Effect of Brazing Temperature on Microstructure and Mechanical Property of High Nitrogen Austenitic Stainless Steel Joints Brazed with Ni-Cr-P Filler

摘要

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_2N compounds are formed at the HNS/filler interface when the brazing temperature is lower than 1 000℃. The brazing seam is composed of Ni-Fe solid solution and (Ni, Cr)_3P compounds, and the content of (Ni, Cr)_3P compounds decrease with the increasing of brazing temperature. The formation of Cr_2N and (Ni, Cr)_3P 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℃.