Cold drawn (rolled) seamless steel pipe: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) multi-pass cold drawn (cold rolled) billet → heat treatment → straightening → Hydrostatic test (flaw detection) mark → Warehouse.
Hot rolled (extruded seamless steel pipe) round tube blank → heating → piercing → three-roll cross rolling, continuous rolling or extrusion → tube removal → sizing (or diameter reduction) cooling → billet tube → straightening → hydraulic pressure Test (or flaw detection) mark → put into storage.
After pickling to remove the oxide scale, cold rolling is performed. Cold-drawn seamless steel pipes use hot-rolled steel coils as raw materials. The finished product is a hard rolled coil. Due to the cold work hardening caused by continuous cold deformation, the strength and hardness of the hard rolled coil increase, and the toughness and plasticity index decrease. Therefore, the stamping performance will deteriorate and it can only be used for parts with simple deformation. Hard rolled coils can be used as raw materials in hot-dip galvanizing plants because hot-dip galvanizing units are equipped with annealing lines. The weight of hard rolled coils is generally 6~13.5 tons, and the inner diameter of steel coils is 610mm.
Meet the mechanical performance indicators specified in the corresponding specifications. Generally, cold continuous rolled plates and coils should undergo continuous annealing (CAPL unit) or bell furnace annealing to eliminate cold work hardening and rolling stress.
And the product thickness can be reduced to about 0.18mm. The appearance quality, appearance, and dimensional accuracy of cold-rolled steel plates are better than those of hot-rolled plates. Therefore, it is favored by the majority of users. Cold-rolled steel coils are used as substrates for the deep processing of products to become high-value-added products. Such as electro-galvanizing, hot-dip galvanizing, fingerprint-resistant electro-galvanizing, color-coated steel coils, vibration-absorbing composite steel plates, PVC laminated steel plates, etc. These products have excellent qualities such as beauty and high corrosion resistance and are widely used. After annealing, cold-rolled steel coils must be finished, including head, tail, edge trimming, leveling, flattening, recoiling, or longitudinal shearing, etc. Cold-rolled products are widely used in automobile manufacturing, home appliances, instrument switches, construction, office furniture, and other industries. The weight of each bundle of steel plates is 3~5 tons. The flat roll weight is generally 3~10 tons/roll. Steel coil inner diameter 610mm
Heated by a walking heating furnace, hot-rolled seamless steel pipes use continuous casting slabs or blooming slabs as raw materials. After being descaled by high-pressure water, it enters the rough rolling mill. The rough rolled material is cut at the beginning and end and then enters the finishing mill for computer-controlled rolling. After the final rolling, it undergoes laminar cooling and coiling to become straight coils. The head and tail of straight hair curlers are often tongue-shaped and fish-tail-shaped, with poor thickness and width accuracy, and the edges often have defects such as wavy shapes, folded edges, and tower shapes. Its coil weight is relatively heavy and the inner diameter of the steel coil is 760mm. It is generally used in the pipe-making industry. After the straight coils are processed by head cutting, tail cutting, edge trimming and multi-pass straightening, leveling, and other finishing lines, they are then cut into plates or re-rolled to become: hot-rolled steel plates, flat hot-rolled steel coils, longitudinal steel coils, etc. Cutting tape and other products. If the hot-rolled finished rolls are pickled to remove scale and oiled, they become hot-rolled pickled rolls. This product tends to partially replace cold-rolled plates, is moderately priced, and is very popular among users.
Post time: Jan-17-2024