7075铝合金双辊铸轧工艺与组织性能研究

发布时间：2018-06-07 12:09

本文选题：双辊铸轧 + 7075铝合金　；参考：《辽宁科技大学》2016年硕士论文

【摘要】：7075铝合金是Al-Zn-Mg-Cu系最重要的合金之一,属于热处理可强化合金,因其具有高强高韧性,主要应用于航空航天领域的高应力结构件。双辊铸轧是铝合金加工方式中的一种前沿技术,它将传统铸造和轧制过程合二为一,具有流程短、成本低等优点。目前,针对于7075铝合金的生产加工方法主要有铸造、轧制、挤压等,而7075铝合金的双辊铸轧工艺尚处于实验研究阶段。本文采用双辊铸轧的方法制备了7075铝合金薄板,通过多组实验探究双辊铸轧最佳工艺条件,研究了不同工艺参数对铸轧板组织性能的影响。通过OM、SEM、EDS等方法对7075铝合金铸锭、铸轧板以及热处理后铸轧板进行测试分析,利用UTM5305电子万能实验机和维氏硬度计对铸轧板的力学性能和硬度进行了测试。通过多组实验发现,当浇注温度为993K时,铸轧速度越快,铸轧板的成型性越差,同时所制备铸轧板的晶粒越粗大,力学性能也更差;当浇注温度在963K-973K时,铸轧速度越快,所制备铸轧板的晶粒越细小,力学性能也更好。制备的7075铝合金铸轧板组织是由边部细长的枝晶和芯部等轴晶组成,晶粒尺寸从表层到芯部逐渐增大,表层晶粒铸轧特点最为明显;在晶界及晶内都有第二相的存在,表层第二相析出量要大于芯部的析出量;铸轧后合金硬度最高可达130.9HV,抗拉强度最高可达283.8MPa。经固溶处理的铸轧板组织中第二相明显减少,晶界得到明显细化,力学性能也有明显的提高;经时效处理的样品组织中有明显的脱溶现象,对其硬度进行测试发现,时效处理对样品硬度的强化作用很大,时效处理后硬度可以达到164.7HV。
[Abstract]:7075 aluminum alloy is one of the most important alloys in the Al-Zn-Mg-Cu system. It belongs to the heat-treated alloy, because of its high strength and high toughness, it is mainly used in the field of aerospace high-stress structural parts. Twin roll casting is a kind of advanced technology in aluminum alloy processing. It combines the traditional casting and rolling process and has the advantages of short process and low cost. At present, the main production and processing methods for 7075 aluminum alloy are casting, rolling, extrusion and so on, while the two-roll casting and rolling process of 7075 aluminum alloy is still in the experimental stage. In this paper, 7075 aluminum alloy sheet was prepared by means of double roll casting. The optimum technological conditions of double roll casting were investigated through many experiments, and the effect of different technological parameters on the microstructure and properties of cast rolling plate was studied. The mechanical properties and hardness of 7075 aluminum alloy ingot, casting plate and heat treated plate were tested by means of UTM5305 electronic universal tester and Vickers hardness tester. Through many experiments, it is found that when pouring temperature is 993K, the casting speed is faster, the formability of the cast and rolling plate is worse, and the grain size is bigger and the mechanical properties are worse, and the casting speed is faster when the pouring temperature is at 963K-973K. The smaller the grain size, the better the mechanical properties. The microstructure of the 7075 aluminum alloy cast rolling plate is composed of thin dendrite and equiaxed core, the grain size increases gradually from the surface to the core, the characteristics of the surface grain casting and rolling are most obvious, and the second phase exists in the grain boundary and in the grain. The precipitation amount of the second phase in the surface layer is larger than that in the core, and the highest hardness and tensile strength of the alloy after casting and rolling are 130.9 HVand 283.8 MPA, respectively. The second phase in the structure of cast and rolled plate treated by solution treatment was obviously reduced, the grain boundary was refined obviously, and the mechanical properties were improved obviously. The hardness of the samples was strengthened by aging treatment, and the hardness of the samples reached 164.7 HV after aging treatment.
【学位授予单位】：辽宁科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG146.21;TG335.9

【相似文献】