SYMPOSIA PAPER Published: 01 January 1973

Threshold for Fatigue Crack Growth in Ferritic Steels at 300 C


Edge-cracked test specimens of two ferritic steels were subjected to the loading cycle σm ± σa at 300 C. The results showed that whether a crack grows or remains dormant can be predicted from the value of ΔK, the range of stress intensity factor during the fatigue cycle. The threshold value ΔKc necessary for crack growth was slightly greater than that of similar steels at room temperature and depended on the ratio σma. Crack growth data at low rates of crack growth were deduced from an integrated version of the crack growth equation da/dN = BK)m, where B and m are material constants. Crack growth rates at 300 C were similar to those at room temperature. The minimum possible rate of fatigue crack growth appeared to be somewhat greater than one lattice spacing/cycle. The methods used have the advantage that no crack growth monitoring instrumentation is required.

Author Information

Pook, LP
National Engineering Laboratory, East Kilbride, Glasgow, Scotland
Beveridge, AA
National Engineering Laboratory, East Kilbride, Glasgow, Scotland
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Developed by Committee: E08
Pages: 179–191
DOI: 10.1520/STP38839S
ISBN-EB: 978-0-8031-5576-3
ISBN-13: 978-0-8031-5528-2