Steel 20KhN3A
GOST 20KhN3A (20ХН3А)
20KhN3A is the higher-carbon version of the GOST Ni-Cr carburizing steels, offering greater core strength than 12KhN3A for heavily loaded gears and shafts.
Reference datasheet — 20KhN3A 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 Q&T condition
20KhN3A tempers and conditions
20KhN3A is supplied in 8 conditions, soft to hard. Q&T 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 | Pick for maximum machinability and best condition before carburizing of complex gear blanks. | 430 | 700 | 21 | 197 HB | — |
Hot rolled | Cheapest mill supply for forging stock or parts that will be fully heat treated later. | 520 | 820 | 16 | 22 HRC | 6.2 % IACS |
Normalized and tempered | Use when a stress-relieved, easily machined but stronger-than-annealed blank is wanted. | 560 | 780 | 19 | 19 HRC | 6.3 % IACS |
Normalized | Grain-refining condition used to homogenize forgings before carburizing or final Q&T. | 620 | 900 | 16 | 26 HRC | 6.2 % IACS |
Q&TDefault Quenched and tempered | Standard through-hardened condition quoted in GOST 4543 — best all-round core strength/toughness for shafts and gear cores. | 780 | 980 | 14 | 31 HRC | — |
Cold drawn | Choose for close-tolerance bright bar and small turned parts where no further hot heat treatment is planned. | 780 | 950 | 10 | 28 HRC | 6.1 % IACS |
Carburized and hardened | The intended service condition: hard wear-resistant case with tough high-strength core for heavily loaded gears and splines. | 950 | 1,200 | 11 | 60 HRC | — |
Oil quenched + low temper 180–250 °C | Highest core strength/hardness for pins, small shafts and fasteners where toughness demand is moderate. | 1,100 | 1,350 | 10 | 42 HRC | — |
What is 20KhN3A?
20KhN3A is the higher-carbon version of the GOST Ni-Cr carburizing steels, offering greater core strength than 12KhN3A for heavily loaded gears and shafts. It is supplied hot-rolled, annealed, normalized, normalized-and-tempered, quenched-and-tempered, cold-drawn or case-hardened; the default condition gives 780 MPa yield, 980 MPa tensile, 14 % elongation and 300 HB (31 HRC), with a maximum service temperature of 400 °C. Weldability is poor (CE approximately 0.7) and machinability is low (score 42), so parts are usually machined soft and ground after carburizing. Where core toughness matters more than core strength, use 12KhN3A. 20KhN3A 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). 20KhN3A has a yield strength of 780 MPa (113 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 86% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
What is 20KhN3A used for?
- Heavy-duty gears
- Gearbox and pinion shafts
- Ring gears and bevel pinions
- Splined and keyed drive shafts
- Crown wheels for axle drives
- Cams and gear-type couplings
- High-load piston pins
Advantages
- High strength — 780 MPa (113 ksi), better than 86% of steel grades
Limitations
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
20KhN3A properties
Typical room-temperature values for 20KhN3A-Q&T; bars are the position among steel grades.
Physical3
20KhN3A 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
20KhN3A has a yield strength of 780 MPa (113 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 86% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20KhN3A is rated for continuous service to 400°C (752 °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).
Electrical2
20KhN3A has an electrical resistivity of 2.8×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of 20KhN3A takes about 34 MJ of energy and emits 2.6 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
20KhN3A's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (28/100); formability poor (30/100).
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. 20KhN3A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 20KhN3A
Is 20KhN3A easy to machine?
Machine in the annealed/normalized state (≈180–230 HB) with coated carbide, moderate speed and rigid setups; leave 0.3–0.6 mm stock for post-carburizing grinding since the case cannot be turned.
Can 20KhN3A be welded?
Poor weldability — CE ≈ 0.7; if unavoidable use low-hydrogen electrodes, 250–350 °C preheat, interpass control and immediate 550–650 °C post-weld temper; never weld after carburizing.
Can 20KhN3A be formed, bent or molded?
Hot forge 1180–850 °C with slow cooling and a subsequent normalize/anneal; cold forming limited to light straightening or thread rolling in the annealed condition.
20KhN3A 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 | 0.17 – 0.24 | 0.2 |
| 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 |
| Shigh-quality grade ('A') restriction | ≤ 0.03 | 0.01 |
| Phigh-quality grade ('A') restriction | ≤ 0.03 | 0.01 |
| Curesidual | ≤ 0.3 | 0.15 |
| Moresidual, not intentionally added | ≤ 0.15 | 0.05 |
| Fe | balance | — |
What surface finishes work on 20KhN3A?
No anodizing (ferrous); protect with oil, manganese phosphate, black oxide, zinc or hard chrome plating — bake after plating to avoid hydrogen embrittlement in high-strength conditions; case-hardened surfaces are finish-ground and can be shot peened for fatigue.
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 20KhN3A in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- GOST
- 20ХН3А
How much does 20KhN3A cost?
20KhN3A 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.
20KhN3A — frequently asked
What is 20KhN3A used for?
20KhN3A is typically used for heavy-duty gears, gearbox and pinion shafts, ring gears and bevel pinions, splined and keyed drive shafts, crown wheels for axle drives and cams and gear-type couplings. In short: higher core strength; ni-Cr heavy gear steel; 400 C service limit.
What is the yield strength of 20KhN3A?
20KhN3A has a typical yield strength of 780 MPa (113 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 20KhN3A easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine in the annealed/normalized state (≈180–230 HB) with coated carbide, moderate speed and rigid setups; leave 0.3–0.6 mm stock for post-carburizing grinding since the case cannot be turned.
Can 20KhN3A be welded?
Not readily — weldability is rated poor (28/100). Poor weldability — CE ≈ 0.7; if unavoidable use low-hydrogen electrodes, 250–350 °C preheat, interpass control and immediate 550–650 °C post-weld temper; never weld after carburizing.
What surface finishes work on 20KhN3A?
No anodizing (ferrous); protect with oil, manganese phosphate, black oxide, zinc or hard chrome plating — bake after plating to avoid hydrogen embrittlement in high-strength conditions; case-hardened surfaces are finish-ground and can be shot peened for fatigue.
Can 20KhN3A be formed, bent or molded?
Hot forge 1180–850 °C with slow cooling and a subsequent normalize/anneal; cold forming limited to light straightening or thread rolling in the annealed condition.
What is the maximum service temperature of 20KhN3A?
20KhN3A 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 20KhN3A Q&T and 20KhN3A-A?
Q&T is the default condition — standard through-hardened condition quoted in GOST 4543 — best all-round core strength/toughness for shafts and gear cores. A: pick for maximum machinability and best condition before carburizing of complex gear blanks. Yield strength is 780 MPa in Q&T versus 430 MPa in A.
How much does 20KhN3A cost?
20KhN3A 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, technical requirements — Gosstandart / Rosstandart (2016)
- Marochnik stalei i splavov (Steel and Alloy Grades Handbook) — Mashinostroenie (2003)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 4A — Steel Heat Treating Fundamentals and Processes (carburizing) — ASM International (2013)
- GB/T 3077 — Alloy structural steels (20CrNi3 comparable grade) — SAC (2015)
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.