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摘要本文对2.5 mm厚的AZ31B镁合金薄板光纤激光焊接工艺进行了试验，采用金相显微镜、X 射线衍射仪、电子万能拉伸试验机等分析手段研究了焊接接头各区域的微观组织、组成成分、接头的拉伸性能、断口形貌特征等。并通过对比接头的形貌、晶相、拉伸断口的形貌从试验中探索AZ31B镁合金的焊接工艺。33712
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研究了工艺参数对焊缝形貌的影响。焊缝宽度随随功率的增大而增大，当达到2 kW—3 kW之间某数值时达到最大后开始降低；焊缝宽度随离焦量变大而变大，但是合金烧损也越加严重。
研究了工艺参数对显微组织和力学性能的影响。薄板镁合金自熔激光焊焊缝的热影响区很小；焊缝成形效果不同的焊缝低倍金相组织差别不大；使用恰当的工艺参数，可以使焊缝的抗拉强度达到母材的83%以上。拉伸断裂方式主要以切断为主，主要原因为微观气孔的生成。
关键词 镁合金 光纤激光焊 工艺参数 微观组织 力学性能
毕业论文设计说明书外文摘要
Title Magnesium alloy experimental study on fiber laser welding technology
Abstract
In this paper,2.5mm of AZ31B magnesium alloy sheets of fiber laser welding technology is tested, using optical microscopy, x-ray diffraction, electronic universal tensile testing machine for welded joints was analyzed by means of research, composition, microstructure, tensile properties and fractographic features of joint, etc. Crystal phase and through comparative morphology of joints, finding their way from the test, tensile fracture morphology of AZ31B magnesium alloy welding process.
Study on influence of process parameters on weld appearance. Welding seam width increases with the increase of power, when when it reaches a value between 2kW--3kW reaches a maximum and then began to decrease; width change larger with defocus quantity become larger, and burn of alloy is more severe.
Study on effect of technology parameters on microstructure and mechanical properties. Magnesium alloy laser welding weld of HAZ is small; weld forming effect different of weld low metallographic organization difference is unlikely to; Use appropriate process parameters can makes weld of tensile strength reached base material of 83% above. Tensile fracture mainly dominated by the form of cut, mainly due to the formation of micro-pores.
Keywords Magnesium alloy fiber laser welding process parameters microstructure mechanical properties
目次
1 绪论 1
1.1 引言 1
1.2 本课题研究目的和意义 1
1.3 镁合金焊接特性及发展现状 1
1.4 本论文研究重点 3
2 实验方案 4
2.1 实验材料 4
2.2 实验仪器 4
2.3 实验工艺 8
2.4 金相组织与力学性能试验 9
3 对接焊接接头形貌研究 10
3.1 焊缝形貌特征 10
3.2 功率对焊缝成形的影响 11
3.3 离焦量对焊缝成形的影响 12
3.4 本章小结 14
4 对接接头显微组织研究 15
4.1 成形良好的焊缝金相组织分析 15
4.2 成形不好的焊缝金相组织分析 18
4.3 本章小结 19
5 对接焊接接头力学性能分析 20
5.1 拉伸性能分析 20
5.2 焊缝显微硬度分析 21
5.3 本章小结 21