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.

Microstructure and Properties of SUS304 Stainless Steel Joints Brazed with Electrodeposited Ni-Cr-P Alloy Coatings

“…The shear strength obtained in this study seems to be lower than the reported ones [ 14 , 15 , 16 , 17 ]. However, it is well known that there are many parameters that affect the shear strength of the brazed joint, such as the brazing temperature, the holding time at brazing temperature and the gap width of the joint.…”

“…Figure 10 shows the spontaneous potentials of SUS304, brazed Ni-11P alloy coating, and brazed Ni-13.4Cr-11.6P alloy coating measured in a 0.06 M/L NaCl solution. The The shear strength obtained in this study seems to be lower than the reported ones [14][15][16][17]. However, it is well known that there are many parameters that affect the shear strength of the brazed joint, such as the brazing temperature, the holding time at brazing temperature and the gap width of the joint.…”

“…However, it is well known that there are many parameters that affect the shear strength of the brazed joint, such as the brazing temperature, the holding time at brazing temperature and the gap width of the joint. Zhang et al [ 14 ] reported that the shear strength of the brazed joint increased from 60 MPa to 160 MPa with an increase in the brazing temperature. Li et al [ 15 ] studied the effect of gap width and holding time on the mechanical properties of the brazed joint.…”

“…In addition, Ni-based filler metal containing a certain amount of Cr (such as BNi-7) has been used to improve the heat resistance and corrosion resistance of the brazed joint. Many studies showed that the BNi-7 filler metal is suitable to braze stainless steel with a thin thickness owing to its excellent wettability and low melting point [ 14 , 15 , 16 , 17 ].…”

The Microstructure and Mechanical Properties of Multi-Strand, Composite Welding-Wire Welded Joints of High Nitrogen Austenitic Stainless Steel

“…Ogawa et al [4] reported that nitride precipitates after aging 2 s in the temperature range between 900 °C and 1100 °C at the welding heat-affected zone (HAZ) of high nitrogen stainless steel containing about 1% nitrogen, and decreases the critical pitting corrosion temperature. Recently, Zhang et al [5] studied the effect of brazing temperature on the microstructure and mechanical properties of HNASS joints brazed with Ni–Cr–P filler and also found Cr 2 N compounds at the HNASS/filler interface when the temperature was below 1000 °C. The solidification cracking due to nitrogen addition was also found by Woo and Kikuchi [6].…”