ハードショットピーニングによるマルエージング鋼の疲労強度向上

概要

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Rotating bending fatigue tests were carried out for an 18%Ni maraging steel to investigate the effect of hard shot peening on the fatigue strength. The fatigue strength increased markedly by the shot peening. In the case of single shot peening, the increase in the fatigue strength due to the shot peening depended on the shot size and the stress level. Fracture mode changed from the surface fracture in the short life region to the interior fracture in the long life region. And in the middle life region, both cracks initiated from the surface and the inside of material and lead to the final fracture. On the otherhand, in the case of double shot peeing, the fatigue strength in the short life region is greatly increased irrespective of the size of shot particles. The high fatigue strength is due to very small surface roughness and high compressive residual stress generated just under the surface due to the second stage of double shot peening using super-hard fine particles. These results were discussed from the effect of shot size on the surface roughness and the depth and magnitude of compressive residual stress and work hardening.
都城工業高等専門学校の論文