应变速率和变形温度对T122耐热钢流变应力和临界动态再结晶行为的影响

INFLUENCES OF STRAIN RATE AND DEFORMATION TEMPERATURE ON FLOW STRESS AND CRITICAL DYNAMIC R ECRYSTALLIZATION OF HEAT RESISTANT STEEL T122

利用Gleeble－3500热模拟试验机研究了T122耐热钢在900-1200℃,应变速率为10-2—lO1s-1条件下的热压缩变形行为．采用应变硬化速率—应力(θ－σ)曲线图较精确地获得了饱和流变应力和峰值应力;用回归法确定了双曲线本构方程中的变形激活能及材料常数,确定了T122钢在饱和应力和峰值应力条件下的变形激活能分别为570和548 kJ／mol;采用力学方法直接从流变曲线确定了T122钢发生动态再结晶的临界应变量,并回归出临界应变量与Zener—Hollomon参数的关系式．

The hot deformation behavior of the heat resistant steel T122 was investigated with a compression test on Gleeble 3500 simulator at a temperature range of 900-1200 ℃ and strain rate range of 10^-2-10^1 s^-1. A method was developed to determine the activation energy and material parameters in the hyperbolic sine constitutive equation. The activation energies determined are 570 kJ/mol and 548 kJ/mol for steel T122 in saturation stress and peak stress, respectively. The values of critical strain for dynamic recrystallization （DRX） initiation was determined from the strain-stress curves, a equation related to the Zener-Hollomon parameter was obtained.