Steel H25 HT44-46
Hardness band
AISI/SAE H25 · UNS T20825
HT44-46 = hardened & tempered to 44–46 HRC
Choose for large extrusion dies and dummy blocks where thermal fatigue and cracking risk outweigh wear.
Values for the HT44-46 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 |
HT44-46This page 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 | — |
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 HT44-46?
H25 HT44-46 is H25 heat treated to HT44-46 — choose for large extrusion dies and dummy blocks where thermal fatigue and cracking risk outweigh wear. H25 HT44-46 has a yield strength of 1,240 MPa (180 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 94% of steel grades. Elongation at break is 7% and the elastic modulus is 215 GPa (31.2 Msi). H25 HT44-46 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; HT44-46 is available on request or by drawing note.
Advantages
- High service temperature — 620°C (1,148 °F), better than 99% of steel grades
- High strength — 1,240 MPa (180 ksi), better than 94% of steel grades
Limitations
- Difficult to machine — 12/100, worse than 99% of steel grades
- Limited ductility — 7%, worse than 96% of steel grades
- High embodied carbon — 4.2 kg CO₂/kg, worse than 95% of steel grades
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades
H25 HT44-46 properties
Typical room-temperature values for H25 HT44-46; 15 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 HT44-46 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 HT44-46 has a yield strength of 1,240 MPa (180 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 94% of steel grades. Elongation at break is 7% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
H25 HT44-46 is rated for continuous service to 620°C (1,148 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
H25 HT44-46 conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of H25 HT44-46 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 HT44-46's machinability is not recommended (12/100, worse than 99% of steel grades); weldability poor (25/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with H25 HT44-46
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 HT44-46 — frequently asked
What is H25 HT44-46 used for?
H25 HT44-46 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 HT44-46?
H25 HT44-46 has a typical yield strength of 1,240 MPa (180 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 94% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is H25 HT44-46 easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% 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 HT44-46 be welded?
Not readily — weldability is rated poor (25/100). 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 HT44-46?
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 HT44-46 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 HT44-46?
H25 HT44-46 is rated for continuous use to about 620°C (1,148 °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.