CuSn10合金半固态浆料转棒诱导形核法制备及其挤压铸造成形

发布时间：2018-07-28 09:47

【摘要】：铜合金是应用最为广泛的金属材料之一,其最主要的应用领域为电气和电子工业,占铜总消耗量50%以上。作为原材料用于生产和制造电缆、开关、线路板以及电机等产品；在机械、车辆的生产中,主要用于生产工业用阀门和配件、仪表、轴承、耐高温模具、热交换器等。使用传统方法浇铸的铜合金容易产生气孔、缩松、裂纹以及偏析等常见的铸造缺陷,组织均匀性较差,严重影响了铜合金的使用性能和使用寿命。同时,由于铜合金的熔点高,在挤压铸造的过程中存在模具使用寿命短的致命问题。半固态加工技术以其工艺流程较短、充型过程平稳、能耗低、模具使用寿命长等优点被认为是21世纪最有前途的材料加工成形方法,半固态加工制备的零件组织致密,力学性能好而便于机械加工,近终成形使得机械加工时加工量减少,而半固态浆料的制备是该技术的关键所在。采用半固态成形技术加工铜合金,有利于降低浇注时模具的温度从而大幅提高模具的使用寿命,改善铜合金组织的均匀性从而提高其使用寿命、扩大其应用范围。本文采用转棒诱导形核法制备CuSn10合金半固态浆料,并对半固态浆料进行挤压铸造成形获得零件,主要研究内容如下：采用转棒诱导形核法制备CuSn10合金半固态浆料,分析转棒直径、转棒转速对半固态浆料显微组织的影响。实验结果表明,转棒诱导形核法对CuSn10合金熔体的凝固有明显的促进形核作用,α-Cu相得到细化,枝晶状组织被消除,明显改善了组织不均匀的问题。但是在不同实验参数下获得的半固态坯料组织有所不同：外径为e45mm和(?)75mm的不锈钢转棒在相同转速下制备的浆料相比,(?)75mm获得的坯料微观组织中晶粒细化和球化效果更好,组织分布更加均匀；通过对(?)75mm的不锈钢转棒在不同转速条件下制备的浆料比较发现,随着转棒转速的提高,转棒的诱导促进形核作用呈现出先增强后减弱的趋势,而并非简单的逐步增强的趋势。当浇注温度为1080℃(低过热度状态),转棒转速为500r/min时,获得的浆料组织中晶粒细化效果最好,晶粒平均直径达到42.3 gm,形状因子为1.58,同时组织中液相率最高为23.2%。针对所制备的合金半固态浆料进行挤压铸造成形,分析压力、压头压速对零件显微组织和抗拉强度的影响。实验结果表明：压头压速一定时,随着压力的增加,零件的抗拉强度随之提高,从95.3MPa提高到232.4MPa；压力一定时,随着压头压速的提高,零件的抗拉强度也随之提高,从199.2MPa提高到232.4MPa1。与液态挤压铸造成形相比,半固态挤压铸造制备的零件抗拉强度从183.1MPa提高到232.4MPa,提高了26%；延伸率从原来的2.97%提高到12.1%,提高了4.1倍。通过对拉伸试样断口进行扫描分析发现,随着压力和压头压速的提高,获得的零件组织更加致密,零件的的拉伸断裂方式为准解离断裂。
[Abstract]:Copper alloy is one of the most widely used metal materials. Its main application fields are electrical and electronic industries, accounting for more than 50% of the total copper consumption. Used as raw materials for producing and manufacturing cables, switches, circuit boards and motors, etc. In the production of machinery and vehicles, it is mainly used in the production of industrial valves and accessories, instruments, bearings, high temperature resistant dies, heat exchangers, etc. The common casting defects, such as porosity, shrinkage, crack and segregation, are easily produced in the copper alloy cast by the traditional method, and the structure uniformity is poor, which seriously affects the service performance and service life of the copper alloy. At the same time, due to the high melting point of copper alloy, die life is short in squeeze casting. Semi-solid processing technology is considered to be the most promising material forming method in the 21st century because of its advantages such as short technological process, stable filling process, low energy consumption and long service life of die. The mechanical properties are good and easy to be machined. Near-end forming reduces the machining quantity, and the preparation of semi-solid slurry is the key of this technology. Using semi-solid forming technology to process copper alloy is beneficial to reduce the mold temperature and increase the service life of die, improve the structure uniformity of copper alloy and extend its application range. In this paper, CuSn10 alloy semi-solid slurry was prepared by rod-induced nucleation method, and the semi-solid slurry was formed by squeeze casting. The main research contents are as follows: the semi-solid slurry of CuSn10 alloy was prepared by rotor-induced nucleation method. The effect of rotating rod diameter and rotating speed on microstructure of semi-solid slurry was analyzed. The experimental results show that the rod-induced nucleation method can obviously promote the nucleation of CuSn10 alloy melt, the 伪 -Cu phase is refined, the dendritic structure is eliminated, and the problem of microstructure inhomogeneity is obviously improved. However, the microstructure of semisolid billets obtained under different experimental parameters is different. Compared with the slurry prepared with stainless steel rotating rods with outer diameter of e45mm and (?) 75mm at the same speed, the microstructure of the billets obtained by (?) 75mm is better in grain refinement and spheroidization. The results showed that with the increase of rotating speed, the nucleation of stainless steel rotating rod of 75mm increased first and then weakened, the microstructure distribution was more uniform, and the results showed that with the increase of rotating speed, the nucleation effect of stainless steel rotor rod increased first and then weakened, and the results showed that with the increase of rotating speed, the nucleation of stainless steel rotor rod increased firstly and then weakened. Rather than a simple incremental trend. When the pouring temperature is 1080 鈩，

本文编号：2149697