Comparison of environmentally-influenced near-threshold fatigue-crack-growth behavior in high- and lower-strength steels at conventional frequencies
Recent studies in a wide variety of steels, of yield strengths ranging from 290 to 1740 MPa, have indicated that environmental influences on corrosion fatigue crack propagation at near-threshold levels (growth rates below approx. 10/sup -6/ mm/cycle), may be markedly different from those at higher growth rates. In this paper, the effect of such environments, specifically dry gaseous hydrogen and moist room air, on near-threshold cyclic crack growth is reviewed and comparisons made between behavior in high and lower strength steels. It is shown that, in lower strength steels (yield strength less than or equal to 700 MPa), near-threshold growth rates in dry hydrogen exceed those in moist air by up to two orders of magnitude at low load ratios only, whereas for steels of strength levels above approx. 700 MPa, the presence of hydrogen results in lower near-threshold growth rates compared to moist air regardless of load ratio. Such behavior is rationalized in terms of the competing effects of hydrogen embrittlement and oxide-induced crack closure mechanisms.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA); Westinghouse Research and Development Center, Pittsburgh, PA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5228208
- Report Number(s):
- LBL-13571; CONF-8110183-1; ON: DE82014992
- Resource Relation:
- Conference: Engineering foundation conference on fatigue and corrosion fatigue up to ultrasonic frequencies, Champion, PA, USA, 25 Oct 1981
- Country of Publication:
- United States
- Language:
- English
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