Effects of prior austenite grain boundaries on high-temperature fatigue properties of a 2.2Cr heat resistant steel

摘要

High-temperature fatigue mechanism of two 2.2Cr heat resistant steels that featured different prior austenite grain size were studied by using a strain-stress cooperative control strategy. Softening of grain boundaries led to a transition of deformation mechanism, during which the reaction of subboundaries within grains was replaced by the sliding of prior austenite grain boundaries (PAGBs) as the temperature increased from 550 °C to 650 °C. Moreover, increase of strain rate at 650 °C brought opposite effects on peak stress and fatigue life for the two matrixes, which was caused by the microscopic deformation anisotropy that induced by the viscoelasticity of PAGBs.