不锈钢热压变形组织不均匀性的有限元分析与试验

 采用有限元方法对AISI 304钢经1100℃，0.1,1,10s-1的热压变形过程进行了数值模拟，分析了变形试样上等效应变的分布情况，确定了实际变形条件与试验设定条件之间的关系及合理的组织观察位置，研究了不均匀变形对奥氏体显微组织变化的影响。结果表明：不锈钢热压试样变形与组织不均匀性十分明显，心部的等效应变比实际设定值大40％左右，而端面值小于设定值的1/6，且应变速率对等效应变的分布情况影响不大；1100℃，1s-1，设定真应变为1（工程应变为63.2%）的试验条件下，变形试样心部组织发生完全动态再结晶，变形轴线端面位置组织与未变形组织形貌相似，且试样截面上硬度分布不均匀，沿变形轴线方向，硬度从端面到心部逐渐增大，端面硬度最小值为238HV，心部硬度最大值为251HV。

FEM Analysis and Experiment of Hot Compression Nonuniformity for Stainless Steel

The hot compressing processes of AISI 304 stainless steel in 1100℃ were simulated with finite element method (FEM) at the strain rate 0.1, 1 and 10s-1. The distribution of efficient strain was analyzed in the deformed samples. The relationship between practical deforming condition and testing stated condition was determined, which was confirmed by the microstructure evolution of experimental steel. The effect of the non-uniform deformation on austenitic microstructure evolution was studied. The results indicate as follows: the deformation and structure uniformity is obvious at hot pressing samples of the experimental stainless steel. The equivalent strain in the center is about 40% larger than the stated value, the value in the surface is less than 1/6 of the stated value, and the effect of strain rate on the distribution of equivalent strain is little. Dynamic recrystallization occurs in the center of the deformed sample (1100℃, 1s-1, 63.2%), the microstructure in the surface of deformed samples is similar to the non-deformation morphology. The hardness distribution of the deformed sample is uneven. Along the deforming axis direction, the hardness gradually increases from the surface to the center, the minimum hardness in the surface is 238HV, and the maximum hardness in the center is 251HV.