基于ECAP工艺的AZ31镁合金晶粒细化及微观组织演化研究
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密 惠 保
摘 要.......................................................................................Ⅲ
ABSTRACT.........................................................................................Ⅳ
1前言...........................................................................................1
1.1选题依据和意义................................................................................1
1.2镁及镁合金的结构与性能特性........................................................................1
1.3变形镁合金的研究进展...............................................................................3
2镁合金的塑性变形机理分析.......................................................................6
2.1镁合金的晶体结构与位错特征.........................................................................6
2.2镁合金中的滑移....................................................................................7
2.2.1镁合金中的独立滑移系..............................................................................7 [资料来源：http://think58.com]
2.3影响镁合金滑移的主要因素............................................................................9
2.3.1变形温度的影响....................................................................................9
2.3.2变形速度的影响.................................................................................10
2.3.3晶粒度的影响...................................................................................10
2.3.4初始织构的影响...............................................................................10
2.4镁合金中的孪生...................................................................................11
2.4.1镁合金中的孪生模式和孪生要素..............................................................................11
2.4.2镁合金孪生的位错机制..................................................................................12
2.5镁合金的晶间塑性变形机制及GBS...........................................................................13
2.6ECAP工艺...........................................................................................14 [资料来源：http://think58.com]
2.6.1ECAP工艺的原理....................................................................................15
2.6.2ECAP工艺的优势..........................................................................................15
2.6.3ECAP过程中材料的微观结构和变形机理...............................................................16
2.6.4镁合金ECAP工艺的影响参数.................................................................................16
2.6.5ECAP工艺存在的问题及发展方向...........................................................................19
3ECAP工艺的数值模拟..........................................................................................20
3.1ECAP工艺的DEFORM模拟.......................................................................................20
3. 1.1DEFORM软件简介........................................................................................20
3.1.2DEFORM的特点............................................................................................20
3.1.3DEFORM的应用.........................................................................................21
3.2DEFORM模拟实验.............................................................................................21
3.2.1A路径模拟..........................................................................................21
3.2.2BA路径模拟......................................................................................22
3.2.3BC路径模拟.........................................................................................24
3.2.4C路径模拟..........................................................................................25
4实验结果及分析.........................................................................................29
4.1 本课题的实验方案.............................................................................29
4.2等径角挤压实验...................................................................................29
4.2.1实验材料.........................................................................................29
4.2.2退火处理........................................................................................29 [资料来源：http://THINK58.com]
4.2.3等径角变形........................................................................................29
4.3实验结果与分析......................................................................................29
4.3.1AZ31镁合金原样和退火处理后微观组织................................................................29
4.3.2挤压道次对AZ31镁合金晶粒细化及微观组织的影响..........................................30
4.3.3挤压路线对AZ31镁合金晶粒细化及微观组织的影响............................................32
5结论及展望.................................................................................................34
谢 辞.................................................................................................35
参考文献............................................................................................36
摘 要 [来源：http://think58.com]
等通道转角挤压技术是目前制备超细晶粒金属块材的主要研究领域之一。为了研究等通道转角挤压时不同工艺路径对镁合金微观结构及性能的影响。本文首先利用DEFORM软件进行模拟，结果表明，BC应变积累比较均匀，是最佳的挤压路径；采用模具角为90°的模具,以A、BA、BC、C 四种工艺路径对AZ31镁合金进行了等通道转角挤压，分析测试了室温下挤压试样的微观结构及性能。结果表明,随着挤压道次的增加晶粒不断细化，但各挤压路径对AZ31 镁合金的微观组织和性能的影响不同，相比于A、BA、C路径挤压，BC路径挤压获得的晶粒尺寸最小。
关键词：AZ31镁合金；等径角挤压(CEAP)；挤压路线；挤压次数；微观组织
Microstructure evolution in magnesium alloy AZ31 during equal channel angular pressing
Abstract
Equal channel angular pressing technology is the main technical method of producing superfine grain metal materials.In order to investigate the effect of different processing routes for the equal channel angular pressing ( ECAP) on the microstructure and property of magnesium alloy , firstly,using the DEFORM software deform to simulate the AZ31 Mg alloy,the conclusion shows that the BC is the best ECAP route secondly, AZ31 Mg alloy was prepared by means of ECAP in the die , with an intersecting angle (φ) of 90 °and four processing routes of A , BA , BC ,C , respectively. The microstructure and property of the pressed material at room temperature were then measured and analyzed. The results indicate that ,Grain refinement should occur with increasing number of ECAP pass，but different routes have various effects on the microstructure and property of AZ31 Mg alloy. Compared with those pressed via A , BA , C routes , the workpiece pressed via BC route can be obtain the finest gains. [资料来源：http://www.THINK58.com]
Key words: AZ31 Mg alloy；Equal channel angular pressing ；ECAP route ECAP pass；microstructure
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