Low cycle fatigue strength of diffusion-bonded joints of alumina-dispersion-strengthened copper to 316 stainless steel

Low cycle fatigue tests were performed for 316 stainless steel (316SS), alumina-dispersion-strengthened copper (DS Cu) base metal and 316SS-DS Cu diffusion-bonded joints. Plastic strain distribution of joint specimens during fatigue was measured to estimate deformation of the joint specimens. Furthermore the microstructure of the diffusion zone of the joints and fracture surface of the fatigue specimens were examined with scanning and transmission electron microscopes. Intermetallic compounds and recrystallization of DS Cu were observed near the interface in DS Cu. The fatigue life of the joints was lower than that of DS Du. The joint specimens fractured in the DS Cu near the interface in the case of low strain range fatigue tests. For high strain range fatigue tests, however, the fracture point was in the DS Cu 6-7mm from the interface, at which the maximum plastic strain occurred. (author)