The microstructure, mechanical properties and fracture behavior of hastelloy C276-BNi2 brazed joint

Abstract

In this study, the microstructure, mechanical properties and fracture behavior of hastelloy C276-BNi2 brazed joint were investigated. The results show that microstructure and mechanical properties of the joints are greatly affected by the test temperature and inner brazing defects. The brazed joint consists of four regions, i.e. filler zone, fine grain diffusion zone, coarse grain diffusion zone and parent zone. Because of element diffusion in brazing, the diffusion zone becomes harder and the filler zone becomes softer. Compared with base metal, both the yield strength and elongation of brazed joint are relatively small. The filler metal plays a key role in determining the mechanical properties of brazed joint. The specimen fractured in the filler zone with ductile mode by stepped pattern. Because of the existence of brazing defects between grain boundaries, the fracture was accelerated, both the yield strength and ultimate tensile strength of defect-containing joint were decreased compared to the defect-free joint.