JIS G3106 SM490YA Steel for Welded Structures
JIS G3106 SM490YA Steel for LSAW Pipes – Composition, Properties & Equivalents
Comprehensive material data for SM490YA steel per JIS G3106, used in longitudinal submerged arc welded (LSAW) pipes: chemical composition, mechanical and thermal properties, international equivalents, and application guidance.
Weldable by all common methods, suitable for cutting, cold forming, machining
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JIS G3106 SM490YA Steel for Welded Structures Introduction
SM490YA is a Japanese structural steel grade specified in JIS G3106 for welded structures. It is a high-strength carbon-manganese steel with a minimum yield strength of 365 MPa (for thickness ≤16 mm) and tensile strength between 490 and 610 MPa. The 'Y' designation indicates that the steel is supplied with guaranteed yield point and the 'A' designates Charpy V-notch impact requirements at 0 °C (min 27 J). This steel offers excellent weldability, good toughness, and reliable mechanical properties, making it suitable for heavy fabrication. When manufactured into LSAW pipe (longitudinal submerged arc welded pipe), SM490YA is commonly used for
- structural applications
- offshore platforms
- line pipes
- pressure vessels
where high strength and low-temperature toughness are required. The steel can be delivered in as-rolled, normalized, or thermo-mechanically rolled condition depending on thickness and customer requirements.
JIS G3106 SM490YA Steel for Welded Structures Chemical Composition
The chemical composition of SM490YA is controlled to ensure good weldability and mechanical properties. Carbon equivalent (CEV) is often limited to improve weldability. Typical ladle analysis according to JIS G3106 is given below. Microalloying elements such as Nb, V, Ti may be added upon agreement.
| Element | Standard Value (max %) | Remarks |
|---|---|---|
| Carbon (C) | 0.20 | Ladle analysis |
| Silicon (Si) | 0.55 | Ladle analysis |
| Manganese (Mn) | 1.65 | Ladle analysis |
| Phosphorus (P) | 0.035 | Ladle analysis |
| Sulfur (S) | 0.035 | Ladle analysis |
| Carbon Equivalent (CEV) | 0.45 | Typically specified for thickness >25 mm, based on C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
JIS G3106 SM490YA Steel for Welded Structures Thermal and Electrical Physical Properties
The following physical properties are representative for carbon-manganese steel such as SM490YA at room temperature and near ambient conditions. They are not part of JIS G3106 mandatory requirements but are widely used for design and heat transfer calculations. Variations may occur with temperature.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20 °C |
| Modulus of Elasticity (E) | 205 | GPa | Ambient temperature |
| Shear Modulus (G) | 80 | GPa | Ambient temperature |
| Poisson's Ratio (ν) | 0.3 | – | Ambient temperature |
| Thermal Expansion Coefficient (α) | 12.0 | 10⁻⁶/K | 0 – 100 °C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | 20 °C |
| Specific Heat Capacity (c) | 460 | J/(kg·K) | 20 °C |
| Electrical Resistivity (ρₑ) | 0.18 | μΩ·m | 20 °C |
JIS G3106 SM490YA Steel for Welded Structures Mechanical Properties
Mechanical properties are guaranteed for plates and strips used to manufacture LSAW pipes. The values differ according to thickness. JIS G3106 specifies minimum yield strength (ReH) based on product thickness, tensile strength (Rm) in the range 490-610 MPa, and elongation measured on specified test pieces. Charpy V-notch impact energy is required at 0 °C. Bend tests are performed to confirm formability.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | min 365 | MPa | Thickness ≤16 mm |
| Yield Strength (ReH) | min 355 | MPa | 16 mm < thickness ≤40 mm |
| Yield Strength (ReH) | min 335 | MPa | 40 mm < thickness ≤75 mm |
| Yield Strength (ReH) | min 325 | MPa | 75 mm < thickness ≤100 mm |
| Yield Strength (ReH) | min 305 | MPa | 100 mm < thickness ≤160 mm |
| Yield Strength (ReH) | min 295 | MPa | 160 mm < thickness ≤200 mm |
| Tensile Strength (Rm) | 490 – 610 | MPa | All thicknesses, transverse specimens |
| Elongation (A) | min 14 | % | Thickness ≤5 mm, JIS No.5 test piece, longitudinal |
| Elongation (A) | min 19 (L) / min 17 (T) | % | 5 mm < thickness ≤16 mm, JIS No.1A, longitudinal/transverse |
| Elongation (A) | min 23 (L) / min 21 (T) | % | 16 mm < thickness ≤40 mm, JIS No.1A, longitudinal/transverse |
| Elongation (A) | min 25 (L) / min 23 (T) | % | Thickness >40 mm, JIS No.4, longitudinal/transverse |
| Charpy V-notch Impact Energy | min 27 (individual) | J | 0 °C, longitudinal, 10×10 mm specimen (or sub-size with agreed factors) |
| Bend Test | No cracks, inner diameter d = 1.5t | – | 180°, thickness ≤16 mm |
| Bend Test | No cracks, inner diameter d = 2.0t | – | 180°, 16 mm < thickness ≤100 mm |
JIS G3106 SM490YA Steel for Welded Structures Completely Equivalent Material Standards and Substitutable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM490YA | Original standard, base grade for LSAW pipe |
| South Korea | KS D 3515 | SM490YA | Identical technical delivery conditions |
| China | GB/T 1591 | Q460D | Very close chemistry and mechanical properties; 0 °C impact specified; often used interchangeably after technical review |
| European Union | EN 10025-2 | S460N | Normalized or rolled; impact at -20 °C may apply; slight differences in impact temperature but can be agreed |
| India | IS 2062 | E460 | Comparable strength and impact class, requires verification of full equivalence |
JIS G3106 SM490YA Steel for Welded Structures Application Introduction
SM490YA steel in LSAW pipe form is suited for demanding structural and pressure-containing applications. Its combination of high strength, good weldability, and guaranteed 0 °C toughness makes it a reliable choice where long-term integrity is essential. Typical usage environments include
- offshore topsides and jackets
- steel bridge tubular arches and chords
- high-pressure water and slurry pipelines
- penstocks in hydroelectric plants
- wind turbine tower sections
Product Applications: Longitudinal submerged arc welded (LSAW) pipes, Structural hollow sections (columns, piles), Pressure vessels and boiler shells, Bridge tubular members, Offshore jacket legs and bracings, Penstocks and hydropower spiral casings
Processed into products: Pipe spools and fittings (elbows, tees, reducers), Welded joints and girth welds in pipelines, Flanges and connectors, Stiffeners and ring girders, Pile sleeves and reinforcing ring plates, Manholes and nozzle necks in pressure equipment
Application industries: Oil & gas (onshore and offshore), Civil engineering and construction, Shipbuilding and marine structures, Renewable energy (wind, hydro), Water transmission and irrigation
JIS G3106 SM490YA Steel for Welded Structures Similar / Near-Equivalent Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A572 / A572M | Grade 65 | Higher yield (450 MPa min), tensile 550-690 MPa; impact properties not mandatory, can be ordered as supplementary requirement |
| USA | API 5L | Grade X52 (L360) | Pipe steel with min yield 360 MPa, tensile 460-760 MPa; widely used for LSAW pipelines; impact toughness at 0 °C optional in PSL2 |
| European Union | EN 10208-2 | L360MB | Pipeline steel similar to X52, with tighter chemistry; used for gas transmission pipes |
| Russia/CIS | GOST 19281 | 09G2S (09Г2С) | Classical shipbuilding structural steel; yield ~345 MPa, tensile 490-; not full equivalent but frequently used in similar applications; impact at -40 °C |
| International | ISO 630-2 | S460N | Structural steel, similar to EN S460N, general comparability |
Notes:
- LSAW pipe specifics: When SM490YA plates are formed into LSAW pipes, the welding process and post-weld heat treatment (if any) may alter local mechanical properties. It is common to qualify the weld procedure to ensure the joint meets the same toughness requirement as the base metal.
- Ultrasonic testing: JIS G3106 may require ultrasonic inspection for internal soundness when plates are intended for critical structural applications; additional NDE requirements for finished pipes should be defined in the pipe specification (e.g., API 5L or project specification).
- Lamellar tearing resistance: For welded joints subjected to through-thickness strain, through-thickness (Z-direction) properties might be specified separately per JIS G3199.
- Forming: Cold expansion after welding (for LSAW pipes) can increase yield strength by strain aging; thus, the base plate may be supplied at a slightly lower strength level to meet final pipe mechanical requirements.
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