激光-电弧复合焊接高强钢显微组织与力学性能

摘要

为解决传统手工方法焊接高强钢时存在的焊接效率低、污染严重和变形大等问题,采用激光-电弧复合焊和CO2气体保护焊2种焊接方式焊接了1000 MPa级高强钢钢板,分别利用光学显微镜(Optical Microscope, OM)和X射线衍射仪(X-Ray Diffraction,XRD)对焊缝显微组织和晶体结构进行了表征,利用显微硬度计和拉伸试验机对力学性能进行了测试.结果表明:与CO2气体保护焊相比,激光-电弧复合焊工艺简单,效率更高;2种焊缝的微观组织均为奥氏体柱状晶,但激光-电弧复合焊焊缝组织晶粒尺寸更小;激光-电弧复合焊焊缝硬度及拉伸强度均高于CO2气体保护焊;2种焊接方式拉伸试样断裂均发生在焊缝中心,其中CO2气体保护焊焊缝中形成的碳化物、氧化物夹杂更多,在受到外力作用时更易萌生裂纹.%In order to solve the problems of low welding efficiency,serious pollution and large deformation in the welding of high strength steel by traditional manual methods,1 000 MPa high-strength steel plate is welded by two methods of laser-arc hybrid welding and CO2gas shielded welding. The microstructure and crystal structure of the welding bead are characterized by Optical Microscope (OM) and X-Ray Diffrac-tion (XRD). The mechanical properties are tested by microhardness tester and tensile tester. The results show that compared with CO2gas shielded welding,the laser-arc hybrid welding is simpler and more effi-cient;microstructure of both welding beads is austenite columnar crystal,while the grain size of laser-arc hybrid welding beads is smaller;the microhardness and tensile strength of laser-arc hybrid welding beads are both higher than that of CO2gas shielded welding beads;the fracture of tensile sample by two methods occurs at the weld center;CO2gas shielded welding beads are more likely to fracture due to the higher content of carbide and oxide in the welding beads.