Creep and creep-rupture properties of type 1.4970 stainless steel during and after irradiation

Publisher Website
Google Scholar
Abstract
The purpose of this paper is to report some observations on the basic damage processes controlling the rupture-life properties of unirradiated, irradiated, and in-reactor creep tested samples. In the first part the influence of different pre-treatments on the microstructure of 1.4970 steel after BR2 irradiation is analyzed. The effective concentration of helium near the grain boundaries is governed by the boron-bearing grain boundary precipitates. The distribution of helium bubbles within the grains is mainly influenced by dislocations rather than by secondary TiC precipitates and their interfaces. In post-irradiation creep tests, specimens showed that a considerable reduction in ductility occurs for all states of the material. In contrast to the ductility losses, the creep-rupture strengths are almost unaffected by the pre-irradiation states of the material. In the second part the published results on the in-pile creep-rupture properties of the same material are given. They indicate a marked reduction in the creep-rupture life due to irradiation. It is proposed that the in-pile creep rupture-life behaviour is caused by the SIPA creep, which operates below a specific stress level.