Al-Si 系鋳造合金の疲労ならびに衝撃特性に及ぼす各種改良元素の影響

概要

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The fatigue and impact properties of Aluminum-Silicon casting alloys modified by various elements were investigated. The form of eutectic Si particle was different by each modification element. From the quantitative analysis, the round factor of the eutectic Si was about the same by each modification element with T6 treatment, but the particle sizes were different and was largest by Li treatment, followd by Sr treatment and smallest by Sb and Na treatment. The fatigue and impact properties were influenced by the eutectic Si forms depending on different modification element. The eutectic Si particle forms of the alloy modified by Sb were more spherical and finally dispersed, that resistance against crack initiation and propagation was higher. The fatigue limits of alloys modified by Sb and Na were highest, while Sr and Li treatment were lower. However, alloy modified by Sr had shown highest fatigue strength at less than 5×106 cycles. The alloy modified by Sb had shown lowest fatigue crack growth rate both for high and low ΔK values and had shown maximum stress intensity factor range at lower limit. The fatigue crack growth rate of Na modified alloy was lower in low ΔK range compared with Sr or Li modification, corresponding to this, range of lower limit of stress intensity factor was larger, however, it was lower at high ΔK range.
Japan Foundry Engineering Societyの論文