Steel 20KhN3A-HR (Hot rolled)
Supply condition
GOST 20KhN3A (20ХН3А)
Cheapest mill supply for forging stock or parts that will be fully heat treated later.
Values for the HR condition
Other 20KhN3A tempers and conditions
20KhN3A is listed in 8 conditions; see the grade overview at 20KhN3A.
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 | — |
HRThis page 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-HR?
20KhN3A-HR is 20KhN3A supplied in the HR condition — cheapest mill supply for forging stock or parts that will be fully heat treated later. 20KhN3A-HR has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 67% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi). 20KhN3A-HR 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). Q&T is the default condition FabDigit quotes; HR is available on request or by drawing note.
Limitations
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
20KhN3A-HR properties
Typical room-temperature values for 20KhN3A-HR; 23 are specific to this condition. Other listed values are 20KhN3A reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20KhN3A-HR 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-HR has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 67% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20KhN3A-HR is rated for continuous service to 400°C (752 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical2
20KhN3A-HR 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-HR 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-HR's machinability is fair (48/100, worse than 57% of steel grades); weldability poor (30/100); formability fair (36/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20KhN3A-HR
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.
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.
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 | — |
20KhN3A-HR — frequently asked
What is 20KhN3A-HR used for?
20KhN3A-HR 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-HR?
20KhN3A-HR has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 67% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 20KhN3A-HR easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% 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-HR be welded?
Not readily — weldability is rated poor (30/100). 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-HR?
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-HR 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-HR?
20KhN3A-HR 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.