Abstract: The wrought Al alloy-wrought Al alloy overcast joint was fabricated by casting liquid 6101 Al alloy onto 6101 Al extrusion bars and solidifying under applied pressure. The joint interfacial microstructure was investigated; the effect of applied pressure on the microstructure and mechanical properties was evaluated. The mechanism of joint formation and mechanical behaviors of both squeeze cast 6101 and 6101-6101 overcast joint material were analyzed. The results show that with the application of pressure during solidification process, wrought Al alloy 6101 could be cast directly into shape successfully. Excellent metallurgical bonding was then formed in the overcast joint by electro-plating 6101 solid insert with a layer of zinc coating, and a transition zone formed in the joint region. During the tensile test, the fracture occurs in the 6101 solid insert part with the ultimate tensile strength (UTS) of 200 MPa, indicating that the strength of the overcast joint is higher than 200 MPa, and the tensile strength of overcast joint material is independent on the magnitude of applied pressure. For Al-Al overcast joint material, if a clean and high strength joint is formed, the UTS and yield strength (YS) are determined by the material with the lower value, while for EL, the value is determined by the length proportion and the stress-strain behavior of both components.

Key words: Aluminum alloy, Overcasting, Squeeze casting, Interface, Microstructure, Mechanical properties