Effects of Carbide Size on Fatigue Properties of P/M High-Speed Steel

Several P/M (Powder Metallurgy) high-speed steels with different sizes of carbide particles, which is one of the predominant factors influencing wear properties, strength etc., were prepared. In the plain fatigue tests, the plain fatigue strength of the specimen with large carbide particles was lower than that with small carbide particles. This result is obtained because fatigue cracks are initiated at carbide particles. In fretting fatigue tests, the fretting fatigue strength decreased with increasing carbide particle size. This is mainly because the frictional coefficient of the materials decreased with decreasing carbide particle size. According to the results of the fatigue crack growth tests, the carbide particle has no significant influence on the fatigue crack growth rate. The predicted lives based on the fracture mechandcs model of fretting fatigue were in good agreement with the experimental results.