Bi黄銅とステンレス鋼の低温ろう付

抄録

Brass alloys are used in products such as piping components and machine parts because of their excellent workability. In addition, brazing between dissimilar metal materials such as brass and stainless steel is performed during manufacturing. In recent years, due to stricter lead regulations, Pb–free free–cutting brass with Bi or Si added as an alternative element has been developed and put into practical use. Previous studies have shown that additive elements such as Bi and Si affect brazeability. In this study, Bi–containing brass was used for brazing with stainless steel SUS304, and the effect of brazing temperature on the interfacial reaction was investigated in detail. Furthermore, we aimed to clarify the interface reaction mechanism during brazing at relatively low temperatures and to obtain sound brass/stainless steel brazed joints. To evaluate brazeability, the cross–sectional microstructure was observed and elemental analysis by EPMA was performed.
As a result, brazing of brass/stainless steel at low temperatures was possible. Brazed layer was formed, but voids were observed in various places. This may be due to insufficient interfacial reaction between the molten brazing material and the stainless steel surface. Elemental analysis by EPMA showed that Ag melted and diffused to the brass side at each temperature. Localized precipitation of Bi was observed in the Ag–rich phase in the brazed layer. It is concluded that Bi has no effect on brazeability at the temperatures within this experiment.