Autogenous Dissimilar Welding of Copper-to-Stainless Steel via Electron Beam Welding: A Novel Strategy for Achieving Defect-Free Joints

Autogenous dissimilar welding of oxygen-free copper to austenitic stainless steel AISI316 was successfully performed by electron beam welding (EBW) using strategic base metal plate tilt of 22 deg and beam shift. The effect of focus distance, beam current, and travel speed on the tensile strength, percent elongation, and impact strength of the welded joints was investigated. The maximum tensile strength was achieved to be 282 MPa at a focus distance of 20 mm, a beam current of 40 mA, and a travel speed of 400 mm/min. Elemental integrity was examined through a continuous energy-dispersive spectroscopy (EDS) scan across the joint for all the welded samples. It was observed that the concentration of elements Fe, Cr, and Ni increased, and that of Cu decreased from the copper region to stainless steel (SS) in the weld zone. The microstructures and microhardness profile of the welded joint were studied. A lower microhardness value was present in the weld region due to a higher fraction of Cu in the weld compared with that of SS. Thus, the balance of energy over the dissimilar materials effectively allowed autogenous welding of a pair of materials which is challenging to join.