Effect of Hydrogen Concentration on Fretting Fatigue Strength

概要

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Hydrogen concentration absorbed into material increases in long-term operation of hydrogen utilization machines. In this study, the effect of absorbed hydrogen on fretting fatigue strength was examined when the surface hydrogen concentration was sufficiently high. The concentration of absorbed hydrogen was changed by changing hydrogen charge time. The test material was pre-strained austenitic stainless steel SUS304. Hydrogen concentration at specimen surface was about 60ppm. Fretting fatigue strength was decreased and had a lower limit with increase of the hydrogen charge time. The amount of reduction of fretting fatigue limit due to hydrogen was 42% of fretting fatigue limit of uncharged specimen tested in air. In hydrogen gas, local adhesion between contacting surfaces occurred, and many small cracks emanated from both tips of the adhered part. These small cracks are one of the causes of the reduction of fretting fatigue limit.