各種ばね鋼SUP7の10^<10>回疲労特性(鉄鋼材料,<特集>ギガサイクル疲労)

概要

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Giga-cycle fatigue tests were conducted for heats B and C of SUP 7 spring steels tempered at 430 and 500℃. Rotating bending, electromagnetic, high-speed servohydraulic and ultrasonic fatigue testing machines were used at 30 or 100Hz, 120Hz, 600 or 800Hz and 20kHz, respectively. The heat B developed fish-eye fractures only with an origin of an Al_2O_3 inclusion, while Al_2O_3 and TiN inclusions and matrix cracks appeared at the origins in case of the heat C. The Al_2O_3 inclusions in the heat B were larger than those in the heat C. Hence, the heat C revealed higher fatigue limit than the heat B. In case of fish-eye fracture, S-N curves under 100Hz rotating bending, and 600 or 800Hz and 20kHz uniaxial loading were coincident each other in both heats, while those under 120Hz uniaxial loading were lower. The frequency effects were negligible in case of fish-eye fracture and the difference between 120Hz uniaxial tests and others were explained by the difference of the control volumes.
社団法人日本機械学会の論文
2004-08-25