Study on Microstructure Transformation and Properties of High Speed Steel Sintered by M2/Ti Powders

The mixed powders of Ti and M2 were prepared by using mechanical alloying method, which was molded and then sintered under vacuum circumstance, then the sintered alloy containing Ti was obtained. The densification behavior,microstructure and mechanical properties of the sintered samples were studied. The results show that the mixed powder of M2 and Ti after wet grinding is pebble-like with a medium particle size of 15.5 μm, and Ti element is evenly distributed in the powder matrix. When it is sintered at 900-1030 ℃, the sintered samples have low density, and a large number of fine M₆C carbides are uniformly distributed in the matrix, and the carbide size is small. With the increase of the sintering temperature,the density of the sample increases, the porosity decreases, the original carbides in the sample grow, and more fine carbides precipitate. When it is sintered at 1110-1150 ℃, the structure homogenization decreases, the M₆C carbides grow to irregular and the content of MC carbides increases. The increase of sintering temperature make the carbides grow obviously, and the carbides are agglomerated, black carbide particles and MC carbides are densely formed around the M₆C carbides. Apparent hardness of the sample increases with the increase of sintering temperature. The material sintered at 1150 ℃ has the highest hardness of 55.2 HRC. The bending strength rises first and then falls, and the material sintered at 1140 ℃ has the maximum bending strength of 1556 MPa.