An Estimation Method of Long-Term Corrosion Fatigue Crack Growth Characteristics

Abstract

An estimation method of long-term growth characteristics of corrosion fatigue (CF) cracks using laboratory data is proposed based upon a linear summation model in terms of modified effective stress intensity factor range, ΔK_cont, which eliminates the corrosion products-induced wedge effect. Long-term CF crack growth curves of a 50 kgf/mm² high-tensile strength steel, HT50 and HT50-TMCP, and a 80kgf/mm² one, HT80, in synthetic seawater are estimated supposing that ΔK_cont is identical to the nominal stress intensity factor range, ΔK. The threshold values for long-term CF, ΔK_CF, deduced from these curves are nearly equal to the threshold values for crack initiation at corrosion pits, ΔK*_CF, which are calculated assuming the pits as sharp cracks.