2196铝锂合金热变形与挤压型材晶粒控制研究

Thermal Deformation and Grain Control of Extruded Profile for 2196 Al-Li Alloy

摘要:

研究了2196铝锂合金热压缩变形流变行为和晶粒组织演变规律，基于挤压模拟与型材工程化试制，实现了典型“工”字薄壁型材晶粒组织调控。结果表明，合金在较宽的变形参数范围内具有良好的热塑性变形能力，动态回复是晶粒组织演变的主要机制；在较低温度（350、400 ℃）和较高应变速率（10 s^-1）耦合条件下，应变集中导致少量的局部动态再结晶。挤压过程中大应变促进了再结晶形成，型材截面上变形条件差异导致了晶粒组织不均匀性。结合装备条件提出，当挤压温度为430 ℃及截面应变速率为0.005~0.95 s^-1时，能够获得相对均匀的晶粒组织，且保持了较低的再结晶程度和丰富的亚晶结构，为实现型材强韧性匹配提供了研究基础。

Abstract:

Flow behavior and grain structure evolution were studied for 2196 aluminum-lithium alloy during hot compression deformation. Based on extrusion simulation and profile trial production, grain structure control of typical I-shaped thin-walled profiles was achieved. The results show that the alloy exhibits excellent hot deformability in a relatively wide parameter range. The dominate mechanism of microstructure evolution is dynamic recovery, although some localized dynamic recrystallization is also observed. At lower temperatures (350, 400 ℃) and higher strain rates (10 s^-1), strain concentration leads to a small amount of local dynamic recrystallization. Compared to experimental compression deformation, the larger strain of extrusion process promotes the formation of dynamic recrystallization. The differences of deformation conditions on profile section lead to non-homogeneous grain structure. Based on the equipment capability, relatively uniform microstructure be obtained under deformation conditions of 430 ℃ and strain rate of 0.005–0.95 s^-1 on profile section, while maintaining lower fraction of recrystallization and abundant sub-grain structure, which is benefit for the strength and toughness matching.