Investigation the effect of dissimilar laser welding parameters on temperature field, mechanical properties and fusion zone microstructure of inconel 600 and duplex 2205 stainless steel via response surface methodology

This study focused on dissimilar welding characterization of Inconel 600 and duplex 2205 stainless steel using central composite design (CCD) of experiments the response surface methodology (RSM). This study determined the effect of laser welding parameters and the reactions of the temperature field on the melt pool, the mechanical characteristics of the weld joint, and the geometry of the melt pool. According to the ANOVA results, the power of laser and focal distance were found to be the most influential factors on the temperature of both Inconel 600 and duplex stainless steel. The weld joint's tensile strength and elongation were significantly influenced by laser power and focal distance. Increasing the laser power from 250 to 450 W raised the tensile strength from 250 to 550 MPa. The Mo rich phases formed at the inter-dendritic region according to the EDS phase analysis results in loss of ductility and the resultant tensile strength of the samples failure from the fusion zone adjacent to the duplex stainless steel. At high laser power levels, the samples fractured from fusion zone while at lower laser powers below 350 W, the samples fractured from the HAZ and the areas adjacent to the duplex steel fusion line. The micro-hardness value of the weld joint at different laser power of 525 W and 375 W was increased to the maximum values of 370 and 325 HV, respectively from the fusion line of Inconel 600 to the center of the fusion zone. Further, molten pool microstructure of the dissimilar joint zone was mainly composed of a cellular and columnar dendritic structure Variations in melt flow, temperature gradient and solidification rate from the molten scan line to the weld center clearly changed the grain growth and the resultant microstructure in different areas of the fusion zone. By transferring the laser light to the center of the Inconel 600 and duplex stainless steel joint, the molten pool depth was increased from 0.2 to 1.5 mm.