Abstract

Cryogenic forming, a new technology used to manufacture aluminum alloy thin-walled parts, has attracted much attention in recent years. This work presents an experimental and theoretical study of 2024-O aluminum alloy sheet forming limit at cryogenic temperatures and provides an effective method for accurate prediction of forming limit curves (FLCs) at cryogenic temperatures. Uniaxial tensile experiments at different temperatures were carried out between 20 °C and − 196 °C to obtain the constitutive equation of the material at cryogenic temperatures. The Marciniak–Kuczynski (M–K) model was used to predict FLCs at cryogenic and room temperatures. The constitutive equation and yield functions are used in the model. The effects of different yield criteria (Mises, Hill-48, Barlat89, Gotoh, and Yld2000-2d) on the prediction results of FLC are analyzed. These prediction results were verified by the Nakazima test, and it was found that the Yld2000-2d yield criterion is the most accurate for FLC prediction. Finally, the M–K model is combined with this criterion to predict the FLC at different temperatures. It was found that the lower the temperature, the higher the FLC curve and the better the sheet formability, and the increase is more obvious at extremely low temperatures.

Graphic Abstract

中文翻译：

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低温下2024-O铝合金薄板成形极限的实验和理论研究

摘要

低温成形是用于制造铝合金薄壁零件的一种新技术，近年来受到了广泛的关注。这项工作提出了在低温下2024-O铝合金板材成形极限的实验和理论研究，并为准确预测在低温下成形极限曲线（FLC）提供了有效的方法。在20°C至-196°C的温度范围内进行了单轴拉伸实验，得出了材料在低温下的本构方程。Marciniak-Kuczynski（M-K）模型用于预测低温和室温下的FLC。模型中使用本构方程和屈服函数。分析了不同产量标准（Mises，Hill-48，Barlat89，Gotoh和Yld2000-2d）对FLC预测结果的影响。通过Nakazima试验验证了这些预测结果，发现Yld2000-2d屈服准则对于FLC预测最准确。最后，将M–K模型与该标准组合以预测不同温度下的FLC。发现温度越低，FLC曲线越高，片材的可成型性越好，并且在极低的温度下这种增加更为明显。

图形摘要