Steel 12KhN3A
GOST 12KhN3A (12ХН3А)
12KhN3A is a GOST nickel-chromium carburizing steel with about 3 % Ni, giving high core toughness for demanding gear and shaft work.
Reference datasheet — 12KhN3A 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
12KhN3A tempers and conditions
12KhN3A 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 | Softest condition for heavy machining, deep drilling or cold forming before case hardening. | 380 | 620 | 22 | 200 HB | — |
Hot rolled | Mill condition of round bar and forging stock, machined then heat treated by the part maker. | 440 | 700 | 18 | 19 HRC | 7.5 % IACS |
Normalized | Grain refinement and uniform machinable structure prior to carburizing of forged parts. | 520 | 760 | 18 | 20 HRC | 7.5 % IACS |
Cold drawn | Bright bar with tight tolerance for small pins and shafts made with minimal machining. | 660 | 800 | 10 | 22 HRC | 7 % IACS |
Q&T high temper | Choose when a non-carburized, dimensionally stable tough shaft or fastener body is needed rather than a hard case. | 700 | 850 | 17 | 26 HRC | — |
QTDefault Quenched and tempered | Standard GOST acceptance condition; use for the tough core strength of carburized parts or for through-hardened medium-duty parts. | 760 | 980 | 13 | 30 HRC | — |
Carburized, hardened and finish ground | Final precision condition for ground gear teeth and bearing journals where distortion must be removed after case hardening. | 830 | 1,080 | 11 | 60 HRC | 6.5 % IACS |
Carburized 900–930 °C + oil quench + 160–200 °C temper | The service condition for gears, worms and splines — very hard wear-resistant case over the tough Ni-Cr core. | 850 | 1,150 | 10 | 60 HRC | — |
What is 12KhN3A?
12KhN3A is a GOST nickel-chromium carburizing steel with about 3 % Ni, giving high core toughness for demanding gear and shaft work. It is chosen where impact-loaded cases must sit on a tough core, and is available as hot-rolled, annealed, normalized, cold-drawn, quenched-and-tempered and carburized bar and forgings; the default condition reaches 760 MPa yield, 980 MPa tensile, 13 % elongation and 285 HB (30 HRC). Machinability is modest (score 40) because the Ni-Cr matrix is gummy, weldability is limited (score 40) and the maximum service temperature is 200 °C. For higher core strength in the same alloy system, 20KhN3A is the obvious step up. 12KhN3A 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). 12KhN3A has a yield strength of 760 MPa (110 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 85% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
What is 12KhN3A used for?
- gears
- shafts
- aerospace parts
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High strength — 760 MPa (110 ksi), better than 85% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- High embodied carbon — 2.5 kg CO₂/kg, worse than 82% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
12KhN3A properties
Typical room-temperature values for 12KhN3A-QT; bars are the position among steel grades.
Physical3
12KhN3A 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
12KhN3A has a yield strength of 760 MPa (110 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 85% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
12KhN3A is rated for continuous service to 200°C (392 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 69% of steel grades. Thermal expansion is 11.4 µm/m·K (6.33 µin/in·°F).
Electrical3
12KhN3A conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of 12KhN3A takes about 34 MJ of energy and emits 2.5 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
12KhN3A's machinability is fair (40/100, worse than 77% of steel grades); weldability fair (40/100); formability fair (45/100).
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. 12KhN3A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 12KhN3A
Is 12KhN3A easy to machine?
Machine in the annealed or normalized state (HB ≤ 217) with carbide tooling and generous coolant; the tough Ni-Cr matrix is gummy and work-hardens, so finish grinding is normal after case hardening.
Can 12KhN3A be welded?
Weldable in the low-carbon soft state with 150–250 °C preheat, low-hydrogen consumables and post-weld stress relief; do not weld carburized or hardened zones.
Can 12KhN3A be formed, bent or molded?
Hot forge 1180–850 °C followed by normalizing; cold heading and bending only in the annealed condition with generous bend radii.
12KhN3A 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 | 0.09 – 0.16 | 0.12 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.3 – 0.6 | 0.45 |
| Cr | 0.6 – 0.9 | 0.75 |
| Ni | 2.75 – 3.15 | 2.95 |
| Curesidual | ≤ 0.3 | — |
| Moresidual, not intentionally added | ≤ 0.15 | — |
| S'A' = high-quality, low S/P | ≤ 0.03 | — |
| P'A' = high-quality, low S/P | ≤ 0.03 | — |
| Fe | balance | — |
What surface finishes work on 12KhN3A?
Not anodizable — protect with phosphating, black oxide, oil, zinc or hard chrome; shot peening after carburizing markedly raises bending fatigue of gear roots.
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 12KhN3A in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- GOST
- 12ХН3А
How much does 12KhN3A cost?
12KhN3A 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.
12KhN3A — frequently asked
What is 12KhN3A used for?
12KhN3A is typically used for gears, shafts and aerospace parts. In short: high core toughness; ni-Cr carburizing grade; tougher than Cr-Mn steels.
What is the yield strength of 12KhN3A?
12KhN3A has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 85% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 12KhN3A easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machine in the annealed or normalized state (HB ≤ 217) with carbide tooling and generous coolant; the tough Ni-Cr matrix is gummy and work-hardens, so finish grinding is normal after case hardening.
Can 12KhN3A be welded?
With care — weldability is rated fair (40/100). Weldable in the low-carbon soft state with 150–250 °C preheat, low-hydrogen consumables and post-weld stress relief; do not weld carburized or hardened zones.
What surface finishes work on 12KhN3A?
Not anodizable — protect with phosphating, black oxide, oil, zinc or hard chrome; shot peening after carburizing markedly raises bending fatigue of gear roots.
Can 12KhN3A be formed, bent or molded?
Hot forge 1180–850 °C followed by normalizing; cold heading and bending only in the annealed condition with generous bend radii.
What is the maximum service temperature of 12KhN3A?
12KhN3A 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 12KhN3A-QT and 12KhN3A-A?
QT is the default condition — standard GOST acceptance condition; use for the tough core strength of carburized parts or for through-hardened medium-duty parts. A: softest condition for heavy machining, deep drilling or cold forming before case hardening. Yield strength is 760 MPa in QT versus 380 MPa in A.
How much does 12KhN3A cost?
12KhN3A 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
- GOST 4543-2016 — Alloy structural steel bars — Rosstandart (2016)
- GB/T 3077 — Alloy structural steels (12CrNi3A/12CrNi3) — SAC (2015)
- Marochnik stali i splavov — grade 12ХН3А — Marochnik (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals (carburizing) — ASM International (2013)
- Alloy structural steel bar price levels — Mysteel / 1688 (2025)
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.