Brazing stainless steel with high chromium nickel alloy

Abstract High-temperature brazing of dissimilar joints is an important task today for many industries, including aviation and energy, in the manufacture of critical components. This work presents the results of micro-X-ray spectral investigations of the interfacial boundary between the filler metal and the base metal after spreading of brazing fillers based on the Ni-Mn-Si-Cu and Cu-Ni-Mn-Co-Fe-Si-B systems on stainless steel 12Kh18N10T and heat-resistant nickel alloy KhN77TYuR. The influence of brazing temperature on the filler metal structure formation after spreading was determined. The features of the structure formation of brazed joints during high-temperature vacuum brazing of dissimilar joints between stainless steel and heat-resistant nickel alloy are shown. The results of local micro-X-ray spectral analysis demonstrated that when using the filler based on the Ni-Mn-Si-Cu system, the microstructure of brazed joints in dissimilar joints contains a solid solution and a eutectic component crystallized in the central zone of the brazed seam, which consists of a solid solution and nickel silicide. When using the Cu-Ni-Mn-Co-Fe-Si-B filler, needle-like chromium borides and nickel silicides crystallize along the grain boundaries of the solid solution in the brazed joint structure. The obtained results showed that reducing the silicon concentration (from 7–1%) in the filler and additional boron alloying provides an increase in shear strength up 176 to 315 MPa.