Effect of neutron irradiation on fracture behaviors of A 516 Gr.70 steel and Armco iron in the dynamic strain aging regime

The fracture behaviors of A516 Gr.70 steel for reactor support and Armco iron were investigated with special emphasis on the synergistic effects of interstitial impurities and radiation-induced defects in the dynamic strain aging (DSA) regime. The steel clearly depicted decreased fracture resistance in the upper shelf region where DSA is noted. In contrast, Armco iron showed improvement in fracture initiation energy during DSA. These contrasting behaviors are believed to arise from the existence or lack of precipitates for crack nucleation sites. The superimposed radiation effects revealed complex trends, while test results on the steel clearly demonstrated the suppression of DSA, resulting in apparent improvement in the ductility and fracture energy, due to the interaction of interstitials with radiation-induced defects