中部槽激光-MAG复合热源打底焊焊接工艺研究

Back welding process of central groove based on laser-MAG hybrid welding method

采用MAG电弧焊和激光-MAG复合热源焊对45 mm厚ZG30SiMn和NM400异种钢进行打底焊试验,通过光学显微镜、SEM和EDS能谱分析方法对裂纹的微观组织形貌进行观察和分析。结果表明:中部槽焊接接头易出现未焊透和焊接裂纹等焊接缺陷。由于焊缝处C,Si,S,P等热裂纹敏感性元素的聚集及焊接应力的共同作用导致结晶裂纹的产生。采用激光-MAG复合热源焊,通过控制焊缝化学成分和改变接头形状的方法消除了焊接热裂纹,并利用复合热源深熔性特点结合焊接坡口优化,保证了焊接效率等问题,获得了稳定、优质、高效的焊接接头。

By manual MAG welding process,back welding experiment dissimilar steel of central wear- resisting plate of the central groove of ZG30 SiMn casting ledge to the NM400 of 45 mm in thickness was conducted.The result showed that incomplete penetration and weld cracking appear in joints.By analyzing the microstructure,SEM and EDS spectrum scanning of fracture of the cracks,these cracks were recognized as solidification cracks,and their main cause are the existence of high hot cracks susceptible elements such as C,Si,S,P and the others,and the effect of welding stress.Laser- MAG arc hybrid welding method was used to eliminate hot cracks by controlling the chemical composition of the weld and reducing welding stress concentration.By combining the characteristic of deep penetration of laser- arc hybrid welding with the groove structure optimization,it solves successfully the above problems,and finally the stable,high- quality and efficient welded joints were obtained.