Synergistic effects of interstitial impurities and radiation defects on mechanical characteristics of ferritic steels

Ferritic steels are generally used in pressure vessels and various reactor support structures in light water reactors. They are known to exhibit radiation embrittlement in terms of decreased toughness and increased ductile–brittle transition temperature as a result of exposure to neutron radiation. The superimposed effects of strain aging due to interstitial impurity atoms on radiation embrittlement were considered first by Wechsler, Hall and others. Here we summarize some of our efforts on the investigation of synergistic effects between interstitial impurity atoms (IIAs) and radiation-induced point defects, which result in interesting effects at appropriate temperature and strain rate conditions. Two materials, a mild steel and a pressure vessel steel (A516 Gr.70), are evaluated using tensile and three-point bend tests.