712 20kHz 及び 600Hz でのギガサイクル疲労試験

概要

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Fatigue tests were carried out at frequencies of 20kHz, 600Hz and 100Hz for low-temperature-tempered SNCM439 steel. Ultrasonic, high-speed servohydraulic and electromagnetic fatigue test machines were used for 20kHz, 600Hz and 100Hz tests, respectively. The fatigue tests showed that fatigue properties were independent of the frequencies, while fatigue lives were scattered on the S-N diagram. Almost all specimens were broken from internal Al_2O_3 inclusions of various sizes between 9 and 82μm. ODAs were observed in all specimens broken over (10)^7 cycles. ODA sizes were also independent of the frequencies. The scattered S-N diagram was found to be expressed by an unique curve by normalizing stress amplitudes σ_a with fatigue limits σ_w estimated by Murakami's equation. The modified S-N diagram showed a clear fatigue limit between (10)^9 and (10)^<10>cycles.
社団法人日本機械学会の論文
2002-10-10