熔体搅拌工艺对过共晶Al-Si合金P变质效果的影响
发布时间：2018-10-14 11:35
【摘要】：过共晶Al-Si合金具有热膨胀系数小、热稳定性好、低密度、高硬度、耐高温、耐磨等特点,在发动机零部件等领域具有较好的应用前景。对于过共晶Al-Si合金而言,通常采用变质处理的方法来细化初生硅。众多的变质处理方法中,P变质细化初生硅效果明显且稳定、易行。含P中间合金加入到过共晶Al-Si合金熔体后,需要对熔体进行搅拌才能获得较好的变质处理效果,但是,搅拌的程度对变质处理效果有何影响规律并不清楚。本文以Al-15%Si合金、Al-18%Si合金、Al-20%Si合金为研究对象,采用Cu-9%P合金进行变质处理,研究变质后熔体搅拌工艺对变质效果的影响规律,为充分发挥P的变质作用提供理论依据。本实验研究结果表明,对于Al-20%Si合金而言,在高于Cu-9%P合金熔化温度以上搅拌时,搅拌越激烈,细化效果越好;随着搅拌时间的延长,初生硅平均尺寸呈现出先减小后增大的变化规律。当搅拌速度为224rad/min、搅拌时间为8min时,初生硅平均尺寸细化到17μm。对于Al-15%Si合金、Al-18%Si合金、Al-20%Si合金,在低于Cu-9%P合金熔化温度以下搅拌时,随着搅拌时间的延长,初生硅平均尺寸大体上呈现出先减小后增大的规律。搅拌越激烈,在最佳搅拌时间内初生硅细化效果越好,搅拌时间过长,初生硅尺寸增加得越大。高转数搅拌时(224rad/min),最佳搅拌时间与Si含量无关,均在20min时细化效果最好;低转数搅拌时(75rad/min),Si含量不同时最佳搅拌时间不同。对于Al-15%Si合金、Al-18%Si合金、Al-20%Si合金,当搅拌速度为224rad/min、搅拌时间为20min时,初生硅平均尺寸分别细化到9μm、17μm、12μm,并且在Al-20%Si合金中典型的共晶组织消失,出现了颗粒状的共晶硅。Si含量越高,初生硅平均尺寸降低的越多,细化效果越明显。
[Abstract]:Hypereutectic Al-Si alloys have the advantages of low thermal expansion coefficient, good thermal stability, low density, high hardness, high temperature resistance and wear resistance. For hypereutectic Al-Si alloys, modification is usually used to refine primary silicon. Among the many modification methods, the effect of P modification on refining primary silicon is obvious, stable and easy to carry out. After adding P-containing master alloy into the melt of hypereutectic Al-Si alloy, it is necessary to stir the melt to obtain a better modification effect. However, it is not clear how the degree of stirring affects the modification effect. In this paper, Al-15%Si alloy, Al-18%Si alloy and Al-20%Si alloy are taken as research objects. The modification of Cu-9%P alloy is carried out, and the influence of melt stirring process on modification effect is studied, which provides a theoretical basis for giving full play to the modification of P. The experimental results show that, for Al-20%Si alloy, the more intense the stirring is, the better the refining effect is when the stirring temperature is higher than the melting temperature of Cu-9%P alloy, and with the prolongation of stirring time, The average size of primary silicon decreases first and then increases. When the stirring speed is 224rad / min and the stirring time is 8min, the average size of the primary silicon is refined to 17 渭 m. For Al-15%Si alloy, Al-18%Si alloy and Al-20%Si alloy, when the stirring temperature is below the melting temperature of Cu-9%P alloy, the average size of primary silicon decreases first and then increases with the prolonging of stirring time. The more intense the stirring, the better the refining effect of primary silicon is in the optimum stirring time, the longer the stirring time is, the larger the size of primary silicon is. The best stirring time was not related to the content of Si, but the thinning effect was best when 20min was used, and when the content of 75rad/min), Si was different, the optimum stirring time was different when the 75rad/min), Si content was different. For Al-15%Si alloy, Al-18%Si alloy and Al-20%Si alloy, the average size of primary silicon was refined to 9 渭 m ~ 17 渭 m ~ (12) 渭 m when stirring speed was 224rad / min and stirring time was 20min. The typical eutectic structure disappeared in Al-20%Si alloy, and the higher the content of Si was, the more granular eutectic silicon appeared. The more the average size of primary silicon decreases, the more obvious the refining effect is.
【学位授予单位】：辽宁工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG292
，
本文编号：2270336
[Abstract]:Hypereutectic Al-Si alloys have the advantages of low thermal expansion coefficient, good thermal stability, low density, high hardness, high temperature resistance and wear resistance. For hypereutectic Al-Si alloys, modification is usually used to refine primary silicon. Among the many modification methods, the effect of P modification on refining primary silicon is obvious, stable and easy to carry out. After adding P-containing master alloy into the melt of hypereutectic Al-Si alloy, it is necessary to stir the melt to obtain a better modification effect. However, it is not clear how the degree of stirring affects the modification effect. In this paper, Al-15%Si alloy, Al-18%Si alloy and Al-20%Si alloy are taken as research objects. The modification of Cu-9%P alloy is carried out, and the influence of melt stirring process on modification effect is studied, which provides a theoretical basis for giving full play to the modification of P. The experimental results show that, for Al-20%Si alloy, the more intense the stirring is, the better the refining effect is when the stirring temperature is higher than the melting temperature of Cu-9%P alloy, and with the prolongation of stirring time, The average size of primary silicon decreases first and then increases. When the stirring speed is 224rad / min and the stirring time is 8min, the average size of the primary silicon is refined to 17 渭 m. For Al-15%Si alloy, Al-18%Si alloy and Al-20%Si alloy, when the stirring temperature is below the melting temperature of Cu-9%P alloy, the average size of primary silicon decreases first and then increases with the prolonging of stirring time. The more intense the stirring, the better the refining effect of primary silicon is in the optimum stirring time, the longer the stirring time is, the larger the size of primary silicon is. The best stirring time was not related to the content of Si, but the thinning effect was best when 20min was used, and when the content of 75rad/min), Si was different, the optimum stirring time was different when the 75rad/min), Si content was different. For Al-15%Si alloy, Al-18%Si alloy and Al-20%Si alloy, the average size of primary silicon was refined to 9 渭 m ~ 17 渭 m ~ (12) 渭 m when stirring speed was 224rad / min and stirring time was 20min. The typical eutectic structure disappeared in Al-20%Si alloy, and the higher the content of Si was, the more granular eutectic silicon appeared. The more the average size of primary silicon decreases, the more obvious the refining effect is.
【学位授予单位】：辽宁工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG292
，
本文编号：2270336
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