Steel 23B2 +U+C (Untreated, cold drawn)
Supply condition
EN 23B2
Drawn-to-size bright bar/wire with better tolerance and surface for light heading, machining or direct hardening.
Values for the +U+C condition
Other 23B2 tempers and conditions
23B2 is listed in 6 conditions; see the grade overview at 23B2.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Softest condition, maximum cold-heading and extrusion capability before final sizing. | 300 | 450 | 25 | 128 HB | — |
Treated to ferrite-pearlite structure | Uniform ferrite-pearlite delivery condition when moderate strength plus reliable machining/heading of thicker sections is wanted. | 340 | 520 | 22 | 152 HB | — |
Hot rolled | Pick when the fastener maker will do its own spheroidizing or when only light upsetting/heading is needed. | 380 | 560 | 22 | 165 HB | — |
+AC+CDefault Spheroidize annealed and cold drawn | Standard stocked cold-heading wire: soft spheroidized structure sized by a light draw, ready for multi-station header feed. | 400 | 500 | 14 | 145 HB | — |
+U+CThis page Untreated, cold drawn | Drawn-to-size bright bar/wire with better tolerance and surface for light heading, machining or direct hardening. | 560 | 650 | 10 | 195 HB | — |
Hardened and tempered | Final in-service condition of the finished part: water/oil quench from ~880 °C and temper 400–540 °C to reach class 8.8 strength. | 700 | 850 | 13 | 26 HRC | — |
What is 23B2 +U+C?
23B2 +U+C is 23B2 supplied in the +U+C condition — drawn-to-size bright bar/wire with better tolerance and surface for light heading, machining or direct hardening. 23B2 +U+C has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 650 MPa (94.3 ksi) — stronger than 73% of steel grades. Elongation at break is 10% and the elastic modulus is 205 GPa (29.7 Msi). 23B2 +U+C has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F). +AC+C is the default condition FabDigit quotes; +U+C is available on request or by drawing note.
Advantages
- Easy to machine — 66/100, better than 95% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
Limitations
- Limited ductility — 10%, worse than 91% of steel grades
23B2 +U+C properties
Typical room-temperature values for 23B2 +U+C; 14 are specific to this condition. Other listed values are 23B2 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
23B2 +U+C has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F).
Mechanical14
23B2 +U+C has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 650 MPa (94.3 ksi) — stronger than 73% of steel grades. Elongation at break is 10% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
23B2 +U+C is rated for continuous service to 350°C (662 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
23B2 +U+C conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 23B2 +U+C takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
23B2 +U+C's machinability is good (66/100, better than 95% of steel grades); weldability very good (70/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 23B2 +U+C
Is 23B2 easy to machine?
Machines like a soft 1020/1023 — gummy in the spheroidized state; use sharp positive-rake tooling, good chip breaking, or machine after Q&T at ~25 HRC.
Can 23B2 be welded?
Weldable (CEV ≈ 0.30–0.35) with SMAW/GMAW, but boron sharply increases HAZ hardenability — preheat 100–150 °C on heavy sections and avoid welding hardened fasteners.
Can 23B2 be formed, bent or molded?
Designed for multi-station cold heading and cold extrusion in +AC or +AC+C; phosphate + soap or polymer lubricant coating, and inter-pass spheroidizing for very severe upsets.
What surface finishes work on 23B2?
No inherent corrosion resistance: zinc or zinc-nickel electroplate (with bake for hydrogen relief), zinc-flake dip-spin, or phosphate-and-oil; not anodizable.
23B2 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 | 0.2 – 0.25 | 0.23 |
| Si | ≤ 0.3 | 0.15 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Bboron for hardenability | 8×10⁻⁴ – 0.01 | 0 |
| Altotal Al (with Ti) to fix nitrogen so boron stays effective | ≥ 0.02 | 0.03 |
| Fe | balance | — |
23B2 +U+C — frequently asked
What is 23B2 +U+C used for?
23B2 +U+C is typically used for bolts, fasteners and pins. In short: most formable boron grade; easier to weld than 23MnB3; low-cost cold-heading steel.
What is the yield strength of 23B2 +U+C?
23B2 +U+C has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 650 MPa (94.3 ksi) — stronger than 73% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 23B2 +U+C easy to machine?
Reasonably — machinability is rated good (66/100, better than 95% of steel grades). Machines like a soft 1020/1023 — gummy in the spheroidized state; use sharp positive-rake tooling, good chip breaking, or machine after Q&T at ~25 HRC.
Can 23B2 +U+C be welded?
Yes — weldability is rated very good (70/100). Weldable (CEV ≈ 0.30–0.35) with SMAW/GMAW, but boron sharply increases HAZ hardenability — preheat 100–150 °C on heavy sections and avoid welding hardened fasteners.
What surface finishes work on 23B2 +U+C?
No inherent corrosion resistance: zinc or zinc-nickel electroplate (with bake for hydrogen relief), zinc-flake dip-spin, or phosphate-and-oil; not anodizable.
Can 23B2 +U+C be formed, bent or molded?
Designed for multi-station cold heading and cold extrusion in +AC or +AC+C; phosphate + soap or polymer lubricant coating, and inter-pass spheroidizing for very severe upsets.
What is the maximum service temperature of 23B2 +U+C?
23B2 +U+C 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.
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 and delivery conditions — 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)
- ASTM A370 hardness conversion tables — ASTM (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.