Prediction of Creep Damage in 316H Stainless Steel

A creep crack growth (CCG) model has been developed, for 316H stainless steel, an ASME-certified material for applications in high temperature nuclear reactors. A progressive damage model has been employed in conjunction with the Cocks-Ashby ductility exhaustion approach, using a range of creep failure ductilities, to simulate creep damage and hence predict the progression of creep damage and crack growth in 2D and 3D side-grooved compact tension, C(T), specimen and a thin plane-sided single edge notch tension, SEN(T) geometry. The damage model was implemented in the commercial code ABAQUS via a user-defined field (USDFLD) subroutine. Damage and crack initiation time were extracted to produce predictive CCG plots, showing crack growth progression as a function of time. The results were then validated by comparing the predicted crack growth to experimental CCG data. In the plane stress models, cracks propagated perpendicular to the load as expected. In plane strain, cracks deviated from their original crack plane to an approximate 45° angle before proceeding to turn horizontal with the C(T) specimens but remained at 45° with the SEN(T) specimens. The 3D mesh was required to provide a good prediction of the standard sized C(T) test data however a 2D plane stress simulation was sufficient to provide a reasonable prediction for the thin SEN(T) test data.