Sung Hwan Kim¹, Ji-Hwan Cha¹, Changheui Jang¹; ¹Korea Advanced Institute of Science & Technology

Diffusion bonding is a key technology for fabrication of compact heat exchangers such as the printed circuit heat exchanger (PCHE), which would be applied in next generation nuclear power plants. Meanwhile, appropriate selection of structural materials is necessary in consideration of specific operating conditions for each system. Thus, in this study, diffusion bonding of various Fe- and Ni-base alloys have been conducted and the effect of bonding parameters on joint efficiency have been evaluated. It was found that diffusion-bonded 300-series austenitic stainless steels had comparable tensile properties to the as-received condition. On the other hand, diffusion-bonded Ni-base alloys exhibited low tensile ductility due to premature brittle failure at the bond-line especially at elevated temperatures. Application of post-bond heat-treatments seemed to somewhat improve the elongation of these joints. Preliminary results on effect of Ni-interlayer insertion on diffusion-bond integrity of Ni-base alloy joints are also discussed.