A method to quantify thermal aging effects on fracture toughness of cast stainless steels (CSSs)

摘要

This paper proposes a methodology to quantify the effects of thermal aging on fracture toughness of cast stainless steels (CSSs) using small punch (SP) tests and finite element (FE) damage analyses. SP tests and C(T) tests are conducted using virgin (unaged) and thermally aged (up to 5,000 hours at 400°C) CF8M that is a type of cast stainless steels. The FE damage simulation method used in this paper is based on the multi-axial fracture strain model. The multi-axial fracture strain models are determined from SP tests data and FE analysis results. C(T) tests are simulated using these multi-axial fracture strain models. To validate the methodology in this paper, C(T) simulation results are compared with test data. The initiation toughness values from C(T) simulation results are predicted well and the simulated fracture toughness values are slightly conservative compared to test data. The methodology in this paper may be used for assessing instability of operating power plant and other aged structural components.