Cold rolling refers to processing steel plates or steel strips into various steel products through cold processing such as cold drawing, cold bending, and normal temperature cold drawing.
Carbon steel pipes are divided into two categories: hot-rolled steel pipes and cold-rolled (drawn) steel pipes. Carbon steel pipes are made from steel ingots or solid billets by perforating them into capillary tubes, and then hot rolling, cold rolling or cold drawing. Carbon steel pipes occupy an important position in my country's steel pipe industry.
Cold-rolled carbon steel pipes are cold-drawn or cold-rolled precision seamless steel pipes with high dimensional accuracy and good surface finish used in mechanical structures and hydraulic equipment. In addition to ordinary 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 (drawn) seamless pipes also include carbon thin-walled steel pipes. - Thin-walled steel pipes, alloy thin-walled steel pipes, stainless steel thin-walled steel pipes, special-shaped steel pipes. The outer diameter of hot-rolled seamless pipes is generally greater than 32mm, and the wall thickness is 2.5-75mm. The diameter of 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.
Ordinary carbon steel pipes: hot-rolled or cold-rolled from high-quality carbon steels such as 10, 20, 30, 35, 45, 16Mn, 5MnV and other low-alloy structural steels, or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steels. Seamless pipes made of low carbon steel such as No. 10 and No. 20 are mainly used for fluid transportation pipelines. Medium carbon steel seamless pipes such as 45 and 40Cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Carbon steel pipes are generally used to ensure strength and flattening tests. Hot-rolled steel pipes are delivered in a hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in a 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 component after buckling can be fully utilized; while hot-rolled section steel does not allow local buckling of the section.
2. The causes of residual stress in hot-rolled steel plates and cold-rolled steel plates are different, so the distribution on the cross-section is also very different. The residual stress distribution on the cold-formed thin-walled steel section is curved, while the residual stress distribution on the hot-rolled or welded steel section is film-like.
3. The free torsional stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsional performance of hot-rolled steel is better than that of cold-rolled steel.
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