H13 Tool Steel
Also: AISI H13, UNS T20813, W.Nr. 1.2344, DIN 1.2344, X40CrMoV5-1, SKD61 (JIS), Böhler W302, Uddeholm Orvar Supreme, H-13, hot work tool steel, H13 ESR, premium H13
H13 is the 5% chromium hot work tool steel for die casting, extrusion and forging dies: tough and heat-check resistant at 44-52 HRC, and often nitrided.
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At a glance
| Density | 7.8 g/cm³ (0.282 lb/in³) |
|---|---|
| Tensile strength | About 1,500-1,600 MPa (220-230 ksi) at 45-46 HRC; about 1,800 MPa (260 ksi) at 50 HRC |
| Yield strength | About 1,300-1,400 MPa (190-200 ksi) at 45-46 HRC; about 1,500 MPa (220 ksi) at 50 HRC |
| Hardness | About 190-230 HB annealed; 44-52 HRC working hardness (44-48 HRC typical for die casting dies) |
| Elongation | About 10-13% at 44-50 HRC |
| Modulus of elasticity | 210 GPa (30.5 Msi) |
| Thermal | Solidus roughly 1,400 °C (2,550 °F); keeps its hardness in service below its tempering temperature of 540-620 °C (1,000-1,150 °F); thermal conductivity about 25 W/m·K |
| Composition | Fe, 0.32-0.45% C, 4.75-5.50% Cr, 1.10-1.75% Mo, 0.80-1.20% V, 0.80-1.20% Si, 0.20-0.50% Mn |
Typical values, Hardened and tempered: gas quench from about 1,010-1,030 °C (1,850-1,885 °F), then a double or triple temper at 540-620 °C (1,000-1,150 °F) to 44-52 HRC. Annealed stock is about 190-230 HB.. Confirm against the mill certificate and the purchase spec.
- MachinabilityGood
- About 75% of the W1 (1% carbon tool steel) benchmark annealed; machines well with carbide. Hardened H13 in the 40s HRC hard mills well with coated carbide, which is how many mold and die cavities are finished.
- WeldabilityFair
- Die repair welding is routine: TIG or laser with an H13-type filler at a preheat of about 315-425 °C (600-800 °F), then a temper about 25 °C (50 °F) below the last one. Welded cold, the heat-affected zone air-hardens and cracks.
- FormabilityPoor
- Forged and machined, not formed. Annealed stock can be straightened; hardened dies cannot be bent.
- Corrosion resistancePoor
- The 5% chromium helps against scaling at die temperatures but does not make it corrosion resistant; water lines rust and idle die faces pit. Nitriding helps against aluminum soldering and erosion.
H13 is a hot work tool steel with about 0.4% carbon, 5% chromium, 1.3% molybdenum and 1% vanadium. It holds its hardness and strength at die surface temperatures that would soften cold work steels, and it resists heat checking, the network of thermal fatigue cracks that forms when a die face cycles between molten metal and a water-cooled, lubricant-sprayed surface. It is the standard steel for aluminum, zinc and magnesium die casting dies and cores, aluminum extrusion dies, hot forging die inserts and high-volume plastic injection molds.
It is bought annealed, rough machined, then hardened with a fast gas quench and tempered two or three times to 44-52 HRC. Die casting dies usually run 44-48 HRC for toughness; extrusion dies, forging inserts and plastic mold cavities run higher, up to about 52 HRC, for wear and polish. Because it is tempered at 540-620 °C (1,000-1,150 °F), it can be nitrided without softening, and a nitrided case is standard on cores, core pins and ejector pins.
Quality matters more with H13 than with most steels. Premium and electroslag remelted (ESR) grades certified to NADCA #207 have the cleanliness and fine, uniform structure that die casting dies need; commodity H13 is fine for punches, fixtures and short-run tooling. At room temperature its wear resistance is well below D2 or A2, and it is not corrosion resistant.
Heat treatment
Preheat in steps (about 650 °C and 845 °C / 1,200 °F and 1,550 °F), austenitize at 1,010-1,030 °C (1,850-1,885 °F), and quench fast, usually in a vacuum furnace with high-pressure gas; NADCA #207 sets a minimum quench rate for die casting dies because a slow quench costs toughness. Temper immediately and at least twice, three times for dies, at 540-620 °C (1,000-1,150 °F). A higher temper means lower hardness: roughly 52 HRC near 565 °C (1,050 °F) and 46-48 HRC near 595 °C (1,100 °F), depending on the hardening temperature and section, so the heat treater tempers to the specified hardness. Anneal at 845-900 °C (1,550-1,650 °F) with a slow cool. Stress temper dies after sampling and periodically in production, about 25-50 °C (50-90 °F) below the last temper.
Tempers and conditions
- Annealed (about 190-230 HB), as stocked
- Hardened and tempered, 44-48 HRC (die casting dies)
- Hardened and tempered, 48-52 HRC (extrusion dies, forging inserts, plastic molds)
- Pre-hardened bar and plate (limited sizes)
- Premium / ESR quality certified to NADCA #207
Stock forms
- Round and flat bar
- Forged die blocks and plate
- Saw-cut blocks
- Precision ground flat stock
- ESR premium-quality blocks
- Powder for metal 3D printing
Relative cost
Tier 3 of 5. Commodity H13 bar is priced near A2 and D2; premium ESR grades certified to NADCA #207 cost noticeably more per pound. On a die casting die, machining, EDM and heat treatment dwarf the steel cost.
Typical applications
- Aluminum, zinc and magnesium die casting dies, cores and slides
- Core pins, ejector pins and sleeves (nitrided)
- Aluminum extrusion dies, mandrels and backers
- Hot forging die inserts and punches
- High-volume plastic injection mold cavities and cores
- Hot shear blades and hot punching tools
Process compatibility
How H13 takes each process, and what to specify. Each process links to its own guide and to the shops that do it.
| Process | Rating | Notes |
|---|---|---|
| CNC Machining | GoodGood | Annealed for roughing; hard milling in the 40s HRC with coated carbide finishes many mold and die cavities after hardening. |
| Sinker EDM | ExcellentExcellent | The standard way to burn ribs, bosses and deep features in hardened die casting and mold cavities; remove the white layer, which starts heat checks. |
| Wire EDM | ExcellentExcellent | Cuts extrusion die openings, slides and inserts in hardened H13; skim-cut the recast layer and temper after heavy cuts. |
| CNC Grinding | GoodGood | Finishes parting lines, shut-offs and ejector pins after hardening. |
| Vacuum Heat Treating | ExcellentExcellent | Vacuum hardening with a high-pressure gas quench is standard for dies; NADCA #207 sets quench rate, hardness and microstructure acceptance. |
| Heat Treating | GoodGood | Commodity tooling can go to a conventional shop with atmosphere control; large die casting dies belong in a vacuum furnace with a fast quench. |
| Nitriding | ExcellentExcellent | Gas, plasma or salt-bath nitriding adds a hard case of roughly 0.1-0.2 mm against erosion, soldering and wear, with no core softening because H13 is tempered above the nitriding temperature. Can H13 tool steel be nitrided? |
| Stress Relieving | GoodGood | Stress temper after die trials and periodically in production, 25-50 °C below the last temper, to extend die life. |
| Shot Peening | GoodGood | Peening die faces and cores puts the surface in compression and delays heat checking. |
| Welding | FairFair | Routine die repair with a 315-425 °C (600-800 °F) preheat and a post-weld temper. |
| Hard Chrome Plating | FairFair | Used on plastic mold cavities for release and corrosion; bake for hydrogen. Die casting dies use nitriding or PVD instead. |
| Forging | GoodGood | Mills and forge shops hot forge die blocks; forged and ESR blocks have more uniform properties than rolled plate for large dies. |
| Metal 3D Printing | FairFair | Printable by laser powder bed fusion for conformal-cooled inserts, but crack-prone during the build; many shops print maraging steel instead. Heat treat and finish-machine after printing. |
| Carburizing | Not recommendedNot recommended | A carburized case on H13 is brittle and heat-checks and spalls in hot work; nitriding is the surface treatment for this steel. |
Design and sourcing tips
- Specify the quality and the hardness: "H13 premium quality to NADCA #207, 44-46 HRC" for a die casting die; commodity H13 is fine for punches, fixtures and short-run tools.
- Radius every internal corner, avoid abrupt section changes and keep cooling lines well back from the cavity face; heat checks and cracks start at sharp corners and thin walls over water lines.
- Call for nitriding with a case depth, for example 0.1-0.2 mm (0.004-0.008"), on cores, core pins and ejector pins, and nitride after final machining and polishing.
- Plan stress tempers: after sampling and periodically in production, a temper 25-50 °C (50-90 °F) below the last one extends die life.
- For mirror-polished plastic mold cavities, ask for ESR stock; inclusions in commodity bar polish out as pits.
- Leave finish stock for grinding or EDM after hardening; large blocks move in the fast quench that die casting dies need.
Frequently asked questions
- What is H13 tool steel used for?
- Tools that work hot: die casting dies, cores and core pins for aluminum, zinc and magnesium; aluminum extrusion dies; hot forging die inserts and punches. It is also a common steel for high-volume plastic injection molds, where its toughness, polishability and response to nitriding matter more than its hot hardness.
- Can H13 be welded?
- Yes; repair welding of H13 dies is routine. Preheat to about 315-425 °C (600-800 °F), weld by TIG or laser with an H13-type filler, keep the part hot through the weld, cool slowly and temper about 25 °C (50 °F) below the last tempering temperature. Welding cold or skipping the temper leaves an untempered, crack-prone heat-affected zone that heat-checks early.
- Why is H13 nitrided?
- Nitriding diffuses nitrogen into the surface and forms a hard case, typically 0.1-0.2 mm deep on dies, that resists erosion, washout, aluminum soldering and wear while the core keeps its toughness. It works on H13 because the nitriding temperature, about 500-540 °C (930-1,000 °F), is at or below its tempering temperature, so the core does not soften.
- What hardness should an H13 die casting die be?
- Most aluminum die casting dies run 44-48 HRC. Large dies sit at the low end for toughness against gross cracking; small cores, inserts and zinc dies can run higher for wear and heat-check resistance. Extrusion dies, forging inserts and plastic molds usually run 48-52 HRC. NADCA #207 gives the acceptance criteria die casters and heat treaters work to.
- H13 vs P20 for injection molds?
- P20 is supplied pre-hardened, around 28-32 HRC, and is machined to finish with no heat treatment, so it is cheaper and faster for low and medium volumes of unfilled resins. H13 is hardened to 48-52 HRC after roughing, which costs time and money, but it wears far longer, takes a better polish, resists glass-filled resins and can be nitrided. Choose H13 for high volumes, abrasive resins and cavities that must stay polished.
Processes that commonly use it
Related materials
Where to verify these values
- ASTM A681 (chemistry and annealed hardness limits)
- NADCA #207, Special Quality Die Steel and Heat Treatment Acceptance Criteria for Die Casting Dies
- Producer data sheets: Böhler W302, Uddeholm Orvar Supreme (H13 / 1.2344)
- ASM Handbook Vol. 4, Heat Treating (tool steel hardening and tempering)
