Effect of post-bond heat treatment on the diffusion bonding properties of alloy 800H with Ni-foil interlayer

Abstract

A research was conducted on diffusion bonding which is key process required for manufacturing a printed circuit heat exchanger. In this study, diffusion-bonded alloy 800H with Ni foil interlayer was used, and the tensile and stress-rupture test were conducted after post-bond heat treatment. In the case of tensile properties, the grain boundary migration was promoted when post-heat treatment was applied. Thus, the elongation was improved at 650°C. Regarding stress-rupture test, rupture time is decreased when applying PBHT-A condition (1100 ℃, 10 h), and increased when applying PBHT-B condition (1200 ℃, 1 h). It is considered by the distribution of Ti-rich carbide of the joint. Changes in the mechanical properties were discussed through microstructure analyses.