Role of surface roughness in impulse pressure diffusion bonding of dissimilar steels using copper interlayer

Abstract

Surface preparation is an important step in diffusion bonding that can’t be eliminated and compromised to achieve a good quality joint. Proper surface preparation becomes time consuming besides being laborious due to polishing requirements. In view of the above, P92 steel and 316L ASS rods were diffusion bonded using pressure pulses introducing copper interlayer and the effect of surface roughness was investigated. The developed bonded bonds were characterized in respect of hardness distribution, tensile properties, and scanning electron microscopy. The effect of surface roughness on joint strength was also studied. It was found that the diffusion bond consists the similar microstructural features as the base metal. However, some microvoids were found at the diffusion bond interface for the diffusion bonds developed at high surface roughness, which influences the mechanical property of the diffusion bonds and gets reduced with the decrease in surface roughness. Room temperature tensile tests were conducted and the tensile strength was found as 329, 372, and 413 MPa for three different surface roughness having failure from the copper interlayer.