Deformation and Fracture Behavior of AISI 403 Stainless Steel for Nuclear Structural Applications

摘要

The deformation and fracture behavior of AISI 403, a tempered martensitic stainless steel for end fitting component application of Pressurized heavy water reactor is being reported. The deformation behavior studies entailed characterization of tensile behaviour in the temperature range 77K - 873K for the as received and the fine grained Nb modified variant of AISI 403. The study of elevated tensile behavior in the two steels has been undertaken with the purpose of characterizing the strain rate - temperature domain of the occurrence of dynamic strain aging (DSA) phenomenon. In both steels, while the temperature range for the manifestations of characteristic anomalies in the tensile curve due to DSA was observed within 523K - 673K, the strain rate domain for the fine grain Nb variety was significantly higher as compared with the as-received variety. The low temperature tensile tests for the as received AISI 403 revealed the presence of pseudo-alloy softening temperature range 273-193 K. The effect of high DBTT of the AISI 403 steel was shown by the fracture toughness tests in the J-integral format at room temperature that displayed significant scatter in the samples with high in-plane and out-of-plane constraint. Samples with lower constraint showing stable crack growth were further tested at high temperature to obtain the temperature dependence of initiation toughness and propagation toughness. Within the DSA temperature a sharp decline in the fracture properties was observed. A mechanistic interpretation for the manifestations of the various observed phenomena is presented.