Steel H12
AISI/SAE H12 · UNS T20812 · GB 4Cr5MoWVSi
H12 is a 5 % Cr-Mo-W-V hot-work die steel (UNS T20812, 1.2606, 4Cr5MoWVSi) in which the tungsten addition provides good hot hardness and mild abrasion resistance at temperature.
Reference datasheet — H12 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN condition
H12 tempers and conditions
H12 is supplied in 7 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
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 |
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?
H12 is a 5 % Cr-Mo-W-V hot-work die steel (UNS T20812, 1.2606, 4Cr5MoWVSi) in which the tungsten addition provides good hot hardness and mild abrasion resistance at temperature. Annealed bar is about 210 HB (760 MPa tensile, 24 % elongation) and the grade is quenched and tempered to roughly 44–52 HRC, with hot-rolled, ESR and nitrided conditions on file. Heat-checking resistance is lower than H13, the steel is not corrosion resistant and the service ceiling is about 500 °C. H13 is the default alternative when thermal fatigue governs die life. H12 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). H12 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 63% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi).
What is H12 used for?
- Extrusion dies
- Die-casting dies
- Hot forging dies
- Mandrels
Advantages
- High service temperature — 500°C (932 °F), better than 90% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Low electrical conductivity — 3.3 % IACS, worse than 86% of steel grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades
- High embodied carbon — 2.5 kg CO₂/kg, worse than 82% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
H12 properties
Typical room-temperature values for H12-ANN; bars are the position among steel grades.
Physical3
H12 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 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 63% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
H12 is rated for continuous service to 500°C (932 °F). It conducts heat at 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
H12 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 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's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (25/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. H12 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with H12
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.
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 |
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.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel H12 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T20812
- GB (China)
- 4Cr5MoWVSi
- Similar grades
- 1.2606
How much does H12 cost?
H12 is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
H12 — frequently asked
What is H12 used for?
H12 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?
H12 has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 63% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is H12 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% 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 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?
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 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?
H12 is rated for continuous use to about 500°C (932 °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.
How much does H12 cost?
H12 is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.