Characterization of Tensile Properties, Limiting Strains, and Deep Drawing Behavior of AA5754-H22 Sheet at Elevated Temperature
Characterization of Tensile Properties, Limiting Strains, and Deep Drawing Behavior of AA5754-H22 Sheet at Elevated Temperature
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DOI：
10.1007/s11665-015-1740-6
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发表时间：
2015-10
影响因子：
2.3
通讯作者：
Sudhy S. Panicker;H. Singh;S. Panda;R. Dashwood
中科院分区：
文献类型：
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作者：
Sudhy S. Panicker;H. Singh;S. Panda;R. Dashwood
汽车工业在设计用于通过温成形技术制造汽车覆盖件的工具、加热系统和加工顺序之前，非常感兴趣的是表征铝合金在高温下的可成形性改善。采用Cowper-Symonds本构方程对AA 5754-H22铝合金在5种不同温度和3种不同应变速率下的拉伸行为进行了研究。设计和制造了实验室规模的温成形设备，进行极限圆顶高度和深冲压试验，以评估成形极限应变和金属板在不同的工具温度下的冲压性能。当模具和冲头都加热到200 °C时，成形极限应变和圆顶高度显著提高。当模具和冲头温度分别保持在200 ° C和30 °C时，观察到深冲杯深度的显著改善，从而在从凸缘到中心的坯料上产生约93 °C的非等温温度梯度。采用Barlat-89屈服准则中的温度相关特性与Cowper-Symonds硬化模型相结合的热力耦合有限元模型，成功地预测了不同等温和非等温条件下的成形行为，并以实验极限应变为损伤模型，验证了变形杯形件的减薄/失效位置。
Automotive industries are very much interested in characterization of formability improvement of aluminum alloys at elevated temperatures before designing tools, heating systems, and processing sequences for fabrication of auto-body panels by warm forming technology. In this study, tensile tests of AA5754-H22 aluminum alloy were carried out at five different temperatures and three different strain rates to investigate the deformation behavior correlating with Cowper-Symonds constitutive equation. Laboratory scale warm forming facilities were designed and fabricated to perform limiting dome height and deep drawing tests to evaluate forming limit strains and drawability of sheet metal at different tool temperatures. The forming limit strain and dome height improved significantly when both the die and punch were heated to 200 °C. Remarkable improvement in deep drawn cup depth was observed when die and punch temperatures were maintained at 200 and 30 °C, respectively, producing a non-isothermal temperature gradient of approximately 93 °C across the blank from flange to center. The forming behavior at different isothermal and non-isothermal conditions were predicted successfully using a thermo-mechanical FE model incorporating temperature-dependent properties in Barlat-89 yield criterion coupled with Cowper-Symonds hardening model, and the thinning/failure location in deformed cups were validated implementing the experimental limiting strains as damage model.