Environmental Effect on Fatigue Crack Initiation under Equi-Biaxial Loading of an Austenitic Stainless Steel

Abstract

The lifetime extension of nuclear power stations is considered an energy challenge worldwide. That is why the risk analysis and the study of various effects of different factors that could potentially prevent safe long-term operation are necessary. These structures, often of great dimensions, are subjected during their life to complex loading combining varying multiaxial mechanical loads with non-zero mean values associated with temperature fluctuations under a PWR (pressure water reactor) environment. Based on more recent fatigue data (including tests at 300 °C in air and a PWR environment, etc.), some international codes (RCC-M, ASME, and others) have proposed and suggested a modification of the austenitic stainless steels fatigue curve combined with a calculation of an environmental penalty factor, namely Fen, which has to be multiplied by the usual fatigue usage factor. The determination of the field of validation of the application of this penalty factor requires obtaining experimental data. The aim of this paper is to present a new device, “FABIME2e” developed in the LISN (Laboratory of Integrity of Structures and Normalization) in collaboration with EDF (Electricity of France) and Framatome. These new tests allow the effect of a PWR environment on a disk specimen to be quantified. This new device combines structural effects such as equibiaxiality and mean strain and the environmental penalty effect with the use of a PWR environment during fatigue tests.

Characterization of Austenitic Stainless Steels with Regard to Environmentally Assisted Fatigue in Simulated Light Water Reactor Conditions

“…Besides these tests on uni-axial specimens, the project included also a sub-programme on membrane specimens. The results of this sub-programme were published separately [28].…”

Environmental Fatigue Assessment of Metallic Materials and Components

“…Eight research contributions have been published in this Special Issue. Six contributions [1][2][3][4][5][6] are directly derived from the INCEFA-PLUS project, whereas two [7,8] are external contributions.…”

“…While Simonovski et al [4] present a technical paper on the calibration of strain measurements on the shoulder of uniaxial specimens in autoclaves, Gourdin et al [5] introduce an innovative device for experimental investigations of environmental fatigue under biaxial conditions.…”