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

• Published in: International journal of fatigue 2021-07, Vol.148, p.106254, Article 106254
• Main Authors: Cheng, L., Yu, W., Cai, Q.W., Yang, Q.
• Format: Article
• Language: English
• Subjects: Anisotropy; Austenite; Boundary layer transition; Cooperative control; Deformation mechanisms; Fatigue life; Grain boundaries; Grain boundary sliding; Grain size; Heat resistant steel; Heat resistant steels; Heat treating; High-temperature fatigue; Materials fatigue; Metal fatigue; Prior austenite grain boundary; Strain rate; Thermal fatigue; Viscoelasticity
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2021.106254

•The quasi in-situ approach realized the study of particular grain boundaries.•Effects of PAGBs on deformation mechanism was clarified both at 550 °C and 650 °C.•Fatigue life was discussed by considering the viscoelasticity of PAGBs. 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.