Impact of long term exposure on corrosion fatigue crack growth of low alloy steels
- National Physical Lab., Teddington (United Kingdom). Centre for Materials Measurement and Technology
The effect of long term pre-exposure on the corrosion fatigue crack growth rates of low alloy steels has been studied in order to provide guidance on the reliability of short term testing. Tests were conducted in aerated 3.5% NaCl at a potential of {minus}1,100 mV(SCE) using a sinusoidal loading wave with a stress ratio of 0.25 and a frequency of 0.167 Hz. Pre-exposure of AISI 4340 for 21 weeks enhanced the crack growth rates by up to a factor of 7 relative to data from conventional tests which lasted about 4 weeks. Pre-exposure of 3.5% Ni-Cr-Mo-V steel for 55 weeks increased the corrosion fatigue crack growth rates by up to a factor of 4 relative to results from a conventional 4 week test. There was some indication of an effect of pre-exposure on the corrosion crack growth rates of BS4360 50D at values of {Delta}AK below 13 MPam{sup {1/2}} but the scatter in the data prevented a definitive conclusion. The crack growth rates measured in conventional (ie short term) tests were broadly similar for AISI 4340, 3.5% Ni-Cr-Mo-V and BS4360 50D steels at values of {Delta}K above 13 MPam{sup {1/2}}. The crack growth rates of specimens pre-exposed before testing were comparable for 3.5% Ni-Cr-Mo-V and BS4360 50D steels but up to a factor of 5 greater for AISI 4340.
- OSTI ID:
- 397835
- Report Number(s):
- CONF-960389--
- Country of Publication:
- United States
- Language:
- English
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