English Views: 0 Author: Eternal Tech Team Publish Time: 2026-09-30 Origin: Site
If you work in die casting, hot forging, or extrusion, you have almost certainly encountered H13 tool steel. It is the workhorse of hot-work tooling — the material that endures molten aluminum at 700 °C, the hammering of a forging press, and the relentless thermal cycling of high-pressure die casting (HPDC). At our forging facility, H13 mold steel is the single material we forge most — and for good reason.
H13 is a chromium-molybdenum-vanadium hot-work tool steel classified under the AISI/SAE designation system. It is defined by ASTM A681, the standard specification for tool steels, where it appears as Type H13 (UNS T20813). In DIN/EN standards, it is known as 1.2344; in JIS, SKD61; and in GB, 4Cr5MoSiV1.
What sets H13 apart from other tool steels is its balanced combination of hot hardness, thermal fatigue resistance, and toughness — the three properties that matter most when a tool must survive repeated contact with hot metal. H13 is the most widely used hot-work tool steel globally, surpassing H11, H21, and other grades in both consumption and application breadth.
From a forging perspective, H13's chemistry is specifically designed to respond well to hot working. The chromium content provides hardenability and high-temperature strength; molybdenum contributes to hot hardness and reduces temper embrittlement; vanadium forms stable carbides that resist grain growth and improve wear resistance; and the medium carbon level (0.32–0.45%) delivers the hardness necessary for die surfaces without sacrificing toughness in the core.
The chemical composition of H13 tool steel is tightly specified. According to the latest ASTM A681-2024 standard, the ranges are as follows:
Element | ASTM A681 Range (wt.%) | Role |
Carbon (C) | 0.32 – 0.45 | Hardness, carbide formation |
Chromium (Cr) | 4.75 – 5.50 | Hardenability, hot strength, wear resistance |
Molybdenum (Mo) | 1.10 – 1.75 | Hot hardness, temper resistance |
Vanadium (V) | 0.80 – 1.20 | Grain refinement, wear resistance, secondary hardening |
Silicon (Si) | 0.80 – 1.25 | Tempering resistance |
Manganese (Mn) | 0.20 – 0.60 | Deoxidation, hot workability |
Phosphorus (P) | ≤ 0.030 | Impurity control |
Sulfur (S) | ≤ 0.030 | Impurity control |
For premium die-casting applications, the North American Die Casting Association (NADCA) specifies tighter sulfur limits: ≤ 0.005% for premium grade and ≤ 0.003% for superior grade H13. Lower sulfur improves toughness and reduces the risk of heat checking — a critical factor for dies that operate under high thermal gradients.
At our facility, we forge H13 from steel ingots that have undergone secondary refining — typically ESR (Electroslag Remelting) or VAR (Vacuum Arc Remelting). These processes reduce non-metallic inclusions and gas content, producing cleaner steel with better fatigue performance. Research shows that VIM+VAR H13 achieves fatigue strength of approximately 1040 MPa at 10⁷ cycles, compared to 967 MPa for ESR steel, due to a mean inclusion size roughly 55% smaller. Forging then refines the cast microstructure, closes internal porosity, and aligns the flow lines to the shape of the die — yielding isotropic mechanical properties that cast-and-rolled material cannot match.
The engineering value of H13 lies in four core properties.
H13 maintains useful hardness at elevated temperatures — typically up to 540–600 °C in continuous service. When tempered at 550 °C, it exhibits a secondary hardening peak with hardness reaching approximately 600 HV (~55 HRC), due to the precipitation of fine vanadium-rich carbides. This means H13 dies do not soften prematurely even under the continuous heat load of aluminum die casting.
Thermal fatigue cracking — commonly called “heat checking” — is the dominant failure mode for die-casting dies. H13's chromium and silicon content provides resistance to thermal shock and thermal cycling, allowing it to endure hundreds of thousands of casting cycles before crack networks become critical.
Despite its high hardness, H13 retains excellent fracture toughness. Typical mechanical properties for properly heat-treated H13 include:
Property | Typical Value |
Hardness (quenched) | ~55 HRC |
Tensile strength (46 HRC) | ~1,503 MPa |
Tensile strength (51 HRC) | ~1,937 MPa |
Yield strength | 1,400 – 1,468 MPa |
Elongation | 5 – 8% |
Values represent conventionally heat-treated H13; additive-manufactured variants can reach UTS above 1,900 MPa
Vanadium carbides in H13 provide abrasion resistance against the erosive action of molten metal and the sliding wear of extrusion billets. For extrusion dies and hot shear blades, this translates directly into longer tool life.
Heat treatment is where H13 either performs brilliantly or fails early. The standard sequence is preheating → austenitizing → quenching → double tempering. Here are the recommended parameters based on industry practice and Jiangyin Eternal Heavy Industry Co.,Ltd’s recommendations for premium H13.
Preheat in two stages to prevent thermal shock and distortion:
Stage 1: Raise to 650 °C (1,200 °F) and equalize.
Stage 2: Raise to 850 °C (1,550 °F) and equalize.
For large blocks (cross-section > 150 mm), an intermediate step at 800–900 °C is recommended.
Temperature: 1,020–1,050 °C (1,870–1,920 °F); typically 1,030 °C (1,885 °F).
Holding time: Minimum 30 minutes after the part is fully heated, or 20 minutes for the first 25 mm of thickness plus 15 minutes per additional 25 mm.
Do not exceed 1,050 °C — higher temperatures cause grain growth and reduce toughness.
Vacuum furnace with positive-pressure inert gas is the preferred method for minimal distortion.
Oil quenching is acceptable for simpler shapes.
Minimum cooling rate: 28 °C/min (50 °F/min) measured at ~16 mm depth to suppress pearlite formation.
Quench until the part reaches approximately 65 °C (150 °F) — do not quench to room temperature.
Always double temper. Temper immediately after quenching, while the part is still at approximately 65 °C. Typical tempering parameters:
Tempering Temperature | Resulting Hardness |
550 °C (1,020 °F) | 48–52 HRC |
565 °C (1,050 °F) | 46–50 HRC |
580 °C (1,080 °F) | 44–48 HRC |
600 °C (1,110 °F) | 42–46 HRC |
Hold time: minimum 2 hours at temperature, or 1 hour per inch of wall thickness
For die-casting dies, the recommended working hardness range is typically 44–48 HRC, balancing thermal fatigue resistance against wear and cracking resistance.
Deep cryogenic treatment at −196 °C after conventional hardening converts retained austenite to martensite and promotes fine carbide precipitation. Studies show that cryogenically treated H13 exhibits twice the wear resistance of conventionally treated material, due to the formation of fine tertiary carbides. For dies expected to run millions of cycles, this step is well worth considering.
If you are sourcing H13 tool steel internationally, you will encounter different grade names. Here is the definitive cross-reference:
Standard | Grade Designation |
AISI/SAE (USA) | H13 (UNS T20813) |
ASTM A681 (USA) | A681 Type H13 |
DIN/EN (Germany) | 1.2344 |
JIS (Japan) | SKD61 |
GB (China) | 4Cr5MoSiV1 |
ISO | 40CrMoV5 |
AFNOR (France) | Z40CDV5 |
Important note for purchasers: While these grades are “equivalent,” they are not identical. The carbon range for AISI H13 per ASTM is 0.32–0.45%, whereas JIS SKD61 is typically 0.32–0.42%, and GB 4Cr5MoSiV1 is 0.32–0.42%. For critical die-casting applications, always specify the exact standard and supplementary requirements (e.g., ESR, NADCA compliant, sulfur ≤ 0.005%).
H13's property profile makes it the default choice for a broad range of hot-work tooling:
Aluminum die casting dies and inserts — the largest single application. H13 resists thermal fatigue and erosion from molten aluminum at 650–700 °C.
Zinc and magnesium die casting dies — lower-temperature but high-cycle applications where H13's toughness and wear resistance extend die life.
Hot forging dies and inserts — hammer dies, press dies, and upsetter dies for steel and non-ferrous forging.
Aluminum extrusion dies — both solid and hollow profile dies, where H13's hot hardness resists the deformation and wear of pushing billet through the die.
Hot shear blades and trimming tools — used at elevated temperatures where conventional tool steel would soften.
Plastic injection molds — particularly for engineering plastics processed at high melt temperatures.
Plunger tips, shot sleeves, and sprue bushings in die-casting machines.
At our forging shop, we routinely forge H13 blocks and bars for die-casting customers who require large cross-sections with uniform properties. Forging to near-net shape reduces machining allowance and ensures the deformation flow lines follow the die contour — a significant advantage for thermal fatigue life compared to cut-from-plate material.
The global H13 supply chain includes major mills in the US, Europe, Japan, and China, as well as specialized forging houses. When evaluating an H13 tool steel supplier, consider these criteria:
Melting method — ESR or VAR refined material is essential for die-casting and high-cycle forging dies. Air-melted H13 has higher inclusion content and reduced fatigue life.
Forging capability — If you need large blocks or custom-shaped die blanks, a supplier with in-house forging can control microstructure and mechanical properties more precisely than a pure stockholder.
NADCA compliance — For aluminum die casting, specify H13 that meets NADCA 207 requirements, including sulfur and phosphorus limits and cleanliness ratings.
Heat treatment services — Some suppliers offer pre-hardened H13 in the 37–41 HRC range for plastic molds and short-run die casting, reducing your in-house processing steps.
Traceability — Full documentation of heat number, melting method, chemical analysis, and ultrasonic inspection.
Chinese supplier such as Jiangyin Eternal Heavy Industry Co.,Ltd is active in the H13 forging market, with annual capacities several thousand tons. Our facility focuses specifically on forged H13 mold steel blocks and bars with ESR/VAR feedstock, serving die-casting and forging customers who require premium material performance.
Q: What is the hardness of H13 tool steel after heat treatment?
A: Quenched H13 reaches approximately 55 HRC. After tempering, the typical working hardness for die-casting dies is 44–48 HRC, achieved by tempering at 580–600 °C. For applications requiring higher wear resistance but lower toughness demand, 48–52 HRC is achievable with tempering at 550 °C.
Q: Can H13 tool steel be welded?
A: Yes, but weldability is limited. Preheating to 300–400 °C and using matching H13 filler metal are essential. Post-weld tempering is required. For critical die repairs, use a laser or TIG welding process with controlled heat input to minimize the heat-affected zone.
Q: Is H13 tool steel corrosion resistant?
A: No. H13 is not a stainless steel. Its chromium content (~5%) is far below the ~12% minimum for corrosion resistance. For applications requiring corrosion resistance, consider a stainless mold steel such as S136 (420 stainless) or apply a surface treatment (nitriding, PVD coating).
Q: What is the difference between H13 and H11 tool steel?
A: H11 (1.2343) has lower chromium (3.0–3.5%) and vanadium (0.3–0.6%) than H13 (Cr: 4.75–5.5%, V: 0.8–1.2%). H13 offers better wear resistance and hot hardness; H11 provides slightly better toughness. H13 is the more widely used grade for general hot-work applications.
Q: How long does an H13 die-casting die last?
A: With proper heat treatment (44–48 HRC) and maintenance (periodic stress relief, surface nitriding), H13 aluminum die-casting dies typically achieve 100,000 to 500,000+ shots. Premium ESR/VAR H13 with optimized heat treatment can exceed 1 million cycles in favorable operating conditions.
Q: What is the difference between H13 and 1.2344?
A: They are essentially the same material under different standards. H13 is the AISI/ASTM designation; 1.2344 is the DIN/EN Werkstoff number. The chemistry is nearly identical, though individual mill specifications may vary slightly. When purchasing, always specify the standard (ASTM A681 or DIN 1.2344) and any supplementary requirements.
Q: Can H13 be used for cold-work applications?
A: While H13 is classified as a hot-work steel, its high hardness and wear resistance allow limited use in cold-work applications such as cold forging punches, shear blades, and even plastic molds. However, for high-volume cold work, D2 or M2 tool steels are generally more cost-effective.
Q: What is the best heat treatment for maximum die life in aluminum die casting?
A: The industry consensus is austenitize at 1,025–1,030 °C, vacuum or positive-pressure gas quench, and double temper at 580–600 °C for a final hardness of 44–48 HRC. This hardness range optimizes the balance between thermal fatigue resistance (which favors lower hardness) and wear/erosion resistance (which favors higher hardness).
H13 tool steel is not a commodity. The difference between a die that lasts 200,000 shots and one that fails at 50,000 often comes down to the quality of the starting material and the forging process. ESR/VAR melting reduces inclusions that initiate fatigue cracks. Forging refines the cast structure and creates directional flow lines that follow the die contour. Proper heat treatment unlocks the secondary hardening response that gives H13 its hot strength.
At our forging facility, we do one thing well: forge H13 mold steel for customers who cannot afford premature die failure. Whether you need a 5-ton die block for a large HPDC machine or a custom-shaped forging die blank, we combine premium feedstock, controlled forging parameters, and metallurgical expertise to deliver H13 that performs.
