窒化により表面改質した純鉄と純チタンの疲労特性の比較

概要

論文の詳細を見る
The purpose of this study was to determine the effect of nitriding, used as a surface-modification method on the fatigue strength of metals. By conducting experiments for evaluation of the factors controlling the fatigue strength of nitrided pure iron and titanium, we obtained the following results. (1) The improvement in the fatigue strength of nitrided pure iron results from the fact that the hardened case existing under the compound layer suppresses the propagation of cracks. However, the fatigue strength of nitrided pure titanium decreases because a crack initiated in the compound layer at a low stress level directly results in the overall fracture of the brittle hardened case. (2) There is a Hall-Petch relationship between grain size and the fatigue strength of nitrided pure iron and titanium. This effect does not influence the fatigue strength of nitrided pure iron because the grains do not grow during nitriding. In contrast, the above effect results in the inferior fatigue strength of nitrided pure titanium because grain growth inevitably occurs during nitriding at high temperatures.
1997-01-25