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济南镀锌管在焊接工艺时如何才能达到合理?

来源:http://www.jnxxjm.com

【 发布于:2019-03-18 16:39:12 】


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。

The galvanized layer at the welding site must be polished, otherwise air bubbles, trachoma and false welding will occur. It will also make the weld brittle and reduce the rigidity.

镀锌钢的焊接特点

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”。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形接头的角焊缝容易产生穿透裂纹。

Galvanized steel is usually coated with zinc outside the low carbon steel, and the galvanized layer is usually 20 um thick. The melting point of zinc is 419 degree C and the boiling point is about 908 degree 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 high solid solubility in iron. The liquid zinc will deeply etch the weld metal along the grain boundary, and the low melting point zinc will form "liquid metal embrittlement". At the same time, zinc and iron can form intermetallic brittle compounds. These brittle phases reduce the plasticity of weld metal and cause cracks under tensile stress. If the fillet weld, especially the fillet weld of T-joint, is most likely to produce penetrating cracks.

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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。由于氧化而形成的ZnO,其熔点较高,约1800°C以上,若在焊接过程中参数偏小,将引起ZnO夹渣,同时。由于Zn成为脱氧剂。产生FeO-MnO或FeO-MnO-SiO2低熔点氧化物夹渣。其次,由于锌的蒸发,挥发出大量的白色烟尘,对人体有刺激、伤害作用,因此,必须把焊接处的镀锌层打磨处理掉。

When galvanized steel is welded, the zinc layer on the groove surface and the edge produces oxidation, melting, evaporation and even evaporation of white fume and vapor under the action of arc heat, which easily causes weld pore. The melting point of zinc oxide formed by oxidation is higher than 1800 C. If the welding parameters are too small, it will cause zinc oxide slag inclusion, and at the same time. Because zinc becomes a deoxidizer. FeO-MnO or FeO-MnO-SiO_2 low melting point oxide slag is produced. Secondly, due to the evaporation of zinc, a large amount of white smoke is volatilized, which has stimulating and harmful effects on human body. Therefore, it is necessary to polish the galvanized layer at the welding site.

焊接工艺控制

Welding process control

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 common low carbon steel. It should be noted that the groove size and the galvanized layer nearby should be carefully handled. In order to penetrate, the groove size should be appropriate, generally 60-65 degrees, leaving a certain gap, generally 1.5-2.5 mm. In order to reduce the penetration of zinc into the weld, before welding, the galvanized layer in the groove can be removed and then welded.

在实际工作中,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。焊条应根据镀锌刚管的基体材质选用,一般低碳钢由于考虑易操作性,选用J422较为普遍。

In practical work, centralized grooving without blunt edge is adopted to centralize control, and two-layer welding process reduces the possibility of non-penetration. Welding rod should be selected according to the base material of galvanized rigid pipe. J422 is a common choice for low carbon steel due to its easy operation.

焊接手法: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。

Welding manners: When welding the first layer of multi-layer weld, try to make the zinc layer melt and vaporize and evaporate out of the weld, which can greatly reduce the liquid zinc left in the weld. When fillet weld is welded, the zinc layer is melted in the first layer and vaporized and evaporated to escape from the weld. The method is to move the end of the electrode forward about 5-7 mm, and then to continue to weld when the zinc layer is melted back to its original position. If short slag electrode such as J427 is used in cross welding and vertical welding, the undercut tendency will be very small; if the front and back transport rod technology is used, the defect-free welding quality can be obtained.

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This article is provided by Jinan galvanized pipe. Our website is: http://www.jnxxjm.com. We will provide you with high quality service with wholehearted enthusiasm. Welcome to visit!



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