SM490B High-Strength Weldable Structural Steel Plate
SM490B High-Strength Weldable Structural Steel Plate - JIS G3106 Properties & Equivalents
Comprehensive datasheet for JIS G3106 SM490B carbon and low-alloy high-strength steel plate, including chemical composition, mechanical and physical properties, international equivalents, and application guidance.
Hot rolling, normalizing, thermomechanical rolling, welding, cutting, bending, forming
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SM490B High-Strength Weldable Structural Steel Plate Introduction
SM490B is a weldable structural carbon and low-alloy high-strength steel plate defined in Japanese Industrial Standard JIS G3106. It is designed for welded structures requiring high strength, good formability, and reliable notch toughness at 0°C. The steel is typically supplied in hot-rolled, normalized, or thermomechanical rolled condition. Its carefully controlled chemical composition ensures excellent weldability, while minimum yield strengths (325–275 MPa depending on thickness) and tensile strength of 490–610 MPa provide structural efficiency.
- High strength-to-weight ratio for lightweight construction
- Guaranteed Charpy impact toughness at 0°C (minimum 27 J)
- Suitable for a wide range of plate thicknesses up to 200 mm
- Can be used in bridges, buildings, offshore structures, machinery, and shipbuilding
SM490B High-Strength Weldable Structural Steel Plate Chemical Composition
The chemical composition of SM490B steel according to JIS G3106. Elements are controlled to achieve the required mechanical properties and good weldability. Grain-refining elements such as Nb, V, or Ti may be added individually or in combination. The carbon equivalent (CE) or crack susceptibility parameter (Pcm) can be specified by agreement for improved welding performance.
| Element | Standard Value | Remarks |
|---|---|---|
| C (Carbon) | ≤ 0.20% | Ladle analysis |
| Si (Silicon) | ≤ 0.55% | |
| Mn (Manganese) | ≤ 1.65% | For thickness >50 mm, upper limit may be increased by agreement |
| P (Phosphorus) | ≤ 0.035% | |
| S (Sulfur) | ≤ 0.035% | |
| Others (Nb, V, Ti, etc.) | Optional | Grain-refining additions permitted |
SM490B High-Strength Weldable Structural Steel Plate Thermal and Electrical Physical Properties
Representative physical properties of SM490B carbon steel at room temperature. These values are typical for low-alloy structural steels and may vary slightly depending on exact composition and processing history. They are suitable for engineering calculations such as thermal expansion, heat transfer, and electrical conductivity assessments.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | at 20°C |
| Modulus of Elasticity (E) | 210 | GPa | at 20°C |
| Shear Modulus (G) | 81 | GPa | at 20°C |
| Poisson's Ratio (ν) | 0.3 | – | at 20°C |
| Thermal Expansion Coefficient (α) | 12.0 × 10⁻⁶ | K⁻¹ | 20–100°C |
| Thermal Conductivity (λ) | 51.9 | W/(m·K) | at 20°C |
| Specific Heat Capacity (c) | 486 | J/(kg·K) | at 20°C |
| Electrical Resistivity (ρₑ) | 0.15 – 0.20 | μΩ·m | at 20°C |
SM490B High-Strength Weldable Structural Steel Plate Mechanical Properties
Mechanical properties of SM490B plates as specified in JIS G3106. Yield strength values depend on plate thickness. Tensile strength range applies to all thicknesses. Elongation requirements vary with thickness and test piece. Charpy impact energy is guaranteed at 0°C with minimum average 27 J (longitudinal, V-notch). Bend test confirms ductility.
| Property | Required Value | Unit | Test Condition / Thickness |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 325 | MPa | t ≤ 16 mm |
| Yield Strength (ReH) | ≥ 315 | MPa | 16 < t ≤ 40 mm |
| Yield Strength (ReH) | ≥ 295 | MPa | 40 < t ≤ 75 mm |
| Yield Strength (ReH) | ≥ 295 | MPa | 75 < t ≤ 100 mm |
| Yield Strength (ReH) | ≥ 285 | MPa | 100 < t ≤ 160 mm |
| Yield Strength (ReH) | ≥ 275 | MPa | 160 < t ≤ 200 mm |
| Tensile Strength (Rm) | 490 – 610 | MPa | all thicknesses |
| Elongation (A) | ≥ 17 | % | t ≤ 16 mm, JIS No.5 test piece (gauge length 50 mm) |
| Elongation (A) | ≥ 21 | % | 16 < t ≤ 50 mm, JIS No.1A test piece (gauge length 200 mm) |
| Elongation (A) | ≥ 23 | % | t > 50 mm, JIS No.10 test piece (gauge length 50 mm) |
| Charpy Impact Energy (KV₂) | ≥ 27 | J | at 0°C, longitudinal, V-notch, average of 3 specimens |
| Bend Test (180°) | No cracks | – | t ≤ 16 mm: inside radius = 1.5t; 16 < t ≤ 100 mm: 2.0t; >100 mm: 2.5t |
SM490B High-Strength Weldable Structural Steel Plate Full Equivalent Material Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM490B | Original standard grade |
| China | GB/T 1591 | Q345C | Equivalent yield strength, 0°C impact, slight composition differences |
| Europe | EN 10025-2 | S355J0 | Matching strength range and 0°C impact toughness |
| USA | ASTM A572/A572M | Grade 50 + impact test | Strength similar; 0°C impact must be specially agreed |
| International | ISO 4950-2 | E355DD | High yield strength structural steel, DD quality with 0°C impact |
| Korea | KS D 3515 | SM490B | Identical designation, technically equivalent to JIS G3106 |
SM490B High-Strength Weldable Structural Steel Plate Application Introduction
SM490B steel is extensively used in welded structural applications where a combination of high strength, good weldability, and moderate toughness is essential. It performs reliably under both static and dynamic loads. The guaranteed 0°C impact toughness makes it suitable for main structural members in bridges, buildings, and offshore platforms located in temperate climates. Plates can be processed by thermal cutting, cold forming, and all common arc welding methods. Preheating and post-weld heat treatment may be applied according to thickness and fabrication codes.
Product Applications: Steel bridge girders, decks, and trusses, High-rise building columns, beams, and braces, Offshore platform structural modules, Boom and arm of excavators and cranes, Railway carriage underframes and bogies, Ship hull plates and stiffeners, Storage tank shells and roofs, Transmission towers and monopoles
Processed into products: Welded I-beams and box section columns, Flanges and web plates for plate girders, Reinforcement ribs and stiffeners, Base plates and anchor bolt assemblies, Pile caps and connecting plates, Heavy-duty frame members and supports, Transition pieces and doubler plates
Application industries: Bridge Construction, Building and Civil Engineering, Offshore and Marine Structures, Industrial Machinery, Railway Vehicles, Shipbuilding, Pressure Vessels (non-high temperature), Mining and Earthmoving Equipment
SM490B High-Strength Weldable Structural Steel Plate Similar / Near-Equivalent Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 1591 | Q345B | Slightly lower impact temperature (20°C); verify toughness requirement |
| Europe | EN 10025-2 | S355J2 | Better low-temperature toughness (-20°C), all other properties comparable |
| USA | ASTM A709/A709M | Grade 50 (0°C) | Structural steel for bridges, impact test at 0°C specified |
| Russia | GOST 19281 | 17G1S | Similar strength category, used for welded structures |
| India | IS 2062 | E350 C | Minimum yield 350 MPa, C quality with 0°C impact |
Notes:
Delivery conditions may include hot-rolled, normalized, or thermomechanical rolled (TMCP) state as agreed between the manufacturer and purchaser. For enhanced weldability, supplementary requirements such as carbon equivalent (CE) limits or Pcm control can be specified. Ultrasonic testing, magnetic particle inspection, and other non-destructive examinations can be carried out according to additional specifications. When ordering, the purchaser should state the required thickness, width, length, quantity, and any optional requirements (e.g., impact temperature, supplementary tests, surface condition).
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