Study on the Influence of Surface Roughness and Temperature on the Interface Void Closure and Microstructure Evolution of Stainless Steel Diffusion Bonding Joints

Abstract

Austenitic stainless steel diffusion bonding was performed, and the effects of the surface roughness and bonding temperature on the interface microstructure and mechanism of hole closure were investigated. The bonded interface microstructure was analyzed. The influence of surface roughness and temperature on cavity evolution, bonding rate, and axial deformation rate was studied. The mechanism of interfacial void closure in the stainless steel diffusion bonding process was revealed. With the increase in temperature and the decrease in surface roughness, the size of the interface void and the bonded area decreased. The bonding rate can reach more than 95% when the surface roughness value is 0.045 μm and the temperature is at or higher than 750 °C. The analytical equations of interfacial bonding rate δ and axial deformation rate ε produced by the deformation mechanism were established, and the laws of the deformation mechanism and diffusion mechanism within interfacial hole closure were obtained.