Influence of advanced laser-arc hybrid welding and conventional MIG process on microstructure, mechanical properties and corrosion resistance of dissimilar joints

The purpose of this paper is to study the technological potential advantages and quality of dissimilar metal (austenitic stainless steel and ferritic stainless steel) joint welded by advanced laser-arc hybrid process and compared it with a conventional metal inert gas welding process on key grounds like weld geometry, structure-property co-relationship, in order to encourage its industrial recommendation for this dissimilar metal combination. The characterization was accomplished by using an optical microscopy, scanning electron microscopy and energy dispersive spectrometer. Results indicated the full depth of penetration in both the processes; however, narrower weld bead and absence of heat affected zone achieved with laser-arc hybrid welding. Equiaxed dendritic microstructure comprised of massive acicular ferrite was observed in laser-arc hybrid welding, while, in case of metal inert gas welding process, cellular dendritic microstructure and type-II boundary was examined. Laser-arc hybrid welding showed higher hardness, higher tensile strength and low impact energy due to rapid cooling rate. Magnetic induction method (ferritoscope) revealed higher ferrite content in the laser-arc hybrid welding process. The modified strauss test revealed intergranular corrosion in the ferritic base metal.