THE TENSILE AND FATIGUE PROPERTIES OF DIN 1.4914 MARTENSITIC STAINLESS-STEEL AFTER 590 MEV PROTON IRRADIATION

Tensile and low cycle fatigue subsize specimens of DIN 1.4914 martensitic steel (MANET) have been irradiated with 590 MeV protons to doses up to 1 dpa and at temperatures between 363 and 703 K. The helium produced by spallation reactions was measured as 130 appm/dpa. A strong radiation hardening is found, which decreases as the irradiation temperature increases. The tensile elongation is reduced after irradiation, but the fracture mode is always ductile and transgranular. The radiation hardening produced at low irradiation temperatures is recovered after annealing at higher temperatures. Continuous softening is observed during low cycle fatigue testing. The rate of softening of the irradiated material is stronger than that of the unirradiated material and tends to reach the saturation level of the latter. The irradiation badly affects the fatigue life, particularly in the temperature domain of dynamic strain ageing between 553 and 653 K.