Bate Casey, King Philip, Sim Jay, Manogharan Guha
Department of Mechanical Engineering, Penn State University, State College, PA 16801, USA.
Materials (Basel). 2023 Jan 12;16(2):756. doi: 10.3390/ma16020756.
Turbulent filling of molten metal in sand-casting leads to bi-films, porosity and oxide inclusions which results in poor mechanical properties and high scrap rate of sand castings. Hence, it is critical to understand the metal flow in sand-molds, i.e., casting hydrodynamics to eliminate casting defects. While multiple numerical methods have been applied to simulate this phenomenon for decades, harsh foundry environments and expensive x-ray equipment have limited experimental approaches to accurately visualize metal flow in sand molds. In this paper, a novel approach to solve this challenge is proposed using Succinonitrile (SCN) as a more accurate metal analog in place of water. SCN has a long history in solidification research due to its BCC (Body-Centered-Cubic) crystal structure and dendrite-like solidification (melting temperature ~60 °C) like molten aluminum. However, this is the first reported study on applying SCN through novel casting hydrodynamics to accurately visualize melt flow for casting studies. This paper used numerical simulations and experiments using both water and SCN to identify the critical dimensionless numbers to perform accurate metal flow analog testing. Froude's number and wall roughness were identified as critical variables. Experimental results show that SCN flow testing was more accurate in recreating the flow profile of molten aluminum, thus validating its utility as a metal analog for metal flow research. Findings from this study can be used in future metal flow analysis such as: runner, in-gate and integrated filling-feeding-solidification studies.
砂型铸造中熔融金属的紊流充型会导致双膜、气孔和氧化物夹杂，从而使砂型铸件的力学性能较差且废品率较高。因此，了解砂型中的金属流动，即铸造流体动力学以消除铸造缺陷至关重要。尽管几十年来已经应用了多种数值方法来模拟这一现象，但恶劣的铸造环境和昂贵的X射线设备限制了准确可视化砂型中金属流动的实验方法。本文提出了一种新颖的方法来应对这一挑战，即使用丁二腈（SCN）作为更精确的金属模拟物来替代水。由于其体心立方（BCC）晶体结构以及类似树枝状的凝固方式（熔化温度约60°C），与熔融铝相似，SCN在凝固研究中有着悠久的历史。然而，这是首次报道通过新颖的铸造流体动力学应用SCN来准确可视化铸件研究中的熔体流动的研究。本文使用数值模拟以及水和SCN的实验来确定进行准确金属流动模拟测试的关键无量纲数。弗劳德数和壁面粗糙度被确定为关键变量。实验结果表明，SCN流动测试在重现熔融铝的流动剖面方面更为准确，从而验证了其作为金属流动研究的金属模拟物的效用。本研究的结果可用于未来的金属流动分析，如：流道、内浇口以及综合充型-补缩-凝固研究。
