An investigation of cryogenic-aging process attemptted to alleviate mechanical anisotropy of 7055 thick plate
An investigation of cryogenic-aging process attemptted to alleviate mechanical anisotropy of 7055 thick plate
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DOI：
10.1016/j.msea.2021.142589
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发表时间：
2021-12
期刊：
影响因子：
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通讯作者：
Tao Wang;F. Guo;K. Matsuda;Y. Zou
中科院分区：
文献类型：
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作者：
Tao Wang;F. Guo;K. Matsuda;Y. Zou
考虑到深冷处理技术在航空航天制造领域的应用，为解决7055铝锌镁铜合金厚板的力学各向异性问题，选择了该合金厚板作为研究对象。采用深冷处理、预变形和自然时效作为预处理，两级人工时效作为终处理，采用多种低温时效工艺。本文优化的人工时效工艺参数为110 °C/6 h + 130 °C/16 h，获得了最佳的横向时效性能（Rm-max= 668 Mpa，Rp0.2-max= 635 Mpa，A25 mm-max = 8.52%）。几乎所有经过不同深冷预处理的试样都获得了稳定的塑性变形能力。在低温时效过程的不同阶段，一般存在不同程度的几何再结晶、连续再结晶和不连续再结晶。最终的形态是源于低温或自然时效析出物的钉扎效应与源于低温或预拉伸变形组织中储存的能量的再结晶驱动力之间相互妥协的结果。对于热轧AA 7055厚板，通过深冷处理或横向压缩变形，可以强化原轧制黄铜对。但由于不同方向的回复和不连续再结晶能力不同，最终的织构和形貌主要受人工阶段的影响。拉伸塑性变形和循环深冷处理可以更有效地破坏黄铜零件，以及连续的直的几何必要边界。由于预处理可能会加速沉淀析出，因此人工时效时间的修改具有良好的前景，以获得更优异的机械性能。
Considering the application of cryogenic treatment in aerospace manufacturing field, the hot rolled 7055 Al–Zn–Mg–Cu alloy thick plate was selected in order to solve its mechanical anisotropy. Several cryogenic-aging processes were applied by introducing deep cryogenic treatment, pre-deformation and natural aging as pre-treatments and two-stage artificial aging as final treatment. An optimized artificial aging parameter in this paper is 110 °C/6 h + 130 °C/16 h, for a best preformance (Rm-max= 668 Mpa, Rp0.2-max= 635 Mpa, A25mm-max= 8.52%) in transverse direction. Nearly all the samples pre-treated by various cryogenic processes obtain stable plastic deformation capacity. Generally, there exist geometric recrystallization, continuous recrystallizaion and discontinuous recrystallization, to some extent in different period of cryogenic-aging process. The final morphology is the result of a mutual compromise between pinning effect originated from cryogenic or natural aging precipitates and recrystallization driving force originating from the energy stored in cryogenic or pre-tensile deformed microstructure. For the thick plate of hot-rolled AA7055, the pair of original rolling Brass components can be enhanced by cryogenic treatment or compressive deformation along transverse direction. But the final texture and the morphology of Σ3nGBs are affected mainly in artificial stage due to various abilities of recovery and discontinuous recrystallization in different directions. Tensile plastic deformation and cycled cryogenic treatment can destroy the Brass components, together with continuous straight geometrically necessary boundaries, more effectively. Since precipitation is probablely accelerated through pre-treatments, a modification of artificial aging time has promising prospect to achieve more excellent mechanical performance.