Steel 18MnB4
EN 18MnB4
18MnB4 (1.5521) is a boron-manganese fastener steel closely related to 17MnB4, with chemistry adjusted for consistent through-hardening of cold-headed bolts.
Reference datasheet — 18MnB4 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
18MnB4 tempers and conditions
18MnB4 is supplied in 5 conditions, soft to hard. +AC+C is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Softest condition with globular carbides — pick for the most severe cold heading, extrusion or thread rolling. | 310 | 470 | 26 | 140 HB | — |
Hot rolled | Cheapest mill condition — pick for further in-house annealing/drawing or for hot-formed parts. | 380 | 570 | 20 | 168 HB | — |
+AC+CDefault Spheroidize annealed and cold drawn | The standard fastener-wire supply condition: soft ductile core with sized, clean drawn surface for high-speed cold heading. | 470 | 560 | 13 | 172 HB | — |
Untreated (hot rolled) and cold drawn | Drawn straight from hot-rolled rod without annealing — pick for moderate upsetting, machined parts and cost-driven bar stock. | 560 | 640 | 9 | 195 HB | — |
Hardened and tempered | Final in-service condition of cold-headed parts: austenitize ~880–920 °C, quench, temper 400–500 °C for 8.8 or 340–420 °C for 10.9. | 940 | 1,050 | 12 | 33 HRC | — |
What is 18MnB4?
18MnB4 (1.5521) is a boron-manganese fastener steel closely related to 17MnB4, with chemistry adjusted for consistent through-hardening of cold-headed bolts. It is stocked as cold-heading wire and drawn bar; the annealed/drawn condition on file gives about 470 MPa yield, 560 MPa tensile, 13 % elongation and 172 HB (88 HRB), with formability rated 82 and machinability 62. Rated strength only develops in the +H condition, weldability is limited (score 55) because boron raises HAZ hardenability, and the steel needs a coating for any corrosive service. Choose 17MnB4 for easier welding or 22MnB4 for higher strength classes. 18MnB4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). 18MnB4 has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 57% of steel grades. Elongation at break is 13% and the elastic modulus is 207 GPa (30 Msi).
What is 18MnB4 used for?
- fasteners
- bolts
- cold heading wire
Advantages
- Forms and bends easily — 82/100, better than 94% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Easy to machine — 62/100, better than 89% of steel grades
Limitations
- Limited ductility — 13%, worse than 78% of steel grades
18MnB4 properties
Typical room-temperature values for 18MnB4-+AC+C; bars are the position among steel grades.
Physical3
18MnB4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical14
18MnB4 has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 57% of steel grades. Elongation at break is 13% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
18MnB4 is rated for continuous service to 350°C (662 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.1 µm/m·K (6.72 µin/in·°F).
Electrical3
18MnB4 conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 18MnB4 takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
18MnB4's machinability is good (62/100, better than 89% of steel grades); weldability good (55/100); formability very good (82/100).
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. 18MnB4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 18MnB4
Is 18MnB4 easy to machine?
Machines like 1018/15B21 in the annealed or drawn state (≈65 % of AISI 1212); after +H hardening use coated carbide, rigid setups and expect noticeably lower tool life.
Can 18MnB4 be welded?
Weldable by resistance and MAG but boron sharply raises HAZ hardenability — limit heat input, preheat 100–150 °C on thicker sections and avoid welding fully hardened high-class fasteners.
Can 18MnB4 be formed, bent or molded?
Designed for cold heading, extrusion and thread rolling in +AC or +AC+C; phosphate/lubricate the wire, and heat treat after forming since only the +H condition develops rated strength.
18MnB4 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 | 0.15 – 0.21 | 0.18 |
| Sioften ≤0.10 for Si-killed cold-heading wire | ≤ 0.3 | 0.15 |
| Mn | 0.7 – 1.1 | 0.9 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Bhardenability agent; must be protected from N by Ti/Al | 8×10⁻⁴ – 0.01 | 0 |
| TiN-fixing addition, optional per melting practice | 0.02 – 0.05 | 0.04 |
| Altotal Al, deoxidation/N control | 0.02 – 0.06 | 0.04 |
| Crresidual | ≤ 0.3 | 0.1 |
| Niresidual | ≤ 0.3 | 0.08 |
| Curesidual | ≤ 0.25 | 0.1 |
| Fe | balance |
What surface finishes work on 18MnB4?
No anodizing; use zinc or zinc-nickel electroplating, zinc-flake coating or hot-dip galvanizing, plus hydrogen-relief bake within 4 h for parts ≥1000 MPa.
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 18MnB4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.5521
How much does 18MnB4 cost?
18MnB4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
18MnB4 — frequently asked
What is 18MnB4 used for?
18MnB4 is typically used for fasteners, bolts and cold heading wire. In short: consistent through-hardening; cold-heading grade; between 17MnB4 and 22MnB4.
What is the yield strength of 18MnB4?
18MnB4 has a typical yield strength of 470 MPa (68.2 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 57% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is 18MnB4 easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machines like 1018/15B21 in the annealed or drawn state (≈65 % of AISI 1212); after +H hardening use coated carbide, rigid setups and expect noticeably lower tool life.
Can 18MnB4 be welded?
Yes — weldability is rated good (55/100). Weldable by resistance and MAG but boron sharply raises HAZ hardenability — limit heat input, preheat 100–150 °C on thicker sections and avoid welding fully hardened high-class fasteners.
What surface finishes work on 18MnB4?
No anodizing; use zinc or zinc-nickel electroplating, zinc-flake coating or hot-dip galvanizing, plus hydrogen-relief bake within 4 h for parts ≥1000 MPa.
Can 18MnB4 be formed, bent or molded?
Designed for cold heading, extrusion and thread rolling in +AC or +AC+C; phosphate/lubricate the wire, and heat treat after forming since only the +H condition develops rated strength.
What is the maximum service temperature of 18MnB4?
18MnB4 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 18MnB4 cost?
18MnB4 is a budget-cost steel ($), 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: steels for quenching and tempering — CEN (2017)
- 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/16 — Steel Heat Treating and Machining — ASM International (2013)
- Boron cold-heading wire grades (17MnB4/20MnB4 family) data sheets — European wire-rod producers (2022)
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.