Mechanistic Studies of Fatigue in Austenitic Stainless Steels in a Pressurised Water Reactor Primary Coolant

Abstract

Austenitic stainless steels are widely used in the internals of pressurised water reactors (PWRs) due to their good mechanical properties and corrosion resistance. However, when exposed to a simulated PWR environment they can exhibit a significant enhancement of fatigue crack growth rates (FCGRs) compared to specimens tested in air. This study is separated into two parts; with the first part focused on the analysis of specimens subjected to more plant realistic waveforms. Comparisons of different methods to evaluate crack growth rates (CGRs) highlighted a 1:1 relationship between striation spacing and CGRs, which gives confidence in this method to be used on specimens where in-situ crack monitoring is not practical. The second part of the work was focused on the effect of temperature on fatigue in a simulated PWR environment, with a particular focus on temperatures less than 150 °C. The crack growth results highlighted a difference in fatigue behaviour above and below 150 °C, with an ‘upturn’ in the CGR below 150 °C. Microstructural analysis showed that α’-martensite formed in crack growth stages conducted at low temperatures (T

Date of Award	9 Aug 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Fabio Scenini (Supervisor), Joao Quinta Da Fonseca (Supervisor) & Grace Burke (Supervisor)