Steel H12-QT44
Heat-treated state
AISI/SAE H12 · UNS T20812 · GB 4Cr5MoWVSi
QT44 = hardened & tempered to 44–46 HRC
Choose for large forging dies and extrusion tooling where thermal-fatigue cracking, not wear, governs life.
Values for the QT44 condition
Other H12 tempers and conditions
H12 is listed in 7 conditions; see the grade overview at H12.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ESR (electroslag remelted) premium quality, annealed | Specify for large die blocks and polished cavities needing low inclusion content, tighter isotropy and better transverse toughness. | 495 | 750 | 26 | 205 HB | 3.3 % IACS |
ANNDefault Annealed | Standard mill supply condition for bar and plate; machine the die cavity here, then harden and temper. | 500 | 760 | 24 | 210 HB | — |
Hot rolled | Low-cost oversize stock for roughing; must be annealed or hardened before use — hardness and structure are non-uniform. | 800 | 1,000 | 12 | 32 HRC | 28 W/m·K |
QT44This page Hardened & tempered to 44–46 HRC | Choose for large forging dies and extrusion tooling where thermal-fatigue cracking, not wear, governs life. | 1,250 | 1,450 | 11 | 45 HRC | 27 W/m·K |
Hardened, tempered + gas/plasma nitrided case | Surface treatment for extrusion dies and die-casting inserts to resist soldering and abrasion; keep the case thin to avoid heat-check initiation. | 1,300 | 1,560 | 9 | 48 HRC | 3.2 % IACS |
Hardened & tempered to 47–49 HRC | Balanced hardness/toughness setting used for most hot-forging, die-casting and extrusion tooling. | 1,400 | 1,600 | 9 | 48 HRC | 27 W/m·K |
Hardened & tempered to 51–54 HRC | Use for punches, dummy blocks and mandrels where abrasion at temperature dominates and shock loads are low. | 1,600 | 1,850 | 6 | 53 HRC | — |
What is H12-QT44?
H12-QT44 is H12 heat treated to QT44 — choose for large forging dies and extrusion tooling where thermal-fatigue cracking, not wear, governs life. H12-QT44 has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 95% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi). H12-QT44 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). ANN is the default condition FabDigit quotes; QT44 is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- High service temperature — 560°C (1,040 °F), better than 96% of steel grades
- High strength — 1,250 MPa (181 ksi), better than 95% of steel grades
Limitations
- Difficult to machine — 25/100, worse than 93% of steel grades
- Limited ductility — 11%, worse than 89% of steel grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades
- Low electrical conductivity — 3.3 % IACS, worse than 86% of steel grades
- High embodied carbon — 2.5 kg CO₂/kg, worse than 82% of steel grades
H12-QT44 properties
Typical room-temperature values for H12-QT44; 17 are specific to this condition. Other listed values are H12 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
H12-QT44 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).
Mechanical15
H12-QT44 has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 95% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
H12-QT44 is rated for continuous service to 560°C (1,040 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
H12-QT44 conducts electricity at 3.3 % IACS, worse than 86% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of H12-QT44 takes about 33 MJ of energy and emits 2.5 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 40%.
Manufacturability8
H12-QT44's machinability is poor (25/100, worse than 93% of steel grades); weldability poor (25/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with H12-QT44
Is H12 easy to machine?
Machine fully in the annealed condition (≈60 % of 1212) with rigid setups and coated carbide; above ~45 HRC use hard-milling or EDM plus stress relief.
Can H12 be welded?
Weldable for die repair only: preheat/interpass 350–400 °C, matching 5 % Cr filler, slow cool and immediately re-temper 15–20 °C below the last tempering temperature.
Can H12 be formed, bent or molded?
Hot work at 1050–1120 °C with slow cooling to 850 °C and immediate annealing at 845–900 °C; cold forming is not practical.
What surface finishes work on H12?
Takes a good mirror polish (best in ESR quality); protect with nitriding, PVD (CrN/AlTiN), phosphating or oil — do not anodize, and avoid decarburized skin before polishing.
H12 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 |
|---|---|---|
| CASTM A681 / GB/T 1299 4Cr5MoWVSi | 0.3 – 0.4 | 0.35 |
| Si | 0.8 – 1.2 | 1 |
| Mn | 0.2 – 0.5 | 0.35 |
| Cr | 4.75 – 5.5 | 5.1 |
| Mo | 1.25 – 1.75 | 1.5 |
| Wdistinguishes H12 from H13 | 1 – 1.7 | 1.4 |
| V | 0.2 – 0.5 | 0.4 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
H12-QT44 — frequently asked
What is H12-QT44 used for?
H12-QT44 is typically used for extrusion dies, die-casting dies, hot forging dies and mandrels. In short: tungsten-bearing 5 % Cr grade; good hot hardness; reduced heat-check resistance.
What is the yield strength of H12-QT44?
H12-QT44 has a typical yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is H12-QT44 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Machine fully in the annealed condition (≈60 % of 1212) with rigid setups and coated carbide; above ~45 HRC use hard-milling or EDM plus stress relief.
Can H12-QT44 be welded?
Not readily — weldability is rated poor (25/100). Weldable for die repair only: preheat/interpass 350–400 °C, matching 5 % Cr filler, slow cool and immediately re-temper 15–20 °C below the last tempering temperature.
What surface finishes work on H12-QT44?
Takes a good mirror polish (best in ESR quality); protect with nitriding, PVD (CrN/AlTiN), phosphating or oil — do not anodize, and avoid decarburized skin before polishing.
Can H12-QT44 be formed, bent or molded?
Hot work at 1050–1120 °C with slow cooling to 850 °C and immediate annealing at 845–900 °C; cold forming is not practical.
What is the maximum service temperature of H12-QT44?
H12-QT44 is rated for continuous use to about 560°C (1,040 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between H12-ANN and H12-QT52?
ANN is the default condition — standard mill supply condition for bar and plate; machine the die cavity here, then harden and temper. QT52: use for punches, dummy blocks and mandrels where abrasion at temperature dominates and shock loads are low. Yield strength is 500 MPa in ANN versus 1,600 MPa in QT52.
Sources
- ASTM A681 Standard Specification for Tool Steels Alloy — ASTM International (2022)
- GB/T 1299 (4Cr5MoWVSi) — SAC (2014)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- Tool Steels, 5th ed. — ASM International (1998)
- Hot-work tool steel datasheets (5 % Cr class, W-alloyed) — Böhler / voestalpine (2022)
- (H12/4Cr5MoWVSi ) (2025)
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.