7050铝合金时效成形工艺及力学性能研究

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南昌航空大学硕士学位论文
目录
目录
摘要..................................................................................................................................I Abstract............................................................................................................................II 第一章 绪论 ............................................................................................................... 1 1.1 研究背景与意义.............................................................................................. 1 1.2 1.3 1.4 1.5 1.6 整体壁板成形方法比较 ................................................................................... 2 国内外时效成形研究....................................................................................... 2 时效成形技术当前研发趋势 ............................................................................ 6 时效成形在航空工业的应用 ............................................................................ 6 课题来源及研究内容....................................................................................... 7
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Creep age forming technology and related mechanical properties of 7050 aluminum alloy sheets
A Dissertation Submitted for the Degree of Master
On Material Processing Engineering
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Abstract
As an important technology for large integral panels, creep age forming (CAF) has the unique advantages in manufacturing aerospace devices and integral panels of giant planes.To improve the forming technology and effectively predict the springback law during CAF, the creep age forming experiments on artificially aged 7050 aluminum alloy have been conducted based on theoretical study. Firstly, by orthogonal experiments, the relationships between the main technological parameters (age temperature, age time and pre-deformation) and springback of 7050 aluminum alloy after CAF were studied, and the involved influences of such parameters were investigated. According to range and variance analysis, experimental results show that the factors influencing springback are ranged in such an order, age temperature (T), age time (t ) and pre-deformation radius ( R). Namely, T has the most important influence on springback ,while t and R followed by. Secondly, the variations of the springback of artifically aged 7050 aluminum alloys in the CAF were characterized by deflection and radius method s. The curve and 3D surface plots between springback rate and technological parameters were developed according to experimental response values. The results indicate that there is a little difference between them, but both of the two methods can describe the springback rate of 7050 aluminum alloys in the CAF. According to the laws of springback rate curves, it is not hard to find that, to a certain range, the higher the temprature, the longer the time, and the larger the pre-deformation radius, the springback is much lower after CAF. The 3D curve surface can predict the springback rate ranges effectively on the different conditions. Finally, the mechanical properties of the samples after CAF were tested. Comparative studies on mechanical properties and microstructure between creep age forming and artificial aging pieces were conducted by scanning electron microscope
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摘要
时效成形技术作为整体壁板的重要成形方法， 在航空航天器件及大飞机整体 壁板制造方面具有独特优势。为完善时效成形工艺研究，有效预测时效成形后试 件的回弹规律，本文在理论分析的基础上，以 7050 铝合金为对象展开时效成形 工艺研究。 首先设计正交实验，研究 7050 铝合金时效成形主要工艺参数与回弹率之间 的关系，探讨试样预弯半径 R、时效温度 T、时效时间 t 三个主要工艺因素对回 弹的影响。并采用极差及方差分析法得出三种实验因素对回弹影响的主次顺序。 实验结果表明，时效因素对回弹的影响顺序为：T>t>R，即时效温度对回弹的影 响最大，时间次之，预弯半径对回弹的影响最小。 其次 ，采用半径法及挠度法两种回弹定义方法，对不同工艺条件下时效成 形后试件的回弹率进行表征， 并根据回弹数值制定回弹率与工艺参数之间的曲线 及 3D 曲面图。结果表明，两种回弹定义方法均可描述 7050 铝合金时效成形后 试件的回弹率，数值差别不大。综合回弹规律曲线可知，在一定范围内，温度的 越高，时间越长，预弯半径越大，时效成形后试样的回弹率越低。回弹规律曲面 图可有效预测时效成形工艺条件下试件的回弹范围。 最后，对时效成形后试样的力学性能进行测试。通过静态拉伸实验，断口 SEM 分析，硬度测试及电导率测试等方法，比较时效成形件与无应力时效试件 的力学性能差异，重点分析外加载荷对 7050 铝合金性能的影响。实验数据表明： 经时效成形处理后的试样，强化效果不太显著。时效成形温度高于 180℃时，试 样的抗拉强度明显降低，7050 铝合金进入过时效状态。综合考虑时效成形后试 样的成形率及力学性能，得出对经固溶自然时效态的 7050 铝合金，其最佳时效 温度为 160℃，且时效时间不应长于 15h。与无应力时效试样相比，经时效成形 处理后，试样的抗拉强度及硬度峰值出现时间滞后，试样强度、硬度、电导率均 高于无应力时效试样。 关键词：7050 铝合金，时效成形，人工时效，回弹，力学性能
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(SEM), hardness testing and electrical conductivity testing. Based on the experimental results, the influences of stress on 7050 aluminum alloy were discussed. The experimental data show that, after age forming processing, strengthening effect of samples are not significant. With an age forming temperature higher than 180 ℃ , 7050 aluminum alloy has entered over-aging condition, the tensile strength decreased obviously . It is necessary to comprehensively consider the springback rate and mechanical properties of the samples, so the best age temperature of 7050 aluminum alloy is about 160℃ and the limitation of time should not be longer than 15 h. Compared with no-stress aging specimen, after age forming, the peak time of tensile strength and hardness lags, and strength, hardness and electric conductivity of the samples were higher than no-stress aging test specimen. Keywords : 7050 aluminum alloy, age forming, artificial aging, springback, mechanio Li
Under the Supervision of
Prof. LI Jun-chu
(School of Aeronautical Manufacturing Engineering) Nanchang Hangkong University, Nanchang, China June, 2014
分类号：TG306
学校代码：10406 学号：110080503028
南昌航空大学 硕 士 学 位 论 文
（学位研究生）
7050 铝合金时效成形工艺及力学性能研究
硕士研究生：肖丽 导 师：黎俊初 教授
申请学位级别：硕 士 学科、专业：材料加工工程 所在单位：南昌航空大学 答辩日期：2014 年 6 月 授予学位单位：南昌航空大学
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