Brazing of Ferritic Stainless Steel and Microstructure At the Brazed Joint

Recently, brazing of ferrite stainless steel has been interested in, because of economical reason.  In this study, brazing of ferrite stainless steel with using typical Ni-based brazing filler metal was done under vacuum and/or Ar gas atmosphere.  Furthermore an interfacial reaction between ferrite stainless steel and molten brazing filler metal was investigated by elemental distributions at the brazed joint with EPMA examination.  SUS430J1L (JIS) was employed as base material.  And BNi-2, BNi-5, and Ni-Cr-Si-P brazing filler metals were used as BFM.  For the brazed joint having a wide clearance (about 100 - 500 micrometer), additional effect of Ni powder into powder type Ni-based brazing filler metal was investigated by observation of the cross-section at the brazed joint with using slope type specimen.  Sound brazed joints were observed in this study.  Typical brazed joint consisted of primary crystal Ni-based solid solution and eutectic microstructure containing intermetallic compounds.  And precipitation type alloy layer was formed between base material and primary crystal.  It was appeared that this alloy layer influenced the brazed joint properties.