Steel SM490
JIS SM490
SM490 is a Japanese (JIS G 3106) hot-rolled carbon-manganese steel for welded structures, supplied as plate, strip, sections and bars with a 490–610 MPa tensile class and ≥325 MPa yield.
Values for the HR condition
SM490 tempers and conditions
SM490 is supplied in 8 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
No specified Charpy requirement | Lowest-cost sub-grade for ordinary indoor or ambient-temperature welded structures. | 360 | 530 | 22 | 158 HB | 8.6 % IACS |
HRDefault Hot rolled | Default stock condition for structural plate, strip and sections; use for welded frames, bridges and machine bases. | 365 | 530 | 23 | 160 HB | 8.6 % IACS |
Charpy ≥27 J at 0 °C | Standard choice for bridges and outdoor frames with moderate notch-toughness demand. | 365 | 530 | 23 | 160 HB | 8.6 % IACS |
Normalized | Pick for thick plate or low-temperature/high-toughness duty where uniform fine grain and reliable Charpy values are required. | 370 | 540 | 25 | 155 HB | 8.6 % IACS |
Charpy ≥47 J at 0 °C, lower carbon | Use for thick, highly restrained or fatigue-loaded welded joints demanding high toughness. | 370 | 535 | 24 | 162 HB | 8.6 % IACS |
Higher yield class (≥365 MPa), no Charpy requirement | Pick when design is yield-governed and weight saving matters, in non-critical toughness service. | 400 | 540 | 20 | 170 HB | 8.5 % IACS |
Higher yield class (≥365 MPa) with Charpy ≥27 J at 0 °C | High-yield sub-grade with guaranteed toughness for bridge girders and heavy welded sections. | 405 | 545 | 21 | 172 HB | 8.5 % IACS |
Cold rolled | Choose when tight thickness tolerance, clean surface and higher yield are wanted; ductility and bend radius suffer. | 480 | 600 | 14 | 185 HB | 8.6 % IACS |
Supply forms, finishes and certifications
Ways SM490 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Galvanized | Hot-dip zinc coated | Coating |
What is SM490?
SM490 is a Japanese (JIS G 3106) hot-rolled carbon-manganese steel for welded structures, supplied as plate, strip, sections and bars with a 490–610 MPa tensile class and ≥325 MPa yield. It is chosen for bridges, building frames, cranes and pressure-bearing structures where mild steel (SM400) is too weak but full alloying is unnecessary; sub-grades A/B/C add progressively stricter Charpy requirements and YA/YB raise the yield to 365 MPa. Limits are ordinary atmospheric corrosion resistance (needs paint or galvanizing), modest low-temperature toughness for grade A, and loss of strength above roughly 350 °C. SM490 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). SM490 has a yield strength of 365 MPa (52.9 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 71% of steel grades. Elongation at break is 23% and the elastic modulus is 206 GPa (29.9 Msi).
What is SM490 used for?
- Welded bridge girders
- Industrial building frames
- Crane and gantry structures
- Pressure-bearing structural frames
- Heavy machine bases and weldments
- Galvanized structural sections
Advantages
- Readily welded — 85/100, better than 83% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
SM490 properties
Typical room-temperature values for SM490-HR; bars are the position among steel grades.
Physical3
SM490 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
SM490 has a yield strength of 365 MPa (52.9 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 71% of steel grades. Elongation at break is 23% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
SM490 is rated for continuous service to 350°C (662 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
SM490 conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of SM490 takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
SM490's machinability is good (55/100, better than 62% of steel grades); weldability excellent (85/100); formability good (60/100).
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. SM490 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SM490
Is SM490 easy to machine?
Machines like ordinary C-Mn structural steel (~55–60 % of 1212); use coated carbide, moderate speeds and generous coolant, expect gummy chips and mill-scale abrasion on the first pass.
Can SM490 be welded?
Designed for welding — SMAW/GMAW/SAW with E70xx-class consumables; preheat 50–150 °C for thick or restrained joints and keep hydrogen low to avoid HAZ cracking.
Can SM490 be formed, bent or molded?
Good hot forming and press braking; keep cold bend radius ≥2t (≥3t for thick plate) and bend transverse to the rolling direction.
Manufacturability
The process limits FabDigit applies to SM490. Every SM490 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better55 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Excellent60 / 100 |
|---|---|
| Weldability | Excellent85 / 100 |
| Bendable | Yes |
SM490 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 (SM490A/YA/YB); ≤0.18 for SM490C | ≤ 0.2 | 0.16 |
| Si | ≤ 0.55 | 0.3 |
| MnSM490C: 1.60 max, deoxidized/killed practice | ≤ 1.6 | 1.3 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.01 |
| Febalance, plus residual Cu/Ni/Cr and micro-alloy additions at mill option | balance |
What surface finishes work on SM490?
Blast off mill scale then zinc-rich primer, paint or hot-dip galvanize; not anodizable and bare surfaces rust quickly outdoors.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel SM490 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- JIS
- G 3106 SM490
How much does SM490 cost?
SM490 is a budget-cost steel ($), cheaper than about 99% 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.
SM490 — frequently asked
What is SM490 used for?
SM490 is typically used for welded bridge girders, industrial building frames, crane and gantry structures, pressure-bearing structural frames, heavy machine bases and weldments and galvanized structural sections. In short: japanese structural plate.
What is the yield strength of SM490?
SM490 has a typical yield strength of 365 MPa (52.9 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 71% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is SM490 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like ordinary C-Mn structural steel (~55–60 % of 1212); use coated carbide, moderate speeds and generous coolant, expect gummy chips and mill-scale abrasion on the first pass.
Can SM490 be welded?
Yes — weldability is rated excellent (85/100). Designed for welding — SMAW/GMAW/SAW with E70xx-class consumables; preheat 50–150 °C for thick or restrained joints and keep hydrogen low to avoid HAZ cracking.
What surface finishes work on SM490?
Blast off mill scale then zinc-rich primer, paint or hot-dip galvanize; not anodizable and bare surfaces rust quickly outdoors.
Can SM490 be formed, bent or molded?
Good hot forming and press braking; keep cold bend radius ≥2t (≥3t for thick plate) and bend transverse to the rolling direction.
What is the maximum service temperature of SM490?
SM490 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 SM490-HR and SM490-CR?
HR is the default condition — default stock condition for structural plate, strip and sections; use for welded frames, bridges and machine bases. CR: choose when tight thickness tolerance, clean surface and higher yield are wanted; ductility and bend radius suffer. Yield strength is 365 MPa in HR versus 480 MPa in CR.
How much does SM490 cost?
SM490 is a budget-cost steel ($), cheaper than about 99% 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.
Can FabDigit make parts in SM490?
Yes — SM490 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- JIS G 3106 Rolled steels for welded structure — JISC (2020)
- GB/T 1591 Q345B (equivalent low-alloy structural steel) — SAC (2018)
- ASM Handbook Vol.1 — Properties of Carbon and Low-Alloy Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- Structural plate product guide (SM490A/B/C) — Nippon Steel / JFE Steel (2022)
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.