Do You Know What Is a Structural Steel Pipe?

Structure steel pipe is a type of seamless steel pipe divided according to its different uses.

Overview:

GB / T8162-2018 seamless steel pipe for structure is mainly used for general structure and machining. Its representative materials (brands): carbon steel 20 #, 45 steel; alloy steel Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc.

Structural stainless steel seamless pipe (GB / T14975-2002) is a hot-rolled (extruded, extruded, Expansion) and cold drawn (rolled) seamless pipe.

Structure steel pipe factory china introduces two kinds of structure pipe process:

Cold drawn structural pipes use hot rolled steel coils as raw materials. After pickling to remove scale, cold continuous rolling is performed. The finished product is rolled hard coils. The cold work hardening caused by continuous cold deformation increases the strength, hardness and toughness of rolled hard coils The plastic index decreases, so the stamping performance will deteriorate, and it can only be used for parts that are simply deformed. Hard-rolled coils can be used as raw materials for hot-dip galvanizing plants because hot-dip galvanizing units are equipped with annealing lines. The weight of rolled hard coil is generally 6 ~ 13.5 tons, and the inner diameter of steel coil is 610mm.

Generally, continuous cold-rolled steel sheets and coils should be subjected to continuous annealing (CAPL unit) or bell furnace annealing to eliminate cold work hardening and rolling stress to achieve the mechanical performance indicators specified by the corresponding standards.

The surface quality, appearance, and dimensional accuracy of cold-rolled structural pipes are better than those of hot-rolled structural pipes, and the thickness of products is right-rolled to about 0.18mm, so they are favored by customers. The cold-rolled steel coils are used as the base structural pipe to further process the products, and become high-value-added products. Such as electro-galvanizing, hot-dip galvanizing, fingerprint-resistant electro-galvanizing, color-coated steel sheet rolls, vibration-damping composite steel sheets, PVC coated steel sheets, etc., which make these products have good quality, high corrosion resistance and other excellent qualities, and have been widely used. Cold rolled steel coils must be finished after annealing, including cutting, tailing, trimming, leveling, flattening, rewinding, or longitudinal shearing. Cold rolled products are widely used in automobile manufacturing, home appliance products, instrument switches, construction, office furniture and other industries. The weight of each package after the steel plates are packed is 3-5 tons. The weight of the flat coil is generally 3 ~ 10 tons / roll. The inner diameter of the steel coil is 610mm.

Structure Steel Pipe

Hot-rolled structural tubes use continuous casting slabs or preliminary rolled slabs as raw materials, are heated by a step-type heating furnace, are descaled by high-pressure water, and enter the roughing mill. The rough rolling material is cut into the head, tail, and then enters the finishing mill. After rolling, it will be coiled by laminar flow cooling and coiling machine after final rolling to become straight coil. Straight hair curls tend to be tongue-shaped and fish-tail-shaped, with poor thickness and width accuracy, and often have wavy, folded, and tower-shaped defects on the sides. Its coil weight is heavy and the inner diameter of the steel coil is 760mm. (Generally used in the pipe-making industry.) After straightening the straight hair through cutting, tailing, trimming and multiple straightening and leveling lines, and then cutting or rewinding, it becomes: Steel plate, flat hot rolled steel coil, slitting tape and other products. If the hot-rolled finishing coil is pickled to remove scale and oil, it will become a hot-rolled pickled coil. This product has the tendency to partially replace the cold-rolled structural pipe, the price is moderate, and it is loved by customers.

Chemical heat treatment:

--- Chemical heat treatment is to make the surface of Guizhou structural steel pipe infiltrate the atom of one or several chemical elements, thereby changing the chemical composition, structure and properties of the surface of Guizhou structural steel pipe. After quenching and tempering at low temperature, the surface of Guizhou structural steel pipe has high hardness, wear resistance and contact fatigue strength, and the core of Guizhou structural steel pipe has high strength and toughness.

--- The main technical parameters of Guizhou structural steel pipe for chemical heat treatment are the depth of the hardened layer and the surface hardness. The depth of the hardened layer is still measured by a Vickers hardness tester. Check the distance from the surface of Guizhou structural steel pipe to the point where the hardness drops to 50HRC. This is the surface hardness test of Guizhou structural steel pipe for effective hardening deep chemical heat treatment. The hardness test of Guizhou structural steel pipe for surface hardening heat treatment is similar. Both can be detected by Vickers hardness tester, Rockwell hardness tester or Rockwell hardness tester, but nitriding. Thickness is relatively thin, generally not more than 0.7mm, at this time, Rockwell hardness tester can no longer be used, and microhardness tester can be used.