JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate
JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate | Properties & Equivalents
Complete technical data of JIS G3106 SM490YA thermomechanically rolled steel plate: chemical composition, mechanical properties, thermal and electrical properties, international equivalents and applications.
Hot rolling, thermomechanical rolling, cutting, welding, forming, machining
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JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate Introduction
JIS G3106 SM490YA is a thermomechanically rolled, weldable fine-grained structural steel plate standardized under Japanese Industrial Standards for welded structures. It offers a minimum yield strength of 365 MPa for thicknesses up to 16 mm and tensile strength in the range of 490–610 MPa. The suffix 'Y' denotes enhanced yield strength achieved through controlled rolling, while 'A' indicates guaranteed Charpy V-notch impact toughness of at least 27 J at 0°C. Microalloying with Al, Nb, V or Ti ensures a fine grain structure, improving both strength and low-temperature toughness. SM490YA is widely used in bridges, shipbuilding, offshore platforms, construction machinery, and general heavy fabrication where reliable weldability and ductility are essential.
JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate Chemical Composition
The chemical requirements for SM490YA are defined in JIS G3106. For this thermomechanically rolled grade, the steel shall contain at least one grain-refining element such as Al, Nb, V, or Ti in the amounts shown. The composition is balanced to ensure high strength, good weldability, and excellent notch toughness.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| C | ≤ 0.20 | Depending on deoxidation method, may be adjusted |
| Si | ≤ 0.55 | |
| Mn | ≤ 1.65 | For thickness >100 mm, ≤1.65% |
| P | ≤ 0.035 | |
| S | ≤ 0.035 | |
| Total Al | ≥ 0.020 | If used as grain-refining element |
| Nb | ≥ 0.015 | If used as grain-refining element |
| V | ≥ 0.020 | If used as grain-refining element |
| Ti | ≥ 0.010 | If used as grain-refining element |
JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate Thermal and Electrical Physical Properties
The physical constants provided are typical values for low-alloy high-strength steels of this grade at room temperature unless noted otherwise. They are not specified in JIS G3106 but are widely accepted for design calculations.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Modulus of Elasticity (E) | 210 | GPa | At 20 °C, tensile |
| Shear Modulus (G) | approx. 80 | GPa | At 20 °C |
| Poisson's Ratio (ν) | 0.30 | At 20 °C | |
| Thermal Expansion Coeff. (α) | 12.0 × 10⁻⁶ | K⁻¹ | 20–100 °C |
| Thermal Expansion Coeff. (α) | 13.0 × 10⁻⁶ | K⁻¹ | 20–200 °C |
| Thermal Expansion Coeff. (α) | 14.0 × 10⁻⁶ | K⁻¹ | 20–400 °C |
| Thermal Conductivity (λ) | 53 | W/(m·K) | At 20 °C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | At 200 °C |
| Specific Heat Capacity (c) | approx. 460 | J/(kg·K) | 20–200 °C |
| Electrical Resistivity (ρₑ) | approx. 0.15–0.20 | μΩ·m | At 20 °C |
JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate Mechanical Properties
Mechanical properties are evaluated according to JIS G3106. Yield strength, tensile strength, elongation, bend test, and Charpy impact values depend on the plate thickness and test orientation. The following values are the minimum requirements for longitudinal specimens unless otherwise stated.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 365 | MPa | Thickness ≤ 16 mm |
| Yield Strength (ReH) | ≥ 355 | MPa | 16 < thickness ≤ 40 mm |
| Yield Strength (ReH) | ≥ 335 | MPa | 40 < thickness ≤ 75 mm |
| Yield Strength (ReH) | ≥ 325 | MPa | 75 < thickness ≤ 100 mm |
| Yield Strength (ReH) | ≥ 315 | MPa | 100 < thickness ≤ 160 mm |
| Yield Strength (ReH) | ≥ 315 | MPa | 160 < thickness ≤ 200 mm |
| Tensile Strength (Rm) | 490–610 | MPa | All thicknesses |
| Elongation (A) | ≥ 15 | % | No.5 test piece, t ≤ 5 mm |
| Elongation (A) | ≥ 17 | % | No.5 test piece, 5 < t ≤ 16 mm |
| Elongation (A) | ≥ 21 | % | 1A test piece, 16 < t ≤ 50 mm |
| Elongation (A) | ≥ 23 | % | No.10 test piece, 50 < t ≤ 100 mm |
| Bend Test (180°) | Inner radius 1.5 × t, no cracks | Thickness ≤ 25 mm | |
| Bend Test (180°) | Inner radius 2.0 × t, no cracks | Thickness > 25 mm | |
| Charpy Impact Energy (KV₂) | Mean ≥ 27, single min ≥ 19 | J | Longitudinal, 0 °C, V-notch, 10×10 mm |
JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate Fully Equivalent Material Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM490A / SM490B / SM490C | Same base composition; differ in impact test temperature (A: 0°C, B: 0°C, C: 0°C optional?). SM490YA is thermomechanically rolled with guaranteed fine grain and higher yield. |
| European Union | EN 10025-2 | S355J2 (+N/+M) | Close yield and tensile ranges; S355J2 impact at -20°C; SM490YA may be substituted if agreed, noting slightly higher minimum yield above 16 mm. |
| USA | ASTM A572/A572M | Grade 50 [345] | Minimum yield 345 MPa, tensile 450 MPa; SM490YA provides higher strength and requires 0°C impact; often used in similar structural applications with adjustments. |
| China | GB/T 1591 | Q355D / Q355E | Chemical composition and mechanical properties are comparable; Q355D has 0°C impact, Q355E -20°C; SM490YA can replace with thickness and design review. |
JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate Application Introduction
SM490YA is engineered for welded steel structures requiring high reliability and toughness at moderate temperatures. Thanks to its thermomechanically rolled fine-grained microstructure, it exhibits excellent weldability without excessive preheating, good formability, and uniform mechanical properties across large plates. Typical applications include:
Product Applications: Welded plate girders and built-up sections, Bridge deck and stiffener plates, Ship plates and ship structural parts, Offshore platform decks and beams, Construction machinery booms and crane jibs, Wind turbine tower flanges and shells, Pressure vessel shells (design outside ASME impact ranges)
Processed into products: Flanges and webs of welded beams, Column splice plates, Crane rail beams and runway girders, Base plates and anchor boxes, Bulkhead stiffeners and brackets, Heavy-duty machine frames and supports, Excavator and loader arms
Application industries: Bridge construction (main girders, box sections, cross-beams), Shipbuilding (hulls, decks, bulkheads), Offshore and marine structures (platforms, jacket legs), Building and civil engineering (high-rise columns, trusses, base plates), Heavy machinery and cranes (booms, frames, chassis), Pressure vessel shells and storage tanks (non-cryogenic), Railway and transportation (wagon frames, bridges)
JIS G3106 SM490YA Carbon & Low-Alloy High-Strength Steel Plate Similar / Alternative Materials Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM490YB / SM490YC | Higher impact toughness class (YB: 0°C? YC: 0°C?). Strengths identical; can be used when stricter impact requirements are not needed. |
| Japan | JIS G3106 | SM520B / SM520C | Higher tensile strength (520–640 MPa) with slightly lower elongation; suitable if higher strength is required. |
| European Union | EN 10025-4 | S355M / S355ML | Thermomechanically rolled with matching yield/tensile; S355ML has improved low-temperature toughness. |
| USA | ASTM A572/A572M | Grade 50 [345] modified | With modified processing to achieve fine grain and 0°C impact, can approximate SM490YA performance. |
| International | ISO 4950-2 | E355 | High yield strength structural steel with similar base composition; refer to agreement for impact and rolling condition. |
Notes:
Additional remarks:
- The steel shall be killed and microalloyed with fine-grain practice (Al, Nb, V or Ti).
- Welding consumables shall match the strength and toughness class; low-hydrogen processes are recommended.
- Post-weld heat treatment (PWHT) is not mandatory, but stress relieving may be applied if specified.
- For thicknesses larger than 200 mm, separate inquiry is required to the manufacturer.
- The Charpy values apply to standard 10×10 mm specimens; for sub-size specimens, minimum energy values shall be proportionally reduced per JIS G0307 or agreed.
- Dimensions and tolerances follow JIS G3193 for hot-rolled steel plates.
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