Determination of multiaxial creep stress rupture criteria for 316H stainless steel at 600 °C

In this work, the applicability of three different methods, denoted as the direct method, the indirect method, and the simple empirical method based on uniaxial creep damage tolerance parameter, λ, for the determination of multiaxial stress rupture criterion (MSRC) is assessed. The assessment involves four commonly-used MSRCs, the Sdobyrev and Hayhurst-Leckie (denoted as SHL), the Cane, the Nix and the Huddleston MSRCs. To this end, creep tests on both uniaxial and circumferentially-notched tension (CNT) specimens of 316H stainless steel are carried out at three net-section stress levels, that is, 300 MPa, 320 MPa and 340 MPa, and at 600 °C. The results show that all the three methods are suitable for the determination of MSRC for the steel examined. Of these, the direct method data-based simple empirical equation is attractive as it takes good advantage of uniaxial creep data in terms of reflecting the operative creep failure mechanism, and therefore may serve as an alternative for the determination of the SHL MSRC, particularly when multiaxial test data is not available. Moreover, the determined SHL, Cane and Huddleston MSRCs are found to be equally effective in the creep life prediction of both uniaxial and CNT specimens, while the effectiveness of the Nix MSRC in life prediction depends on position for stress output and material. In addition, factors influencing the determination of MSRC for stainless steels are discussed in terms of experimental data available in the literature.