Performance of High-Quality Carbon Steel No. 20 Seamless Steel Pipe

No. 20 seamless steel pipe is a high-quality steel pipe product made from high-quality carbon structural steel, offering high strength and excellent workability. The pipe is perforated to form a rough tube, followed by hot rolling, cold rolling, or cold drawing to form the finished product. No. 20 seamless steel pipe is classified as low-carbon steel. Carbon steel can be categorized as low-carbon steel, medium-carbon steel, and high-carbon steel based on its carbon content. No. 20 seamless steel pipe has a lower carbon content and is widely used in structural steel pipes, fluid pipes, and low- and medium-pressure boiler pipes. Unless otherwise specified, no. A 20 seamless steel pipe is generally used.

No. 20 seamless steel pipe is made from No. 20 steel and is a high-quality steel pipe product. 20# seamless steel pipe is compliant with standards including GB/T8162-2008, GB/T8163-2008, GB3087-2008, GB6479-2000, and GB9948-2006. It is widely used in the transportation of oil, natural gas, coal, water, and certain solid materials. Compared to 15# steel, 20# seamless steel pipe has slightly higher strength and higher cold deformation plasticity, making it suitable for processes such as bending, rolling, flanging, and hammering. 20# seamless steel pipe also offers excellent weldability, making it suitable for arc welding and contact welding. Gas welding allows for thinner thicknesses, making it suitable for manufacturing parts with strict or complex shapes. 20# seamless steel pipe also offers excellent machinability, making it suitable for manufacturing products that require low stress but high toughness. Its hardness is slightly lower than that of 45# seamless steel pipe.

The chemical composition of 20# seamless steel pipe includes carbon, silicon, manganese, sulfur, phosphorus, chromium, nickel, and copper. Among them, the carbon content is 0.17-0.24, the silicon content is 0.17-0.37, the manganese content is 0.35-0.65, the sulfur and phosphorus contents are not higher than 0.035, and the chromium, nickel, and copper contents are not higher than 0.25. The mechanical properties of 20# seamless steel pipe are also relatively good. Its tensile strength σb (MPa) is not less than 410 (42), the yield strength σs (MPa) is not less than 245 (25), the elongation δ5 (%) is not less than 25, and the cross-sectional shrinkage ψ (%) is not less than 5. The hardness does not exceed 156HB when it is not heat-treated, and the sample size is 25mm. It can be seen that 20# seamless steel pipe is a high-quality steel pipe product with high strength and toughness, which is widely used in various fields.

Heat treatment specifications are the key to ensuring the quality of 20# seamless steel pipe. According to the specifications, the normalizing temperature should be 910℃, and air cooling is required. In addition, the metallographic structure should include ferrite and pearlite. 20# seamless steel pipes can be delivered unheat-treated or heat-treated (annealed, normalized, or high-temperature tempered). However, the contract must specify that heat-treated delivery is required; otherwise, the pipe will be delivered unheat-treated. The formula for calculating the weight of 20# seamless steel pipe is [(outer diameter - wall thickness) * wall thickness] * 0.02466 = kg/meter (weight per meter). The process flow for sanitary mirror-finished steel pipe is largely the same as that for industrial steel pipe, including steel billet inspection, peeling, heating, perforation, pickling, grinding, lubrication and air-drying, welding, cold drawing, solution treatment, pickling and passivation, inspection, cold rolling, degreasing, cutting, air-drying, internal and external polishing, labeling, and finished product packaging. Strict adherence to these specifications and process flow ensures the quality and performance of 20# seamless steel pipes.