This document discusses the effect of nanophase precipitates on the nucleation of intragranular ferrite in microalloyed steel. It finds that MnS and MnS+V(C,N) complex precipitates provide nucleation centers for intragranular ferrite, leading to grain refinement. Heavy deformation of austenite at low temperatures increases substructures in austenite, causing V(C,N) nanophase to precipitate at these substructures and pin them. The substructures then transform into ultra-fine ferrite grains. Precipitate sizes of 20-50nm provided the best nucleation for intragranular ferrite.
Dislocation and twin substructure evolution during strain hardening of an Fe–22 wt.% Mn–0.6 wt.% C TWIP steel observed by electron channeling contrast imaging
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Dislocation and twin substructure evolution during strain hardening of an Fe–22 wt.% Mn–0.6 wt.% C TWIP steel observed by electron channeling contrast imaging
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Microstructural Characterization of Co-Cr-Mo-W Alloy as Casting for Odontolog...IJERA Editor
Interest in the analysis and material characterization is rising due to the necessity of the adequate material selection based on system performance in study. The analysis and knowledge of the microstructure and the mechanical properties of any material are of utmost importance since it aims primarily to estimate the performance during the material life span, minimizing the possibility of degradation and undesirable flaws during product utilization. Co-Cr-Mo-W alloys have been well accepted in odontology as prosthesis material, due to its high mechanical resistance, good corrosion resistance and exceptional biocompatibility properties. This study aims to characterize the microstructure of a cobalt based alloy (Co-Cr-Mo-W) obtained through vacuum casting process. Optical microscopy, electronic sweeping microscopy and X-ray were employed and Vickers hardness test with loads of 100 gf, 500 gf and 1000 gf during 10 s. Microstructure casting is characterized by a Co-fcc dendritic matrix with a secondary phase, as well as M23C6 precipitate carbides in the interdendritics zones and grain boundaries. The precipitation of carbides represents the main device of strengthening in the cast state for these types of alloys and is also responsible for its lower mechanical properties. The material attained hardness between 25 and 35 HRC, meeting the ASTM F75 standards.
Influence of phase transformation on the work hardening characteristics of Pb...iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Preparation and Investigation on Properties of Cryogenically Solidified Nano ...IJERA Editor
In the present work, AL-alloy containing 12% silicon (LM 13) matrix nano composites were fabricated in sand moulds by using copper end blocks of copper end chill thickness 10 &15 nm with cryogenic effect . The size of the reinforcement (NanoZro2) ranges from 50-80nm being added ranges from 3 to 15 wt % in steps of 3 wt % . Cryogenically solidified Nano Metal Matrix Composites were compressed by using hydraulic compression machine. Specimens were prepared according to ASTM standards and tested for their strength, hardness and fracture toughness. Micro structural studies of the fabricated Nano Composites indicate that there is uniform distributions of reinforcements in the matrix materials (LM 13). An increasing trend of hardness, UTS & fracture toughness has been observed. The best results have been obtained at 12 wt %. The results were further justified by comparing two copper end chill thickness 10 &15 mm. Finally the Volumetric Heat Capacity of the cryo-chill is identified as an important parameter which affects mechanical properties.
Magneto-transport properties of MnGeP2 and MnGeAs2 filmsIJERA Editor
MnGeAs2 and MnGeP2 thin films were deposited on GaAs and Si substrates. For these film samples, roomtemperature ferromagnetism was observed from magnetization and resistance measurements and verified from hysteresis in magnetization measurements. Hysteresis as well as anomalous behavior in Hall effect measurements was found in the deposited MnGeAs2 and MnGeP2 films, implying spin polarization of the mobile carriers in the films. The Hall resistance measurements above the ferromagnetic transition temperature showed that the carriers are n-type in MnGeAs2 and p-type in MnGeP2.
Modeling and finite element analysis for a casting defect in thin wall struct...Dr.Vikas Deulgaonkar
The casting of pump impeller blades is a difficult operation due to its thin wall structure. In the casting process for thin wall impeller structure, the prediction of shrinkage defect is a one of the important issue and failure of such thin wall structure is a commonly encountered problem. The non-uniform heat transfer rate is the main cause of such failure. The uniformity of heat transfer rate may enhance by placing the runner at appropriate position and riser based on the geometrical attributes. The flow of liquid metal and its solidification has time based temperature variation, shrinkages and porosity distributions in such structures. An attempt is made for the analysis of optimization in the placement of runner and riser through this experimentation. The experiment contains the analysis of finite element simulation of fluid flow and solidification of metal execution at various temperatures, prediction of shrinkages based on the geometry of the casting and flow curvature and porosity distribution. This work also focuses on the prediction of casting defects in aluminum thin wall pump impeller structure using commercially available software (ANSYS-FLUENT). The experimental validation of the simulation result is also done to confirm the same.
Influence of Ruthenium doping on Structural and Morphological Properties of M...IJERA Editor
The present work examines the effect of Ru doping on MoO3 thin films on steel substrate deposited by Sol-gel spin coat method. The annealing temperature was 6000C for pure MoO3 and 8000C for Ru doped thin films. The doping concentration of Ru was varied from 10 to 50wt%. The influence of Ru doping on structural and morphological properties of MoO3 thin films were studied. The XRD revealed that all films are highly crystalline in nature with monoclinic phase for molybdenum peaks. In the doped XRD pattern some new peaks were observed and are matched with ruthenium orthorhombic phase indicating an incorporation of dopant in pure molybdenum oxide. The same is confirmed with the compositional analysis by EDAX. The SEM images of the MoO3 resemble a rod like surface with porous morphology. Incorporation of Ru ions in molybdenum oxide decreases the length of the rods and vanishes after 40wt%. Tetragonal grain size increases from 20wt% of Ru and becomes maximum at 50wt% of Ru doped thin films
Investigation of the distribution of lead in three different combinations of ...Rautomead Limited
The main objective of this paper was to assess three leaded
brass samples (pending application with Copper Development
Association) using optical microscopy and mass
spectrometry to compare the distribution of lead. Based on
the mass spectrometry data, a great deal of variation was
not found within each of the samples based on five different
sample locations. Optical microscopy, scanning electron
microscopy and energy-dispersive X-ray spectroscopy
confirmed that the lead was homogenously distributed in
brass.
Characteristics of Hypoeutectic Cu-Zr Alloy Rods Manufactured by Vertical Upw...Rautomead Limited
The focus in this study is therefore on applying a vertical upwards continuous casting (VUCC) mass-production
method to the pilot-scale manufacturing of Cu-Zr alloy rods. The microstructure and physical characteristics of these
VUCC rods were subsequently investigated and compared with rods produced by CMC. In addition, the wire-drawing
capability of the VUCC rods was examined, and the adaptability of the VUCC method to the mass production of
hypoeutectic Cu-Zr alloys was fully investigated.
2.
Microstructure Degradation after Prolonged Exploitation of Heatresistant Ste...IJMER
Metallographic testing of material microstructure represents important method for
characterization of material behavior. In case of heat resistant steels that are used for steam lines and
boiler components of thermal power plants for a long period of service time, under the influence of
mechanical and thermal loads their microstructure will be changed. As a result, it will have significant
influence on mechanical properties of such material. Metallographic testing can be used for following
of microstructure evolution
and estimation of components further safe service time, but at the same time knowing of changes in
material microstructure is necessary for better understanding of mechanical properties degradation
mechanism. Microstructure as indicator of material degradation of heat resistant streamline steel
14MoV6-3 after almost 200.000 hours of exploitation at steam temperature 540 °C and pressure
13,5MPa has been investigated in this paper. It is necessary to emphasize that this streamline has been
designed for service life time of 100.000 hours for mentioned steam parameters.
Microstructural Characterization of Co-Cr-Mo-W Alloy as Casting for Odontolog...IJERA Editor
Interest in the analysis and material characterization is rising due to the necessity of the adequate material selection based on system performance in study. The analysis and knowledge of the microstructure and the mechanical properties of any material are of utmost importance since it aims primarily to estimate the performance during the material life span, minimizing the possibility of degradation and undesirable flaws during product utilization. Co-Cr-Mo-W alloys have been well accepted in odontology as prosthesis material, due to its high mechanical resistance, good corrosion resistance and exceptional biocompatibility properties. This study aims to characterize the microstructure of a cobalt based alloy (Co-Cr-Mo-W) obtained through vacuum casting process. Optical microscopy, electronic sweeping microscopy and X-ray were employed and Vickers hardness test with loads of 100 gf, 500 gf and 1000 gf during 10 s. Microstructure casting is characterized by a Co-fcc dendritic matrix with a secondary phase, as well as M23C6 precipitate carbides in the interdendritics zones and grain boundaries. The precipitation of carbides represents the main device of strengthening in the cast state for these types of alloys and is also responsible for its lower mechanical properties. The material attained hardness between 25 and 35 HRC, meeting the ASTM F75 standards.
Influence of phase transformation on the work hardening characteristics of Pb...iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Preparation and Investigation on Properties of Cryogenically Solidified Nano ...IJERA Editor
In the present work, AL-alloy containing 12% silicon (LM 13) matrix nano composites were fabricated in sand moulds by using copper end blocks of copper end chill thickness 10 &15 nm with cryogenic effect . The size of the reinforcement (NanoZro2) ranges from 50-80nm being added ranges from 3 to 15 wt % in steps of 3 wt % . Cryogenically solidified Nano Metal Matrix Composites were compressed by using hydraulic compression machine. Specimens were prepared according to ASTM standards and tested for their strength, hardness and fracture toughness. Micro structural studies of the fabricated Nano Composites indicate that there is uniform distributions of reinforcements in the matrix materials (LM 13). An increasing trend of hardness, UTS & fracture toughness has been observed. The best results have been obtained at 12 wt %. The results were further justified by comparing two copper end chill thickness 10 &15 mm. Finally the Volumetric Heat Capacity of the cryo-chill is identified as an important parameter which affects mechanical properties.
Magneto-transport properties of MnGeP2 and MnGeAs2 filmsIJERA Editor
MnGeAs2 and MnGeP2 thin films were deposited on GaAs and Si substrates. For these film samples, roomtemperature ferromagnetism was observed from magnetization and resistance measurements and verified from hysteresis in magnetization measurements. Hysteresis as well as anomalous behavior in Hall effect measurements was found in the deposited MnGeAs2 and MnGeP2 films, implying spin polarization of the mobile carriers in the films. The Hall resistance measurements above the ferromagnetic transition temperature showed that the carriers are n-type in MnGeAs2 and p-type in MnGeP2.
Modeling and finite element analysis for a casting defect in thin wall struct...Dr.Vikas Deulgaonkar
The casting of pump impeller blades is a difficult operation due to its thin wall structure. In the casting process for thin wall impeller structure, the prediction of shrinkage defect is a one of the important issue and failure of such thin wall structure is a commonly encountered problem. The non-uniform heat transfer rate is the main cause of such failure. The uniformity of heat transfer rate may enhance by placing the runner at appropriate position and riser based on the geometrical attributes. The flow of liquid metal and its solidification has time based temperature variation, shrinkages and porosity distributions in such structures. An attempt is made for the analysis of optimization in the placement of runner and riser through this experimentation. The experiment contains the analysis of finite element simulation of fluid flow and solidification of metal execution at various temperatures, prediction of shrinkages based on the geometry of the casting and flow curvature and porosity distribution. This work also focuses on the prediction of casting defects in aluminum thin wall pump impeller structure using commercially available software (ANSYS-FLUENT). The experimental validation of the simulation result is also done to confirm the same.
Influence of Ruthenium doping on Structural and Morphological Properties of M...IJERA Editor
The present work examines the effect of Ru doping on MoO3 thin films on steel substrate deposited by Sol-gel spin coat method. The annealing temperature was 6000C for pure MoO3 and 8000C for Ru doped thin films. The doping concentration of Ru was varied from 10 to 50wt%. The influence of Ru doping on structural and morphological properties of MoO3 thin films were studied. The XRD revealed that all films are highly crystalline in nature with monoclinic phase for molybdenum peaks. In the doped XRD pattern some new peaks were observed and are matched with ruthenium orthorhombic phase indicating an incorporation of dopant in pure molybdenum oxide. The same is confirmed with the compositional analysis by EDAX. The SEM images of the MoO3 resemble a rod like surface with porous morphology. Incorporation of Ru ions in molybdenum oxide decreases the length of the rods and vanishes after 40wt%. Tetragonal grain size increases from 20wt% of Ru and becomes maximum at 50wt% of Ru doped thin films
Investigation of the distribution of lead in three different combinations of ...Rautomead Limited
The main objective of this paper was to assess three leaded
brass samples (pending application with Copper Development
Association) using optical microscopy and mass
spectrometry to compare the distribution of lead. Based on
the mass spectrometry data, a great deal of variation was
not found within each of the samples based on five different
sample locations. Optical microscopy, scanning electron
microscopy and energy-dispersive X-ray spectroscopy
confirmed that the lead was homogenously distributed in
brass.
Characteristics of Hypoeutectic Cu-Zr Alloy Rods Manufactured by Vertical Upw...Rautomead Limited
The focus in this study is therefore on applying a vertical upwards continuous casting (VUCC) mass-production
method to the pilot-scale manufacturing of Cu-Zr alloy rods. The microstructure and physical characteristics of these
VUCC rods were subsequently investigated and compared with rods produced by CMC. In addition, the wire-drawing
capability of the VUCC rods was examined, and the adaptability of the VUCC method to the mass production of
hypoeutectic Cu-Zr alloys was fully investigated.
2.
Microstructure Degradation after Prolonged Exploitation of Heatresistant Ste...IJMER
Metallographic testing of material microstructure represents important method for
characterization of material behavior. In case of heat resistant steels that are used for steam lines and
boiler components of thermal power plants for a long period of service time, under the influence of
mechanical and thermal loads their microstructure will be changed. As a result, it will have significant
influence on mechanical properties of such material. Metallographic testing can be used for following
of microstructure evolution
and estimation of components further safe service time, but at the same time knowing of changes in
material microstructure is necessary for better understanding of mechanical properties degradation
mechanism. Microstructure as indicator of material degradation of heat resistant streamline steel
14MoV6-3 after almost 200.000 hours of exploitation at steam temperature 540 °C and pressure
13,5MPa has been investigated in this paper. It is necessary to emphasize that this streamline has been
designed for service life time of 100.000 hours for mentioned steam parameters.
A non-surgical rhinoplasty or non-surgical nose job uses injection of safe and effective filler materials (typically Radiesse) to alter the shape of the nose. Non-surgical rhinoplasty is a quick and easy alternative for those who want to improve certain features of their nose but are not yet ready for a surgical rhinoplasty. Non-surgical rhinoplasty takes less than five minutes to perform and has minimal discomfort and minimal recovery associated with it. Results typically last up to one year. Non-surgical rhinoplasty should ideally be performed by a surgeon who is also experienced in surgical rhinoplasty.
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.
Fabrication and Study of the Mechanical Properties of AA2024 Alloy Reinforced...IOSR Journals
Metal matrix nanocomposites (MMNCs) with the addition of nano-sized ceramic particles can be of
significance for automobile, aerospace and numerous other applications. The physical and mechanical
characteristics of the light refractory carbides such as SiC, TiC and B4C make them suitable for being used as
reinforcement in aluminium base metal matrix composites This paper presents a technique for an inexpensive
fabrication of bulk lightweight MMNCs with reproducible microstructures and superior properties by use of
ultrasonic nonlinear effects, namely transient cavitation and acoustic streaming; to achieve uniform dispersion
of nano-sized B4C particles in molten aluminum alloy. Nano-sized B4Cp enhanced properties of aluminium
matrix composites, with 1.5%wt of B4C. As compared to the base metal alloy, the mechanical properties
including tensile strength and yield strength of the nanocomposites were improved significantly, while the
ductility of base metal alloy matrix castings was retained. Micro structural study was carried out with an
optical microscope and SEM which validates a good dispersion of nano-sized B4Cp in metal matrix. Mechanical
properties of the as-cast MMNCs have been improved significantly even with a low weight fraction of nanosized
B4C.
STRUCTURE PROPERTY CORRELATION OF MODIFIED Al-Mg ALLOYS FOR AEROSPACE APPLICA...sivanagaraju chittelu
Making a new metal for Aerospace applications which is made of many components .Major metals are Aluminium and Magnesium.Checking its structures and properties .
Characterization of Manganese doped ZnO (MZO) thin films by Spin Coating Tech...IOSR Journals
Doping is a widely used to improve the structural and optical properties of semiconductors. However deposition route is also very important to get nanostructure with different properties. ZnO nanostructures doped with Mn having 5% doping concentrations by weight percentage have been synthesized in the laboratory using Spin coating technique. Scanning Electron Microscope (SEM) image shows the around one millimeter and X-ray diffractometer studies shows that the average diameter of the particles is 25 nm. From the UV-Vis studies the annealing temperature increases the crystal size decreases and the bandgap values increases accordingly.
Effect of Adding Indium on Wetting Behavior, Microstructure and Physical Prop...Editor IJCATR
Effect of adding indium on microstructure, wetting process, thermal, electrical and mechanical properties of tin- zinc eutectic alloy
have been investigated. Microstructure (started base line, lattice parameters, unit cell volume, crystal size and the shape of formed crystalline
phases) and measured physical properties of tin- zinc eutectic alloy changed after adding different ratio of indium content. A little variation
occurred in thermo-graph (Endo-thermal peaks) of Sn91Zn9 alloy after adding indium. The contact angle, melting temperature and specific heat of
Sn91Zn9 alloy decreased after adding indium content. Also elastic modulus and internal friction values of Sn91Zn9 alloy decreased after adding
indium content. But electrical resistivity and Vickers hardness values of Sn91Zn9 alloy increased after adding indium content. The SnZn9In5 alloy
has adequate properties for solder applications.
Effect of Adding Indium on Wetting Behavior, Microstructure and Physical Prop...Editor IJCATR
Effect of adding indium on microstructure, wetting process, thermal, electrical and mechanical properties of tin- zinc eutectic alloy have been investigated. Microstructure (started base line, lattice parameters, unit cell volume, crystal size and the shape of formed crystalline phases) and measured physical properties of tin- zinc eutectic alloy changed after adding different ratio of indium content. A little variation occurred in thermo-graph (Endo-thermal peaks) of Sn91Zn9 alloy after adding indium. The contact angle, melting temperature and specific heat of Sn91Zn9 alloy decreased after adding indium content. Also elastic modulus and internal friction values of Sn91Zn9 alloy decreased after adding indium content. But electrical resistivity and Vickers hardness values of Sn91Zn9 alloy increased after adding indium content. The SnZn9In5 alloy has adequate properties for solder applications.
Study on Processing and Mechanical Properties of nano SiCp reinforced AA7075theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Theoretical work submitted to the Journal should be original in its motivation or modeling structure. Empirical analysis should be based on a theoretical framework and should be capable of replication. It is expected that all materials required for replication (including computer programs and data sets) should be available upon request to the authors.
The International Journal of Engineering & Science would take much care in making your article published without much delay with your kind cooperation
The objective of this paper is to study the micro
structural features of ZA27alloy containing nickel in the range
from 1 to 3 wt. %. The microstructure of the alloy was examined
using both optical and SEM. High percentage of nickel helps in
imparting strength to the alloy and also to overcome dimensional
instability as it forms various intermetallic compounds containing
hard particles. Small percentage of magnesium in the alloy helps
in reducing intergranular corrosion. The microstructure consists
of small, flaky and rod like irregularly shaped intermetallic
compound in the interdendritic and eutectic regions.
Metallographic studies showed that addition of nickel resulted in
microstructural modifications of the alloy involving the
formation of complex intermetallic compounds α.
Influence of volume fraction, size, cracking, clustering of particulates and ...eSAT Journals
Abstract
The objective of this study is to examine the influence of volume fraction, size of particulates, formation of precipitates at the
matrix/particle interface, particle cracking, voids/porosity, and clustering of particulates on the strength and stiffness of
6063/SiCp metal matrix composites. Tensile strength and stiffness increase with an increase in the volume fraction of SiC
particulates. The tensile strength and stiffness decrease with increase in size of the particulates, presence of porosity, clustering,
and particle cracking. Formation of particulate clusters is more prominent in the composites having very small-reinforced
particulates. Mg2Si compound is likely to precipitate at the matrix/particle interfaces of 6063/SiC composite.
Keywords: 6063, SiC, clustering, cracking, porosity, clustering
Enhanced field electron emission of flower like zinc oxide on zinc oxide nano...Suhufa Alfarisa
For the first time, zinc oxide (ZnO) nanoflowers on ZnO nanorods were produced on carbon nanotubes
(CNTs) synthesised from waste cooking palm oil precursor. First, CNTs were grown using thermal chemical vapour deposition method. Next, ZnO nanostructures were deposited using the sonicated sol-gel immersion method
Micro Structure Amd Mechanical Properties of Nanoparticulate Wc/Al Metal Matr...IJRES Journal
The addition of reinforcement definitely changes mechanical behaviour of metal matrix composites (MMCs). Hence the objective of the work is to study the effect of nano WC particle content on the mechanical behaviour of Al alloy reinforced composites was studied by using optical microscopy, mechanical properties measurements and scanning electron microscope. The hardness, ultimate tensile strength, compression strength and young's modulus were found higher than those of control alloy. The dislocations which serve as heterogeneous nucleation sites for strengthening precipitates during subsequent solidification compared to control alloy. Higher density of dislocations and higher density of intermediate precipitates was observed.
Historical analysis of metal cutting shows that metal removal rates have been increasing in the course of the century, predicated by the advancement in tool materials but the steel design has lagged behind. This paper examines the mechanisms of chip formation and tool wear as a function of cutting speed in metal cutting. Chemical wear is identified as the dominant mechanism of tool wear at high cutting speeds caused by temperature rise due to shear localisation in the primary and secondary shear zones of chip. Shear localisation in the primary shear zone is shown to be influenced by both microstructural parameters, i.e. matrix hardening and second phase particles, and metal cutting variables, i.e. cutting speed (strain rate) and feed (pressure).
Potentiostatic Deposition of ZnO Nanowires: Effect of Applied Potential and Z...IJRES Journal
In this work we report on potentiostatic deposition of Zinc oxide (ZnO) nanowires on fluorine-doped tin oxide (FTO) covered glass substrates from electroreduction of molecular oxygen. The influence of applied deposition potential, and the concentrations of zinc precursor (ZnCl2) on the properties of ZnO nanowires was investigated.SEM results revealed that ZnO nanowires electrodeposited at applied potential -0.85Vhave high density and good alignment. The diameters and densities of the electrodeposited ZnO nanowires are strongly dependent on the zinc ion concentrations and well aligned nanowires with uniform diameter can be obtained when the concentration of zinc ions is between 0.5 mM and 1 mM.
Similar to Effect of Nanophase on the Nucleation of Intragranular Ferrite in Microalloyed Steel.PDF (20)
2. Journal of Wuhan University of Technology-Mater. Sci. Ed. Apr.2010 229
Table 1 The Ae3, Ar3 and chemical composition of the test steels/%
Single-pass compression test were proceeded on a Glee-
ble-2000 thermal simulator. Specimens were austenitized at
1200 ℃for 5 min to make sufficient solutionizing of vana-
dium, followed by cooling at cooling rate of 10 ℃/s and then
deformed throughout undercooled austenite range. Deforma-
tion temperature(T) were 800 ℃(Ae3)-750 ℃(Ar3), deforma-
tion amount(ε) were30%, 50%, 60% and 70%, respectively,
and the rate of deformation were 50 s
-1
.The influences of
static recovery and recrystallization on ferrites were eliminated
by water quenching to room temperature immediately after
deformation.
Microstructure observation was performed by a
scanning and transmission electron microscope (SEM
and TEM), respectively. For SEM observations, 2%-4%
nital was used for etching. TEM thin foil specimens
were prepared by mechanical thinning followed by
twin-jet reduction method. TEM observation was per-
formed by using a JEM-2010 UHR electron microscope.
MnS and V(C, N) particles and structure components in
microstructure were analyzed by a SISC-IAS8.0 image
analysis software. There are few particles which sizes
are greater than 100 nm, so the particles less than 100
nm are regarded as nanaphase. The average sizes of
particles that make up 60% of the precipitation were
used as the grain size of nanophase, ensuring that it was
representative.
3 Results and Discussion
3.1 Nucleation promote effect of MnS and
MnS + V(C, N) on IGF
MDCSobral and GMiyamoto’s work[3,4]
shown that
use metallic oxide as nucleating center, MnS+V(C, N)
complex precipitate can promote the nucleation of intra-
granular ferrite idiomorphs on it. Fig.1 (a) and (b) are
respectively micrograph and EDS of intragranular ferrite
formed on single MnS phase of the non-vanadium test
steel A in Table 1. Fig.1 (c) shows that intragranular
ferrites nucleate on precipitates which are presumably
incoherent MnS+V(C, N). EDS measurement (Fig.1 (d))
reveals that this complex precipitate is V(C, N) precipi-
tated on incoherent MnS in austenite.
Random selected 62 incoherent MnS in austenite of
test steel B and C in Table 1 were investigated to explore
the nucleating effect of MnS and MnS+V(C, N) com-
plex precipitates on intragranular ferrite. Table 2 shows
analyzing result of IGF nucleating rate on MnS and MnS+
V(C, N) precipitates.
Results in Table 2 show that intragranular ferrite
nucleating rate of MnS+V(C, N) complex precipitates is
higher than that of single MnS obviously. These results
show that the nucleating mechanisms of MnS and MnS+
V(C, N) on intragranular ferrite are difference. Manga-
nese is austenite stabilizer; manganese-poor area exists
around MnS increased driving force of γ/α transfor-
mation, thus promote ferrite nucleate on MnS and then
growing into intragranular ferrite. However, compared
with epitaxial growth ferrite on MnS+V(C, N) complex
precipitates, the promotion effect on form new phase of
constitutional supercooling caused by manganese-poor is
very small. Fig.2 shows EDS measurement of
un-nucleated MnS in austenite. It reveals that their exist
higher ferrite peak in MnS. So it can be inferred that this
kind of precipitate constitute by (MnFe)S which belongs
to atypical MnS precipitates. The constitutional super-
cooling degree around (MnFe)S can not satisfy the re-
quest of form new precipitate.
Steel C Si Mn S P V N Ae3/℃ Ar3/℃
A
B
C
0.086
0.091
0.089
0.16
0.18
0.20
0.57
0.56
0.58
0.007
0.005
0.006
0.011
0.0089
0.0094
—
0.064
0.14
0.0032
0.0031
0.0063
862
866
873
718
705
695
Table 2 IGF nucleating rate on MnS and MnS+V(C, N) in test steel B and C
MnS/
MnS+V(C,N)
Nucleated MnS/
analyzed MnS
Nucleated MnS+V(C, N)/
analyzed MnS+V(C, N)
Nucleating rate of MnS
Nucleating rate of
MnS+V(C, N)
22/40 14/22 33/40 63.6% 82.5%
Fig.1 TEM and EDS of MnS and MnS+V(C, N)
3. Vol.25 No.2 LI Xincheng et al: Effect of Nanophase on the Nucleation…230
Statistical analysis on MnS precipitates show that it
also has relationship with the size of MnS whether MnS
could be a nucleating center for intragranular ferrite. The
present work observed that the MnS precipitates size
greater than 100 nm cannot be nucleating center of IGF,
those IGF nucleating centers are all belongs to nanophase
(size less than 100 nm). This is because the differences of
precipitation temperature affect grain size of MnS as well
as the probability to be nucleating center of intragranular
ferrite. The solubility product[9]
of MnS in δ and γ
shows in formula (1) and formula (2).
(1)
(2)
Precipitation temperature (1200 ℃-1390 ℃) of
MnS can be inferred from formula (1) and (2). It means
MnS precipitate in austenite after γ/α transformation.
Most of MnS precipitate on grain boundary of austenite
and growing into large grains (200 nm-300 nm) rapidly,
which not belongs to nanophase. It can not satisfy the
request nanophase grain sizes of intragranular ferrite
nucleating center.
The Refs.[9,10] revealed that the diffusion of man-
ganese was controlling factor for precipitate growth of
MnS, which is because the diffusion coefficient of
manganese in γ is much smaller than sulphur. Diffu-
sion speed of manganese get slow following the decrease
of temperature. The residual manganese and sulfur con-
tents will nucleate on oxide inclusions or high-energy
deformation band formed in austenite granular. At this
point, MnS has no growing tendency. The sizes of MnS
are very tiny, many are the circular nanometer, and it may
become IGF nucleating center.
3.2 Effects of deformed austenite and V(C,
N) on IGF
By analyzing the test steel B in Table 1, the results
shows that partial of ultra-refined ferrite formed in
V-microalloyed steel are caused by heterogeneous nu-
cleation effect of deformation enhanced precipitates in
austenite on intragranular ferrite. A noticeable phe-
nomenon shows that new secondary nucleating ferrite
which have no correlations with precipitates were ob-
served that exist around ultra-refined ferrite nucleated by
precipitates (shows in Fig.3). Actually, the amount and
volume ratio of precipitates are obviously inadequate if
only consider ferrite grains nucleated by precipitates to
make up whole microstructure of ultra-refined steels. The
experimental results inferred that whole microstructure
consists of secondary nucleating ferrite and ultra-refined
ferrites formed by ferrite (second nucleation) dynamic
recrystallization and other unknown grain refining
mechanism.
3.2.1 Effect of deformed austenite fragmentation on IGF
That can be presumed that unknown grain refining
mechanism have relationship with structure evolution of
deformation austenite. High density dislocation relaxa-
tion caused by deformation in austenite made the poly-
gonization of austenite grain, thus refined the grain size
furthermore. There were cellular structures which were
divided by the dense dislocated walls formed in the aus-
tenite. Deformed austenite grains were divided into sub-
grains which has the minimum misorientation by dislo-
cated walls. As deformation carried on, γ/α trans-
formation in austenite subgrains continued, and the aus-
tenite grains were refined. The more deformation of
specimens, the thinner of austenite grains and subgrains.
For that, the size of ferrite grains decreased obviously.
The misorientation of austenite subgrains caused by ro-
tation of austenite grain in the process of deformation
increased as the increasing of deformation amount. In
subsequent process of quenching, ferrite grains were
refined furthermore for there was orientation relation-
ship[11]
between the ferrite and the austenite matrix.
lg[Mn][S] 9090 / 2.929 ( 215 / 0.097)
[Mn] 0.07[Si]
T T= − + − − +
−
lg[Mn][S] 105900 / 4.2489 0.07[Si]T= − + −
Fig.2 EDS of un-nucleated MnS in austenite
Fig.3 Microstructure of test steel B in Table 1
4. Journal of Wuhan University of Technology-Mater. Sci. Ed. Apr.2010 231
Fig.4 shows the shape of cellular structures in aus-
tenite grains of test steel B in table 1 after 30% and 70%
compression deformation respectively at 750 ℃. Fig.4 (a)
shows that the size of cellular structure was uneven and
its shape varied not only massive but also strip, it inferred
that the deformations of austenite grains were severe
inequality. Its microstructure also exists a very serious
phenomenon of mixed crystal, grain size of ferrite were
uneven (2-9 μm), volume ratio of ultra-fine ferrite was
only 10%. Cellular structures in Fig.4 (b) are small and uni-
form, ferrite grain size was only 2.4 μm in its microstructure
anda volume ratio of ultra-fine ferrite was morethan 80%.
3.2.2 Effects of V(C, N) precipitated in austenite on IGF
Precipitation occurred in the grain boundary, the
sub-grain boundaries, dislocation lines, and the disloca-
tion cell wall of austenite in the process of deformation
enhanced transformation. This is because there exist
higher energy than average free energy on austenite ma-
trix at those defects. In addition, the micro-alloy solute
and C, N solute atoms themselves easy-to-segregate at
these defects, and thus in favor of forming nucleating
center for micro-alloy carbon and nitrogen compounds in
these places. Fig.5 shows the shape of precipitation in the
grain boundary, the sub-grain boundaries, dislocation
lines, the dislocation cell wall and α phase of test steel
B and C in Table 1 after 60% compression deformation.
Fig.4 Microstructure of B test steel in Table 1 after
30% and 70% deformation at 800 ℃
Fig.5 Microstructure of precipitation in different defects of test steel B and C after different deformation (50%-70%) at 750℃
5. Vol.25 No.2 LI Xincheng et al: Effect of Nanophase on the Nucleation…232
Fig.5 (a) shows acicular ferrite precipitated in the
grain boundary of austenite. Such ferrites had fuzzy in-
terface, non-axis and irregular-shaped grains, its grain
size were tinier than common transformation ferrite. It
split the original austenite grains, and then limited the
growth of transformation ferrite. As a result, the
pre-generated acicular ferrite had a significant promoting
effect on obtaining fine-grained ferrite in the continuous
cooling process.
Fig.5 (f) shows that two kinds of precipitation were
observed in the same austenite grain. A was intragranular
ferrite precipitate in grain boundary and grown into
transgranular (grain inner). B was precipitation in dislo-
cation cell wall which stabilized the strip dislocation cell
wall where it was precipitated. As sub-structures of aus-
tenite recovery and transformed into ultra-fine grains,
disperse precipitation of nanophase can prevent the
coarsening of ferrite grain.
V(C, N) precipitated in defects of the grain bound-
ary, the sub-grain boundaries, dislocation lines, and the
dislocation cell wall had its special pinning effects on
refine grains. Austenite sub-structure were spun by V(C,
N) precipitates and limited to grown up after it trans-
formed into ferrite. Fig.6 shows that V(C, N) precipitates
have significant spinning effects.
It can be inferred from Fig.6 that the size of trans-
formation ferrite in three test steels were very tiny (less
than or equal 4 μm). Arguably the coarsening driving
force should be very large, but the experimental results
shown that the coarsening ratio of ferrite grain in test
steel C was sluggish. Growing from 2.8 μm to 4 μm
holding for 300 seconds, its growth rate G was about
0.004 μm/s. But at the same experiment condition, the
size of ferrite grain in non-vanadium test steel A was
growing from 3.8μm to 7.4 μm, its growth rate G was
about 0.012 μm/s, about 3 times than test steel C. The
growth rate of test steel B between it of test steel A and C.
As shown in Fig.6, the higher the amount of vanadium,
the more stable of the size of transformation ferrite. The
significant differences of grain growing trend between tree
test steels were due to the differences of micro-precipitation
mechanism of vanadium content in steels.
MNiikura[12]
discussed the effect of microalloy
element vanadium in steel by the first-principles of
quantum mechanics. The segregation energy of vana-
dium on fcc ferrite grain boundary was about 2.35 eV, as
well as its impurity formation energy in crystal was about
0.96 eV. Therefore in the austenite, vanadium can present
in the crystal boundary may also exist in transgranular,
and occupy the crystal boundary. That was, regarded
from energy point, adding vanadium will increase the
number of austenitic grain boundary and at the same time
reduce the grain size. Vanadium existed in the crystals
will cause changes of stress field; it can serve as a new
nucleating center for austenite. If Vanadium existed in
the grain boundary, it had a strong interaction with other
atoms around it. This was an effective way to prevent the
migration of sub-grain boundary and grain boundary and
inhibit growing of grains. V(C, N) could be a
non-spontaneous nucleating center for intragranular fer-
rite and play a very important role on grain refinement.
In summary, the ultra-fine ferrite grains in
V-microalloyed steels were mainly formed due to com-
bined effect of fragment of deformed austenite, the pin-
ning of V(C, N) nanophase on substructure, intragranular
nucleation and secondary nucleation(show in Fig.7).
Moreover, in order to investigate the appropriate particle
size of V(C, N) that can provide nucleation center for
intra-granular ferrite, a model of α nucleated on V(C,
N) interface was established(shows in Fig.8).
The free energy △G can be obtained by formula (3):
(3)
where, ΔGV is the transformation kinetics of unit volume,
r the radius ofα.
Fig.9 shows the relations between △G and r cal-
culated by formula(3). It can be inferred from Fig.9 that
the smallest nucleation energy △G was on the interface
of V(C, N). So the nucleation position for intra-granular
ferrite should be V(C, N) nanophase.
Differentiate on r in formula (3), then can obtain the
critical nucleation energy △Gcrit and criticalradius rcrit ofα.
3 2
4 ( ) / 3 4 ( )VG r G f r fγαθ σ θΔ = π Δ ⋅ + π ⋅
( )=(1 cos )(2+cos )/4f θ θ θ−
cosX Xγ α γασ σ σ θ− = ⋅
Fig.6 Ferrite grain size of test steel A, B and C holding for
different times after 70% deformation at 750 ℃
Fig.7 Formation of ultra-fine ferrite due to combined effect of fragment of deformed austenite, pinning of nanophase on substructure,
intragranular nucleation and secondary nucleation
6. Journal of Wuhan University of Technology-Mater. Sci. Ed. Apr.2010 233
(4)
(5)
The critical diameter of V(C, N) is:
(6)
By the above analysis, V(C, N) particle must have an
appropriate size to become nucleation center for in-
tra-granular ferrite. The size of V(C, N) particle changes
along with the change of △GV. Fig.10 shows the relationship
between the size of V(C, N) precipitates, the volume ratio of
ultra-fine ferrite and the grain size of ultra-fine ferrite in test
steel B and C in Table 1. For greatest display the grain re-
finement function of microalloyed contents, the size of V(C,
N) shouldbe controlledunder 100 nm. It canbe inferredfrom
Fig.10 that 20 nm-50 nm were the best size range. The grain
size of V(C, N) were less than 30 nm in the microalloyed
steels that with volume ratio of ultra-fine ferrite grater than
80% and grain size less than 4 μm.
4 Conclusions
a) In the experiment condition of present work, MnS,
in the traditional sense was a kind of harmful inclusions
in steels, could be transformed into beneficial inclusions.
It provided nucleating center for V(C, N) and intra-
granular ferrite, so that refined grains remarkably.
b) The experimental results strongly indicate that the
grain refining mechanism of MnS and MnS+V(C, N)
complex precipitates were its intercrystalline and secon-
dary nucleation can increase nucleating center for intra-
granular ferrite. Moreover, substructure such as grain
boundary, sub-boundary, distortion band, dislocation and
dislocation cell wall in austenite increased as the defor-
mation energy leaded in by heavy deformation at low
temperature. As a result, V(C, N) nanophase precipitated
at these substructures, which pinned and stabilized sub-
structure, thus refined ferrite grains furthermore.
c) The nucleating energy of IGF was the smallest on
V(C, N) phase interface. 20 nm-50 nm were the best
grain size range of V(C, N) as it provide nucleating center
for intragranular ferrite.
d) It was shown that there exist a linear relationship
between the size of precipitates and the grain size of fer-
rite. The grain size of V(C, N) were less than 30 nm in the
microalloyed steels that with volume ratio of ultra-fine
ferrite more than 80% and grain size less than 4 μm.
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3 2
crit 4 ( ) (1 cos )(2 cos ) / 3( )VG Gγασ θ θΔ = π − + Δ
crit 2 / Vr Gγασ= − Δ
crit crit2 4 / Vd r Gγασ= ⋅ = − Δ
Fig.8 Model ofαucleated on V(C, N) interface
Fig.9 Relations between ΔG and radius ofα
Fig.10 The relationship between the size of precipitates, the vol-
ume ratio of ultra-fine ferrite and the grain size of ultra-fine
ferrite in test steel B and C in Table 1