Steel 40CrNi
GB 40CrNi
40CrNi is a nickel-chromium quenched-and-tempered structural steel (SAE 3140) offering better hardenability and core toughness than 40Cr at similar carbon content.
Reference datasheet — 40CrNi is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the QT condition
40CrNi tempers and conditions
40CrNi is supplied in 11 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition for deep machining, cold forming or before final quench and temper. | 420 | 690 | 21 | 200 HB | — |
Hot rolled | Mill as-rolled bar bought for subsequent forging or full heat treatment by the user. | 480 | 780 | 16 | 230 HB | — |
Normalized | Grain refinement and uniform structure after forging; used when full Q&T strength is not required. | 540 | 850 | 18 | 23 HRC | 7.8 % IACS |
Cold drawn | Bright, close-tolerance bar for parts machined without further heat treatment. | 680 | 830 | 11 | 245 HB | — |
Q&T 25–30 HRC (high-temperature temper ~600 °C) | Toughest Q&T level; pick for large sections, welded-then-tempered parts or heavy shock loading. | 780 | 930 | 16 | 28 HRC | — |
QTDefault Quenched and tempered | Standard delivery condition — oil quenched from 820 °C and tempered at 500 °C to GB/T 3077 — giving 840 MPa yield, ~1020 MPa tensile and ≥55 J impact for shafts, gears and rods. | 840 | 1,020 | 12 | 31 HRC | — |
Q&T core with induction-hardened surface (52–58 HRC case) | Choose for journals, spline and gear tooth flanks needing wear resistance and compressive residual stress on a tough core. | 840 | 1,020 | 11 | 55 HRC | 7.3 % IACS |
Q&T 30–34 HRC (temper ~540 °C) | Balanced strength/toughness hardness band commonly specified for gear blanks and drive shafts. | 880 | 1,050 | 14 | 32 HRC | — |
Q&T 34–38 HRC (temper ~480 °C) | Higher-strength band for high-load bolts, rods and small-section shafts where toughness margin is lower. | 1,030 | 1,180 | 12 | 36 HRC | — |
Q&T 38–42 HRC (temper ~400 °C) | Maximum practical Q&T hardness for this grade — high wear resistance, reduced impact energy and machinability. | 1,180 | 1,330 | 10 | 40 HRC | — |
As-quenched | Intermediate state only — must be tempered immediately; quoted for hardenability/hardness checks. | 1,550 | 2,000 | 2 | 55 HRC | 6.5 % IACS |
What is 40CrNi?
40CrNi is a nickel-chromium quenched-and-tempered structural steel (SAE 3140) offering better hardenability and core toughness than 40Cr at similar carbon content. It is used for medium-heavy shafts, gears, connecting rods and bolts, and is stocked as hot-rolled, annealed, normalized and cold-drawn bar plus QT bands from 25–30 HRC up to 38–42 HRC and QT + induction hardened, with default values of 840 MPa yield, 1020 MPa tensile, 12 % elongation and 300 HB (31 HRC). Weldability is poor (CE ≈ 0.85), corrosion resistance is nil and service tops out near 400 °C; 42CrMo (4140) is more widely available and 40CrNiMo suits larger sections. 40CrNi has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). 40CrNi has a yield strength of 840 MPa (122 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).
What is 40CrNi used for?
- shafts
- gears
- connecting rods
- bolts
Advantages
- High strength — 840 MPa (122 ksi), better than 87% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited ductility — 12%, worse than 84% of steel grades
40CrNi properties
Typical room-temperature values for 40CrNi-QT; bars are the position among steel grades.
Physical3
40CrNi has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
40CrNi has a yield strength of 840 MPa (122 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
40CrNi is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
40CrNi conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 40CrNi takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.
Manufacturability7
40CrNi's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (30/100); formability poor (25/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 40CrNi is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 40CrNi
Is 40CrNi easy to machine?
Best machined annealed (≤250 HB) or after tempering to 28–32 HRC; use rigid setups, coated carbide, 80–140 m/min, and expect ~50 % of 1212 free-cutting rate.
Can 40CrNi be welded?
Poor weldability (CE ≈ 0.85): preheat 250–350 °C, low-hydrogen electrodes, and temper immediately after welding; avoid welding on fully hardened parts.
Can 40CrNi be formed, bent or molded?
Hot forge 1150–850 °C then slow cool/anneal; cold bending or upsetting only in the annealed state with generous radii.
40CrNi 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 |
|---|---|---|
| CGB/T 3077-2015 | 0.37 – 0.44 | 0.4 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.5 – 0.8 | 0.65 |
| Cr | 0.45 – 0.75 | 0.6 |
| Ni | 1 – 1.4 | 1.2 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Curesidual, max | ≤ 0.3 | 0.15 |
| Fe | balance |
What surface finishes work on 40CrNi?
Not corrosion resistant — protect with black oxide, phosphate + oil, zinc or hard chrome plating (bake at 190 °C for hydrogen relief); nitriding or induction hardening adds wear resistance.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 40CrNi in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 3140
How much does 40CrNi cost?
40CrNi is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
40CrNi — frequently asked
What is 40CrNi used for?
40CrNi is typically used for shafts, gears, connecting rods and bolts. In short: tougher than 40Cr; deep-hardening Ni-Cr grade; limited stock availability.
What is the yield strength of 40CrNi?
40CrNi has a typical yield strength of 840 MPa (122 ksi) and a tensile strength of 1,020 MPa (148 ksi) — stronger than 87% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 40CrNi easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Best machined annealed (≤250 HB) or after tempering to 28–32 HRC; use rigid setups, coated carbide, 80–140 m/min, and expect ~50 % of 1212 free-cutting rate.
Can 40CrNi be welded?
Not readily — weldability is rated poor (30/100). Poor weldability (CE ≈ 0.85): preheat 250–350 °C, low-hydrogen electrodes, and temper immediately after welding; avoid welding on fully hardened parts.
What surface finishes work on 40CrNi?
Not corrosion resistant — protect with black oxide, phosphate + oil, zinc or hard chrome plating (bake at 190 °C for hydrogen relief); nitriding or induction hardening adds wear resistance.
Can 40CrNi be formed, bent or molded?
Hot forge 1150–850 °C then slow cool/anneal; cold bending or upsetting only in the annealed state with generous radii.
What is the maximum service temperature of 40CrNi?
40CrNi is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 40CrNi-QT and 40CrNi-Q?
QT is the default condition — standard delivery condition — oil quenched from 820 °C and tempered at 500 °C to GB/T 3077 — giving 840 MPa yield, ~1020 MPa tensile and ≥55 J impact for shafts, gears and rods. Q: intermediate state only — must be tempered immediately; quoted for hardenability/hardness checks. Yield strength is 840 MPa in QT versus 1,550 MPa in Q.
How much does 40CrNi cost?
40CrNi is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- GB/T 3077 Alloy structural steels — SAC (China) (2015)
- SAE J404 / AISI 3140 chemical composition — SAE International (2009)
- 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.