Creation of high fatigue strength material using high hardness layer and development of the prediction method of its fatigue life

本研究旨在提出一种新的表面涂层方法并探讨其形成机理，同时探讨表面硬化层对金属材料超高周疲劳性能的影响。作为疲劳试验的结果，表面硬化材料的疲劳强度根据表面层而变化。这是因为疲劳断裂模式根据表面层的机械性能和厚度而改变。从表面硬化材料的局部弯曲应力分布的角度阐明了疲劳断裂机理。

The purpose of this study is to propose a new surface coating method and investigate its formation mechanism, and to investigate the effect of surface hardened layer on the very high cycle fatigue properties of metallic materials. As results of fatigue tests, the fatigue strength of surface hardened material changed depending on the surface layer. This was because the fatigue fracture mode changed depending on the mechanical property and thickness of the surface layer. The fatigue fracture mechanism was clarified from view points of the local bending stress distribution applied to the surface hardened material.