The analysis of strain response for as-received and exploited 10H2M power engineering steel subjected to low cycle fatigue in plastic regime

Thermal shocks occurred during power plant station shutdowns result in notable changes in material microstructure and affect its mechanical behaviour significantly. High temperature gradients as well as internal pressure changes in pipes are also responsible for external and internal stress introduction. Such stress may also exceed the yield strength of the material resulting in its deformation. Thus, in this work, the comparative studies on 10H2M power engineering steel in the as-received and exploited state (280 000h at 540 degrees C under internal pressure of 1.8 MPa) subjected to low cycle fatigue in the plastic regime were performed. The strain response of both states of steel was monitored for three different values of stress amplitude exceeding the yield strength of the material. The significant differences in strain response were found for both states of steel when subjected to the same stress amplitude.