基于搅拌摩擦加工技术制备高硅铝合金的研究

发布时间：2018-03-18 09:01

本文选题：高硅铝合金　切入点：搅拌摩擦加工　出处：《合肥工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：高铝硅合金具有比重小、导热性好、耐磨耐蚀性好、强度高、硬度大以及易回收等优点,被广泛地应用于汽车、飞机、坦克及船用发动机等工业部门中。但是高硅铝合金常用的制备方法各有优缺点,限制了高硅铝合金材料的制备及应用。因此选择合适的制备工艺,以得到颗粒细小、分布均匀、尖端和棱角较少的高硅铝合金成为了高硅铝合金制备工艺的研究方向。搅拌摩擦加工技术(FSP)利用搅拌头所造成加工区材料的剧烈塑性变形、混合、破碎和热暴露,可以实现微观结构的致密化、均匀化和细化。搅拌摩擦加工技术一方面可以用来制备铝硅合金材料,另一方面也可以用来消除有缺陷铸造铝硅合金中的缺陷。本文在研究高硅铝合金性能及常用制备方法的基础上,利用自主设计的搅拌工具及工装夹具,采用搅拌摩擦加工添加硅颗粒法和铸造加搅拌摩擦加工法制备高硅铝合金材料。结果表明:选择锥台带螺纹型搅拌针,搅拌摩擦加工添加硅颗粒法和铸造加搅拌摩擦加工法均可以制备得到硅颗粒分布均匀、无缺陷的高铝硅合金材料。最佳的工艺参数为搅拌针旋转速度为950 rpm、进给速度为47.5mm/min、交替更改搅拌方向搅拌4道次。但是搅拌摩擦加工添加硅颗粒法制备得到的高硅铝合金中硅含量仅仅能达到14.2%,不能满足试验及使用要求。对采用铸造加搅拌摩擦加工法制备得到的Al-40Si材料进行组织及性能分析。铸造加搅拌摩擦加工后硅颗粒得到了显著地细化,硅颗粒平均直径在3μm左右;硬度值由铸造母材的70 HV提高到了120 HV左右,提升了60%左右;拉伸强度由铸造母材的50 MPa左右提高到了接近于270 MPa,几乎达到了母材拉伸强度的5倍;在摩擦磨损试验中,搅拌后材料的磨损量几乎不随着加载力的增加而增加,高硅铝合金的耐磨性得到了显著地改善。
[Abstract]:High Al-Si alloy has the advantages of small specific gravity, good thermal conductivity, good wear and corrosion resistance, high strength, high hardness and easy to be recovered, so it is widely used in automobile, aircraft, etc. In the industrial sectors such as tank and marine engine, however, the common preparation methods of high silicon aluminum alloy have their own advantages and disadvantages, which limit the preparation and application of high silicon aluminum alloy materials. High silicon aluminum alloy with low edge and low angle has become the research direction of preparation technology of high silicon aluminum alloy. FSPS (friction stir processing technology) makes use of the stirring head to cause severe plastic deformation, mixing, crushing and thermal exposure of the materials in the processing zone. It can realize the densification, homogenization and refinement of microstructure. Friction stir processing technology can be used to prepare Al-Si alloy materials on the one hand, On the other hand, it can also be used to eliminate the defects in Al-Si alloy. On the basis of studying the properties and common preparation methods of high-silicon aluminum alloy, this paper makes use of the self-designed mixing tool and fixture. High silicon aluminum alloy materials were prepared by friction stir processing by adding silicon particle method and by casting and friction stirring process. The results show that the taper table with thread type stirring needle is selected. The distribution of silicon particles can be obtained by adding silicon particles in friction stir processing and casting with friction stir processing. The optimum technological parameters are as follows: the rotating speed of the stirring needle is 950 rpm, the feed speed is 47.5 mm / min, and the stirring direction is changed alternately for 4 passes. However, the friction stirring process with the addition of silicon particle method is high. The content of silicon in silicon aluminum alloy can only reach 14.2, which can not meet the requirements of test and application. The microstructure and properties of Al-40Si prepared by casting and friction stir processing are analyzed. The silicon particles after casting and friction stir processing are analyzed. We get a significant refinement, The average diameter of silicon particles is about 3 渭 m, the hardness is increased from 70 HV to 120HV, and the tensile strength is increased from 50 MPa to nearly 270MPa, which is almost 5 times of the tensile strength of the base metal. In the friction and wear test, the wear resistance of high silicon aluminum alloy was improved significantly with the increase of loading force.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21

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