The applicability of the C∗ parameter for the prediction of creep crack propagation rates is considered. A new method for estimating C∗ is presented, the results from which show good agreement with those from an existing technique. Experimental results from creep crack growth tests, conducted on a 1 Cr Mo V steel using both compact tension and single edge notch bend specimens, indicate that good correlation with C∗ is obtained once the effects of stress redistribution become negligible. Finally, comparisons are drawn between C∗ and other possible correlating parameters, and the limitations of each approach are discussed.
Get full access to this article
View all access options for this article.
References
1.
EllisonE. G.NeateG. J.‘Life prediction methods for cracked components operating in the creep range’, Conf. Failure of Components Operating in the Creep Range Instn mech. Engrs, April 1976.
2.
WilliamsA. J.PriceA. T.‘A description of crack growth from defects under creep conditions’, J. Eng. Mat. Tech., Trans. Am. Soc. mech. Engrs, Paper 75-Mat-H 1975.
3.
HarperM. P.EllisonE. G.‘Prediction of creep crack propagation rates’, Meeting on Creep Crack Growth Metals Society, Sheffield, Jan. 1976.
4.
EllisonE. G.HarperM. P.‘The influence of constraint on creep fracture’. To be published.
5.
HayhurstD. R.MorrisonC. J.LeckieF. A.‘The effect of stress concentration on the creep rupture of tension panels’, J. appl. Mech., Trans. Am. Soc. mech. Engrs, Paper No 75-APM-R, 1975.
6.
LandesJ. D.BegleyJ. A.Fracture mechanics approach to creep crack growth Westinghouse Scientific Paper 74–1E7-FESGT-P1, 1974.
7.
WebsterG. A.‘The application of fracture mechanics to creep cracking’, Conf. on Mechanics and Physics of Fracture, Inst. Physics, Cambridge 1975.
8.
NikbinK.WebsterG. A.TurnerC. E.‘Relevance of nonlinear fracture mechanics to creep cracking’, to be published, 1976.
9.
RiceJ.RosengrenG.‘Plane strain deformation near a crack tip in a power law hardening material’, J. Mech. Phys. Sol.196816, 1–12.
10.
HutchinsonJ.(a)‘Singular behaviour at the end of a tensile crack in a hardening material’, J. Mech. Phys. Sol.196816, 13–31. (b) ‘Plastic stress and strain fields at a crack tip’, Ibid, 337–347.
11.
HoffN. J.‘Approximate analysis of structures in the presence of moderately large creep deformations’, Quart. appl. Math.195412, 49–55.
12.
OdqvistF. K. G.Mathematical theory of creep and creep rupture1966 (Clarendon Press, Oxford).
13.
BegleyJ.LandesJ. D.‘TheJ integral as a fracture criterion’, A.S.T.M. STP 514, 1–20, 1972.
14.
EwingD. J. F.RichardsC. E.‘The yield point loads of singly-notched pin-loaded tensile strips’, J. Mech. Phys. Sol.197422 (1), 27–36.
15.
HaighJ. R.RichardsC. E.Yield point loads and compliance functions of fracture mechanics specimens C.E.G.B., C.E.R.L. Report RD/L/M461, 1974.
16.
LandesJ. D.Private communication, 1976.
17.
EllisonE. G.WaltonD.‘Fatigue, creep, and cyclic creep crack propagation in a 1 CrMoV steel’, Int. Conf. Creep and Fatigue in Elevated Temperature Applications Instn mech. Engrs, Philadelphia/Sheffield, 1973/1974.
18.
GilbeyD. M.PearsonS.Measurement of the length of a central or edge crack in a sheet of metal by an electrical resistance method R.A.E. Report No TR 66402, 1966.
19.
NeateG. J.Private communication, 1976.
20.
GoodallI. W.ChubbE.‘The creep ductile response of cracked structures’, Int. J. Fracture197612 (No 2).
21.
GoodallI. W.Private communication, 1976.
22.
NeateG. J.The application of fracture mechanics to creep crack growth in ½Cr½Mo1/4V steel C.E.G.B. Report No SSD MID/R12/74.
23.
HaighJ. R.‘The mechanisms of macroscopic high temperature crack growth, Part I - Experiments on tempered CrMoV steels; Part II - Review, reanalysis of previous work’, Mat. Sci. Engng197520, 213–235.
24.
HayhurstD. R.KellyD. A.LeckieF. A.MorrisonC. J.PonterA. R. S.WilliamsJ. J.‘Approximate design methods for creeping structures’, Int. Conf. Creep and Fatigue in Elevated Temperature Applications Philadelphia/Sheffield. Instn mech. Engrs, 1973/74.
25.
LeckieF. A.HayhurstD. R.MorrisonC. J.‘Creep behaviour of sphere-cylinder shell intersections subjected to internal pressure’, 2nd Int. Conf. Structural Mechanics in Reactor Technology Berlin, 1973.
