JIS G3445 STKM11A

JIS G3445 STKM11A is a standard material for carbon seamless steel pipes for mechanical parts in Japan.

High-quality carbon structural steel is carbon steel with carbon content less than 0.8%. The steel contains less sulfur, phosphorus and non-metallic inclusions than carbon structural steel, and has excellent mechanical properties.

JIS G3445 STKM11A steel contains a certain amount of silicon (Si) (generally not more than 0.40%) and manganese (Mn) (generally not more than 0.80%, up to 1.20%) in addition to carbon (C) element and deoxidation. Except for alloying elements, it does not contain other alloying elements (except for residual elements). This type of steel must ensure both chemical composition and mechanical properties. The content of sulfur (S) and phosphorus (P) impurity elements is generally controlled to be less than 0.035%. If the control is below 0.030%, it is called high-quality steel, and the grade should be followed by “A”, for example, 20A; if P is controlled below 0.025% and S is controlled below 0.020%, it is called premium grade steel, and its grade should be added after the grade. "E" to show the difference. The content of other residual alloying elements such as chromium (Cr), nickel (Ni), copper (Cu) and the like which are brought into the steel by the raw material is generally controlled to be Cr ≤ 0.25%, Ni ≤ 0.30%, and Cu ≤ 0.25%. Some grades of manganese (Mn) content of 1.40%, called manganese steel.

Such steel has a large output and is widely used. Generally, it is rolled (forged) into round, square and flat profiles, plates and seamless steel pipes. Mainly used in the manufacture of general structural and mechanical structure zeros, components and building structural parts and pipelines for conveying fluids. According to the application requirements, it is sometimes necessary to use heat treatment (normalizing or quenching).