EFFECT OF SPECIMEN SIZE ON THE IMPACT PROPERTIES OF NEUTRON-IRRADIATED A533B STEEL

A new methodology is proposed to correlate the upper shelf energy (USE) of full-size and subsize Charpy specimens of a nuclear reactor pressure vessel plate material. The methodology appears to be more satisfactory than those methodologies proposed earlier. The USE was normalized by a normalization factor involving the dimensions of the Charpy specimen, the elastic stress concentration factor, and the plastic constraint at the notch root. The normalized values of the USE were found to be invariant with specimen size. In addition, it was also found that the ratio of the USE of unirradiated to that of irradiated materials was approximately the same for full-, half-, and third-size specimens. The ductile-to-brittle transition temperature (DBTT) increased due to irradiation at 150 degrees C to a nominal fluence of 1.0 x 10(19) n/cm(2) (E > 1 MeV) by 78, 83, and 70 degrees C for full-, half-, and third-size specimens, respectively. These shifts in DBTT appeared to be independent of specimen size and notch geometry.