Study on Deformation-Induced Pearlite Transformation in Vanadium Microalloyed Eutectoid Steel

2019 ◽  
Vol 1156 ◽  
pp. 17-24
Author(s):  
Cai Zhen ◽  
Xin Ping Mao ◽  
Si Qian Bao ◽  
Zhao Gang
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Microalloyed Steel ◽  
Hot Compression ◽  
Lower Strain Rate ◽  
Compression Tests ◽  
Eutectoid Steel ◽  
Lower Strain ◽  
Vanadium Carbides

In this paper, the hot compression tests were performed to study on deformation-induced pearlite transformation in vanadium microalloyed eutectoid steel. The results showed that volume fraction of deformation -induced pearlite were higher and the pearlite were spheroidized better under lower strain rate and higher strain in vanadium microalloyed steel. Ferrite grains and granular cementites were further refined through vanadium microalloying combined with deformation-induced pearlite transformation .Vanadium dissolved in γmatrix could retard deformation-induced pearlite transformation under low strain, vanadium carbides precipitated due to strain-induced precipitation eliminate the retardation when the strain was increased to a certain extent. Under heavy deformation, ferrite grains and granular cementites in vanadium microalloyed steel were finer compared with vanadium free steel.

scholarly journals Hot Workability of 300M Steel Investigated by In Situ and Ex Situ Compression Tests

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 880 ◽  
Author(s):  
Rongchuang Chen ◽  
Haifeng Xiao ◽  
Min Wang ◽  
Jianjun Li
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Working ◽  
Ex Situ ◽  
Lower Strain Rate ◽  
Hot Workability ◽  
Compression Tests ◽  
300M Steel ◽  
Lower Strain

In this work, hot compression experiments of 300M steel were performed at 900–1150 °C and 0.01–10 s−1. The relation of flow stress and microstructure evolution was analyzed. The intriguing finding was that at a lower strain rate (0.01 s−1), the flow stress curves were single-peaked, while at a higher strain rate (10 s−1), no peak occurred. Metallographic observation results revealed the phenomenon was because dynamic recrystallization was more complete at a lower strain rate. In situ compression tests were carried out to compare with the results by ex situ compression tests. Hot working maps representing the influences of strains, strain rates, and temperatures were established. It was found that the power dissipation coefficient was not only related to the recrystallized grain size but was also related to the volume fraction of recrystallized grains. The optimal hot working parameters were suggested. This work provides comprehensive understanding of the hot workability of 300M steel in thermal compression.

Optimization of the Chemical Composition and Homogenization Treatment of AA7020 Aluminum Alloy

2010 ◽  
Vol 89-91 ◽  
pp. 177-183 ◽  
Author(s):  
Ali Reza Eivani ◽  
H. Ahmed ◽  
Jie Zhou ◽  
Jurek Duczczyk
Keyword(s):  
Aluminum Alloy ◽  
Chemical Composition ◽  
Strain Rate ◽  
Hot Deformation ◽  
Volume Fraction ◽  
Hot Compression ◽  
Compression Tests ◽  
Homogenization Treatment ◽  
Aa7020 Aluminum Alloy

Four variants of AA7020 aluminum alloy having different Zr and Cr contents were investigated aiming at reaching high recrystallization resistance during and after hot deformation. Isothermal homogenization treatments were performed at temperatures of 390-550 °C for 2 to 48 hours. The uni-axial hot compression tests were conducted at 450 °C and strain rate of 10 s-1 at a strain of 0.6. Thereafter, the samples were annealed at 550 °C for 10 min. It was found that the samples with the highest Zr and Cr contents showed the lowest volume fraction of recrystallized grains which was attributed to the highest volume fraction of Zr- and Cr-containing dispersoids formed during homogenization. The optimum homogenization treatment to achieve highest recrystallization resistance for these samples was 470 °C for 24 hours.

Hot Deformation Behaviors of SiCp/Al Composites

2014 ◽  
Vol 1058 ◽  
pp. 165-169 ◽  
Author(s):  
Shi Ming Hao ◽  
Jing Pei Xie
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
True Strain ◽  
Constant Strain Rate ◽  
Hot Compression ◽  
Compression Tests ◽  
Sensitive Material ◽  
2024 Aluminum Alloy ◽  
Deformation Behaviors

The hot deformation behaviors of 30%SiCp/2024 aluminum alloy composites was studied by hot compression tests using Gleeble-1500 thermomechanical simulator at temperatures ranging from 350-500°C under strain rates of 0.01-10 s-1. The true stress-true strain curves were obtained in the tests. Constitutive equation and processing map were established. The results show that the flow stress decreases with the increase of deformation temperature at a constant strain rate, and increases with the increase of strain rate at constant temperature, indicating that composite is a positive strain rate sensitive material. The flow stress behavior of composite during hot compression deformation can be represented by a Zener-Hollomon parameter in the hyperbolic sine form. Its activation energy for hot deformation Q is 183.251 kJ/mol. The optimum hot working conditions for this material are suggested.

Hot Deformation Behavior and Microstructure of U720Li Alloy

2013 ◽  
Vol 709 ◽  
pp. 143-147 ◽  
Author(s):  
Tao Wang ◽  
Zhao Li ◽  
Shu Hong Fu ◽  
Yong Zhang ◽  
Yu Xin Zhao ◽  
...  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Primary Phase ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Fine Grain ◽  
Lower Strain

The hot deformation behavior of U720Li was investigated by isothermal compression tests at temperature ranging from 1060-1180°C and strain rate from 0.001s-1 to 20s-1. The flow stress-strain curves and microstructures were investigated and a constitutive equation was established. It is found that flow stress is sensitive to stain rate and deformation temperature greatly. The higher stain rate resultes in a larger fluctuation in flow stress. The hot deformation activation energy is determined to be 552.8kJ/mol. Grain size increases with increasing temperature and decreases firstly and then increases with increasing strain rate. U720Li alloy should be deformed below the solve temperature of γ primary phase with lower strain rate in order to obtain the even and fine grain size.

High Temperature Deformation Mechanisms and Processing Map for Hot Working of Cast-Homogenized Mg-3Sn-2Ca Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 3616-3621 ◽  
Author(s):  
K.P. Rao ◽  
Y.V.R.K. Prasad ◽  
Norbert Hort ◽  
Karl Ulrich Kainer
Keyword(s):  
Strain Rate ◽  
Processing Map ◽  
Volume Fraction ◽  
Flow Instability ◽  
Back Stress ◽  
Hot Working ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Compression Tests

The hot working behavior of Mg-3Sn-2Ca alloy has been investigated in the temperature range 300–500 oC and strain rate range 0.0003–10 s-1, with a view to evaluate the mechanisms and optimum parameters of hot working. For this purpose, a processing map has been developed on the basis of the flow stress data obtained from compression tests. The stress-strain curves exhibited steady state behavior at strain rates lower than 0.01 s-1 and at temperatures higher than 350 oC and flow softening occurred at higher strain rates. The processing map exhibited two dynamic recrystallization domains in the temperature and strain rate ranges: (1) 300–420 oC and 0.0003–0.003 s-1, and (2) 420–500 oC and 0.003–1.0 s-1, the latter one being useful for commercial hot working. Kinetic analysis yielded apparent activation energy values of 161 and 175 kJ/mole in domains (1) and (2) respectively. These values are higher than that for self-diffusion in magnesium suggesting that the large volume fraction of intermetallic particles CaMgSn present in the matrix generates considerable back stress. The processing map reveals a wide regime of flow instability which gets reduced with increase in temperature or decrease in strain rate.

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.

Effect of Hot Deformation Parameters on Flow Behavior and Microstructure of Ti-6Al-4V-0.2O Alloy

2017 ◽  
Vol 898 ◽  
pp. 137-143
Author(s):  
Lin Xiang ◽  
Bin Tang ◽  
Hong Chao Kou ◽  
Jie Shao ◽  
Jin Shan Li
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Dynamic Recovery ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Strain Rates ◽  
Compression Tests ◽  
Height Reduction ◽  
Deformation Parameters

Isothermal compression tests were conducted to investigate the effect of hot deformation parameters on flow behavior and microstructure of Ti-6Al-4V-0.2O alloy. The experimental results show that the strain rate and height reduction have little effect on the volume fraction of primary α at a deformation temperature of 860 ̊C. At a deformation temperature of 940 ̊C, the volume fraction of primary α at a high strain rate (10s-1) is about 10% less than that at low strain rates (0.01s-1~1s-1). It may be one of the reasons for the significantly discontinuous yielding phenomenon. Another reason is that the dislocation density decreased suddenly due to the dynamic recovery. With the increasing strain rate and the decreasing deformation temperature, the volume fraction of irregular secondary α increases and lamellar secondary α decreases. And with height reduction increasing, the irregular secondary α increases firstly and then tends to be steady because of dynamic recovery and recrystallization.

Dynamic Recrystallization Behavior of Mg-Gd-Y-Zr Alloy during Hot Compression

2016 ◽  
Vol 849 ◽  
pp. 181-185 ◽  
Author(s):  
Shi Lun Yu ◽  
Yong Hao Gao ◽  
Chu Ming Liu ◽  
Hong Chao Xiao
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Volume Fraction ◽  
Peak Stress ◽  
Critical Conditions ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Dynamic Recrystallization Behavior ◽  
Increasing Temperature ◽  
The Cost

Dynamic recrystallization behavior of Mg-8.0Gd-3.0Y-0.5Zr (wt.%) alloy and the critical conditions corresponding to the onset of dynamic recrystallization were investigated using uniaxial compression tests conducted at temperatures ranging from 350 °C to 500 °C and strain rates ranging from 0.001 s-1 to 1 s-1. Results show that increasing temperature and/or decreasing strain rate can enhance the process of dynamic recrystallization of Mg-8.0Gd-3.0Y-0.5Zr alloy and lower the peak stress and corresponding strain. However, decreasing temperature and/or increasing strain rate can promote the occurrence of twin dynamic recrystallization (TDRX) within the original grains at the cost of reducing the total volume fraction of dynamically recrystallized grains in the microstructure. Besides, the critical stress and strain corresponding to the onset of dynamic recrystallization of Mg-8.0Gd-3.0Y-0.5Zr at 400 °C and 0.1 s-1 are 173MPa and 0.13, respectively.

Influence of Mg Content, Grain Size and Strain Rate on Mechanical Properties and DSA Behavior of Al-Mg Alloys Processed by ECAP and Annealing

2014 ◽  
Vol 794-796 ◽  
pp. 870-875 ◽  
Author(s):  
Min Zha ◽  
Yan Jun Li ◽  
Ragnvald H. Mathiesen ◽  
Christine Baumgart ◽  
Hans J. Roven
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Strain Rate ◽  
Room Temperature ◽  
Uniform Elongation ◽  
Mg Alloys ◽  
Lower Strain Rate ◽  
Lower Strain ◽  
Mg Content ◽  
Al Mg Alloys

Ultrafine-grained (UFG) binary Al-xMg (x=1, 5 and 7 wt %) alloys were processed by equal channel angular pressing (ECAP) at room temperature via route Bccombined with inter-pass annealing. The effects of Mg content, grain size and strain rate on mechanical properties and dynamic strain aging (DSA) behaviour of the Al-Mg alloys upon tensile testing at room temperature were studied. An increase in Mg content from 5 to 7 wt % leads to a pronounced increase in strength and uniform elongation in both the as-homogenized and as-ECAP Al-Mg alloys. Thereby, the Al-7Mg alloy, either prior to or after ECAP processing, possess significantly higher strength and comparable or even higher uniform elongation than the more dilute Al-Mg alloys. However, the as-ECAP Al-Mg alloys exhibit significantly higher strength but little work hardening and hence rather limited uniform elongation. In general, decreasing grain size leads to significant increase in strength while dramatic decrease in ductility. Moreover, DSA serration amplitudes increase with reducing grain size in the micrometer range. However, the UFG Al-Mg alloys exhibit much less DSA effect than the micrometer scaled grain size counterparts, i.e. probably due to the high dislocation densities and special grain boundary features in the UFG materials. Also, the Al-Mg alloys, especially those with a UFG structure, exhibit higher strength and ductility at lower strain rate than at higher strain rate, due mainly to enhanced DSA effect and hence work hardening at a lower strain rate.

scholarly journals Influence of Vanadium Microalloying on Deformation-Induced Pearlite Transformation of Eutectoid Steel

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 268 ◽  
Author(s):  
Zhen Cai ◽  
Xinping Mao ◽  
Siqian Bao ◽  
Gang Zhao ◽  
Yaowen Xu
Keyword(s):  
Microalloyed Steel ◽  
Small Strain ◽  
Vanadium Content ◽  
Transformation Kinetics ◽  
Eutectoid Steel ◽  
Vanadium Nitrides ◽  
Austenite Grain ◽  
Thermomechanical Simulation ◽  
Vanadium Carbides ◽  
Kinetics Of

In order to investigate the influence of vanadium microalloying on deformation-induced pearlite transformation (DIPT) of eutectoid steel, thermomechanical simulation tests were carried out in this study. The following four compositions of vanadium microalloying were applied in the tests: vanadium free in Steel A, vanadium content of 0.1 mass% in Steel B, vanadium content of 0.27 mass% in Steel C, and vanadium content of 0.1 mass% with the addition of 0.02 mass% N in Steel D. The dissolution of vanadium and precipitation of vanadium carbides, nitrides, or carbonitridesand the effect of vanadium microalloying on the fraction and morphology of deformation-induced pearlite for different magnitudes of strain were examined, and the mechanism of the effect was elucidated. The results revealed that DIPT could be significantly improved by vanadium microalloying with the addition of N but decreased and postponed without the addition of N because vanadium nitrides or carbonitrides were precipitated in austenite under a small strain and facilitated the nucleation of pearlite both along the boundary of austenite grain (AG pearlite) and intragranular (IG pearlite). Moreover, transformation kinetics of DIPT was fitted and compared. The results further revealed that the rate of DIPT in vanadium-microalloyed steel with the addition of N was twice as fast as that in the vanadium-free steel. In order to ensure the complete spheroidization of lamellar cementites in vanadium-microalloyed steel, a comparison of the morphology of cementites revealed that a greater magnitude of strain was required.

Sign in / Sign up

Export Citation Format

Share Document