Steel H25-AQ (As-quenched)
Heat-treated state
AISI/SAE H25 · UNS T20825
Intermediate state only — must be tempered immediately; brittle and contains retained austenite.
Values for the AQ condition
Other H25 tempers and conditions
H25 is listed in 6 conditions; see the grade overview at H25.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard mill supply condition for bar and forgings; machine dies here, then harden and temper. | 430 | 760 | 20 | 217 HB | — |
Hot rolled | Mill stock before soft annealing — order only if you will re-anneal and rough-machine in house. | 800 | 1,000 | 12 | 31 HRC | 2.9 % IACS |
Hardened & tempered to 44–46 HRC | Choose for large extrusion dies and dummy blocks where thermal fatigue and cracking risk outweigh wear. | 1,240 | 1,450 | 7 | 45 HRC | — |
Hardened & tempered to 46–48 HRC | The usual delivered working hardness for hot punches, mandrels and brass die-casting tooling. | 1,330 | 1,550 | 6 | 47 HRC | — |
Hardened & tempered to 50–52 HRC | Use where hot wear and red hardness govern — short-run extrusion tooling, hot shear blades — accepting minimal toughness. | 1,500 | 1,750 | 3 | 51 HRC | — |
AQThis page As-quenched | Intermediate state only — must be tempered immediately; brittle and contains retained austenite. | 1,600 | 1,960 | 1 | 55 HRC | 2.7 % IACS |
What is H25-AQ?
H25-AQ is H25 heat treated to AQ — intermediate state only — must be tempered immediately; brittle and contains retained austenite. H25-AQ has a yield strength of 1,600 MPa (232 ksi) and a tensile strength of 1,960 MPa (284 ksi) — stronger than 98% of steel grades. Elongation at break is 1% and the elastic modulus is 213 GPa (30.9 Msi). H25-AQ has a density of 8.55 g/cm³ (0.309 lb/in³), heavier than 99% of steel grades. It melts at 1,400°C (2,552 °F). ANN is the default condition FabDigit quotes; AQ is available on request or by drawing note.
Advantages
- High strength — 1,600 MPa (232 ksi), better than 98% of steel grades
Limitations
- Difficult to machine — 5/100, worse than 100% of steel grades
- Difficult to weld — 5/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
- Limited ductility — 1%, worse than 99% of steel grades
- Low electrical conductivity — 2.7 % IACS, worse than 96% of steel grades
H25-AQ properties
Typical room-temperature values for H25-AQ; 23 are specific to this condition. Other listed values are H25 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
H25-AQ has a density of 8.55 g/cm³ (0.309 lb/in³), heavier than 99% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
H25-AQ has a yield strength of 1,600 MPa (232 ksi) and a tensile strength of 1,960 MPa (284 ksi) — stronger than 98% of steel grades. Elongation at break is 1% and the elastic modulus is 213 GPa (30.9 Msi).
Thermal6
H25-AQ is rated for continuous service to 200°C (392 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
H25-AQ conducts electricity at 2.7 % IACS, worse than 96% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of H25-AQ takes about 62 MJ of energy and emits 4.2 kg of CO₂ — more than 96% of steel grades. Typical recycled content is 40%.
Manufacturability8
H25-AQ's machinability is not recommended (5/100, worse than 100% of steel grades); weldability not recommended (5/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with H25-AQ
Is H25 easy to machine?
Machine only in the annealed condition with rigid setups, positive-rake carbide or coated carbide at low-to-moderate speed; the 15 % W gives abrasive carbides that wear HSS tooling quickly — hardened parts need grinding or EDM.
Can H25 be welded?
Repair-weld with matching or H-type filler after preheat to 400–500 °C, keep interpass hot, and temper immediately below the last tempering temperature; cold welding causes cracking.
Can H25 be formed, bent or molded?
Hot-work only — forge from ~1120–1150 °C, finish above 900 °C and slow-cool/anneal at 870–900 °C; no practical cold forming.
What surface finishes work on H25?
Stress-relieve after rough machining; nitride or PVD-coat working faces for die-wash and wear resistance, oil or phosphate for storage — no anodizing, and coarse tungsten carbides limit mirror polish.
H25 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 – 0.32 | 0.25 |
| Mn | 0.15 – 0.4 | 0.3 |
| Si | 0.15 – 0.4 | 0.3 |
| Cr | 3.75 – 4.5 | 4 |
| Wprincipal hot-hardness carbide former | 14 – 16 | 15 |
| V | 0.4 – 0.6 | 0.5 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
H25-AQ — frequently asked
What is H25-AQ used for?
H25-AQ is typically used for hot extrusion dies, hot forging dies, die-casting inserts for high-temp alloys and hot punches. In short: high red hardness; strength over toughness; tougher option is H21.
What is the yield strength of H25-AQ?
H25-AQ has a typical yield strength of 1,600 MPa (232 ksi) and a tensile strength of 1,960 MPa (284 ksi) — stronger than 98% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is H25-AQ easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of steel grades). Machine only in the annealed condition with rigid setups, positive-rake carbide or coated carbide at low-to-moderate speed; the 15 % W gives abrasive carbides that wear HSS tooling quickly — hardened parts need grinding or EDM.
Can H25-AQ be welded?
Not readily — weldability is rated not recommended (5/100). Repair-weld with matching or H-type filler after preheat to 400–500 °C, keep interpass hot, and temper immediately below the last tempering temperature; cold welding causes cracking.
What surface finishes work on H25-AQ?
Stress-relieve after rough machining; nitride or PVD-coat working faces for die-wash and wear resistance, oil or phosphate for storage — no anodizing, and coarse tungsten carbides limit mirror polish.
Can H25-AQ be formed, bent or molded?
Hot-work only — forge from ~1120–1150 °C, finish above 900 °C and slow-cool/anneal at 870–900 °C; no practical cold forming.
What is the maximum service temperature of H25-AQ?
H25-AQ 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 H25-ANN and H25-AQ?
ANN is the default condition — standard mill supply condition for bar and forgings; machine dies here, then harden and temper. AQ: intermediate state only — must be tempered immediately; brittle and contains retained austenite. Yield strength is 430 MPa in ANN versus 1,600 MPa in AQ.
Sources
- ASTM A681 — Standard Specification for Tool Steels, Alloy — ASTM International (2015)
- SAE J437/J438 — Tool and Die Steels — SAE International (2015)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Hot-Work Tool Steels) — ASM International (1990)
- ASM Handbook Vol. 4: Heat Treating (Tool Steel Heat Treatment) — ASM International (1991)
- ASM Handbook Vol. 16: Machining — ASM International (1989)
- Tool Steels, 5th ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- GB/T 1299 (2014)
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.