摘要:激光填丝焊具有高精度、高效率、低变形、高质量的优点，但由于额外焊丝的加入，激光与焊丝的相互作用十分复杂，对焊丝熔入行为的研究具有重要意义。

本实验利用高速摄影技术，在不同工艺参数下，对Q345E低碳钢进行了平板堆焊试验，研究激光功率、光丝间距、送丝速度、离焦量对焊缝形状几何参数以及熔滴过渡的影响，确定了优化的工艺参数，对SMA490BW耐候钢进行了平板对接试验，并进行了组织以及力学性能分析。

研究发现随光丝间距的提高，熔滴过渡行为可分为铺展过渡、液桥过渡和大滴过渡，其中液桥过渡最为稳定。工艺参数对焊缝形状的几何参数有很大的影响，激光功率增加，熔深、熔宽增加；送丝速度增加，熔深变浅，余高增加；光丝间距增大，熔深有变浅的趋势；正负离焦量绝对值相同时，焊缝形状几何参数大致相同。SMA490BW耐候钢激光填丝焊焊接接头组织焊缝区为珠光体加贝氏体，热影响区为贝氏体、铁素体和珠光体的混合物，母材为铁素体加珠光体。焊接接头力学性能良好，强度、塑性较高。

关键字：激光焊接；填充焊丝；熔滴过渡；焊接参数

Abstract:The laser welding with filler wire has the advantages of high precision, high efficiency, low distortion, high quality, but due to the addition of extra wire, the interaction between laser and wire is very complex. It is important to study the welding behavior of the welding wire

Under different process parameters, this experiment using high-speed photography, the welding test of Q345E low carbon steel, the effects of laser power, light wire spacing, wire feeding speed and defocus on the geometric parameters of weld shape and the influence of droplet transfer, optimization of process parameters were determined, the butt of SMA490BW heat-resistant test steel were studied, and the analysis of the microstructure and mechanical properties.          

It is found that the droplet transition behavior can be pided into spreading transition, liquid bridge transition and large droplet transition with the increase of the spacing of the filaments. The liquid bridge transition is the most stable. There is great influence of geometric parameters of process parameters on the weld shape, the increase of laser power, weld depth and weld width increases; wire feeding speed increases, the penetration depth becomes shallower, more than high increase; the filament spacing increases, the penetration depth is shallow trend; negative defocus absolute value at the same time, Weld Geometry roughly the same parameters. The microstructure of welded joint of SMA490BW heat-resistant steel filler wire is pearlite and a small bainite. The heat affected zone is a mixture of bainite, ferrite and pearlite, and the base metal is ferrite and pearlite. The mechanical properties of welded joint are good, the strength and plasticity are higher.          

Keywords: laser welding; filler wire; droplet transfer; welding parameters                

目  录

第一章 绪论 1

1.1 研究背景和意义 1

1.2 激光填丝焊的国内外研究现状 3

1.2.1 激光填丝焊的国外研究现状 3

1.2.2 激光填丝焊的国内研究现状 5

1.3 本文的主要研究内容 6

第二章 试验材料、设备及方法 8

2.1 试验材料 8

2.2 试验设备 8

2.2.1 高速摄影设备 8

2.2.2 焊接机器人 9

2.2.3 激光器 10

2.3 试验方案 11

2.3.1 显微组织分析 11

2.3.2 拉伸与弯曲性能测试 12

2.3.3 显微硬度测试 13

第三章 激光填丝焊的工艺试验以及理论分析 14

3.1 前言 14

3.2 激光功率的影响 15

3.2.1 激光功率对焊缝成形的影响 15

3.2.2 激光功率对熔滴过渡的影响 17