Steel SM520B
Grade · default condition
JIS SM520 · ASTM A572 Gr 60
SM520B = as-rolled plate, CVN 27 J @ 0 °C
Standard stocked quality for welded bridge and structural plate at ordinary ambient service.
Values for the SM520B condition
Other SM520 tempers and conditions
SM520 is listed in 4 conditions; see the grade overview at SM520.
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 |
SM520BDefaultThis page 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 SM520B?
SM520B is SM520 in the SM520B grade — standard stocked quality for welded bridge and structural plate at ordinary ambient service. SM520B 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). SM520B 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).
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
SM520B properties
Typical room-temperature values for SM520B; 23 are specific to this condition. Other listed values are SM520 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SM520B 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
SM520B 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
SM520B 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
SM520B 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 SM520B takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
SM520B'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. Confirm any required mill or lot documentation when quoting.
Working with SM520B
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.
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.
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 | — |
SM520B — frequently asked
What is SM520B used for?
SM520B 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 SM520B?
SM520B 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 SM520B 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 SM520B 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 SM520B?
No anodizing; shot-blast to Sa 2½ then epoxy/zinc-rich primer, hot-dip galvanize or metallize for atmospheric and immersion service.
Can SM520B 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 SM520B?
SM520B 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.