Development of high strength Al alloys produced by newly proposed high speed continuous casting

本研究开发了高速热型连铸工艺。采用该铸造工艺可生产出高质量的铸件，其力学性能(高强度和高塑性)约为传统重力铸造同类合金的两倍。采用具有不同组织特征(SDAS和共晶组织)的试样，研究了拉速对力学性能的影响。SDAS与拉伸性能之间存在线性相关关系。然而，当共晶组织的直径超过0.003 mm时，当UTS和塑性显著降低时，这些线性相关性被打破，特别是UTS与SDAS和应变与SDAS的相关性。对于大于0.003 mm的共晶组织，断裂以脆性共晶相为主，SDAS与UTS和应变不再有很强的相关性。

In this research, the high speed heated-mold continuous casting process was developed. With this casting process, high quality cast samples were produced, which exhibit excellent mechanical properties (high strength and high ductility) that are about twice as high as those for the same alloy produced by conventional gravity casting. The effects of casting speed on the mechanical properties were investigated, using the samples with different microstructural characteristics (SDAS and eutectic structures). There are linear correlations between SDAS and tensile properties. These linear correlations, however, break down, especially for UTS versus SDAS and strain versus SDAS, as the eutectic structures become more than 0.003mm in diameter, when the UTS and ductility decrease significantly. For eutectic structures larger than 0.003mm, failure is dominated by the brittle eutectic phases, for which SDAS is no longer strongly correlated with UTS and strain.