Steel 28B2
EN 28B2
28B2 (1.5510) is a medium-carbon boron steel in the EN 10083/10250 alloy steel family, carrying more carbon than 23B2 for higher tempered strength from the same low-alloy chemistry.
Reference datasheet — 28B2 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
28B2 tempers and conditions
28B2 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 — choose when severe multi-station cold heading or thread rolling is required before quenching. | 330 | 510 | 26 | 150 HB | — |
Hot rolled | Cheapest supply form for hot-forged bolts, pins and parts that will be re-annealed or directly quenched. | 400 | 620 | 20 | 185 HB | — |
+AC+CDefault Spheroidize annealed then cold drawn | The standard cold-heading wire condition: good size/finish with retained upsettability for bolt and pin blanks. | 520 | 620 | 12 | 190 HB | — |
Untreated then cold drawn | Pick for straight, close-tolerance bright bar/wire where only light upsetting or machining follows. | 600 | 700 | 9 | 210 HB | — |
Specified hardenability, quenched and tempered condition | Final in-service condition of the part: oil-quenched ~860 °C and tempered 430–550 °C for property class 8.8–10.9 fasteners. | 850 | 1,000 | 13 | 31 HRC | — |
What is 28B2?
28B2 (1.5510) is a medium-carbon boron steel in the EN 10083/10250 alloy steel family, carrying more carbon than 23B2 for higher tempered strength from the same low-alloy chemistry. It is used for quenched-and-tempered fasteners, high-strength bolts and pins, and is supplied as annealed, spheroidized and cold-drawn wire and bar (+U, +AC, +AC+C, +H). Default values are about 520 MPa yield, 620 MPa tensile, 12 % elongation and 190 HB, with a maximum service temperature of 350 °C. Weldability (CE ≈ 0.45) and cold formability are lower than 23B2, and the steel has no corrosion resistance; drop to 23B2 for severe upsets or welded parts. 28B2 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). 28B2 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 67% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
What is 28B2 used for?
- high-strength bolts
- fasteners
- pins
Advantages
- Forms and bends easily — 65/100, better than 81% of steel grades
Limitations
- Limited ductility — 12%, worse than 84% of steel grades
28B2 properties
Typical room-temperature values for 28B2-+AC+C; bars are the position among steel grades.
Physical3
28B2 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).
Mechanical13
28B2 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 67% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
28B2 is rated for continuous service to 350°C (662 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
28B2 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 28B2 takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
28B2's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (45/100); formability good (65/100).
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. 28B2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 28B2
Is 28B2 easy to machine?
Machines like 1030 in the +AC/+C states (~60 % of 1212); after Q&T above 300 HB use coated carbide, rigid setups and expect shorter tool life — no free-machining sulphur available.
Can 28B2 be welded?
Weldable with preheat 150–250 °C and low-hydrogen consumables (CE ≈ 0.45), but boron narrows the HAZ toughness window; avoid welding finished Q&T fasteners.
Can 28B2 be formed, bent or molded?
Designed for cold heading and thread rolling in the +AC or +AC+C state; keep upset ratios moderate, use phosphate + soap or polymer lubricant, and hot forge 1050–1200 °C.
28B2 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 |
|---|---|---|
| Cgives the Q&T strength level | 0.25 – 0.32 | 0.28 |
| Si | ≤ 0.3 | 0.15 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | 0.01 |
| Slow S for cold heading | ≤ 0.03 | 0.01 |
| Bhardenability booster; must be in solid solution | 8×10⁻⁴ – 0.01 | 0 |
| Crresidual | ≤ 0.3 | 0.1 |
| Niresidual | ≤ 0.3 | 0.08 |
| Curesidual | ≤ 0.25 | 0.1 |
| Tiadded to fix N so B stays effective | ≤ 0.05 | 0.03 |
| Algrain refining / N control | 0.02 – 0.06 | 0.04 |
| Nmust be tied up by Ti/Al | ≤ 0.01 | 0.01 |
| Fe | balance |
What surface finishes work on 28B2?
Bare steel must be protected: zinc or Zn-Ni electroplate with immediate 200 °C bake to avoid hydrogen embrittlement above 1000 MPa, or use Zn-flake/mechanical galvanizing and phosphate+oil for indoor parts.
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 28B2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.5510
How much does 28B2 cost?
28B2 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
28B2 — frequently asked
What is 28B2 used for?
28B2 is typically used for high-strength bolts, fasteners and pins. In short: higher strength than 23B2; cold-headable medium-carbon boron steel.
What is the yield strength of 28B2?
28B2 has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 67% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is 28B2 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machines like 1030 in the +AC/+C states (~60 % of 1212); after Q&T above 300 HB use coated carbide, rigid setups and expect shorter tool life — no free-machining sulphur available.
Can 28B2 be welded?
With care — weldability is rated fair (45/100). Weldable with preheat 150–250 °C and low-hydrogen consumables (CE ≈ 0.45), but boron narrows the HAZ toughness window; avoid welding finished Q&T fasteners.
What surface finishes work on 28B2?
Bare steel must be protected: zinc or Zn-Ni electroplate with immediate 200 °C bake to avoid hydrogen embrittlement above 1000 MPa, or use Zn-flake/mechanical galvanizing and phosphate+oil for indoor parts.
Can 28B2 be formed, bent or molded?
Designed for cold heading and thread rolling in the +AC or +AC+C state; keep upset ratios moderate, use phosphate + soap or polymer lubricant, and hot forge 1050–1200 °C.
What is the maximum service temperature of 28B2?
28B2 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 28B2 cost?
28B2 is a budget-cost steel ($), 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)
- EN 10083-3 — Steels for quenching and tempering: alloy steels — CEN (2006)
- 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. 4 — Heat Treating (boron steels, hardenability) — ASM International (1991)
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.