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摘要本文对AZ61M镁合金进行固溶处理，得到的最佳的固溶工艺参数。在最佳的固溶工艺下进行380℃的多向锻造，对多向锻造后的试样进行了金相观察和力学性能的测试。由于铸态材料中沿晶界分布的粗大网状第二相严重影响了材料的强度和延伸率，因此要进行固溶处理使得第二相溶解入基体中。400℃、2h固溶后，第二相大量溶解入基体中，此时第二相对材料的力学性能起到了强化作用，又由于固溶强化，因此抗拉强度由铸态的185Mpa提高到250Mpa，延伸率由6.4%提到到7.1%；固溶4h后第二相基本溶解入基体中，此时第二相强化作用消失，但固溶强化作用增强，因此抗拉强度降低到230Mpa，而延伸率进一步提高到10.2%；固溶6h后剩余第二相与固溶4h后剩余第二相相差不大，而晶粒尺寸长大了很多，达到89μm，相对于固溶4h状态其抗拉强度降低到208Mpa，延伸率降低到8.3%。20885
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多向锻造一道次后，坯料的微观组织中出现了较多细小的动态再结晶晶粒，平均晶粒尺寸也有所降低，达到37μm，抗拉强度达到200.5Mpa，延伸率达8.2%。多向锻造二道次后，动态再结晶晶粒体积分数增加，平均晶粒尺寸进一步降低到31μm，坯料的抗拉强度进一步提高到320.8Mpa，延伸率进一步提高到12.5%。
关键词：AZ61M镁合金、热成形、多向锻造、微观组织、力学性能
毕业论文设计说明书（论文）外文摘要
Title Hot formation of Mg alloy with high strength
Abstract
In this article,AZ61M Mg alloy was carried under solid solution treatment to achieve the best parameters. After solid solution treatment of the best parameters, the workpiece was multi directional forged at 380℃.After the multi directional forging, microstructure of the workpiece was observed and mechanical properties of the workpiece were tested.
Since the coarse net-like β phase in the as-cast AZ61M Mg alloy affects the tensile strength and elongation of the material severely, solid solution treatment was carried on to get β phase solute into the matrix. After solid solution at 400℃ for 2h,lots of β phase is solute into the matrix ,the rest of β phase strengthens the matrix and solid solution strengthens the matrix as well.The tensile strength raise to 250Mpa from 185Mpa of as-cast state ,and also the elongation of the 2h state increase to7.1% from 6.4% of as-cast state. After solid solution at 400℃ for 4h,just little β phase remains .in this case, β phase strengthening no longer exists but solid solution strengthening is reinforced, therefore the tensile strength decrease to 230Mpa but the elongation increase to 10.2%.After solid solution at 400℃ for 6h,the rest of β phase is similar to that under solid solution at 400℃ for 4h.In addition, the size of the grain grows fast to approximately 89μm. Comparing to solid solution for 4h,the tensile strength decrease to208Mpa and the elongation decrease to 8.3%.
After multi directional forging pass 1,the microstructure of workpiece shows lots of dynamic recrystal grains. Average grain size decrease to 37μm and tensile strength increase to 200.5Mpa.Also the elongation increase to 8.2%. After multi directional forging pass 2,the microstructure of workpiece shows more dynamic recrystal grains in volume fraction. Average grain size decrease to 31μm and tensile strength increase to 320.8Mpa.Also the elongation increase to 12.5%.
Keywords: AZ61M Mg alloy、 hot formation 、multi directional forging 、microstructure、mechanical properties
目 次
1 绪论 1
1.1 镁合金及其研究现状 1
1.2 镁合金的热成型 7
1.3 Deform-3D有限元分析 10
1.4 课题研究的目的、意义与研究内容 10