Effect of post-weld heat treatment on microstructure and mechanical properties of induction pressure welded joint for A283GRC steel and 5052 aluminum alloy

Abstract

To further enhance the mechanical characteristics of the induction pressure welding (IPW) joint, the heat treatment was carried out for the IPW joint of A283GRC steel and 5052 aluminum alloy plates. The effect of annealing time and annealing temperature on the microstructure and properties of IPW joint was considered in the process of post-weld heat treatment (PWHT). The outcomes demonstrated that PWHT can successfully increase the shear strength of the welding joint under IPW. When the annealing temperature was 300 ℃ and the annealing time was 2 h, the shear strength of the joint reached 51.56 MPa, which was increased by 84 % compared with that before heat treatment, and the maximum improvement effect was achieved. PWHT had no effect on the intermetallic compounds (IMCs) type of IPW joint, and the interface was still composed of tongue Fe2Al5 and serrated FeAl3. PWHT increased the degree of component interpenetration at the steel-aluminum alloy contact, which can both raised the IMCs' thickness and uniformly distribute the chemical make-up of the interface IMCs. The cracks near the aluminum alloy side of the joint were gradually repaired and healed with the increase in annealing temperature and the extension of holding time. After heat treatment, the grain was finer close to the steel side of the joint, which was conducive to the increase of the strength of the joint. Increasing the annealing temperature and time, the IPW joint's shear strength increased at first, then declined. In the time and temperature range examined, annealing temperature had a bigger impact on the joint's shear strength than annealing time did. At the fracture, PWHT resulted in a significant number of large-area equiaxed dimples. The mixed fracture mode, which was predominately brittle fracture without heat treatment, transforms into another mixed fracture mode, which was predominately ductile fracture after heat treatment.