Creep rupture behavior of Grade 91 steel

Grade 91 steel is considered a potential structural material for advanced nuclear reactors. The creep deformation behavior of Grade 91 steel was studied in the temperature range of 600–700 °C and at stresses of 35–350 MPa. The data were analyzed in terms of Monkman-Grant relation and Larson–Miller parameter. Creep damage tolerance factor and stress exponent were used to identify the cause of creep damage. The fracture surface morphology of the ruptured specimens was studied by scanning electron microscopy to elucidate the failure mechanisms. Fracture mechanism map for Grade 91 steel was developed based on the available material parameters and experimental observations.