回火对激光焊中锰钢焊接接头组织和力学性能的影响

Effect of Tempering on Microstructure and Mechanical Properties of Laser Welded Medium-manganese Steel Joints

采用光纤激光器对冷轧中锰钢进行对接焊,并对焊接接头进行250和550℃回火处理,研究了回火对焊接接头组织和力学性能的影响。结果表明:焊态试样焊缝组织为全马氏体,回火态试样焊缝组织为回火马氏体。焊态和250℃回火试样均无塑性,为完全界面断裂;550℃回火试样塑性显著提升,断后伸长率达11.7%,约为母材的75.3%,断裂界面存在韧窝。焊后回火可显著提高焊缝的塑性,从而提高焊接接头的力学性能。

Cold-rolled medium-manganese steels were butt-welded by using a fiber laser,and the weld joints were tempered at 250 and 550℃.The effect of tempering on the microstructure and mechanical properties of the weld joints was studied.The results showed that the weld microstructure of as-welded sample was martensite,and that of tempered sample was tempered martensite.The as-welded sample and the sample tempered at 250℃all had no plasticity and showed complete interfacial fracture.However,the plasticity of the sample tempered at 550℃was significantly improved,and it’s elongation was up to 11.7%which was about 75.3%of the base metal,and there were dimples at the fracture interface.The post-weld tempering could significantly improve the plasticity of the weld,thus improving the mechanical properties of the weld joint.