Grain Refinement and Thermal Stability of 2219 Aluminum Alloy in the Warm Deformation Process
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Grain Refinement and Thermal Stability of 2219 Aluminum Alloy in the Warm Deformation Process Xianchang Mao1,2,3 · Youping Yi1,3 · Shiquan Huang1,3 · Wanfu Guo1,3 · Hailin He4 Received: 15 July 2020 / Accepted: 13 October 2020 © The Korean Institute of Metals and Materials 2020
Abstract 2219 Al alloy is an important material for manufacturing launch vehicles, and its grain structure has a substantial effect on the performance of storage tank transition rings. In this work, warm compression tests (100–350 °C) of 2219 Al alloy were carried out, a grain refinement model of warm deformation was established, and the evolution and thermal stability of the static recrystallized grain size D were analyzed. The results showed that static recrystallization is the main mechanism of grain refinement, and that the nucleation rate and grain refining effects were significantly improved by decreasing the deformation temperatures (T). The established model was found to be accurate, and the predicted and experimental values exhibited high degrees of coincidence. When T and the amount of deformation (Δd) were respectively 150 °C and 70%, the value of D was reduced from 60 μm to 21 μm. Additionally, when the solution treatment time was increased from 0 to 4 h, there was a slight change in the values of D (high thermal stability) when T was lower than 250 °C and Δd was greater than 20%, but they significantly increased when Δd was less than 10%. Keywords 2219 aluminum alloy · Warm deformation · Grain refinement · Static recrystallization · Thermal stability
1 Introduction Because of its high specific strength and fracture toughness, excellent low- and high-temperature mechanical properties, and good stress corrosion resistance and weldability, 2219 aluminum alloy is widely utilized in the aerospace, aviation, navigation, and military fields [1–6]. Currently, 2219 Al alloy is also employed in the development of the transition rings of launch vehicles [6–9]. Generally, the manufacturing process of large rings made of aluminum alloys includes severe plastic deformation processes (hot forging and rolling) and heat-treatment processes. During the manufacturing process, grain refinement is an important means * Hailin He [email protected] 1
College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
2
School of Artificial Intelligence, Hezhou University, Hezhou 542899, China
3
State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083, China
4
Powder Metallurgy Research Institute, Central South University, Changsha 410083, China
by which to improve the mechanical properties of the rings [10–13]. Previous studies have revealed that recrystallization (dynamic or static recrystallization) is the primary way to refine grains [14–18]. However, for 2219 aluminum alloy rings, dynamic recovery is easily initiated during the hot forging and rolling processes (400–520 °C), and dynamic recrystallization may even occur when the deformation reaches the critical strain [7,
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