球状黒鉛鋳鉄の疲労強度に及ぼす黒鉛の形状, 寸法, 分布の影響

概要

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Spheroidal graphite (SG) cast iron is a typical porous material which contains numerous small defects (graphites) in the matrix.In order to clarify the geometrical parameter for the quantitative evaluation of the effect of surface graphite on the fatigue stength f SG cast iron, rotating bending fatigue tests were carried out on the plain- and notched-specimens of as-cast FCD60 and FCD70. It is concluded from the microscopic observation that the fatigue limit is controlled by the maximum size of surface graphite defined by the square root of the projected area of graphite (√<area>^*_<max>). The value of √<area>^*_<max> in a definite surface area of the specimen can be predicted by the statistics of extreme values. The predicted values of √<area>^*_<max> approximately agree with the critical size of artificial notch which does not act to reduce the fatigue strength. The value √<area>^*_<max> is in general considered to be th controlling geometrical parameter for the prediction of fatigue strength of porous materials.
社団法人日本材料学会の論文
1989-10-15