Steel SM490A-N (Normalized)
Heat-treated state
JIS SM490A · ASTM A572 Gr 50
Pick for thick plate or after hot forming when uniform fine grain and better notch toughness are required.
Values for the N condition
Other SM490A tempers and conditions
SM490A is listed in 4 conditions; see the grade overview at SM490A.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Stress relieved | Use for heavy welded fabrications needing dimensional stability and reduced residual stress before machining. | 350 | 520 | 25 | 148 HB | 10 % IACS |
NThis page Normalized | Pick for thick plate or after hot forming when uniform fine grain and better notch toughness are required. | 360 | 530 | 25 | 150 HB | 10 % IACS |
ARDefault As hot rolled | Standard stocked plate/section condition for general welded structures at ambient service temperature. | 365 | 540 | 22 | 155 HB | 10 % IACS |
Thermomechanically controlled processed | Choose for thick bridge/offshore plate where low carbon equivalent, better weldability and higher toughness are needed at the same strength. | 385 | 545 | 24 | 160 HB | 10 % IACS |
What is SM490A-N?
SM490A-N is SM490A heat treated to N — pick for thick plate or after hot forming when uniform fine grain and better notch toughness are required. SM490A-N has a yield strength of 360 MPa (52.2 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 72% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi). SM490A-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). AR is the default condition FabDigit quotes; N is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 135 MPa·√m (122.9 ksi·√in), better than 93% of steel grades
- Readily welded — 90/100, better than 90% of steel grades
- Conducts heat well — 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades
- Forms and bends easily — 70/100, better than 86% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
SM490A-N properties
Typical room-temperature values for SM490A-N; 23 are specific to this condition. Other listed values are SM490A reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SM490A-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
SM490A-N has a yield strength of 360 MPa (52.2 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 72% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SM490A-N is rated for continuous service to 350°C (662 °F). It conducts heat at 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
SM490A-N conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SM490A-N takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
SM490A-N's machinability is good (60/100, better than 83% of steel grades); weldability excellent (90/100); formability very good (70/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SM490A-N
Is SM490A easy to machine?
Machines like ordinary C-Mn structural steel at ~60 % of AISI 1212; use rigid setups and coolant, expect stringy chips in as-rolled plate.
Can SM490A be welded?
Excellent weldability by SMAW/GMAW/SAW with ~E49xx / ER70S-class consumables; preheat 50–100 °C for thick sections or high restraint.
Can SM490A be formed, bent or molded?
Cold bend at r ≥ 2t (≥3t across the rolling direction for thick plate); hot forming 900–1050 °C followed by normalizing is preferred for tight radii.
What surface finishes work on SM490A?
Must be protected — blast to Sa 2½ then epoxy/zinc-rich primer, hot-dip galvanize, or metallize; no anodizing, polishing is only for cosmetic ground plate.
SM490A 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 |
|---|---|---|
| C≤0.20 for t≤50 mm; ≤0.22 for t>50 mm (JIS G3106) | ≤ 0.2 | 0.16 |
| Si | ≤ 0.55 | 0.3 |
| Mn≤1.65 (older editions 1.60); ≥0.60 for shapes | ≤ 1.65 | 1.35 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Fe | balance | — |
SM490A-N — frequently asked
What is SM490A-N used for?
SM490A-N is typically used for bridges, heavy structures, cranes and shipbuilding. In short: A572 Gr 50 equivalent; weldable at 365 MPa yield; needs preheat when thick.
What is the yield strength of SM490A-N?
SM490A-N has a typical yield strength of 360 MPa (52.2 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 72% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is SM490A-N easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machines like ordinary C-Mn structural steel at ~60 % of AISI 1212; use rigid setups and coolant, expect stringy chips in as-rolled plate.
Can SM490A-N be welded?
Yes — weldability is rated excellent (90/100). Excellent weldability by SMAW/GMAW/SAW with ~E49xx / ER70S-class consumables; preheat 50–100 °C for thick sections or high restraint.
What surface finishes work on SM490A-N?
Must be protected — blast to Sa 2½ then epoxy/zinc-rich primer, hot-dip galvanize, or metallize; no anodizing, polishing is only for cosmetic ground plate.
Can SM490A-N be formed, bent or molded?
Cold bend at r ≥ 2t (≥3t across the rolling direction for thick plate); hot forming 900–1050 °C followed by normalizing is preferred for tight radii.
What is the maximum service temperature of SM490A-N?
SM490A-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 SM490A-AR and SM490A TMCP?
AR is the default condition — standard stocked plate/section condition for general welded structures at ambient service temperature. TMCP: choose for thick bridge/offshore plate where low carbon equivalent, better weldability and higher toughness are needed at the same strength. Yield strength is 365 MPa in AR versus 385 MPa in TMCP.
Sources
- JIS G3106 Rolled steels for welded structure — JSA (2020)
- ASTM A572/A572M Grade 50 — ASTM (2021)
- GB/T 1591 Q345B / Q355B — SAC (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Heavy plate for welded structures (SM490 series) — Nippon Steel / JFE Steel (2022)
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.