In the present study a pulsed Nd:YAG laser with a maximum average power of 400 W and a 250 A tungsten inert gas (TIG) electrical arc were used as two combined heat sources in hybrid laser arc welding (HLAW). The effect of distance between heat sources, was investigated and the optimum distance selected. Laser beam welding (LBW) and TIG welding parameters were considered constant. The microstructure, microhardness and weld bead profile of stainless steel 1.4418 welded were investigated using HLAW, LBW and TIG in the same setting. The influence of heat input on weld pool geometry was surveyed. The results showed that penetration of HLAW doubles that of TIG and were five times that of LBW. Also the grain size in the heat affected zone (HAZ) in TIG was obviously coarse. In the fusion zone, the coaxial grains exist, which the size was the smallest in LBW and was the largest by TIG.
