Radiation effect on oxide-dispersion-strengthened ferritic/martensitic steel under influence of applied stress and improvement of shape stability under irradiation

Sakasegawa, Hideo   

9Cr-ODS (Oxide Dispersion Strengthened) steels developed by JAEA have superior creep properties. The 9Cr ODS steel displaying an excellent creep property is a dual phase steel. The ODS steel is strengthened by the delta ferrite which has a finer dispersion of oxide particles and shows a higher hardness than the martensite. Its creep behavior is very unique and cannot be interpreted by conventional theories of heat resistant steels. Alternative model of creep mechanism was studied using the results of microstructural observations. Based on the alternative creep mechanism model, a novel creep constitutive equation was formulated. In addition to that, modifications of material processing procedures for improving the creep property under irradiation and unirradiation were performed considering procedures for mass production.