采用Gleeble-3800热力模拟试验机在温度为1123~1423 K、应变速率为0.001~10 s^-1的条件下对2101双相不锈钢进行了热压缩实验,以研究热变形参数对其热加工行为的影响规律。结果表明,相同应变速率下,随温度升高,流变曲线由动态再结晶向动态回复转变。变形速率由0.001 s^-1增至0.01和0.1 s^-1提高了动态再结晶温度范围,而1和10 s^-1的较高应变速率不利于动态再结晶。在应变速率为0.001~0.1s^-1、变形温度为1253~1323 K时,峰值应力所对应的应变越小,奥氏体动态再结晶越容易发生,有利于等轴状再结晶组织形成。低应变速率下,变形温度升高使奥氏体再结晶晶粒长大,且Zener-Hollomon参数较大时,动态再结晶效果变差与Mn稳定奥氏体能力较Ni弱有关。基于热变形方程计算得到该不锈钢热变形激活能Q=464.49 kJ/mol,略高于2205双相不锈钢,并建立了峰值流变应力本构方程。结合不同变形条件下的应变曲线和显微组织,根据热加工图确定了最佳热加工区域为应变速率在0.001~0.1 s^-1、变形温度为1220~1350 K,该区域功率耗散系数处于0.40~0.47的较高值,发生了明显奥氏体动态再结晶。

The thermal deformation difference of two phases for duplex stainless steel (DSS) makes hot working difficult, 2101 DSS substitute Mn, N for Ni to stabilize austenite phase, which will significantly affect hot deformation behavior. Hot compression tests in the temperature ranging from 1123 to 1423 K and strain rate ranging from 0.001 to 10 s^-1 were carried out on a Gleeble-3800 thermal simulator for 2101 DSS. At the same strain rate, the flow curve characteristics of 2101 DSS changed from dynamic recrystallization (DRX) to dynamic recovery with increasing deformation temperature. Increasing deformation stain rate from 0.001 s^-1 to 0.01 and 0.1 s^-1 increased DRX temperature range, but higher strain rate of 1 and 10 s^-1 is not beneficial to DRX occurrence. In the deformation temperature region of 1253~1323 K and low strain rate of 0.001~0.1 s^-1, the smaller strain value corresponding to the peak stress, the austenite DRX is more likely to occur, which is beneficial to the equiaxed recrystallized grains formation. At low strain rate, the recrystallization grain grows up with the increase of deformation temperature, the worse effect of austenite DRX is related to weakened austenite stabilized ability of Mn substitution for Ni at high Zener-Hollomon parameter values. Based on the thermal deformation equation, the apparent activation energy Q was calculated as 464.49 kJ/mol, which is slightly higher than that of 2205 DSS, and the constitutive equation of the peak flow stress was established. By combining with flow curve and microstructure analysis, the processing map exhibits the optimum processing conditions are in deformation temperature ranging from 1220 to 1350 K and strain rate ranging from 0.001 to 0.1 s^-1 with high power dissipation coefficient of 0.40~0.47, under which the austenite DRX obviously occurred.