軟鋼の塩水中疲労き裂伝播速度に及ぼす荷重繰返し速度,平均応力,温度および陰極防食の影響について

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In this report, the effects of cycle frequency, mean stress, temperature of corrosive and cathodic protection on the. fatigue crack growth of mild steel are examined by using the center-notched specimens under more extensive test conditions of corrosion fatigue than those in the previous report^<1)>. The results obtained are summarized as follows; ( 1 ) The correlation between the range of stress intensity factor ΔK and the crack growth rate da/dN for mild steel in 3% salt water could be given by the power's law shown in the following equation da/dN= C (ΔK)^<3. 5>, irrespective of the test conditions of corrosion fatigue such as cycle frequency f, mean stress and temperature of corrosive. ( 2 ) The coefficient C in above equation could be given, by the following equation C=-Alogf+B, where the coefficients A and B are material constants depending on the intensity and temperature of corrosive. ( 3 ) The crack growth rate under pulsating tension in salt water is unaffected by mean stress, and dependent on stress amplitude and cycle frequency. ( 4 ) The cathodic protection is scarcely valid for retarding the crack growth in salt water.
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