Investigating the effect of process parameters on weld pool thermal history and mechanical properties of laser welded Inconel 625 and Duplex stainless steel 2205 dissimilar welds

In present study, welding of Inconel 625 and 2205 grade duplex stainless steel (DSS 2205) was carried out using a 2 kW Yb-fiber laser. An infrared (IR) pyrometer was used to log the thermal history of the weld pool. The molten weld-pool lifetime and cooling rates were accessed through the recorded data, and their effect on microstructure, elemental segregation, hardness and tensile properties of welded joints was investigated. The weld bead was composed of columnar and equiaxed dendritic grains. The microstructure exhibited refinement with increase in cooling rate, reducing the micro-segregation of Molybdenum (Mo) and Niobium (Nb) in the inter-dendritic spacing which was further investigated through XRD analysis. Also, tensile strength was found to be maximum i.e., 896.4 ± 8.1 MPa in the samples welded at 1950 W, 5500 mm/min which exhibited the fastest cooling within the range of parameters selected.