STKM11A Seamless Steel Tube 30-325mm OD 2-100mm Thick for Auto Parts
Détails de produit
seamless steel tube for auto parts
,precision steel tube 30-325mm OD
,steel tube 2-100mm thick
STKM11A Heavy Thick-Wall Precision Seamless Steel Tubing — Technical Product Description
Material Overview
STKM11A is a carbon (mild) steel grade under the JIS G 3445 standard, specified for seamless steel tubes used in machine structural applications. It is used for heavy thick-wall tubing in automotive parts and other mechanical components where strength, formability, and consistency are required.
Specifications
| Parameter | Detail |
|---|---|
| Standard | JIS G 3445: Carbon steel tubes for machine structural purposes. |
| Form | Seamless steel tubing (also hot-rolled or cold drawn depending on required precision) |
| Dimensions (Typical) | Outer Diameter (OD): ~6 mm to ~340 mm; Wall Thickness (WT): ~1 mm to ~50 mm. |
| Delivery Conditions | Bright annealed or otherwise heat treated per JIS G3445; tolerances on OD and wall thickness per the standard. |
Chemical Composition: Comparison Among Similar STKM Grades
Here is a table showing STKM11A and 4 other related STKM grades (used in similar applications) with their chemical composition limits under JIS G 3445.
| Grade | C (max) | Si (max) | Mn (max or range) | P (max) | S (max) |
|---|---|---|---|---|---|
| STKM11A | 0.12 % | 0.35 % | 0.60 % | 0.040 % | 0.040 % |
| STKM12A | 0.20 % | 0.35 % | 0.60 % | 0.040 % | 0.040 % |
| STKM13A | 0.25 % | 0.35 % | 0.30–0.90 % | 0.040 % | 0.040 % |
| STKM13C | ~0.25 % | 0.35 % | 0.30–0.90 % | 0.040 % | 0.040 % |
| STKM14A | 0.30 % | 0.35 % | 0.30–1.00 % | 0.040 % | 0.040 % |
Mechanical Properties
Below is a table showing mechanical property minima for STKM11A and four other related grades from JIS G 3445, useful for heavy thick-wall applications such as automotive components.
| Grade | Tensile Strength (min) MPa | Yield/Proof Stress (min) MPa | Elongation (min) % | Notes on Formability / Bend / Flattening |
|---|---|---|---|---|
| STKM11A | 290 MPa | — (some sources specify proof stress ~ not always declared) | 35 % | Must pass flattening test (half diameter), specific bend tests, straightness etc. |
| STKM12A | 340 MPa | 175 MPa | 35 % | Bend tests: 90° etc. |
| STKM13A | 370 MPa | 215 MPa | 30 % | More demanding flattening, bend radius, etc. |
| STKM13C | 510 MPa | 380 MPa | 15 % | Lower elongation but higher strength; suited where higher load, less deformation acceptable. |
| STKM14A | 410 MPa | 245 MPa | 25 % | Intermediate grade between STKM13 and STKM15 in strength vs ductility. |
Key Features
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Low Carbon Content → good formability, weldability, machinability. STKM11A’s carbon ≤ 0.12 % makes it relatively mild steel.
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Good Ductility and Elongation → high elongation (≥ 35 %) allows forming, bending, and deformation without cracking, which is useful in automotive parts where bending or shaping is needed.
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Adequate Strength for general machine structural parts: tensile ≥ ~290 MPa. Enough for many auto part uses where ultra high strength isn’t necessary.
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Uniformity and Precision: being seamless (no welds), tight tolerances on OD and wall thickness, straightness, surface finish. Useful when assembly, sliding fit, or sealing involved.
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Cost-Effective compared to higher alloys or heat-treated steels. Mild steel grades like STKM11A tend to be less expensive and easier to produce.
Standard / Execution Requirements
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Standard: JIS G 3445 — Carbon steel tubes for machine structural purposes.
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Dimensional Tolerances: Outside diameter and wall thickness tolerances per divisions defined in JIS G 3445. For example, for OD under 50 mm, tolerance ±0.5 mm; for larger sizes, percentage-based.
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Mechanical Property Testing: Tensile, elongation, flattening test (e.g., flatten without crack), bending test requirements (degree, radius) stipulated.
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Appearance: Tubes must be practically straight; ends square to axis; surface free from defects detrimental to use.
Application Fields
General Application Domains
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Automotive parts
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Machinery components
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Mechanical structures
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Hydraulic or pneumatic systems
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Furniture, appliances
Specific Uses within Automotive / Auto Parts
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Drive shafts and steering shafts (where strength + precise fit matters)
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Tubing for shock absorbers or suspension components (where wall thickness must withstand loads)
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Auto chassis sub-components requiring seamless tubing for durability under vibration
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Bushings, bearing housings, sleeve tubes where precise inner diameter and straightness are needed
Q: Are you trading company or manufacturer ?
A: manufacturer,also can do trading.
Q: How long is your delivery time?
A: Generally speaking,it is 10-15 days if the goods are in stock,or it is 30-40 days if the goods are not in stock,
it is according to quantity.
Q: Do you provide samples? is it free or extra ?
A: Yes, we could offer the sample for free charge but need pay the cost of freight.
Q: What is your terms of payment ?
A: Payment<=2000USD, 100% in advance. Payment>=2000USD, 30% T/T in advance ,balance before shippment.
If you have another question, pls feel free to contact with me.
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