Microstructure and corrosion resistance of TLPB of Inconel 625 to 316l SS

Abstract

In this paper, the microstructure and electrochemical behaviour of a transient liquid phase (TLP) bonding between Inconel 625 and 316L stainless steel with a Cu interlayer were investigated. The TLP bonding was performed at 1090°C and 1120°C for 30 and 60 min. For microstructural analysis, FESEM and TEM were used. To analyse the corrosion resistance, EIS and Potentiodynamic polarisation tests in 3.5% NaCl were performed on the joint. Microstructural analysis suggested the presence of Mo–Nb, Cr–Mo and Nb-rich precipitations in the diffusion affected zone (DAZ) in the Inconel 625 side and Mo–Nb and Mo-rich precipitates in the Cu interlayer. The EIS and potentiodynamic polarisation tests showed that the highest corrosion resistance was achieved for the 1120°C-30 min sample.