基于EBSD的热轧工艺参数对近共晶Al-Si合金动态再结晶的影响

论文总字数：35025字

摘 要

近共晶 Al-Si-Mg合金具有铸造性能好、强度高、成本低等优点，同时拥有良好的热变形成形能力，通过适当的变形热处理后可以达到强度和塑性的良好结合，具有成为铝型材的巨大潜力。所以本文以近共晶Al-Si-Mg 合金作为对象，基于EBSD观察研究热轧制工艺对近共晶 Al-Si-Mg 合金组织的影响。取得了以下主要结果：

在压下率为 33%的条件下，当轧制温度从 500 ^o C 提升为 540 ^o C时，织构类型未发生明显变化，但大角晶界分数显著提高、平均晶粒尺寸变小，再结晶程度明显增加，因而伸长率却提升了22%，然而合金的屈服强度和抗拉强度没有发生太大变化。

在 500^oC轧制温度下，随着压下率从 33%升高至 67%，合金组织中织构发生了显著的改变，从以形变织构为主转变成以再结晶织构为主，同时大角晶界分数显著提高、平均晶粒尺寸显著变小，再结晶程度明显增加，因而伸长伸率大幅度升高。但合金的屈服强度小幅度降低，其主要原因是：一方面Mg ₂ Si相的动态析出也随之增大，导致基体软化；另一方面，Al基体动态再结晶更充分成熟，再结晶软化也增强。

关键词：近共晶铝硅镁合金；热轧制工艺；EBSD；显微组织；力学性能；动态再结晶；

Abstract

Near eutectic Al-Si-Mg alloy has good casting properties, high strength, low cost advantages, has good capability of heat deformation forming at the same time, through the proper deformation after heat treatment can achieve good combination of strength and plasticity, has the huge potential of aluminum. So this article near eutectic Al-Si-Mg alloy as object, based on the EBSD study hot rolling technology of nearly eutectic Al-Si-Mg the influence of the Mg alloy organization. Made the following main results：

Under the condition of press down at a rate of 33%, when the rolling temperature increase from 500^oC to 540^oC, texture types did not change significantly, but the big Angle grain boundary fraction increased significantly, the average grain size smaller, recrystallization was significantly increased, thus elongation were increased by 22%, the yield strength and tensile strength of the alloy, however, were not change too much.

When the rolling temperatur is 500 ^oC, as the pressure rate increased from 33% to 67%,microstructure of a significant change in texture, shift from predominantly deformation texture to give priority to with recrystallization texture, large Angle grain boundary fraction increased significantly at the same time, the average grain size was significantly smaller, recrystallization was significantly increased, and thus elongation rate significantly increased. But the lower yield strength small range alloy, its main reason is: on the one hand, precipitation of Mg₂Si phase dynamic also increase, lead to soften matrix; The Al substrate, on the other hand, the dynamic recrystallization more fully mature, recrystallization softening are also enhanced.

Keywords: nearly eutectic aluminum silicon magnesium alloy; EBSD; microstructure; mechanical properties; Hot rolling ;dynamic recrystallization；

目录

摘要 ..................................................................................................................................................... I

Abstract ................................................................................................................................................ II

目录 .....................................................................................................................................................III

第一章 绪论 .................................................................................................................................... 1

1.1 引言 ................................................................................................................................... 1

1.2 铝合金形变热处理 ............................................................................................................1

1.3 铝合金中的动态再结晶研究 ............................................................................................2

1.3.1 动态回复 .................................................................................................................2

1.3.2 动态再结晶机制 .................................................................................................. . 2

1.3.3 影响动态再结晶的因素 ........................................................................................ 3

1.4 利用EBSD技术对铝合金进行研究............................................................................. ..... 4

1.5 选题的背景以及意义 ........................................................................................................5

1.6 研究内容与技术路线 ..................................................................................................5

1.6.1 研究内容 .......................................................................................................... ..... 5

1.6.2 技术路线 .................................................................................................................6

1. 合金制备与实验方法 ....................................................................................................... .7

2.1 合金选择与成分设计................................................................................................. 7

2.2 合金的熔炼工艺..........................................................................................................8

2.3热轧制工艺.................................................................................................................. 8

2.4 热处理工艺................................................................................................................. 8

2.5 室温拉伸性能测试......................................................................................................8

2.6 电子背散射衍射（EBSD）观察 ............................................................................... 9

1. 热轧制工艺对Al-Si-Mg合金组织与力学性能的影响 ..................................................11

3.1 热轧制温度对Al-Si-Mg合金组织与力学性能的影响 ...................................................11

3.1.1 热轧制温度对Al-Si-Mg合金组织的影响 ....................................................11

3.1.2 热轧制温度对对Al-Si-Mg合金力学性能的影响 ................................................13

3.2 热轧制压下率对Al-Si-Mg合金组织与力学性能的影响 ...............................................16

3.2.1 热轧制压下率对Al-Si-Mg合金组织的影响 ................................................16

3.2.2 热轧制压下率对对Al-Si-Mg合金力学性能的影响 ............................................18

1. 结论与展望 ..................................................................................................................... 20

参考文献 ......................................................................................................................................... 22

致谢 ......................................................................................................................................... 26

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