中强高导铝合金线的制备与性能研究

发布时间：2017-12-30 19:00

  本文关键词：中强高导铝合金线的制备与性能研究　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 铝合金导线 合金元素 性能 热处理 加工工艺

【摘要】：Al-Mg-Si合金由于具有良好的力学性能、导电性、塑性成形性及耐腐蚀性而广泛应用于远距离、大跨越输电线路中。为满足输电线路增容改造的需求,开发一种新型中强高导铝合金导体材料,在保证合金强度的同时,进一步提高材料的导电性,并应用于制造中强全铝合金绞线,具有较好的综合优势。本文以架空裸导线用Al-Mg-Si合金导体材料为研究对象,调整Mg、Si、混合稀土RE和B元素进行合金化处理设计出合金成分,对比不同加工工艺下合金的组织及性能,得出优化的Al-Mg-Si-RE-B合金成分,探讨了优化的Al-Mg-Si-RE-B合金的铸态组织、稀土相及非平衡相组成等,研究了均匀化处理、不同加工工艺及时效对合金组织与性能的影响,制备出高性能的中强高导Al-Mg-Si-RE-B合金单丝。主要研究结果如下:(1)通过综合对比四种设计的合金在不同T8态下的抗拉强度、导电率和伸长率,得出最优的合金成分为Al-0.32Mg-0.42Si-0.2RE-0.08B,此时合金单丝的抗拉强度、导电率和伸长率可达到246.67MPa、60.12%IACS和6.9%。最优合金铸态时抗拉强度和导电率为105.0MPa和56.42%IACS。(2)最优合金的铸态组织中稀土元素在长条状α(Al-Fe-Si)附近处富集,形成了不含Fe元素的球状Al-Si-(La/Ce)复杂物相。此外,稀土RE和B产生交互作用,形成了Al-B-(La/Ce)相。非平衡组织中存在大量的Al-Fe-Si三元共晶相,其中长条状或鱼鳞状的α(Al-Fe-Si)相的存在较多。(3)不同均匀化处理下,随着温度(540℃、560℃、580℃)的升高或保温时间(6h/7h/8h/9h)的增加,最优合金的硬度呈下降趋势,导电率呈上升趋势,最后均趋于稳定。对比最优合金的显微组织、导电率和硬度的变化,得到最佳均匀化处理工艺为570℃下保温8h,导电率达到57.12%IACS。(4)Al-0.32Mg-0.42Si-0.2RE-0.08B合金单丝在150℃、170℃和190℃时效时,抗拉强度随时效时间的增加呈先增加、后降低的变化规律。随着时效温度升高,铝合金单丝强度达到峰值的时间越少;时效温度越高,达到的峰值并不一定越高。Al-0.32Mg-0.42Si-0.2RE-0.08B合金单丝在150℃、170℃、190℃和210℃时效时,随着时效时间的增加,导电率呈递增的变化趋势,最后趋于稳定,但是导电率增加速率存在不同。时效时间相同时,温度越高,铝合金单丝的导电率越高。(5)综合考虑导线的设计原则和时效温度、时效时间等对合金单丝性能的影响规律,得出Al-0.32Mg-0.42Si-0.2RE-0.08B中强铝合金单丝的合理时效工艺为190℃下保温9h,其抗拉强度、导电率和伸长率分别为241.82MPa、60.24%IACS和6.2%。
[Abstract]:Al-Mg-Si alloy is widely used in long distance and long span transmission lines because of its good mechanical properties, electrical conductivity, plastic formability and corrosion resistance. A new type of medium and high conductance aluminum alloy conductor material is developed, which not only ensures the strength of the alloy, but also improves the electrical conductivity of the material, and is used in the manufacture of medium and strong all aluminum alloy strands. In this paper, the Al-Mg-Si alloy conductor material for the bare wire is studied, and the Mg-Si alloy is adjusted. The alloy composition was designed by alloying RE and B elements, and the optimized Al-Mg-Si-RE-B alloy composition was obtained by comparing the microstructure and properties of the alloy with different processing processes. The as-cast structure, rare earth phase and non-equilibrium phase composition of the optimized Al-Mg-Si-RE-B alloy were discussed. The effects of homogenization, different processing processes and aging on the microstructure and properties of the alloy were studied. The main results are as follows: (1) the tensile strength of the four designed alloys under different T8 states is compared by synthetically comparing the tensile strength of the four kinds of alloys. The optimum alloy composition is Al-0.32Mg-0.42Si-0.2RE-0.08B. the tensile strength of the single wire is obtained. The conductivity and elongation can reach 246.67 MPA. The tensile strength and electrical conductivity of the best cast alloy are 105.0 MPA and 56.42 IACS, respectively. The rare earth elements in the as-cast microstructure of the optimal alloy are enriched near the long stripe 伪 -Fe-Si. In addition, rare earth RE and B interact with each other. A large number of Al-Fe-Si ternary eutectic phases were formed in the nonequilibrium structure. Among them, the existence of 伪 -nAl-Fe-Si) phase in the shape of long strip or fish scale is much more than that of other phases. Under different homogenization treatment, with the temperature of 540 鈩，

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