Which chemical elements affect the quality of steel pipes

At present, my country is actively developing the steel structure industry. At first, it actively expanded the varieties of large-diameter spiral steel pipes used in the construction of steel structures to improve product performance. Including high-quality welded structural steel, high-strength high-quality thick plate, thermoformed pipe, high-quality weldable cast steel, etc.; expand the varieties and specifications of cold-formed steel, and hot-rolled H-beam, including large-section cold-formed pipe, large-section H-beam, and Light H-shaped steel, etc.; reasonably promote the use of weathering steel, refractory steel, Z-direction steel, and flux-cored electrodes, etc. Secondly, vigorously promote the development of building steel structures, and further improve the level of its application technology. my country's steel structure industry is developing rapidly. Steel structure buildings are a new type of energy-saving and environmentally friendly building system. Steel structure buildings are light in weight, high in strength, good in seismic performance, energy-saving and environmentally friendly, and can be recycled. The requirements for the sustainable and healthy development of construction and economy. Steel pipes also include special systems for transporting liquefied petroleum gas and liquefied gas. The service life of steel pipes in offshore engineering is at least 40 years. In addition to conventional systems in offshore engineering, there are also special drilling equipment systems, crude oil, liquefied petroleum gas, and liquefied natural gas processing process systems.

Steel pipes can be divided into round pipes and special-shaped pipes according to the shape of the cross-sectional area. Since the circular area is larger under the condition of equal circumference, more fluid can be transported with circular tubes. In addition, when the ring section is subjected to internal or external radial pressure, the force is relatively uniform, so most steel pipes are round pipes.

Which chemical elements affect the quality of steel pipes?
(1) Nickel (Ni): Nickel can increase the strength of steel, and can also maintain good plasticity and toughness of steel. Effects of several main elements in steel on properties of steel.
(2) Chromium (Cr): Chromium can significantly improve the strength, hardness, and wear resistance of steel, but at the same time reduce plasticity and toughness.
(3) Titanium (Ti): Titanium is a deoxidizer in steel. Reduced effect sensitivity and cold brittleness. Adding a corresponding amount of titanium to steel can resist intergranular corrosion.
(4) Molybdenum (Mo): Adding molybdenum to steel can improve the mechanical properties of steel.
(5) Carbon (c): As the carbon content increases, the yield point and tensile strength increase, but the plasticity and impact properties decrease. If the carbon content is too high, it is easy to cause unqualified intergranular corrosion. The boundary between steel and iron is controlled by the C content.
(6) Sulfur (S): Sulfur is a harmful element in steel, which causes hot brittleness of steel, reduces the ductility and toughness of steel, easily causes cracks during forging, and also reduces the corrosion resistance of steel. Therefore, the sulfur content must be controlled as low as possible.
(7) Silicon (Si): Si is a deoxidizer and desulfurized with high strength and hardness, which can improve the hot workability of steel.
(8) Phosphorus (P): Phosphorus is a harmful element in steel, which increases the cold brittleness of steel, deteriorates welding performance, reduces plasticity, and deteriorates cold bending performance. Usually, the lower the phosphorus content in steel is controlled, the better.
(9) Nitrogen (N): Nitrogen can improve the strength, low-temperature toughness, and weldability of steel. Increased effectiveness sensitivity. An appropriate amount of nitrogen can improve the pitting corrosion resistance and strength of stainless steel.