The quality of galvanized square pipes is high. However, due to the inevitable quality defects in the production of steel pipe production, and some steel pipes are served under some special environmental conditions, except for the comprehensive performance, outer diameter and wall thickness accuracy of steel pipes, and flatness accuracy, and flatness accuracy, and flatness accuracy, and flatness accuracy, and flatness accuracy and flatness. In addition to the requirements of the straightness, special requirements are also made for its surface, end surface, and anticorrosive.
In order to meet the above requirements, the steel pipes need to be directly straight and defective after cooling; the necessary processing of the pipe end; check the steel pipe performance inspection (test), check the qualified steel pipes, and then perform long, weighing, identifiable identification , Packaging Ren Library. In short, the refined process of steel pipes is to remove the defects of steel pipes, further improve the quality of steel pipes, meet the needs of product special purpose, and clarify that the "identity" of the product "identity" is an indispensable and important process. The steel pipeline is mainly included: the steel pipe is straight, the end of the cut (inverted edge, the ruler)
Inspection and inspection (including surface quality inspection, geometric size inspection, non -destructive inspection, and hydraulic test), grinding, long, weight, weighing, paint, jet and packaging and other processes. Some special -purpose steel pipes also need to be sprayed, mechanical processing, anticorrosive treatment, etc.
In various processes with refined steel pipes, the requirements of the steel pipe inspection and inspection process are introduced in the first chapter. In addition to the length, weighing, paint, printing, and packaging of steel pipes, except that it may cause mild defects such as bumps and scratches of steel pipes, the shape, size and performance of the steel pipe will not change. Therefore, this chapter aims to focus on the quality defects and preventive measures produced in three processes involving steel pipe deformation or processing in three processes involving steel pipe deformation or processing.
Introduction to the quality requirements of galvanized square tube surface
The standard specifies the "surface smooth" requirements of the steel pipe. However, there are as many as 10 steel pipe surface defects caused by various reasons. These defects mainly include: surface cracks (cracks), hair pattern, inner folding, outer folding, rolling, inner straight roads, outer straight, scars, concave pits, bumps, anesthesia (hemp surface), hemps (hemp surface), inner trails, outer trails, outer trails, outer trails, exterior trails, scars, concave pits, convex pits, hemp surface (hemp surface), and hemp (hemp surface), hemp (hemp surface), and hemp (hemp surface), hemp (hemp surface), and hemp (hemp surface), hemp (hemp surface), and hemp (hemp surface), hemp (hemp surface), and hemp (hemp surface), hemp (hemp surface), and hemp (linen), hemp (hemp surface), and hemp (hemp surface), hemp (hemp surface), and hemp (hemp surface). Tear (scratching), internal spiral roads, external spiral roads, blue lines, orthopedic concave, roller prints, etc. In the above -mentioned steel pipe surface defects, some defects are very serious to the performance of steel pipe performance, which is called risk defects, such as steel pipe cracks (cracks), inner folding, outer folding, rolling, departure, condensation, pulling, pulling, pulling Caval, convex bag, etc.; Some defects have a relatively small impact on the performance of the steel pipe, which are called general defects, such as steel pipe anesthesia (surface), blue line, rubbing (scratch, touch) injury, slight inner trail and outer straight road. , Slight internal spiral roads and external spiral roads, orthopedics, roller prints, etc.
The process requirements are that the first layer of welding must be welded to ensure good back forming, welding current, arc voltage, wire delivery speed and welding speed. The welding deformation produced from the middle to the two sides is smaller than the direct welding, which is conducive to the decentralization and release of stress, and avoid complex stress in welding. The narrow plastic deformation zone formed by the welding of the welding of the direct swing is only once, and due to the continuous swing welding, the heat input volume is large, the heating area is large, and the plastic deformation area caused by compression is large, so the shrinkage and deformation after welding are large.
When the segmented jump welding, each layer of the section is small, the required heat is small, and each layer is divided into several sections to jump welding. Each section is basically re -established on the cold steel plate. Every time, a narrow plastic deformation area appears, so the average width of the plastic deformation zone is smaller than the corresponding layered straight through welding, and the vertical contraction is also smaller. Compared with the swing welding deformation that is filled once in a row, it is smaller.
