Steel 12CrNi3
EN 12CrNi3
12CrNi3 is a nickel-chromium case-hardening steel used where the carburized case must sit on a very tough, high-strength core.
Reference datasheet — 12CrNi3 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
12CrNi3 tempers and conditions
12CrNi3 is supplied in 8 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
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 | — |
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?
12CrNi3 is a nickel-chromium case-hardening steel used where the carburized case must sit on a very tough, high-strength core. It serves medium to heavily loaded gears, shafts and pins, and is supplied as hot-rolled, annealed, normalized, cold-drawn and quenched-and-tempered bar. Quenched-and-tempered core values are about 790 MPa yield, 990 MPa tensile, 14% elongation and 300 HB (31 HRC). The nickel-rich matrix is gummy and work-hardening (machinability score 40), tempering limits service to about 200 °C, and welding needs preheat plus post-weld temper. 20Cr2Ni4 (9310) is the step up for heavier duty. 12CrNi3 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). 12CrNi3 has a yield strength of 790 MPa (115 ksi) and a tensile strength of 990 MPa (144 ksi) — stronger than 86% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
What is 12CrNi3 used for?
- gears
- shafts
- pins
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High strength — 790 MPa (115 ksi), better than 86% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% 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
- Difficult to machine — 40/100, worse than 77% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
12CrNi3 properties
Typical room-temperature values for 12CrNi3-QT; bars are the position among steel grades.
Physical3
12CrNi3 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 has a yield strength of 790 MPa (115 ksi) and a tensile strength of 990 MPa (144 ksi) — stronger than 86% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
12CrNi3 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 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 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's machinability is fair (40/100, worse than 77% of steel grades); weldability fair (40/100); formability fair (35/100).
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. 12CrNi3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 12CrNi3
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.
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 |
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.
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
How much does 12CrNi3 cost?
12CrNi3 is a standard-cost steel ($$), cheaper than about 71% 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.
12CrNi3 — frequently asked
What is 12CrNi3 used for?
12CrNi3 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?
12CrNi3 has a typical yield strength of 790 MPa (115 ksi) and a tensile strength of 990 MPa (144 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 12CrNi3 easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% 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 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?
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 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?
12CrNi3 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.
How much does 12CrNi3 cost?
12CrNi3 is a standard-cost steel ($$), cheaper than about 71% 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
- 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; 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.