Steel 12CrNi3 QT-35-40HRC
Hardness band
EN 12CrNi3
Higher-strength through-hardened option for heavily loaded shafts where surface carburizing is not applied.
Values for the QT-35-40HRC condition
Other 12CrNi3 tempers and conditions
12CrNi3 is listed in 8 conditions; see the grade overview at 12CrNi3.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for best machinability and dimensional stability before carburizing or final hardening. | 420 | 660 | 22 | 200 HB | — |
Hot rolled | Cheapest stock form for rough machining or forging blanks before final carburizing. | 450 | 720 | 18 | 18 HRC | 7 % IACS |
Normalized | Grain refinement and uniform structure for forgings prior to carburizing; better than as-rolled toughness. | 520 | 780 | 18 | 22 HRC | 6.9 % IACS |
Cold drawn | Small-diameter bright bar with tight tolerance for pins and small shafts machined with little stock removal. | 650 | 800 | 10 | 24 HRC | 6.8 % IACS |
quenched and high tempered (through-hardened shaft condition) | Pick for through-hardened shafts/couplings that will not be carburized but need good machinability after heat treatment. | 780 | 950 | 16 | 30 HRC | — |
QTDefault Quenched and tempered | Reference condition of the standard; gives the quoted 930 MPa class strength with high toughness for through-hardened shafts and gear blanks. | 790 | 990 | 14 | 31 HRC | — |
Carburized and hardened | The intended service condition: hard wear- and pitting-resistant case over a tough Ni-Cr core for gears, gear shafts and worms. | 820 | 1,050 | 11 | 60 HRC | — |
QT-35-40HRCThis page quenched and medium tempered | Higher-strength through-hardened option for heavily loaded shafts where surface carburizing is not applied. | 980 | 1,180 | 12 | 38 HRC | — |
What is 12CrNi3 QT-35-40HRC?
12CrNi3 QT-35-40HRC is 12CrNi3 heat treated to QT-35-40HRC — higher-strength through-hardened option for heavily loaded shafts where surface carburizing is not applied. 12CrNi3 QT-35-40HRC has a yield strength of 980 MPa (142 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 91% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi). 12CrNi3 QT-35-40HRC 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). QT is the default condition FabDigit quotes; QT-35-40HRC is available on request or by drawing note.
Advantages
- High strength — 980 MPa (142 ksi), better than 91% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Difficult to machine — 32/100, worse than 87% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
- Low electrical conductivity — 6.5 % IACS, worse than 77% of steel grades
12CrNi3 QT-35-40HRC properties
Typical room-temperature values for 12CrNi3 QT-35-40HRC; 10 are specific to this condition. Other listed values are 12CrNi3 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
12CrNi3 QT-35-40HRC 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
12CrNi3 QT-35-40HRC has a yield strength of 980 MPa (142 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 91% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
12CrNi3 QT-35-40HRC is rated for continuous service to 200°C (392 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
12CrNi3 QT-35-40HRC conducts electricity at 6.5 % IACS, worse than 77% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 12CrNi3 QT-35-40HRC takes about 33 MJ of energy and emits 2.4 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 30%.
Manufacturability7
12CrNi3 QT-35-40HRC's machinability is poor (32/100, worse than 87% of steel grades); weldability fair (40/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 12CrNi3 QT-35-40HRC
Is 12CrNi3 easy to machine?
Machine in the annealed/high-tempered state (≤269 HB) with coated carbide, moderate speed and generous coolant; the Ni-rich structure is gummy and work-hardens, so finish grind after case hardening.
Can 12CrNi3 be welded?
Weldable only with care — preheat 150–250 °C, low-hydrogen Ni-alloy filler, and post-weld temper/stress relief; never weld after carburizing.
Can 12CrNi3 be formed, bent or molded?
Forge at 1150–850 °C followed by slow cooling plus normalizing/annealing; cold forming is limited and heavy bends should be hot-formed.
What surface finishes work on 12CrNi3?
No anodizing; protect with phosphating, black oxide, zinc or Ni plating (bake for hydrogen), or oil after grinding — case-hardened surfaces polish and hone well.
12CrNi3 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 | 0.1 – 0.17 | 0.13 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.3 – 0.6 | 0.45 |
| Cr | 0.6 – 0.9 | 0.75 |
| Ni | 2.75 – 3.25 | 3 |
| Pmax, high-grade steel | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Curesidual max | ≤ 0.25 | — |
| Moresidual max, not intentionally added | ≤ 0.15 | — |
| Fe | balance | — |
12CrNi3 QT-35-40HRC — frequently asked
What is 12CrNi3 QT-35-40HRC used for?
12CrNi3 QT-35-40HRC is typically used for gears, shafts and pins. In short: high core toughness; ni-rich carburizing steel; difficult to machine.
What is the yield strength of 12CrNi3 QT-35-40HRC?
12CrNi3 QT-35-40HRC has a typical yield strength of 980 MPa (142 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 12CrNi3 QT-35-40HRC easy to machine?
Not especially — machinability is rated poor (32/100, worse than 87% of steel grades). Machine in the annealed/high-tempered state (≤269 HB) with coated carbide, moderate speed and generous coolant; the Ni-rich structure is gummy and work-hardens, so finish grind after case hardening.
Can 12CrNi3 QT-35-40HRC be welded?
With care — weldability is rated fair (40/100). Weldable only with care — preheat 150–250 °C, low-hydrogen Ni-alloy filler, and post-weld temper/stress relief; never weld after carburizing.
What surface finishes work on 12CrNi3 QT-35-40HRC?
No anodizing; protect with phosphating, black oxide, zinc or Ni plating (bake for hydrogen), or oil after grinding — case-hardened surfaces polish and hone well.
Can 12CrNi3 QT-35-40HRC be formed, bent or molded?
Forge at 1150–850 °C followed by slow cooling plus normalizing/annealing; cold forming is limited and heavy bends should be hot-formed.
What is the maximum service temperature of 12CrNi3 QT-35-40HRC?
12CrNi3 QT-35-40HRC 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 12CrNi3-QT and 12CrNi3-A?
QT is the default condition — reference condition of the standard; gives the quoted 930 MPa class strength with high toughness for through-hardened shafts and gear blanks. A: choose for best machinability and dimensional stability before carburizing or final hardening. Yield strength is 790 MPa in QT versus 420 MPa in A.
Sources
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4: Heat Treating (carburizing of Ni-Cr steels) — ASM International (1991)
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.