Al-Mg-Si系铝合金是一种热处理强化合金。研究Al-Mg-Si系铝合金的抗冲击性能对拓展其在工程中的应用具有重要意义。以6082-T6铝合金为具体研究对象,使用分离式霍普金森压杆(SHPB)装置,研究了材料在不同温度和平均应变率下的动态力学响应,确定了材料在极端条件下的使用性能。引入绝对温度升来优化现有的本构模型。结果表明,在高速冲击下,环境温度为298.15~473.15K时,材料的内部热软化效应在与加工硬化的竞争中占主导地位,导致材料的流动应力降低。通过对真实应力-应变曲线的分析,发现材料的弹性模量与应变率呈负相关,与温度负相关,并表现出明显的温度软化效应。屈服强度与温度呈负相关,与应变速率呈正相关,表现出明显的应变速率硬化效应。基于SEM显微分析,发现在给定的条件下,一些样品出现绝热剪切带,它们的内部结构表现出明显的变化。据判断,当高速冲击发生时,在剪切带处诱发裂纹,裂纹将继续沿着绝热剪切带发展,导致许多斜裂纹,这些裂纹会逐渐变大,最终导致材料失效。最后,基于模型,改善了应变速率和温度软化项,并引入了绝热温升的上升。改进后的模型能更好地描述材料的应变率效应,准确地描述其流动应力。为材料的工程应用提供了理论依据。
Al-Mg-Si series aluminum alloy is a heat-treatment-strengthened alloy. Research on the impact resistance of Al-Mg-Si series aluminum alloy is of great significance to expand its application in engineering. Taking 6082-T6 aluminum alloy as the concrete research object, using the split Hopkinson pressure bar (
SHPB) device, the dynamic mechanical response of the material under different temperatures and average strain rates was studied, and the service performance of the material under extreme conditions was determined. The absolute temperature rise was introduced to optimize the existing constitutive model. The results show that when the environment temperature is 298.15~473.15 K under high-speed impact, the internal thermal softening effect of the material is dominant in the competition with the work hardening, resulting in a decrease in the flow stress of the material. Through the analysis of the real stress-strain curve, it was found that the elastic modulus of the material was negatively correlated with the strain rate, negatively correlated with the temperature, and showed an obvious temperature-softening effect. Yield strength was negatively correlated with temperature and positively correlated with strain rate, which showed an obvious strain rate hardening effect. Based on SEM microscopic analysis, it was found that under given conditions, adiabatic shear bands appeared in some samples, and their internal structures demonstrated obvious change. It was judged that when high-speed impact occurs, cracks are induced at the shear bands, and the cracks will continue to develop along the adiabatic shear bands, resulting in many oblique cracks which will gradually become larger and eventually lead to material failure. Finally, based on the model, the strain rate and temperature softening terms were improved, and a rise in adiabatic temperature rise was introduced. The improved model can better describe the strain rate effect of the material and accurately describe its flow stress. It provides a theoretical basis for the engineering application of materials.