Research Of Microstructure And Wear Properties Of M3/2 Powder Meatallurgy Highspeed Steels Reinfored By TiC Particles

M3/2 powder metallurgy high-speed steels containing different volume fractions of TiC particles (M3/2-TiC for simplicity) was fabricated by cold-pressing sintering. The friction and wear behavior of the M3/2-TiC were investigated. The volume fractions of TiC particles were 2vol.%, 4vol.%, 6vol.%, 8vol.% and 10vol.%; and the sintering temperatures were 1240°C, 1260°C, 1280°C and 1300°C, respectively. Sinter density, hardness, friction factor and wear properties of the M3/2-TiC were tested. The phases, microstructure, friction and wear mechanism were studied by X-ray diffraction technique (XRD), scanning electron microscope (SEM) and X-ray energy dispersive spectrometer (EDS).The results show that the sinter density of the M3/2 powder metallurgy high-speed steels containing TiC particles is increased with the increase of sinter temperature. There is an optimal value at the temperature of 1300°C. The hardness of M3/2-TiC shows the similar behavior, increasing with the sinter temperature at the same volume fractions of TiC particles. At the sintering temperature of 1300°C, the hardness of M3/2-TiC is found to increase initially with increasing the volume fractions of TiC particles. As the volume fractions of TiC particles is 6vol.% in the M3/2 powder metallurgy high-speed steel, the hardness reaches a maximum value. Reversely, more addition of volume fractions of TiC particles than 6 vol.%, causes decreasing of the hardness of M3/2-TiC.The homogeneous of microstructures of M3/2-TiC is improved by low volume fractions of TiC particles. The network-like M6C-type carbonates in M3/2 vanish. Lumpish-like M6C type carbonates were formed and distributed homogenous in the alloy matrixes. The TiC particles are tended to aggregate and lots of holes appear near the aggregates when the volume fraction of TiC particles is more than 6vol.%, which affect severely the homogenous of the microstructures, leading to the decrease of mechanical properties.The results of the friction and wear measurements of the M3/2-TiC show that the weight loss of M3/2-TiC decreases initially with the increase of volume fraction of TiC particles. The weight loss of M3/2-TiC reaches its minimum value of 4.21 mg when the volume fractions of TiC particles is increased to 6vol.% in the M3/2 powder metallurgy high-speed steel. The weight loss of M3/2-TiC begins to increase with further increasing the volume fractions of TiC particles. These are because of two factors. One is the good wearability of TiC particles and the other is reinforced wearability of matrixes by low volume fraction of TiC particles because of approved cohesion between matrixes and TiC particles. The analysis of microstructure of M3/2-TiC before and after wear show that the main mechanism is adhensive wear and oxidative wear.In conclusion, M3/2-TiC with homogeneous microstructure were obtained with 6vol.% volume fractions of TiC particles. This material shows good wear resistance and has the potential worth for further investigated.