Straight Seam Steel Pipe Purity Improvement

High frequency welded pipe flattening cracking is caused by welding micro cracks, hard and brittle phase inclusions, coarse grain-like structure, etc.

In order to control the welding seam well, the concept of welding inclusion crack index is proposed. Mainly caused by insufficient welding strength, toughness or ductility. When there are small inclusions in the seam welding that affect the impact toughness, only when the two opposite walls of the steel pipe are flattened to close to the iron box, the weld crack may occur. It is necessary to reduce the cracking of the weld, improve the toughness of the weld, and reduce the inclusions in the weld. So how to reduce the inclusions in the weld?

First, we must improve the purity of raw materials, reduce the content of P and S, and reduce the content of inclusions. Secondly, check whether the edge of the steel belt is scratched, whether it is stained with rust or dirt, which is not conducive to the discharge of molten metal, and it is easy to cause weld inclusions. Thirdly, uneven wall thickness, burrs, and bulging are all prone to fluctuations in welding current, affecting welding.