双级时效及Cu含量对导电轨用Al-Mg-Si合金性能的影响

发布时间：2018-02-25 17:50

  本文关键词： 导电铝合金 时效制度 电导率 析出相 Cu含量　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：Al-Mg-Si(Cu)合金具有良好的性能如密度低、强度高、良好的延展性等机械性能以及较高的电导率,因此在强度和导电率都有要求的领域,例如轨道交通用的导电轨等获得了广泛的应用。Al-Mg-Si(Cu)合金是可热处理强化的合金,合金的强度主要取决于过饱和A1基体时析出共格或半共格纳米析出相,而合金的导电性则是受固溶元素的数量控制的。在典型的6系列铝合金时效过程中,强度是先升后降,而导电率则是持续上升的。这就造成了强度和导电性能之间的矛盾,目前供货状态的导电轨是处于过时效状态来满足导电率的要求。合金成分和时效制度决定着Al-Mg-Si(Cu)合金中析出物的种类数量,不但影响着强度,还影响着导电率。针对时效制度和成分对导电铝合金性能的影响,。本课题的研究内容主要分为两个部分:第一部分主要研究双级时效对合金综合性能的影响,第二部分主要分析比较不同Cu含量的合金在相同时效制度下综合性能的区别。时效制度的研究结果表明:与单级时效相比,双级时效能够提高6063合金峰值时效的硬度和过时效的硬度,合金的峰值平台时间延长。在一级时效温度90℃+二级时效温度180℃的时效制度下,其抗拉强度、延伸率和电导率分别达到225MPa、12%和56.83%IACS能够满足使用要求。一级时效温度主要影响合金时效初期的析出进程,能够促进GP区的形成,并影响GP区的数分布。二级时效温度控制合金随后的析出进程,能够决定合金在时效不同时间时析出相的类型如针状β"相、杆状β'相,这些析出相将最终决定合金的综合性能。铜元素含量的研究结果表明,与导电轨用6063合金相比,Cu元素的加入能够提高合金峰时效峰值硬度,但会降低合金的电导率。Al-0.8Mg-0.58Si-0.6Cu(wt.%)合金的综合性能良好,其二级时效840min时的抗拉强度、延伸率和电导率分别为225MPa、11.5%和56.90%IACS,在满足使用要求的同时进一步拓宽了工艺区间。Cu元素的加入能够促进针状β"相的析出,改变合金过时效阶段不同析出相的比例。Al-Mg-Si(Cu)过时效阶段强度提高主要归因于过时效阶段残留的针状β"相和板条状Q'相。
[Abstract]:Al-Mg-Si-Cu) alloys have good mechanical properties such as low density, high strength, good ductility and high electrical conductivity. For example, the conductive rail used in rail transit has been widely used. Al-Mg-Si-Cu) alloy is a heat-treatable alloy. The strength of the alloy mainly depends on the precipitation of coherent or semi-coherent nanocrystalline precipitates at supersaturated A1 matrix. The electrical conductivity of the alloy is controlled by the number of solid solution elements. In a typical 6 series of aluminum alloys, the strength rises first and then decreases, while the conductivity increases continuously. This creates a contradiction between strength and electrical conductivity. The current supply state of the conductive rail is in an overaged state to meet the requirements of conductivity. The alloy composition and aging system determine the number of precipitates in the Al-Mg-Si-Cu) alloy, which not only affect the strength, but also the strength of the alloy. The main contents of this paper are divided into two parts: the first part mainly studies the effect of two-stage aging on the comprehensive properties of the alloy. The second part mainly analyzes and compares the comprehensive properties of alloys with different Cu content under the same aging regime. The double stage aging can increase the hardness of 6063 alloy and the hardness of overaging, and the peak plateau time of the alloy is prolonged. The tensile strength of 6063 alloy is increased at the aging temperature of 90 鈩，

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