1123 ラジカル窒化した球状黒鉛鋳鉄の高サイクル疲労における破壊起点(OS11-6 材料の疲労挙動と損傷評価-表面処理・締結材-)

概要

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High cycle fatigue strength of spheroidal graphite cast iron was remarkably increased by radical nitriding. By nitriding, thick and hard diffusion layer was formed and the compressive residual stress was induced. So, initiation of a fatigue crack was suppressed. In order to clarify the state of defects in fracture origin, fracture section was observed by using SEM. As a result, fracture starts at microshrinkages that exist on the neighboring surface at high stress rebels. On the other hand, fracture originated from inner microshrinkages and abnormal carbons at low stress rebels. And distance from the surface that the defects exist was deep as the stress decreased.
2010-10-09