Effect of brazing temperature on microstructure and mechanical property of high nitrogen austenitic stainless steel joints brazed with Ni–Cr–P filler

Abstract

In this study, Ni–Cr–P filler was used for vacuum brazing of high nitrogen austenitic stainless steels (HNS). The microstructure and shear strength of HNS joints were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD) and universal testing machine. The results exhibit that Cr 2 N compounds are formed at the HNS/filler interface when the brazing temperature is lower than 1 000°C. The brazing seam is composed of Ni–Fe solid solution and (Ni, Cr) 3 P compounds, and the content of (Ni, Cr) 3 P compounds decrease with the increasing of brazing temperature. The formation of Cr 2 N and (Ni, Cr) 3 P compounds is adverse to the joint strength due to their brittleness. The optimal shear strength of joints is 163 MPa when the brazing temperature is 1 050°C.