挤压铸造镁合金的组织和性能的观察与分析（本科毕业论文设计）.doc

摘 要

镁合金，作为21世纪的绿色金属结构材料，具有比重轻、比强度高、阻尼性、减震性及切屑加工性、导热导电性好、电磁屏蔽能力强、可回收等一系列优点，加之人们对环保意识的增强和对汽车轻型化的需求，镁正受到人们越来越多的关注。用于制造轮毂常用的镁合金材料为AM60，但该合金的强度低，不能够满足轮毂在不同工作环境中的使用要求。
本文以AM60B为基体，通过改变Al, Zn含量和加入一定量的稀土元素Ce，用挤压铸造的方法，制造成为AZ71E镁合金，然后对这两种材料对比进行铸态组织金相分析和力学性能测试。实验结果发现，AZ71E的微观组织和综合性能比AM60B得到较大改善，微观组织均匀，晶粒细小，材料的抗拉强度 b为261.71MPa，屈服强度 0.2为157.29MPa，硬度70.05HRE,分别提高了4.8%,13.3%和15.3%，而延伸率为10.06%，下降了12.8%，进而更适合于制造轮毂。


关键词：镁合金、AM60B、AZ71E、挤压铸造、金相组织、力学性能

Abstract
As a “green” structural material for 21st century, the magnesium alloys have a series of excellent characteristics, such as low specific density, high specific strength and rigidity, better damping capacity, good casting properties, excellent thermal conductivity and electromagnetic shielding, and easy to recycle, etc. In addition, with higher awareness of environmental protection and increased needs for lower weight of automobile, researchers are now paying much attention to the magnesium alloys. AM60, a magnesium alloy, is often used to make wheel hubs. However, this alloy can not be commonly used in different circumstances because of lower strength.
This paper is focused on study of a new Mg alloy called AZ71E made from AM60B by changing the Al, Zn composition of AM60B and addition of rare earth Ce. The new alloy AZ71E was squeeze cast together with AM60B, followed by microstructure analysis and mechanical properties test. It is concluded that the microstructure and properties of AZ71E are improved a lot. For ZA71E, uniform microstructure and small grains have been obtained, the tensile strength is 261.71MPa, the yield strength is 96.32MPa and the hardness is 70.05HRE, which increase 4.8%, 13.3% and 15.3% respectively in comparison with AM60. The elongation of AZ71E is 10.06%, decreased 12.8% compared with AM60. Thus, the new alloy AZ71E is more suitable for wheel hubs.


Key words: Magnesium Alloy, AM60B, AZ71E, squeeze casting, metallurgical structure, mechanical property.










目 录
中文摘要 1
ABSTRACT 2
1 绪 论 5
1.1 引言 5
1.2 镁合金材料的研究现状 6
1.2.1 镁及镁合金 5
1.2.2 镁的提取和制备 7
1.2.3 镁合金的熔炼和保护 8
1.3 镁的成型技术及发展现状 10
1.3.1 压铸 10
1.3.2 半固态铸造 11
1.3.3 挤压铸造 11
1.3.4 镁合金超塑性 11
1.3.5 冲锻成型 11
2 试验材料及研究方法 16
2.1 试验材料的选择 16
2.1.1 镁中添加合金元素的作用 16
2.2 镁合金的挤压成型 18
2.2.1 挤压成型简介 18
2.2.2 挤压铸造参数的认识 20
3 试验准备及试验过程 21
3.1试验用镁合金材料 21
3.2试验用镁合金材料的制备 21
3.2.1 镁合金的熔炼工艺 21
3.2.2 镁合金浇注工艺 22
3.3 挤压铸造镁合金参数的选择 22
3.4 力学性能测试 23
3.4.1 拉伸性能测试 23
3.4.2 硬度测试 23
3.5 微观组织分析 24
4 实验结果及分析 25
4.1挤压铸造AM60B和AZ71E的显微组织 25
4.2挤压铸造AM60B和AZ71E的力学性能 26
5 结 论 26
参考文献 30