海水浸漬腐食を施した18-8ステンレス鋼の疲労強度

概要

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When 18-8 stainless steel is soaked in sea water. a local attack is formed by adhesion of microbes cmparatively in a short time. In order to investigate the effects of corrosion defects on the fatigue strength of this material. we carried out the rotating beam fatigue tests of plain specimens and notched specimens with stress concentration factor. α=2. 0, 3. 3, 4. 9, which were soaked in sea water for 3 months, 6 months and 12 months. The results obtained are as follows. (1) The fatigue limit of plain specimens and that of notched specimens with α=2. 0 and 3. 3 are on the decrease with the soaked periods shortened. The lowering ratio during the 12 months stood at 33%, 27% and 19%, respectively. (2) The corrosion defects in the order of crack. pin hole. line and pit have a deteriorative influences upon the fatigue strength. (3) The lowering of fatigue limit of notched specimens with α =4. 9 is not recognized. for this is the strength with nonpropagating crack. (4) In the case of notched specimens with α=2. 0 and 3. 3 notch strengthening is found out, because of formation of martensite by plastic deformation at the notch root.
社団法人日本材料学会の論文
1969-05-15