３Ｄ積層により作成したマルエージング鋼の回転曲げ疲労特性に及ぼすショットピーニングの影響

抄録

Rotating bending fatigue tests were conducted to investigate the effect of shot peening on fatigue properties of maraging steels made by direct metal laser sintering process which was one of additive manufacturing processes. In order to investigate the effect of lamination direction of material, two types of specimen changed modeling pattern as horizontal modeling and vertical modeling were prepared. As the result of the fatigue test, non peened specimen was fractured from initial defect near the specimen surface, but the shot peened specimen was fractured from initial defect inside specimen where located 600µm deeper from surface of specimen. The size of initial defect differs according to the difference in modeling pattern and its size of the vertical modeling material was larger than the horizontal modeling material ones. However, threshold stress intensity factor at which specimen fracture of both materials were the same levels. The cause of this, fatigue limits of the vertical modeling material was slightly smaller than the horizontal modeling material ones. And then, since the final dimensions of the fish eye of both materials become the same, fatigue life of vertical modeling material shorter than horizontal modeling material.