Microstructure and shear strength of the brazed joint of Ti(C,N)-based cermet to steel

Abstract

Firm joins were obtained between Ti(C,N)-based cermet and steel with Ag-Cu-Zn-Ni filler metal by vacuum brazing. The effects of technological parameters such as brazing temperature, holding time, and filler thickness on the shear strength of the joints were investigated. The microstructure of welded area and the reaction products of the filler metal were examined by scanning electron microscopy (SEM), metallographic microscope (OM), energy-dispersive X-ray analysis (EDS), and X-ray diffraction (XRD). The brazing temperature of 870°C, holding time of 15 min, and filler thickness of 0.4 mm are a set of optimum technological parameters, under which the maximum shear strength of the joints, 176.5 MPa, is achieved. The results of microstructure show that the wettability of the filler metal on Ti(C,N)-based cermet and steel is well. A mutual solution layer and a diffusion layer exist between the welding base materials and the filler metal.

Interface structure and mechanical properties of Ti(C,N)-based cermet and 17-4PH stainless steel joint brazed with nickel-base filler metal BNi-2

“…5 shows the shear strength of the brazed joints under various brazing temperatures. The joint shear strength increased with increasing the brazing temperatures from 1050 to 1150 • C, and reached a maximum value of 690 MPa at 1150 • C, which was much higher than that obtained using Ag-based filler metal (176 MPa) (Ye et al, 2010). The variation of the joint strength with the brazing temperature was well correlated with the microstructural evolution of the joints, especially the distribution of the MPD and the brittle phases generated in the brazing seam.…”