异种钢激光焊接接头热成型后的组织与性能

Microstructure and Properties of Laser Welded Joint of Dissimilar Steels after Hot Stamping

采用激光填丝的方法对带有Al Si镀层的22MnB5和6Mn6异种热成型钢进行了拼焊,并对焊缝进行了焊后热成型实验。通过金相显微镜、维氏硬度计和拉伸试验机对热成型前后焊缝截面的宏观形貌、显微组织、硬度和拉伸性能进行了观察和测试。结果显示,在本文所提供的焊接参数条件下,可以获得焊缝成形良好的接头,且在拉伸测试中均断裂于6Mn6母材一侧(热成型后)。焊缝组织在热成型前后均以粗大的板条马氏体为主。Al Si镀层在焊接过程中被卷入焊缝形成带状和块状的富铝相,并在热成型后形成条块状分布的δ铁素体,但未导致接头在拉伸测试中断于焊缝。焊后母材硬度均低于200 HV,焊缝则在500 HV左右;热成型后焊缝硬度下降至370 HV左右,22MnB5母材上升至500 HV左右,6Mn6母材则在250 HV左右。

The welding of 22 MnB5/6 Mn6 dissimilar hot stamping steels with Al Si coating was carried out by laser welding with filler metal and then the hot forming process of weld seam after welding was implemented.By using the metalloscope,Vickers hardness tester and tensile test machine,the macro morphology of cross section of weld seam,microstructure,hardness and tensile properties of joints before and after hot forming were observed and measured.The results show that under the parameter in this paper,the joint with better welding formability can be achieved.After hot forming the joints fracture at the side of 6 Mn6 base metal in the tensile test.The microstructure of weld before and after hot forming is mainly martensite.The rich Al phase with block and band shape in the weld is formed by Al Si coating drifting into the weld,which transforms into block and band shapeδferrite after hot forming process.However it doesn’t cause the joint to fracture at the weld in the tensile test.Before hot forming,the hardness of base metals is lower than 200 HV,and the weld hardness is around 500 HV.After hot forming,the hardness of weld decreases to 370 HV,and the hardness of 22 MnB5 and 6 Mn6 base metals increases to 500 HV and 250 HV,respectively.