Discussion on Microstructure and Mechanical Properties of Alumina Ceramic and Cr12 Steel Active Brazed Joints

Using self-developed Cu-Sn-Ti-Ni active filler powder, a series of the brazing tests were carried on Al2O3 ceramics and Cr12 steel at 870-930 ℃ for 5-20 min. The microstructure of the joints brazed was evaluated by SEM and EDS.The results show that it has a good wetting and metallurgical bonding between filler and the both side of the base metal. In brazing process, Fe element of the base of steel diffuses into filler layer; Ti element of filler diffuses into the both side of the base metal and forming Ti Fe2 and Ti C compounds in filler layer side of steel base metal. The maximum shear strength of the welded joints was 118 MPa, which is achieved when the brazing temperature is 890 ℃ and holding time is 10 min.