Dissimilar joining of carbon steel, pure nickel and aluminum alloys by center-driven double-sided linear friction welding

In this study, a center-driven double-sided linear friction welding (LFW) process was employed to join three dissimilar materials: A7075-T6, S45C, and pure Ni. High pressure was applied to the A7075-T6 side, as it was intended to be joined at a low temperature, while low pressure was applied to the S45C side, which needed to be joined at a high temperature. By setting the applied pressure on the A7075-T6 side to 300 MPa, which corresponds to the intersection in the graph of the strength dependence of A7075-T6 and pure Ni on temperature, the joint with a joining efficiency of 92% was obtained. SEM and TEM observations were carried out on the joint, confirming the absence of the welding defects at both the A7075-T6/Ni and Ni/S45C interfaces. A thin intermetallic compound layer of approximately 100 nm thick was formed at the A7075-T6/Ni interface.