Differences Between AS 3679 Steel Grades 300 Series

The Australian Standard AS 3679 covers hot-rolled structural steel plates, strips, and bars used in construction and engineering. Among its grades, 300, 300L0, 300L15, and 300S0 are commonly used but differ in chemical composition, mechanical properties, weldability, machinability, and applications. Below is a detailed comparison.

• Description: General-purpose structural steel with a minimum yield strength of 300 MPa.
• Impact Resistance: No specific low-temperature impact resistance requirements.
• Applications: Suitable for general structural applications where low-temperature impact resistance is not a critical factor.
• Mechanical Properties:

Yield Strength: ≥ 320 MPa (thickness < 11 mm), ≥ 300 MPa (thickness 11 - 17 mm), ≥ 280 MPa (thickness > 17 mm).

Tensile Strength: ≥ 440 MPa.

Elongation: ≥ 22%.

• Description: Structural steel with low-temperature impact resistance tested at 0°C.
• Impact Resistance: Requires a minimum impact energy of 27 Joules at 0°C.
• Applications: Suitable for applications in colder climates where materials may be exposed to temperatures around 0°C.
• Mechanical Properties:

Yield Strength: Similar to Grade 300, but with additional impact resistance requirements.

Tensile Strength: ≥ 440 MPa.

Elongation: ≥ 22%.

• Description: Structural steel with enhanced low-temperature impact resistance tested at -15°C.
• Impact Resistance: Requires a minimum impact energy of 27 Joules at -15°C.
• Applications: Ideal for applications in extremely cold environments where temperatures may drop to -15°C.
• Mechanical Properties:

Yield Strength: Similar to Grade 300, but with additional impact resistance requirements.

Tensile Strength: ≥ 440 MPa.

Elongation: ≥ 25%.

• Description: Structural steel designed for seismic applications, offering enhanced performance in earthquake-prone areas.
• Impact Resistance: Specific requirements to ensure the material performs well under seismic conditions.
• Applications: Suitable for construction in areas with high seismic activity.
• Mechanical Properties:

Yield Strength: Similar to Grade 300, but with additional seismic performance requirements.

Tensile Strength: ≥ 440 MPa.

Elongation: ≥ 25%.

Grade 300: General-purpose steel without specific low-temperature or seismic requirements.

Grade 300L0: Adds low-temperature impact resistance at 0°C.

Grade 300L15: Offers enhanced low-temperature impact resistance at -15°C.

Grade 300S0: Designed for seismic applications, ensuring better performance in earthquake-prone areas.

Each grade is tailored to meet specific environmental and operational conditions, allowing engineers to select the most appropriate material for their projects.