Influence of annealing on the microstructure and mechanical properties of Ti/steel clad plates fabricated via cold spray additive manufacturing and hot-rolling

A novel method was designed to fabricated Ti/steel clad plates via cold spray additive manufacturing (CSAM) and hot-rolling. In order to study the influence of annealing on the microstructure and mechanical properties of the Ti/steel clad plates, the as-rolled clad plates were subjected to different annealing temperatures in the order: 450, 550 and 650 °C. It was revealed that CSAM and hot-rolling promote metallurgical bonding between Ti/Ti as well as Ti/steel interfaces, thus resulting in Ti/steel clad plates with excellent mechanical properties. The annealing treatment promotes inter-diffusion of Ti and Fe across the Ti/steel interface and improves the microstructures of the as-rolled Ti/steel clad plates. The results show that when the annealing temperature is low (i.e. 450 °C), the elongation of the specimen increases while the ultimate tensile strength and shear strength both decrease through recovery and recrystallization mechanisms. However, when the annealing temperature is too high (i.e. 650 °C), the elongation and strength of the specimen decrease sharply due to the nucleation and growth of brittle TiC and FeTi compounds. The annealing, at 550 °C for 3 h, was pin-pointed as the optimum post-rolling treatment to achieve superior ultimate tensile strength (564 MPa), shear strength (280 MPa) and elongation (18%) in the clad plate.