Review of the corrosion fatigue performance of medium to high strength structural steels
- Cranfield Univ. (United Kingdom)
- Health and Safety Executive, London (United Kingdom)
Despite the increasing application in recent years of high strength steels in the offshore industry, their use in the fabrication of conventional jacket structures is generally restricted to steels with yield strengths in the range 450--550 MPa and to topside applications. One reason is the uncertainty associated with the performance of these materials and the concern that such steels have inferior fatigue performance compared to conventional structural steels with typical yield strengths of 350 MPa, particularly when welded and cathodically protected. In this paper, published work from Europe, USA and Japan is reviewed to provide a judgment as to the suitability of these higher strength steels for offshore applications. Fatigue crack propagation data for a range of steels in the yield strength range 400--600 MPa are compared with data for conventional BS4360:50D structural steels. Information for parent plate and heat affected zones is included. The influence of environment is examined and test data for in-air, free corrosion, and cathodic protection potentials ranging from {minus}800 to {minus}1100mV (SCE) are considered. The data for parent materials suggest that comparable or slightly improved performance compared with that of structural Grade 50D steels can be obtained in both air and seawater environments. However, the review highlights the combined detrimental influence of high mean stress and overprotection levels, (i.e., {minus}1100mV), which can cause crack growth rates to be increased by a factor of 10 compared with those observed in-air. The results suggest that welding under controlled conditions does not significantly affect fatigue crack propagation in these steels, with similar corrosion fatigue performance and crack growth mechanisms observed in parent material and in the HAZ.
- OSTI ID:
- 403639
- Report Number(s):
- CONF-9606279--; ISBN 0-7918-1492-0
- Country of Publication:
- United States
- Language:
- English
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