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摘要本课题对试样进行两种处理方式：采用正向挤压和轧制的加工方式制备织构组份和强弱不同的细晶镁合金AZ31样品，接着进行退火处理，使两种状态的试样晶粒尺寸相同；对挤压得到的试样退火不同的时间从而在保证晶粒取向相同的情况下使晶粒尺寸不同。通过这两种方式将晶粒尺寸和织构这两大影响变形镁合金力学性能的因素分离开来。
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利用金相观察、力学性能实验、极图和取向分布函数(ODF)测试等手段分析了AZ31不同状态下组织、性能的演变，重点探讨了织构对镁合金中存在的Hall-Peteh关系的影响以及镁合金中存在的拉伸屈服强度 (TYS)和压缩屈服强度 (CYS)不对称现象。造成这种现象的原因在于孪生对变形过程的影响。同时，取向因子变化大，相应地，外在的屈服强度变化也会比较大，这也从侧面反映出了强度随晶粒取向变化的趋势，并且也是拉压屈服不对称性出现的一个重要原因。9204
研究结果表明，具有不同织构组份和强弱的变形镁合金其拉压屈服强度和晶粒尺寸间均符合Hall-Petch关系，同时获得了拉压屈服强度与AZ31晶粒尺寸d之间的拟合公式，分别为拉伸时σs=43+547.8*d-1/2，压缩时为σs=114.4+963.9*d-1/2。
关键词 变形镁合金 织构 晶粒尺寸 Hail-Petch关系 拉压不对称
毕业设计说明书（论文）外文摘要
Title Effect of texture on mechanical properties of magnesium alloy
Abstract
In this work, samples was treated with two ways: a combined of rolling and forward extrusion method was employed to AZ31 magnesium alloy for preparing samples with fine grains and different textures, then annealing was introduced to the samples to make the grain sizes of the samples of two statuses same; the extrusion samples was annealed with different time to make different grains when the grain orientation was similar. So far, the two factors that were grain size and texture which made the most contribution to its mechanical property in have been separated reasonably by these two ways.
Observation of experiments of mechanical properties, pole figures and Orientation Distribution Function (ODF) of AZ31 in different states were analyzed to reveal the mechanism of how texture performing on the Hall-Petch relation. Tension and compression yield asymmetry in wrought magnesium alloys was also discussed. The reason of this phenomenon is the effect of twinning on deformation behavior. At the same time, the more the orientation factor changes, the more the yield strength changes. It also reflects the tendency of the change of strength with the grain orientation in another aspect while it’s also an important reason of tension-compression yield asymmetry.
The results show that, the yield strength and grain size in both samples which have different textures obey the Hall-Petch relation. That are, σs=43+547.8*d-1/2 in tension and σs=114.4+963.9*d-1/2 in compression.
Keywords wrought magnesium alloy, texture, grain size, Hall-Petch relation, tension-compression yield asymmetry
目 录
1 绪论 1
1.1 镁合金简介 1
1.1.1 镁及镁合金简介 1
1.1.2 镁合金塑性变形的位错理论 1
1.2 织构 2
1.2.1 概念及研究意义 2
1.2.2 形成机理 3
1.2.3 取向分布函数（Orientation distribution function, ODF） 5
1.2.4 镁合金中主要的变形机制 9
1.3 影响塑性变形行为的主要因素 11
1.3.1 织构 11
1.3.2 晶粒尺寸 13
1.4 本文主要研究内容 14