A dislocation density-based model considering dynamic strain aging for annealed and water-quenched aluminum alloys under low-temperature conditions

Low-temperature forming is a novel manufacturing method for aluminum alloy components. To better understand the flow characteristics and deformation behavior of aluminum alloys at low temperatures, uniaxial tensile tests were conducted with an initial strain rate range of 2.5 × 10−4–1 × 10−2 s−1 and a temperature range of 77–298 K for annealed (O) and water-quenched (WQ) 2060 Al–Cu–Li alloys. The results showed that the two tempered alloys exhibited excellent work hardening at lower temperatures, resulting in improved ductility, especially in the WQ-tempered alloy. Dynamic strain aging (DSA) caused by interactions between solute atoms and moving dislocations occurred at higher temperatures and lower strain rates, which resulted in serrated flow. Because moving dislocations were additionally pinned by solute clusters, the flow stress increased. The stress increase and negative strain rate caused by DSA could not be captured using the typical dislocation density-based K-M model. Thus, a modified K-M model that considered DSA was proposed to describe the tensile behavior of the studied alloys, and the stress-strain values predicted by the proposed model agreed well with the experimental ones.