STKM13C Carbon Steel Tubes

STKM13C is a low-carbon steel tube grade defined under JIS G3445, the Japanese Industrial Standard for carbon steel tubes used in machine and structural purposes. It is produced as a cold drawn or hot rolled seamless tube and is widely used for hydraulic cylinders, pneumatic cylinders, and precision machine components where tight dimensional tolerance and a clean inner/outer surface finish are required.

An STKM13C tube is primarily used to manufacture hydraulic and pneumatic cylinder barrels, hydraulic hard pipes for oil circuits, and precision automotive tubing. Its low carbon content allows it to be cold bent and flared without cracking, which makes it suitable for machinery, automobile, bicycle, furniture, and appliance components.

STKM13C material properties include a minimum tensile strength of approximately 510 N/mm² and a minimum yield strength of approximately 380 N/mm² per the JIS G3445 mechanical property table, with a minimum elongation of 15%. In bright-annealed condition, the typical tensile strength reaches around 635 MPa with a yield strength of around 565 MPa, depending on the supplier's processing route. STKM13C also offers good cold formability, allowing bending and flattening without surface cracking.

The STKM13C chemical composition is controlled primarily through carbon, silicon, manganese, phosphorus, sulphur, and chromium content. Per JIS G3445, Grade 13C allows a maximum carbon content of 0.25%, silicon up to 0.35%, manganese between 0.30% and 0.90%, with phosphorus and sulphur each capped at 0.040% maximum. This low-carbon composition is what gives STKM13C its excellent cold workability.

The closest STKM13C equivalent material is JIS D3517 Grade 13C, which is essentially the same grade referenced under a related Japanese standard. STKM13C is broadly comparable to other low-carbon cold drawn precision tube grades used internationally for hydraulic and pneumatic applications, though buyers should always confirm equivalence against the specific chemical and mechanical requirements of the destination standard before substitution.

STKM13A, STKM13B, and STKM13C are all sub-grades within JIS G3445 Grade 13, differentiated by manufacturing method, cold working process, and heat treatment rather than by base chemical composition. STKM13C typically refers to tubes that have undergone additional cold working or specific finishing to meet tighter mechanical property and surface finish requirements compared to STKM13A.

Yes. STKM13C, STKM 13C, and STKM-13C all refer to the same JIS G3445 grade designation. The spacing or hyphenation is a stylistic variation used across technical datasheets, RFQs, and supplier catalogs, and does not indicate a different material specification.

Amardeep Steel Centre supplies STKM13C tubes across a wide range of outside diameters and wall thicknesses to meet JIS G3445 tolerance classes, including the common OD 25.4mm size referenced in standard stock lengths. Custom sizing, cold drawn seamless and hot rolled options are available on request — contact our sales team with your specific OD, ID, and length requirement for a quote.