Study on microstructure and mechanical property of Ti-6Al-4V brazed joint with low temperature filler metal

Abstract

This study investigates the microstructure and mechanical properties of Ti-6Al-4V brazed joints which has been performed in a vacuum furnace using BAg-22 (Ag–16Cu–23Zn–4.5Ni-7.5Mn, wt. %) as filler metal. The microstructure of the brazed joints has been analyzed by means of optical microscope, scanning electron microscope (SEM) and X-Ray diffraction (XRD). In addition, the mechanical strengths of the joints have been evaluated by shear test and microhardness test. Brazing temperatures employed in this study are 720, 750, and 780 °C for a holding time of 30 min. By increasing the brazing temperature, a variety of intermetallic phases have been formed in the bond area, such as CuTi, CuTi₂, Mn₂Ti, MnZn₂, AgZn and Ag solid solution. Both the brazing temperature and the brazing time seem have critical factors for controlling the microstructure and the better mechanical property of the brazed joints. The maximum shear strength of 154.15 MPa has been achieved at 780 °C and a holding time of 30 min.