高強度鋼の二段折れ曲がりS-N曲線の形態に及ぼす清浄度の影響

概要

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In order to study the effect of cleanliness on the step-wise S-N characteristics of high strength steel, cantilever-type rotary bending fatigue tests were conducted in laboratory air at ambient temperature on two kinds of high carbon chromium steels with different cleanliness. In surface-related fracture region, fatigue strength was not dependent on cleanliness, while in subsurface fracture region, the steel with higher cleanliness showed shorter fatigue life and higher transition stress at which the crack initiation site changed from the surface to the subsurface. These were attributed to larger size of inclusions contained in the steel with higher cleanliness. It was confirmed that cleanliness, defined with the number of inclusions, was not a factor controlling subsurface fracture. The S-N characteristics depending on the inclusion size were further discussed on the basis of the relationship between stress intensity factor for inclusion and fatigue life and the size of inclusions from which subsurface fracture occurred.
一般社団法人日本機械学会の論文
2003-10-25