Cast iron is a metal material which extensively used in modern industry .It has excellent processing property and service performance with easy processing and low cost, so it is used in many industry fields such as mechanical manufacture, metallurgy, mine, petrochemical, traffic and transport, architecture and defence. As to many mechanicals,the weight of cast iron is 45%~90% that of the machine.However, cast iron easily causes cracking and gas cavity, so laser wire-feeding overlaying welding in cast iron is limited in application. Through analyzing surface quality,microhardness and wear-resistance,this paper studied the processing of laser overlaying welding and optimized the processing parameters. The optimum parameters were:P=2.8~3.5kW,Vs=0.15-0.22 m/min,Vf=0.30 — 0.40 m/min.Afterlasertreatment,the surface obtained fine microstructure,even composition and high hardness. The Ni-based transition alloy had a function of dispersion strengthening, and ahvanced the toughness, reduced the trend of cracking. The multi-layer laser overlapping welding was applied in thick repair of cast iron dies and acquired excellent effect.
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