Steel 16NC6 CH-40
Heat-treated state
EN 16NC6
CH-40 = carburized and tempered, core section 16–40 mm
Same case-hardening cycle on heavier sections; lower core strength because of the steel's limited hardenability.
Values for the CH-40 condition
Other 16NC6 tempers and conditions
16NC6 is listed in 9 conditions; see the grade overview at 16NC6.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Treated to hardness range | Choose when the buyer specifies a narrow delivery hardness band for automatic machining or cold forming lines. | 340 | 540 | 24 | 160 HB | 8 % IACS |
+ADefault Annealed | Standard stock condition for gear-blank machining and cold forming before carburizing. | 350 | 560 | 22 | 170 HB | — |
Treated to ferrite–pearlite structure and hardness range | Delivery condition specified when uniform ferrite-pearlite microstructure is needed for consistent gear-cutting and distortion control. | 380 | 600 | 20 | 180 HB | 8 % IACS |
Hot rolled | Cheapest mill condition for forging stock or parts that will be normalized/annealed before machining. | 390 | 620 | 18 | 11 HRC | 8 % IACS |
Normalized | Used to refine forging grain and give uniform machining structure before carburizing. | 420 | 650 | 19 | 195 HB | — |
CH-40This page Carburized and tempered, core section 16–40 mm | Same case-hardening cycle on heavier sections; lower core strength because of the steel's limited hardenability. | 520 | 830 | 12 | 59 HRC | — |
Cold drawn | Bright, dimensionally accurate bar for pins and shafts machined with minimal stock removal. | 550 | 700 | 11 | 215 HB | — |
Carburized and hardened | Final in-service condition for gears and pins: hard wear-resistant case with a tough, high-strength core in thin sections. | 680 | 950 | 10 | 60 HRC | — |
Q&T 28–34 HRC | Occasional condition for small non-wearing parts needing a tough medium-hard body without a case. | 750 | 950 | 14 | 31 HRC | — |
What is 16NC6 CH-40?
16NC6 CH-40 is 16NC6 heat treated to CH-40 — same case-hardening cycle on heavier sections; lower core strength because of the steel's limited hardenability. 16NC6 CH-40 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 67% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi). 16NC6 CH-40 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). +A is the default condition FabDigit quotes; CH-40 is available on request or by drawing note.
Advantages
- Forms and bends easily — 65/100, better than 81% of steel grades
Limitations
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Difficult to machine — 15/100, worse than 98% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
16NC6 CH-40 properties
Typical room-temperature values for 16NC6 CH-40; 10 are specific to this condition. Other listed values are 16NC6 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
16NC6 CH-40 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
16NC6 CH-40 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 67% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
16NC6 CH-40 is rated for continuous service to 180°C (356 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
16NC6 CH-40 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 16NC6 CH-40 takes about 31 MJ of energy and emits 2.2 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 30%.
Manufacturability7
16NC6 CH-40's machinability is poor (15/100, worse than 98% of steel grades); weldability good (60/100); formability good (65/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 16NC6 CH-40
Is 16NC6 easy to machine?
Machine fully in the annealed or cold-drawn state with carbide or coated HSS at ~60 % of 1212 rates; after carburizing only grinding or hard turning with CBN is practical.
Can 16NC6 be welded?
Weldable before carburizing by MIG/TIG with low-hydrogen filler and 150–250 °C preheat; avoid welding after case hardening because the case will crack.
Can 16NC6 be formed, bent or molded?
Good cold heading and upsetting in the +TH/+A conditions; hot forge 1100–1150 °C and normalize afterwards to refine grain.
What surface finishes work on 16NC6?
Not anodizable — protect with oil, manganese phosphate, black oxide or zinc plating (bake to avoid hydrogen embrittlement on hardened parts); case-hardened surfaces polish and grind well.
16NC6 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 |
|---|---|---|
| CAFNOR designation index | 0.13 – 0.19 | 0.16 |
| Si | 0.15 – 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| NiN6 → ≈1.5 % Ni | 1.2 – 1.6 | 1.4 |
| Cr | 0.8 – 1.1 | 0.95 |
| Moresidual | ≤ 0.1 | 0.03 |
| P | ≤ 0.04 | 0.02 |
| Smax; 0.020–0.035 for machinability grades | ≤ 0.04 | 0.02 |
| Curesidual | ≤ 0.3 | 0.15 |
| Fe | balance | — |
16NC6 CH-40 — frequently asked
What is 16NC6 CH-40 used for?
16NC6 CH-40 is typically used for gears, pins and small shafts. In short: easy-forming carburizing steel; AISI 5115 equivalent; light-duty gear grade.
What is the yield strength of 16NC6 CH-40?
16NC6 CH-40 has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 67% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 16NC6 CH-40 easy to machine?
Not especially — machinability is rated poor (15/100, worse than 98% of steel grades). Machine fully in the annealed or cold-drawn state with carbide or coated HSS at ~60 % of 1212 rates; after carburizing only grinding or hard turning with CBN is practical.
Can 16NC6 CH-40 be welded?
Yes — weldability is rated good (60/100). Weldable before carburizing by MIG/TIG with low-hydrogen filler and 150–250 °C preheat; avoid welding after case hardening because the case will crack.
What surface finishes work on 16NC6 CH-40?
Not anodizable — protect with oil, manganese phosphate, black oxide or zinc plating (bake to avoid hydrogen embrittlement on hardened parts); case-hardened surfaces polish and grind well.
Can 16NC6 CH-40 be formed, bent or molded?
Good cold heading and upsetting in the +TH/+A conditions; hot forge 1100–1150 °C and normalize afterwards to refine grain.
What is the maximum service temperature of 16NC6 CH-40?
16NC6 CH-40 is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 16NC6 +A and 16NC6-CH?
+A is the default condition — standard stock condition for gear-blank machining and cold forming before carburizing. CH: final in-service condition for gears and pins: hard wear-resistant case with a tough, high-strength core in thin sections. Yield strength is 350 MPa in +A versus 680 MPa in CH.
Sources
- NF A 35-551 — Aciers pour cémentation (16NC6) — AFNOR (1987)
- EN 10084 — Case hardening steels, technical delivery conditions — CEN (2008)
- SAE J404 — Chemical Compositions of SAE Alloy Steels (5115) — SAE International (2009)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals (carburizing) — ASM International (2013)
- Machinery's Handbook, 31st ed. (machinability ratings) — Industrial Press (2020)
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.