人工海水中における80キロ級高張力鋼の腐食疲労き裂進展とカソード防食効果

概要

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Corrosion fatigue (CF) growth rate of a high-tensile strength steel has been measured in ASTM synthetic sea water at free corrosion and under a cathodic potential. The CF crack growth rate in synthetic sea water at free corrosion potential is nearly equal to the one in 3.5% NaCl solution at R=0.1 and 0.8. The CF crack growth characteristics under a cathodic potential can not be explained in terms of ΔK_<eff>, since Ca and Mg deposits-induced wedge effect enlarges the region II in the load-strain hysteresis loops. A revised effective stress intensity factor range ΔK_<cont>, deduced from the load range shared by regions I and II, is useful to explain the influence of cathodic potential on crack growth rate. The da/dN in synthetic sea water under a cathodic potential is almost the same as the fatigue crack growth rate in dry air near a threshold value of ΔK_<cont>. The cathodic protection becomes effective at a low ΔK_<cont>, whilst the one at a high ΔK_<cont> is much accelerated due to hydrogen embrittlement.
社団法人日本機械学会の論文
1986-08-25