Compressive Pre-Strain Effects on the Creep and Crack Growth Behaviour of 316H Stainless Steel

The effects of compressive plastic pre-strain on the creep deformation and crack growth behaviour of Type 316H stainless steel have been examined. Creep crack growth (CCG) tests have been performed on compact tension specimens of material which had been uniformly pre-strained by 4% and 8% in compression at room temperature. The CCG behaviour of the pre-compressed material has been interpreted in terms of the creep fracture mechanics parameter C* and compared with that of a significant data set of as-received (un-compressed) specimens and with CCG models. All creep testing has been performed at a temperature of 550 °C. High CCG rates, for a given value of C* have been observed for the pre-compressed material, compared with those of as-received material and these data follow the same trends as the long-term CCG data for as-received material. These observations are explained in terms of specimen constraint effects and variations in creep ductility.