Common Grades Of JIS G3444 Standard

Tianjin Lefin Industrial Co., Ltd is one of the most experienced manufacturers and suppliers of common grades of jis g3444 standard in China. Please feel free to buy high quality common grades of jis g3444 standard from our factory. Good service and reasonable price are available.

JIS G3444 is a Japanese Industrial Standard that specifies carbon steel tubes for general structural purposes. These tubes are widely used in construction, bridges, machinery, and other structural applications. Among the various grades defined in this standard, the most commonly used grades are STK400 and STK500.

STK400 is one of the most frequently used grades in JIS G 3444 due to its balanced mechanical properties, ease of fabrication, and suitability for general structural applications.

STK400 is a low-carbon steel with the following typical chemical composition:

Carbon (C): Max 0.25%

Silicon (Si): No specific limit

Manganese (Mn): No specific limit

Phosphorus (P): Max 0.040%

Sulfur (S): Max 0.040%

The low carbon content ensures good weldability and formability, making it easy to work with in various fabrication processes.

Minimum Tensile Strength: 400 MPa

Minimum Yield Strength: 235 MPa

Elongation: Varies depending on the manufacturing process and test piece used. For example, seamless and butt-welded tubes have a minimum elongation of 23%, while electric resistance welded and automatic arc-welded tubes have a minimum elongation of 18%.

• These properties make STK400 suitable for applications requiring moderate strength and good ductility.

Building Structures: Used in frames, supports, and trusses for residential and commercial buildings.

Bridge Construction: Employed in secondary structures, guardrails, and pedestrian bridges.

Machinery and Equipment: Utilized in the fabrication of frames, brackets, and supports for machinery.

Scaffolding and Temporary Structures: Commonly used in construction sites for scaffolding and temporary support systems.

• Excellent weldability and formability.
• Cost-effective, making it suitable for large-scale projects.
• Adequate strength for general structural purposes.

STK500 is another widely used grade in JIS G 3444, offering higher strength than STK400. It is typically used in applications requiring greater load-bearing capacity.

STK500 has a similar chemical composition to STK400 but with slightly higher manganese content to enhance strength:

Carbon (C): Max 0.24%

Silicon (Si): Max 0.35%

Manganese (Mn): 0.30% to 1.30%

Phosphorus (P): Max 0.040%

Sulfur (S): Max 0.040%

Minimum Tensile Strength: 500 MPa

Minimum Yield Strength: 355 MPa

Elongation: Varies depending on the manufacturing process and test piece used. For example, seamless and butt-welded tubes have a minimum elongation of 15%, while electric resistance welded and automatic arc-welded tubes have a minimum elongation of 10%.

• The higher tensile and yield strengths make STK500 suitable for heavier load-bearing applications.

Heavy Building Structures: Used in high-rise buildings, industrial facilities, and other structures requiring high strength.

Bridge Construction: Employed in main girders, load-bearing components, and critical structural elements.

Machinery and Equipment: Utilized in heavy-duty machinery frames and components that require high strength and durability.

• Higher strength compared to STK400, making it ideal for heavy-load applications.
• Good weldability and formability despite its higher strength.
• Cost-effective for high-strength structural requirements.

• STK400 is the most commonly used grade in JIS G 3444, offering a balance of strength, weldability, and cost-effectiveness for general structural applications.
• STK500 is preferred for applications requiring higher strength, such as heavy construction and machinery.

Both grades are widely used in construction, infrastructure, and industrial applications due to their excellent mechanical properties, ease of fabrication, and versatility.