Abstract:Electron beam welding (EBW) of 304 stainless steel to QCr0.8 copper alloy with copper filler wire was carried out. Orthogonal experiment was performed to investigate the effects of process parameters on the tensile strength of the joints, and the process parameters were optimized. The optimum process parameters are as follows: beam current of 30 mA, welding speed of 100 mm/min, wire feed rate of 1 m/min and beam offset of -0.3 mm. The microstructures of the optimum joint were studied. The results indicate that the weld is mainly composed of dendritic α phase with little globular ε phase, and copper inhomogeneity only occurs at the top of the fusion zone. In addition, a melted region without mixing exists near the weld junction of copper side. This region with a coarser grain size is the weakest section of the joints. It is found that the microhardness of the weld decreases with the increase of the copper content in solid solution. The highest tensile strength of the joint is 276 MPa.

Key words: 304 stainless steel; QCr0.8 copper alloy; electron beam welding; dissimilar joint; mechanical properties