Radiation Effects on Low-Cycle Fatigue and Tensile Properties of AISI Type 304 Stainless Steel at 298 K

摘要

Mechanisms were studied on the effect of neutron damage on low-cycle fatigue and tensile properties at room temperature on stainless steel AISI type 304. Samples were irradiated in the HFR at Petten to a fast fluence of 5.10 exp 24 n.m exp -2 (E > 0.1 MeV) at 333 K followed by mechanical testing at room temperature. The low temperature irradiation caused irradiation hardening: the 0.2 yield stress increased from a value of 230 MN.m exp -2 for the unirradiated material to a lower yield point value of 540 MN.m exp -2 . Irradiation had no significant effect on fatigue life. The loop type damage was removed by glide dislocations resulting in cyclic softening. Dislocation substructures were observed after fatigue testing: cell structures were more pronounced to failure after fatigue testing, the higher the applied strain ranges. The formation of fatigue cracks at the surface of the specimens was observed in a series of specimens exposed to an increasing number of fatigue cycles. The tensile properties after fatigue loading and measured at the strain rate epsilon of 1 s exp -1 were found to be closely related to prior cyclic softening or hardening and to the development of large fatigue cracks. (Atomindex citation 09:375959)