Steel 40Cr-IH (Induction hardened)
Heat-treated state
GB 40Cr
Choose when only the running surface (journal, spline, gear tooth) needs 50+ HRC wear resistance over a tough core.
Values for the IH 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 | — |
IHThis page 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 |
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-IH?
40Cr-IH is 40Cr heat treated to IH — choose when only the running surface (journal, spline, gear tooth) needs 50+ HRC wear resistance over a tough core. 40Cr-IH 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 12% and the elastic modulus is 210 GPa (30.5 Msi). 40Cr-IH 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; IH is available on request or by drawing note.
Advantages
- High strength — 830 MPa (120 ksi), better than 87% of steel grades
Limitations
- Difficult to machine — 12/100, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Low fracture toughness — 40 MPa·√m (36.4 ksi·√in), worse than 92% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
40Cr-IH properties
Typical room-temperature values for 40Cr-IH; 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-IH 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-IH 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 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
40Cr-IH is rated for continuous service to 200°C (392 °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-IH conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 40Cr-IH 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-IH's machinability is not recommended (12/100, worse than 99% of steel grades); weldability poor (15/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 40Cr-IH
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-IH — frequently asked
What is 40Cr-IH used for?
40Cr-IH is typically used for drive shafts, industrial bolts and crankshafts. In short: chrome alloy machining bar.
What is the yield strength of 40Cr-IH?
40Cr-IH 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-IH easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% 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-IH be welded?
Not readily — weldability is rated poor (15/100). 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-IH?
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-IH 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-IH?
40Cr-IH is rated for continuous use to about 200°C (392 °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-IH?
Yes — 40Cr-IH 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.