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激光束的入射方向及入射角度会直接影响焊缝熔池的形状及其流动形态，这会对焊缝成型与性能产生重要影响。

为了了解激光束与焊缝的相对位置对焊缝的影响，我们做了两次实验，分别用非高反材料和高反材料进行测试。

本期【Rayclass | 锐课堂】首先来看看高功率多模组连续激光器RFL-C4000（纤芯100μm）在焊接非高反材料（不锈钢为例）时受激光束入射相对位置对焊缝的影响规律。

1）

试验材料  

Experiment Material

6mm厚的304不锈钢

6mm thick 304 stainless steel

2）

试验设备

Experiment Equipment

4000W多模组连续光纤激光器（配备100μm芯径的光纤）、悬臂式焊接工作台、焊接头（准直镜焦长100mm，聚焦镜焦长300mm）

4000W multi-module CW fiber laser (with 100μm core fiber), cantilever welding table, welding head (100mm collimator lens focal length, 300mm focusing lens length)

 

3）

试验方法

Experiment Method

首先用300W高功率脉冲光纤激光器，将待焊材料表面的氧化层及油污去除；

Firstly, the oxide layer and oil stain on the surface of the material to be welded are removed by using a 300W high power pulsed fiber laser. 

 

随后，将两种材料进行堆焊。

then, the two materials were bead welding.

4）

试验过程

Experimental Procedure

按照设定好的参数进行焊接试验，试验参数如下表所示，试验完成后对试板进行线切割取样，然后进行金相制取并检测分析。

The welding test is carried out according to the set parameters. The test parameters are shown in the following table. After the test is completed, the test plate is subjected to wire cutting sampling, and then the metallographic preparation is carried out and tested.

 

表1中所谓的光束入射方向表述是相对于焊接方向进行确定的，如图1所示，

The so-called beam incidence direction expression is determined relative to the welding direction.

 

 

图1 激光束入射方向

Graph 1. Laser beam incident direction

光束入射角度表述为激光束与试板法线的夹角，如图2所示。

As shown in Graph 2, the angle of incidence of the beam is expressed as the angle between the laser beam and the normal of the test plate.

 

5）

试验结果

Experiment Result

不锈钢304的焊接试验检测结果如下表所示。

The welding test results of 304 stainless steel are shown in the following table.

 

 

 

 

（图中横坐标数值表示光束入射角度值，“负值”表示光束前倾，“正值”表示光束后倾）

Graph 3 Effect of beam position on penetration and melting width when welding aluminum alloy

(the abscissa value indicates the incident angle of the beam, the negative value indicates the forward tilt of the beam, and the positive value indicates the backward tilt of the beam.)

从表2和图3可以看出，激光垂直入射焊接时的焊缝熔深最大，光束入射角度越大，熔深越浅，并且在同一入射角度时光束前倾相对于光束后倾的熔深略小。

It can be seen from Table 2 and Graph 3 that the weld penetration is maximum when laser perpendicular incidence welding. Meanwhile, the larger the incident angle of the beam, the shallower the penetration, and at the same angle of incidence, the depth of fusion of beam forward is slightly smaller than beam backward.

有学者郭鸿鹏对此进行了深入研究，其主要结论可阐述为:主要是因为光束射入焊缝形成小孔效应时，因液态金属受向外喷发的金属蒸汽羽的反作用力而流动：当光束垂直入射时，该反作用力几乎是垂直向下将液态金属推向熔池底部；当光束前倾时，该反作用力方向趋于水平，并且当倾角越大时，该反作用力方向越趋于水平，如图4（a）所示，使熔池头部的液态金属流向熔池尾部，熔池底部的液态金属因为摩擦力的作用而向上流动；当光束后倾时，该反作用力方向是垂直于小孔前壁斜向下，如图4（b）所示，所以有垂直向下的分力作用于熔池顶部的液态金属，使其向下流向熔池底部，同时当倾角越大时，小孔前壁越陡峭，该反作用力方向越趋于水平，其垂直向下的分力就会越小。

Some scholars have studied the phenomenon of this result that when the beam is injected into the weld to form a small hole effect, the liquid metal flows due to the reaction force of the outwardly ejected metal vapor plume. When the beam is incident vertically, the reaction force pushes the liquid metal toward the bottom of the molten pool almost vertically downwards. When the beam is tilted forward, the direction of the reaction force tends to be horizontal, and when the angle of inclination is larger, the direction of the reaction force tends to be horizontal. As shown in Graph 4(a), the liquid metal at the head of the molten pool flows toward the tail of the molten pool, and the liquid metal at the bottom of the molten pool flows upward due to the frictional force. However, when the beam is tilted backward, the direction of the reaction force is perpendicular to the front wall of the small hole. As shown in Graph 4(b), there is a vertical downward component acting on the liquid metal at the top of the molten pool, causing it to flow down to the bottom of the pool. At the same time, the larger the inclination angle, the steeper the front wall of the small hole, the more the direction of the reaction force tends to be horizontal, and the smaller the vertical downward force component will be.

熔池中的液态金属均是高温状态，具有较大的热量，进入熔池底部的液态金属越多，就会带入越多的热量至熔池底部，从而使其能够更多的通过热传导方式熔化更多的熔池底部边缘的母材金属，进而增大焊缝熔深。液态金属受到的向熔池底部方向的力越大，就会有越多的液态金属流入熔池底部，就会产生更大的熔深，所以就会出现上述图3中熔深曲线所表明的现象。

The liquid metal in the molten pool is at a high temperature and has a large amount of heat. The more liquid metal that enters the bottom of the pool, the more heat it carries into the bottom of the molten pool. Therefore, it can more melt the base metal of the bottom edge of the molten pool by heat conduction, thereby increasing the weld penetration. The greater the force that the liquid metal receives in the direction toward the bottom of the molten pool, the more liquid metal will flow into the bottom of the pool. It will produce a larger penetration, so the phenomenon indicated by the penetration curve in Graph 3 above will occur.

 

 

图4 液态金属在不同光束位置时的受力状态

Graph 4. Force state of liquid metal at different beam positions

从表2中不锈钢焊缝横截面金相和焊缝表面成型来看，光束倾角大小及方向对焊缝气孔的产生几乎没有影响，均可得到无气孔的焊缝，但是光束倾角大的时候焊缝成型均匀性会相对差一些，这可能是因为光束倾角较大时，焊缝熔池金属的流动状态发生了较大改变，容易出现不稳定的状态。

From the perspective of the metallographic and weld surface of the stainless-steel weld cross section in Table 2, the size and direction of the beam inclination have hardly any effect on the generation of weld porosity, and a weld without voids can be obtained. But the uniformity of weld formation will be relatively poor when the beam angle is large. This may be because when the beam inclination angle is large, the flow state of the weld pool metal changes greatly, and it is prone to unstable state.

6）

结论

Conclusion

I）不锈钢激光自熔焊时，激光束垂直入射的焊缝熔深最大，光束入射角度越大，熔深越浅，并且在同一入射角度时光束前倾相对于光束后倾的熔深略小；

When single laser welding stainless steel, the depth of weld joint is the greatest when laser beam is incident vertically. Meanwhile, the larger the beam incidence angle, the shallower the fusion depth. And at the same incident angle, the fusion depth of the forward dip is slightly smaller than the backward dip of the beam.

II）不锈钢激光自熔焊时，激光束入射倾角大小及方向对焊缝气孔的产生几乎没有影响，均可得到无气孔的焊缝，但是光束倾角大时焊缝成型均匀性会相对差一些。

When single laser welding stainless steel, the angle and direction of the incident angle of the laser beam have almost no effect on the generation of weld porosity, and a weld without voids can be obtained. However, the uniformity of weld formation will be relatively poor when the beam angle is large.

看完了4000W连续光纤激光器（纤芯100μm）在焊接非高反材料时受激光束入射相对位置对焊缝的影响规律测试后，您是否也想知道，对于高反材料这种结论是否也同样适用？