Strain hardening and plastic instability properties of austenitic stainless steels after proton and neutron irradiation

Strain hardening and plastic instability properties were analyzed for EC316 LN, HTUPS316, and AL6XN austenitic stainless steels after combined 800 MeV proton and spallation neutron irradiation to doses up to 10.7 dpa. The stee ls retained good strain-hardening rates after irradiation, which resulted i n significant uniform strains. It was found that the instability stress, th e stress at the onset of necking, had little dependence on the irradiation dose. Tensile fracture stress and strain were calculated from the stress-st rain curve data and were used to estimate fracture toughness using an exist ing model. The doses to plastic instability and fracture, the accumulated d oses at which the yield stress reaches instability stress or fracture stres s, were predicted by extrapolation of the yield stress, instability stress, and fracture stress to higher dose. The EC316LN alloy required the highest doses for plastic instability and fracture. Plastic deformation mechanisms are discussed in relation to the strain-hardening properties of the austen itic stainless steels. (C) 2001 Elsevier Science B.V. All rights reserved.