Experimental investigation on Ytterbium fiber laser butt welding of Inconel 625 and Duplex stainless steel 2205 thin sheets

摘要

In this study, welding of Superalloy Inconel 625 and duplex stainless steel 2205 (DSS 2205) has been successfully performed through Ytterbium fiber laser at different heat inputs. With decreasing energy input, width of the weld bead narrowed and the mechanical properties of the joint improved. Characterization of the weld joint was carried out using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and micro-hardness testing. No solidification cracks or porosity was observed in the microstructure of the weld metal (WM). Cellular dendritic and columnar dendritic grains were main grain types observed in the weld metal. At heat input of 43 J/mm, inter-dendritic arms of the weld metal witnessed more segregation of Molybdenum and Niobium in comparison of welded samples at heat input of 21.5 J/mm. Carbides of Cr, Mo and Ni are formed in the weld joint interface as revealed by the XRD analysis. Tensile strength study reveals the maximum strength of 890 MPa when the heat supplied is low i.e. 21.5 J/mm. This strength value is more than that of the base metal (DSS 2205). The result obtained in terms of comprehensive structure-property correlation, recommends the effectiveness of laser beam welding for joining of the said dissimilar alloys.