Microstructure and mechanical properties of diffusion bonding joints of 42CrMo steel and tin bronze with nickel interlayer

Abstract

Diffusion bonding technology was used to realize the connection of 42CrMo steel and tin bronze, and the effects of bonding time and nickel interlayer on the microstructure and mechanical properties of the joint were studied. The results show that: When 42CrMo steel and tin bronze are directly diffusion bonded, at 850 ℃ and 4MPa, the shear strength of joint first increases and then decreases with the increase of bonding time. When the bonding time is 60 min, the thickness of the diffusion layer is about 0.5μm, the shear strength of the joint reaches a maximum of 152MPa, and the fracture shows mixed fracture characteristics of brittleness and ductile. After adopting Ni foil as the interlayer metal, both 42CrMo steel/Ni and Ni/tin bronze interfaces formed obvious diffusion layers of about 11 μm and 50 μm, respectively, a granular discontinuous distribution of (Cu,Ni)3Sn formed on the Ni/tin bronze side, the shear strength of the joints is elevated up to 221 MPa, and the fracture is characterized by ductile fracture.