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.