チルプレート上で急冷凝固させたAl-17%Si合金薄板の平滑性に及ぼすリンの影響

抄録

  Recently, to reduce the weight of automobiles, the thickness of aluminum alloy castings is increasingly being reduced. For the thickness reduction of the casting, Hypereutectic Al-Si alloy is considered promising for reducing the thickness of casting because it exhibits excellent fluidity. On the other hand, thinned castings are generally not machined and should be flat surfaced. The flatness of hypereutectic Al-Si alloy has rarely been reported to date. Accordingly, in this study, Al-17% Si alloy was pelted without restraint on a chill plate by changing the P content to determine the influence of P on the flatness of thin plate. The results are as follows. In alloys containing no or 25ppm P, spots without eutectic cells were formed on the surface. As small solidified shells between these spots transformed into waveform, the surface of thin plate was not flat. In contrast, eutectic cells were continuously formed on the surface in the alloy containing 112ppm P. Consequently, as large solidified shells were formed, no transformation occurred and the thin plate surface was flat.