Weld microstructure and shape of laser - arc hybrid welding

A series of CO2 laser-metal inert gas arc hybrid welding experiment was carried out to investigate the effects of laser/arc energy ratio and groove parameters on the shape and microstructure of hybrid weld. The results showed that increasing arc current and groove cross-section area can reduce dimension difference of laser zone and arc zone by enhancing the uniform of energy distribution in molten pool. The arc current can speed the melted metal flow to the pool root and drive more heat to the pool below by the arc pressure, and groove area can reduce the resistance of melted metal flowing to the pool root. The microstructure of hybrid weld is simultaneously determined by the total line energy of hybrid welding and energy ratio of laser/arc (ERLA), and only under the proper or relatively smaller total line energy ERLA has obvious effects on microstructure. Increasing the ERLA can increase the tendency of hybrid weld to obtain structure with higher hardness. Furthermore, the mechanical performance of the hybrid weld with lower ERLA is good.