Metals and Materials International ( IF 3.3 ) Pub Date : 2021-09-16 , DOI: 10.1007/s12540-021-01048-w Deepak Patel 1 , Prasenjit Biswas 1 , Sanjeev Das 1 , Anil Kumar 2 , Hiren R. Kotadia 3 , Archana Mallik 4
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The present investigation focuses on grain refinement in pure aluminum and its alloy under mechanical stirring with a very low degree of forced convection of 800 rpm as compared to reported values of up to 8000 rpm during direct chill casting process (DC). Commercially pure aluminum (99.7%) and Al6082 alloy billets were fabricated in an in-house designed DC casting simulator. Mechanical forced convection (MFC) was applied to the melt during casting by a common four-bladed impeller. The microstructural properties of the as-cast billets have been analysed to study the effect of MFC during casting and solidification. The structure of both Al and its alloy is found to be refined in presence of MFC as compared to conventional DC. A combination of simulation, experimental and theoretical approaches has been used to determine the effect of MFC in melt-temperature distribution to propose the mechanism of grain refinement. It has been observed that MFC prominently reduces the temperature gradient and extends undercooling time, resulting in fine grain structure.
Graphic abstract
中文翻译：
低强度机械强制对流下铝及其合金直接冷铸晶粒细化机理的预测
本研究的重点是纯铝及其合金在机械搅拌下的晶粒细化，与直接冷硬铸造过程 (DC) 期间高达 8000 rpm 的报告值相比，800 rpm 的强制对流程度非常低。商用纯铝 (99.7%) 和 Al6082 合金坯料是在内部设计的直流铸造模拟器中制造的。机械强制对流 (MFC) 在铸造过程中通过普通的四叶叶轮应用于熔体。分析了铸态钢坯的显微组织特性，以研究 MFC 在铸造和凝固过程中的影响。与传统的 DC 相比，Al 及其合金的结构在 MFC 的存在下都得到了改善。模拟组合，实验和理论方法已被用于确定 MFC 对熔体温度分布的影响，以提出晶粒细化的机制。据观察，MFC 显着降低了温度梯度并延长了过冷时间，从而产生了细晶粒结构。
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