Effect of microstructural evolution on the cyclic softening of a 10% Cr martensitic steel under low cycle fatigue at 600 °C

Microstructure evolution and softening during interrupted low cycle fatigue (LCF) tests at 600 degrees C and constant strain amplitudes of +/- 0.2% and +/- 0.6% corresponding to dominance of the elastic and plastic strain components, respectively, was examined in a 10% Cr steel. Cyclic softening attributed to changes in the strengthening from dislocations and lath structure is more pronounced during the first half-life. The Burgers vector analysis of dislocation reveals the role of the single and multiple dislocation slip in retention and transformation of lath structure at cycling with low and high strain amplitude, respectively.