超低碳13Cr-5Ni-2Mo马氏体不锈钢热变形行为及本构关系

 利用Gleeble-3800热模拟试验机对超低碳13Cr-5Ni-2Mo马氏体不锈钢进行单道次高温压缩试验，研究其在900～1 200 ℃、0.1～50 s-1条件下的热变形行为，并讨论了不同变形条件下的微观组织演变规律；基于Sellars双曲正弦模型构建了超低碳13Cr-5Ni-2Mo 马氏体不锈钢的高温流变应力本构方程。研究结果表明，变形温度越高、应变速率越低，则流变应力越小，峰值应变也越小，微观组织由动态回复型向动态再结晶型转变，并且晶粒逐渐长大、粗化。在高温区变形，随着应变速率的升高，动态再结晶晶粒明显细化。所建立的本构方程具有较高的精确度，能反映超低碳13Cr-5Ni-2Mo 马氏体不锈钢的高温变形力学行为，可为热加工数值模拟研究提供参考。

Hot Deformation Behavior and Constitutive Relationship for Super-Low Carbon 13Cr-5Ni-2Mo Martensitic Stainless Steel

The hot deformation behavior of super-low carbon 13Cr-5Ni-2Mo martensitic stainless steel was investigated by high temperature compression tests on a Gleeble-3800 thermal-mechanical simulator in the range of deformation temperature from 900 to 1 200 ℃,strain rate from 0.1 to 50 s-1.Microstructural evolutions under different working conditions were also analyzed.The constitutive equation of flow stress was formulated with Sellars’ hyperbolic sine model.The results show that the flow stress and the critical strain to the peak stress decrease with the increase in temperature and the decrement of strain rate.Meanwhile,the dynamic recovery turns to the dynamic re-crystallization,and recrystallization grains grow and then coarse gradually.In the high temperature range,the re-crystallization grain size decreases obviously with the increase of strain rate.The high accuracy of the developed constitutive equation is identified,which reveals that it can effectively reflex the high temperature mechanical behavior of the tested steel and provides valuable consults for numerical simulation in hot working.