摘要近年来，镁合金由于其密度小，比强度和比刚性高等一系列优点，备受关注， 其应用领域已涉及汽车、航空、航天等诸多方面。但由于其为密排六方结构，在 室温下滑移系少，塑性差，导致其较难进行塑性加工（如冲压）。因此，研究成 形温度、晶粒尺寸对于镁合金胀形性能的影响，对改善和加强镁合金的应用具有 重要的意义。

本文选用 AZ31 镁合金轧制板料为研究对象，改变退火温度和保温时间，对 AZ31 镁合金轧制板料进行退火实验。通过 Erichsen 胀形实验和金相试验研究了 不同晶粒尺寸和变形速率下 AZ31 镁合金板的胀形性能及胀形过程中的微观组织 变化。

研究结果表明，在胀形过程中，板料的减薄区最严重的位置在距离球形冲头 中心 1/3 半径处，并且该区域也是裂纹出现的位置。通过胀形试验发现，不同退 火温度和退火时间对于 AZ31 镁合金板料的影响是不一样的。退火温度为 300oC 和 350oC，板料的 Erichsen 值随着退火时间的延长而增加；而在退火温度为 400oC 条件下，Erichsen 值随着退火时间先降后升再降。此外，镁合金板料在经过胀形 试验后，观察其金相组织，发现组织中有孪晶出现，且 Erichsen 值较高的板料， 其组织中孪晶数量较多。因此，孪晶的出现有利于板料胀形性能的改善。

毕业论文关键词 AZ31 镁合金 塑性 成形工艺 胀形

Title The research of bulging performance forAZ31 magnesium alloy sheet

Abstract

In recent years, the researcher are focus on magnesium alloys because of its small density ,high specific strength and specific stiffness and a series of  advantages, and already applied in various industries, such as automotive, aviation, aerospace and other industrial fields. At room temperature, slip system of magnesium and magnesium alloys is less because of their typical hexagonal close-packed crystal structure, lead to low plasticity and plastic processing difficult. Therefore, it is significant to improve and strengthen the application of magnesium alloy that studying the effects of forming temperature grain size on magnesium alloy bulging performance.

This article selects the AZ31 magnesium alloy rolling sheet as the research subject and magnesium alloy sheet annealing experiments is adopting the conditions of different temperature and time to get different grain size sheet. By Erichsen bulging experiment and metallographic test, we study the change of bulging properties and the microstructure in the process of bulging under different grain size and strain rate of AZ31 magnesium alloy sheet.

The results show that the thinning area of metal sheet is at distances from the center of the spherical punch 1/3 radius in the bulging process, and is also the location of the crack appears in the area. By the bulging experiment, it is found that the influence of different annealing

temperature and time for AZ31 magnesium alloy sheet are not the same. When

the annealing temperature is 300oC and 350oC, Erichsen value of metal sheet is increases with annealing time. And under the condition of the annealing temperature is 400oC, Erichsen value is rise and fall after fall first as the annealing time. In addition, the sheet microstructure after bulging

crystal twinning ,and the number of crystal twinning is more in the higher

Erichsen value sheet. So it can confirm that the emergence of the crystal twinning is helpful for the improvement of the sheet bulging performance.

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