Effect of bonding temperature on microstructure and properties of TLP joined Q355 steel with Cu interlayer

Abstract

Q355 steel with Cu interlayer was bonded by transient liquid phase diffusion bonding (TLP-DB) at different bonding temperatures, and good bonding joints were obtained. The joints were characterized by optical microscopy, scanning electron microscopy and mechanical properties. The results show that there is a bending phenomenon caused by the difference of element diffusion at the bonding interface at the bonding temperature of 1050 °C. With the increase of the bonding temperature, the diffusion of Cu element plays a role in refining the grain, but with the increase of the bonding temperature, it will also lead to the overgrowth of the grain; At the bonding temperature of 1050 °C, there are obvious mutations in the diffusion of Cu and Fe elements, but the increase of the bonding temperature has a good effect on the interdiffusion of the elements. The mechanical properties test showed that with the increase of the bonding temperature, the hardness, shear strength, and impact toughness at the center of the joint increased first and then decreased, and all reached the maximum at 1100 °C. The electrochemical performance test showed that with the increase of temperature, the corrosion resistance of the joint also increased first and then decreased.