Assessment of the defect stability for large structures submitted to thermal shock loading through the Gfr criterion

Abstract

This paper proposes a formulation and a numerical protocol to allow the application of the Gfr criterion for thick stainless steel components submitted to thermal shock loading. In a first part of the paper, a short description of the criterion initially defined in the S. Marie's PhD is proposed. The proposition to extend the criterion to thermal loading is then made based on the elastic-plastic stresses determined on the crack free model and the classical influence function formulation.Following this description and proposition of extension, two numerical applications are proposed in order to illustrate the applicability of the modified protocol and its coherence with already existing schemes.In a third part, a validation through the comparison to a large scale test performed on CF8M cast stainless steel material is made. This test was chosen since the Gfr criterion is a candidate for defect stability evaluation in cast components. It is then shown that the parameter can be determined on standard specimen, then used to predict the ductile crack growth in large component made of complex materials such the duplex cast stainless steel.