Effect of calcium on the microstructure and mechanical properties of brazed joint using Ag–Cu–Zn brazing filler metal

The induction brazing of 316LN stainless steel using Ag–Cu–Zn filler metal containing various content of Ca was carried out to investigate the influence of impurity element Ca on the microstructure and mechanical properties of the brazed joint. The results showed that Ca additions caused the coarser of the grains and their irregular distribution. Increase of the Ca content resulted in the formations of brittle intermetallic compounds (IMCs) CaCu which perhaps lead to the formations of voids. All of the calcium-containing brazed joints performed better in microhardness than calcium-free ones and brazed joints containing 0.003 wt.% Ca showed the highest microhardness of 203HV. While the tensile strength decreased with the increment of Ca, from 460 MPa to 400 MPa. The combination effects of coarser grains, brittle IMCs and voids conduced to the reduction of tensile strength and microhardness of the brazed joints.

► Effect of Ca on brazed joint using Ag–Cu–Zn brazing filler metal was investigated. ► 0.1 wt.% Ca resulted in the formation of brittle CaCu, which caused voids. ► Ca addition led to coarser and irregular distribution of phases in the matrix. ► Tensile strength decreased with the increment of Ca. ► Ca-containing brazed joints had higher microhardness than the Ca-free ones.