7050铝合金尺寸热稳定性研究
发布时间:2018-04-20 05:09
本文选题:7050铝合金 + 线膨胀系数 ; 参考:《青岛理工大学》2015年硕士论文
【摘要】:随着铝合金材料的研发与使用,铝合金的优异性能逐渐显现了出来,使得各种铝合金被越来越广泛地使用于众多领域。近几年随着高铁行业的快速发展,节能降耗意识在全球制造业的提高,对高速动车性能要求的不断提高,大量采用高强度铝合金结构件成为一种趋势,铝合金结构件可以大大减轻高速动车的重量,减少燃料的使用提高动车的机动性,同时,使得携带负载的能力大大提高,有效的缓解了安全、环保、能源[29]这三大课题,高速动车中零部件材质逐渐采用高强度铝合金替换原来的各种钢材。然而由于铝合金材料具有较大的热膨胀系数,导致其在加工与使用过程中的尺寸稳定性受温度变化的影响较大,进而导致了铝合金零部件经济性的降低。本研究主要从理论分析与实验分析两个角度出发对铝合金的尺寸热稳定性进行较为深入的研究,希望研究结论可为正确制定铝合金的加工工艺,特别是铝合金零部件热变形的补偿,提供基础的理论性指导,同时可为建立精密工程中常用材料的精确热膨胀系数参考标准提供一定的参考依据[30]。通过对材料热膨胀物理性以及材料热膨胀现象与其比热容(特别是晶格振动比热容)的关系等的研究分析,发现了7050-T74铝合金的线膨胀系数与温度变化之间的相关性[31]。通过铝合金轴箱体热变形实验,初步得到了7050-T74铝合金在18℃-34℃温度范围内孔径尺寸变化量与温度之间的关系及其在该温度范围内的平均线膨胀系数[32]。通过利用DSC实验仪器及相关软件进行铝合金比热容随温度变化测量实验,探究了7050铝合金尺寸热稳定性与其比热容变化的相关性,并根据实验得出的7050-T74铝合金热容随温度变化的变化规律,通过格留乃申公式得出了线膨胀系数随温度变化的近似数学表达式以及7050-T74铝合金在20℃~100℃(293K~373K)温度范围内材料线膨胀系数的平均值。通过铝合金金相组织随温度变化观察实验,探究了温度变化时7050-T74铝合金组织变化对铝合金尺寸热稳定性的影响。通过ABAQUS对750铝合金轴箱体建立有限元模型,并划定网格类型;对有限元模型施加相应的边界条件和约束,包括参数化载荷;分析软件将根据零件几何模型对相应的有限元模型进行解算,并对解算结果作相应的后处理[33]。
[Abstract]:With the development and application of aluminum alloy materials, the excellent properties of aluminum alloy gradually appear, making various aluminum alloys are more and more widely used in many fields. In recent years, with the rapid development of high-speed rail industry, the awareness of energy saving and consumption reduction has been improved in the global manufacturing industry, and the performance requirements of high-speed motor cars have been continuously improved. It has become a trend to adopt a large number of aluminum alloy structures with high strength. Aluminum alloy structure can greatly reduce the weight of high-speed motor cars, reduce the use of fuel to improve the mobility of motor vehicles, at the same time, make the carrying capacity of load greatly improved, effectively alleviate the safety, environmental protection, energy [29] three major topics, High-strength aluminum alloy is gradually used to replace all kinds of steel in high-speed motor car. However, due to the large thermal expansion coefficient of aluminum alloy materials, the dimensional stability of aluminum alloy materials in the process of processing and use is greatly affected by the temperature change, which leads to the reduction of the economy of aluminum alloy parts. In this study, the dimension thermal stability of aluminum alloy was studied from two aspects of theoretical analysis and experimental analysis, and the conclusion of the study could be used to correctly formulate the processing technology of aluminum alloy. In particular, the compensation of thermal deformation of aluminum alloy parts provides basic theoretical guidance, and can also provide a certain reference basis for the establishment of reference standard for accurate thermal expansion coefficient of materials commonly used in precision engineering [30]. By analyzing the physical properties of material thermal expansion and the relationship between material thermal expansion phenomenon and its specific heat capacity (especially lattice vibration specific heat capacity), the correlation between linear expansion coefficient and temperature change of 7050-T74 aluminum alloy has been found [31]. The relationship between the change of pore size and temperature and the average linear expansion coefficient of 7050-T74 aluminum alloy in the temperature range of 18 鈩,
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