Steel SMA490W-N (Normalized)
Heat-treated state
Choose for thick plate or when guaranteed −5 °C/0 °C Charpy values and fine grain are specified.
Values for the N condition
Other SMA490W tempers and conditions
SMA490W is listed in 3 conditions; see the grade overview at SMA490W.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
NThis page 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 |
What is SMA490W-N?
SMA490W-N is SMA490W heat treated to N — choose for thick plate or when guaranteed −5 °C/0 °C Charpy values and fine grain are specified. SMA490W-N has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 68% of steel grades. Elongation at break is 26% and the elastic modulus is 205 GPa (29.7 Msi). SMA490W-N 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). AR-HR is the default condition FabDigit quotes; N is available on request or by drawing note.
Advantages
- Good corrosion resistance — 32/100, better than 96% of steel grades
- Forms and bends easily — 68/100, better than 83% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
- Readily welded — 82/100, better than 81% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
SMA490W-N properties
Typical room-temperature values for SMA490W-N; 23 are specific to this condition. Other listed values are SMA490W reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SMA490W-N 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-N has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 68% of steel grades. Elongation at break is 26% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SMA490W-N 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-N 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-N 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-N's machinability is good (57/100, better than 71% of steel grades); weldability very good (82/100); formability good (68/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SMA490W-N
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.
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.
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 | — |
SMA490W-N — frequently asked
What is SMA490W-N used for?
SMA490W-N 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-N?
SMA490W-N has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is SMA490W-N easy to machine?
Reasonably — machinability is rated good (57/100, better than 71% 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-N be welded?
Yes — weldability is rated very good (82/100). 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-N?
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-N 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-N?
SMA490W-N 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.