超细晶钢在不同温度下塑性变形机制的研究

Mechanisms of Plastic Deformation of Ultrafine Grained Steel at Different Temperatures

将晶粒尺寸分别为 2、7、80 μm的微合金钢在 2 95～ 973K温度范围内进行单轴拉伸试验 ,通过对比分析 3种不同晶粒尺寸微合金钢的工程应力—应变曲线及微观组织 ,讨论了超细晶粒钢在不同温度下的塑性变形机制。在 2 95～ 4 73K范围内 ,3种不同晶粒尺寸微合金钢的塑性变形机制以位错运动为主 ;在 5 73K,晶界滑动开始在超细晶粒钢中出现 ,在 973K,成为塑性变形的主导机制 ;粗晶粒钢在 5 73～

Uniaxial tensile tests are carried out for microalloyed steels with mean grain sizes of 2,7 and 80 μm respectively at 295~973 K.By comparing the tensile stress-strain curves and microstructures of three steels, the deformation mechanisms of three steels at different temperatures, with emphasis on ultrafine grained steel, are discussed. In 295～473 K,the main deformation mechanisms of the three steels are dislocation movement. At 573 K,grain boundary sliding and grain rotation begin to occur, and become main deformation mechanisms at 973 K. For coarse-grained steels, dislocation movement is the prodominent deformation mechanism at 573～973 K.