Cold rolling refers to the processing of steel plates or strips into various types of steel through cold working such as cold drawing, cold bending, and cold drawing at room temperature.
Carbon steel pipes are divided into two categories: hot-rolled and cold-rolled (drawn) steel pipes. Carbon steel pipes are made of steel ingots or solid billets through perforation into capillary tubes, which are then hot-rolled, cold-rolled or cold-drawn. Carbon steel pipe plays an important role in my country’s steel pipe industry.
Cold rolled carbon steel pipe is a cold-drawn or cold-rolled precision seamless steel pipe for mechanical structure and hydraulic equipment with high dimensional accuracy and good surface finish. In addition to general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, cold-rolled (pulled) seamless pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, Stainless thin-walled steel pipe, special-shaped steel pipe. The outer diameter of the hot-rolled seamless pipe is generally greater than 32mm, and the wall thickness is 2.5-75mm. The diameter of the cold-rolled seamless pipe can reach 6mm and the wall thickness can reach 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
Hot rolled steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.
General carbon steel pipe: It is made of 10, 20, 30, 35, 45 and other high-quality carbon steel 16Mn, 5MnV and other low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot-rolled or cold-rolled. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. 45, 40Cr and other medium carbon steel seamless pipes are used to manufacture mechanical parts, such as the stressed parts of automobiles and tractors. Generally, carbon steel pipes are used to ensure the strength and flattening test. Hot-rolled steel pipes are delivered in hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in heat-treated state.
The difference between cold rolling and hot rolling:
1. Cold-rolled section steel allows local buckling of the section, so that the bearing capacity of the member after buckling can be fully utilized; while hot-rolled section steel does not allow local buckling of the section.
2. The reasons for the residual stress of hot-rolled steel and cold-rolled steel are different, so the distribution on the cross-section is also very different. The residual stress distribution on the section of cold-formed thin-walled steel is curved, while the residual stress distribution on the cross-section of hot-rolled or welded steel is thin-film.
3. The free torsional stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsion resistance of hot-rolled steel is better than that of cold-rolled steel.
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