Influence of beam current on microstructures and mechanical properties of electron beam welding-brazed aluminum-steel joints with an Al5Si filler wire

Exploratory experiments of Electron beam welding-brazing (EBW-brazing) of 304 stainless steel (304 SS) to commercial pure aluminum (CP-Al) with an Al5Si filler wire under different beam currents were carried out. The microstructural characteristics of the joints were analyzed by SEM and XRD methods. Tensile strengths and nanoindentation were performed to evaluate the mechanical properties of the joints. The results indicated that beam current affected the thickness of the IMC layer and weld appearances, then further affected the tensile strengths of joints. The major intermetallic compound (IMC) formed at the connection layer was determined to be Al8Fe2Si with a Young's modulus of 223.2 GPa and nanohardness of 9.5 GPa. The highest tensile strength of the joints was 93 MPa under an optimum welding parameter, which was approximately equal to 83% of that of CP-Al.