SMA490BP Weather Resistant Steel
SMA490BP Weather Resistant Steel: Full Data Sheet, Equivalents & Applications
Comprehensive technical data for SMA490BP weather resistant steel plate according to JIS G3114, including chemical composition, mechanical properties, thermal and electrical properties, international equivalent grades, similar materials, and application guide.
Welding, hot forging, cold forming, cutting, machining, thermal cutting (plasma, flame), normalizing
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SMA490BP Weather Resistant Steel Introduction
SMA490BP is a hot-rolled atmospheric corrosion-resistant steel for welded structures specified in JIS G3114. It belongs to the painted (P-type) weathering steel category, with minimum requirements for copper, chromium, and nickel to provide enhanced resistance to atmospheric corrosion compared to plain carbon steel. The designation '490' refers to a minimum tensile strength of 490 MPa, and 'B' indicates an impact toughness guarantee at 0°C (minimum 47 J). Typical applications include bridges, railway vehicles, building structures, and containers exposed to outdoor environments. The material is usually supplied in the as-rolled or normalized condition, and is suitable for welding, hot bending, and cold forming operations.
SMA490BP Weather Resistant Steel Chemical Composition
Chemical composition according to JIS G3114 for SMA490BP (painted type) steel. The addition of copper, chromium, and nickel ensures the formation of a dense, adherent rust layer that slows further corrosion. The composition is based on heat analysis and applies to product thickness up to 100 mm. Minor elements such as molybdenum, niobium, vanadium, and titanium may be added by agreement.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.18 | Maximum |
| Silicon (Si) | 0.15 – 0.55 | For painted type |
| Manganese (Mn) | ≤ 1.40 | Maximum |
| Phosphorus (P) | ≤ 0.035 | Maximum |
| Sulfur (S) | ≤ 0.035 | Maximum |
| Copper (Cu) | 0.30 – 0.50 | Corrosion resistance element |
| Chromium (Cr) | 0.45 – 0.75 | Corrosion resistance element |
| Nickel (Ni) | 0.05 – 0.30 | Optional, for improved toughness and rust stability |
| Molybdenum (Mo) | Optional | May be added by agreement for strength and corrosion |
| Niobium (Nb), Vanadium (V), Titanium (Ti) | Micro-alloying permitted | Grain refinement and precipitation strengthening |
SMA490BP Weather Resistant Steel Thermal & Electrical Physical Properties
Physical properties are representative of low-alloy weathering steels similar to SMA490BP. These values are not specified in JIS G3114 but are derived from published data for comparable steel types. They are applicable at room temperature unless otherwise indicated and may vary slightly depending on exact alloying and processing condition. Such data is useful for design calculations involving thermal stresses, heat transfer, or electrical conductivity.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | Ambient temperature |
| Modulus of Elasticity (E) | 200 – 210 | GPa | Room temperature |
| Shear Modulus (G) | 80 | GPa | Calculated from E and ν |
| Poisson's Ratio (ν) | 0.29 – 0.30 | - | Elastic range |
| Thermal Expansion Coefficient (α) | 11.0 – 12.5 | 10⁻⁶/K | 20 – 100°C |
| Thermal Expansion Coefficient (α) | 12.5 – 13.5 | 10⁻⁶/K | 20 – 400°C |
| Thermal Conductivity (λ) | 40 – 45 | W/(m·K) | At 20°C |
| Specific Heat Capacity (c) | 460 – 500 | J/(kg·K) | Room temperature |
| Electrical Resistivity (ρ_e) | 0.20 – 0.25 | μΩ·m | 20°C |
SMA490BP Weather Resistant Steel Mechanical Properties
Mechanical properties are based on JIS G3114 requirements for SMA490BP. The tensile test is performed on specimens taken transverse to the rolling direction unless otherwise agreed. Impact test is conducted on V-notch Charpy specimens at 0°C with a minimum absorbed energy of 47 J (average of three tests, with one individual value not below 30 J). For thickness below 5 mm, elongation is measured on gauge length JIS No.5.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 365 | MPa | Thickness t ≤ 16 mm |
| Yield Strength (ReH) | ≥ 355 | MPa | 16 < t ≤ 40 mm |
| Yield Strength (ReH) | ≥ 335 | MPa | 40 < t ≤ 75 mm |
| Yield Strength (ReH) | ≥ 325 | MPa | 75 < t ≤ 100 mm |
| Tensile Strength (Rm) | 490 – 610 | MPa | All thicknesses |
| Elongation (A) | ≥ 17 | % | t ≤ 16 mm, JIS No.5 specimen (gauge length 200 mm) |
| Elongation (A) | ≥ 19 | % | 16 < t ≤ 50 mm, JIS No.1A specimen (gauge length 200 mm) |
| Elongation (A) | ≥ 21 | % | 50 < t ≤ 100 mm, JIS No.1A specimen |
| Charpy Impact Energy (KV) | ≥ 47 (average), ≥ 30 (single) | J | 0°C, V-notch, longitudinal direction |
SMA490BP Weather Resistant Steel Fully Equivalent Material Standards & Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3114 | SMA490BW | Unpainted (weathering without coating) type, same mechanical properties, slight difference in Si and P range, otherwise equivalent in strength and impact |
| Europe | EN 10025-5 | S355J2W | Closest European weathering steel, matched on tensile (490–630 MPa) and impact at -20°C (J2), minor differences in alloy contents |
| USA | ASTM A588 / A588M | Grade B, Grade C | 50 ksi (345 MPa) min yield, 70 ksi (485 MPa) min tensile; practical replacement for SMA490BP with similar atmospheric resistance |
| China | GB/T 4171 | Q355GNH | 355 MPa min yield, 490–630 MPa tensile; designed for welded structures with weathering capability |
| International | ISO 4952 | Fe510B | Corresponds to weathering structural steel with minimum yield 355 MPa and tensile 490–630 MPa |
| India | IS 11587 | WR50B | Weathering steel with specified minimum yield 350 MPa and tensile 490–630 MPa |
SMA490BP Weather Resistant Steel Application Introduction
SMA490BP is primarily used in welded structural applications exposed to atmospheric conditions where a long maintenance-free service life is desired. The steel develops a stable, protective rust patina that reduces the corrosion rate to a very low level, eliminating or reducing the need for painting. Typical design considerations include allowance for thickness loss, drainage detailing, and avoidance of crevice corrosion. It can be fabricated by conventional methods: flame cutting, shearing, cold bending, and welding (using low-hydrogen processes and matching weathering steel consumables). Preheating may be required for thicker sections or low ambient temperatures.
Product Applications: Welded bridge girders and box sections, Railway car underframes and bodyside panels, Container frames and corner castings, Welded structural beams and columns for outdoor facilities, Wind turbine tower shells (where atmospheric corrosion resistance is required), Industrial plant structural steelwork
Processed into products: Main girder webs and flanges for bridges, Bolster and draft gear components in railcars, Stacking posts and corner fittings for containers, Support brackets and base plates for transmission towers, Flanges and stiffeners in wind tower sections, Welded joints in weather-exposed trusses
Application industries: Bridge construction (highway, railway, pedestrian bridges), Railway rolling stock (wagons, locomotive frames), Port and marine infrastructure (container terminals, quay structures), Building and civil engineering (exposed structural frames, canopies), Energy and transmission (transmission towers, wind turbine towers), Mining and industrial equipment (chutes, conveyors, structural supports)
SMA490BP Weather Resistant Steel Similar & Alternative Materials with Close Performance
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3114 | SMA490AW | Same strength class but unpainted (W) type; slightly different corrosion protection mechanism; impact at 0°C; often interchangeable |
| Japan | JIS G3106 | SM490A/B/C | Standard welded structural steel without weathering alloy; requires painting; similar mechanical properties but no atmospheric corrosion resistance |
| Europe | EN 10025-4 | S355M/ML | Thermomechanical rolled steel with 355 MPa yield and 470–630 MPa tensile; suitable for welded structures but lacks dedicated weathering elements |
| USA | ASTM A572 / A572M | Grade 50 | High-strength low-alloy structural steel; 345 MPa min yield, 450 MPa min tensile; no specified corrosion resistance, used with protective coating |
Notes:
Welding considerations: Use low-hydrogen electrodes (e.g., E49xx type for SMAW) or matching filler metals for weathering steel (e.g., ER80S-G for GMAW). For manual metal arc welding, JIS Z 3214 DA5046 or equivalent is recommended. Preheating at 40–100°C is advised when plate thickness exceeds 32 mm or at low ambient temperature. Corrosion performance: The protective patina forms best in alternating wet/dry cycles; continuous immersion or heavily polluted environments may require protective coating. Availability: Commonly supplied in plate thicknesses from 6 mm to 100 mm, with wider availability in standard structural sizes; contact suppliers for specific dimensions and tolerances per JIS G3193.
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