Steel 18Kh2N4MA
GOST 18Kh2N4MA (18Х2Н4МА)
18Kh2N4MA (also designated 18Cr2Ni4WA) is a high-alloy Ni-Cr-Mo carburizing steel with roughly 4 % Ni, used for critical heavy-duty aerospace and turbine gearing.
Reference datasheet — 18Kh2N4MA 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 QT200 condition
18Kh2N4MA tempers and conditions
18Kh2N4MA is supplied in 6 conditions, soft to hard. QT200 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Standard machining/delivery condition per GB/T 3077 and GOST 4543 — softest state before carburizing or final quench. | 700 | 900 | 17 | 25 HRC | — |
Hot rolled | As-rolled or as-forged stock; this steel air-hardens, so the bar arrives hard and must be high-temperature tempered before machining. | 850 | 1,150 | 12 | 36 HRC | 4.9 % IACS |
Q&T 500–560 | Choose when a tough, machinable through-hardened part (shafts, fasteners, non-carburized structural sections) is wanted rather than maximum hardness. | 880 | 1,030 | 16 | 32 HRC | — |
Normalized | Grain-refining pre-treatment; because of the high hardenability the normalized bar is still martensitic and needs tempering. | 900 | 1,200 | 12 | 37 HRC | 4.9 % IACS |
QT200Default quenched (950 °C air + 850 °C oil/air) and tempered 200 °C | The condition in which GOST 4543 / GB/T 3077 specify mechanical properties — maximum core strength for gears and shafts. | 980 | 1,250 | 13 | 39 HRC | — |
Carburized | Final service condition for gears and races: hard wear/contact-resistant case over a tough 36–43 HRC Ni-Cr-Mo core. | 980 | 1,250 | 11 | 60 HRC | — |
What is 18Kh2N4MA?
18Kh2N4MA (also designated 18Cr2Ni4WA) is a high-alloy Ni-Cr-Mo carburizing steel with roughly 4 % Ni, used for critical heavy-duty aerospace and turbine gearing. Engineers specify it where both a hard case and a very strong, tough core are required; it is available as hot-rolled, annealed, normalized, quenched-and-tempered (QT200 or QT500) and carburized bar and forgings, with 980 MPa yield, 1250 MPa tensile, 13 % elongation and 363 HB (39 HRC) in the default condition. The trade-offs are low machinability (score 22), poor weldability due to high hardenability, a 200 °C service limit and higher cost than 20KhN3A, which is the nearest lower-alloy substitute. 18Kh2N4MA 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). 18Kh2N4MA has a yield strength of 980 MPa (142 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 91% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
What is 18Kh2N4MA used for?
- Aircraft gears
- Turbine gearbox gearing
- Helicopter transmission shafts
- High-load pinions and ring gears
- Splined power-transmission shafts
- Heavily loaded cams and rollers
- Critical fasteners and pins
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
- Difficult to machine — 22/100, worse than 95% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- High embodied carbon — 2.7 kg CO₂/kg, worse than 89% of steel grades
- Limited formability — 18/100, worse than 84% of steel grades
- Difficult to weld — 22/100, worse than 81% of steel grades
18Kh2N4MA properties
Typical room-temperature values for 18Kh2N4MA-QT200; bars are the position among steel grades.
Physical3
18Kh2N4MA 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).
Mechanical15
18Kh2N4MA has a yield strength of 980 MPa (142 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 91% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18Kh2N4MA is rated for continuous service to 200°C (392 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical2
18Kh2N4MA has an electrical resistivity of 3.5×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of 18Kh2N4MA takes about 36 MJ of energy and emits 2.7 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 25%.
Manufacturability7
18Kh2N4MA's machinability is poor (22/100, worse than 95% of steel grades); weldability poor (22/100); formability poor (18/100).
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. 18Kh2N4MA is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 18Kh2N4MA
Is 18Kh2N4MA easy to machine?
Machine only after high-temperature tempering to ≤269 HB; use rigid setups, coated carbide at moderate speed and heavy positive feed — the 4 % Ni makes the steel gummy and work-hardening.
Can 18Kh2N4MA be welded?
Poor weldability: high hardenability demands 250–350 °C preheat, low-hydrogen or matching filler, and immediate post-weld temper; avoid welding on carburized surfaces.
Can 18Kh2N4MA be formed, bent or molded?
Forge at 1150–850 °C with slow cooling in furnace or ash, then normalize + high-temper; cold forming is impractical beyond minor straightening.
18Kh2N4MA 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 | 0.14 – 0.2 | 0.17 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.25 – 0.55 | 0.4 |
| Cr | 1.35 – 1.65 | 1.5 |
| Ni | 4 – 4.4 | 4.2 |
| MoMo grade 18Kh2N4MA | 0.3 – 0.4 | 0.35 |
| WOnly in the tungsten variant 18Kh2N4VA / GB 18Cr2Ni4WA, which replaces Mo with W | 0.8 – 1.2 | 1 |
| Curesidual | ≤ 0.3 | — |
| Shigh-grade (A) quality | ≤ 0.03 | — |
| Phigh-grade (A) quality | ≤ 0.03 | — |
| Fe | balance | — |
What surface finishes work on 18Kh2N4MA?
Grind the carburized case after heat treatment; protect with oil, phosphate, black oxide or Cd/Zn plating, and bake after plating to avoid hydrogen embrittlement.
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 18Kh2N4MA in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- GOST
- 18Х2Н4МА
- Similar grades
- 18Cr2Ni4WA
How much does 18Kh2N4MA cost?
18Kh2N4MA 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.
18Kh2N4MA — frequently asked
What is 18Kh2N4MA used for?
18Kh2N4MA is typically used for aircraft gears, turbine gearbox gearing, helicopter transmission shafts, high-load pinions and ring gears, splined power-transmission shafts and heavily loaded cams and rollers. In short: strongest core in family; ni-Cr-Mo aerospace gear steel; low machinability, high cost.
What is the yield strength of 18Kh2N4MA?
18Kh2N4MA has a typical yield strength of 980 MPa (142 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 18Kh2N4MA easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of steel grades). Machine only after high-temperature tempering to ≤269 HB; use rigid setups, coated carbide at moderate speed and heavy positive feed — the 4 % Ni makes the steel gummy and work-hardening.
Can 18Kh2N4MA be welded?
Not readily — weldability is rated poor (22/100). Poor weldability: high hardenability demands 250–350 °C preheat, low-hydrogen or matching filler, and immediate post-weld temper; avoid welding on carburized surfaces.
What surface finishes work on 18Kh2N4MA?
Grind the carburized case after heat treatment; protect with oil, phosphate, black oxide or Cd/Zn plating, and bake after plating to avoid hydrogen embrittlement.
Can 18Kh2N4MA be formed, bent or molded?
Forge at 1150–850 °C with slow cooling in furnace or ash, then normalize + high-temper; cold forming is impractical beyond minor straightening.
What is the maximum service temperature of 18Kh2N4MA?
18Kh2N4MA 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 18Kh2N4MA-QT200 and 18Kh2N4MA-A?
QT200 is the default condition — the condition in which GOST 4543 / GB/T 3077 specify mechanical properties — maximum core strength for gears and shafts. A: standard machining/delivery condition per GB/T 3077 and GOST 4543 — softest state before carburizing or final quench. Yield strength is 980 MPa in QT200 versus 700 MPa in A.
How much does 18Kh2N4MA cost?
18Kh2N4MA 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 — Alloyed structural steel bars — Gosstandart (2016)
- GB/T 3077 — Alloy structural steels (18Cr2Ni4WA) (2015)
- Marochnik stali i splavov (Steel and Alloy Grade Handbook) — Mashinostroenie (2003)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing 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.