Creep Crack Growth Modelling in 316H Stainless Steel

Abstract

It has been realised that plasticity has a significant effect on the creep ductility of Austenitic Type 316H stainless steel at $$550\,^\circ \mathrm{{C}}$$ . Recently a model has been produced to estimate the creep ductility and strain rate as a function of the plastic strain levels in the material. A variable creep ductility model, incorporating stress dependent strain rate effects, has therefore been implemented in a finite element (FE) analysis to predict creep crack growth (CCG) in 316H stainless steel at $$550\,^\circ \mathrm{{C}}$$ . Recent experimental results have shown that material pre-compression to 8 % plastic strain at room temperature accelerates the creeping rate and significantly reduces the creep ductility of 316H stainless steel at $$550\,^\circ \mathrm{{C}}$$ . In addition pre-compression significantly hardens the material and thus the levels of plasticity on specimen loading in tension are reduced. As a result, accelerated cracking rates are observed in pre-compressed (PC) materials compared to as-received (AR) (non-compressed) materials. The variable creep ductility FE CCG model has been employed to predict the CCG behaviour of AR and PC materials and to analyse their differences. Comparisons are also made to FE and analytical constant creep ductility models.