复合镦挤对6061铝合金组织和性能的影响研究

发布时间：2018-06-14 11:43

本文选题：6061铝合金 + 等通道转角挤压　；参考：《昆明理工大学》2017年硕士论文

【摘要】：6061铝合金属于Al-Mg-Si系合金,具有成型性好,耐腐蚀强,密度小等优势,在汽车及航空航天领域运用广泛,是未来可持续发展最具前景的材料之一。随着人们对高强度的轻量金属材料的需求增大,近年来大塑性变形技术发展较快,尤其是等通道转角挤压法(ECAP,Equal channel angular pressing)和多向压缩法(CCDC,Cyclic channel die compression),大塑性变形通过细化晶粒的方法有效地提高材料的强度,而且具有制备工艺简单,成本低廉等优势,越来越多的学者对其进行深入的探索和研究。本论文在等通道转角挤压和多向压缩的基础上,将两种方法结合起来,进行不同路径的复合镦挤,并通过力学性能、X射线衍射、和EBSD方法分析及断口观察,研究复合镦挤工艺对6061铝合金组织和性能的影响。研究结果表明:(1)在35mm/min的挤压速度下,6061铝合金的抗拉强度、显微硬度达到最大,并且随着挤压道次的增加,材料的抗拉强度得到明显提高。(2)试样的道次应变量为60%时,经3道次多向压缩试样的抗拉强度达到293.410 MPa,综合力学性能最好。(3)6061铝合金最佳复合镦挤工艺是镦挤镦,抗拉强度比单独的多向压缩、单独等通道挤压抗拉强度提高了 1.4倍,延伸率也有所提高,晶粒大小从110-130μm细化到了 0.98μm,细晶强化效果最明显,从宏观上表现为抗拉强度和伸长率的增加。
[Abstract]:6061 aluminum alloy is a kind of Al-Mg-Si alloy, which has the advantages of good formability, strong corrosion resistance and low density. It is widely used in the field of automobile and aerospace, and is one of the most promising materials for sustainable development in the future. With the increasing demand for light metal materials with high strength, the technology of large plastic deformation has developed rapidly in recent years. In particular, the equal channel angular extrusion (ECAP) equal channel angular pressing) and the multidirectional compression method (CCDCC) cyclic channel die compression can effectively improve the strength of the material by grain refinement, and have the advantages of simple preparation process and low cost. More and more scholars have deeply explored and studied it. In this paper, on the basis of equal channel angular extrusion and multidirectional compression, the two methods are combined to carry out compound upsetting extrusion with different paths, and the mechanical properties are analyzed by X-ray diffraction, EBSD method and fracture observation. The effect of composite upsetting extrusion process on the microstructure and properties of 6061 aluminum alloy was studied. The results show that the tensile strength and microhardness of the alloy reach the maximum at the extrusion rate of 35mm/min, and the tensile strength of the material increases obviously with the increase of extrusion pass. The tensile strength of the multidirectional compression specimen after 3 passes is 293.410 MPA. The best comprehensive mechanical properties. The best composite upsetting process is upsetting, the tensile strength is more than that of the single multi-direction compression, and the tensile strength of the single equal channel extruding is 1.4 times higher than that of the single equal channel compression. The elongation also increased, the grain size was refined from 110-130 渭 m to 0.98 渭 m, the strengthening effect of fine grain was the most obvious, and the tensile strength and elongation increased macroscopically.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21;TG306

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