中文摘要：

在DIL805A/T热模拟机上对60Si2CrVAT弹簧钢进行了等温单向热拉伸实验,研究了该弹簧钢在温度900-1050℃、应变速率0.001-1s^-1条件下的高温变形及动态再结晶行为。使用包含变形激活能Q和温度T的双曲正弦形式修正的Arrhenius关系来描述60Si2CrVAT弹簧钢高温拉伸变形时的最大变形抗力方程;在此基础上,引入参数α（ε）、n（ε）、Q（ε）和A（ε）得到包含σ、ε、T、ε的本构方程。结果表明,由本构方程计算得到的应力值和实验值有较好相关性（R^2=0.98985）,平均相对误差绝对值为3.6646%;最后采用加工硬化率法通过对θ-σ和lnθ-ε曲线进行三次多项式拟求解拐点的方法,得到了不同变形条件下发生动态再结晶的临界应力和临界应变值,建立了临界应力、临界应变和Z参数的关系,得到了动态再结晶的临界应力和临界应变方程。

英文摘要：

The high temperature tensile behavior of 60Si2CrVAT spring steel at temperature range from 900 to 1050 ℃ and strain rates from 0. 001 to 1 s^-1 was investigated by single-pass tension tests on DIL805A/T thermo-mechanical simulator. The modified Arrhenius model, which is a hyperbolic sine function including the material parameter function of a（ε） ,n（ε） ,Q（ε） and A（ε）, was used to describe the hot tension constitutive equations of 60Si2CrVAT spring steel. The flow stress values predicted by the proposed model showed a good agreement with experimental results by the evidence of reproducing true stress-strain curves accurately, with high value of correlation coefficient （R^2 =0. 98985）and low value of average absolute relative error（3. 6646%）. The critical stress and critical strain for dynamic recrystallization（DRX） under different deformation conditions were accurately calculated based on the method of work hardening rate and the inflection points, which is the critical stress and strain, were determined by fitting a third order polynomial to the θ-σ and lnθ-ε curves, respectively, and the mathematical models of critical stress and critical strain versus Z parameter were deduced.