A comprising steady-state creep model for the austenitic AISI 316 L(N) steel

Low-stress creep data of a recently finished special long-term program now allows for much better long-term predictions of the ITER related material 316 L(N) and also enables deformation modeling for a broader stress range. The present work focuses mainly on the set-up of a steady-state creep model with help of well-known rate-equations for different deformation mechanisms. In addition, the impact of microstructure changes and precipitation formation on steady-state creep is studied. The resulting creep model consists of a summation of contributions for diffusion creep, power-law creep, and power-law breakdown. The final creep model agrees well with experimental data for temperatures between 550 and 750 °C and for shear stresses above 30 MPa. The most important finding of this work is that for very low stresses the model predicts far higher creep rates than can be extrapolated from tests performed at the usual stress range of experimental programs.