Fatigue crack growth behavior of hybrid and prealloyed sintered steels

Powder metallurgy (P/M) steels will encounter fatigue loading in service. A fundamental understanding of porosity and steel matrix microstructure on fatigue behavior is important. In this paper, the fatigue crack growth behavior of hybrid and prealloy Ni-Mo P/M steels was investigated. The density of P/M steels was varied from 7.0 to 7.6 g/cm3. The relationship between microstructure and fatigue crack growth was investigated in detail. The density, matrix microstructure, and the degree of pore clustering had a significant effect on the crack growth behavior. The crack closure and two parameters (static: Kmax and cyclic: ΔK) were employed to describe and explain the fatigue behavior of the steels.