Steel SM520
JIS SM520 · ASTM A572 Gr 60
SM520 is a high-strength weldable JIS structural steel, offered as SM520B and SM520C notch-toughness subgrades and equivalent in strength class to ASTM A572 Grade 60.
Reference datasheet — SM520 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 SM520B condition
SM520 tempers and conditions
SM520 is supplied in 4 conditions, soft to hard. SM520B is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Normalized | Grain-refined heat-treated plate for thick sections needing uniform toughness through thickness. | 390 | 555 | 24 | 165 HB | 10 % IACS |
SM520BDefault As-rolled plate, CVN 27 J @ 0 °C | Standard stocked quality for welded bridge and structural plate at ordinary ambient service. | 395 | 560 | 21 | 170 HB | 10 % IACS |
Improved-toughness quality, CVN 27 J @ -5 °C | Pick when notch toughness at low ambient temperature or thicker welded sections is required. | 400 | 565 | 22 | 172 HB | 10 % IACS |
Thermomechanically controlled processed | Low carbon-equivalent version for thick bridge/penstock plate where preheat-free welding and high toughness matter. | 410 | 570 | 24 | 175 HB | 10 % IACS |
What is SM520?
SM520 is a high-strength weldable JIS structural steel, offered as SM520B and SM520C notch-toughness subgrades and equivalent in strength class to ASTM A572 Grade 60. It delivers 395 MPa yield, 560 MPa tensile, 21 % elongation and about 170 HB in plate, available normalized or TMCP for heavy bridges, penstocks and pressure structures. Weldability is still good (score 82) but the carbon equivalent of roughly 0.40–0.44 requires preheat and hydrogen control on thick plate. No corrosion resistance without coating; SM490A is the easier-to-fabricate step down. SM520 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). SM520 has a yield strength of 395 MPa (57.3 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 63% of steel grades. Elongation at break is 21% and the elastic modulus is 205 GPa (29.7 Msi).
What is SM520 used for?
- bridges
- penstocks
- heavy machinery frames
- welded structures
Advantages
- Conducts heat well — 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
- Readily welded — 82/100, better than 81% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
SM520 properties
Typical room-temperature values for SM520-SM520B; bars are the position among steel grades.
Physical3
SM520 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
SM520 has a yield strength of 395 MPa (57.3 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 63% of steel grades. Elongation at break is 21% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SM520 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
SM520 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 SM520 takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
SM520's machinability is good (55/100, better than 62% of steel grades); weldability very good (82/100); 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. SM520 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SM520
Is SM520 easy to machine?
Machines like medium-carbon structural steel — carbide tooling, ~120–180 m/min turning, expect long stringy chips and moderate tool wear.
Can SM520 be welded?
Readily welded by SMAW/FCAW/SAW with matching 550 MPa-class consumables; CE ≈ 0.40–0.44 so preheat 75–150 °C for plate over ~25 mm and control hydrogen.
Can SM520 be formed, bent or molded?
Cold bends to about 2.5–3 t inside radius across the rolling direction; hot forming 900–1050 °C followed by normalizing for thick sections.
SM520 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≤0.22 for thickness > 50 mm (JIS G 3106) | ≤ 0.2 | 0.17 |
| Si | ≤ 0.55 | 0.35 |
| MnMn typically ≥ 1.0 to reach strength | ≤ 1.6 | 1.4 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.01 |
| Nb+V+Timicroalloying at producer's option for grain refinement | ≤ 0.15 | 0.04 |
| Fe | balance |
What surface finishes work on SM520?
No anodizing; shot-blast to Sa 2½ then epoxy/zinc-rich primer, hot-dip galvanize or metallize for atmospheric and immersion service.
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 SM520 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- A572 Gr 60
How much does SM520 cost?
SM520 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.
SM520 — frequently asked
What is SM520 used for?
SM520 is typically used for bridges, penstocks, heavy machinery frames and welded structures. In short: strongest SM weldable grade; A572 Gr 60 strength class; B/C notch-toughness subgrades.
What is the yield strength of SM520?
SM520 has a typical yield strength of 395 MPa (57.3 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 63% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is SM520 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like medium-carbon structural steel — carbide tooling, ~120–180 m/min turning, expect long stringy chips and moderate tool wear.
Can SM520 be welded?
Yes — weldability is rated very good (82/100). Readily welded by SMAW/FCAW/SAW with matching 550 MPa-class consumables; CE ≈ 0.40–0.44 so preheat 75–150 °C for plate over ~25 mm and control hydrogen.
What surface finishes work on SM520?
No anodizing; shot-blast to Sa 2½ then epoxy/zinc-rich primer, hot-dip galvanize or metallize for atmospheric and immersion service.
Can SM520 be formed, bent or molded?
Cold bends to about 2.5–3 t inside radius across the rolling direction; hot forming 900–1050 °C followed by normalizing for thick sections.
What is the maximum service temperature of SM520?
SM520 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 SM520B and SM520 TMCP?
SM520B is the default condition — standard stocked quality for welded bridge and structural plate at ordinary ambient service. TMCP: low carbon-equivalent version for thick bridge/penstock plate where preheat-free welding and high toughness matter. Yield strength is 395 MPa in SM520B versus 410 MPa in TMCP.
How much does SM520 cost?
SM520 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 3106 — Rolled steels for welded structure — JSA (2020)
- ASTM A572/A572M Grade 60 — HSLA columbium-vanadium structural steel — ASTM (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- Structural / bridge plate grade datasheets (SM490–SM570, TMCP) — Japanese and Chinese plate mills (2023)
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.