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镁合金温热特性研究

Research on the Properties of Warm Heating of Magnesium Alloy

【作者】 杨亚琴

【导师】 李保成;

【作者基本信息】 中北大学 , 材料加工, 2006, 硕士

【摘要】 变形加工镁合金的研究为材料领域的研究热点之一。镁合金由于其结构的原因,常温下塑性较差,其成形工艺应在高温条件下进行,所以,研究变形镁合金高温下的变形行为和力学性能,对制定和认识成形工艺具有重大意义。本文通过热模拟压缩实验研究了在不同变形温度和不同变形速率下变形镁合金AZ31 和 ZK60 的成形性能和组织变化,并对压缩试样进行了硬度分析。实验结果表明 ZK60 和 AZ31 的热模拟曲线形式并不相同。AZ31 镁合金的热变形属动态再结晶型,材料可以连续变形;ZK60 的热模拟曲线大部分具有一种明显特征,即当应变量为 0.2 附近时达到了峰值应力,之后应力急剧下降并下降到最低值,说明试样形状发生了破坏,且在对应的压缩试样上出现了裂纹。通过分析得出 AZ31 和 ZK60 变形参数的优化组合,且得出 ZK60 比较合理的变形温度是 200℃和 400℃,对变形镁合金压力加工的工艺选择具有重要指导意义。热模拟试样的硬度实验结果表明 AZ31 和ZK60 硬度变化规律不同,AZ31 由于第二相比较少,随变形温度升高硬度降低;但是ZK60 在 200℃、250℃硬度较低,并且在 250℃达到最低点,原因是在此阶段加工硬化作用不明显,而试样的动态再结晶的影响却较大,由热模拟曲线可看出,ZK60 在(250℃、1s-1)时呈现动态再结晶特点。并通过对金相组织的分析,得出孪晶是镁合金塑性变形的主要特征。

【Abstract】 It’s one of the hot spot on the material field that the research on the plastic deformationof magnesium alloys. As it’s structure, magnesium alloy has the smaller plastic deformation atthe normal atmospheric temperature and it’s forming technology should be proceeded at thehigher temperature. It’s has the most important significance of the formulation and theunderstanding of the forming technology of magnesium alloy by researching the magnesium’sbehavior on the deformation and it’s mechanical property.The formability and structure evolution were investigated by thermal simulationcompressing test that AZ31 and ZK60 wrought magnesium alloys were deformed at differenttemperature and speed rate. After the test the hardness analysis was done to the compressedtest samples.The results indicate that the thermal simulation curves of AZ31 and ZK60 have differentforms. The curve of AZ31 has the character of dynamic recrystallization and the materialcan be deformed successive, while most curves of ZK60 have the other obvious character thataround 0.2 in strain the stress reachs the peak and declines rapidly afterwards and lands thelowest. The decline of the curve illustrates the test sample has been destroyed and the cracklecan be found on the test samples correspondingly. After the analysis of the results can receivethe optimized composite of the deformed parameters and get the reasonable deformedtemperatures are 200℃ and 400℃, which can play a directing role in determing thedeforming technology of wrought magnesium alloys. From the hardness of the thermalsimulation test samples can include that the variation laws of the hardness of AZ31 and ZK60are different. The hardness of AZ31 declines by increasing in temperature as it has less secondphase. ZK60 has the lower hardness at 200℃ and 250℃ and reachs the lowest at 250℃with the more obvious effect of dynamic recrystallization on the test samples and the lesseffect of hardened at the stage. It can also be found from the curve of thermal simulation thatZK60 has the character of dynamic recrystallization under 250℃ and 1s-1. The twin crystal isthe main plastic deformation property of magnesium alloy can be concluded from the analysisof the metallographic microstructure.

  • 【网络出版投稿人】 中北大学
  • 【网络出版年期】2006年 08期
  • 【分类号】TG113.2
  • 【被引频次】5
  • 【下载频次】212
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