基于焊接热模拟的高锰TWIP钢热影响区组织与性能

Microstructure and mechanical properties of heat affected zone for high-Mn TWIP steel based on welding thermal simulation

针对锻态高锰孪生诱导塑性钢利用Gleeble3500型热模拟试验机,通过设置不同峰值温度(850,950,1050,1150,1250℃)对焊接接头热影响区的各个区间进行了焊接热模拟,采用电子背散射衍射系统、扫描电子显微镜和X射线衍射仪等手段分析了锻态母材经过焊接热作用后组织和性能的变化.结果表明,热作用前后孪生诱导塑性钢组织均为等轴晶粒的全奥氏体组织,晶粒尺寸随峰值温度的上升先减小后增加,但都低于母材;热影响区的拉伸性能均优于母材,主要原因是发生了细晶强化;冲击韧性随峰值温度的变化与晶粒尺寸变化趋势一致,说明晶粒尺寸对采用的孪生诱导塑性钢冲击韧性有关,晶粒尺寸越细,冲击韧性越差.冲击断口的韧窝底部发现有AlN颗粒.

In this paper,the welding thermal simulation was performed on the forged high-Mn twinning induced plasticity steel by setting different peak temperatures(850,950,1050,1150 and 1250℃)in each interval of the heat affected zone of the welded joint using the Gleeble 3500 thermal simulation tester.Electron backscatter diffraction system,scanning electron microscopy and X-ray diffraction were used to analyze the changes in the microstructure and properties of the forged base material after the thermal action of welding.The results show that the microstructure of twinning induced plasticity(TWIP)steel before and after the thermal action is all-austenitic with equiaxed grains,and the grain size firstly decreases and then increases with the rise of the peak temperature,but is still lower than that of the base material.The tensile properties in the heat-affected zone are better than those of the base material,mainly due to the occurrence of fine grain strengthening.The impact toughness of the twin-induced plasticity steel is related with grain size in this study,and the finer the grain size,the worse the impact toughness.AlN particles were。