Steel SMA490W
SMA490W is the Japanese weathering-grade HSLA structural steel (comparable to A588 and Q355GNH), copper- and chromium-alloyed for uncoated exposed use, with 390 MPa yield, 540 MPa tensile, 24 % elongation and about 160 HB.
Reference datasheet — SMA490W is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AR-HR condition
SMA490W tempers and conditions
SMA490W is supplied in 3 conditions, soft to hard. AR-HR is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Normalized | Choose for thick plate or when guaranteed −5 °C/0 °C Charpy values and fine grain are specified. | 380 | 530 | 26 | 155 HB | 7.8 % IACS |
AR-HRDefault As-Rolled | Standard stocked condition for weathering-steel plate, strip and shapes up to moderate thickness. | 390 | 540 | 24 | 160 HB | 7.8 % IACS |
Thermomechanically controlled processed | Pick for heavy weathering plate needing low carbon equivalent, better weldability and high toughness without normalizing. | 400 | 550 | 26 | 165 HB | 7.8 % IACS |
Supply forms, finishes and certifications
Ways SMA490W is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CR-STRIP | Cold Rolled strip / thin sheet | Supply form |
PATINA | Pre-weathered / accelerated-patina finish | Surface finish |
What is SMA490W?
SMA490W is the Japanese weathering-grade HSLA structural steel (comparable to A588 and Q355GNH), copper- and chromium-alloyed for uncoated exposed use, with 390 MPa yield, 540 MPa tensile, 24 % elongation and about 160 HB. It is supplied as hot-rolled plate and cold-rolled strip in as-rolled, normalized, TMCP and pre-patinated conditions for bridges, highway structures and exposed frames. As with all weathering steels the patina needs alternating wetting and drying, so chloride exposure, sheltered wet details or buried sections require paint or metallizing, and rust run-off can stain adjacent concrete. S355J2W is the closest European equivalent. SMA490W has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,470°C (2,678 °F). SMA490W has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 64% of steel grades. Elongation at break is 24% and the elastic modulus is 205 GPa (29.7 Msi).
What is SMA490W used for?
- bridges
- highway structures
- exposed steel frameworks
Advantages
- Good corrosion resistance — 32/100, better than 96% of steel grades
- Forms and bends easily — 65/100, better than 81% of steel grades
- Readily welded — 80/100, better than 79% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
SMA490W properties
Typical room-temperature values for SMA490W-AR-HR; bars are the position among steel grades.
Physical3
SMA490W has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,470°C (2,678 °F).
Mechanical16
SMA490W has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 64% of steel grades. Elongation at break is 24% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SMA490W is rated for continuous service to 350°C (662 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
SMA490W conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), better than 96% of steel grades.
Sustainability4
Producing a kilogram of SMA490W takes about 26 MJ of energy and emits 2.1 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 25%.
Manufacturability6
SMA490W's machinability is good (55/100, better than 62% of steel grades); weldability very good (80/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. SMA490W is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SMA490W
Is SMA490W easy to machine?
Drills, saws and mills like A588/Q345 plate at ~60 % of 1212 speeds; use rigid setups and sharp carbide, expect mildly gummy chips from the higher Cu/Cr.
Can SMA490W be welded?
Readily welded by SMAW/GMAW/SAW with weathering-matched consumables (e.g. E7018-W1/ER80S-G) so the weld patinas with the base; preheat 50–100 °C for thick or restrained joints and keep hydrogen low.
Can SMA490W be formed, bent or molded?
Hot-rolled plate bends cold at ≥3t inside radius across the rolling direction; hot forming is fine but avoid finishing below ~750 °C to protect toughness.
SMA490W chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CJIS G 3114 SMA490 W/P | ≤ 0.18 | 0.13 |
| Si | 0.15 – 0.65 | 0.4 |
| Mn | ≤ 1.4 | 1.1 |
| PW type; P type allows 0.07–0.15 P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.01 |
| Cupatina former | 0.3 – 0.5 | 0.35 |
| Cr | 0.45 – 0.75 | 0.6 |
| Ni | 0.05 – 0.3 | 0.15 |
| Mooptional/residual | ≤ 0.1 | |
| Voptional micro-alloy | ≤ 0.1 | |
| Fe | balance |
What surface finishes work on SMA490W?
Normally left bare to develop the protective patina — grit-blast to remove mill scale and design free-draining details; if painted, treat as ordinary structural steel with an epoxy/PU system, and manage rust runoff staining on adjacent concrete.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel SMA490W in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- A588Q355GNH
How much does SMA490W cost?
SMA490W is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
SMA490W — frequently asked
What is SMA490W used for?
SMA490W is typically used for bridges, highway structures and exposed steel frameworks. In short: japanese weathering structural grade; maintenance-free bridge steel; A588-class atmospheric resistance.
What is the yield strength of SMA490W?
SMA490W has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 64% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is SMA490W easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Drills, saws and mills like A588/Q345 plate at ~60 % of 1212 speeds; use rigid setups and sharp carbide, expect mildly gummy chips from the higher Cu/Cr.
Can SMA490W be welded?
Yes — weldability is rated very good (80/100). Readily welded by SMAW/GMAW/SAW with weathering-matched consumables (e.g. E7018-W1/ER80S-G) so the weld patinas with the base; preheat 50–100 °C for thick or restrained joints and keep hydrogen low.
What surface finishes work on SMA490W?
Normally left bare to develop the protective patina — grit-blast to remove mill scale and design free-draining details; if painted, treat as ordinary structural steel with an epoxy/PU system, and manage rust runoff staining on adjacent concrete.
Can SMA490W be formed, bent or molded?
Hot-rolled plate bends cold at ≥3t inside radius across the rolling direction; hot forming is fine but avoid finishing below ~750 °C to protect toughness.
What is the maximum service temperature of SMA490W?
SMA490W is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SMA490W AR-HR and SMA490W-N?
AR-HR is the default condition — standard stocked condition for weathering-steel plate, strip and shapes up to moderate thickness. N: choose for thick plate or when guaranteed −5 °C/0 °C Charpy values and fine grain are specified. Yield strength is 390 MPa in AR-HR versus 380 MPa in N.
How much does SMA490W cost?
SMA490W is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- JIS G 3114 — Hot-rolled atmospheric corrosion resisting steels for welded structures — JSA (2016)
- ASTM A588/A588M — High-Strength Low-Alloy Structural Steel with Atmospheric Corrosion Resistance — ASTM (2019)
- GB/T 4171 — Atmospheric corrosion resisting structural steel (Q355GNH) — SAC (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13C — Corrosion: Environments and Industries (weathering steels) — ASM International (2006)
- Weathering steel plate (SMA490AW/BW/CW) datasheet — Nippon Steel (2022)
- Q355GNH/SMA490W — Mysteel / 1688 (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.