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通过低温冷却+轧制变形的方法研究了高强7050铝合金的低温塑性变形及其对合金组织性能的影响。结果表明,高强7050铝合金经液氮冷却预处理后可实现与温/热轧相比较高的轧制变形加工量,并产生大量亚结构和高密度位错,使合金显著强化,其中低温下的高变形能力主要与合金在低温下具有高的加工硬化能力密切相关,而强度提升主要来自于固溶强化和变形位错强化的贡献。虽然超低温变形能够明显加快淬火态高强7050铝合金的时效进程,但直接时效处理可使超低温变形态7050铝合金保有较高的强度和一定延伸率,其中析出和位错强化是其强化主因,而时效引起的回复和强化相析出共同促进延伸率的改善。淬火态高强7050铝合金在室温变形过程中,形变热引起基体中析出的溶质原子团簇(或GP区)和η′相与变形位错发生交互作用,导致大量剪切带(失稳区)形成,从而易引发轧板开裂或边裂,而超低温变形过程中溶质扩散受阻以致强化相析出被抑制,从而明显降低了剪切失稳区的发生,使合金能够获得均匀、稳定的塑性变形或良好的加工硬化,确保获得较高质量的超低温轧板。高强铝合金在低温下所表现出来的优异塑性变形和加工能力有望成为改善高强铝合金难变形加工的有效途径。
The low temperature plastic deformation of high strength 7050 aluminum alloy and its effect on the microstructure and properties of the alloy were studied by means of low temperature cooling + rolling deformation. The results show that the high-strength 7050 aluminum alloy can be pre-treated by liquid nitrogen cooling to achieve high rolling deformation compared with that of hot / hot rolling, and produce a large amount of sub-structures and high-density dislocations to significantly strengthen the alloy. The high deformation capacity is mainly related to the high work-hardening ability of the alloy at low temperature, while the strength improvement mainly comes from the contribution of solid solution strengthening and deformation dislocation strengthening. Although the ultra-low temperature deformation can significantly accelerate the aging process of quenched high strength 7050 aluminum alloy, the direct aging treatment can maintain the ultra-low temperature deformation state 7050 aluminum alloy with higher strength and a certain elongation, of which precipitation and dislocation strengthening is its main reinforcement, and Aging caused by the reply and strengthen the precipitation phase together to promote the improvement of elongation. Quenching high strength 7050 aluminum alloy during deformation at room temperature, deformation caused by the heat of the matrix solute atomic clusters (or GP area) and η ’phase and deformation dislocation interaction occurs, resulting in a large number of shear zone (destabilization zone) formation , Which easily lead to cracking or edge cracking, and ultra-low temperature deformation during the solute diffusion obstruction to strengthen the phase precipitation is inhibited, thus significantly reducing the occurrence of shear instability zone, the alloy can be uniform, stable plastic deformation or good The work hardening, to ensure access to high quality ultra-low temperature rolled plate. The excellent plastic deformation and processing ability of high strength aluminum alloy at low temperature is expected to be an effective way to improve the hard deformation of high strength aluminum alloy.