The document provides information on welding of non-ferrous alloys including aluminum alloys, titanium alloys, copper alloys, and nickel alloys. Specifically for aluminum alloys, it discusses alloy designations, temper designations, filler metals, factors to consider for welding such as cleaning, backing, preheating, and tack welding. It also covers welding processes for aluminum alloys including gas tungsten arc welding and gas metal arc welding, and issues that can occur such as porosity and cracking.
PPT Includes physical Metallurgy for Titanium and its alloys, Weld ability of them and two welding processes : GTAW and EBW. PPT also describes the Problems with the Welding of Titanium and alloys.
PPT Includes physical Metallurgy for Titanium and its alloys, Weld ability of them and two welding processes : GTAW and EBW. PPT also describes the Problems with the Welding of Titanium and alloys.
Welding Defects
Eurotech Now inteducing Welding Defects. Welding Defect is any type of flaw in the object which requires welding. Seven type of Welding Defect
Seven type of Common weld defects include:
1. Lack of fusion
2. Lack of penetration or excess penetration
3. Porosity
4. Inclusions
5. Cracking
6. Undercut
7. Lamellar tearing
Any of these defects are potentially disastrous as they can all give rise to high stress intensities which may result in sudden unexpected failure below the design load or in the case of cyclic loading, failure after fewer load cycles than predicted.
Welding process
Arc Welding
Resistance Welding
Oxy fuel Gas Welding
Other Fusion Welding Processes
Solid State Welding
Weld Quality
Weld ability
Design Considerations in Welding
Electron Beam Welding is a fusion welding process in which a beam of high-velocity electrons is applied to the material to be joined. The work-piece melt as the kinetic energy of the electrons is transformed into heat upon impact. The EBW process is well-positioned to provide industries with highest quality welds and machine designs that have proven to be adaptable to specific welding tasks and production environments.
This Presentation covers the basic concepts of Hot cracks and cold cracks in welding. For more information, please refer the books mentioned in the references slide.... Thank you
What is laser beam hardening (LBH)? Advantages, Disadvantages
Applications, What is laser peening? Difference between laser beam hardening (LBH) and electron beam hardening (EBH)
The Certified Welding Inspector (CWI) plays an important role during any welded construction activities ensuring the required specifications and standards are followed. Due to the numerous materials and processes associated with metal joining (welding) THIS PRESENTATION SHALL SHOW ONLY THE BASIC WELDING PROCESSES AND EXAMINATION METHODS (NDE). National and International Codes and Specifications along with measuring devices are the Inspector’s tools. Hopefully the following presentation shall give an insight into basic welding inspection.
Welding Defects
Eurotech Now inteducing Welding Defects. Welding Defect is any type of flaw in the object which requires welding. Seven type of Welding Defect
Seven type of Common weld defects include:
1. Lack of fusion
2. Lack of penetration or excess penetration
3. Porosity
4. Inclusions
5. Cracking
6. Undercut
7. Lamellar tearing
Any of these defects are potentially disastrous as they can all give rise to high stress intensities which may result in sudden unexpected failure below the design load or in the case of cyclic loading, failure after fewer load cycles than predicted.
Welding process
Arc Welding
Resistance Welding
Oxy fuel Gas Welding
Other Fusion Welding Processes
Solid State Welding
Weld Quality
Weld ability
Design Considerations in Welding
Electron Beam Welding is a fusion welding process in which a beam of high-velocity electrons is applied to the material to be joined. The work-piece melt as the kinetic energy of the electrons is transformed into heat upon impact. The EBW process is well-positioned to provide industries with highest quality welds and machine designs that have proven to be adaptable to specific welding tasks and production environments.
This Presentation covers the basic concepts of Hot cracks and cold cracks in welding. For more information, please refer the books mentioned in the references slide.... Thank you
What is laser beam hardening (LBH)? Advantages, Disadvantages
Applications, What is laser peening? Difference between laser beam hardening (LBH) and electron beam hardening (EBH)
The Certified Welding Inspector (CWI) plays an important role during any welded construction activities ensuring the required specifications and standards are followed. Due to the numerous materials and processes associated with metal joining (welding) THIS PRESENTATION SHALL SHOW ONLY THE BASIC WELDING PROCESSES AND EXAMINATION METHODS (NDE). National and International Codes and Specifications along with measuring devices are the Inspector’s tools. Hopefully the following presentation shall give an insight into basic welding inspection.
Welding is a fabrication process that lets you join materials like metals by using heat at high temperatures. Welding uses high temperature to join the materials, whereas soldering and brazing do not allow the base metal to melt. After cooling, the base metal and the filler metal get attached.
The welding process came to light when there was a search for the technique for developing iron into useful shapes. Welded blades were the first result of welding in the early years—the carburization of iron produced hard steel that was very brittle for usage. Later interlaying the rigid and soft iron with high-carbon material and hammer forging resulted in a tough and durable blade.
The process of welding uses filler material. The filler material is the pool of molten material that aids in the formation of a strong link between the base metal. The shielding process after welding the metals protects both the base and filler components from being oxidised.
From gas flame to ultrasound, many energies are used in welding like electron beams, electric arc, LASER, and friction. Now let us understand various types of welding.
Types of Welding
There are many types of welding used for various purposes under different situations. They are:
Manual welding includes:
Forge welding
Arc welding
Oxy-fuel welding
Shielded metal arc welding
Gas metal arc welding
submerged arc welding
flux-cored arc welding
electroslag welding
Laser beam welding
electron beam welding
magnetic pulse welding
friction stir welding
Demand of welding increase of new materials.
-- ceramics and metal matrix composites.
-- High strength low-alloy (HSLA) steels
Lack of skilled labours
Traditional welding techniques are costly
Safety concerns.
Need to improve the total cost effectiveness of the welding
Lalit Yadav
An electric vehicle, also called an EV, uses one or more electric motors or traction motors
for propulsion instead of the traditional fossil fuel.
• First electric carriage was built in 1830s and the first electric automobile was built in 1891
in the United States.
• Types : Battery electric Vehicle
Hybrid Electric Vehicle
Plug-in Hybrid Electric Vehicle
Fuel Cell Electric Vehicle
• Electric vehicles will play a pivot role in changing the environment and economy around
the globe in the next two decades.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
3. ALUMINIUM AND ITS ALLOYS
•Melting point of Al 660 C
•Light weight, density is about 1/3 that of steel or copper alloys
•Certain aluminum have a better strength to weight ratio than that of high strength steel
•Have good malleability and formability, high corrosion resistance and high electrical and thermal conductivity.
•An ultra pure form of Al is used as photographic reflectors.
•Non tarnishing characteristics Non toxic, non magnetic, and non sparking Electrical conductivity of the electric conductor
grade is about 62% that of copper.
•Relatively soft and weak.
•Strength can be increased by cold working, alloying and heat treatment.
4. Alloy designation: a four digit number for wrought Al and wrought Al alloys 1XXX, 2XXX, 3XXX, 4XXX,…………, 8XXX
AW 1XXX – commercially pure aluminium.
• AW 2XXX – aluminium–copper alloys.
• AW 3XXX – aluminium–manganese alloys.
• AW 4XXX – aluminium–silicon alloys.
• AW 5XXX – aluminium–magnesium alloys.
• AW 6XXX – aluminium–magnesium–silicon alloys.
• AW 7XXX – aluminium–zinc–magnesium alloys.
• AW 8XXX – other elements e.g. lithium, iron.
• AW 9XXX – no alloy groups assigned.
CAST Aluminium
1XX.X, 2XX.X, ……,8XX.X
Alloying elements in Commercial Al alloys include Cu, Si, Mg, Mn, and occasionally Zn, Ni, and Cr. The alloying
elements may enhance the mechanical properties by
• Solid solution hardening
• Responding to precipitation hardening or
• Strain hardening by cold work
5. Temper designation:
F – as fabricated
O – Annealed, recrystallized
H – Strain hardened
H1 – Strain hardened only
H2 – Strain hardened Then partially annealed
H3- Strain hardened and then stabilized
W – Solution heat treated
•T – thermally treated
•T2 – Annealed ( cast products only)
•T3 – Solution heat treated and then cold
•worked
•T4 – Solution heat treated and naturally aged
•T5 – artificially aged only
•T6 – solution heat treated and then artificially aged
•T7 – Solution heat treated and then stabilized
•T8 – solution heat treated, cold worked and
•then artificially aged
•T9 – Solution heat treated, artificially aged and
•then cold worked
•T10- Artificially aged and then cold worked
6. Filler Metals for Al & Al Alloys
GTAW & GMAW are mostly used.
It depends on
• Base metal composition
• Joint design
• Dilution
• Cracking techdencies
• Strength and ductility requirements
• Corrosion in service
• Appearance
7. Other Factor to be consider in welding Al alloys
•Cleaning of base metal
•Weld backing
•Preheating &
•Tack welding
Cleaning of base metal
•Components for welding may be flat, preformed, sheared, sawn or milled.
•Lubricants, oxides, greases, oils, paints must be removed if weld quality is to be maintained.
•Degreasing may be accomplished by wiping, brushing, spraying or vapour degreasing with commercially
available solvents.
•Scraping is also an excellent method for removing the oxide film.
•Stainless steel wire brushes, stainless steel wire wool or files may also be used to remove the oxide.
8. To achieve freedom from porosity, chemical cleaning or pickling may be required
9.
10. Weld Backing
•Used when full penetration weld
•To controle the amount of reinforcement & shape of the
root surface.
•Temporary Backing
•Permanent Backing
Temporary Backing
Copper, Carbon steel, or stainless steel
Permanent Backing
Al
11.
12. Pre-Heating
Not necessary – increase the width of the HAZ & Reduce the mechanical properties
Sometime higher thickness need pre-heat (<165 C)
If Mg= 3%-5.5% ----- Pre-heat (<120 C) & Interpass temp (<165 C)
Tack Welding
Used to Hold the component parts
To attach tab-in and tab-out
Improper tack weld- Leads to porosity in welds and
incomplete fusion
13. Porosity
Welding Problems
•Porosity- H2 solidification of weld bead
•If in the form of large discontinuous cavities or
long continuous holes - Due to excessive current-
this defects is know as tunneling
In the case of GMAW of aluminum wrought products,
the filler electrode, shielding gas, and base-metal surface
contaminants may contribute to gas porosity.
HYDROGEN SOLUBILITY IN PURE ALUMINUM
14. Cracking
•Solidification cracking
•Liquation cracking
•Stress corrosion cracking
Solidification cracking, or hot tearing, occurs when high levels of thermal stress and solidification shrinkage.
The hot tearing sensitivity of aluminum alloy is influenced by a combination of mechanical, thermal, and metallurgical
factors.
Hot tearing occurs within the weld fusion zone and is affected by weld-metal composition and welding parameters.
High heat inputs, such as high currents and slow welding speeds
It follows that processes that result in minimal heat input, such as electron-beam welding, reduce weld crack sensitivity.
The primary method for eliminating cracking in aluminum welds is to control weld-metal composition through filler
alloy additions.
15. Crack sensitivity, determined experimentally as a function of weld composition, is shown in for various binary aluminum
systems (Al-Li, Al-Si, Al-Cu, Al-Mg, and the quasibinary Al-Mg2Si)
16. Liquation Cracking
An important element of the HAZ for precipitation-hardenable alloys is the thin boundary layer adjacent to
the fusion zone that is referred to as the partially melted region.
This region is produced when eutectic phases or constituents that have low melting points (melting points
below the melting point of the bulk material) liquate, or melt, at grain boundaries during welding
17. Joint Design
Root opening and large groove angle are normally used because Al is more fluid.
V-groove angle – 600 t > 3mm, for higher thickness J-Groove is used.
Electrode selection
W Electrode selected based on the welding current
Pure tungsten (EWP)
Zirconated tungsten (EWZr) Electodes
Thoriated tungsten electrode (EW Th-3)
EW Th -1 or EW Th-2
Used for DC or SWAC
( Both have higher emissivity,
better current carrying capacity and
long life than other electrodes)
Used for conventional AC
(Keep Hemisphere shape)
GTAW of Al alloys
18. Shielding Gas:
Ar is most commonly used shielding gas
Provides better arc starting characteristics than He gas and improve cleaning action
He is used - Machine welding with DCEN power
- Welding at higher speed
- Greater penetration than Ar
He-Ar mixture - 75He-25Ar – higher travel speed
- 90He-10Ar – better arc starting characteristics with DC than pure He
19. Conventional AC (50 HZ)
Ar or Ar-He mixture shielding gas are used
Surface oxide is removed by arc action.
Bright weld bead with silvery border indicates proper gas shielding and arc cleaning
Oxide weld bead – due to unstable arc , low current input, poor shielding gas
or excess arc length
Welding Procedure
Power supplies
I) Conventional AC (50 HZ)
II) DC with electrode negative (DCEN)
III) DC with electrode positive (DCEP)
IV) Square wave AC (SWAC)
20. DC with electrode negative (DCEN)
DCEN power - Advantages than Ac power
(short arc length, thin sections, higher welding speed)
Surface appearance – Dull – due to formation of thin oxides films
(because cleaning action is only done by electrode +ve)
But oxide layer is layer is removed by wire brushing.
Ar shielding gas is used – but penetration is less than He shielding gas
Square groove – used for higher thickness
In V- groove root space is higher than Ac arc weld.
DC with electrode positive (DCEP)
Good surface cleaning action
Section thickness < 1.25mm – because W electrode heating
Ar shield gas is used because He or Ar- He mixture makes electrode over heating
Weld backing are recommended
21. Square wave AC (SWAC)
SWAC – designed to produce a D.C. power with arrangement to rapidly shift the
polarity to produce A.C. waves from the adjustable frequency.
SWAC power – Combines the surface cleaning (AC power) and deep penetration (DCEN)
Ar shielding gas is preferred
Ar- He mixture or He are used were deep penetrations need.
x
22. GMAW of Al alloys
Electrode Feeding
feeding system - Push , Pull or Push-Pull are used depends on wire material and
mode of welding (Semi-Automatic Welding & Automatic Welding)
Shielding gas
Ar -Mostly used for manual welding with
spray type metal transfer.
(Provide excellent arc stability, bead shape ,
and penetration in all weld positions )
He- suitable for Machine and automatic welding
with high current.
He-Ar mixture – instead of He for arc stability provided by Ar
(20%-90% He used)
Increasing in He content – Increase Arc voltage, penetration and spatter
23. Semi-Automatic Welding
GMAW - Arc should be started at a location on the joint that will be melted
into the weld metal.
Arc should not start on the outside of base metal – because the arc strike might
cause surface discontinuity – cause failure at service time.
End of the nozzle – 20mm above the base metal (reduced during Al-Mg alloys to avoid
loss of Mg vaporization )
Short arc – for small fillet weld
Low voltage – cause excessive spatter tends to increase porosity
High voltage – cause incomplete root penetration and contamination of weld metal
So, For first pass low voltage is used and for other passes the higher voltage is used
24. Heat treatable Al Alloys – Stringer bead technique is used and cooled to 650 C between passes with this
Heat input is minimized and HAZ is narrow
Non-Heat treatable Al alloys(5xxx) - welded with larger beads
Biggest dia electrode – section thickness, joint design & welding position
Larger dia electrode – favorable for surface to volume ratio- minimize porosity
Automatic Welding
Higher travel speed than Semi-automatic welding
Longer joints welded without interrupting in welding
This reduce no. of weld craters cracks
Higher current can be used
Square groove – upto 13mm can weld with single pass
25mm can weld with single pass with higher current and large electrode
26. Physical properties of titanium
• Crystal structure
• HCP (<882.5oC)
• BCC (>882.5oC)
• Density (g.cm-3) 4.54
• Melting point - 1667 oC
• Experiences allotropic transformation (α ->β) at 882.5oC.
• Highly react with oxygen, nitrogen, carbon and hydrogen.(Burn in pure O2 at 600oC)
• Difficult to extract & expensive.
• Used mainly in wrought forms for advanced applications where cost is not critical.
• High strength and toughness
28. 1. Commercially pure (CP) titanium
2. Alpha titanium alloys and
3. Near Alpha titanium alloys(Ti-5Al-2.5Sn)
• Generally non-heat treatable and weldable
• Medium strength, good creep strength, good corrosion resistance
4. Alpha-beta titanium alloys(Ti-6Al-4V & Ti-5Al-2Sn-2Zr-4Mo-4Cr)
• Heat treatable, good forming properties
• Medium to high strength, good creep strength
• Weldability depends on beta %, High beat alloy % causes
embrittlement
5. Beta titanium alloys(Ti-13V-11Cr-3Al)
• Heat treatable and readily formable
• Very high strength, low ductility
• Good Weldability at annealed conditions – ageing – high strength
Classification of titanium alloys
29. Alloying system of titanium
Alpha stabilisers
Al, O, N
Beta stabilisers
Mo, V, W, Nb, Ta, Fe, Cr, Cu, Ni, Co, Mn.
Neutrual
Zr, Si, Sn
30. Welding of titanium alloys
• α and α+β titanium alloys are readily weldable.
• β titanium alloys are not readily weldable due to high
amounts of alloying element macro/micro segregation.
• Tungsten Inert Gas Welding
• Electron Beam Welding
• Laser Beam Welding
• Friction welding
31. • Most widely used technique for titanium welding.
• Require no vacuum
• Lower operating cost
• Provide relatively coarser weld structure than those
obtained from EBW and LBW.
• High heat input relatively high distortion.
Tungsten inert gas welding
Arc is produced between a nonconsumable
tungsten electrode and the metals in the presence
of shielding gas (He, Ar).
32. • Electron beam is used as a heat source.
• Vacuum and non-vacuum process clean.
• Relatively high operating cost and equipment.
• Multiple or single -pass arc welding
• Low heat input minimum distortion
Electron beam welding
33. • Laser is used as a heat source.
• Correct choice of shielding gas
• Adequate shielding methods
• Pre-cleaning (de-greasing)
• Good joint surface quality
Laser beam welding
Advantages of laser beam welding
• High productivity (nearly 10 times faster than
TIG).
• Low heat input and therefore low distortion.
• Ease of automation for repeatability.
• No need for filler wire, thus reducing costs
34. Friction welding is carried out by moving one part in a
linear reciprocating motion to effect the heat at the
joint.
• High cost of welding machines.
• Can use to join dissimilar metals.
• Very small distortion.
• Limited to non-round and non-complex component.
Friction welding
35. • Titanium and titanium alloys are highly reactive to oxygen, therefore care
must be taken for titanium welding.
Should be carried out in vacuum or appropriate shielding gas such as Ar or He.
The main defects occur in titanium welding are;
• Weld metal porosity
- Most frequent defects caused by gas bubbles trapped between dendrites
during solidification.
• Embrittlement
- Due to oxygen, nitrogen or hydrogen contamination at T> 500oC. need
effective shielding.
• Contamination cracking
- Due to iron contamination reducing corrosion resistance, separate from steel
fabrication.
Defects in titanium welding
Macroscopic pore observed in TIG
welding of beta titanium alloy
38. Copper And Copper Alloys
• Excellent electrical and thermal conductivities
• Outstanding resistance to corrosion
• Ease of fabrication
• Good strength and fatigue resistance
39. Copper Alloys
• COPPERS, WHICH CONTAIN A MINIMUM OF 99.3% CU
• HIGH-COPPER ALLOYS, WHICH CONTAIN UP TO 5% ALLOYING ELEMENTS
• COPPER-ZINC ALLOYS (BRASSES), WHICH CONTAIN UP TO 40% ZN
• COPPER-TIN ALLOYS (PHOSPHOR BRONZES), WHICH CONTAIN UP TO 10%
SN AND 0.2% P
• COPPER-ALUMINUM ALLOYS (ALUMINUM BRONZES), WHICH CONTAIN UP
TO 10% AL
• COPPER-SILICON ALLOYS (SILICON BRONZES), WHICH CONTAIN UP TO 3% SI
• COPPER-NICKEL ALLOYS, WHICH CONTAIN UP TO 30% NI
• COPPER-ZINC-NICKEL ALLOYS (NICKEL SILVERS), WHICH CONTAIN UP TO
27% ZN AND 18% NI
40. Factors Affecting Weldability
• Effect of Thermal Conductivity.
• Cu has high thermal conductivities
• the type of current and shielding gas must be selected to provide maximum heat
input to the joint
• preheating may be decided based on thickness
• Counteracts the rapid head dissipation
• Cold worked Cu alloys tend to become weaker and softer at HAZ
hot cracking may occur in heavily cold worked
• Welding Position
• highly fluid nature
• flat position is used whenever possible
• Vertical, overhead and the horizontal position- seldom used
41. • Precipitation-Hardenable Alloys
• Beryllium, chromium, boron, nickel, silicon, and zirconium.
• Care must be taken to avoid oxidation and incomplete fusion.
• Reduction in mechanical properties due to overageing
• Should be welded in the annealed condition, followed by precipitation hardening treatment
• Hot Cracking
• copper-tin and copper-nickel, are susceptible to hot cracking
• wide liquidus-to-solidus temperature range
• Severe shrinkage stresses produce interdendritic separation during metal solidification
42. • Porosity
• zinc, cadmium, and phosphorus have low boiling points.
• Vaporization of these elements during welding may result in porosity.
• Higher travel speed and filler metals with less volatile element content
• Surface Condition
• Oxides formed are difficult to remove
• Cleaning and shielding helps to avoid oxide formation
43. Welding of Cu
• Difficulties: High oxygen content and impurities
• Electrode: Ecu and filler: ERCu
• Preheating : thickness, conductivity
46. • GTAW
• Upto 3.2mm thickness but more for flat position
• Shielding: upto 1.6mm Ar and over 1.6mm He, deeper penetration
• Pulsed current can be used
• GMAW
• Shielding: Ar or mixture of Ar and He
• Filler: ERCu
• Spray transfer and pulsed current
• SMAW
• ECuSi, ECuSn-A
• DCEP
• Flat position
47. Other processes for welding of Cu
• Laser beam welding
• Difficulties: high reflection of laser beam and high thermal conductivity
• Absorption increases with temperature
• Shorter wavelength has better welding
• Electron beam welding
• Thin and thick sections
• Resistance spot welding
• Lower conductivity alloys readily spot welded
• Not practical for unalloyed Cu
48. • Flash welding
• Leaded Cu (upto 1% Pb) can be flash welded
• Rapid upsetting at minimum pressure
• Low melting point and narrow plastic range
• Premature termination of current: lack of fusion
• Delayed termination: over heating
• Solid state welding
• Annealed Cu can be welded at room temperature: good malleability
• Diffusion welded or explosive welding
51. Crystal structure FCC
Atomic number 28
Atomic weight 58.71
Density (g.cm-3) 8.89
Melting point (oC) 1455
Nickel and its alloys
Properties
• Silvery shiny appearance
• High toughness and ductility
• Good high and low temperature strength
• High oxidation resistance
• Good corrosion resistance
• Ferro-magnetic
• Relatively high cost
• Not mixed with cheap alloying elements.
52. The defects and metallurgical difficulties encountered in the arc welding of
nickel alloys include:
• Porosity
• Susceptibility to high-temperature embrittlement by sulfur and other
contaminants
• Cracking in the weld bead, caused by high heat input and excessive
welding speeds
• Stress-corrosion cracking in service
Weld Defects in nickel
53. Porosity
Oxygen, carbon dioxide, nitrogen, or hydrogen can cause porosity in welds.
Presence of deoxidizers or nitride-forming elements (aluminum and
titanium) in SMAW and SAW processes type of electrode serves to reduce
porosity.
These elements have a strong affinity for oxygen and nitrogen and form
stable compounds with them.
54. Cracking
Hot cracking of welds can result from contamination by sulfur, lead, phosphorus, cadmium, zinc, tin, silver,
boron, bismuth, or any other low-melting-point elements, which form intergranular films and cause severe
liquid-metal embrittlement at elevated temperatures.
Cracking in the heat-affected zone is often caused by intergranular penetration of contaminants from the base-
metal surface. Sulfur, which is present in most cutting oils used for machining, is a common cause of cracking in
nickel alloys. The removal of foreign material from the surfaces of the work metal is imperative.
Weld metal cracking also can be caused by heat input that is too high, as a result of high welding current and
low welding speed. Welding speeds have a large effect on the solidification pattern of the weld. High welding
speeds create a tear-drop molten weld pool, which leads to uncompetitive grain solidification at the center of
the weld. At the weld centerline, residual elements will collect and cause centerline hot cracking or lower
transverse tensile properties.
In addition, cracking may result from undue restraint. When conditions of high restraint are present, as in
circumferential welds that are self restraining, all bead surfaces should be slightly convex. Although convex
beads are virtually immune to centerline splitting, concave beads are particularly susceptible to centerline
cracking. In addition, excessive width-to depth or depth-to-width ratios can result in cracking that may be internal
(that is, subsurface cracking).
55. Stress-Corrosion Cracking
When the alloys are intended to contact substances such as concentrated caustic
soda, fluorosilicates, and some mercury salts,
The welds may need to be stress relieved to avoid stress-corrosion cracking.
Effect of Slag on Weld Metal
If slag is not removed in the latter type of application, then crevices and
accelerated corrosion can result.
Slag inclusions between weld beads reduce the strength of the weld.
Fluorides in the slag can react with moisture or elements in the environment to
create highly corrosive compounds.