Steel 12KhN3A-A (Solution annealed)
Temper
GOST 12KhN3A (12ХН3А)
Softest condition for heavy machining, deep drilling or cold forming before case hardening.
Values for the A condition
Other 12KhN3A tempers and conditions
12KhN3A is listed in 8 conditions; see the grade overview at 12KhN3A.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AThis page 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-A?
12KhN3A-A is 12KhN3A in the A temper — softest condition for heavy machining, deep drilling or cold forming before case hardening. 12KhN3A-A has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi). 12KhN3A-A 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). QT is the default condition FabDigit quotes; A is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 70/100, better than 87% 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
12KhN3A-A properties
Typical room-temperature values for 12KhN3A-A; 12 are specific to this condition. Other listed values are 12KhN3A reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
12KhN3A-A 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-A has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
12KhN3A-A 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-A 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-A 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-A's machinability is good (55/100, better than 62% of steel grades); weldability good (55/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 12KhN3A-A
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.
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.
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 | — |
12KhN3A-A — frequently asked
What is 12KhN3A-A used for?
12KhN3A-A 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-A?
12KhN3A-A has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 12KhN3A-A easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% 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-A be welded?
Yes — weldability is rated good (55/100). 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-A?
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-A 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-A?
12KhN3A-A 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.