Characterizations of creep crack growth in 1 per cent Cr Mo V steel

Abstract

Estimates of stress intensity factor, K, reference stress, σ_ref, and creep parameter, C∗, have been made for compact tension (CT) and double cantilever beam (DCB) test-pieces containing side grooves. Limit analysis techniques were used to determine the latter two parameters. It is shown that the expressions developed for σ_ref are sensitive to the collapse mode proposed, whereas those for C∗ are largely independent. Comparisons of predictions of creep crack growth data on CT and DCB specimens of a 1 per cent CrMoV steel in terms of K and σ_ref have revealed different dependences for the two geometries, suggesting that neither parameter gives satisfactory correlations. Better overall agreement is obtained with the C∗ parameter, even though gross creep deformations were not observed. It is suggested that further improvement may be gained with this parameter if more accurate estimates of C∗, which allow the inclusion of elastic terms, are used.