目的 将异步轧制与电流辅助退火引入到铝锂合金的热机械处理工艺中,以细化晶粒,改善铝锂合金的组织均匀性与力学性能。方法 通过固溶、过时效、异步轧制和电处理四步法,研究异步比和退火方式对晶粒细化的影响,并对其力学性能和充填行为进行测试,对比分析得出异步轧制和电流对晶粒细化的积极作用。结果 异步轧制可以引入剪切应变,随着异步比从1提高到3,电退火90 s后的晶粒尺寸从10.44 μm降低到7.78 μm,织构逐渐弱化,同时形成典型的剪切织构;过时效促使大量粗颗粒析出,在后续的退火过程中可通过颗粒激发形核机制,进而有效促进晶粒细化;当异步比为3时,与传统退火1 800 s时相比,电流辅助退火90 s后晶粒尺寸从9.90 μm降低到7.78 μm,并且更加接近等轴晶;电流的引入提高了再结晶形核率,从而促进了晶粒细化;细化的晶粒可以同时提高材料的强度与塑性,并在表面微结构充填过程中提高晶粒变形均匀性,有效抑制表面裂纹的产生。结论 异步轧制与电流辅助退火的共同作用可有效细化2A97铝锂合金晶粒,改善微观组织均匀性与提高综合力学性能,具有良好的工程应用前景。
Abstract
The work aims to introduce asymmetric rolling and electrically-assisted annealing into the thermomechanical processing of Al-Li alloys for grain refinement, so as to improve microstructural homogeneity and mechanical properties. A four-step process consisting of solution treatment, overaging, asymmetric rolling, and electrically-assisted annealing was applied to investigate the effects of asymmetry ratio and annealing method on grain refinement. Subsequently, the mechanical properties and filling behavior of the alloy were tested. Comparative analysis revealed the distinct positive contributions of both asymmetric rolling and electrically-assisted treatment to grain refinement. Asymmetric rolling introduced shear strain. With asymmetry ratio increasing from 1 to 3, the grain size gradually decreased from 10.44 μm to 7.78 μm, the texture weakened, and the typical shear texture components developed after 90 s of electrically-assisted annealing. Overaging promoted the precipitation of coarse particles, which effectively stimulated nucleation via the particle-stimulated nucleation mechanism. Compared with 1 800 s of conventional annealing, 90 s of electrically-assisted annealing reduced the grain size from 9.90 μm to 7.78 μm when the asymmetry ratio was 3 and promoted a more equiaxed grain morphology. The introduction of the electric current significantly increased the nucleation rate of recrystallization, thereby accelerating grain refinement. The refined grain simultaneously improved strength and plasticity of the alloy. Moreover, it enhanced the uniformity of grain deformation during surface filling, effectively suppressing surface crack formation. The combined use of asymmetric rolling and electrically-assisted annealing effectively refine grains of the 2A97 Al-Li alloy, improve microstructural homogeneity, and enhance overall mechanical properties, showing promising potential for engineering applications.
关键词
铝锂合金 /
电流辅助退火 /
异步轧制 /
颗粒激发形核 /
表面微结构
Key words
Al-Li alloy /
electrically-assisted annealing /
asymmetric rolling /
particles stimulated nucleation /
surface texture
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