Steel 23MnB3
EN 23MnB3
23MnB3 (1.5507) is a manganese-boron cold-heading steel in the EN 10083/10250 alloy steel family, combining about 0.23 % C with manganese and boron for high hardenability at low alloy cost.
Reference datasheet — 23MnB3 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 +QT condition
23MnB3 tempers and conditions
23MnB3 is supplied in 8 conditions, soft to hard. +QT 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 |
|---|---|---|---|---|---|---|
Spheroidize annealed | Pick this for multi-station cold heading/extrusion of bolts and screws — softest, most ductile delivery condition. | 320 | 470 | 26 | 140 HB | — |
Annealed | Sub-critical soft anneal for machining stock and easier straightening. | 340 | 520 | 24 | 155 HB | — |
Hot rolled | Mill-delivered hot-rolled coil, the starting stock before annealing and drawing. | 400 | 600 | 20 | 180 HB | — |
Normalized | Grain refinement after hot forging when parts are not to be hardened. | 400 | 600 | 21 | 10 HRC | 9.5 % IACS |
Cold drawn | Drawn-to-size wire/bar with better surface, straightness and tolerance for automatic heading or turning. | 530 | 620 | 11 | 185 HB | — |
+QT | High-temper condition for class 8.8 bolts where ductility and delayed-fracture safety matter more than peak load. | 720 | 880 | 16 | 26 HRC | — |
+QTDefault Quenched and tempered | Standard service condition for cold-headed fasteners and small shafts after forming — oil/polymer quench plus temper to the required class. | 920 | 1,050 | 13 | 34 HRC | — |
+QT | Highest routine strength level for 23MnB3 fasteners; watch hydrogen embrittlement and keep sections below ~16 mm for through-hardening. | 1,000 | 1,100 | 11 | 36 HRC | — |
What is 23MnB3?
23MnB3 (1.5507) is a manganese-boron cold-heading steel in the EN 10083/10250 alloy steel family, combining about 0.23 % C with manganese and boron for high hardenability at low alloy cost. It is used for quenched-and-tempered fasteners and structural bolts and is supplied as annealed, spheroidized or cold-drawn coil, wire and bar (+A, +AC, +C, +N, +QT). In the default quenched-and-tempered condition it gives about 920 MPa yield, 1050 MPa tensile, 13 % elongation and 320 HB (34 HRC), with a maximum service temperature of 350 °C. Weldability is limited (CE ≈ 0.45–0.55) and the steel has no corrosion resistance; for lower strength with easier welding and forming use 23B2. 23MnB3 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). 23MnB3 has a yield strength of 920 MPa (133 ksi) and a tensile strength of 1,050 MPa (152 ksi) — stronger than 90% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
What is 23MnB3 used for?
- high-strength bolts
- fasteners
- structural pins
Advantages
- High strength — 920 MPa (133 ksi), better than 90% of steel grades
Limitations
- Limited ductility — 13%, worse than 78% of steel grades
23MnB3 properties
Typical room-temperature values for 23MnB3-+QT; bars are the position among steel grades.
Physical3
23MnB3 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
23MnB3 has a yield strength of 920 MPa (133 ksi) and a tensile strength of 1,050 MPa (152 ksi) — stronger than 90% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
23MnB3 is rated for continuous service to 350°C (662 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
23MnB3 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 23MnB3 takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
23MnB3's machinability is fair (42/100, worse than 73% of steel grades); weldability fair (40/100); formability poor (30/100).
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. 23MnB3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 23MnB3
Is 23MnB3 easy to machine?
Machine in +AC or +A condition (≈45–65 % of AISI 1212); in +QT above 32 HRC use coated carbide, rigid setups and reduced feed — the steel is gummy and free-machining additives are absent.
Can 23MnB3 be welded?
Weldable with care (CE ≈ 0.45–0.55): preheat 150–250 °C, low-hydrogen consumables and slow cooling; avoid welding fully hardened fasteners as the HAZ softens and can crack.
Can 23MnB3 be formed, bent or molded?
Designed for multi-station cold heading and cold extrusion in the spheroidized (+AC) phosphate/soap-coated condition; hot forge 1100–1200 °C, then normalize or directly quench and temper.
23MnB3 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 | 0.19 – 0.25 | 0.22 |
| Sioften ≤0.10 for Si-killed cold-heading quality | ≤ 0.3 | 0.15 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Bhardenability booster; must stay in solution | 8×10⁻⁴ – 0.01 | 0 |
| Altotal Al, N-fixing and grain refining | 0.02 – 0.06 | 0.04 |
| Tiadded to protect boron from nitrogen | ≤ 0.05 | 0.03 |
| Crresidual | ≤ 0.3 | 0.1 |
| Niresidual | ≤ 0.3 | 0.08 |
| Curesidual | ≤ 0.25 | 0.1 |
| Nkept low so boron stays effective | ≤ 0.01 | 0.01 |
| Fe | balance |
What surface finishes work on 23MnB3?
Not anodizable — protect with zinc or zinc-nickel electroplating, zinc-flake (Dacromet/Geomet), hot-dip galvanising or phosphate+oil; bake 190–220 °C after plating on ≥10.9 parts to avoid hydrogen embrittlement.
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 23MnB3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.5507
How much does 23MnB3 cost?
23MnB3 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
23MnB3 — frequently asked
What is 23MnB3 used for?
23MnB3 is typically used for high-strength bolts, fasteners and structural pins. In short: high-hardenability bolt steel; class 10.9 at low alloy cost; cold-heading grade.
What is the yield strength of 23MnB3?
23MnB3 has a typical yield strength of 920 MPa (133 ksi) and a tensile strength of 1,050 MPa (152 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 23MnB3 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine in +AC or +A condition (≈45–65 % of AISI 1212); in +QT above 32 HRC use coated carbide, rigid setups and reduced feed — the steel is gummy and free-machining additives are absent.
Can 23MnB3 be welded?
With care — weldability is rated fair (40/100). Weldable with care (CE ≈ 0.45–0.55): preheat 150–250 °C, low-hydrogen consumables and slow cooling; avoid welding fully hardened fasteners as the HAZ softens and can crack.
What surface finishes work on 23MnB3?
Not anodizable — protect with zinc or zinc-nickel electroplating, zinc-flake (Dacromet/Geomet), hot-dip galvanising or phosphate+oil; bake 190–220 °C after plating on ≥10.9 parts to avoid hydrogen embrittlement.
Can 23MnB3 be formed, bent or molded?
Designed for multi-station cold heading and cold extrusion in the spheroidized (+AC) phosphate/soap-coated condition; hot forge 1100–1200 °C, then normalize or directly quench and temper.
What is the maximum service temperature of 23MnB3?
23MnB3 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 23MnB3 cost?
23MnB3 is a budget-cost steel ($), 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 10083-3: Steels for quenching and tempering — Alloy steels — CEN (2019)
- ISO 898-1: Mechanical properties of fasteners made of carbon steel and alloy steel — Bolts, screws and studs — ISO (2013)
- GB/T 6478 (ML23MnB) — SAC (2015)
- 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)
- Cold heading quality boron steel wire rod datasheets (23MnB3 / 1.5507) — European & Asian 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.