Abstract The hardening behavior of heat treatable alloys during deformation is attributed to three mechanisms of forest dislocations, solid solution and precipitation hardening which hinder the motion of dislocations and increase the density of statistically stored dislocation. In this paper, a model for the flow stress of a 2024 heat treatable aluminum alloy during plastic deformation is developed combining the superposition of these three hardening mechanisms. This model was then implemented into the finite element model in order to evaluate the evolution of the flow stress of 2024 aluminum alloy during multi-directional forging (MDF). Subsequently, an equation is developed for evaluating the material strength changes during natural aging after MDF. The experimental results from compression and hardness tests show a good agreement between modeling and experimental data. The results show that the flow stress is increased about 90% after the first pass of MDF and then increased just about 2% after the second pass. Through natural aging process, the hardening rate is higher in non-deformed samples and is decreased with increasing the aging time.

中文翻译：

---

2024铝合金多向锻造过程中的流动应力及塑性变形后的自然时效

摘要 可热处理合金在变形过程中的硬化行为归因于森林位错、固溶和沉淀硬化三种机制，它们阻碍了位错的运动并增加了统计存储位错的密度。在本文中，结合这三种硬化机制的叠加，开发了塑性变形过程中 2024 可热处理铝合金的流动应力模型。然后将该模型应用到有限元模型中，以评估 2024 铝合金在多向锻造 (MDF) 过程中的流动应力演变。随后，开发了用于评估 MDF 后自然时效期间材料强度变化的方程。压缩和硬度测试的实验结果表明建模和实验数据之间具有良好的一致性。结果表明，中密度纤维板第一次通过后流动应力增加了约 90%，然后在第二次通过后仅增加了约 2%。通过自然时效过程，未变形样品的硬化率较高，并随着时效时间的增加而降低。