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采用硅砂、宝珠砂和铬铁矿砂3种不同砂型作为造型材料浇注多阶梯铸件试样,对比研究不同冷却条件对Al-10Sr中间合金变质A356(Al-7Si-0.3Mg)铸造合金力学性能和显微组织的影响。结果表明:在3种造型材料中,铬铁矿砂浇注试样具有最好的组织和力学性能。随着冷却速度的增加,枝晶间距显著变小,力学性能有所改善,其中伸长率对冷却速度比抗拉强度更敏感。这种性能的提高主要是由于枝晶间距更加细密和基体中自由Sr原子数的提高造成的。根据实际的试验数据,模拟建立不同砂型条件下枝晶间距和力学性能之间的回归分析模型,该模型可用于预测Sr变质A356合金铸件的抗拉强度和伸长率。
The effects of different cooling conditions on the mechanical properties of Al-10Sr master alloy A356 (Al-7Si-0.3Mg) cast alloy and the effects of different cooling conditions on the mechanical properties, Effect of microstructure. The results show that the chromite samples have the best microstructure and mechanical properties among the three types of molding materials. As the cooling rate increases, the interdendritic spacing is significantly smaller and the mechanical properties are improved. The elongation is more sensitive to the cooling rate than the tensile strength. This performance improvement is mainly due to the dendrite spacing more closely and the matrix of free Sr atoms caused by the increase. Based on the actual experimental data, a regression analysis model was set up to simulate the interdendritic spacing and mechanical properties under different sand conditions. The model can be used to predict the tensile strength and elongation of Sr-modified A356 alloy castings.