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 -1100 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. Preexposure 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 ...
Keywords: corrosion fatigue, low alloy steels, pre-exposure, cathodic protection, hydrogen, diffusion