铝合金铸件定向凝固过程的数值模拟
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摘要
为了研究铝合金定向凝固组织的变化规律,采用有限元软件ProCAST对Al-Si-Cu合金定向凝固过程进行模拟,分析了不同浇注温度和抽拉速率对铸件定向凝固过程中的温度梯度、固液界面前沿、糊状区宽度、枝晶生长速率和二次枝晶臂间距的影响。结果表明,当浇注温度越高时,温度梯度越大,而固液界面前沿下凹越小,糊状区宽度也越窄,从而越有利于顺序凝固的发生;随着抽拉速率的增大,枝晶生长速率先增大后减小,当抽拉速率为200μm/s时,最大生长速度达到0.093mm/s,铸件凝固组织最佳;当抽拉速率大于300或小于200μm/s时,都会导致枝晶生长速率缓慢,枝晶生长不平稳,二次枝晶臂粗大。对模拟得到较优的工艺参数进行试验验证,可以制备出具有较好力学性能的铸件。
In order to study the change rule of directional solidification microstructure of aluminum alloy,the directional solidification process of Al-Si-Cu aluminum alloy was simulated with the finite element simulation software ProCAST.The effects of different pouring temperature and pulling rate on the temperature gradient,solid-liquid interface front,the width of the mushy zone,dendritic growth rate and secondary dendritic arm spacing during directional solidification of castings were simulated and analyzed.The results showed that the higher the pouring temperature,the greater the temperature gradient,and the smaller the concave at the front of the solid-liquid interface,the narrower the width of the mushy zone.Which was more favorable for sequential solidification.With the increase of pulling rate,the dendritic growth rate first increased and then decreased.When the pulling rate was 200μm/s and the maximum dendritic growth rate was 0.093 mm/s,the solidification structure of the casting was the best.When the pulling rate was greater than 300μm/s or less than 200μm/s,the dendritic growth rate would be slow,the dendritic growth would not be stable,and the secondary dendritic arm would be coarse.The better process parameters obtained by simulation were verified by testing,which could be used to prepare castings with better mechanical properties.
In order to study the change rule of directional solidification microstructure of aluminum alloy,the directional solidification process of Al-Si-Cu aluminum alloy was simulated with the finite element simulation software ProCAST.The effects of different pouring temperature and pulling rate on the temperature gradient,solid-liquid interface front,the width of the mushy zone,dendritic growth rate and secondary dendritic arm spacing during directional solidification of castings were simulated and analyzed.The results showed that the higher the pouring temperature,the greater the temperature gradient,and the smaller the concave at the front of the solid-liquid interface,the narrower the width of the mushy zone.Which was more favorable for sequential solidification.With the increase of pulling rate,the dendritic growth rate first increased and then decreased.When the pulling rate was 200μm/s and the maximum dendritic growth rate was 0.093 mm/s,the solidification structure of the casting was the best.When the pulling rate was greater than 300μm/s or less than 200μm/s,the dendritic growth rate would be slow,the dendritic growth would not be stable,and the secondary dendritic arm would be coarse.The better process parameters obtained by simulation were verified by testing,which could be used to prepare castings with better mechanical properties.
引文
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[19]胡鹏,李军,李建国.基于ProCast的镍基单晶高温合金数值模拟[J].热加工工艺,2018,47(1):117.
[20]唐宁,张航,许庆彦,等.空心叶片LMC定向凝固温度场和微观组织模拟[J].特种铸造及有色合金,2014,34(6):561.
[21]王永锋,孟祥斌,李金国,等.定向凝固工艺对高温合金DZ417G变截面疏松形成的影响[J].稀有金属材料与工程,2016,45(5):1264.
[22]李新雷,夏瑾,郝启堂.离心真空吸铸成形叶轮件凝固组织与性能研究[J].稀有金属材料与工程,2018,47(4):1319.
[23]朱权利,吴资湧,夏勇,等.挤压铸造ZA27蜗轮的力学性能及摩擦磨损性能[J].特种铸造及有色合金,2014,34(10):1116.
[2]王泽鹏,肖鹏程,朱立光,等.方坯连铸结晶器铜管温度场分析[J].钢铁,2018,53(3):38.
[3]张兴中,任素波,周超,等.新型结晶器内流场及温度场数值模拟[J].钢铁,2015,50(9):53.
[4]刘志远,王重君,蔡兆镇,等.含铌微合金钢连铸坯角部裂纹控制二冷新工艺[J].中国冶金,2018,28(3):22.
[5]孔令坤.数值模拟在极限规格H型钢工艺优化中的应用[J].中国冶金,2017,27(4):21.
[6]何方,杨西鹏,贾贵兴,等.邯钢罩式退火生产Ti-IF钢工艺[J].中国冶金,2017,27(1):36.
[7]余万华,刘新忠,戴石峰,等.加热钢坯内部温度的计算机模拟[J].轧钢,2005,22(5):17.
[8]康慧君,李金玲,王同敏,等.定向凝固Al-Mn-Be合金初生金属间化合物相生长行为及力学性能[J].金属学报,2018,54(5):809.
[9] LI Chong-he,WEI Chao,ZHANG Ru-lin,et al.Effects of directional solidification parameters and crystal selector on microstructure of single crystal of Ni-base superalloys[J].Journal of Central South University,2018,25(1):1.
[10]李岩,王天浩,张黎伟,等.凝固模式对定向凝固TiAl-Nb合金组织和力学性能影响[J].精密成形工程,2018,10(3):6.
[11] Elliott A J,Pollock T M.Thermal analysis of the bridgman and liquid-metal-cooled directional solidification investment casting processes[J].Metallurgical and Materials Transactions A,2007,38(4):871.
[12] Miller J D,Yuan L,Lee P D,et al.Simulation of diffusion-limited lateral growth of dendrites during solidification via liquid metal cooling[J].Acta Materialia,2014,69(5):47.
[13]杨亮,李嘉荣,金海鹏,等.DD6单晶精铸薄壁试样定向凝固过程数值模拟[J].材料工程,2014(11):15.
[14]卢玉章,申健,郑伟,等.单晶铸件凝固过程工艺优化的数值模拟[J].材料工程,2016,44(11):1.
[15]司乃潮,史剑,司松海,等.晶体生长速率对定向凝固Al-4.5%Cu合金一次枝晶间距的影响[J].铸造,2010,59(11):1172.
[16]李传涛,玄伟东,刘欢,等.单晶高温合金杂晶形成倾向性数值模拟[J].上海金属,2017,39(3):51.
[17] Brundidge C L,Miller J D,Pollock T M.Development of dendritic structure in the liquid-metal-cooled,directional-solidification process[J].Metallurgical and Materials Transactions A,2011,42(9):2723.
[18]郭如峰,刘林,李亚峰,等.液态金属冷却法制备DD403合金过程温度场和晶粒组织的数值模拟[J].铸造,2014,63(2):145.
[19]胡鹏,李军,李建国.基于ProCast的镍基单晶高温合金数值模拟[J].热加工工艺,2018,47(1):117.
[20]唐宁,张航,许庆彦,等.空心叶片LMC定向凝固温度场和微观组织模拟[J].特种铸造及有色合金,2014,34(6):561.
[21]王永锋,孟祥斌,李金国,等.定向凝固工艺对高温合金DZ417G变截面疏松形成的影响[J].稀有金属材料与工程,2016,45(5):1264.
[22]李新雷,夏瑾,郝启堂.离心真空吸铸成形叶轮件凝固组织与性能研究[J].稀有金属材料与工程,2018,47(4):1319.
[23]朱权利,吴资湧,夏勇,等.挤压铸造ZA27蜗轮的力学性能及摩擦磨损性能[J].特种铸造及有色合金,2014,34(10):1116.
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