水素供給下における高強度鋼の疲労き裂進展挙動に及ぼす平均荷重の影響

概要

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The effect of mean load on the fatigue crack growth behavior of a high strength steel has been investigated. The material used was SNCN 439 tempered at 200℃. The specimens were loaded in in-plane bending at a cvclic frequency of 2000 cycles per minute at various stress ratios (R) and mean stress intensity factors (K_<mean>) under hydrogen supply. The results of fatigue crack growth at various stress intensity range (ΔK) were arranged in terms of K_<mean> and maximum stress intensity (K_<max>) in order to characterize the effect of mean load. at all ΔK levels, the acceleration of crack growth rate occured beyond the level of K_<mean>= K_<ISCC>. In the region of K_<mean><K_<ISCC>, the fatigue crack growth behavior on ΔK level, irrespective of K_<mean> level. On the other hand, in the region of K_<mean> >K_<ISCC>, crack growth was dominated by K_<max> level. These results were also confirmed by fractographic ovservations.
社団法人日本材料学会の論文
1985-11-15