Dynamic recrystallization kinetics of 42CrMo steel during compression at different temperatures and strain rates

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• 作者：Guo-Zheng Quan ; ^a ; ^{quangz_2006@yahoo.com.cn} ; Gui-Sheng Li^a ; Tao Chen^a ; Yi-Xin Wang^a ; Yan-Wei Zhang^a ; Jie Zhou^a
• 关键词：Dynamic recrystallization ; Critical strain ; Flow stress ; High-strength steel
• 刊名：Materials Science and Engineering: A
• 出版年：2011
• 出版时间：25 May 2011
• 年：2011
• 卷：528
• 期：13-14
• 页码：4643-4651
• 全文大小：1879 K

文摘

In order to improve the understanding of the coupling effect in dynamic recrystallization (DRX) behavior and flow behavior for extruded 42CrMo high-strength steel, a series of isothermal upsetting experiments with height reduction of 60 % were performed at the temperatures of 1123 K, 1198 K, 1273 K and 1348 K, and the strain rates of 0.01 s⁻¹, 0.1 s⁻¹, 1 s⁻¹ and 10 s⁻¹ on a Gleeble1500 thermo-mechanical simulator. The initiation and evolution of DRX were investigated by using the process variables derived form flow curves. By the regression analysis for conventional hyperbolic sine equation, the activation energy of DRX was determined as Q = 599.7321 kJ mol⁻¹, and a dimensionless parameter controlling the stored energy were determined as . Based on the conventional strain hardening rate curves (dσ/d versus σ), the characteristic parameters including the critical strain for DRX initiation (_c), the strain for peak stress (_p), and the strain for maximum softening rate (*) were identified. Based on the regression analysis results for a modified Avrami type equation X_DRX=1−exp{−[(ε−ε_c)/ε^*]^m} in which _c, * and m were described as ε_c=0.16707(Z/A)^0.06704, ε^*=0.61822(Z/A)^0.08207 and m = 3.85582 respectively, the evolutions of DRX volume were described as following: for a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing deformation temperature, in contrast, for a fixed temperature, it increases with increasing strain rate. Finally, the theoretical predictions were validated by the microstructure graphs.