摩托车铝合金件的焊接性研究（本科毕业论文设计）.doc

摘要

本文针对摩托车铝合金车架的可焊性较差，在焊接过程中易产生焊不透、未熔合、夹杂、气孔、热裂纹等缺陷，特别是接头的软化造成母材的浪费和应用的限制等问题，对摩托车车粿@Ｓ玫腖Y12铝合金的焊接工艺进行了研究，为铝合金在摩托车行业中的应用提供了试验依据，对于扩大铝合金的应用具有重要的意义和实际应用价值。
通过一系列的试验，研究了LY12铝合金的焊接工艺，得出焊接接头成型较好的工艺参数。对LY12焊接接头的力学性能（强度、硬度和塑性）进行了测试；然后利用金相显微镜对LY12铝合金焊接接头及其附近区域的显微组织进行了分析；并且对于焊缝的软化和出现裂纹和气孔等缺陷也进行了分析。
通过对LY12铝合金的焊接工艺试验的分析，本文得出：MIG焊的工艺参数对焊缝成形有明显的影响，采用合适的工艺参数可以获得较高质量的焊缝。
通过对LY12焊接接头力学性能、焊缝组织，焊缝缺陷的分析，本文得出：LY12焊接接头的硬度、强度和塑性均低于母材的对应力学性能，且在距焊缝中心约9～13mm处的热影响区发生了软化。软化区产生的主要原因是：该区强化相粒子在焊接热循环过程中发生了过时效，产生聚集粗化。经过一定的自然时效，接头的强度和延伸率有一定的恢复；LY12铝合金具有一定的结晶裂纹敏感性。在MIG焊下，LY12铝合金的气孔敏感性较大，焊接方法、环境相对湿度、试板表面状态、保护气体成分及焊接规范对LY12铝合金的气孔敏感性有很大的影响。通过控制各种水分的来源并采用合适的焊接规范可减小LY12的气孔敏感性。

关键词：LY12铝合金，焊接工艺，显微组织，裂纹，气孔











ABSTRACT

This passage be aimed at the low capability of aluminum alloy of Motorcycle pieces,producing a lot of blemishs in welding process,for example,the welding is not deeply,lard,pore,hot crack and so on ,in particular joints caused a softening of base metal waste and application of restrictions and other issues, Therefore,the article explored the welding technology of LY12 aluminum alloy that is often used in Motorcycle Frame.This research provides experiment data for the application of aluminum alloys in Motorcycle industry. The work also has important practical value and Significance to the further use of aluminum alloys.
The mechanical properties of LY12 welded joint were also tested. In order to make further research of the different performance between welded joint and base metal of LY12 alloy, the microstructure characteristics were studied by means of advanced test methods including optics microscope. Furthermore, the article also covered research of effects about different welding processes and parameters on LY12 alloy bead sizes and the softening and the weld cracks and pore defects also were analyzed.
The result of the LY12's aluminum welding technology test shows that: MIG welding process parameters of the weld have great effect on weld shape, using appropriate technical parameters will get welds of higher quality.
The study of microstructure and properties of LY12 welding joint indicates that hardness, tensile strength and plasticity of the joint are lower than the relevant properties of base metal and the weakest point of welded joint is in the soften zone of HAZ, 9~13mm away from the weld center. It is formed due to the overaging of the main strengthening phase particle, which aggregates and coarsens during the influence of welding heat. After some extent of natural seasoning, tensile strength and plasticity of the joint are restored;LY12 aluminum alloy has a crystal crack sensitivity. In the TIG and MIG welding, LY12 aluminum alloy has larger stomatal sensitivity, and welding method, relative humidity and try to board surface, the protection of welding gas composition and norms of the LY12 aluminum alloy greatly affect stomatal sensitivity .Stomatal sensitivity of LY12 can be reduced by controlling the various water sources and using the appropriate welding standards

Key Words: LY12 alloy, welding technology, microstructure,hot cracking, porosity



目 录

中文摘要 Ⅰ
ABSTRACT Ⅱ
1绪论 1
1.1 课题研究的背景和意义 1
1.2 本课题研究内容 2
2 LY12铝合金的焊接性分析、焊接方法及试验材料的确定 3
2.1 LY12铝合金焊接母材介绍 3
2.2 铝合金焊接方法选择 3
2.2.1国内外铝合金焊接的先进工艺概述 3
2.2.2 铝合金常用焊接方法概述 4
2.3 焊接材料 5
2.3.1焊丝 5
2.3.2保护气体 6
2.4铝合金的焊接性 6
3 LY12铝合金焊接试验 8
3.1焊前清理 8
3.1.1 机械清理 8
3.1.2 化学清理 8
3.2焊接设备 8
3.2.1焊机 8
3.2.2焊接工艺参数 8
3.3焊接测试 9
3.3.1焊接接头试样的切取 9
3.3.2 焊接接头试样的制备 9
3.3.3 测试手段 10
4 实验结果及分析 11
4.1 焊接工艺对LY12铝合金焊缝尺寸的影响 11
4.1.1 MIG 焊焊接参数对角接焊缝尺寸的影响 11
4.1.2 MIG焊焊接参数对搭接焊缝尺寸的影响 12
4.1.3 MIG 焊焊接参数对对接焊缝尺寸的影响 13
4.2 接头力学性能试验 14
4.2.1 接头的拉伸与弯曲试验 15
4.2.2 接头硬度试验 15
4.3 焊接接头组织与性能分析 16
4.3.1 金相分析 16
4.3.2 接头性能分析 17
4.4焊接缺陷的形成机理及防止措施 17
4.4.1 LY12铝合金裂纹敏感性 17
4.4.2 LY12铝合金的气孔敏感性 18
5 结论 21
致谢 22
参考文献 23