Effect of the post-weld heat treatment temperature on the mechanical properties and microstructure of magnetic pulse welded Al/Fe tubes

Post-weld heat treatment (PWHT) can improve the microstructure and properties of welded joints. Here, the effect of the PWHT temperature on the microstructure and mechanical properties of Al/Fe tube joints manufactured by magnetic pulse welding (MPW) was investigated systematically. The results indicated that PWHT improved the distribution of the chemical composition in the thick transition layer (thickness >10 μm), with only a slight change in thickness. In contrast, the thickness of the thin transition layer (thickness ≤10 μm) increased significantly upon increasing the temperature. Micropores, radial cracks, and axial cracks were repaired to different degrees below 250 °C, but axial cracks propagated in the axial direction when the temperature exceeded 250 °C. The local shear strength 3 mm from the free end reached about 58 MPa, which was almost two times greater than that without PWHT at 250 °C. Once this temperature was exceeded, the shear strength decreased; thus, the optimal PWHT temperature was 250 °C, at which the microstructure and mechanical properties were improved better.