变形镁合金变热处理的研究.doc

大连理工大学本科毕业设计（论文） 变形镁合金形变热处理的研究 The research of distortion magnesium alloy after heat deformation treatment 学 院（系）： 材料科学与工程学院 专 业： 金属材料工程 学 生 姓 名： 学 号： 指 导 教 师： 评 阅 教 师： 完 成 日 期： 大连理工大学 Dalian University of Technology 摘 要 镁及镁合金是目前最轻的金属结构材料，具有密度低、比强度和比刚度高、阻尼减震性好、导热性好、电磁屏蔽效果佳、机加工性能优良、零件尺寸稳定、易回收等优点，在航空航天、汽车、计算机、电子、通讯和家电等行业有着广泛的应用前景。 镁合金具有较好的铸造性能，目前镁合金产品以压铸件居多，但与铸造镁合金相比，变形镁合金晶粒细小，成分偏析低，具有较好的强度和塑性，是性能优良的镁合金，因此，镁合金塑性成形工艺的研究已成为世界镁工业中重要的方向。由于镁合金密排六方的晶体结构，常温下塑性变形能力较差，加工成品率低，限制了其应用。随着温度升高，原子振动幅度增大，会激活潜在的滑移面和滑移方向，使变形镁合金塑性性能大大改善。 本文从提高镁合金性能入手，将AZ31和AZ61挤压变形镁合金进行不同条件的热处理，研究T4处理、T5处理和T6处理对挤压变形镁合金显微组织和硬度的影响，结果表明：AZ31镁合金在350℃固溶12h下得到了较优化的热处理工艺的组合，AZ31镁合金硬度值达到65.5 HB。AZ61镁合金在200℃ 时效12h下得到了较优化的热处理工艺的组合，AZ61镁合金硬度值达到70.0HB。 关键词：AZ31镁合金；AZ61镁合金；热处理；显微组织；力学性能  The research of distortion magnesium alloy after heat deformation treatment Abstract Magnesium and magnesium alloy are the lightest metallic structural material at present. They have been used widely in the aviation, automotive, computer, and electronics industries, due to their unique properties such as low density, high specific strength and rigidity, good damping capacity and heat conductivity, excellent electromagnetic shield effectiveness and machinability, good dimensional stability and recycle character, and so on. Because of the close grain, low composition segregation and high strength and plasticity, wrought Mg alloy has better properties than cast Mg alloy. But Mg alloy is the HCP crystal structure, therefore its plastic deformation is worse at room temperature, and processed yield is also lower, which could be limit its application. The plasticity of wrought Mg alloy will be greatly improved with higher temperature. The behavior of pyroplastic deformation of AZ31 alloy was systematically studied with optical microscope and SEM. Physics and numerical simulation technique such as Gleeble-1500 thermal analog comp