SEDL / STP / STP803V2-EB / STP36790S

An Elastic-Plastic Fracture Mechanics Study of Crack Initiation in 316 Stainless Steel

Davies, PH
Research engineer, Ontario Hydro Research Division, Toronto, Ont.

Pages: 21    Published: Jan 1983

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Abstract

An experimental study of crack initiation in solution-treated 316 stainless steel was undertaken to test the validity of the elastic-plastic fracture mechanics parameters, J and crack opening displacement (COD), in the presence of extensive yield. Measurements of the J-integral are obtained for 6.4 to 25-mm-thick compact specimens using the proposed ASTM equation. The latter is shown to give results within 2 percent of those obtained using the original calibration method of Begley and Landes. However, deviations from the proposed crack blunting line, J = 2σfΔa are found for this high work-hardening material. Midsection COD is also determined using a rubber infiltration technique. Critical values of the J-integral and COD at crack initiation are shown to be constant independent of plate thickness under plane-strain and non-plane-strain crack-tip conditions as defined by B = 25 to 50 (Ji/σf) and B = 25 CODi. These results are supported by measurements of the surface crack-tip contraction.