Isochronous creep rupture loci on deviatoric plane and its application to P92 steel creep behaviour under multiaxial stress state

The transformation relationship of the coordinate variables between principal stress space and deviatoric stress plane has been deduced and the isochronous creep rupture loci of disparate criteria have been described on deviatoric stress plane so as to analyze the creep behaviour under multiaxial stress state. The creep experiments of P92 steel smooth and notched specimens subjected to various stresses at 650 °C have been conducted. A modified constitutive model for the creep of P92 steel has been proposed and used to simulate the creep of P92 steel notched specimens with FEA software. The FEA results were consistent with the experimental data and the fracture morphology observation. It was found that the Hayhurst criterion had the best correlation with the experimental results of P92 steel under multiaxial stress state than other criteria through the comparison of the isochronous creep rupture loci on deviatoric plane.