鋳造用アルミニウム合金AC4A材の片振り引張疲労強度に及ぼす鋳物寸法、熱処理の影響

概要

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Influence of the casting size and the heat treatment (T6) on the fatigue strength of Al-Si alloy castings (AC 4A) under the repeated tension-tension loadings were examined. The fatigue strength decreased with increasing the casting size. T6 heat treatment increased the fatigue strength, but it decreased the ratio of 10^7σ_ωto σ_<UTS> from 1/2 to 1/3. Through the fractography using SEM, it was shown that the size of the porosity initiating the fatigue crack in the large casting was larger than its size in the small casting. Decreasing the size of porosity improved the fatigue strength. The effect of size of porosity on fatigue strength can be interpreted as the size of small notch on the propagation of short crack initiated at the porosity. Hardening the matrix microstrucutre by T6 heat treatment increased the notch sensitivity of porosity and decreased the ratio of fatigue strength and tensile strength.
一般社団法人日本機械学会の論文
1985-08-25