Crack growth evaluation of a multimaterial CS-type specimen

Abstract

During the German HDR Safety Program the integrity of a reactor pressure vessel was studied intensively during a pressurized thermal shock loading. As a part of the work this paper presents a stable crack growth evaluation for a side-grooved, multimaterial CS-type specimen, which was detached from the inner surface of the HDR reactor pressure vessel. The specimen was composed of ferritic base material and two austenitic cladding material layers. The specimen was tested at the Fraunhofer-Institut für Werkstoffmechanik, Freiburg, Germany, and revealed an extremely nonuniform stable crack growth distribution along the crack front. Elastic-plastic finite element analyses were carried out using the 85-version of the ADINA code. For crack growth simulation a separate subroutine package IWM-CRACK linked with ADINA was used. Additional J-integral calculations were carried out based on the ADINA results, using the VTTVIRT code in order to study the path dependence of the J-integral. The crack growth was controlled by J r curves, while actual measured data were available only for the base material, and hypothetical J r curves were applied for the two cladding layers. The calculated maximum load was slightly higher than the maximum load measured in the test. The crack growth was relatively well simulated in quality. The slight numerical discrepancies at some locations along the crack front were consistent with extreme local material brittleness, which was clearly underestimated by the assumed material properties.