SEDL / STP / STP513-EB / STP34119S

Extensive Study of Low Fatigue Crack Growth Rates in A533 and A508 Steels

Paris, PC
Del Research Corporation, Hellertown, Pa.

Bucci, RJ
Del Research Corporation, Hellertown, Pa.

Wessel, ET
Westinghouse Research, Pittsburgh, Pa.

Clark, WG
Westinghouse Research, Pittsburgh, Pa.

Mager, TR
Westinghouse Nuclear Energy Systems(PWRSD), Pittsburgh, Pa.

Pages: 36    Published: Jan 1972

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Abstract

For two heats of ASTM A533 Grade B Class 1 pressure vessel steel and an ASTM A508 Class 2 forged steel, an extensive study of fatigue crack growth rate characteristics was conducted within the framework of linear elastic fracture mechanics. Experimental data obtained covered a wide variation in cyclic growth rates ranging from those associated with fatigue threshold (order of 10^-9 in./cycle) up to rapid fracture. The bulk of experimental information obtained was at very low cracking rates, usually 10^-6 in./cycle and below. Considered in the investigation were: (1) an evaluation of the effect of stress ratio, R = σ^min/σ^max, on verv slow rates of fatigue crack extension; (2) an evaluation of temperature (75 to 650 F) on very slow rates of fatigue cracking; (3) an examination of the combined effects of temperature and stress ratio and their influence on fatigue crack extension; (4) an evaluation of the effect of a distilled water environment on fatigue crack propagation rates; (5) an examination of the effects of specimen thickness; and (6) a comparison of results for two separate heats of the same alloy.