Cyclic deformation behavior and microstructural changes of 12Cr–WMoV martensitic stainless steel at elevated temperature

Strain-controlled uniaxial push–pull low-cycle fatigue tests were performed on 12Cr–WMoV martensitic stainless steel at room temperature and 600 °C. Specimens were tested at total strain amplitudes of 1.5% and 0.8% with a constant strain rate of 0.004 s−1. The microstructures of the specimens subjected to different cycles were studied using transmission electron microscopy (TEM). Cyclic softening was observed at room temperature and 600 °C. TEM investigations revealed that cellular structures of dislocations were formed in the fatigued specimens at both room and elevated temperatures. Dynamic recovery has a very significant effect on the dislocation structure of specimens tested at elevated temperature. The thickness and density of the dislocation cell walls formed in specimens cycled at 600 °C are less than that at room temperature. Cellular dislocation structures formed during cycling are annihilated in the specimens subjected to 1 h annealing at 600 °C.