Steel 25Cr2Ni4WA-QT400
Heat-treated state
GB 25Cr2Ni4WA
QT400 = q&T
Pick the 400–450 °C intermediate temper for larger-section transmission parts needing 1350 MPa tensile static strength, trading toughness and machinability against the 550 °C temper.
Values for the QT400 condition
Other 25Cr2Ni4WA tempers and conditions
25Cr2Ni4WA is listed in 8 conditions; see the grade overview at 25Cr2Ni4WA.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Order the GB/T 3077 softened delivery state at ≤269 HB for rough machining and cold straightening before final hardening; yield stays near 700 MPa until quench and temper. | 700 | 880 | 18 | 24 HRC | — |
Hot rolled | Take hot-rolled or as-forged stock only as raw material for subsequent forging and heat treatment; hardness is high at 320 HB and uneven, and machinability is correspondingly poor. | 750 | 1,050 | 13 | 34 HRC | 5.7 % IACS |
Normalized | Use as the preparatory treatment for large-section forgings: normalizing plus tempering refines the structure and lowers residual stress, giving 780 MPa yield, below the quenched and tempered state. | 780 | 950 | 16 | 30 HRC | 5.7 % IACS |
Cold drawn | Pick softened-and-drawn bright bar in small diameters for dimensional accuracy on parts to be finish machined and then fully heat treated; drawing lowers elongation to 10 %. | 850 | 980 | 10 | 30 HRC | 5.7 % IACS |
QT550Default Q&T | Choose the standard 850 °C oil quench plus 550 °C temper for shafts and splines needing 1130 MPa tensile with impact toughness of at least 71 J; machinability falls to a score of 32. | 990 | 1,130 | 13 | 34 HRC | — |
Carburized + quenched & low tempered | Specify carburizing with quench and low temper for landing-gear gears and heavy-duty splines: a 58–62 HRC wear-resistant case over a 1180 MPa tough core, but machinability score is only 6. | 1,000 | 1,180 | 12 | 60 HRC | — |
QT400This page Q&T | Pick the 400–450 °C intermediate temper for larger-section transmission parts needing 1350 MPa tensile static strength, trading toughness and machinability against the 550 °C temper. | 1,150 | 1,350 | 12 | 42 HRC | — |
Q&T | Use the 180–220 °C low temper for small-section, highly stressed parts needing 1550 MPa tensile and wear resistance; toughness drops and hydrogen embrittlement sensitivity rises. | 1,250 | 1,550 | 10 | 47 HRC | — |
What is 25Cr2Ni4WA-QT400?
25Cr2Ni4WA-QT400 is 25Cr2Ni4WA heat treated to QT400 — pick the 400–450 °C intermediate temper for larger-section transmission parts needing 1350 MPa tensile static strength, trading toughness and machinability against the 550 °C temper. 25Cr2Ni4WA-QT400 has a yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,350 MPa (196 ksi) — stronger than 94% of steel grades. Elongation at break is 12% and the elastic modulus is 208 GPa (30.2 Msi). 25Cr2Ni4WA-QT400 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). QT550 is the default condition FabDigit quotes; QT400 is available on request or by drawing note.
Advantages
- High strength — 1,150 MPa (167 ksi), better than 94% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to machine — 22/100, worse than 95% of steel grades
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
- Poor heat conductor — 31 W/m·K (17.9 BTU/hr·ft·°F), worse than 83% of steel grades
25Cr2Ni4WA-QT400 properties
Typical room-temperature values for 25Cr2Ni4WA-QT400; 11 are specific to this condition. Other listed values are 25Cr2Ni4WA reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
25Cr2Ni4WA-QT400 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
25Cr2Ni4WA-QT400 has a yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,350 MPa (196 ksi) — stronger than 94% of steel grades. Elongation at break is 12% and the elastic modulus is 208 GPa (30.2 Msi).
Thermal6
25Cr2Ni4WA-QT400 is rated for continuous service to 280°C (536 °F). It conducts heat at 31 W/m·K (17.9 BTU/hr·ft·°F), worse than 83% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
25Cr2Ni4WA-QT400 conducts electricity at 5.7 % IACS, worse than 80% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of 25Cr2Ni4WA-QT400 takes about 34 MJ of energy and emits 2.6 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
25Cr2Ni4WA-QT400's machinability is poor (22/100, worse than 95% of steel grades); weldability poor (20/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 25Cr2Ni4WA-QT400
Is 25Cr2Ni4WA easy to machine?
High-temperature temper to ≤269 HB before rough machining; after quench and temper or carburizing, finish by grinding only. Cut with coated carbide at low speed and heavier feed with full coolant.
Can 25Cr2Ni4WA be welded?
High carbon equivalent and strong air-hardening tendency make welding unsuitable. If unavoidable, use low-hydrogen procedures with 150–250 °C preheat and post-weld temper, then re-heat-treat the part.
Can 25Cr2Ni4WA be formed, bent or molded?
Hot forge from about 1150 °C down to 850 °C, then cool slowly or high-temperature temper immediately after forging to prevent flakes and cracks. Cold formability is very poor; only light straightening in the annealed state.
What surface finishes work on 25Cr2Ni4WA?
After carburizing and grinding, hard chrome plate for wear or apply cadmium or zinc-flake coating for corrosion protection; bake at 190–200 °C after plating in the high-strength condition to remove hydrogen. The surface can be ground and polished to a mirror finish and shot peened to raise fatigue life.
25Cr2Ni4WA 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 | 0.21 – 0.28 | 0.25 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.25 – 0.55 | 0.4 |
| Cr | 1.35 – 1.65 | 1.5 |
| Ni | 4 – 4.5 | 4.25 |
| W | 0.8 – 1.2 | 1 |
| Curesidual element | ≤ 0.25 | — |
| Phigh-grade quality steel; aerospace parts held lower | ≤ 0.03 | — |
| Shigh-grade quality steel; aerospace parts held lower | ≤ 0.03 | — |
| Fe | balance | — |
25Cr2Ni4WA-QT400 — frequently asked
What is 25Cr2Ni4WA-QT400 used for?
25Cr2Ni4WA-QT400 is typically used for landing gear gears, high-load shafts and carburized aircraft components. In short: carburizing grade of family; hard case, tough core; best for gear teeth.
What is the yield strength of 25Cr2Ni4WA-QT400?
25Cr2Ni4WA-QT400 has a typical yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,350 MPa (196 ksi) — stronger than 94% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 25Cr2Ni4WA-QT400 easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of steel grades). High-temperature temper to ≤269 HB before rough machining; after quench and temper or carburizing, finish by grinding only. Cut with coated carbide at low speed and heavier feed with full coolant.
Can 25Cr2Ni4WA-QT400 be welded?
Not readily — weldability is rated poor (20/100). High carbon equivalent and strong air-hardening tendency make welding unsuitable. If unavoidable, use low-hydrogen procedures with 150–250 °C preheat and post-weld temper, then re-heat-treat the part.
What surface finishes work on 25Cr2Ni4WA-QT400?
After carburizing and grinding, hard chrome plate for wear or apply cadmium or zinc-flake coating for corrosion protection; bake at 190–200 °C after plating in the high-strength condition to remove hydrogen. The surface can be ground and polished to a mirror finish and shot peened to raise fatigue life.
Can 25Cr2Ni4WA-QT400 be formed, bent or molded?
Hot forge from about 1150 °C down to 850 °C, then cool slowly or high-temperature temper immediately after forging to prevent flakes and cracks. Cold formability is very poor; only light straightening in the annealed state.
What is the maximum service temperature of 25Cr2Ni4WA-QT400?
25Cr2Ni4WA-QT400 is rated for continuous use to about 280°C (536 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 25Cr2Ni4WA-QT550 and 25Cr2Ni4WA-A?
QT550 is the default condition — choose the standard 850 °C oil quench plus 550 °C temper for shafts and splines needing 1130 MPa tensile with impact toughness of at least 71 J; machinability falls to a score of 32. A: order the GB/T 3077 softened delivery state at ≤269 HB for rough machining and cold straightening before final hardening; yield stays near 700 MPa until quench and temper. Yield strength is 990 MPa in QT550 versus 700 MPa in A.
Sources
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
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.