EMPIRICAL EQUATIONS FOR TENSILE PROPERTIES AND STRESS-STRAIN CURVES OF NEUTRON IRRADIATED STAINLESS STEELS IN LWR CONDITIONS

摘要

For structural integrity assessment on reactorinternals of light water reactors (LWRs), new empiricaltrend curves for tensile properties (yield strength,ultimate tensile strength, uniform elongation and totalelongation) and stress-strain relations of neutronirradiatedaustenitic stainless steels have been proposedby fitting to recently developed database. The data in thedatabase were obtained from reports of national projectsin Japan and open literature, which have beensummarized in the form of data sheets. Model equationsfor tensile properties were formulated by using asaturation-type equation, A+B[1-exp(dpa/C)]. Theequations are for cold-worked 316 and solution-annealed304/316 stainless steels in the temperature range of 280-350ºC and the dose range up to 80 dpa. The stress-straincurves were formulated by using the Swift model, σ =k(a+ε)n, where a, k and n are constants. The value of 0.5was used for n, and a and k were expressed by yieldstrength and/or tensile strength, which can be obtainedfrom tensile testing or the proposed trend curves. Theobtained stress-strain curves were reasonably well fittedto experimental curves. The effects of material varietiessuch as composition and cold-working were discussed.