Effects of Dissolved Oxygen on Fatigue Characteristics of Austenitic Stainless Steel in 0.9wt% Sodium Chloride Solutions

概要

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Fatigue life evaluations in low dissolved oxygen conditions have been found to be conservative regarding the prediction of the fatigue strength of biomaterials. However, dissolved oxygen is considered to increase crack propagation rates. It is necessary to observe whether the strength in low dissolved oxygen conditions is higher. In this paper, the authors observed the effects of dissolved gas on the corrosion fatigue characteristics of austenitic stainless steels. Fatigue strength was higher with low dissolved O2 NaCl aq at a stress ratio of R= 0.1. However, fatigue strength did not change with low dissolved O2 NaCl aq at a stress ratio of R= 0.5 because of the effect of work hardening. Cycles to crack initiation were longer and crack growth rates were lower in the low dissolved O2 NaCl aq. The mechanism of decreasing fatigue strength can be explained by the oxidation process during slipping. In conclusion, dissolved oxygen has the effect of accelerating crack propagation processes.