Steel 20MnB4
EN 20MnB4
20MnB4 (1.5525) is a low-alloy manganese-boron cold-heading steel in the EN 10263 family, supplied as untreated, annealed or drawn wire and rod (+U, +AC, +AC+C, +U+C, +TH, +H).
Reference datasheet — 20MnB4 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 +AC+C condition
20MnB4 tempers and conditions
20MnB4 is supplied in 6 conditions, soft to hard. +AC+C 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 |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for the softest, most ductile state before severe multi-station cold heading or cold extrusion of complex parts. | 310 | 460 | 26 | 135 HB | — |
Treated to ferrite-pearlite structure | Isothermally treated for uniform ferrite-pearlite and consistent drawing behaviour; a middle ground between +U and +AC. | 370 | 540 | 22 | 155 HB | 8.8 % IACS |
Hot rolled | Mill hot-rolled condition; the cheapest input for further annealing, drawing or hot forging, not for direct severe cold heading. | 390 | 580 | 20 | 170 HB | — |
+AC+CDefault Spheroidize annealed then cold drawn | The standard cold-heading wire delivery condition: annealed for ductility, drawn to size and phosphate/soap coated for die life. | 450 | 550 | 13 | 160 HB | — |
Cold drawn from untreated hot-rolled stock | Drawn without prior spheroidizing — higher strength and better straightness/tolerance, but limited upset ratio; suits light heading and machined parts. | 580 | 660 | 9 | 195 HB | — |
Supplied with specified hardenability, quenched and tempered after… | Pick when the finished fastener must be oil/water quenched and tempered to 800–1000 MPa; the guaranteed Jominy band ensures reproducible core hardness. | 750 | 900 | 13 | 28 HRC | — |
What is 20MnB4?
20MnB4 (1.5525) is a low-alloy manganese-boron cold-heading steel in the EN 10263 family, supplied as untreated, annealed or drawn wire and rod (+U, +AC, +AC+C, +U+C, +TH, +H). It is chosen for medium-strength bolts, screws and cold-formed fasteners where boron gives adequate hardenability without Cr-Mo alloying; the annealed condition gives 450 MPa yield, 550 MPa tensile, 13 % elongation and 160 HB (84 HRB) with a formability score of 85. It has no corrosion resistance bare and quenched-and-tempered parts are crack-sensitive when welded; 27MnCrB5-2 is the step up for class 10.9 and 12.9. 20MnB4 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). 20MnB4 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 52% of steel grades. Elongation at break is 13% and the elastic modulus is 207 GPa (30 Msi).
What is 20MnB4 used for?
- bolts
- screws
- cold-formed fasteners
Advantages
- Forms and bends easily — 85/100, better than 96% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
Limitations
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
20MnB4 properties
Typical room-temperature values for 20MnB4-+AC+C; bars are the position among steel grades.
Physical3
20MnB4 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
20MnB4 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 52% of steel grades. Elongation at break is 13% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
20MnB4 is rated for continuous service to 250°C (482 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
20MnB4 conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 20MnB4 takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
20MnB4's machinability is good (55/100, better than 62% of steel grades); weldability good (55/100); formability excellent (85/100).
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. 20MnB4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 20MnB4
Is 20MnB4 easy to machine?
Machines like 1020/1518 in the annealed state (~60–65 % of 1212); use sharp positive tooling and chip breakers because low-sulphur cold-heading steel produces stringy chips.
Can 20MnB4 be welded?
Weldable with CE_IIW ≈ 0.45 using low-hydrogen consumables; preheat 100–150 °C above ~16 mm and avoid welding on quenched-and-tempered fasteners as boron martensite is crack-sensitive.
Can 20MnB4 be formed, bent or molded?
Excellent cold heading, extrusion and thread rolling in +AC/+AC+C with phosphate-soap or polymer lubricant; upset ratios above ~2.5:1 need the spheroidized condition.
20MnB4 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 | 0.18 – 0.23 | 0.2 |
| Simax per EN 10263-4 | ≤ 0.3 | 0.15 |
| Mn | 0.9 – 1.2 | 1.05 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Bboron for hardenability; effective B requires Ti/Al nitrogen fixation | 8×10⁻⁴ – 0.01 | 0 |
| Altotal Al, for nitrogen binding and grain refinement | ≥ 0.02 | 0.04 |
| Tioptional, common producer practice to protect boron | ≤ 0.05 | 0.03 |
| Fe | balance |
What surface finishes work on 20MnB4?
No corrosion resistance bare — zinc electroplate, zinc-nickel, zinc flake (Dacromet/Geomet) or phosphate-and-oil; bake at 190–220 °C within 4 h after plating parts harder than ~32 HRC to relieve hydrogen.
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 20MnB4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.5525
How much does 20MnB4 cost?
20MnB4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
20MnB4 — frequently asked
What is 20MnB4 used for?
20MnB4 is typically used for bolts, screws and cold-formed fasteners. In short: most formable boron steel; weldable cold-heading grade; economical medium-strength fasteners.
What is the yield strength of 20MnB4?
20MnB4 has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 52% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 20MnB4 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like 1020/1518 in the annealed state (~60–65 % of 1212); use sharp positive tooling and chip breakers because low-sulphur cold-heading steel produces stringy chips.
Can 20MnB4 be welded?
Yes — weldability is rated good (55/100). Weldable with CE_IIW ≈ 0.45 using low-hydrogen consumables; preheat 100–150 °C above ~16 mm and avoid welding on quenched-and-tempered fasteners as boron martensite is crack-sensitive.
What surface finishes work on 20MnB4?
No corrosion resistance bare — zinc electroplate, zinc-nickel, zinc flake (Dacromet/Geomet) or phosphate-and-oil; bake at 190–220 °C within 4 h after plating parts harder than ~32 HRC to relieve hydrogen.
Can 20MnB4 be formed, bent or molded?
Excellent cold heading, extrusion and thread rolling in +AC/+AC+C with phosphate-soap or polymer lubricant; upset ratios above ~2.5:1 need the spheroidized condition.
What is the maximum service temperature of 20MnB4?
20MnB4 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 20MnB4 cost?
20MnB4 is a budget-cost steel ($), 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 10263-4: Steel rod, bars and wire for cold heading and cold extrusion — Part 4: Steels for quenching and tempering — CEN (2018)
- EN 10263-1/-2: Cold heading steels — general technical delivery conditions and delivery conditions for untreated/soft-annealed steels — CEN (2018)
- ISO 898-1: Mechanical properties of fasteners made of carbon steel and alloy steel — ISO (2013)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 4A: Steel Heat Treating Fundamentals and Processes (boron hardenability) — ASM International (2013)
- Cold heading quality boron steel wire rod datasheets (20MnB4 / 1.5525) — European & Chinese wire rod producers (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.