镁合金拱顶高度胀形系数成形性能毕业论文.doc
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1、目录摘要IAbstractIII第一章 绪论11.1 镁及镁合金材料的性质及工艺特点11.2 合金元素对AZ31B镁合金的影响21.2.1 Al元素的影响21.2.2 Zn元素的影响31.2.3 其它合金元素的影响31.3 镁合金的发展和应用31.3.1 镁合金在汽车工业上的应用41.3.2 镁合金在现代兵器零部件上的应用41.3.3 镁合金在航空航天工业中的发展51.3.4 镁合金在其它领域的应用发展51.4 镁合金现代生产技术51.5镁合金的塑性变形机理71.5.1 滑移变形71.5.2 孪生变形81.6 常见的镁合金塑性加工工艺81.7 金相显微镜101.8 镁合金AZ31B板料成形性能
2、研究进展131.9课题的提出14第二章 有限元模拟基础知识162.1 引言162.2 有限元模拟屈服准则的选择162.3工件与模具接触与摩擦182.3.1 接触方式182.3.2 摩擦的定义192.4单元的类型与求解算法192.5 Deform有限元分析软件20第三章 实验装置233.1 金属板材的冲压成形性能233.1.1 利克辛实验(杯突实验)233.1.2改进的极限拱顶高度实验243.2 极限拱顶高度实验装置25第四章 镁合金成形性能研究314.1板料厚度对镁合金AZ31B成形性能的影响314.1.1极限拱顶高度实验结果314.1.2 DEFORM-2D模拟中摩擦系数的确定334.1.3
3、数值模拟分析344.2 成形温度对镁合金AZ31B板料成形性能的影响374.2.1极限拱顶高度实验结果374.2.1 数值模拟分析394.3 成形速度对极限拱顶高度的影响424.3.1 极限拱顶高度实验424.3.2 数值模拟分析434.4润滑条件对镁合金成形性能的影响454.4.1 不同的板料厚度464.3.2 不同的成形温度474.4.3 不同的成形速度494.5 本章小结50第五章 二次成形对镁合金板料成形性能的影响535.1 预成形高度对二次成形结果的影响535.2 保温时间对二次成形结果的影响565.3 镁合金板料的金相组织575.3.1 金相样品的制备575.3.2 镁合金金相分析
4、585.4 本章小结62第六章 结论与展望666.1 结论666.2 展望68参考文献71致谢78ContentsAbstract(Chinese)Abstract(English)Chapter Instruction1.1 Property and process characteristics of magnesium and magnesium alloy11.2 Impact of alloy elements on AZ31B magnesium alloy21.2.1 Al21.2.2 Zn31.2.3 Other elements31.3 The development and
5、 application of magnesium alloy31.3.1 The application on automobile41.3.2 The application on parts of modern weapons41.3.3 The development on aerospace industry51.3.4 Other filds51.4 Modern production of magnesium alloy51.5 The plastic deformation machnism of magnesium alloy71.5.1 Sliding deformatio
6、n71.5.2 twinning81.6 Common plastic processing of magnesium alloy81.7 Metallographic microscope111.7 The research progress of magnesium alloy AZ31B sheetsformability131.8 Topic proposing14Chapter Sheet metal plastic forming finite element simulation162.1 Instruction162.2 The choice of yield creterio
7、n16 2.3 The contact and friction of workpiece and mold182.3.1 Contact pattern182.3.2 Definition of friction192.4 Unit type and Solving algorithm192.5 Deform finite element analysis software20Chapter Experimental device233.1 Stamping formability of sheet metal233.1.1 Erichsen Test / Cupping Test243.1
8、.2 Modified Limit Dome Height Test253.2 Limited dome height test device25Chapter Formability of magnesium alloy314.1 The sheet thickness314.1.1 LHD test result314.1.2 Determination of the friction coefficient in DEFORM-2D314.1.3 Simulation result314.2 The forming temperature394.2.1 LHD test result39
9、4.2.2 Simulation result394.3 The forming velocity464.3.1 LHD test result464.3.2 Simulation result464.4 Lubrication condition514.4.1 thickness514.4.2 Temperature514.4.3 Velocity514.5 Conclusion59Chapter Double forming process615.1 Preforming height 615.2 Soaking645.3 Microstructure of magnesium alloy
10、 sheet665.3.1 Preparation of metallographic samples665.3.2 Metallographic analysis of magnesium alloy685.4 Conclusion72Chapter Conclusion and Outlooks746.1 Conclusion746.2 Outlooks76References77Acknowlegments82摘要镁合金被誉为21世纪绿色工程材料之一。镁合金的密度较小,镁合金制品整体结构质量轻、能源消耗少。同时镁合金具有较高的比强度和比刚度以及良好的切削加工性能和铸造性能。在高温下,镁合
11、金的塑性较好,能够采用各种塑性成形的方法加工成板材、棒材、型材和粉材,并获得压铸件、锻件和模锻件等。 镁合金板料的塑性成形性能与成形温度、成形速度、板料厚度、工件与模具之间的摩擦等成形参数密切相关。本文采用极限拱顶高度实验装置,着重分析了各成形参数对镁合金AZ31B板料胀形成形性能的影响,并找出提高镁合金板料成形性能的方法。(1)在本文提出的温度范围内(100250),随着成形温度的提高,镁合金板料的成形性能逐渐增强。(2)当板料厚度t为0.6mm时,板料的成形性能是最好的。板料厚度t小于0.6mm时,镁合金AZ31B板料的成形性能随着板料厚度的增加而变好;反之t大于0.6mm时,镁合金AZ3
12、1B板料的成形性能随着板料厚度的增加而变差。(3)对比两种成形速度下(1mm/min和10 mm/min)镁合金板料的极限拱顶高度和胀形系数:较低的成形速度下,镁合金板料的极限拱顶高度和胀形系数较大。降低镁合金板料的成形速度能提高镁合金板料的成形性能,但是过低的成形速度不适合在工业生产中广泛应用。(4)在各种条件下采用二硫化钼润滑时镁合金板料的成形性能均比无润滑时要好。因此本文提出250、t=0.6mm、v=10mm/min、采用时板料的成形性能最好,其极限拱顶高度达38.6mm,胀形系数为0.919。另外,本论文提出镁合金板料的二次成形方法,即先预成形至一定拱顶高度,在成形温度下保温一段时间
13、后再成形至失稳。对比了二次成形与一次成形时镁合金板料的成形性能,并分析了预成形高度与保温时间对二次成形性能的影响;从拱顶高度和胀形系数等宏观角度分析镁合金板料的成形性能;对比了各成形条件下镁合金板料垂直于胀形方向的显微晶粒组织,从内部晶粒变化机理分析二次成形对镁合金板料成形性能的影响,最终找出提高镁合金板料成形性能的方法。关键词:镁合金;AZ31B;拱顶高度;胀形系数;成形性能AbstractMagnesium alloy is known as one of the green engineering materials in 21st century. It has lower densi
14、ty, therefore its products are light, and have lower energy consumption. Besides, magnesium alloy has special strength and stiffness, along with good machining property and casting performance. The formability of magnesium alloys is very good at a high forming temperature. With many kinds of plastic
15、 forming, it can be processed into sheets, rods, profiles and powder materials, as well as castings, forgings and die forgings.The plastic formability of magnesium alloy sheets is concerned with forming temperature, velocity, the thickness of the sheet, and the friction between the mold and the shee
16、ts. In this paper, the Limited Dome height Test is used to explore the impact of forming parameters on the formability of magnesium alloy sheet, resulting in finding the optimum method to raise the forming ability. (1) In the forming temperature range from 100 to 250, the formability is gradually in
17、creasing with the rising of temperature. (2) When the thickness of the sheet is 0.6mm, the formability is optimal. As the thickness of the sheet is lower than 0.6mm, the formability is improved with the increasing of thickness; reversely, the formability is lessened with the increasing of thickness.
18、 (3) Comparing the two forming velocities of 10mm/min and 1mm/min, a lower velocity can improve both limited dome height and bulging coefficient, but it is not suitable for wide application in industrial production. (4) The formability is always better when the sheet is lubricated by some lubricants
19、 such as than that without lubrication. In summary, the optimal forming condition is: a forming temperature of 250, a sheet thickness of 0.6mm, a forming velocity of 10mm/min, and lubrication by , at which the limited dome height can reach 38.6mm and the bulging coefficient is 0.919.On the other han
20、d, a twice-forming method is presented in this paper. This new method is compared with the single forming method, and the impact of preforming height and soaking on twice-formability is analyzed. The limited dome height and bulging coefficient are chose to analyze the formability. The microscopic gr
21、ain structure of the direction that is perpendicular to bulging direction under all kinds of condition is observed, and the impact of twice forming method on the formability of magnesium alloy sheet is analyzed from the view of internal mechanism, finally a method to improve the formability is prese
22、nted.Keywords: magnesium alloy; AZ31B; dome height; bulging coefficient; forming property第一章 绪论1.1 镁及镁合金材料的性质及工艺特点镁元素在自然界中分布广泛,居第八位,是地壳中分布最广的元素之一,约占地壳质量的2.35%1。在镁基中添加其他元素所组成的镁合金,是目前使用最轻的金属结构材料2,提高镁合金的应用范围受到人们的广泛重视。在金属结构材料中,镁合金具有绝对优势3-6:(1)纯镁的密度为1.738g/cm3,镁合金的密度比纯镁稍大,在1.751.85 g/cm3之间,大约是铁的密度的1/4,铝的
23、密度的2/3,与塑料接近。因此采用镁合金材料的产品可以减轻结构重量,降低能源消耗,减少污染排放,同时使运输机械的载重量和速度有较大幅度的提高7。(2)有很高的比强度和比刚度,其比弹性模量与合金钢、高强度铝合金相当,因此采用镁合金制作刚性良好的整体构建,对于构件的整体性能十分有利8。(3)镁合金的阻尼性能好,震动吸收性能好,适合用镁合金制作抗震减震的零部件。(4)镁合金的弹性模量较低,受力时,应力分布均匀,能够防止过高的应力集中。当承受的冲击载荷在弹性范围内,其吸收的能量比铝高50%,所以,适合用镁合金制造承受剧烈冲击的零部件。(5)镁合金的电磁屏蔽性比铝合金好,适宜制作电子产品,如计算机和手机
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