高强7050铝合金超低温大变形加工与组织、性能调控

发布时间：2018-06-26 20:40

本文选题：高强铝合金 + 超低温变形　；参考：《金属学报》2017年09期

【摘要】：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。
[Abstract]:The low temperature plastic deformation of high strength 7050 aluminum alloy and its effect on microstructure and properties were studied by means of low temperature cooling rolling deformation. The results show that the high strength 7050 aluminum alloy can achieve higher rolling deformation rate than that of warm / hot rolling phase after pretreatment with liquid nitrogen, and produce a large number of substructure and high density dislocations, which make the alloy strengthened significantly. The high deformation capacity at low temperature is mainly related to the high work hardening ability of the alloy at low temperature, while the enhancement of strength comes mainly from the contribution of solid solution strengthening and deformation dislocation strengthening. Although the aging process of quenched high-strength 7050 aluminum alloy can be accelerated obviously by ultra-low temperature deformation, direct aging treatment can make 7050 aluminum alloy keep higher strength and certain elongation, in which precipitation and dislocation strengthening are the main causes of strengthening. The precipitation of recovery and strengthening phase induced by aging promotes the improvement of elongation. During the deformation of quenched high strength 7050 aluminum alloy at room temperature, the deformation heat results in the interaction between solute cluster (or GP region) and 畏 'phase in the matrix and the deformation dislocation, resulting in a large number of shear bands (instability zone). It is easy to lead to cracking or edge crack of rolling plate, and the solute diffusion is blocked during ultra-low temperature deformation, so that the precipitation of strengthening phase is restrained, which obviously reduces the occurrence of shear instability zone and makes the alloy uniform. Stable plastic deformation or good work hardening to ensure high quality ultra-low-temperature rolling 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 deformation resistance of high strength aluminum alloy.
【作者单位】：北京科技大学新金属材料国家重点实验室;北京科技大学冶金与生态工程学院;
【基金】：国家自然科学基金项目No.51401016 中央高校基本科研业务费专项资金项目No.FRF-TP-12-137A 现代交通金属材料与加工技术北京实验室项目新金属材料国家重点实验室基金项目No.2011Z-05~~
【分类号】：TG146.21

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