Study on Diffusion Bonding Characteristics of Austenitic Stainless Steels

This study was conducted by using type 304 austenitic stainless steel as experimental material to clarify the diffusion characteristics of diffusion bonding and diffusion brazing. The bonding variables such as the bonding pressure, bonding time and surface roughness affecting the tensile behavior of joints. The main results obtained were as follows: The tensile strength of diffusion bonded joint was almost equivalent to that of the base metal, and the joint efficiency of almost 100%. Although the surface roughness did not have significant influence on the tensile strength of diffusion bonded joints, it shows notable difference in terms of the fracture appearance. The fracture occurred in the interface of bonded joints when the surface roughness was not so smooth. However, all of the tensile specimen fractured at base metal and showed typical a cup and cone fracture, when the surface was smooth. The pressure was an extremely critical factor when conducting diffusion brazing. It was observed that as the pressure became higher, the better interface was produced, showing high quality interface with the tensile strength of the joints amounting to nearly 500MPa. The homogenization heat treatment after diffusion brazing had some influence on the strength of joints. Key words: Diffusion bonding, Diffusion brazing, Homogenization, Surface roughness, Tensile strength