China used pipe welding machines often consider many key technologies when producing precision welded pipes, such as ① quality requirements for raw materials.② welded pipe forming process. ③ formation and removal of weld burrs. ④ weld heat treatment. ⑤ non-destructive testing. ⑥ correct Equipment requirements for welded pipe unit. For this reason, we will introduce the quality requirements of raw materials to be considered in the production of precision welded pipes.

Precision welded pipes are more accurate in geometric dimensions than general welded pipes, and the welds and inner and outer surfaces are of good quality, and the wall thickness is uniform. It can be used in equipment components directly or with a small amount of processing. It is widely used in chemical, textile machinery, aviation, instrumentation, automotive and other sectors .

In view of the quality requirements of raw materials for the production of precision welded pipes by China used pipe welding machines: The raw materials of precision welded pipes must meet the basic requirements of ordinary high-frequency electric welded steel pipes, but also meet the following requirements:

①Chemical composition: During smelting, the focus is to improve the purity of steel and reduce the content of non-metallic inclusions in the steel. The sulfur and phosphorus content should be less than 0.03%. In order to adapt to the subsequent cold deformation processing, the sulfur content should not exceed 0.02%, so the chemical composition of steel must be strictly controlled. At the same time, in order to ensure that the product has good mechanical properties, cold bending, welding and other process properties, some elements such as Nb, Ni, and V need to be appropriately added.

②Steel strip shape and size: When steel strip is rolled, AGC and shape control system should be used to improve the thickness accuracy and shape accuracy of the steel strip. At the same time, a controlled cooling method must be used to improve the strength and toughness of the steel strip. The width and dimensional accuracy of the slitting steel strip must be controlled, and the edge of the steel strip must be free of indentations and burrs to improve welding quality.

③Rust on the surface of the steel strip: the yellow rust on the surface of the steel strip is the crystal water of iron oxide. During the welding process of the China used pipe welding machines, the high temperature will cause the oxygen and hydrogen to be folded out. If it cannot be discharged, it will exist in the weld. In the medium, it is easy to produce pores and micro-cracks, change the structure, reduce the plasticity of the material, and reduce the elongation, so it is necessary to avoid the corrosion of the surface of the steel strip.

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