Remaining-life estimation of boiler pressure parts: crack growth studies. Final report. [1 1/4 Cr-1/2 Mo header material]
A methodology for predicting the remaining creep crack growth life in boiler thick section components has been developed. The creep crack growth behavior of a 1-1/4Cr-1/2Mo header material can be characterized by the C/sub t/ parameter over a wide range of crack growth rates and under conditions ranging from small-scale to large-scale creep. Limited finite-element results show that C/sub t/, as measured at the loading pins of test specimens, can be used as a measure of the crack tip stress field in the non-steady-state creep regime. This may be the reason that C/sub t/ characterizes creep crack growth behavior. The experimentally measured values of C/sub t/ in compact-type specimens compared well with those obtained from the general analytical equations developed in this program. Analytical equations have been formulated for estimating C/sub t/ in structural components. The creep deformation rates and the creep crack growth rates of the material machines from the hot region of the header were found to be greater than those from the cold region. Varying the specimen diameter from 1.98 to 12.83 mm did not affect creep deformation and rupture data. The developed life prediction methodology is demonstrated by using two hypothetical examples of a cracked header-like component and an elevated-temperature steam pipe. 39 refs., 49 figs., 11 tabs.
- Research Organization:
- Westinghouse Electric Corp., Pittsburgh, PA (USA). Materials Analysis Dept.; Georgia Inst. of Tech., Atlanta (USA). Fracture and Fatigue Research Lab.
- OSTI ID:
- 5503658
- Report Number(s):
- EPRI-CS-4688; ON: TI86920416
- Country of Publication:
- United States
- Language:
- English
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