触变模锻Al-7%Si/Al-30%Si合金双金属的数值模拟

Numerical simulation of thixo-forging Al-7%Si/Al-30%Si alloys bimetal

采用有限元软件DEFORM-3D对半固态模锻Al-7%Si/Al-30%Si(质量分数,下同)合金复合材料过程进行数值模拟,研究复合成形过程双金属坯料的充型特征,同时探讨工艺参数对复合成形的影响规律。模拟结果表明:单金属触变模锻具有整体性变形特征,双金属触变模锻充型性能受界面传力影响,其非动模侧充型能力比单金属的弱;随着下坯料初始温度提高,界面传力增强,底部充型能力增强;下坯料初始温度过高,会导致复合界面偏靠下侧、弯曲程度大、底部出现飞边;坯料与模具之间的摩擦因素越大,复合界面弯曲和边部向上倾斜越严重;Al-7%Si和Al-30%Si合金初始温度分别为585℃和575℃,当坯料与模具之间摩擦因数较小时,上、下坯料变形协调,锻件充型饱满,复合界面水平居中,双金属模锻复合效果良好。

The forming process of thixo-forging Al-7%Si/Al-30%Si alloy composite in the semi-solid state was simulated by finite element software DEFORM-3D.The filling characteristics of bimetal billets in the composite forming process and the effects of process parameters on composite forming were investigated. The results show that single metal thixo-forging has integrity forming feature. And the filling capacity of bimetal thixo-forging is greatly affected by the efficiency of the stress transfer through interface, which results in the fact that the filling capacity of the bottom billet on the opposite side of moving die is worse than that of the single metal. The filling capacity of bottom billet would improve with the increase of the initial temperature of bottom billet or the efficiency of the stress transfer. However, when the initial temperature of the bottom billet is too high, the interface will deviate to bottom die and bend badly, and flash will appear on the bottom. The greater the friction coefficient between billets and molds, the more serious the composite interface bends and edge tilts upward. When the initial temperatures of Al-7%Si alloy and Al-30%Si alloy are 585 ℃ and575 ℃, respectively, and the friction coefficients between billets and dies are small, top and bottom billets are deformed harmonically, forged pieces fill fully, interface of composite is well located in the center of the work pieces. The filling character is good.