Steel 20MnNb6
EN 20MnNb6
20MnNb6 (1.0471) is a niobium-microalloyed fine-grain low-carbon manganese steel classified as non-alloy under EN 10028-3, supplied as plate in +N, +NT, +QT, +N+SR, +AR and +A conditions.
Reference datasheet — 20MnNb6 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 +N condition
20MnNb6 tempers and conditions
20MnNb6 is supplied in 6 conditions, soft to hard. +N is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Use when maximum machinability or deep cold forming is needed before a final normalizing treatment. | 300 | 470 | 30 | 135 HB | 10 % IACS |
Normalized then stress relieved / simulated PWHT | Ordered when the vessel will see post-weld heat treatment; properties are certified after simulated PWHT soak. | 360 | 515 | 26 | 148 HB | 10 % IACS |
Hot rolled | Lowest-cost bar stock for non-critical or subsequently heat-treated parts; toughness scatter is higher than normalized. | 365 | 550 | 23 | 160 HB | 10 % IACS |
Normalized and tempered | Chosen for heavy forgings where a tempering step stabilizes properties and lowers residual stress after normalizing. | 370 | 520 | 26 | 150 HB | 10 % IACS |
+NDefault Normalized | Standard delivery condition for pressure-vessel plate, forgings and bars; best balance of 355 MPa yield, toughness and weldability. | 385 | 540 | 25 | 155 HB | — |
Quenched and tempered | Pick for thick-section forgings or bolting-type parts needing higher yield and uniform through-thickness toughness. | 460 | 590 | 22 | 180 HB | — |
What is 20MnNb6?
20MnNb6 (1.0471) is a niobium-microalloyed fine-grain low-carbon manganese steel classified as non-alloy under EN 10028-3, supplied as plate in +N, +NT, +QT, +N+SR, +AR and +A conditions. Nb grain refinement raises yield to 385 MPa and tensile to 540 MPa while keeping the carbon equivalent low, so it delivers the highest strength in this pressure vessel family without sacrificing weldability (rating 88). Elongation is 25 %, hardness about 155 HB (82 HRB) and maximum service temperature 400 °C. It has no corrosion resistance; P295GH is the lower-strength, more widely stocked alternative. 20MnNb6 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,490°C (2,714 °F). 20MnNb6 has a yield strength of 385 MPa (55.8 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 65% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
What is 20MnNb6 used for?
- pressure vessel plate
- boiler components
- reactor vessels
- chemical process equipment
Advantages
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- Readily welded — 88/100, 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
- 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
20MnNb6 properties
Typical room-temperature values for 20MnNb6-+N; bars are the position among steel grades.
Physical3
20MnNb6 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,490°C (2,714 °F).
Mechanical16
20MnNb6 has a yield strength of 385 MPa (55.8 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 65% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20MnNb6 is rated for continuous service to 400°C (752 °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
20MnNb6 conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 20MnNb6 takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability8
20MnNb6's machinability is good (60/100, better than 83% of steel grades); weldability excellent (88/100); formability very good (70/100).
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. 20MnNb6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 20MnNb6
Is 20MnNb6 easy to machine?
Machines like a 1020/1524-class C-Mn steel at ~65 % of AISI 1212; use positive-rake carbide, moderate speeds and good chip control since the low-sulphur pressure-vessel chemistry gives stringy chips.
Can 20MnNb6 be welded?
Excellent weldability with low CEV — SAW/SMAW/GMAW with low-hydrogen consumables; preheat 100–150 °C for thick sections, PWHT 550–620 °C where code requires, keep heat input moderate to protect the Nb-refined HAZ toughness.
Can 20MnNb6 be formed, bent or molded?
Cold rolls and presses well in the normalized condition (min bend radius ≈ 1.5–2 t); hot form at 900–1150 °C followed by re-normalizing at 880–920 °C to restore fine grain.
20MnNb6 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 |
|---|---|---|
| Cladle analysis | ≤ 0.22 | 0.19 |
| Si | 0.1 – 0.5 | 0.3 |
| Mn | 1 – 1.6 | 1.35 |
| P | ≤ 0.03 | 0.02 |
| Slower S for through-thickness quality | ≤ 0.02 | 0.01 |
| Nbgrain-refining microalloy | 0.02 – 0.05 | 0.03 |
| Altotal Al, fully killed | ≥ 0.02 | 0.04 |
| Crresidual | ≤ 0.3 | 0.1 |
| Niresidual | ≤ 0.3 | 0.1 |
| Curesidual | ≤ 0.3 | 0.1 |
| Moresidual | ≤ 0.08 | 0.02 |
| Vresidual | ≤ 0.02 | 0.01 |
| Ti | ≤ 0.03 | 0.01 |
| N | ≤ 0.01 | 0.01 |
| Fe | balance |
What surface finishes work on 20MnNb6?
No anodizing — protect by shot-blast plus epoxy paint, metallizing, hot-dip galvanizing or weld-overlay/cladding for wet and chloride 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 20MnNb6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.0471
How much does 20MnNb6 cost?
20MnNb6 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
20MnNb6 — frequently asked
What is 20MnNb6 used for?
20MnNb6 is typically used for pressure vessel plate, boiler components, reactor vessels and chemical process equipment. In short: highest strength in family; nb-refined fine grain; low carbon equivalent plate.
What is the yield strength of 20MnNb6?
20MnNb6 has a typical yield strength of 385 MPa (55.8 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 65% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 20MnNb6 easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machines like a 1020/1524-class C-Mn steel at ~65 % of AISI 1212; use positive-rake carbide, moderate speeds and good chip control since the low-sulphur pressure-vessel chemistry gives stringy chips.
Can 20MnNb6 be welded?
Yes — weldability is rated excellent (88/100). Excellent weldability with low CEV — SAW/SMAW/GMAW with low-hydrogen consumables; preheat 100–150 °C for thick sections, PWHT 550–620 °C where code requires, keep heat input moderate to protect the Nb-refined HAZ toughness.
What surface finishes work on 20MnNb6?
No anodizing — protect by shot-blast plus epoxy paint, metallizing, hot-dip galvanizing or weld-overlay/cladding for wet and chloride service.
Can 20MnNb6 be formed, bent or molded?
Cold rolls and presses well in the normalized condition (min bend radius ≈ 1.5–2 t); hot form at 900–1150 °C followed by re-normalizing at 880–920 °C to restore fine grain.
What is the maximum service temperature of 20MnNb6?
20MnNb6 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 20MnNb6 cost?
20MnNb6 is a budget-cost steel ($), 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
- EN 10222-2 — Steel forgings for pressure purposes: ferritic and martensitic steels with specified elevated temperature properties — CEN (2021)
- EN 10273 — Hot rolled weldable steel bars for pressure purposes with specified elevated temperature properties — CEN (2016)
- EN 10028-2/-3 — Flat products made of steels for pressure purposes — CEN (2017)
- EN 10027-2 / CR 10260 material number 1.0471 — CEN (2015)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook, 31st ed. (machinability ratings) — Industrial Press (2020)
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.