Steel 27MnB4
EN 27MnB4
27MnB4 (1.5536) is a medium-carbon boron-manganese steel in the EN 10083 alloy steel family, sitting between 23MnB4 and 30MnB4 in carbon and hardenability.
Reference datasheet — 27MnB4 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
27MnB4 tempers and conditions
27MnB4 is supplied in 7 conditions, soft to hard. +AC+C is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Pick for the softest, most ductile state before severe multi-station cold heading or deep upsetting. | 380 | 555 | 22 | 160 HB | 45 W/m·K |
Treated to hardness | Chosen when clean shearing/blanking and consistent slug hardness matter more than maximum ductility. | 420 | 620 | 18 | 11 HRC | 8.8 % IACS |
Hot rolled | Mill as-rolled coil bought for re-processing (own annealing/drawing) or for hot-forged parts. | 430 | 700 | 16 | 205 HB | — |
+AC+CDefault Spheroidize annealed and cold drawn | Standard cold-heading quality (CHQ) wire/bar: sized, straight, lubricant-carrier coated and ready for the header. | 560 | 660 | 11 | 200 HB | — |
quenched and tempered to property class 8.8 (~26–32 HRC) | General-purpose hardened fastener condition with good toughness and no bake-embrittlement worry. | 700 | 880 | 15 | 29 HRC | — |
quenched and tempered to property class 10.9 (~32–39 HRC) | The reason this grade exists: high-strength structural and automotive bolts through-hardened in sizes up to roughly M14–M16. | 990 | 1,100 | 12 | 35 HRC | 43 W/m·K |
Hardened | As-quenched / low-temper condition used when maximum hardness and full through-hardening of the fastener core are required; boron guarantees the Jominy band. | 1,300 | 1,650 | 7 | 48 HRC | 42 W/m·K |
What is 27MnB4?
27MnB4 (1.5536) is a medium-carbon boron-manganese steel in the EN 10083 alloy steel family, sitting between 23MnB4 and 30MnB4 in carbon and hardenability. It is used for cold-headed fasteners that must through-harden to property class 8.8 or 10.9, and is supplied as cold heading quality wire, coil and bar in +U, +AC, +AC+C, +TH and +H conditions. In the default condition it gives 560 MPa yield, 660 MPa tensile, 11 % elongation and 200 HB (93 HRB) with a 350 °C service limit. Weldability is limited and there is no corrosion resistance; use 23MnB4 where headability matters more than strength. 27MnB4 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). 27MnB4 has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 73% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi).
What is 27MnB4 used for?
- Property class 8.8 and 10.9 bolts
- Cold-headed hex and flange screws
- Wheel and suspension fasteners
- Thread-rolled studs
- Nuts and cold-extruded fastener blanks
- Small shafts and pins
Advantages
- Forms and bends easily — 70/100, better than 86% of steel grades
Limitations
- Limited ductility — 11%, worse than 89% of steel grades
27MnB4 properties
Typical room-temperature values for 27MnB4-+AC+C; bars are the position among steel grades.
Physical3
27MnB4 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).
Mechanical15
27MnB4 has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 73% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
27MnB4 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 µm/m·K (6.67 µin/in·°F).
Electrical3
27MnB4 conducts electricity at 8.5 % IACS, better than 63% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 27MnB4 takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
27MnB4's machinability is fair (48/100, worse than 57% of steel grades); weldability fair (40/100); 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. 27MnB4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 27MnB4
Is 27MnB4 easy to machine?
Machine in the +AC or +AC+C state (about 60–65 % of AISI 1212); after Q&T to 10.9 use coated carbide with rigid setups, and expect poor chip breaking due to the low sulphur of CHQ heats.
Can 27MnB4 be welded?
Weldable only with care — CE(IIW) ≈ 0.5–0.6, so preheat 150–250 °C, low-hydrogen consumables and post-weld tempering; never weld finished class 10.9 parts.
Can 27MnB4 be formed, bent or molded?
Excellent multi-blow cold heading and thread rolling in +AC/+AC+C with phosphate + soap or polymer lubricant; anneal between severe upsets and avoid work-hardening before quench.
27MnB4 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 | 0.24 – 0.3 | 0.27 |
| Simax for cold-heading quality | ≤ 0.3 | 0.15 |
| Mn | 0.9 – 1.2 | 1.05 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Beffective (soluble) boron controls hardenability | 8×10⁻⁴ – 0.01 | 0 |
| Altotal Al, for nitrogen fixing / grain size | ≥ 0.02 | 0.03 |
| Tioptional, added to tie up free nitrogen and protect the boron effect | ≤ 0.05 | 0.03 |
| Crresidual | ≤ 0.3 | 0.1 |
| Niresidual | ≤ 0.3 | 0.08 |
| Curesidual | ≤ 0.25 | 0.1 |
| Fe | balance |
What surface finishes work on 27MnB4?
Austenitize 860–890 °C, oil or polymer quench, temper 400–500 °C for 10.9; finish with zinc, zinc-nickel or zinc-flake — electroplated parts above 1000 MPa must be baked within 4 h per ISO 4042.
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 27MnB4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.5536
How much does 27MnB4 cost?
27MnB4 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.
27MnB4 — frequently asked
What is 27MnB4 used for?
27MnB4 is typically used for property class 8.8 and 10.9 bolts, cold-headed hex and flange screws, wheel and suspension fasteners, thread-rolled studs, nuts and cold-extruded fastener blanks and small shafts and pins. In short: balanced heading and hardenability; 8.8/10.9 bolt steel; through-hardening boron grade.
What is the yield strength of 27MnB4?
27MnB4 has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 73% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 27MnB4 easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Machine in the +AC or +AC+C state (about 60–65 % of AISI 1212); after Q&T to 10.9 use coated carbide with rigid setups, and expect poor chip breaking due to the low sulphur of CHQ heats.
Can 27MnB4 be welded?
With care — weldability is rated fair (40/100). Weldable only with care — CE(IIW) ≈ 0.5–0.6, so preheat 150–250 °C, low-hydrogen consumables and post-weld tempering; never weld finished class 10.9 parts.
What surface finishes work on 27MnB4?
Austenitize 860–890 °C, oil or polymer quench, temper 400–500 °C for 10.9; finish with zinc, zinc-nickel or zinc-flake — electroplated parts above 1000 MPa must be baked within 4 h per ISO 4042.
Can 27MnB4 be formed, bent or molded?
Excellent multi-blow cold heading and thread rolling in +AC/+AC+C with phosphate + soap or polymer lubricant; anneal between severe upsets and avoid work-hardening before quench.
What is the maximum service temperature of 27MnB4?
27MnB4 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 27MnB4 cost?
27MnB4 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 / EN 10084 (related boron steel practice) — CEN (2018)
- ISO 898-1: Mechanical properties of fasteners — bolts, screws and studs — 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 (boron hardenability) — ASM International (2013)
- CHQ boron steel wire rod datasheets (27MnB4 / 1.5536) — European and 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.