Steel 25KhGT QT 28-34HRC
Hardness band
GOST 25KhGT (25ХГТ)
QT 28-34HRC = q&T to 28–34 HRC
Tough through-hardened condition for shafts and cores that will be induction- or nitride-treated later.
Values for the QT 28-34HRC condition
Other 25KhGT tempers and conditions
25KhGT is listed in 7 conditions; see the grade overview at 25KhGT.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard delivery condition of gear-steel bar: softest, best machinability before carburizing. | 400 | 620 | 18 | 197 HB | — |
Normalized | Uniform fine-grain structure and better chip control than annealed; typical pre-carburizing condition for forgings. | 500 | 760 | 15 | 217 HB | — |
Hot rolled | Lowest-cost mill condition for parts that will be fully heat treated after machining. | 520 | 800 | 14 | 20 HRC | 7.5 % IACS |
Cold drawn | Close-tolerance bright bar for automatic-lathe parts and shafts machined near net shape before carburizing. | 700 | 850 | 9 | 24 HRC | 7.5 % IACS |
QT 28-34HRCThis page Q&T to 28–34 HRC | Tough through-hardened condition for shafts and cores that will be induction- or nitride-treated later. | 850 | 1,000 | 13 | 31 HRC | — |
Carburized, quenched & low tempered | The service condition for gears: hard wear-resistant case with a strong, tough 30–40 HRC core. | 980 | 1,180 | 10 | 60 HRC | — |
Q&T | Maximum through-hardened strength for small, non-carburized highly loaded parts (pins, splines). | 1,220 | 1,420 | 9 | 44 HRC | — |
What is 25KhGT QT 28-34HRC?
25KhGT QT 28-34HRC is 25KhGT heat treated to QT 28-34HRC — tough through-hardened condition for shafts and cores that will be induction- or nitride-treated later. 25KhGT QT 28-34HRC has a yield strength of 850 MPa (123 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 88% of steel grades. Elongation at break is 13% and the elastic modulus is 212 GPa (30.7 Msi). 25KhGT QT 28-34HRC has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,425°C (2,597 °F). A is the default condition FabDigit quotes; QT 28-34HRC is available on request or by drawing note.
Advantages
- High strength — 850 MPa (123 ksi), better than 88% of steel grades
Limitations
- Limited ductility — 13%, worse than 78% of steel grades
25KhGT QT 28-34HRC properties
Typical room-temperature values for 25KhGT QT 28-34HRC; 12 are specific to this condition. Other listed values are 25KhGT reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
25KhGT QT 28-34HRC has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
25KhGT QT 28-34HRC has a yield strength of 850 MPa (123 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 88% of steel grades. Elongation at break is 13% and the elastic modulus is 212 GPa (30.7 Msi).
Thermal6
25KhGT QT 28-34HRC is rated for continuous service to 400°C (752 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
25KhGT QT 28-34HRC conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 25KhGT QT 28-34HRC takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
25KhGT QT 28-34HRC's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (30/100); formability fair (48/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 25KhGT QT 28-34HRC
Is 25KhGT easy to machine?
Machine in the annealed/normalized state (≤217 HB) with carbide or coated HSS; leave 0.2–0.4 mm grinding stock on gear teeth for post-carburizing distortion.
Can 25KhGT be welded?
Poor weldability (CE ≈ 0.65): preheat 250–350 °C, low-hydrogen consumables and immediate stress relief; never weld carburized surfaces.
Can 25KhGT be formed, bent or molded?
Hot forge 1150–850 °C then slow-cool or isothermally anneal; cold heading only for small annealed parts due to high Cr-Mn work hardening.
What surface finishes work on 25KhGT?
Gas or vacuum carburize 900–930 °C to 0.8–1.5 mm case, oil quench, temper 180–200 °C, then grind; protect with phosphate + oil, black oxide or zinc plating (bake to avoid H embrittlement).
25KhGT 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 | 0.22 – 0.29 | 0.25 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.8 – 1.1 | 0.95 |
| Cr | 1 – 1.3 | 1.15 |
| Tigrain refiner, allows direct quench after carburizing | 0.03 – 0.09 | 0.06 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| S | ≤ 0.04 | — |
| P | ≤ 0.04 | — |
| Fe | balance | — |
25KhGT QT 28-34HRC — frequently asked
What is 25KhGT QT 28-34HRC used for?
25KhGT QT 28-34HRC is typically used for automotive transmission gears, industrial gearbox gears, splined drive shafts, differential ring and pinion sets, sprockets and gear couplings and carburized pinion shafts. In short: stronger core than 18KhGT; cr-Mn-Ti gear steel; 58-62 HRC case.
What is the yield strength of 25KhGT QT 28-34HRC?
25KhGT QT 28-34HRC has a typical yield strength of 850 MPa (123 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 88% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 25KhGT QT 28-34HRC easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed/normalized state (≤217 HB) with carbide or coated HSS; leave 0.2–0.4 mm grinding stock on gear teeth for post-carburizing distortion.
Can 25KhGT QT 28-34HRC be welded?
Not readily — weldability is rated poor (30/100). Poor weldability (CE ≈ 0.65): preheat 250–350 °C, low-hydrogen consumables and immediate stress relief; never weld carburized surfaces.
What surface finishes work on 25KhGT QT 28-34HRC?
Gas or vacuum carburize 900–930 °C to 0.8–1.5 mm case, oil quench, temper 180–200 °C, then grind; protect with phosphate + oil, black oxide or zinc plating (bake to avoid H embrittlement).
Can 25KhGT QT 28-34HRC be formed, bent or molded?
Hot forge 1150–850 °C then slow-cool or isothermally anneal; cold heading only for small annealed parts due to high Cr-Mn work hardening.
What is the maximum service temperature of 25KhGT QT 28-34HRC?
25KhGT QT 28-34HRC 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 25KhGT-A and 25KhGT-QT200?
A is the default condition — standard delivery condition of gear-steel bar: softest, best machinability before carburizing. QT200: maximum through-hardened strength for small, non-carburized highly loaded parts (pins, splines). Yield strength is 400 MPa in A versus 1,220 MPa in QT200.
Sources
- GOST 4543 — Alloyed structural steel bars — Gosstandart (2016)
- GB/T 3077 (25CrMnTi) — SAC (2015)
- Marochnik Stali — 25ХГТ steel grade data — Marochnik (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals (carburizing) — ASM International (2013)
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.