Papers by Author: Satoshi Fukui

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Authors: Satoshi Fukui, Riichi Murakami, Daisuke Yonekura
Abstract: Four point bending fatigue tests were carried out using martensitic stainless steel with TiN film deposited at five different deposition rates by dynamic ion mixing process in order to investigate the influence of deposition rate on the fatigue strength. As a result, the fatigue limit clearly increased by the deposition at appropriate conditions. However, the deposition by other conditions resulted in the degradation of fatigue strength. This is caused by the decrease of threshold stress intensity factor after TiN deposition and the difference of defect distribution in the film. In addition, the crack propagation rate was increased in low stress intensity factor range by the deposition of TiN film.
Authors: Nu Yan, I. Lee, Riichi Murakami, Daisuke Yonekura, J. Sun, Satoshi Fukui
Abstract: The effect of plasma radical nitriding treatment on fatigue properties of SCM435 steel in super long life region was investigated. Fatigue tests were carried out using a dual-spindle rotating bending fatigue-testing machine at room temperature in air for the specimens nitrided at 773 K and 823 K for 3 hrs. The fatigue strength of nitrided specimen was greater than that of un-nitrided specimen and the crack initiation mode changed from the surface cracking of un-nitrided specimen to the subsurface cracking of nitrided specimen. Hardening layer and compressive residual stress were formed by nitriding, which resulted in the improvement of the fatigue strength. The stress intensity factor was calculated using facet area in Fish-eye fracture mode. As a result, the stress intensity factor indicated almost constant value, ~ 3-4 MPa·m1/2, regardless of the number of cycles to failure.
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