Steel plays a crucial role in the world of construction, manufacturing, and engineering. Among the numerous types of steel used globally, SS400 steel plates stand out for their reliability, affordability, and versatility. Whether you’re new to this material or just looking to deepen your understanding, this comprehensive guide will help you grasp everything about SS400 steel plates—from its chemical makeup to mechanical strength and typical applications.
What is SS400 Steel?
SS400 is a structural grade steel standard defined under the Japanese Industrial Standard (JIS). The “SS” in SS400 stands for “Structural Steel,” and the “400” refers to the minimum tensile strength of the material, which is 400 MPa. This carbon steel grade is widely used in construction, manufacturing, and general engineering projects due to its excellent weldability and machinability.
In simple terms, SS400 is a low carbon, general-purpose steel that is both cost-effective and easy to work with. It’s a popular material choice across Asia and increasingly used in global industries thanks to its consistent quality and mechanical performance.
Why SS400 is Popular in the Industry
Before we go deeper into the technical aspects, it’s important to understand why SS400 Steel Plates are so widely used.
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Versatility: Suitable for structural applications, automotive parts, machinery, and fabrication.
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Cost-effectiveness: Affordable compared to many other structural steels.
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Good weldability: Can be easily welded without pre-heating or special treatment.
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Readily available: Globally accessible in various forms like plates, sheets, and bars.
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Reliable mechanical properties: Strong enough for moderate-load applications.
SS400 Material Properties
The Material Properties of SS400 make it ideal for a wide range of structural and general engineering applications. Let’s look at the key physical and mechanical characteristics that define SS400 steel plates:
1. Density
The density of SS400 is approximately 7.85 g/cm³, which is standard for carbon steel.
2. Melting Point
SS400 typically has a melting point around 1430–1460°C, making it suitable for high-temperature applications where heat resistance is needed but not extreme.
3. Tensile Strength
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Minimum: 400 MPa
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Maximum: 510 MPa
Tensile strength refers to the maximum stress that the material can withstand while being stretched before breaking. SS400’s tensile strength places it within the lower-middle range among structural steels, suitable for standard construction purposes.
4. Yield Strength
The SS400 Yield Strength usually ranges between 245 MPa and 275 MPa depending on the thickness of the steel plate.
Yield strength is a critical property that indicates the stress at which a material begins to deform permanently. For SS400, this means it can support moderate loads without compromising structural integrity.
5. Elongation
SS400 typically has an elongation percentage of 20–25% in 200 mm, depending on the thickness. This measure indicates how much the steel can stretch before it fractures—a key feature for applications requiring some flexibility under stress.
SS400 Chemical Composition
Understanding the SS400 Chemical Composition is essential for assessing its weldability, machinability, and corrosion resistance.
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.050 |
| Manganese (Mn) | ≤ 1.60 |
| Phosphorus (P) | ≤ 0.050 |
| Sulfur (S) | ≤ 0.050 |
| Iron (Fe) | Balance |
Key Notes:
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Low Carbon Content: This makes SS400 easier to weld and machine.
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Balanced Manganese: Helps improve strength and hardness without reducing ductility.
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Controlled Impurities: Phosphorus and sulfur are kept low to avoid brittleness.
SS400 Yield Strength
This basic yet effective composition allows SS400 Steel Plates to perform well in standard structural applications, offering a good balance between strength, ductility, and processability.
One of the most important mechanical properties of steel is Yield Strength, and for SS400 Steel Plates, this property determines their suitability in structural and load-bearing applications.
SS400 Yield Strength Range
The Yield Strength of SS400 depends largely on the thickness of the steel plate:
| Thickness Range | Minimum Yield Strength (MPa) |
|---|---|
| ≤ 16 mm | 245 MPa |
| > 16 mm and ≤ 40 mm | 235 MPa |
| > 40 mm and ≤ 100 mm | 225 MPa |
| > 100 mm | 215 MPa |
Common Applications of SS400 Steel Plates
Due to its mechanical properties and affordable cost, SS400 steel plates are used in a wide range of industries and applications:
1. Construction & Infrastructure
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Beams, channels, and structural components
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Bridges, high-rise buildings, and industrial sheds
2. Machinery and Equipment
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Frame structures
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Equipment housings
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Machinery bases
3. Automotive Industry
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Chassis components
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Vehicle body parts (non-critical)
4. Shipbuilding and Marine Structures
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Deck plating
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Hull structures in low-stress areas
5. General Fabrication
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Storage tanks
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Fencing and gates
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Furniture and brackets
Final Thoughts
SS400 Steel Plates offer a solid balance of performance, affordability, and ease of use. Whether you’re working in construction, manufacturing, or machinery fabrication, SS400 provides the flexibility and strength needed for a wide range of projects. Its chemical composition and mechanical properties make it a go-to material for engineers and builders alike.
