Experimental studies on laser beam welding of austenitic stainless steel to low carbon steel joint

Abstract

Laser welding is an advanced joining method because of its narrow heat affected zone high power density high welding speed fine microstructure and low distortion resulting in high strength and ductile properties Typically the quality of a dissimilar weld joint is directly influenced by the laser welding process parameters during the welding process Welding of dissimilar metals is one of the challenging and emerging fields of research as it involves in minimizing the use of high cost materials Dissimilar metal joining of austenitic stainless steel AISI 316 and low carbon steel AISI 1018 are extensively used in nuclear reactors pressure vessels boilers and heat exchangers of power generation industries and petrochemical plants. In the present study the laser welding of AISI 316 austenitic stainless steel and AISI 1018 low carbon steel was carried out at various thicknesses of 2 mm sheet and 6 mm plate joint Welding trials were performed as per Taguchi L9 orthogonal array design with three parameters at three levels The dissimilar butt joint trials were carried out, using 4 kW CO2 laser welding by varying the laser power W welding speed m min focal distance mm and constant shielding gas flow rate 20 Lit min for 2 mm sheet joining Similarly the dissimilar 6 mm plate welding is carried out varying of laser power W welding speed m min shielding gas flow rate Lit min and constant focal distance 20 mm The varying laser welding process parameters were used to study the effect of the mechanical and metallurgical properties of the dissimilar sheet and plate joint The optimum parameters have been derived by considering the responses of tensile strength and hardness of the dissimilar weld joint newline