Steel 18KhGT-A (Solution annealed)
Temper
GOST 18KhGT (18ХГТ)
Pick when heavy hobbing, broaching or cold forming of blanks is required before carburizing.
Values for the A condition
Other 18KhGT tempers and conditions
18KhGT is listed in 7 conditions; see the grade overview at 18KhGT.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AThis page Solution annealed | Pick when heavy hobbing, broaching or cold forming of blanks is required before carburizing. | 400 | 640 | 23 | 170 HB | — |
HRDefault Hot rolled | Standard mill delivery condition for bar/forging stock — machine, then carburize and harden. | 500 | 760 | 18 | 197 HB | — |
Normalized | Use to homogenize forgings and refine grain before carburizing or final machining. | 560 | 820 | 16 | 18 HRC | 7.8 % IACS |
Cold drawn | Choose for small-diameter shafts and pins needing close tolerance and good surface before case hardening. | 700 | 850 | 9 | 22 HRC | 7.7 % IACS |
case 58–63 HRC, shallow case | Choose for thin-section, lightly loaded gears and small shafts where a shallow, low-distortion, wear-resistant case is enough. | 970 | 1,150 | 10 | 60 HRC | 7.5 % IACS |
Quenched (860–880 °C, oil) + tempered 200 °C | The GOST 4543 property-verification condition; also used for small through-hardened parts not needing a carburized case. | 980 | 1,150 | 11 | 38 HRC | — |
Carburized + quenched + tempered | The service condition for gears, splines and pinions: hard wear-resistant case on a tough core; grind after treatment. | 1,000 | 1,200 | 9 | 60 HRC | — |
What is 18KhGT-A?
18KhGT-A is 18KhGT in the A temper — pick when heavy hobbing, broaching or cold forming of blanks is required before carburizing. 18KhGT-A has a yield strength of 400 MPa (58 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 60% of steel grades. Elongation at break is 23% and the elastic modulus is 210 GPa (30.5 Msi). 18KhGT-A has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). HR is the default condition FabDigit quotes; A is available on request or by drawing note.
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
18KhGT-A properties
Typical room-temperature values for 18KhGT-A; 10 are specific to this condition. Other listed values are 18KhGT reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
18KhGT-A has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical13
18KhGT-A has a yield strength of 400 MPa (58 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 60% of steel grades. Elongation at break is 23% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18KhGT-A is rated for continuous service to 350°C (662 °F). It conducts heat at 41 W/m·K (23.7 BTU/hr·ft·°F), worse than 62% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
18KhGT-A conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 18KhGT-A takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
18KhGT-A's machinability is good (62/100, better than 89% of steel grades); weldability fair (40/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 18KhGT-A
Is 18KhGT easy to machine?
Machine soft (≤217 HB, ideally isothermally annealed) with carbide at moderate speeds; after carburizing only grinding/EDM is practical, so leave 0.1–0.3 mm grind stock.
Can 18KhGT be welded?
Weldable only before case hardening — preheat 200–300 °C, low-hydrogen filler, post-weld temper; welding a carburized surface causes cracking.
Can 18KhGT be formed, bent or molded?
Excellent hot forgeability at 1150–1200 °C (stop ≥850 °C) followed by normalizing; cold forming limited, best done in the annealed state.
What surface finishes work on 18KhGT?
Not corrosion resistant — protect with oil, manganese/zinc phosphate, black oxide, or Zn/Ni plating (bake to avoid hydrogen embrittlement on hardened parts); shot peening boosts gear-tooth fatigue life.
18KhGT 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 – 0.23 | 0.2 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.8 – 1.1 | 0.95 |
| Cr | 1 – 1.3 | 1.15 |
| Tigrain-refining addition; GB/T 3077 20CrMnTi specifies 0.04–0.10 | 0.03 – 0.09 | 0.06 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| S | ≤ 0.04 | — |
| P | ≤ 0.04 | — |
| Fe | balance | — |
18KhGT-A — frequently asked
What is 18KhGT-A used for?
18KhGT-A is typically used for automotive transmission gears, gearbox shafts, differential ring gears and pinions, splined shafts, synchronizer hubs and sprockets. In short: standard automotive gear steel; titanium-refined fine grain; nickel-free carburizing grade.
What is the yield strength of 18KhGT-A?
18KhGT-A has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 18KhGT-A easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machine soft (≤217 HB, ideally isothermally annealed) with carbide at moderate speeds; after carburizing only grinding/EDM is practical, so leave 0.1–0.3 mm grind stock.
Can 18KhGT-A be welded?
With care — weldability is rated fair (40/100). Weldable only before case hardening — preheat 200–300 °C, low-hydrogen filler, post-weld temper; welding a carburized surface causes cracking.
What surface finishes work on 18KhGT-A?
Not corrosion resistant — protect with oil, manganese/zinc phosphate, black oxide, or Zn/Ni plating (bake to avoid hydrogen embrittlement on hardened parts); shot peening boosts gear-tooth fatigue life.
Can 18KhGT-A be formed, bent or molded?
Excellent hot forgeability at 1150–1200 °C (stop ≥850 °C) followed by normalizing; cold forming limited, best done in the annealed state.
What is the maximum service temperature of 18KhGT-A?
18KhGT-A is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 18KhGT-HR and 18KhGT CARB58?
HR is the default condition — standard mill delivery condition for bar/forging stock — machine, then carburize and harden. CARB58: the service condition for gears, splines and pinions: hard wear-resistant case on a tough core; grind after treatment. Yield strength is 500 MPa in HR versus 1,000 MPa in CARB58.
Sources
- GOST 4543-2016 Alloy structural steels — grades (18ХГТ) — Rosstandart (2016)
- GB/T 3077-2015 (20CrMnTi) — SAC/China (2015)
- Marochnik steel grade database — 18ХГТ — Marochnik (2023)
- ASM Handbook Vol.1: Properties and Selection — Carburizing Steels — ASM International (1990)
- ASM Handbook Vol.4: Heat Treating (carburizing, case depth and hardness) — ASM International (1991)
- 20CrMnTi / — Mysteel / 1688 (2026)
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.