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济南镀锌管分享焊接过程中注意事项

来源:http://www.jnxxjm.com

【 发布于:2020-06-23 16:47:49 】


镀锌管耐腐蚀,硬度强,是现在常用的输气管设备。关于镀锌管焊接操作性可是要强一些,大家可能掌握起来稍难一些。不过没关系,既然生活常用,了解一下它的焊接知识也是好的。今天济南镀锌管就来跟大家分享镀锌管的焊接注意事项。

Galvanized pipe is corrosion-resistant and hard, which is now commonly used gas transmission equipment. As for the welding operability of galvanized pipe, it's a little more difficult for you to master. But it doesn't matter. Since life is often used, it's good to know about its welding knowledge. Today, Jinan galvanized pipe will share with you the welding precautions of galvanized pipe.

1、焊接前焊缝处必须打磨 必须把焊接处的镀锌层打磨掉,否则会产生气泡、沙眼、假焊等。还会使焊缝变脆,刚性下降。

1. Before welding, the welding seam must be polished and the galvanized layer must be polished off, otherwise bubbles, sand holes, false welding, etc. will occur. It will also make the weld brittle and reduce the rigidity.

2、焊接手法介绍:在焊多层焊的层焊缝时,尽量使锌层熔化并使之汽化、蒸发而逸出焊缝,可大大减少液体锌留在焊缝中。在焊角焊缝时,同样在层尽量使锌层熔化并使之汽化、蒸发而逸出焊缝,其方法是先将焊条端部向前移出约5~7mm左右,当使锌层熔化后再回到原来位置继续向前施焊。再横焊和立焊时,如选用短渣焊条如J427,咬边倾向会很小;如果采用前后往返运条技术,更可以得到无缺陷的焊接质量。

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2. Welding technique introduction: when welding the first layer of multi-layer welding, try to melt the zinc layer and make it vaporize and evaporate to escape from the weld, which can greatly reduce the liquid zinc left in the weld. When welding the fillet weld, the zinc layer shall be melted and vaporized and evaporated in the first layer as much as possible to escape from the weld. The method is to move the end of the electrode forward about 5 ~ 7mm, and then return to the original position to continue welding forward after the zinc layer is melted. If the short slag electrode, such as J427, is used in the cross welding and vertical welding, the undercut tendency will be very small; if the back and forth strip transportation technology is used, the flawless welding quality can be obtained.

3、镀锌钢焊接特点分析。

3. Analysis of welding characteristics of galvanized steel.

镀锌钢一般是在低碳钢外镀一层锌,镀锌层一般在20um厚。锌的熔点在419°C,沸点908°C左右。在焊接中,锌熔化成液体浮在熔池表面或在焊缝根部位置。锌在铁中具有较大固溶度,锌液体会沿晶界深入浸蚀焊缝金属,低熔点锌形成“液体金属脆化”。

Generally, galvanized steel is coated with a layer of zinc outside the low carbon steel, and the galvanized layer is generally 20um thick. The melting point of zinc is 419 ° C and the boiling point is about 908 ° C. In welding, zinc melts into liquid and floats on the surface of the molten pool or at the root of the weld. Zinc has a large solid solubility in iron. The liquid zinc will etch the weld metal along the grain boundary, and the low melting point zinc will form "liquid metal embrittlement".

同时,锌与铁可形成金属间脆性化合物,这些脆性相使焊缝金属塑性降低,在拉应力作用下而产生裂纹。 如果焊接角焊缝,尤其是T形接头的角焊缝更容易产生穿透裂纹。镀锌钢焊接时,坡口表面及边缘处的锌层,在电弧热作用下,产生氧化、熔化、蒸发以至挥发出白色烟尘和蒸汽,极易引起焊缝气孔。

At the same time, zinc and iron can form brittle compounds between metals. These brittle phases can reduce the plasticity of weld metal and cause cracks under tensile stress. If the fillet weld is welded, especially the T-joint fillet weld, it is most likely to produce through cracks. During the welding of galvanized steel, the zinc layer on the groove surface and edge will oxidize, melt and evaporate under the action of arc heat, and even emit white smoke and steam, which will easily cause weld porosity.

4、如何控制镀锌钢焊接工艺?

4. How to control the welding process of galvanized steel?

镀锌钢的焊前准备与一般的低碳钢是相同的,需要注意的是要认真处理好坡口尺寸和附近的镀锌层。为了焊透,坡口尺寸要适当,一般60~65°,要留有一定的间隙,一般为1.5~2.5mm;为了减少锌对焊缝的渗透,在焊之前,可将坡口内的镀锌层清除以后再焊。

The preparation of galvanized steel before welding is the same as that of ordinary low-carbon steel. It is necessary to carefully handle the groove size and nearby galvanized layer. In order to achieve penetration, the groove size shall be appropriate, generally 60 ~ 65 °, with a certain gap, generally 1.5 ~ 2.5mm; in order to reduce the penetration of zinc into the weld, the galvanized layer in the groove can be removed before welding.

在实际监理工作中,采用了集中打坡口,不留钝边工艺进行集中控制,两层焊接工艺,减少了未焊透的可能性。焊条应根据镀锌管的基体材质选用,一般低碳钢由于考虑易操作性,选用J422较为普遍

In the actual supervision work, the centralized beveling and no blunt edge are used for centralized control. The two-layer welding process reduces the possibility of incomplete penetration. The electrode shall be selected according to the base material of galvanized pipe. Generally, J422 is widely used for low carbon steel due to its operability



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