperature transformation products like bainite (an acicular microstructure which is not a phase) or
martensite (a very hard form of steel crystalline structure) were formed. The salt water cooled samples
had more martensite regions because of the increased cooling rate
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
EFFECT OF SILICON OXIDE (SIO2) REINFORCED PARTICLES ON AGEING BEHAVIOR OF Al-...IAEME Publication
Al-2024 alloy can be reinforced with different percentages of Silicon oxide particles using a stir casting method. The solution treatment of the composite sample and the unreinforced alloy was carried out at 550 ᴼC for 2h followed by aging at 150 ᴼC for various aging times between 1h and 5 hrs. The existence of SiO2 particles led to increasing the peak hardness of the alloy. The results revealed that peak hardness of the composite sample took place at shorter times than that of the unreinforced alloy for the samples solution treated for 2 h for both the composite and the unreinforced alloy that led to the fastest aging kinetics and the maximum hardness.
Comparison of Mechanical Properties of Austempered, Normalized and As-Weld Ca...IJAEMSJORNAL
More often than not, welded joints experience failure such as fracture which jeopardize their reliability and ergonomics when put in perspective. Attempting a significant improvement in the mechanical properties of welded joint through heat treatment could ensure joints stability and reduce the costs associated with constant repairs and replacements. In this study, the effects of heat treatments (austempering and normalization) on the mechanical properties of weldments were examined. The locally recycled steel sample was sourced from the Delta Steel Company Aladja, Delta State and the spectro-analysis was carried out on it. The test samples were machined as per properties for tests, fractured locally and were welded using shielded metal arc welding (SMAW) with stainless steel electrode. They were then heat treated in electric furnaces. The mechanical properties (tensile strength, yield strength, hardness and impact toughness) were determined and the microstructure examined using scanning electron microscope. They were also examined physically using hand lens. The result indicated that the austempered samples improved significantly in terms of its tensile strength, yield strength, hardness and ductility. It was also found that the untreated sample produced the greatest impact toughness. The result of the physical examination also suggested that heat treatment using oil based quenchant have the potential to inhibit rust at weld joints.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
THE EFFECT OF HEAT TREATMENT PARAMETERS AND GRAIN REFINEMENT ON MICROSTRUCTUR...dbpublications
Aluminium A357 alloy is widely used
at automobile and aircraft industries in the form of
cast component with varying section size. This study
investigates how the microstructure and mechanical
properties of A357 alloy before and after heat
treatment processes. Solutionising at 5000C-5h
followed quenching in water at room temperature
and Ageing at 1700C-3h alloy. Aluminium ingot is
melted using a furnace and poured in to the mold
having mold cavities of varying dimensions. In
order to investigate the effect of heat treatment and
aging processes microstructure and mechanical
properties such as hardness, and tensile strength
were analyzed as-cast condition and after solution
treatment process. The aim of present study is to
evaluate the effect on the microstructure and
mechanical properties of Combined Grain Refined
and Modified aluminum alloy A357
Microstructure and Hardness of Aluminium Alloy- Fused Silica Particulate Comp...AM Publications
Aluminum matrix composites (AMCs) refer to the class of light weight high performance aluminum centric
material systems. The reinforcement in AMCs could be in the form of continuous/discontinuous fibers, whiskers or particulates,
in volume fractions. Properties of AMCs can be tailored to the demands of different industrial applications by suitable
combinations of matrix, reinforcement and processing route. This work focuses on the fabrication of aluminum alloy (LM13)
matrix composites reinforced with 9%, 12% &15% fused silica particulates using stir casting route. The microstructure and
hardness of the fabricated composite were analyzed and reported.
A study on characterization of Al-18%Si alloy by centrifuge castingdbpublications
Aluminum-silicon alloy are characterized by light weight, good strength –to-weight ratio, ease of fabrication of at reasonable cost, high strength at elevated temperature, good thermal conductivity, excellent castability, good weldability, excellent corrosion and wear resistance property. Thus, these types of alloys are well suited for automotive industries, aerospace structural and military applications. In centrifuge casting solidification rate is faster compared to gravity casting, but still solidification depends on various process parameters like, cooling temperature of molten metal, rotational speed of the die and also wall thickness of die. In centrifuge casting the silicon deposition in aluminum varies from top to bottom. Here Al-Si functionally graded material is used and developed under centrifuge casting. The method used in this work to produce functionally graded material is totally different from other centrifugal casting which helped in producing solid cylindrical parts. This report describes about mechanical characterization of Al-18%Si at different temperature. At 950°C casting shows good ultimate tensile strength and harder metal compared to other casting.
The effect of Deep cryogenic treatment (DCT) on the metallurgical and mechani...Dr.M BALA THEJA
The effect of Deep cryogenic treatment (DCT) on the metallurgical and mechanical properties of Aluminium 6061-T6 is investigated in the present work
The test castings were solutionized at 525°C for 08 hrs and water quenched to room temperature. One set of samples were subjected to cryogenic treatment at -196°C in Cryo- treatment unit, while the other set is subjected to age hardening at 160°C for durations of 3 hrs, 5hrs and 7hrs. Again cryogenic treated specimens were subjected to age hardening at 165°C for durations of 3hrs, 5 hrs and 7hrs. All the samples were taken for Mechanical properties evaluation.
The total duration of the Cryogenic treatment cycle was 36 hrs, which includes 3hrs of cooling from room temperature to -196°C, 24hrs of holding and 09 hrs of warming to room temperature. The Cryogenic treatment was carried out in a specially designed Cryogenic unit
EFFECT OF SCANDIUM ON THE SOFTENING BEHAVIOUR OF DIFFERENT DEGREE OF COLD ROL...msejjournal
The softening behavior of different cold rolled Al-6Mg alloys containing scandium 0.2 wt% and 0.6 wt% have been investigated by means of microscopy, hardness and electrical conductivity measurements. It is found that the scandium added alloys attend the higher hardness at every state of cold rolling at higher
annealed temperature due to the precipitation of scandium aluminides. Electrical resistivity of the scandium added alloys show higher than base alloy due to grain refining. It is seen from the microstructure that scandium refine the grain structure and inhibit recrystallization.
Effect of Scandium on the Softening Behaviour of Different Degree of Cold Rol...msejjournal
The softening behavior of different cold rolled Al-6Mg alloys containing scandium 0.2 wt% and 0.6 wt% have been investigated by means of microscopy, hardness and electrical conductivity measurements. It is found that the scandium added alloys attend the higher hardness at every state of cold rolling at higher annealed temperature due to the precipitation of scandium aluminides. Electrical resistivity of the scandium added alloys show higher than base alloy due to grain refining. It is seen from the microstructure that scandium refine the grain structure and inhibit recrystallization.
Each group will write a research paper on an organization of their.docxkanepbyrne80830
Each group will write a research paper on an organization of their choice 10-12 pages minimum (not including title and reference sheet). The organizational analysis will utilize a minimum of 10-12 external, peer-reviewed academic sources and contain the following sections
:
Topic:
How do you determine whether an organization is ethical or not?
(250 -300 WORDS MINIMUM)
Groups can add more ethical information about their chosen company to substantiate your paper.
List of companies( My topic should be related to facebook)
Dell
Google
Amazon
Apple
Facebook
Ford
Tesla
SouthWest Airlines
Capitol One
Uber
.
E-Poster The students will complete an E-Poster, The purpose of th.docxkanepbyrne80830
E-Poster: The students will complete an E-Poster, The purpose of the poster is to serve as a summary and an advertisement of the work that supplements the researcher's presentation. The poster could be thought of as an illustrated version of the abstract with visual displays of data and small blocks of text that explain the project and support the data. Base on Chapters 2.
.
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Q1: With this detail in mind,
briefly
state why the e-Mail has become a critical component for IG implementation?
.
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Dysfunctional Behaviors and Related Facilitation Strategies: Twelve Angry Men
Behavior
Actor/Evidence
Strategy Used or Suggested
Whisperer—periodically engages team member(s) in side conversations
Silent member—withdrawn; doesn’t participate
“Eager beaver” (talker/ monopolizer)—always has something to say
Heckler/complainer— combative; tells team members why what they’re working on will never work
Sidetracker—dicusses items not on the agenda
Fighter—picks a “fight” and/or argues with another team member
“Stand pat”—won’t budge; hostile; unwilling to look at situation from others’ perspective; often prejudiced
Verbal stumbler—unable to express self clearly
Early leaver—announces they must leave for another activity
Five Stages of Negotiating
All negotiations are different. Simple negotiations, such as choosing which movie to rent, need not require an extensive negotiation process. However, when negotiations involve significant or complex issues, you should consider using the five-stage process model
Negotiating consists of five stages: (1) preparation and planning, (2) defining ground rules, (3) clarifying and justifying your case, (4) bargaining and problem solving, and (5) closure and implementation.
These stages are described below. 1. Preparation and planning. Without question, preparation and planning are the keys to successful deal making. While some may think they can negotiate effectively “on the fly,” all negotiators benefit from thorough advance thought and preparation. Be clear about what you want and why. Gather data to support your position. Consider ways to present your arguments persuasively. Consider what the other party wants and why.
2. Definition of ground rules. Determining your own guidelines or rules for the negotiation helps you plan a strategy that can be successful. Establish who will or should be present and at what part of the negotiation. Decide where the meeting will be held and offer a possible agenda for how the time will be allocated and for which issues. The location has implications in terms of who’s in charge. While there may be a benefit to having the negotiation at your office—the home court advantage—agreeing to have the negotiation at the other party’s office might show flexibility and willingness to negotiate on your part. When the topic covered is potentially divisive or difficult, a neutral location might help level the playing field for both parties—an important consideration when an integrative solution is desired.
3. Clarification and justification. As the negotiation begins, state what you want and why. A key issue here is the difference between positions and interests. A position is a stance—typically a firm one—taken by a negotiator. “I’ll give you $4,500 and that’s my final offer.” An interest is the explanation behind the position, need, or desire that expresses why a negotiator wants what he or she wants. “I’m asking for $5,000 because the car has low miles, an u.
Dylan Rodríguez ends his essay with the following questionsHo.docxkanepbyrne80830
Dylan Rodríguez ends his essay with the following questions:
How has the state-structured influx of Asian and Pacific Rim migrant populations, and the subsequent emergence of contemporary Asian American communities, helped to further displace criminalized Black and Brown populations and amplify what Marable calls the ‘‘subtle apocalypse’’ of mass-based civic death?
How might the 1965 Immigration Act be re-narrated such that it is understood less as an ambivalent emblem of opportunity, liberal democracy, and freedom, and more as a fundamental facet of an American movement toward new forms of mass-based captivity and bodily immobilization, that is, as the harbinger of new forms of ‘‘unfreedom’’ as primary modes of social organization under the logic of white supremacist global capital?
Will it be possible to muster the intellectual creativity and political will to articulate a rupturing critique of the field’s operative structural, political, and theoretical assumptions, in order to develop a radical critique of the prison industrial complex that may fundamentally alter Asian American Studies (and Ethnic Studies) as attempted practices of social transformation?
Choose one of these questions, and give a preliminary answer. Do not worry if your answer is incomplete. It will be. That is fine. Do your best.
.
E D U C AT I O NStudy Theology, Even If You Dont Believe .docxkanepbyrne80830
E D U C AT I O N
Study Theology, Even If You Don't Believe in
God
The Evangelist St. Matthew with his symbol, the angel (THE NATIONAL LIBRARY OF THE NETHERLANDS / WIKIMEDIA
COMMONS)
When I first told my mother—a liberal, secular New Yorker—that I wanted to cross
an ocean to study for a bachelor’s degree in theology, she was equal parts aghast
and concerned. Was I going to become a nun, she asked in horror, or else one of
“those” wingnuts who picketed outside abortion clinics? Was I going to spend
hours in the Bodleian Library agonizing over the number of angels that could fit on
the head of a pin? Theology, she insisted, was a subject by the devout, for the
devout; it had no place in a typical liberal arts education.
Her view of the study of theology is far from uncommon. While elite universities
like Harvard and Yale offer vocational courses at their divinity schools, and nearly
all universities offer undergraduate majors in the comparative study of religions,
few schools (with the exceptions of historically Catholic institutions like
This lost liberal art encourages scholars to understand history from the inside
out.
TA R A I SA B E L L A B U RTO N OCT 30, 2013
https://www.theatlantic.com/education/
https://www.theatlantic.com/author/tara-isabella-burton/
Georgetown and Boston College) offer theology as a major, let alone mandate
courses in theology alongside other “core” liberal arts subjects like English or
history. Indeed, the study of theology has often run afoul of the legal separation of
church and state. Thirty-seven U.S. states have laws limiting the spending of public
funds on religious training. In 2006, the Supreme Court case Locke v. Davey upheld
the decision of a Washington State scholarship program to withhold promised
funding from an otherwise qualified student after learning that he had decided to
major in theology at a local Bible College.
Even in the United Kingdom, where secular bachelor's programs in theology are
more common, prominent New Atheists like Richard Dawkins have questioned
their validity in the university sphere. In a 2007 letter to the editor of The
Independent, Dawkins argues for the abolishment of theology in academia,
insisting that “a positive case now needs to be made that [theology] has any real
content at all, or that it has any place whatsoever in today's university culture.”
Such a shift, of course, is relatively recent in the history of secondary education.
Several of the great Medieval universities, among them Oxford, Bologna, and
Paris, developed in large part as training grounds for men of the Church. Theology,
far from being anathema to the academic life, was indeed its central purpose: It
was the “Queen of the Sciences” the field of inquiry which gave meaning to all
others. So, too, several of the great American universities. Harvard, Yale, and
Princeton alike were founded with the express purpose of teaching theology—one
early anonymous account of Harvard's founding speaks of Joh.
E V I D E N C E S Y N T H E S I SModels of care in nursing.docxkanepbyrne80830
E V I D E N C E S Y N T H E S I S
Models of care in nursing: a systematic reviewjbr_287 324..337
Ritin Fernandez RN MN (Critical Care) PhD,1,2 Maree Johnson RN BAppSci MAppSci PhD,3,4
Duong Thuy Tran BMed (Vietnam) MIPH (USyd)5 and Charmaine Miranda BPsycholgy6
1School of Nursing, Midwifery and Indigenous Health, University of Wollongong, Wollongong, 2Centre for Research in Nursing and
Health, St George Hospital, Kogarah, 3Centre for Applied Nursing Research, Sydney South West Area Health Service, 4School of Nursing
and Midwifery, University of Western Sydney, Sydney, 5School of Medicine, University of Western Sydney, Sydney, and 6Centre for Positive
Psychology and Education, School of Education, University of Western Sydney, Sydney, New South Wales, Australia
Abstract
Objective This review investigated the effect of the various models of nursing care delivery using the diverse levels
of nurses on patient and nursing outcomes.
Methods All published studies that investigated patient and nursing outcomes were considered. Studies were
included if the nursing delivery models only included nurses with varying skill levels. A literature search was
performed using the following databases: Medline (1985–2011), CINAHL (1985–2011), EMBASE (1985 to current)
and the Cochrane Controlled Studies Register (Issue 3, 2011 of Cochrane Library). In addition, the reference lists of
relevant studies and conference proceedings were also scrutinised. Two reviewers independently assessed the
eligibility of the studies for inclusion in the review, the methodological quality and extracted details of eligible studies.
Data were analysed using the RevMan software (Nordic Cochrane Centre, Copenhagen, Denmark).
Results Fourteen studies were included in this review. The results reveal that implementation of the team nursing
model of care resulted in significantly decreased incidence of medication errors and adverse intravenous outcomes,
as well as lower pain scores among patients; however, there was no effect of this model of care on the incidence of
falls. Wards that used a hybrid model demonstrated significant improvement in quality of patient care, but no
difference in incidence of pressure areas or infection rates. There were no significant differences in nursing outcomes
relating to role clarity, job satisfaction and nurse absenteeism rates between any of the models of care.
Conclusions Based on the available evidence, a predominance of team nursing within the comparisons is
suggestive of its popularity. Patient outcomes, nurse satisfaction, absenteeism and role clarity/confusion did not differ
across model comparisons. Little benefit was found within primary nursing comparisons and the cost effectiveness
of team nursing over other models remains debatable. Nonetheless, team nursing does present a better model for
inexperienced staff to develop, a key aspect in units where skill mix or experience is diverse.
Key words: evidence-based practice, nursing, systemat.
DuringWeek 5, we studied social stratification and how it influe.docxkanepbyrne80830
During
Week 5, we studied social stratification and how it influences what goes on in many social interactions among people. After you have read the reading assignment and lecture for this week, please respond to all parts of the discussion by the due date assigned:
What are some of the factors that affect social mobility? Can these be overcome?
Do you believe the structural-functionalist or the social conflict approach best explains social stratification? Why?
How does the media reflect attitudes on gender as far as depicting women and men in very traditional roles? Provide two detailed examples that substantiate your points—these can be an advertisement, television show, website, or magazine.
When you think of various groups (race, class, and gender) in society, which ones have the most power and which ones have the least? Using Intersection Theory, identify two groups that have unequal amounts of power and resources, being specific and using the text and outside resources. For each group, has the power dynamic changed over time? Do you think it will change in the future? Why or why not?
.
During Week Two the focus is on strategic leadership and managing th.docxkanepbyrne80830
During Week Two the focus is on strategic leadership and managing the strategy process. Use the concepts from Chapter 2 to respond to the discussion question below.
1) Post your initial respond to the discussion question by January 27, 2021.
Discussion question:
Read the Facebook scenario (ChapterCase 2) at the end of Chapter 2. Discuss whether the CEO and COO of Facebook are effective strategic leaders. Why or why not? What implications might this have on stakeholders?
Your response to the discussion question should be at least 250 words in length and contain at least one citation (not Wikipedia or dictionaries) from the course textbook, supplemental reading or video sources, or peer reviewed sources using the ADP library or Google (ADP Library, Google Scholar). Citations of 40 or more words are not acceptable as they represent a significant amount of an author's thoughts and/or perspectives rather than your own originality.
.
During Week 2, much focus is placed on various strategic thinking mo.docxkanepbyrne80830
During Week 2, much focus is placed on various strategic thinking models and the impact upon the overall organizational strategic process. Now that you have a broad knowledge of your chosen organization, it is time to dig a bit deeper into the structure and the process by which decisions are made within the company. Define the specific organizational design and the governance structure of the chosen company. Support your choices with specific examples and research.
During Week 1, you researched and identified a specific problem or challenge the organization is experiencing. Describe the challenge and explain why it is a problem for the organization. Include how the problem is or has the potential to affect the strategies of the company. Be specific and support your findings.
Section 2 of the paper must have at a minimum two full pages of content (excluding the cover and reference pages). You must include at a minimum two scholarly resources (in addition to the text) that support specific strategies used to prepare the paper. Wikipedia is not a qualified resource.
\
document for additional guidance. Include the text as a scholarly resource to support theory and concepts related to strategy. During the construction of Section 2, be specific and refrain from assumption.
.
During this time when the Internet provides essential communicat.docxkanepbyrne80830
During this time when the Internet provides essential communication between literally billions of people and is used as a tool for commerce, social interaction, and the exchange of an increasing amount of personal information, security has become a tremendously important issue for every user to deal with.
There are many aspects to security and many applications, ranging from secure commerce and payments to private communications and protecting health care information. One essential aspect for secure communications is that of cryptography. But it is important to note that while cryptography is necessary for secure communications, it is not by itself sufficient.
please
describe the hashing security mechanism
and its relationship to the encryption mechanism. Kindly write 350 words and add references at the end.
.
During this second week, you explored the knowledge base and his.docxkanepbyrne80830
During this second week, you explored the knowledge base and history of social work. We have examined specific social work professions as well as the great strides social workers have made in the U.S. with helping individuals, thus making a difference nationally.
For your assignment this week, identify three influential figures in social work – one person of color, one female, and one of your choice. Briefly, describe their accomplishments and their contributions to the social work knowledge base.
Next, select one of the three and discuss how this individual might approach the social issue/problem you identified in Week 1. If possible or appropriate, include an example that illustrates how this individual might address the problem.
Support your assignment with at least three scholarly resources. In addition to these specified resources, other appropriate scholarly resources, including seminal articles, may be included.
Length: 2-3 pages, not including title and reference pages
.
during the period from 1492 to 1700 french activity in the amer4ica.docxkanepbyrne80830
during the period from 1492 to 1700 french activity in the amer4ica was primarly directed toward a establishing trade with american indians b. using american indian settlmens for gold And silver c. conquering spanish and english colonies d encouraging the growth of permanent settlements e. discovering a new route to aasia
.
During the previous 30 years, the airline industry has experienced m.docxkanepbyrne80830
During the previous 30 years, the airline industry has experienced many mergers and bankruptcies.
For this discussion, provide at least one specific example of an operational change that occurred as the result on an airline merger or acquisition. Possible sources include
Securities and Exchange Commission (Links to an external site.)
filings, airline websites, biographies, NTSB reports, etc.
APA format applies to references and citations (Approximately 250 words)
.
During the semester you should record environmental events weather .docxkanepbyrne80830
During the semester you should record environmental events: weather events (heavy rain, drought, winds, freezes), earthquakes, volcanic eruptions, floods and coastal inundation, tsunami events (seismic waves), biodiversity issues and species extinctions, landslides, record icebergs, Antarctic ice-shelf disintegration, stratospheric ozone updates, air pollution occurrences, or other significant events related to the physical elements of the environment.
Your event log must include at least twelve events. Your log must include the date the event happened, the source from which you found the information, the type of event it is, and a brief paragraph about the event. Your list of events must be typed and put in chronological order.
You can use print media (newspapers, magazines, newsletters) or the internet as a source of information for learning about the latest occurrences. If you choose to use internet sources they
must
be legitimate news sources, not somebody’s blog.
The purpose of this exercise to show you how much of physical geography is actually occurring out there in the “real world”. Only record events that occurred this year – do not record events that happened in prior years.
Example
Date: September 24th
Source: Los Angeles Times
Event: Air Pollution
San Pedro is one of the busiest ports in the United States. Environmental justice activists are gaining influence, taking on the San Pedro Bay ports over contamination of the neighborhoods along transportation corridors. Soot and nitrogen oxides from ships, trains, and trucks are linked to asthma, cancer, and heart disease. Last year, 5,339 ships docked at the two ports. The new rules are forcing ships to switch to low-sulfur fuel within 24 miles of the coast and to plug into electrical outlets while they are docked. The ports pledge to cut pollution by 45% by 2012.
.
During the period 1350 to 1607, numerous changes in thought were occ.docxkanepbyrne80830
During the period 1350 to 1607, numerous changes in thought were occurring across Europe.
Your context should describe the philosophies that were most popular in Europe prior to 1350.
● Your thesis statement should provide a list of three new ways of thinking that developed between 1350
to 1607.
● The skill you are using is still causation , so you will be explaining how the new way of thinking caused a
change in Europe (or in places where Europeans were living and interacting).
● The end result of your essay will still be a five-paragraph essay.
● The final paragraph will still describe the effect that these new ways of thinking had on Europe.
.
During the mid 18th Century, English colonists appealed to the met.docxkanepbyrne80830
During the mid 18th Century, English colonists appealed to the metropole for redress of various grievances. In this essay, I want you to consider the ethics and civics of those seeking change (later known to us as the Patriots). Who were these Patriots? What methods did they use to further their goals through civic engagement? What ethical considerations did they take into account in seeking redress of their grievances? Did the new United States (under either the Articles or Constitution) address their grievances?
.
During the 1930s, much of the world seemed to give up on their h.docxkanepbyrne80830
During the 1930s, much of the world seemed to give up on their hope for a democratic solution to their problems and instead turned to totalitarianism, both in Europe and in select and address
one
of the following:
Address one of the following
USSR/Stalin
Japan/Tojo
Address the following questions for your selection:
What effects did the history, politics, and economies of those areas play in their decisions to turn to totalitarianism?
What role did the Great Depression in the United States play in their plight?
include in-text citation and apa format
.
Due Monday Feb 15, 2021InstructionsResearch a court case.docxkanepbyrne80830
Due Monday Feb 15, 2021
Instructions
Research a court case that involves the Fourth Amendment and the police authority to perform searches. Provide an overview of the case, discuss the purpose of the Fourth Amendment, and discuss the outcome of the incident.
Your case study must be at least two pages in length, not counting the title page and references page. A minimum of two references must be used,. Adhere to 7th edition APA Style when constructing this assignment, and make certain to include in-text citations and references for all sources that are used. Please note that no abstract is needed.
Safeassign will be used to check for plagiarism
.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
e-mail [email protected]Effect of Heat Treatment on Some M.docx
1. *e-mail: [email protected]
Effect of Heat Treatment on Some Mechanical Properties of
7075 Aluminium Alloy
Adeyemi Dayo Isadarea, Bolaji Aremob, Mosobalaje Oyebamiji
Adeoyec,
Oluyemi John Olawalec*, Moshood Dehinde Shittuc
aPrototype Engineering Development Institute Ilesa, Nigeria
bCentre for Energy Research and Development, Obafemi
Awolowo University, Ile-Ife, Nigeria
cDepartment of Materials Science and Engineering, Obafemi
Awolowo University, Ile-Ife, Nigeria
Received: April 14, 2012; Revised: September 3, 2012
This paper reports the effects of annealing and age hardening
heat treatments on the microstructural
morphology and mechanical properties of 7075 Al alloy. The
material was cast in the form of round
cylindrical rods inside green sand mould from where some
samples were rapidly cooled by early
knockout and others gradually cooled to room temperature.
From the samples that were gradually
cooled some were annealed while others were age hardened.
Both the as-cast in each category and
heat treated samples were subjected to some mechanical tests
and the morphology of the resulting
microstructures were characterised by optical microscopy. From
the results obtained there is formation
2. of microsegregations of MgZn
2
during gradual solidification which was not present during
rapid
cooling. It was also found out that age hardening and annealing
heat treatment operation eliminated
these microsegregations and improve mechanical properties of
7075 Al alloy. It is concluded that
microsegregation can be eliminated by rapid solidification and
appropriate heat treatment process.
Keywords: 7075 aluminium, microsegregation, precipitation
hardening, annealing, magnesium alloy,
strength
1. Introduction
Aluminium and its alloys are used in a variety of cast and
wrought forms and conditions of heat treatment. For over
70 years, it ranks next to iron and steel in the metal market.
The demand for aluminium grows rapidly because of its
unique combination of properties which makes it becomes
one of the most versatile of engineering and construction
material1-3.
The optimum properties of aluminium are achieved by
alloying additions and heat treatments. This promotes the
formation of small hard precipitates which interfere with
the motion of dislocations and improve its mechanical
properties4-7. One of the most commonly used aluminium
alloy for structural applications is 7075 Al alloy due to its
attractive comprehensive properties such as low density, high
strength, ductility, toughness and resistance to fatigue8-11. It
has been extensively utilized in aircraft structural parts and
3. other highly stressed structural applications12-16.
But aluminium-zinc alloy as it is in 7075 Al alloy is
susceptible to embrittlement because of microsegregation
of MgZn
2
precipitates which may lead to catastrophic
failure of components produced from it17,18. The alloy is also
susceptibility to stress corrosion cracking19,20. This is due to
inhomogeneity of the alloy and inherent residual stresses
associated with its fabrication methods.
The formation of these microsegregations (hard
precipitates) and inherent residual stresses that are associated
with their fabrication methods have serious negative effect
on their mechanical properties18. Hence, this study is aimed
at resolving the problems of microsegregations and inherent
residual stresses that are associated with aluminium-zinc
for improved service performance. The objectives of
the work are to investigate the effects of annealing and
precipitation hardening (age hardening) heat treatment on
the microstructure, hardness, tensile strength, and impact
strength of aluminium-zinc alloy.
2. Experimental Procedure
2.1. Material preparation
The present investigation was carried out on 7075 Al
alloy composition shown in Table 1. The material was cast
in the form of round cylindrical rods of 20 mm diameter and
500 mm long. Some of the cast rods were rapidly cooled
to room temperature by knocking them out 5 minutes after
5. 2.3. Tensile testing
Tensile testing of all these specimens was conducted
per British Standard BSEN 10002-1:1990. Three samples
were tested from each heat-treated condition and as cast
samples. The tests were carried out at room temperature
with a crosshead speed of 1 mm/min using a computerised
Instron 3369 electromechanical testing machine.
Load – displacement plots were obtained on an X-Y recorder
and ultimate tensile strength and percentage elongation
values were calculated from this load – displacement
diagrams. The average values from three test samples are
reported here.
2.4. Impact testing
Impact testing of all these specimens was conducted
per ASTM Standard E 602-91. Three samples were tested
from each heat-treated condition and as cast samples. The
tests were carried out using Izod impact test method on
Houndsfield balance impact-testing machine. The amount
of impact energy absorbed by the specimen before yielding
was read off on the calibrated scale attached to the machine
as a measure of impact strength in Joules. The average values
from three test samples are reported here.
2.5. Hardness test
The control and the heat treated samples were
subjected to the Brinell hardness test using the Houndsfield
extensometer in compression mode. The specimens were
polished to 600 microns and mounted on the machine using a
dwell time of 15 seconds. The diameter of the impression left
by the ball was then measured using the Brinell calibrated
hand lens and the corresponding Brinell hardness number
was determined.
6. 2.6. Optical metallography
The heat treated and as cast samples were taken
through the process of metallography: sample selection,
mounting, grinding, polishing and etching. The morphology
of the microstructures were then characterised by optical
microscopy after etching with sodium hydroxide.
3. Results and Discussions
Figures 1 to 4 show the microstructures of the specimen
in as-cast (gradually cooled), as-cast (rapidly cooled),
annealed and aged hardening condition respectively.
The microstructure of as-cast (gradually cooled) sample
(Figure 1) shows microsegeregation of MgZn
2
in aluminium
matrix while as-cast (rapidly cooled) sample (Figure 2)
shows fine grains of MgZn
2
phase which is uniformly
distributed in the aluminium matrix. The microstructure of
annealed sample (Figure 3) shows coarse grains of MgZn
2
phase which is non-uniformly distributed in the aluminium
matrix while the microstructure of age hardening sample
(Figure 4) shows the finely dispersed precipitate of MgZn
7. 2
in
aluminium matrix. The presence of dispersed precipitate of
MgZn
2
correspond with the result of Salamci23 and Du et al.24
who discovered that aging heat treatment of Al-Zn-Mg-Cu
alloys lead to the formation of MgZn
2
intermetallic phase
in the structure.
Table 1. Chemical composition of 7075 aluminium alloy.
Element %wt.
Zn 5.6
Mg 2.5
Cu 1.6
Al Balance
Figure 1. Microstructure of gradually cooled as-cast 7075 Al
alloy
showing microsegregation of MgZn2 in Al matrix.
Figure 2. Microstructure of rapidly cooled as-cast 7075 Al alloy
showing MgZn2 Phase in Al matrix.
8. 2013; 16(1) 191
Isadare et al.
In their study on evolution of eutectic structures in
Al-Zn-Mg-Cu alloys Fan et al.25, reported that several coarse
intermetallic phases such as MgZn
2
, Al
2
Mg
3
Zn
3
, Al
2
CuMg,
Al
2
Cu, A
l7
Cu
2
Fe, Al
13
9. Fe
4
and Mg
2
Si can be formed below
the solidus line during solidification of as-cast 7000 series
of aluminium alloys as a result of solute redistribution of
metals. This report supports our finding of microsegeregation
of MgZn
2
in 7075 Al alloy in gradually cooled sample. In
a rapidly cooled sample there was no room for solute
redistribution of Mg and Zn and hence microsegregation of
MgZn
2
is not formed. However, during the soaking period
of heat treatment operations the microsegregations formed
after gradual cooling are dissolved to form a homogeneous
phase and they disappeared after subsequent cooling. The
elimination of microsegregations after annealing and aging
heat treatment operations in the present investigation is
in agreement with the findings of Guo et al.26 who finds
out that solution treatment markedly reduce the degree of
microseregation in 2024 wrought aluminium alloy.
From the results of mechanical test as presented in
Table 2; the as-cast (gradually cooled) samples has the
highest ultimate tensile and yield strengths followed by age
hardened samples, as-cast (rapidly cooled) and annealed
10. samples. The as-cast (gradually cooled) sample has the
highest hardness and strength because of the presence of
miccrosegregations in its structure which embrittles 7075 Al
alloy. The reason for the observed trend in hardness and
strength in the remaining samples is due to the variations
in their grain size. This is in agreement with the findings of
Kenji et al.27 which indicated that solid-solution and grain
refinement contribute to the hardening of Al-Mg alloys.
Also, it is well reported in previous studies that fine-grained
materials has more grain boundaries; and are harder and
stronger than coarse grained materials that has less grain
boundaries28-30. Since age hardened sample has more grain
boundaries than as-cast (rapidly cooled) and annealed
samples there is more impediment to dislocation motion
during deformation and hence it is harder and stronger31.
For most materials the yield strength σ
y
varies with grain
size according to Hall-Petch relation:
σ
y
=
σ
o
+
k
y
11. d–1/2
In this expression d is the average grain diameter, σ
y
and
k
y
and are constants for a particular material.
The improvement in yield strength and ultimate tensile
strength as a result of grain size can also be explained from
the microstructures perspectives. The finer these grains are
the more the boundaries. During plastic deformation, slip
or dislocation movement must take place across these grain
boundaries. Since polycrystalline grains are of different
crystallographic orientations at the grain boundaries, a
dislocation passing from one grain to another will have to
change its direction of motion. Such changes of direction
causes impediment to dislocation movement, and increases
both the yield strength and ultimate tensile strength. Because
age hardening samples have the highest number of grain
boundaries, dislocation movement becomes more and more
difficult during plastic deformation. This is responsible for
highest yield strength and ultimate tensile strength observed
in age hardening samples. Also, 7075 Al alloy used for this
study contains about 5.6% zinc (Zn) and 2.5% magnesium
(Mg). These two alloying elements lead to increase in the
strength of this alloy through formation of MgZn
2
precipitate
within the structure as the result of aging heat treatment.
This result corresponds with Du et al.24, Li and Peng11,
12. Demir and Gündüz32 and Kaya et al.33 who concluded that
Al-Zn-Mg alloy can get the highest strength level in natural
and artificial ageing.Figure 4. Microstructure of aged hardening
7075 Al alloy showing
precipitate of MgZn2 in Al matrix.
Table 2. Results of mechanical testing for as-cast and heat
treated Al-Zn-Mg samples.
Samples
Yield strength
(MPa)
Ultimate tensile
strength (MPa)
Percentage
elongation
Hardness number
(HB)
Impact strength
(J)
As-cast (gradually cooled) 526 603 10 201 9.2
As-cast (rapidly cooled) 467 529 17 157 17.7
Annealing 297 414 21 124 22.4
Age hardening 501 575 15 171 14.7
Figure 3. Microstructure of annealed 7075 Al alloy showing
MgZn2
13. phase in Al matrix.
250 µm
192 Materials Research
Effect of Heat Treatment on Some Mechanical Properties of
7075 Aluminium Alloy
Annealing sample has the highest percentage elongation
followed by as-cast (rapidly cooled), age hardening
samples, and as-cast (gradually cooled). This is partly due
to increase in grain coarsening which leads to an increase
in the grain boundary area which increases the amount of
energy required for the movement of dislocations required to
cause fracture34-36. Thus, the material can withstand a higher
plastic deformation before the final fracture. However, the
percentage elongation of as-cast (gradually cooled) is very
small because of embrittlement of 7075 Al alloy as a result
of microsegregation of MgZn
2
.
As-cast (gradually cooled) sample has extremely high
hardness as a result of its brittle structure. From the remaining
three samples age hardening heat treatment samples has the
highest hardness followed by as-cast (rapidly cooled) and
annealed samples. The highest hardness values developed
by age hardening samples can be attributed to precipitation
of coherent and finely dispersed MgZn
2
phases which serves
14. as foreign atom or inclusion in the lattice of the host crystal
in the solid solution; this causes more lattice distortions
which makes the alloy harder. In the previous study solid
solution strengthening from elastic distortions is produced
by substitutional atoms of Mg and Zn in aluminium matrix37.
Hence, the main strengthening mechanism in these alloys is
precipitation hardening by structural precipitates of MgZn
2
formed during artificial ageing. The precipitate particles act
as obstacles to dislocation movement and thereby strengthen
the heat-treated alloys.
The impact strength followed the same trends as
percentage elongation with annealing sample been the
highest and as-cast (gradually cooled) sample been the least.
This is because impact strength is also a measure of material’s
ductility, and ductility is inversely related to strength38.
4. Conclusions
From the outcome of this study, there is formation of
microsegregations of MgZn
2
during the gradual solidification
of 7075 aluminium alloy due to solute redistribution of Mg
and Zn but this was suppressed during rapid solidification.
However, the microsegregations that were formed when it
was gradually cooled are dissolved to form a homogeneous
phase during the soaking period of heat treatment operations.
As a result of age hardening heat treatment operation there is
formation of small and finely uniform dispersed precipitate
15. of MgZn
2
in the aluminium matrix while coarse grains of
MgZn
2
phase was formed in aluminium matrix as a result
of annealing heat treatment operation.
It has been found that rapid solidification process and
heat treatment eliminate the formation of microsegregation,
and significantly improved some mechanical properties. Age
hardening heat treatment operation was found to improve
yield strength, ultimate tensile strength and hardness values
but lower ductility and impact strength. On the other hand
annealing heat treatment operation improves impact strength
and ductility but lower yield strength, ultimate tensile
strength and hardness values. Therefore, annealing treatment
of the alloy will be suitable for applications involving high
toughness and ductility while age hardening treatment will
be suitable for applications that require high ultimate tensile
strength, yield strength and hardness values.
Finally, it is concluded that the formation of
microsegregation embrittle 7075 aluminium alloy, and
subsequently have negative effects on its mechanical
properties and its application. This can be addressed by
rapid solidification and appropriate heat treatment process.
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23. COLLEGE OF ENGINEERING
DEPARTMENT OF MECHANICAL & INDUSTRIAL
ENGINEERING
BEng (Honours) in Computer Aided Mechanical Engineering
Academic Year: 2018-19 Semester: B
MHH124725: Technical Project
Final Report
Project Title: Corrosion Analysis of Aluminum Alloy 7075.
Student Name: Amani Al Ajmi
Student Number: 140150
Supervisor(s): Mr. Said Al Oraimi
24. Declaration by the Student
I declare that this project report / dissertation titled
_____________________________
_____________________________________________________
___________________
is my own work and has not been submitted in any form for
another degree or diploma at any university or other institutions
of tertiary education. Information derived from the published
work of others has been acknowledged in the text and a list of
references is given. I am fully aware of the College’s policy on
plagiarism and cheating, and that the penalty for submission of
plagiarized report could result in a ‘fail’ in Technical Project /
Dissertation. I have submitted a copy of this full report in
electronic form to my supervisor.
Signature of the Student: Date:
Name of the Student:
Student Number:
25. Certificate by the Supervisor
The project report / dissertation titled
_________________________________________
_____________________________________________________
__________________
is the bonafide work of Mr./ Ms.
______________________________________________, and
bearing student number ______________ is carried out under
my supervision. I certify that the work presented in the project
report / dissertation is carried out by him / her, and that he / she
has achieved the set objectives of the project / dissertation.
Information derived from the published work of others has been
acknowledged in the text and a list of references is given at the
end of the report. I have personally checked this final report for
originality / plagiarism through the Turnitin website and, to the
best of my knowledge and belief, satisfied that the report is free
from plagiarism.
Signature of the Supervisor:
Date:
Name of the Supervisor:
Countersigned by HoD:
ACKNOWLEDGEMENT
26. The acknowledgement by the candidate for successfully
carrying out the project work
ABSTRACT
Aluminum plays an important role in a number of industrial
applications such as construction and electrical engineering. It
is also quite applicable in the transport industry where it is used
in the manufacturing and production of machinery used in the
aircraft building. Although aluminum and its alloys are quite
useful, they are subject to corrosion as a result of chemical
interaction with the surroundings and hence do not the best
materials for engineering applications. One of the main
significant problems faced by aluminum components used in the
aircraft is pitting corrosion. An experimental analysis of
components of aluminum in aircraft to identify corrosion will be
carried out in this project. Findings indicate severe corrosion of
nose landing component leading to its failure. Pitting corrosion
refers to the restricted high metal dissolution as a result of
depletion of the passive film on the metal surface that acts as a
protective cover. This study aims at bringing into discussion an
analysis of corrosion in the aluminum alloy (7076) mainly used
in aircraft components. Therefore, this project identifies the
details on materials, undertaking taste samples on the identified
materials, and measures are undertaken to improve corrosion
resistance. Hence, development of the two types of coating, and
testing their levels of resistance to corrosion.
This experiment identifies two types of heat treatment
experiments useful in testing samples with and without coating
condition. An examination will be carried out on the behavior of
the metal using hardness testing before and after heat treatment,
measurement of the surface roughness, corrosion test in sea
water followed with an acid test. Analysis of these results
finally will be carried out to achieve the objectives
successfully.
27. Keywords: Aluminum alloy (7076)، Pitting corrosion, Hardness
testing, Heat treatment.
TABLE OF CONTENTS
The content shall follow the abstract and indicate the page
numbers of the chapters, sections, sub-sections, appendices and
references. The number and titles of all the items must be
clearly entered with page numbers against them.
LIST OF TABLES
Table Number
Description
Page No.
Table 4.1
Hardness readings before heat treatment.
Table 4.2
Hardness readings after heat treatment.
Table 4.3
Roughness measurements.
Table 4.4
Weight loss.
28. LIST OF FIGURES
Figure Number
Description
Page No.
Figure 1.1
Pitting Corrosion.
Figure 1.2
Aircraft Material.
Figure 3.1
Morgen Rushworth RGMS.
Figure 3.2
Aluminum Alloy Sheet Before cutting.
Figure 3.3
Aluminum Alloy Sample After cutting.
Figure 3.4
Metallic Stamp.
Figure 3.5
Hammer.
Figure 3.6
Samples After Numbering.
Figure 3.7
Aluminum Oxide and Aluminum paint.
29. Figure 3.8
During the Painting Step.
Figure 3.9
Sample After Applying the First layer of Coating.
Figure 3.10
Zinc Spray and the Samples Before Coating.
Figure 3.11
The Samples After Zinc Coating.
Figure 3.12
Underbody Rubber Spray.
Figure 3.13
The Samples After Rubber Coating.
Figure 3.14
Furnace during
Figure 3.15
Quenching Samples in Water.
Figure 3.16
Rockwell Hardness.
Figure 3.17
Indenter Used for Testing.
30. Figure 3.18
Roughness Device (Mitutoyo) connected to Computer Software.
Figure 3.19
During Roughness Measurement for Zinc Sample.
Figure 3.20
Samples immersed in Seawater.
Figure 3.21
Apparatus used for HCL Test.
Figure 3.22
HCl
Solution
.
Figure 3.23
Sample Without Coating Initial Weight.
Figure 3.24
Sample Without Coating Weight After Seawater and HCL Tests.
32. Rz and Rq Values of the Samples.
Figure 4.8
Weight Loss (g) of the Samples.
LIST OF SYMBOLS AND ABBREVIATIONS
NaCl – Sodium Chloride.
HCL – Hydrochloric Acid.
H2O – Water.
Al – Aluminum.
% – Percentage.
Zn – Zinc.
Al2O3 – Aluminum Oxide.
PH – Potential Hydrogen.
Chapter name & title
1
16
33. CHAPTER 1INTRODUCTION
1. Introduction.
Corrosion is the deterioration of materials by chemical
interaction with the surrounding environment; it is a natural
phenomenon which can be controlled by correcting the
condition when an early warning signs occurs. Airframe issues
related to corrosion have plagued the aerospace industry for
decades. The metals of aircraft components are exposed to
different forms of corrosion; there are many agents which
accelerates the corrosion process such as prolonged exposure to
corrosive factors including moisture, salts and industrial fluids.
The main source of corrosion is water vapor containing salt that
combines with the oxygen in the air. The appearance of
corrosion differs depending on the type of the metal, on the
aluminum alloy surface it shows as pitting which is combined
with white or gray powdery deposit. This project will provide
an experimental study on the corrosion analysis of aluminum
alloy where 75% of aircraft structures are made of aluminum as
shown in Figure 2.
34. Figure 1.1 Pitting Corrosion
Figure 1.2 Aircraft material
1.1 Problem statement:
Pitting corrosion is one of the most common problems faced by
aluminum components used in aircraft, as the name implies this
type of corrosion means the formation of small holes in the
surface of the material. Due to the high-speed landing of
aircraft on the dusty runway, the protective coating is removed
which lead to the exposure of the metals surface to the corrosive
factors.
1.2 The aim of the project:
To perform an experimental study about corrosion analysis of
aluminum alloy material used in aircraft component. 1.3 The
main objectives:
· Identify the causes of corrosion.
· Carry out the corrosion resistance process experimentally.
· Analyze the obtained result.1.4 Scope of studies:
· Literature review about corrosion in aluminum alloy material.
· Investigate and understand the working principle of the metal
35. coating and heat treatment to reduce the corrosion in aluminum
alloy.
· Implement roughness measurement of the coated samples
followed by corrosion test with sea water and acid.1.5
Importance of the research:
Understanding and analyzing the corrosion behavior is
important, there are many factors regarding the significance of
corrosion study including economic, by implement corrosion
control process, the useful life of aircraft can be extended,
therefore the maintenance cost will be reduced. Also, the best
insurance against corrosion associated failures is studying and
testing the metals used in the design of the planes in order to
select the proper ways to control the problem to increase the
safety of public.
CHAPTER SUMMARY
Corrosion is considered to be a natural phenomenon which can
be controlled through changing or altering the conditions
immediately after early warning signs are detected. Corrosion
has been a major concern within the Aerospace industry where
it has been leading to issues related to Airframe. In Aerospace
industry, metals of aircraft are becoming exposed to corrosion
and this activity is accelerated by prolonged exposure to
corrosive agents like moisture, salts, and industrial fluids.
Water vapor is considered to be the primary source of corrosion
and it is composed of salts which combine with oxygen in air.
36. One of the metals affected as a result of pitting corrosion is
aluminum components used in aircraft leading to the formation
of small holes in the surface of the material. This study aims at
identifying the causes of corrosion; carrying out the corrosion
resistance process experimentally; and analyzing the obtained
result. The scope of this study is to investigate and understand
the working principle of the metal coating and heat treatment to
reduce the corrosion in aluminum alloy; and implement
roughness measurement of the coated samples followed by
corrosion test with sea water and acid. There are a number of
advantages associated with this study. Through implementation
of corrosion control process, it is possible to extend the life of
aircraft can be extended thus helping in reducing the
maintenance cost.
CHAPTER 2:LITERATURE REVIEW
2. Introduction.
Corrosion refers to the process of material degradation as a
result of interaction with the environment. Corrosion occurs in
metals, polymers, and ceramics. The research on corrosion and
its alloys is an enormous area of research since it involves a
37. broad range of applications in areas such as marine, aerospace,
industrial and family environments. The main reason for its
usage is due to the good machinability, weldability, and good
corrosion resistance. Corrosion resistance of alloys is attributed
to the fact that they are naturally developing to an oxide film on
their surface as a result of environmental condition. However,
pitting corrosion is the main corrosion phenomenon which is
common and occurring due to the breakage in the oxide film.
Resistance to pitting of the metals is influenced by the physical,
electrical, and mechanical features of the passive layer. As a
result of perfect passivity with greater uniform corrosion
resistance to seawater, pitting remains the primary concern for
Aluminium Alloys in the environment with seawater.
This chapter includes some literature reviews which have been
referred to regarding corrosion analysis of Aluminum alloy.
2.1 Effect of heat treatment on some mechanical properties of
7075 aluminium alloy.
Adeyemi Dayo Isadare, Bolaji Aremo, Mosobalaje Oyebamiji
Adeoye, Oluyemi John Olawale, Moshood Dehinde Shittu,
(2013) work entails a detailed explanation of their experiment
which involved an examination of annealing on micro-structural
morphology as well as mechanical properties of 7075 Al alloy.
Additionally, the experiment evaluated the relationship between
age hardening on microstructural characteristics of 7075 alloy.
38. The researchers concluded from the experiment results that
annealing heat treatment had the power to do away with micro-
segregation. Age hardening heat treatment was also observed to
bring an improvement on mechanical characteristics of the
Alloy (Isadare, Aremo, Adeoye, Olawale & Shittu, 2013). This
work perfectly fits the topic since it shed light on how the
project topic can be handled. This stem from the fact that the
work reveals that age hardening heat treatment can improve the
mechanical property of the aluminum alloy. One such
characteristic is resistance to corrosion. To make the allow
resistant to corrosion by other elements or acids using the
results from Adeyemi Dayo Isadare, Bolaji Aremo, Mosobalaje
Oyebamiji Adeoye, Oluyemi John Olawale, Moshood Dehinde
Shittu (2013) work it’s hence recommendable to do age
hardening heat treatment.
2.2 Quenching of aluminum alloys: cooling rate, strength, and
inter-granular corrosion‖.
Patricia Kavalco, Canale Lauralice and George Totten (2009)
research entails the study of intergranular corrosion. The
researchers investigated how intergranular corrosion could be
used to reduce corrosion. In the study, it was found out that the
cooling rate of any aluminum alloy determined the rate of
pitting corrosion. The slower the rate of cooling the fewer
39. chances an aluminum allow being affected by corrosion. On the
other hand, if an alloy was quickly cooled the impact would be
that the alloy would be easily corroded by corrosive reagents or
chemicals (Kavalco, Lauralice & Totten, 2009). On that note,
the authors recommend that while making any aluminum allow
it was crucial to give attention to the cooling rate. In the event
that the alloy will be exposed to highly corrosive agents, it is
advisable to have the cooling rate very slow and vice versa.
This work is useful in informing the topic that is corrosion in
Aluminum alloy. With the findings from the source, one can
state that corrosion in aluminum alloys is dependent on the rate
of cooling of the alloy during its making.
2.3 Improvement Properties of 7075-T6 Aluminum Alloy by
Quenching in 30% Polyethylene Glycol and Addition 0.1%B‖.
Jasim Salman, Shaymaa Alsada and Khadim Al-Sultani (2013)
work discusses the results of their experiment. The experiment
was set up to investigate the impact of sodium chloride,
polyethylene glycol and boron on aluminum alloy. The authors
wanted to know whether the combination of these solutions or
elements could improve the feature of the 7075-T6 alloy. The
target features were corrosion resistance, toughness as well as
thermal aging behavior. The researchers took 3.5% NaCl, 30%
polyethylene glycol and Boron solution and treated 7075- T6
40. alloy with. The results indicated that the solution improved the
toughness feature of the alloy by 50%. However, the corrosion
property was not significantly influenced by the solution. This
indicates that the solution cannot be used to improve the
corrosion resistance of the alloy (Salman, Alsada& Al-Sultani,
2013). Generalizing the case to other types of aluminum alloys
one can draw an insight that a mixture of boron, sodium
chloride and polyethylene glycol have no properties in
improving the corrosive resistance feature of an aluminum
alloy. On that note, the work is significant in this topic since it
gives direction on elements and solution which should not be
used while improving the resistance features of an aluminum
alloy.
2.4 Recent developments in advanced aircraft aluminum alloys.
Tolga Dursun and Costas Soutis (2014) work is about their
review on the recent aluminum technology employed in aircraft
industry which is one area aluminum alloys are industrially
41. exploited. The authors learned that the technology has led to
having damage tolerant, strong, tough and corrosion resistant
alloys. The review shows that a combination of Aluminum and
zinc leads to a very strong alloy. Mixing Aluminum and copper
results to a high damage resistant alloy. Of key importance in
this context is mixing aluminum and lithium that is AL-Li. The
outcome is an alloy with improved properties such that the alloy
is has higher fracture toughness and is corrosion resistant
(Dursun& Soutis, 2014). This work is essential in the study of
this topic from the angle that it shows the right chemical
composition that can be used to have a high corrosion resistant
alloy.
2.5 Aluminum Alloys for Aerospace Applications‖, Aerospace
Materials, and Material Technologies.
The work entails a history of aerospace technology with
aluminum alloys in focus. Also, entails classification of
aluminum alloys. The classification is based on temperatures
used to heat and cool the alloys. This is because the
temperatures are a significant determinant of the strength
property as well as other features (Rambabu, Prasad& Wanhill,
2017). Additionally, the work entails weaknesses or gaps in the
current aluminum technology used in aerospace. These gaps are
crucial in handling the topic given that they will show areas that
require more research in improving the corrosion resistance
42. feature of aluminum alloys.
2.6 Aluminium alloy corrosion of aircraft structures: modelling
and simulation.
To prevent corrosion occurrences, Aluminum and its alloys
were properly handled using various protection methods that
prevent corrosion of the aircraft. These methods include:
waxing, painting, zinc-chromate priming, coating using thin
layer of Alclad, anodizing and coating with a liquid protective
solution (DeRose, 2013 pg. 23-29).
Barrier coating using materials such as paint, plastic, wax or
powder was applied and left out for some time for later
observations. Aluminum was also coated using a thin layer of
pure aluminum. Pure aluminum was successfully sprayed on the
aluminum flat and round coupons at low temperatures. Hardness
test was then carried out before and after the heat treatment
Demo, (Steiner, Friedersdorf, and Putic, 2010 pg. 1-9).
Aluminum specimen was heated at 500 Celsius and then
quenched in cold oil. Hardness of the heat-treated specimen and
those without heat treated specimen was measured in and
recorded. Resistance to corrosion of the samples was evaluated
in 3.5 % sodium chloride solution by weight loss method.
Corrosion test was also conducted in wet conditions which
included seawater and hydrochloric water conditions.
Roughness measurements were also conducted on the final
43. product.
2.7 Milestone case histories in aircraft structural integrity.
We found out that epoxy, nylon and urethane which are types of
powders, which were heated and placed on the aluminum
surface to form a thin film layer offered protection from
corrosion. Plastic and waxes which were sprayed onto the
aluminum surfaces acted as a coating to offer protection to
aluminum surface from mixing with other corrosive elements
that lead to corrosion (Wanhill, Molent, Barter and Amsterdam,
2015 pg. 346) People have come up with current painting
systems in the aircraft components that combine different
painting layers which have been designed to serve different
functions. They are usually applied in three layers. The first
spray paint acts as the inhibitor which decreases the activity of
the aluminum and its alloys or blocks it from combining or
reacting with other corrosive elements. The second and
intermediate layers of paint coats are applied to add to the
overall thickness of the paint and to make sure that no
aluminum surface is left exposed (Kiyak, 2012 pg. 9-16) The
last and finish coat is primarily designed to offer resistance to
the environmental factors such as humidity, pH concentration
and alkaline concentration of the surrounding.We also found out
that pure aluminum coating component insulates and protects
aluminum from corroding. This helped in reducing the extent of
44. corrosion.
2.8 Can pitting corrosion change the location of fatigue failures
in aircraft?
Regarding hardness test, it was found out that after heat
treatment at 500 °C and subsequent quenching in oil of
aluminum component the hardness and corrosion resistance of
pure aluminum improved whereas before heat treatment, the
hardness and corrosion resistance of the material was low.
Concerning corrosion in wet areas, we found out that aluminum
corrodes faster or quicker when placed in wet areas. This is
because the water component acts as a catalyst in the process of
corrosion (Crawford, Loader, Liu, Harrison, and Sharp, 2014
pg. 304-314). When Aluminum, which is the material used to
make aircrafts, is left unprotected in certain areas such as salty
areas near the ocean or sea waters, it will form an oxide layer
and corrodes almost immediately. Because of the corrosive
action of this strongest of acids like hydrochloric acid on metals
like aluminum, normally, non-metal materials are preferred,
when possible (Jaya, Tiong, and Clark, 2012 pg. 64-73).
Aluminum have useful corrosion resistance in low
concentrations of HCl. The corrosivity increases dramatically as
the concentration of HCl and temperature increase. This led to
an increased rate and extent of corrosion. Therefore, the extent
of destruction was higher in wet areas as compared to that one
in dry areas.
45. 2.9 Recent developments in advanced aircraft aluminium
alloys. Materials & Design.
The main disadvantage of using coating as a method of
preventing corrosion is that the coating components need to be
reapplied over and over again which is tiring and expensive.
Poorly applied coatings always fail and can lead to increased
rate and increased extent of corrosion (Dursun and Soutis, 2014
pg. 862-871). Sometimes, there might exist some volatile
organic components in certain coatings which make them
vulnerable to corrosion.
2.10 Role of chemical composition in corrosion of Aluminum
Alloy.
The current political environment in industrial application
demands the use of light structural materials for several reasons
including lower gas emissions, better fuel economy and reduced
energy consumption. Furthermore, taking into consideration
several proprieties, Aluminum alloy is the favourable material
for crafting many components for aerospace and automotive
applications due to its strong corrosion resistance, low density,
excellent formability and high weight to stiffness ratio.
46. The study was to establish the mechanical, physical and
chemical properties of alloys of Aluminum. This would be used
to identify the best alloy for the aerospace and automobile
industries. The literature review was done sufficiently and
highlighted that Aluminum alloys have become the most used
metals in the automobile and aerospace manufacturing
industries in the world.The alloys are used in aerospace and
automobile industries because of its physical properties and
durability. From the literature, it was established that important
properties that make Aluminum metal useful in various
manufacturing plants include its low density, excellent
formability property, high strength stiffness in relation to
weight and good corrosion resistance.
I will attach two more literature, analyze them same way as
seen in literatures above.
47. Chapter Summary.
This section provides some past researches and works related to
corrosion; each author studied the topic from different areas
including the relationship between age hardening on
microstructural characteristics of Al 7075 alloy which
concluded from the experiment results that annealing heat
treatment had the power to do away with micro-segregation.
Also, investigation on how intergranular corrosion could be
used to reduce corrosion where the authors recommend that
while making any aluminum allows it was crucial to give
attention to the cooling rate. Moreover, another author
discussed the impact of sodium chloride, polyethylene glycol
and boron on aluminum allow. In addition, another review
shows that a combination of Aluminum and zinc leads to a very
strong alloy. As well as the classification of aluminum alloy
were studied, and the author concluded that the classification is
based on temperatures used to heat and cool the alloys. This is
because the temperatures are a significant determinant of the
strength property as well as other features. Also, barrier coating
is one of the easiest and cheapest methods in preventing
corrosion in aircraft components made of aluminum. It was very
effective in preventing corrosion but only if proper procedures
were carried out carefully. Coating, therefore, insulates,
48. beautifies and increases the aircraft’s life expectancy. It is also
easy to apply and reflects 80% of ultraviolet rays. Though it
faces certain challenges, it is very effective in preventing
corrosion in aluminum, an aircraft component.
CHAPTER 3EXPERIMENTAL SETUP
3. Introduction.
This chapter includes the steps followed in order to achieve the
project objectives. First, samples preparation step which
involves two parts, cutting the Aluminum alloy sheet and
Numbering the samples. Then, the main step which is coating
the sample using three types of coating:
· Aluminum Oxide.
· Zinc.
· Underbody Rubber coating.
After the coating step, some investigations and tests were
carried out such as: Hardness test using Rockwell hardness test
before and after heat treatment. Also, Roughness measurements
using Mitutoyo device connected to computer software. In
addition to corrosion test in sea water for 192 hours followed
with a Hydrochloric test for 10 minutes in order to monitor the
weight loss of the samples.
49. 3.1 Samples Preparation.
For an accurate and fast cutting of the Aluminum alloy sheet, a
mechanical guillotine called Morgan Rushworth RGMS is used.
Figure 3.1 Morgen Rushworth RGMS
Figure 3.2 Aluminum alloy sheet before cutting
The following is the procedure of cutting the Aluminum Alloy
sheet using Morgen Rushworth RGMS.
1. Place the Aluminum sheet on the support table as shown in
Figure 3.2.
2. Switch on machine.
50. 3. Press SET write the desired position to the display.
4. Press START, machinery moves to the desired position.
5. Cutting operation will carried out.
6. Switch off machine.
Figure 3.3 Aluminum Alloy Sample After cutting.
Then, using metal stamps and hammer the numbering step is
done by applying the following procedure:
1. Place the desired number stamp on the sample.
2. Strike twice on the stamp using the hammer.
3. The number will appear on the sample.
4. Repeat the steps using different numbers for different
samples.
52. 3.2 Coating Step.
In this step I used three types of coating: Al2O3 (Aluminum
Oxide), Zinc and Underbody Rubber coating.
3.2.1 Aluminum Oxide Coating:
To achieve this type of coating an Aluminum Oxide powder,
Aluminum paint and a brush are required. The procedure is:
1. Prepare a mixture of 25 ml of Aluminum paint with 250 g of
Al2O3.
2. Place the mixture in the rotary shaker for one hour in order to
mix properly.
3. Apply the Aluminum oxide mixture on the sample using a
brush.
4. Put the coated sample in a place to be exposed to air for three
hours in order to dry then apply an extra layer if needed.
53. Figure 3.7 Aluminum Oxide and Aluminum paint.
Figure 3.8 During the Painting Step.
Figure 3.9 Sample After Applying the First layer of Coating.
3.2.2 Zinc Coating:
Zinc spray provides along-lasting cathodic corrosion protection
to all metal surfaces. Zinc spray is forming a fast-drying,
adherent protective layer of microfine zinc flakes. Zinc flakes
are forming a resistant protective layer even under extreme
54. weather and environmental conditions.
The following is the procedure for Zinc coating:
1. Shake the can well before using.
2. Spray evenly on the samples about 20 cm distance from the
surface.
3. Put the coated sample in a place to be exposed to air for three
hours in order to dry.
4. Repeat the second step until the desired thickness is obtained.
Figure 3.10 Zinc Spray and the samples Before Coating.
Figure 3.11 The Samples After Zinc Coating.
55. 3.2.3 Underbody Rubber Coating:
This type of coating is mostly used on cars to protect them from
damage, rusts, and decay. It is used in rust prevention and are
applied when the car is brand and new. The manufactures are
using thick paints as well as sealants for the Underbody and this
is made better by the addition of the Underbody coats.
Underbody coating is providing a long-lasting protection from
corrosion to the car’s Underbody. It also protects parts such as
the internal body panels, the frame rails, and other inner
cavities which are physically accessible but are more exposed to
corrosion.
The following is the procedure for underbody rubber coating:
1. Shake the can well before using.
2. Spray evenly on the samples about 20 cm distance from the
surface.
3. Put the coated sample in a place to be exposed to air for three
hours in order to dry.
4. Repeat the second step until the desired thickness is obtained.
56. Figure 3.13 The Samples After Rubber Coating.
Figure 3.12 Underbody Rubber Spray.
3.3 Heat Treatment.
Heat treatment is a group of industrial as well as metalworking
processes that are utilized in altering the physical, chemical,
and properties of a material. Heat treatment is also used in
manufacturing of many other materials.
3.3.1 Annealing.
Annealing process is carried out through heating of a sample
which has been machined, undertaken through hardness testing,
and metallographic to a temperature of 4700C. Soaking such
samples at a temperature of 4700C for about 2 hours is then
57. followed by cooling process using furnace.
3.3.2 Precipitation Hardening.
This procedure is performed by using a solution to treat another
set of test piece of sample which has been machined, undertaken
through metallographic and hardness test at 465 °C for 2 hours.
This process is then followed by quenching the samples rapidly
in cold water. The quenched samples then undergo precipitation
hardening, a process which is also referred to as age hardening
through a heating process of the samples to 120 °C for 3 hours.
The final step is the cooling process using the air within the
room.
58. 3.4 Hardness Test.
Using Rockwell hardness test which is a hardness scale based
on the indentation hardness of material. Rockwell test is
determining the hardness through measurement of the
penetration depth of an indenter under a huger load in
comparison to the penetration which has been made by the
minor load.
The working principle of this device as following:
1. Select the proper indenter depending on the type of the alloy
to be measured, for Aluminum Alloy 1/8 ball is used.
2. Turn the device on.
3. Place the sample to be measured on top of the anvil.
4. Rotate the anvil adjustment clock wise in order to rise the
anvil till it touch the surface of the sample.
5. The reading will appear on the screen, write it down and
repeat the steps using different coating samples.
59. Figure 3.16 Rockwell Hardness.
Figure 3.17 Indenter Used for Testing.
3.5 Roughness Measurements.
Roughness is the component of the surface texture. Its
quantification is based on the deviations towards the direction
of the normal vector of a real surface from the one which is
considered to be ideal form. In case the deviation is large, then
the surface is considered to be rough whereas if the deviations
are smaller, then the surface is smooth.
The following are the steps to measure the roughness of the
samples:
1. This device is connected to the computer software, first turn
on the computer and the device.
2. Place the sample to be measured as shown on Figure 3.17,
notice the movement of the tip on the surface of the sample for
60. about 5 seconds.
3. The surface roughness measurements will show on the
computer screen.
4. Repeat the steps using different coating samples.
Figure 3.18 Roughness device (Mitutoyo) connected to
computer software.
61. Figure 3.19 During Roughness Measurement for Zinc sample.
3.6 Corrosion Test in Seawater.
Sea water is also known as salt water and is water from the sea
or ocean. Sea water is considered to be playing a key role
towards increasing the rate of corrosion. Corrosion by sea water
is an electrochemical process and when it comes into contact
with all metals and alloys, it makes them have specific
electrical potential or corrosion potential at specific pH.
The corrosion test was carried out in Seawater In this test the
samples with and without coating were immersed in sea water
for 192 hours and the weight was measured before and after the
test.
3.7 Corrosion Test in Hydrochloric Acid (HCl).
In this test, a solution of 100ml of HCl and 900ml of H2O was
62. prepared and the samples with and without coating were treated
with the solution for 10 minutes and the weight of the sample
before and after the test were measured in order to monitor the
weight loss.
Figure 3.21 Apparatus used for HCL Test.
Figure 3.22 HCl