水素チャージしたＳ１０Ｃの低サイクル疲労特性への水素量とひずみ速度の効果

概要

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Strain-controlled low-cycle fatigue tests have been conducted on hydrogen charged JIS S10C steel, and the effects of hydrogen content and strain rate have been examined. Decrease of hydrogen content from 1. 5 to 0. 5mass-ppm is effective in improving the fatigue life. But it is still far less than that of non-charged steel, bearing the fish-eye type fracture surface. The fatigue life is fully recovered by hydrogen discharge at room temperature for 20 minutes. Estimating the hydrogen distribution after this discharging, 0. 4mass-ppm is obtained as the critical hydrogen content, under which hydrogen does not reduce the fatigue life. Further, the fatigue life of hydrogen charged specimen is improved reasonably, when the strain rate is increased from 0. 001 to 0. 003⁄s. Extrapolation of this results suggests that higher strain rate than 0. 02-0. 03⁄s would not decrease the fatigue life of hydrogen charged specimens. Further stress amplitudes exhibits negative strain rate dependence after hydrogen charging, suggesting dynamic strain aging. In this case, interaction between dislocation and hydrogen-vacancy pair might be responsible, instead of hydrogen atom alone
一般社団法人日本高圧力技術協会の論文