球铁光纤激光-MIG复合焊接头的裂纹倾向与力学性能

以308L不锈钢焊丝作为填充材料，采用光纤激光-MIG电弧复合焊在5mm厚的球墨铸铁上进行焊接，重点关注了工艺参数对裂纹倾向的影响，获得了成形良好且无裂纹的焊接接头．结果表明，随着激光功率的减小和电弧电流的增加，接头熔合比减小，裂纹倾向降低．接头显微硬度和组织的分析结果表明，由熔合比带来的碳含量变化是影响裂纹倾向的直接原因．在厚度10mm的球墨铸铁试件上开X形坡口进行多层多道焊，所得焊接接头的强度和断后伸长率分别为母材的73％和20％，接头断裂机制为脆性断裂，半熔化区的莱氏体是造成断裂的原因．

Crack tendency and mechanical properties of ductile cast iron joint by fiber laser-MIG hybrid welding

Fiber laser-pulsed MIG hybrid welding of 5 mm-thick ductile cast iron sheet was conducted with 308L stainless steel wire as the filler metal.The effect of welding parameters on cracking tendency was discussed, and joints with good formation and no cracks were obtained.The results showed that penetration ratio decreased with increasing welding current and decreasing laser power, which subsequently decreased the crack tendency.Based on hardness and microstructure analysis, the change of carbon content induced by penetration ratio was the direct reason for crack tendency.Multi-layer and multi-pass welding was carried out on 10 mm-thick ductile cast iron plate using the optimized parameters, and the tensile strength and elongation of the resultant joints reached 73% and 20% of those of the base metal, respectively.The existence of ledeburite in partially melting zone resulted in the brittle fracture of the joints.