Influence of an AlSi5 filler wire on microstructures and mechanical properties of EBW-brazed CP-Al to 304 SS joint

Electron beam welding-brazing experiments of commercial pure aluminum (CP-Al) to 304 stainless steel with and without an Al-Si5 filler wire were carried out. Si element existing in the filler wire could help to improve the wettability of aluminum on steel and formed a continuous interfacial IMC layer of Al₈Fe₂Si. The interface of the joint without filler metal was characterized by a discontinuous Fe₂Al₅ compound layer with cracks in it. Meanwhile, the nanohardness and Young's modulus of Al₈Fe₂Si compound were both lower than those of Fe₂Al₅ compound. The tensile strength of the joint welded with filler wire was higher than that of the joint welded without filler metal. It implied that a continuous IMC layer with lower hardness is beneficial to improve the strength of the electron beam welding-brazed 304 SS to CP-Al joint.