Low cycle fatigue properties of CLAM steel at room temperature

•The LCF properties of the CLAM steel follow the Coffin–Manson relationship.•The fatigue life can be expressed as a function of the total strain amplitude.•Initial hardening during first number of cycles followed by softening to failure.•Initial state CLAM steel has small grains which consist of thin martensitic laths.•Morphology of fatigue surface continues changing when the strain amplitude increases.

The low cycle fatigue (LCF) properties and the fracture behavior of China Low Activation Martensitic (CLAM) steel have been studied over a range of total strain amplitudes from 0.2 to 2.0%. The specimens were cycled using tension-compression loading under total strain amplitude control. The CLAM steel displayed initial hardening followed by continuous softening to failure at room temperature in air. The relationship between strain and fatigue life was predicted using the parameters obtained from fatigue test. The factors effecting on low cycle fatigue of CLAM steel consisted of initial state of matrix dislocation arrangement, magnitude of cyclic stress, magnitude of total strain amplitude and microstructure. The potential mechanisms controlling the stress response, cyclic strain resistance and low cycle fatigue life have been evaluated.