What is the content of high quality carbon structure tube?

Such steel must have both chemical composition and mechanical properties. The contents of sulfur (S) and phosphorus (P) are generally controlled below 0.035%. If it is controlled below 0.030%, it is called high quality steel, and "A" should be added after the grade, such as 20A; If P is controlled below 0.025% and S is controlled below 0.020%, it is called extra high quality steel, and "E" should be added after the grade to show the difference. For other residual alloying elements brought into steel by raw materials, such as chromium (Cr), nickel (Ni), copper (Cu), etc., the content of Cr≤0.25%, Ni≤0.30%, Cu≤0.25%. Some brands of manganese (Mn) content up to 1.40%, known as manganese steel.

This kind of steel depends on the adjustment of carbon content (C) to improve the mechanical properties of steel, therefore, according to the level of carbon content, this kind of steel can be divided into:

Low carbon steel - carbon content is generally less than 0.25%, such as 10, 20 steel, etc.

Medium carbon steel - carbon content is generally between 0.25 ~ 0.60%, such as 35, 45 steel, etc.

High carbon steel - carbon content generally greater than 0.60%. Such steel is not normally used to make steel pipes.

In fact, there is no clear limit to the carbon content between them.

This kind of steel output is larger, more widely used, generally rolled (forging) into round, square, flat and other profiles, plates and seamless steel pipe. It is mainly used for manufacturing general structure and mechanical structure parts and components as well as building structural parts and pipelines for conveying fluids. According to the requirements of use, sometimes need heat treatment (normalizing or tempering) after use.