镁合金氩弧焊接接头力学性能研究（本科毕业论文设计）.doc

摘 要

随着镁合金应用的日益广泛，其焊接接头的力学性能也越来越受到人们的重视。当前，国内外对镁合金焊接技术的研究已经取得了较大的进展，各种先进的焊接技术日益完善，为镁合金焊接技术的发展提供了广阔的前景。
本文采用钨极氩弧焊（TIG）对AZ61镁合金进行焊接试验，并对它们的焊接接头试样作了微观组织观察和试样拉伸试验，分析了各种焊接因素（焊接电流、焊接速度、有无填焊丝等）对焊缝成型和焊接质量的影响及其规律。利用金相显微镜、电子扫描显微镜、万能材料试验机、X射线衍射仪等设备对焊接接头显微组织、焊缝相分布、接头力学性能等进行了分析，并对焊接过程中气孔和裂纹产生的原因和防止措施进行了讨论。试验结果表明：镁合金氩弧焊的焊接工艺条件对焊缝表面形状及焊缝成型质量有很大影响；而焊缝的质量又直接影响着镁合金焊接后的力学性能。


关键词：镁合金，氩弧焊，焊缝，力学性能，缺陷


















ABSTRACT

The mechanical property of welding magnesium alloy is one of the major concerns in the development of magnesium alloy be used in industry. Recently, research on the welding of magnesium alloy makes a great progress and the new advanced welding techniques which be used in industry promoted the further development of magnesium alloy welding techniques.
In this study, the influence of gas tungsten arc (TIG) welding parameters (such as welding current, welding speed and welding wire) on the microstructures and mechanical properties of AZ61 magnesium alloy welded joints was investigated. Microstructure was characterized by optical microscopy and scanning electron microscopy. X-ray diffraction was adopted for the determination of phase structure in alloy. Mechanical properties were determined by standard tensile tests. Furthermore, the intrinsic mechanism of the formation of porosity and cracking in welded joints was discussed in detail. The results indicate that the formation of welding seam and their qualities were influenced by the welding parameters, and then the achieved welding seam influenced the mechanical properties of magnesium alloy welding joint strongly.


Key words：magnesium alloy, TIG, welding seam, mechanical properties, welding defects














目 录

中文摘要 Ⅰ
ABSTRACT Ⅱ
1绪论 1
1.1镁合金的性能及应用 1
1.2镁合金的焊接 2
1.2.1 镁合金的焊接特性 2
1.2.2 镁合金氩弧焊(TIG)及其特点 3
2 实验 6
2.1 实验材料 6
2.2 工艺方案 6
2.3 实验设备及其原理 7
2.3.1 扫描电子显微镜 7
2.3.2 万能材料试验机 9
2.4 实验方法 10
2.4.1 试样制备 10
2.4.2 实验步骤 11
3 实验结果及分析 12
3.1镁合金氩弧焊焊接接头的微观组织观察 12
3.1.1 AZ61镁合金焊接接头微观组织 12
3.1.2 焊接工艺对接头组织与性能的影响 15
3.1.3 焊缝成分分析 18
3.2 AZ61镁合金氩弧焊接头焊接缺陷的分析 20
3.2.1 气孔 20
3.2.2 裂纹 22
3.3氩弧焊接接头的力学性能分析 23
3.2.1焊接接头显微硬度测试及分析 23
3.2.2焊接接头拉伸力学性能分析 23
4 结论 26
参考文献 27