Analysis of the thermal expansion and mechanical properties of laser cladding of Invar alloy

Laser cladding has significant advantages in the forming process of Invar alloy. Nevertheless, the coefficient of thermal expansion, microstructure and mechanical properties still need to be further investigated. In this paper, the Invar alloy powder was used to prepare cladding samples, and the performance and microstructure of the cladding layer were investigated. The mechanical and thermal expansion performances of the cladding layer were analysed using a universal material testing machine and a thermal expansion instrument, and the microscopic structure and micro zone composition of the tensile fracture of the cladding layer were investigated using an SEM scanning electron microscope and an EDS energy spectrum analyser. The results show that the mechanical properties of the Invar alloy transverse cladding layer are better than those of longitudinal cladding layer; the thermal expansion performance of the cladding layer is good, and it keeps the same with the base material in the range of 25–200 °C; the fracture analysis reveals more dimples in the transverse cladding layer fracture with better plastic tenacity, and intergranular fracture and quasi-cleavage fracture in the longitudinal cladding layer fracture with slightly poor plastic tenacity.