JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil
JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil - Full Material Data
Technical data sheet for JIS G3106 SM490YA carbon and low-alloy high-strength structural steel coil. Covers chemistry, mechanical properties, thermal and electrical data, international equivalents, similar grades, and application guide.
Welding (SMAW, GMAW, SAW), hot forming, cold forming, gas cutting, plasma cutting, machining, bending, deep drawing
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JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil Introduction
JIS G3106 SM490YA is a high-strength, low‑alloy structural steel produced as hot‑rolled coil, plate, or strip for welded structures. It belongs to the SM490 family and offers a minimum yield strength of 365 MPa in thinner gauges, excellent weldability, and guaranteed notch toughness at 0 °C.
- Grade suffix 'YA' indicates a fine‑grain killed steel with mandatory Charpy impact testing at 0 °C (min. 27 J average).
- Ideal for building frames, bridges, ship hulls, offshore decks and pressure vessels where high strength and reliable low‑temperature toughness are required.
- Often microalloyed with niobium, vanadium or titanium for grain refinement and strength enhancement.
Carbon equivalent (CEV) is controlled ≤0.39 % for thickness up to 50 mm, ensuring good weldability without excessive preheating. The steel is typically supplied in the as‑rolled condition, but normalizing may be applied for thicker sections or specific applications.
JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil Chemical Composition
The chemical composition of SM490YA as specified in JIS G3106 ensures a good balance of strength, toughness and weldability. Carbon is limited to 0.20 % to avoid hardening in the heat‑affected zone, while manganese up to 1.65 % provides solid‑solution strengthening. Phosphorus and sulfur are kept low for cleanliness and ductility.
- Niobium, vanadium and titanium may be added singly or in combination up to 0.05 % each for grain refinement and precipitation strengthening.
- Elements not listed, such as chromium, nickel, copper and molybdenum, are not specified but may appear as residual up to 0.30 % each (except Cr ≤ 0.30 %, Ni ≤ 0.30 %, Cu ≤ 0.35 %, Mo ≤ 0.10 %), not affecting the properties.
Carbon equivalent value (CEV) is controlled: CEV ≤ 0.39 % for t ≤ 50 mm and ≤ 0.41 % for 50 < t ≤ 100 mm.
| Chemical element | Standard value (max. %) | Remarks |
|---|---|---|
| C | ≤ 0.20 | Ladle analysis |
| Si | ≤ 0.55 | — |
| Mn | ≤ 1.65 | — |
| P | ≤ 0.035 | — |
| S | ≤ 0.035 | — |
| Nb (Niobium) | ≤ 0.05 | Optional, alone or combined |
| V (Vanadium) | ≤ 0.05 | Optional, alone or combined |
| Ti (Titanium) | ≤ 0.05 | Optional, alone or combined |
JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil Thermal and Electrical Physical Properties
The following physical constants are indicative for carbon‑manganese structural steels similar to SM490YA and can be used for engineering calculations. Actual values may slightly vary with processing condition and temperature. Thermal expansion and conductivity are within the range expected for low‑alloy steels, enabling standard design procedures for welded structures.
- All values apply at room temperature unless a temperature range is indicated.
- Electrical resistivity is typical for ferritic‑pearlitic structural steel.
| Property | Value | Unit | Condition / temperature |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20 °C |
| Modulus of elasticity (E) | 210 | GPa | 20 °C, tensile |
| Shear modulus (G) | 80 | GPa | 20 °C |
| Poisson's ratio (ν) | 0.30 | – | Elastic range |
| Thermal expansion coefficient (α) | 12.0 | 10^-6/K | 20 °C – 100 °C |
| Thermal expansion coefficient (α) | 12.5 | 10^-6/K | 20 °C – 200 °C |
| Thermal expansion coefficient (α) | 13.0 | 10^-6/K | 20 °C – 300 °C |
| Thermal conductivity (λ) | 50 | W/(m·K) | 20 °C |
| Specific heat capacity (cₚ) | 486 | J/(kg·K) | 20 °C |
| Electrical resistivity (ρₑ) | 0.18 | μΩ·m | 20 °C |
JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil Mechanical Properties
Mechanical properties are guaranteed from the mill according to JIS G3106. The steel exhibits appreciable yield and tensile strength with good ductility and high‑energy absorption at low temperature. Charpy V‑notch impact tests are mandatory at 0 °C, which is key for primary structural applications. Elongation values differ with test gauge length and thickness; use the appropriate row for design.
- Bend test (180°) ensures the material withstands cold forming without cracking.
- Values for thickness >100 mm are subject to agreement.
| Property | Value | Unit | Condition / thickness range |
|---|---|---|---|
| Yield strength (ReH) | ≥ 365 | MPa | t ≤ 16 mm |
| Yield strength (ReH) | ≥ 355 | MPa | 16 < t ≤ 40 mm |
| Tensile strength (Rm) | 490 – 610 | MPa | t ≤ 100 mm |
| Elongation (A) | ≥ 15 | % | G.L. 50 mm, t ≤ 5 mm |
| Elongation (A) | ≥ 19 | % | G.L. 5.65√S, 5 < t ≤ 16 mm |
| Elongation (A) | ≥ 19 | % | Test piece 1A (G.L. 5D), 16 < t ≤ 40 mm |
| Charpy impact energy (KV₂, average) | ≥ 27 | J | Test temp. 0 °C, V‑notch, t ≤ 16 mm |
| Charpy impact energy (KV₂, individual) | ≥ 20 | J | Test temp. 0 °C, V‑notch, t ≤ 16 mm |
| Bend test (180°) | No crack | – | Mandrel diameter: 1.0 × t, t ≤ 16 mm |
| Bend test (180°) | No crack | – | Mandrel diameter: 1.5 × t, 16 < t ≤ 100 mm |
JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil Fully Equivalent International Standards and Alternative Designations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM490YA | Original standard; impact 0 °C 27 J |
| USA | ASTM A572 / A572M | Grade 50 [with Charpy S5] | Closest match when 0 °C 27 J supplemental requirement is agreed |
| USA | ASTM A709 / A709M | Grade 50 [Zone 2] | Bridge steel with Charpy at 4 °C (similar toughness level) |
| Europe | EN 10025-2 | S355J0 | Impact at 0 °C 27 J; nearly identical strength and chemistry |
| China | GB/T 1591-2018 | Q355C (old Q345C) | Impact at 0 °C 34 J; very close in properties |
| India | IS 2062:2011 | E350 B | Impact at 0 °C 27 J; microalloyed structural steel |
JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil Application Introduction
SM490YA is engineered for welded heavy structures where high strength and dependable notch toughness at 0 °C are essential. Its good formability and weldability make it suitable for a wide range of manufacturing processes: cold bending, flame cutting, submerged‑arc welding, and robotic welding.
- Typical fabrication includes welding with preheat for thickness >30 mm to avoid hydrogen cracking.
- Can be used in the as‑rolled or normalised condition; normalising refines grain size and improves toughness further.
- Often selected for projects that require CE marking or third‑party inspection, thanks to guaranteed impact properties.
Product Applications: Multi‑storey building frames and column‑beam connections, Highway and railway bridge girders, trusses, and decks, Ship hull plates, stiffeners, and bulkheads, Jack‑up rig legs, offshore platform modules, and helidecks, Penstocks and spiral casings for hydropower plants, Storage tank shells (oil, water, chemical), Wind turbine tower sections and foundation inserts
Processed into products: Welded H‑beams and box columns, Gusset plates, splice plates, and stiffening ribs, Crane main chords, outriggers, and booms, Heavy‑duty mining truck frames and dump bodies, Turret rings and slewing rings for crawler cranes, Base frames and mountings for stationary engines and compressors, Mooring bollards and harbour crane pedestals
Application industries: Building and civil engineering construction, Bridge engineering, Shipbuilding and marine structures, Offshore oil & gas platforms, Pressure vessel and boiler fabrication, Heavy machinery and transport equipment
JIS G3106 SM490YA High-Strength Weldable Structural Steel Coil Similar Materials – Close Substitutes with Slight Property Differences
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM490A | Same base without guaranteed impact test |
| Japan | JIS G3106 | SM490B | Impact at -10 °C 27 J, slightly better toughness |
| Europe | EN 10025-2 | S355J2 (+N) | Impact at -20 °C 27 J; often used when lower temperature toughness is needed |
| China | GB/T 1591 | Q345D / Q355D | Impact at -20 °C 27 J, similar to S355J2 |
| USA | ASTM A572 | Grade 50 [without Charpy] | Does not guarantee low‑temperature Charpy; often ordered with S5 if required |
| Russia | GOST 19281 | 09G2S | Similar C‑Mn‑Si steel, impact at -40 °C but with lower yield (~325 MPa) |
Notes:
Carbon equivalent (CEV) control: CEV ≤ 0.39 % for t ≤ 50 mm, ≤ 0.41 % for 50 < t ≤ 100 mm (CEV = C + Mn/6 + Si/24 + Ni/40 + Cr/5 + Mo/4 + V/14). Weldability: Preheat typically 50–100 °C for thickness up to 30 mm; interpass temperature ≤ 200 °C. Low‑hydrogen electrodes or wires recommended. Corrosion resistance: Copper may be specified as a residual for improved atmospheric corrosion resistance (Cu ≤ 0.35 %, as per JIS G3106). If higher weathering capability is needed, consider JIS G3114 SMA490 series. Ultrasonic testing: May be agreed according to JIS G0801 or EN 10160 for critical applications. Dimensional tolerances: Conforms to JIS G3193 for hot‑rolled sheets and strips.
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