Experimental investigation on mechanical and microstructural properties of AISI 304 to Cu joints by CO2 laser

Aim of the present work is to investigate mechanical and metallurgical characteristics of continuous wave CO2 laser welded dissimilar couple of AISI 304 stainless steel and commercially pure copper sheets in autogenous mode. Metallurgical analysis of the fusion zone has been done to understand the mixing and solidification behavior. Macroscopic examination has been carried out to observe the macro-segregation pattern of Cu, Fe and Cr rich phases in different zones, and the thickness of HAZ was found to be around 10 µm. The micro-channels formed from the steel side to weld pool describe that the copper solidifies first and provides the nucleation surface for the residual melt to grow. These tubular micro-channels formed may be due to carbide precipitation. The EDS analysis conforms the well mixing of SS and Cu inside the weld pool. The mechanical properties in terms of tensile stress found up to 201 MPa and the fracture are obtained outside the weld zone. Microhardness measurements over the fusion zone have been done to understand the keyhole growth and quenching, solidification sequence and stress distribution over the full area.