Postirradiation Creep and Stress Rupture of Hastelloy N

The creep ductilities of irradiated Hastelloy N at 650°C have been determined at several neutron exposures. Elevated-temperature irradiation embrittlement greatly reduces the stress-rupture strength as measured in postirradiation uniaxial stress tests. The reduction in ductility to values as low as 0.4% is due to an irradiation effect related to the process of intergranular fracture. Intergranular cracks, once formed, propagate with greater ease in the irradiated alloy as compared with a sample exposed to a lesser radiation exposure.