The Dynamic Recrystallization of Hot-Deformed Austenite in a Micro-Alloyed Steel

2012 ◽  
Vol 724 ◽  
pp. 287-290
Author(s):  
Yuan She ◽  
Zhao Hui Zhang ◽  
Jun Yang ◽  
Jian Tao Ju
Keyword(s):  
Dynamic Recrystallization ◽  
Peak Stress ◽  
Controlled Rolling ◽  
Alloyed Steel ◽  
Compression Tests ◽  
Austenite Grain Size ◽  
Alloyed Element ◽  
Deformation Equation ◽  
Dynamic Recrystallization Behavior ◽  
Micro Alloyed Steel

As the dynamic recrystallization (DRX) behavior of hot-deformed austenite is the basis of determining controlled rolling schedule for steel, in the present work, the dynamic recrystallization behavior of austenite of a 0.22%C-1.30%Mn-0.04%Nb micro-alloyed steel was investigated by means of high temperature compression tests on the Thermecmastor-Z simulator. By the analysis of true stress-strain curves at different deformation stages, the hot deformation equation of austenite was established for the steel. As a result, the energy to induce recrystallization of austenite for the steel is 419.1 kJmol-1, as it was influenced by the drag effect of micro-alloyed element Nb in solid solution. The ratio (σc/σp) of critical stress σc (where DRX occurs) to peak stress σp is 0.93 while the ratio (εc/εp) of critical strain εc to peak stress εp is 0.52 for the steel. The austenite grain size of dynamic recrystallization of the micro-alloyed steel is refined by decreasing the deformation temperature and improving the stain rate.

scholarly journals Study of Static Recrystallization Kinetics and the Evolution of Austenite Grain Size by Dynamic Recrystallization Refinement of an Eutectoid Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1289
Author(s):  
Cesar Facusseh ◽  
Armando Salinas ◽  
Alfredo Flores ◽  
Gerardo Altamirano
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Static Recrystallization ◽  
Controlled Rolling ◽  
Strain Rates ◽  
Peak Strain ◽  
Compression Tests ◽  
Eutectoid Steel ◽  
Austenite Grain Size ◽  
Austenite Grain

Interrupted and continuous hot compression tests were performed for eutectoid steel over the temperature range of 850 to 1050 °C and while using strain rates of 0.001, 0.01, 0.1, and 1 s−1. The interrupted tests were carried out to characterize the kinetics of static recrystallization(SRX) and determinate the interpass time conditions that are required for initiation and propagation of dynamic recrystallization (DRX), while considering that the material does not contain microalloying elements additions for the recrystallization delay. Continuous testing was used to investigate the evolution of the austenite grain size that results from DRX. The results indicate that carbon content accelerates the SRX rate. This effect was observed when the retardation of recrystallization due to a decrease in deformation temperature from 1050 to 850 °C was only about one order of magnitude. The expected decelerate effect on the SRX rate when the initial grain size increases from 86 to 387 µm was not significant for this material. Although the strain parameter has a strong influence on SRX rate, in contrast to a lesser degree of strain rate, both of the effects are nearly independent of the chemical composition. The calculated maximum interpass times that are compatible with DRCR (Dynamic Recrystallization Controlled Rolling), for relatively low strain rates, suggest that the onset and maintaining of the DRX is possible. However, while using the empirical equations that were developed in the present work to estimate the maximum times for high strain rates, such as those observed in the wire and rod mills, indicate that the DRX start is feasible, but maintaining this mechanism for 5% softening in each pass after peak strain is not possible.

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.

Kinetics of Dynamic Recrystallization of 18 Ni Maraging Steels

2016 ◽  
Vol 850 ◽  
pp. 13-20 ◽  
Author(s):  
Ni Li ◽  
Fei Zhao ◽  
Huan Zhang ◽  
Yong Hai Ren
Keyword(s):  
Dynamic Recrystallization ◽  
Peak Stress ◽  
Strain Rates ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Flow Curves ◽  
Maraging Steels ◽  
Dynamic Recrystallization Behavior ◽  
Characteristic Values ◽  
Kinetics Of

The dynamic recrystallization behavior of 18 Ni maraging steels was investigated by hot compression tests at temperatures ranging from 900 °C to 1100 °C and strain rates ranging from 0.001 to 1 s-1. Based on the flow curves from the tests, the effects of temperatures and strain rates on the dynamic recrystallization behavior were analyzed. The strain-hardening rates versus stress curves were used to determine to the critical strain, the peak stress (strain), the saturated stress and the steady stress. With the assistance of the process parameters, constitutive equations were obtained and the activation energy was determined to be 413544.96 J/mol. The dependence of the characteristic values on Zener-Hollomon was found. The dynamic recrystallization kinetics model of the tested steels was constructed and the validity was confirmed based on the experimental results.

Dynamic Recrystallization Behavior of High Carbon Chromium Bearing Steel

2014 ◽  
Vol 584-586 ◽  
pp. 1011-1016
Author(s):  
Xiao Lei Zhang ◽  
Hui Li ◽  
Shi Xin Xu ◽  
Zhi Chao Li ◽  
Zhen Li Mi
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Peak Stress ◽  
Bearing Steel ◽  
Peak Strain ◽  
Compression Tests ◽  
Gcr15 Bearing Steel ◽  
Dynamic Recrystallization Behavior ◽  
Gleeble 3500 ◽  
Relationship Of

The effect of process parameters on dynamic recrystallization of GCr15 bearing steel was investigated by a single-pass compression tests using Gleeble-3500 thermal simulator. The results indicate that the flow stress decreases with the increasing of temperature and the decreasing of strain rate. The dynamic recrystallization rate increases with the increasing of deformation temperature. By regression analysis, the mean activation energy and the stress exponent are determined to be 435.1KJ/mol-1and 5.0505 respectively. Meanwhile, the kinetic mathematical model of dynamic recrystallization and constitutive equation are established.The relationship of peak stress, peak strain and Z parameters is founded by using the data of flow stress curves.

scholarly journals Hot Deformation Characteristics and 3-D Processing Map of a High-Titanium Nb-Micro-alloyed Steel

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1501 ◽  
Author(s):  
Pingping Qian ◽  
Zhenghua Tang ◽  
Li Wang ◽  
Charles W. Siyasiya
Keyword(s):  
Hot Deformation ◽  
Peak Stress ◽  
Material Model ◽  
Alloyed Steel ◽  
Avrami Equation ◽  
Processing Maps ◽  
Compression Tests ◽  
Stress Strain ◽  
Distribution Maps ◽  
Micro Alloyed Steel

Hot deformation behavior of a high-titanium Nb-micro-alloyed steel was investigated by conducting hot compression tests at the temperature of 900–1100 °C and the strain rate of 0.005–10 s−1. Using a sinh type constitutive equation, the apparent activation energy of the examined steel was 373.16 kJ/mol and the stress exponent was 6.059. The relations between Zener–Hollomon parameters versus peak stress (strain) or steady-state stress (strain) were successfully established via the Avrami equation. The dynamic recrystallization kinetics model of the examined steel was constructed and the validity was confirmed based on the experimental results. The 3-D atomic distribution maps illustrated that strain can significantly affect the values of power dissipation efficiency and the area of instability domains. The 3-D processing maps based on a dynamic material model at the strains of 0.2, 0.4, 0.6 and 0.8 were established. Based on traditional and 3-D processing maps and microstructural evaluation, the optimum parameter of for a high-titanium Nb-micro-alloyed steel was determined to be 1000–1050 °C/0.1–1 s−1.

Constitutive Modeling of Dynamic Recrystallization Behavior of GH80A Superalloy

2013 ◽  
Vol 455 ◽  
pp. 71-76
Author(s):  
Hong Ke Wang ◽  
Li Wen Zhang ◽  
Sen Dong Gu ◽  
Qiu Hong Quan ◽  
Wen Fei Shen
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Experimental Results ◽  
Avrami Equation ◽  
Compression Tests ◽  
Stress Strain ◽  
Austenite Grain Size ◽  
Dynamic Recrystallization Behavior ◽  
Strain Model

The dynamic recrystallization (DRX) behavior of GH80A superalloy was investigated by isothermal compression tests on a Gleeble1500 thermomechanical simulator. True stress-strain curves and deformed specimens were obtained at the temperature range of 1273-1473K and the strain rate range of 0.01-5s-1. Experimental results show that the stress-strain curves at low strain rate display a typical DRX characteristic. By regression analysis of experimental results, Materials constant n, activation energy Q and Zener-Hollomon (Z) parameter were determined, and the critical strain model and austenite grain size model for dynamic recrystallization were established as a function of deformation temperature and strain rate. The dynamic recrystallization kinetic model for GH80A was established on the basis of the Avrami equation.

Dynamic Recrystallization Behavior of a New Lead-Free Machinable Brass during Hot Deformation

2015 ◽  
Vol 817 ◽  
pp. 444-448
Author(s):  
Chun Lei Gan ◽  
Kai Hong Zheng ◽  
Hai Yan Wang ◽  
Wen Jun Qi ◽  
Nan Zhou
Keyword(s):  
Dynamic Recrystallization ◽  
Peak Stress ◽  
Lead Free ◽  
Strain Rates ◽  
Compression Tests ◽  
Stress Strain ◽  
Rate Versus ◽  
Dynamic Recrystallization Behavior ◽  
Compression Data ◽  
Strain Hardening Rate

The dynamic recrystallization (DRX) behavior of the new lead-free machinable brass was investigated by compression tests on a Gleeble-1500 thermal mechanics simulator in the temperatures range of 823-973 K and strain rates ranging from 0.01 to 1 s-1. On the basis of the hot compression data, critical stress (strain) or peak stress (strain) were determined with the assistance of the strain hardening rate versus stress curves. The dynamic recrystallization kinetics model of the lead-free machinable brass was established to evaluate the DRX behavior. The results will be beneficial to optimizing hot working processes of this new lead-free machinable brass.

scholarly journals Influence of Rare Earth on Dynamic Recrystallization Behavior of As-Cast 30Mn Steel

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Honghong Yan ◽  
Yong Hu ◽  
Dawen Zhao
Keyword(s):  
Rare Earth ◽  
Dynamic Recrystallization ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Forming Process ◽  
Cast Slab ◽  
Forming Technology ◽  
Alloy Addition ◽  
Dynamic Recrystallization Behavior ◽  
Gleeble 3500

Based on casting-rolling compound forming process, the effect of rare earth on dynamic recrystallization (DRX) of as-cast 30Mn steel was investigated by the single-pass hot compression tests performed using a Gleeble-3500 thermomechanical simulator, and the deformation temperature range was 950°C–1150°C and strain rate range was 0.1–1 s−1. With the assistance of the process parameters, constitutive equations were used to obtain the activation energy and hot working equation. The dynamic recrystallization kinetics models of the tested steel were constructed. The results show that rare earth ferrosilicon alloy addition (0.2%, mass fraction) can delay the onset of DRX significantly and refine the hot deformation microstructures. All of the results indicate that the addition of rare earth into as-cast 30Mn steel is helpful to prepare excellent cast slab for the casting-rolling compound forming technology.

scholarly journals Hot Deformation Behavior and Processing Maps of Fe-30Mn-0.11C Steel

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1940 ◽  
Author(s):  
Jianmei Kang ◽  
Yuhui Wang ◽  
Zhimeng Wang ◽  
Yiming Zhao ◽  
Yan Peng ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
True Strain ◽  
Peak Stress ◽  
Strain Rates ◽  
Processing Maps ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
High Deformation

Hot deformation behavior of Fe-30Mn-0.11C steel was investigated. Hot compression tests were carried out at various temperatures ranging from 800 °C to 1200 °C and at different strain rates of 0.01 s−1 to 10 s−1. The constitutive equation based on peak stress was established. Hot processing maps at different strains and recrystallization diagrams were also established and analyzed. The results show that dynamic recrystallization easily occur at high deformation temperatures and low strain rates. Safe and unstable zones are determined at the true strain of 0.6 and 0.7, and the hot deformation process parameters of partial dynamic recrystallization of the tested steel are also obtained.

Effect of Deformation Conditions on Dynamic Recrystallization of As-Cast GH625 Alloy

2015 ◽  
Vol 816 ◽  
pp. 620-627
Author(s):  
Hao Yu Wang ◽  
Jian Xin Dong ◽  
Mai Cang Zhang ◽  
Lei Zheng ◽  
Zhi Hao Yao ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Process Design ◽  
Deformation Process ◽  
Strain Rates ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Volume Percent ◽  
Dynamic Recrystallization Behavior ◽  
Continuous Recrystallization

High temperature compression tests at a deformation temperature range of 1273K~1473K with various strain rates of 0.01s-1~0.1s-1 on as-cast GH625 alloy were carried out, aiming at the current research status that the deformation process of cogging and the recrystallization behavior of ingot are still in the study. The results indicated that the recrystallization nuclei of ingot formed not only along the original grain boundaries, but also in the interdendrite. Dynamic recrystallization volume percent increased with the increase of temperature and the decrease of strain rate. When the temperature was high and strain rate was low, the dynamic recrystallization behavior of as-cast GH625 alloy was dominated by discontinuous recrystallization. However, when the temperature was low and strain rate was high, continuous recrystallization also existed. These results can provide some reliable experimental support for the cogging process design.

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