超音波疲労によるマルテンサイト系ステンレス鋼のギガサイクル疲労強度評価 : 異なる介在物寸法レベルの材料に関する検討(鉄鋼材料,<特集>ギガサイクル疲労)

概要

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Gigacycle fatigue properties of two martensitic stainless steels with different level of inclusion size were investigated by using ultrasonic fatigue tests at room temperature. As a result of the tests, the S-N curves for the both materials were straight on the downside. All of the fatigue fracture started from defects at the internal or at the surface. And almost fracture surfaces had facet regions around the defects. There were not facet regions under 2×10^5 cycles for SUS-A with larger level of inclusion and under 5×10^5 cycles for SUS-B with smaller level of inclusion. There were some specimens of SUS-B which didn't break in the regime from 10^9 to 10^<10> cycles, and which had smaller facet regions than those of the broken specimens. This gives a suggestion that the fatigue limit for internal fatigue fracture exists. For SUS-A and SUS-B, the √<area> parameter model with √<area>_<Fac> can explain whether a specimen breaks.
2004-08-25