船用钢板T型接头CO_2激光电弧复合焊工艺与组织分析

CO2 Laser-MIG Hybrid Welding Process and Microstructure of T Type Joint of Shipbuilding Steel Plate

采用高功率CO2激光电弧复合焊方法对14mm厚的CCS-A船用钢板进行了熔透型T型接头的双面焊接。通过工艺参数优化,获得了焊缝成形质量良好的T型接头,焊缝共2道。工艺试验表明,接头不开坡口可降低焊缝咬边缺陷倾向;较小的激光束与面板的夹角可获得较大的熔深。光学显微镜观察发现,在焊缝区和热影响区均有马氏体组织形成,其中细晶区主要为细小马氏体。焊接接头硬度测试显示,接头最大硬度在细晶区。T型接头第二面焊接对第一面焊接有回火作用,使其硬度降低,最终焊接接头的最大硬度小于380HV。

CCS-A shipbuilding steel with 14 mm thickness was welded in T-type joint form from two sides by CO2 laser-MIG hybrid method with full penetration.Through optimizing process parameters,the T type joint with good weld forming quality was acquired,two welding passes were made.The process testing shows that T type joint without groove has less tendency to undercut than that with groove.With a lower angle between laser beam and bottom plate,a deeper penetration could be achieved.The results show that the martensite appears in welded joint,especially in fine grain zone,the main phase is fine martensite.The highest hardness occurs in the fine grain zone.Due to the tempering effect of the second weld pass on the first pass,the maximal hardness of T type joint is less than 380 HV.