Low-cycle fatigue behaviour of a low-alloy high-strength steel

Abstract

The low-cycle fatigue behaviour of a high-strength CrMoV steel has been evaluated in the as-received (AR) and the quenched and tempered (QT) conditions, at room temperature. While the quenching and tempering treatment causes a marked increase in the tensile strength and hardness, it leads to an impairment of the fracture toughness and the low-cycle fatigue (LCF) resistance of the material. A fractographic examination reveals that while there is a large zone of fatigue crack propagation the AR condition, in sharp contrast there is small zone of fatigue crack propagation and a large zone of static fracture in the QT condition. The reduction in fatigue resistance of the QT material is attributed to a loss in fracture toughness and a fall in the values of ϵ_f′ and n′.