不同热处理状态的2219铝合金动态加载下力学行为和断裂机制研究

Study on mechanical behavior and fracture mechanism of 2219 aluminum alloy with different heat treatment conditions under dynamic loading

摘要:

本文通过分离式霍普金森拉杆实验，研究了不同热处理状态的2219铝合金在动态加载下的力学行为和断裂机制。结果表明：2219-T6和2219-T4的抗拉强度和应变率敏感性随着应变率的增加而增加，而2219-O的则先增加后减小，且2219铝合金的应变率敏感性和应变硬化率随着应变的增加而减小；在动态加载下，材料在较高的应力集中程度下形成了局部的解理及第二相颗粒碎裂的形貌，且在较高应变率(≥650 s-1)下，随着应变率的增加，应力集中程度更高，解理形貌的占比也越大，同时由于材料在裂纹扩展的同时依旧可以发生一定量的变形，使得材料整体在较高应变率(≥650 s-1)下具有更高的成形极限，也导致材料在较高的加工硬化下形成具有低塑性特征的断口。

Abstract:

In this paper, the mechanical response and fracture mechanism of 2219 aluminum alloy with different heat treatment conditions under dynamic loading were studied by means of split Hopkinson tension bar experiment. The results show that: The tensile strength and strain rate sensitivity of 2219-T6 and 2219-T4 increase with the increase of strain rate, while that of 2219-O increases first and then decreases. And the strain rate sensitivity and strain hardening rate of 2219 aluminum alloy decrease with the increase of strain; Under the dynamic loading conditions, the material forms the partial dissociation morphology and the morphology of the second phase particle break under the higher stress concentration degree, and at higher strain rate (≥650 s-1), with the increase of strain rate, the stress concentration degree becomes higher, and the proportion of dissociation morphology becomes larger. At the same time due to the material can still undergo a certain amount of deformation at the same time of crack propagation, the material as a whole has a higher forming limit under the higher strain rate (≥650 s-1), it also leads to the formation of fracture morphology with low plasticity under the action of higher work hardening.