2060铝锂合金热冲压成形本构模型及应用

Constitutive Model and Application of 2060 Aluminum-Lithium Alloy in Hot Stamping Process

摘要:

2060合金作为第三代铝锂合金，与传统铝合金相比质量更轻，与前几代铝锂合金相比机械性能更优越。通过热拉伸实验和模型分析研究了2060铝锂合金板材的热变形行为。通过扫描电子显微镜观察断裂形态，建立宏观力学行为和微观组织演变相结合的本构模型。最后，将建立的本构模型嵌入有限元模拟软件中，分析了2060铝锂合金的变形过程。结果表明，峰值应力随着温度的升高和应变速率的降低而降低，变形温度对2060铝锂合金的各向异性有显著影响；在400 ℃或更高的温度下可以消除板料各向异性；本构模型准确预测了真实应力-真实应变曲线的变化和微观结构的演变；通过断口形貌分析发现，2060铝锂合金断裂形式为典型的韧性断裂，断口处出现的峰脊促进了板料在高温下的变形。仿真结果与热冲压条件下的实验测试结果具有较好的一致性。

Abstract:

2060 alloy, as the third generation aluminum-lithium (Al-Li) alloy, has lighter mass than traditional aluminum alloys and superior mechanical properties compared with previous generations of Al-Li alloy. The hot deformation behavior of 2060 Al-Li alloy sheets were investigated by hot tensile tests and model analysis. The fracture morphology was observed by scanning electron microscope. Then, the constitutive model coupled with the macroscopic mechanical behavior and the microstructure evolution was established. Finally, the established constitutive model was embedded in the finite element simulation software to analyze the deformation process of 2060 Al-Li alloy. The results show that the peak stress decreases with the increase in temperature and the decrease in strain rate. The deformation temperature has a significant impact on the anisotropy of the 2060 Al-Li alloy. It can be considered that the anisotropy can be eliminated at 400 °C or higher temperatures. It is found that the fracture process of 2060 Al-Li alloy conforms to typical ductile fracture laws. The presence of ridge improves the sheet deformation at elevated temperature. The constitutive model can predict the change of the true stress-true strain curves and the microstructure evolution accurately. The simulation results have good agreement with the experimental tests under hot stamping conditions.