Steel 40Cr Nitrided
Finish state
GB 40Cr
Use for low-distortion wear and scuffing resistance on already-finished Q&T parts; case is thin (0.2–0.4 mm).
Values for the Nitrided condition
Other 40Cr tempers and conditions
40Cr is listed in 10 conditions; see the grade overview at 40Cr.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Temper | Softest condition (≤207 HB per GB/T 3077) for deep machining, cold forming or before final hardening. | 400 | 680 | 22 | 187 HB | — |
HRDefault Hot rolled | Standard stocked as-rolled bar; buy this and heat treat after rough machining. | 430 | 720 | 16 | 210 HB | — |
Heat Treat State | Air-cooled from ~860 °C for uniform fine pearlitic structure and predictable machining before Q&T. | 500 | 800 | 18 | 20 HRC | 8 % IACS |
Cold rolled | Cold-rolled strip/sheet for stamped and formed parts that will be hardened later. | 620 | 800 | 10 | 22 HRC | 8 % IACS |
Cold drawn | Cold-drawn bright bar: tighter tolerance, better surface and free-er chip than hot rolled. | 650 | 790 | 12 | 229 HB | — |
Q&T to 28–32 HRC | Toughness-first condition for large shafts and parts still to be machined after heat treatment. | 790 | 950 | 14 | 30 HRC | — |
Quenched and tempered | Standard GB/T 3077 delivery-condition property set; the usual choice for shafts, gears and high-strength bolts. | 830 | 1,020 | 12 | 31 HRC | — |
Induction hardened | Choose when only the running surface (journal, spline, gear tooth) needs 50+ HRC wear resistance over a tough core. | 830 | 1,020 | 12 | 55 HRC | 7 % IACS |
NitridedThis page Gas/ion nitrided (after Q&T) | Use for low-distortion wear and scuffing resistance on already-finished Q&T parts; case is thin (0.2–0.4 mm). | 830 | 1,020 | 11 | 57 HRC | 8 % IACS |
Q&T to 35–40 HRC | Higher-strength temper for gears, couplings and wear-loaded parts; toughness and machinability drop. | 1,050 | 1,200 | 10 | 38 HRC | — |
What is 40Cr Nitrided?
40Cr Nitrided is 40Cr supplied in the Nitrided condition — use for low-distortion wear and scuffing resistance on already-finished Q&T parts; case is thin (0.2–0.4 mm). 40Cr Nitrided has a yield strength of 830 MPa (120 ksi) and a tensile strength of 1,020 MPa (148 ksi) — stronger than 87% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi). 40Cr Nitrided 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). HR is the default condition FabDigit quotes; Nitrided is available on request or by drawing note.
Advantages
- High strength — 830 MPa (120 ksi), better than 87% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Difficult to weld — 5/100, worse than 100% of steel grades
- Limited formability — 3/100, worse than 99% of steel grades
- Low fracture toughness — 42 MPa·√m (38.2 ksi·√in), worse than 92% of steel grades
- Limited ductility — 11%, worse than 89% of steel grades
40Cr Nitrided properties
Typical room-temperature values for 40Cr Nitrided; 21 are specific to this condition. Other listed values are 40Cr reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
40Cr Nitrided 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).
Mechanical16
40Cr Nitrided has a yield strength of 830 MPa (120 ksi) and a tensile strength of 1,020 MPa (148 ksi) — stronger than 87% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
40Cr Nitrided is rated for continuous service to 450°C (842 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
40Cr Nitrided conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of 40Cr Nitrided takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 35%.
Manufacturability7
40Cr Nitrided's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (5/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 40Cr Nitrided
Is 40Cr easy to machine?
Best machined annealed or normalized at 180–230 HB with carbide tooling (~120–180 m/min); above 35 HRC switch to coated carbide/CBN and reduce feed.
Can 40Cr be welded?
Weldable with care only — preheat 200–300 °C, low-hydrogen consumables, and temper immediately after welding; avoid welding fully hardened parts.
Can 40Cr be formed, bent or molded?
Hot forge 1150–850 °C then normalize; cold bending only in the annealed condition with generous radii (≥3t).
What surface finishes work on 40Cr?
No native corrosion protection: use black oxide, manganese phosphate, zinc or hard chrome plating (bake to de-embrittle above ~1000 MPa); polishes well after Q&T.
40Cr 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 | 0.37 – 0.44 | 0.4 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.5 – 0.8 | 0.65 |
| Cr | 0.8 – 1.1 | 0.95 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.25 | — |
| Moresidual, not intentionally added | ≤ 0.1 | — |
| P0.025 max for high-grade quality | ≤ 0.04 | — |
| S0.025 max for high-grade quality | ≤ 0.04 | — |
| Fe | balance | — |
40Cr Nitrided — frequently asked
What is 40Cr Nitrided used for?
40Cr Nitrided is typically used for drive shafts, industrial bolts and crankshafts. In short: chrome alloy machining bar.
What is the yield strength of 40Cr Nitrided?
40Cr Nitrided has a typical yield strength of 830 MPa (120 ksi) and a tensile strength of 1,020 MPa (148 ksi) — stronger than 87% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 40Cr Nitrided easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Best machined annealed or normalized at 180–230 HB with carbide tooling (~120–180 m/min); above 35 HRC switch to coated carbide/CBN and reduce feed.
Can 40Cr Nitrided be welded?
Not readily — weldability is rated not recommended (5/100). Weldable with care only — preheat 200–300 °C, low-hydrogen consumables, and temper immediately after welding; avoid welding fully hardened parts.
What surface finishes work on 40Cr Nitrided?
No native corrosion protection: use black oxide, manganese phosphate, zinc or hard chrome plating (bake to de-embrittle above ~1000 MPa); polishes well after Q&T.
Can 40Cr Nitrided be formed, bent or molded?
Hot forge 1150–850 °C then normalize; cold bending only in the annealed condition with generous radii (≥3t).
What is the maximum service temperature of 40Cr Nitrided?
40Cr Nitrided is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 40Cr-HR and 40Cr-IH?
HR is the default condition — standard stocked as-rolled bar; buy this and heat treat after rough machining. IH: choose when only the running surface (journal, spline, gear tooth) needs 50+ HRC wear resistance over a tough core. Yield strength is 430 MPa in HR versus 830 MPa in IH.
Can FabDigit make parts in 40Cr Nitrided?
Yes — 40Cr Nitrided is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 3077 Alloy structural steels (2015)
- SAE J404 Chemical Compositions of SAE Alloy Steels (5140) — SAE International (2018)
- EN 10083-3 (41Cr4 / 1.7035) — CEN (2006)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.