STKM17C  JIS G3445 Carbon Steel Seamless Tube for Automobiles / Mechanical Structure

What is this product

The grade STKM17C refers to a type of carbon steel seamless (or welded) tube specified under JIS G3445 ("Carbon steel tubes for machine structural purposes"). 
It is commonly used for machine structure and automotive applications — for example as components in automotive frames, shafts, suspension parts, etc. 

Specifications

• Standard: JIS G3445 (latest version, e.g. 2021) 

• Steel grade: STKM17C (sometimes referred as “Grade 7, C‑type / cold‑finished carbon steel tube”) 

• Manufacturing methods: Hot‑rolled seamless, cold‑drawn seamless, or welded tube, depending on requirement. 

• Common tube size ranges: Outer diameter and wall‑thickness vary depending on supplier/specification; typical diameter range for JIS G3445 tubes spans from small precision tube to larger structural tube (depending on use) — in practical supply OD from ~6 mm up to much larger diameters. 

Key Features

• Balanced carbon content giving relatively high strength compared to low‑carbon structural tubes, while retaining reasonable formability and weldability. 

• Because of high carbon (and manganese) content, STKM17C tubes provide improved hardness and “shape‑holding” ability — useful where the tube must resist deformation under load or stress (e.g. shafts, structural components, etc.) 

• Controlled impurities (low phosphorus and sulfur) improve toughness and reduce defects during processing (like welding, bending, cold forming). 

• Good applicability to processes common in automotive manufacturing and mechanical engineering: welding, machining, cold forming, bending, etc. 

Chemical Composition

Mechanical Properties

Applicable Standards

• Main standard: JIS G3445 — “Carbon steel tubes for machine structural purposes.” 

• Manufacturing and delivery conditions, chemical composition, mechanical tests, and marking requirements follow the clauses of JIS G3445 (and related referenced JIS test standards, e.g. for tensile test, flattening test, bending test). 

Application Fields & Typical Uses

Application Fields

• Automotive components (chassis parts, suspension components, shafts, structural supports) — where high strength and reliability are required.

• Mechanical structures and machinery: frames, machine parts, supports, shafts, tubular components subject to stress or load.

• Bicycle, furniture, appliance structural frames (though for lower-demand applications, lower‑carbon STKM may be preferred).

Typical Uses in Automotive & Mechanical Context

• Drive shafts, suspension struts or supports, structural tubes in frames or subframes — because STKM17C’s strength and hardness help resist bending, torsion, and fatigue.

• Machine structural tubular components — hydraulic cylinders, load-bearing tubes, supports, frames.

• Any steel tube application requiring a balance of strength, weldability, and formability, where prefabrication or precise machining is needed.

Why STKM17C Is Often Selected — Our Advantages

• High strength and load-bearing capacity: With a minimum tensile strength of 650 MPa and yield of 480 MPa, STKM17C tubes offer strong mechanical performance — ideal for automotive structural parts and heavy‑duty mechanical components.

• Balanced ductility and toughness: Despite higher carbon content, controlled manganese and low impurities (P & S) retain acceptable elongation and toughness, allowing welding, machining, and forming without excessive brittleness.

• Compliance with a recognized standard (JIS G3445): Ensures consistency, quality control (chemical composition, mechanical testing, dimensional tolerances), making procurement and quality assurance more manageable and reliable for clients.

• Versatility in manufacturing processes: Available as seamless hot‑rolled, cold‑drawn, or welded tubes, giving flexibility depending on required dimension tolerance, surface finish, and structural requirements.

• Cost-effectiveness for structural applications: Compared to alloy steels or specialized high-alloy tubing, STKM17C offers a good balance of cost vs performance for many automotive and machine‑structural uses.

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.

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