Softening Behavior of Ti6Al4V Alloy during Hot Deformation

2015 ◽  
Vol 828-829 ◽  
pp. 407-412 ◽  
Author(s):  
Paul Micheal Souza ◽  
Hossein Beladi ◽  
Bernard Rolfe ◽  
Rajkumar Singh ◽  
Peter D. Hodgson
Keyword(s):  
Strain Rate ◽  
Microstructural Evolution ◽  
Volume Fraction ◽  
Softening Behavior ◽  
Strain And Strain Rate ◽  
Measured Activation Energy ◽  
Average Grain Size ◽  
Measured Activation ◽  
Equiaxed Grains ◽  
Good Agreement

The effect of strain rate and strain on the hot compression behaviour of Ti6Al4V has been analysed to understand the microstructural evolution and restoration behaviour. Cylindrical samples with partially equiaxed grains were deformed in the α+β region at different thermo-mechanical conditions. EBSD has been used to study the microstructural behaviour and the restoration mechanisms. The microstructural evolution showed a complex restoration behaviour, where both fragmentation and nucleation of new grains have been observed. The volume fraction of the equiaxed grains increased with an increase in the strain, but oppositely decreased with the strain rate. At the same time the average grain size of the equiaxed grains decreased with an increase in both the strain and strain rate. The measured activation energy for deformation revealed a good agreement with reported values in the literature.

Study on Dynamic Recrystallization Behavior in Deformed Austenite of 52100 Steel by Using JMAK-Model

2013 ◽  
Vol 275-277 ◽  
pp. 1833-1837
Author(s):  
Ke Lu Wang ◽  
Shi Qiang Lu ◽  
Xin Li ◽  
Xian Juan Dong
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Volume Fraction ◽  
True Strain ◽  
Strain And Strain Rate ◽  
Average Grain Size ◽  
Dynamic Recrystallization Behavior ◽  
Simulation And Experiment ◽  
Good Agreement

A Johnson-Mehl-Avrami-Kolmogorov (JMAK)-model was established for dynamic recrystallization in hot deformation process of 52100 steel. The effects of hot deformation temperature, true strain and strain rate on the microstructural evolution of the steel were physically studied by using Gleeble-1500 thermo-mechanical simulator and the experimental results were used for validation of the JMAK-model. Through simulation and experiment, it is found that the predicted results of DRX volume fraction, DRX grain size and average grain size are in good agreement with the experimental ones.

Hot Deformation Behavior and Microstructural Evolution of Mg-Nd-Zn-Zr Magnesium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 320-326 ◽  
Author(s):  
Wen Xiang Wu ◽  
Li Jin ◽  
Jie Dong ◽  
Zhen Yan Zhang ◽  
Wen Jiang Ding
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Hot Deformation ◽  
Fine Particles ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Average Size

The hot deformation behaviors and microstructural evolution of Mg-3.0Nd-0.2Zn-0.4Zr (wt. %, NZ30K) alloy were investigated by means of the isothermal hot compression tests at temperatures of 350-500 °C with strain rates of 0.001, 0.01, 0.1 and 1s-1. The results showed that the flow stress increased to a peak and then decreased which showed a dynamic flow softening. The flow stress behavior was described by the hyperbolic sine constitutive equation with an average activation energy of 193.8 kJ/mol. The average size of dynamically recrystallized grains of hot deformed NZ30K alloy was reduced by increasing the strain rate and/or decreasing the deformation temperature. A large amount of fine particles precipitated in the grains interior and at the grain boundaries when heated to the compression temperatures and soaked for 5min below 450 °C. However, the volume fraction of particles decreased significantly when soaked for 5 min at 500 °C, and the coarse particles precipitated mainly at the grain boundaries. Hot deformation at the temperature of 500 °C around and at the strain rate range of 0.1s-1 was desirable for NZ30K alloy.

scholarly journals Hot Deformation Behavior and Microstructural Evolution of Twin-Roll-Casting Mg Alloy during High-Temperature Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Qingshan Yang ◽  
Jiahong Dai ◽  
Sensen Chai ◽  
Daliang Yu ◽  
Bin Jiang ◽  
...  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Microstructural Evolution ◽  
Deformation Behavior ◽  
Volume Fraction ◽  
Mg Alloy ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Average Grain Size ◽  
Twin Roll

The deformation behavior and microstructural evolution of twin-roll-casting AZ31 Mg alloy sheets were investigated via hot compression tests at 0°, 5°, and 10° from the normal direction. Compression strains of 5%, 15%, 25%, and 35% were employed at high temperatures of 450°C and 500°C. The flow stress as well as the difference in the flow stress associated with different sampling directions decreased when the temperature was increased. Furthermore, the volume fraction of dynamically recrystallized grains increased with increasing deformation, whereas the average grain size decreased. The DRX grain size and the volume fraction of dynamically recrystallized grains increased with increasing deformation temperature. During ultrahigh temperature compression, the effect of sampling direction on the compression microstructure is relatively small.

Dynamic recrystallization and microstructure evolution of AZ31 magnesium alloy produced by extrusion through rotating container

2016 ◽  
Vol 30 (01) ◽  
pp. 1550261 ◽  
Author(s):  
Feng Li ◽  
Nan Bian ◽  
Yongchao Xu ◽  
Xiang Zeng
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Theoretical Basis ◽  
Volume Fraction ◽  
Az31 Magnesium Alloy ◽  
Average Grain Size ◽  
Distribution Uniformity ◽  
Equiaxed Grains

In order to research the dynamic recrystallization (DRX) and grain refinement mechanisms in the process of extrusion through the rotating container, hot compression experiment of AZ31 magnesium alloy was carried out. Through the combination of experimental data and Yada empirical model, the DRX model of AZ31 magnesium alloy was established. Based on this DRX model, the numerical simulation of AZ31 magnesium alloy extrusion through the rotating container process was performed. The research results indicated, with the same process parameters of conventional extrusion, the shear stress increased significantly at the same position during the process of extrusion through the rotating container. This stress change promoted the occurrence of DRX and the increased recrystallization volume fraction. The average grain size obviously decreased. The equiaxed grains increased and the distribution uniformity was improved. These characteristics provided a theoretical basis for a better understanding of the enhanced comprehensive mechanical properties during the extrusion through the rotating container.

Superplastic Behavior of an Al-Cu-Mg-Mn-Ag Alloy

2016 ◽  
Vol 870 ◽  
pp. 185-190
Author(s):  
F.F. Musin ◽  
B.O. Bolshakov ◽  
E. Domracheva
Keyword(s):  
Strain Rate ◽  
Microstructural Evolution ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Sensitivity Coefficient ◽  
Strain Rates ◽  
Thermomechanical Process ◽  
Average Grain Size ◽  
Elongation To Failure ◽  
Superplastic Properties

The superplastic properties and microstructural evolution of a commercial Al-4.4%Cu-0.5%Mg-0.4%Mn-0.5%Ag-0.1%Ti alloy were examined under tension at temperatures ranging from 450 to 520°C and strain rates ranging from 6.9x10-5 to 6.9x10-2s-1. The refined microstructure with an average grain size of about 11m was produced in thin sheets by a commercially viable thermomechanical process. The highest elongation to failure of 540% was attained at a temperature of 500°C and an initial strain rate of 6.9x10-4 s-1 with the corresponding strain rate sensitivity coefficient of 0.55. The microstructural evolution during superplastic deformation of the aluminum alloy has been studied quantitatively. Processing at temperatures above 475°C and strain rate below 1.4x10-3s-1 resulted in fracturing almost without necking with cavitation playing a major role in the failure. In contrast, at low temperatures and/or high strain rates, fracture occurred in a ductile manner by localized necking. The relationship between superplastic ductility and microstructural evolution is analyzed.

Kinetics of Reactions Relevant to the Chemical Vapor Deposition of Indium Compounds

1997 ◽  
Vol 495 ◽  
Author(s):  
M. D. Allendorf ◽  
A. H. McDaniel
Keyword(s):  
Molecular Beam ◽  
Flow Reactor ◽  
Chemical Vapor ◽  
Sampling System ◽  
Measured Activation Energy ◽  
Measured Activation ◽  
System Data ◽  
Indium Compounds ◽  
Kinetics Of ◽  
Good Agreement

ABSTRACTThe kinetics of trimethylindium pyrolysis are investigated in a flow reactor equipped with a molecular-beam mass-spectrometric sampling system. Data are analyzed using a new computational approach that accounts for heat and mass transport in the reactor. The measured activation energy, 46.2 kcal mol−1, is in good agreement with previously reported values.

scholarly journals Characterization of the Microstructure Evolution of Ni-Based Superalloy at Liquidus Temperature by Electromagnetic Field

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 748
Author(s):  
Zhongtang Gao ◽  
Jinqiang Tan ◽  
Wei Guo ◽  
Chuanwei Zhang ◽  
Wu Zhang
Keyword(s):  
Electromagnetic Field ◽  
Volume Fraction ◽  
Treatment Time ◽  
Treatment Temperature ◽  
Isothermal Treatment ◽  
Uniform Temperature ◽  
Melt Treatment ◽  
Average Grain Size ◽  
Equiaxed Grains

The effect of isothermal treatment temperatures and isothermal treatment time on the microstructure was studied. The results showed that the globular and equiaxed grains with the average grain size of 60 μm and the shape factor of circle of 0.95 can be obtained when the melt of Ni-Cr-W superalloy was subjected to the heat treatment of 10 min at 1400 °C. The quenching results showed the volume fraction of the eutectic phase was the largest and the volume fraction of primary γ phase was the smallest after the isothermal treatment of 1400 °C. The optimal melt treatment temperature and time were 1400 °C and 10 min, respectively. Moreover, the effect of electromagnetic field on the solidification was also investigated. It was demonstrated that applying electromagnetic field was beneficial to the uniform temperature, solute field and the high density of the secondary nuclei, which contributed to grain refinement.

Microstructural Evolution of 7050 Aluminum Alloy Semisolid Billets Fabricated by RAP Process

2014 ◽  
Vol 217-218 ◽  
pp. 29-36 ◽  
Author(s):  
Ju Fu Jiang ◽  
Zhi Ming Du ◽  
Ying Wang ◽  
Shou Jing Luo
Keyword(s):  
Aluminum Alloy ◽  
Microstructural Evolution ◽  
Ostwald Ripening ◽  
Soaking Time ◽  
Isothermal Temperature ◽  
7050 Aluminum Alloy ◽  
Average Grain Size ◽  
Different Temperatures ◽  
Equiaxed Grains ◽  
Grain Coalescence

In the present study, 7050 supplied in extruded state was heated to different temperatures below solidus or the semisolid state and microstructural evolution and coarsening were investigated. The results showed that complete recrystallisation only occurs after soaking for 5 minutes at 545°C, which is characterised by formation of a lot of fine equiaxed grains. RAP is suitable for fabricating high-quality semisolid billet of 7050 aluminum alloy with an average grain size ranging from 47.4 um to 70.5 um and a roundness ranging from 1.3 to 1.7. Grain growth occurs as the samples were soaked at 610°C and 615°Cfor prolonged soaking time. When the isothermal temperatures were 610°C and 615°C, the coarsening rate constants were 359.5μm3s-1 and 470.5μm3s-1, respectively, indicating an increase of coarsening rate constant (K) with the increasing isothermal temperature. Coarsening tends to occur via Ostwald ripening and coalescence. Ostwald ripening plays an important role during the whole coarsening process, but the grain coalescence only contributes to coarsening after soaking for 12 minutes. 625°C is an optimal temperature to keep cylinder shape of the sample due to collapse of the sample above this temperature, leading to difficult clamping.

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