Abstract
Microstructures and joint strengths of SUS316 steel brazed with Cu-7P filler were investigated. When Cu plating treatment was performed on the surface of SUS316 steel over 15 μm, the reaction of SUS316 steel and Cu-7P filler didn’t occur so that the formation of the harmful Fe-P compound was prevented. These brazed samples showed excellent joint strengths as same as a conventional SUS316 joint brazed with pure Cu. On the other hand, when the molten Cu-7P filler reacted on SUS316 steel directly, the Fe-P-Cr-Ni compound formed at the brazed interface. This compound contains approximately 40 at% Fe and 40 at%P. The Vickers hardness of the Fe-P-Cr-Ni compound was evaluated as 522, which is approximately three times that of SUS316 steel. When the brittle Fe-P compound forms at the brazed interface, the joint strength decreases because the brittle fracture becomes to occur easily at the brazed interface.
