The Key Technical of Precision weled steel tube

A, about the quality of the raw material requirements:

Precision welded steel pipe of raw materials, in addition to the must meet the basic requirement of ordinary high-frequency welded steel pipe materials, still must meet the following requirements:

Chemical composition:

Smelting, the key is to improve the purity of steel, reduce the amount of non-metallic inclusions in steel, sulfur and phosphorus content is less than 0.03%, in order to adapt to cold hind leg deformation processing, sulfur content had better not more than 0.02%, so we will strictly control the steel chemical composition. At the same time in order to ensure the product has good mechanical properties, cold bending, welding, such as process performance, still need to appropriately increase some elements, such as Nb, Ni, V.

2 steel strip shape and size:

Steel strip rolling, the AGC should be adopted and flatness control system, improve the steel strip thickness accuracy and shape accuracy. Also, using the method of controlled cooling, improve the tenacity of steel belt. Slitting steel strip width dimension accuracy requirement for control, steel strip edges shall be without creasing and burr, in order to improve the welding quality.

3 rust on the surface of the structural steel pipe:

Steel strip for iron oxide yellow rust on the surface of the water of crystallization, in the process of welding, high temperature can make the hydrogen oxygen out, such as can't discharge, exists in the weld, easy to produce porosity micro cracks, change the organization structure, reduce the material plastic, reduce elongation, so avoid steel strip surface rust.