The Dependence of Fracture Mode On Interfacial Microstructure in Ta1 Pure Titanium/Agcuni/304 Stainless Steel Vacuum Brazed Joints

Vacuum brazing of TA1/304 stainless steel (SS) was systematically investigated by adjusting the composition of the filler metal, brazing temperature and holding time. The addition of nickel to the filler metal avoided excessive TixCuy phases on the 304 SS substrate side and eliminated the TiFe phase. The defect-free joint with the shear strength of 148 MPa was obtained by using the filler metal of AgCuNi, the brazing temperature of 880 °C and the holding time of 10 min. The holding time affected the distribution of Ti3Cu4 phase near the TA1 side and the brazing temperature affected the distribution of TiCu4 and TiFe phases near the 304 SS side, which caused cracking from the interface between the weld and the substrate. The excessive TiCu4 and TiFe phases near the 304 SS side led to the transition of the shear section from the entire weld to the interface between the weld and the substrate