Study on microstructure and diffusion treatment of vacuum brazing joints of stainless steel

1Cr18Ni9Ti stainless steel is vacuum-brazed with brazing filler metal BNi-2 and BNi-5. The microstructure, phase composition and the microstructure after diffusion treatment of vacuum brazing joints are analyzed by metallographic analysis and X-ray diffraction. The results show that diffusion of constituent element between brazing filler metal and base metal occurs obviously. The compound phases of BNi-2 brazed joint are composed of CrB, SiB6, CrB2, Cr5B3 and Fe4.5Ni18.5B6. The compound phases of BNi-5 brazed joint are composed of FeNi, Cr3Si and CrB2. Diffusion treatment can entirely eliminate compound phase and promote the homogenization process of microstructure.