锶变质AlSi7Mg0.3合金力学性能衰退的研究

A Study on Fading in Mechanical Property of Strondium modified AlSi7Mg0.3 Alloy

在生产条件下研究了保温时间对锶变质ＡｌＳｉ７Ｍｇ０．３合金力学性能的影响。保温时间延续６０ｍｉｎ以后，合金伸长率和冲击韧度下降了２０％，抗拉强度下降了５％，而硬度未发生变化。在此期间锶含量质量分数（０．００４％～０．００５％Ｓｒ）皆超过有效变质临界下限值（０．００３％Ｓｒ）。铝合金力学性能的衰退可能与吸气引起的密度降低、针孔数量增加有关。

The effect of holding on the mechanicl property for Sr modified AlSi7Mg0.3 alloy has been studied under industrial condition. During Super holding over 60 min. The loss of elongation and toughness is incurred about 20%, compared to loss of 5% in tensile strength, but the hardness is unchanged with time. In this period the Sr content of 0.004% ￣ 0.005% in melt is much more than that (0.003%Sr) required for critical modification. The mechanical property fading for Al alloy would be attributed to attributed lowering of density and increasing of pin hole.