Steel 10B22-CN
Heat-treated state
EN 10B22 · UNS G10221
CN = carbonitrided / case hardened
Pick for self-drilling, thread-forming and tapping screws needing a hard case over a tough tempered core (SAE J78/J81 style).
Values for the CN condition
Other 10B22 tempers and conditions
10B22 is listed in 9 conditions; see the grade overview at 10B22.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for severe multi-station cold heading/extrusion of long bolts and complex flange heads. | 290 | 440 | 30 | 130 HB | — |
Hot rolled | Mill-supplied hot-rolled coil or bar before annealing/drawing; cheapest form for hot forging or further processing. | 330 | 500 | 25 | 143 HB | — |
Normalized | Uniform fine-grain structure after hot forging; used when parts are machined rather than quenched. | 345 | 510 | 26 | 150 HB | 10.5 % IACS |
CDDefault Cold drawn | Standard stocked condition: annealed-and-drawn wire/bar ready for cold heading, thread rolling or machining before heat treatment. | 525 | 620 | 13 | 180 HB | — |
Q&T Grade 5 | Oil-quench and temper ~500 °C for inch-series Grade 5 bolts up to about 1/2–5/8 in. | 720 | 900 | 16 | 29 HRC | — |
quenched and tempered to ISO 898-1 property class 8.8 | The volume workhorse condition for metric M5–M16 class 8.8 bolts and screws. | 720 | 870 | 15 | 28 HRC | — |
quenched and tempered to property class 9.8 | Intermediate class for small metric screws (≤ M16) where 8.8 is not enough but 10.9 tempering embrittlement is a concern. | 780 | 950 | 12 | 31 HRC | 9 % IACS |
CNThis page Carbonitrided / case hardened | Pick for self-drilling, thread-forming and tapping screws needing a hard case over a tough tempered core (SAE J78/J81 style). | 950 | 1,100 | 8 | 34 HRC | 9.5 % IACS |
quenched and tempered to property class 10.9 (small sizes) | Only for thin sections (typically ≤ M12–M16) where boron hardenability still gives ≥90 % martensite at the core. | 990 | 1,100 | 10 | 35 HRC | — |
What is 10B22-CN?
10B22-CN is 10B22 heat treated to CN — pick for self-drilling, thread-forming and tapping screws needing a hard case over a tough tempered core (SAE J78/J81 style). 10B22-CN has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Elongation at break is 8% and the elastic modulus is 205 GPa (29.7 Msi). 10B22-CN has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F). CD is the default condition FabDigit quotes; CN is available on request or by drawing note.
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High strength — 950 MPa (138 ksi), better than 91% of steel grades
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Difficult to machine — 15/100, worse than 98% of steel grades
- Limited ductility — 8%, worse than 95% of steel grades
- Limited formability — 10/100, worse than 95% of steel grades
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 86% of steel grades
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
10B22-CN properties
Typical room-temperature values for 10B22-CN; 23 are specific to this condition. Other listed values are 10B22 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
10B22-CN has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical14
10B22-CN has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Elongation at break is 8% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
10B22-CN is rated for continuous service to 250°C (482 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
10B22-CN conducts electricity at 9.5 % IACS, better than 75% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 10B22-CN 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
10B22-CN's machinability is poor (15/100, worse than 98% of steel grades); weldability poor (25/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 10B22-CN
Is 10B22 easy to machine?
Machines like 1022 (~65 % of AISI 1212); spheroidized material is gummy — use sharp positive-rake tools and good chip breaking, and prefer normalized or lightly drawn stock for turning.
Can 10B22 be welded?
Weldable by RSW/MIG/MAG with CE ≈ 0.40–0.45, but boron sharply raises HAZ hardenability — limit heat input, use low-hydrogen consumables and preheat 100–150 °C on sections over ~15 mm; do not weld after quench-and-temper.
Can 10B22 be formed, bent or molded?
Excellent cold heading, extrusion and thread rolling in the spheroidize-annealed/drawn condition (phosphate + soap or polymer lube); hot forge 1050–1200 °C, austenitize 860–900 °C, oil quench, temper 400–550 °C.
What surface finishes work on 10B22?
No inherent corrosion resistance: zinc electroplate, zinc-nickel, hot-dip galvanizing or zinc-flake coating; bake 190–230 °C within 4 h after plating on parts above ~320 HV to avoid hydrogen embrittlement.
10B22 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 |
|---|---|---|
| CSAE J403 boron grade | 0.19 – 0.25 | 0.22 |
| Mn | 0.7 – 1 | 0.85 |
| Sikilled steel; CHQ wire often ≤0.10 Si for softer heading | 0.1 – 0.3 | 0.2 |
| P | ≤ 0.03 | 0.02 |
| Smax; cold-heading quality usually restricted to ≤0.035 | ≤ 0.05 | 0.02 |
| Beffective (soluble) boron; Ti and/or Al added to fix N | 5×10⁻⁴ – 0 | 0 |
| Tinitrogen fixer, producer practice | ≤ 0.06 | 0.03 |
| Algrain refining / N fixing, producer practice | 0.02 – 0.06 | 0.03 |
| Fe | balance | — |
10B22-CN — frequently asked
What is 10B22-CN used for?
10B22-CN is typically used for bolts, fasteners and cold-formed parts. In short: high cold-heading formability; boron replaces alloy content; high-volume fastener wire.
What is the yield strength of 10B22-CN?
10B22-CN has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 10B22-CN easy to machine?
Not especially — machinability is rated poor (15/100, worse than 98% of steel grades). Machines like 1022 (~65 % of AISI 1212); spheroidized material is gummy — use sharp positive-rake tools and good chip breaking, and prefer normalized or lightly drawn stock for turning.
Can 10B22-CN be welded?
Not readily — weldability is rated poor (25/100). Weldable by RSW/MIG/MAG with CE ≈ 0.40–0.45, but boron sharply raises HAZ hardenability — limit heat input, use low-hydrogen consumables and preheat 100–150 °C on sections over ~15 mm; do not weld after quench-and-temper.
What surface finishes work on 10B22-CN?
No inherent corrosion resistance: zinc electroplate, zinc-nickel, hot-dip galvanizing or zinc-flake coating; bake 190–230 °C within 4 h after plating on parts above ~320 HV to avoid hydrogen embrittlement.
Can 10B22-CN be formed, bent or molded?
Excellent cold heading, extrusion and thread rolling in the spheroidize-annealed/drawn condition (phosphate + soap or polymer lube); hot forge 1050–1200 °C, austenitize 860–900 °C, oil quench, temper 400–550 °C.
What is the maximum service temperature of 10B22-CN?
10B22-CN is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 10B22-CD and 10B22 QT-109?
CD is the default condition — standard stocked condition: annealed-and-drawn wire/bar ready for cold heading, thread rolling or machining before heat treatment. QT-109: only for thin sections (typically ≤ M12–M16) where boron hardenability still gives ≥90 % martensite at the core. Yield strength is 525 MPa in CD versus 990 MPa in QT-109.
Sources
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- SAE J429 — Mechanical and Material Requirements for Externally Threaded Fasteners — SAE International (2014)
- ISO 898-1 — Mechanical properties of fasteners made of carbon steel and alloy steel — 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 hardenability) — ASM International (1991)
- Mysteel / SMM — Mysteel (2025)
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.