H13 Tool Steel | 1.2344 | SKD61 - AoboSteel

Author: Vic

Aug. 25, 2025

H13 Tool Steel | 1. | SKD61 - AoboSteel

H13 tool steel is an air-hardening hot work tool steel and is one of the most widely used steels among all hot work tool steels. Similar to D2 tool steel as a benchmark for cold work tool steels, H13 is the benchmark for hot work tool steels. Compared to H11 tool steel, this steel grade has higher thermal strength and hardness. It can be air-hardened, so it performs well in terms of quenching deformation and residual stress, and has a lower likelihood of surface oxidation. Additionally, it can achieve secondary hardening, has excellent thermal stability, and can effectively resist corrosion from aluminum alloy molten metal.

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Manufacturers widely use this steel grade to produce hot extrusion dies and mandrels, drop hammer forging dies, and forging dies. It is also commonly used for inserts in precision forging machines and die-casting dies for aluminum, copper, and their alloys.

The designation in the U.S. ASTM A681 system is H13, and the name in the American AISI system is AISI H13 steel. Similarly, other national standards use comparable designations, such as ISO 40CrMoV5, Japan/JIS SKD61, USA/UNS T, Germany/DIN X40CrMoV5-1, Germany/W-Nr. 1., and Czech Republic (CSN) , BS (BH13), SS (), ANFOR (Z40CDV5), UNI (X35CrMoV05KU / X40CrMoV511KU), and China GB/T (4Cr5MoSiV1)

1. Applications

  • Hot Work Tooling: It is a primary choice for most hot-working operations, especially when dies require cooling with water or other flushing media.
  • Die Casting Molds: H13 material is particularly suitable for die casting zinc, aluminum, and magnesium alloys, such as push rods, ejector pins, core pins, slides, nozzles, and sprues. H13 material blocks purified by electroslag remelting (ESR) are suitable for plastic molds that require a high surface finish, such as automotive lens molds, due to their higher purity and uniformity.
  • Hot Forging Dies and Punches
  • Hot Extrusion Dies: Hot extrusion of light metals such as aluminum and magnesium, as well as for mandrels, punches, and dies.
  • Plastic Injection Molds: This is the most common application, especially for machining cavities.
  • Shearing Blades: Hot shearing applications.
  • Friction Stir Welding (FSW) Tools : FSW tools, particularly for welding aluminum plates, are often coated with TiN for enhanced performance.
  • Structural Components: H13 steel has high strength and can maintain its hardness at high temperatures, so it is used in structural components that are subject to high stress, such as aircraft landing gear, arrester hooks, and rocket shells in the aerospace industry.

 2. H13 Steel Composition

H13 tool steel equivalent grades’ composition

3. H13 tool steel properties

H13 mold steel is a hot-work tool steel widely used globally. It is characterized by high strength, high toughness, high hardenability, and resistance to thermal cracking. In particular, it can maintain its strength and hardness at high temperatures. Additionally, it has excellent comprehensive mechanical properties and high tempering stability.

3.1 Mechanical Properties

The specific properties depend heavily on the tempering temperature. Here are typical longitudinal mechanical properties when air-cooled from °C ( °F) and tempered:

Key Mechanical Properties (Typical Values at Room Temperature, Double Tempered 2h + 2h)

3.2 Physical properties

3.3 Other Important Properties:

  • Wear Resistance: Excellent wear resistance. To further improve wear resistance, it can be nitrided, which can increase its surface hardness to over HV (>70 HRC).
  • Toughness & Impact Strength: Excellent impact strength and good ductility.
  • Heat Checking Resistance: Excellent resistance to thermal cracking, and this characteristic is influenced by its unnotched impact toughness and hardness.
  • Fatigue Resistance: Good fatigue resistance, and in this respect, this steel has an advantage over  alloy steel.
  • Dimensional Stability: When this steel undergoes air quenching, its volume typically expands by approximately 0.001 in./in. (0.001 mm/mm).
  • Machinability: If the machinability rating of carbon steel with a carbon content of 1% is set to 100, then H13 has a machinability rating of 70 when properly annealed.

4. Heat Treatment

The H13 steel heat treatment involves several critical steps to achieve the desired properties:

4.1 Forging and Post-Forging Cooling

It is easy to forge and is typically forged at temperatures between  and °C ( to °F). Before forging, we recommend preheating the steel to 790 to 815°C ( to °F), then uniformly heating it to the required forging temperature.

During forging, the material temperature must not drop below 925°C (°F). If it is about to fall below this temperature, it must be reheated to the required forging temperature.

This material is an air-hardening steel that must be cooled slowly to prevent stress cracking. After forging, the material must be placed in a furnace at 790°C (°F) and held until the temperature is uniform; then cooled slowly.

4.2 Annealing (Spheroidize Anneal)

Following the previous step, the H13 material should undergo spheroidizing annealing, which aims to eliminate stress, enhance the toughness and ductility, and form the required microstructure.

The specific details of the annealing process are as follows: heat the steel to 871°C (°F), hold for 1 hour per inch (25.4 mm) of thickness, then cool at a rate of 14°C (25°F) per hour down to 482°C (900°F), followed by air cooling to room temperature.

4.3 Normalizing (Generally Not Recommended)

Because of the risk of cracking, we generally do not recommend normalizing treatment for H13, especially when a controlled atmosphere furnace does not prevent surface decarburization. However, this normalizing treatment can still improve the uniformity of the material. This step must be performed immediately after spheroidizing annealing.
The specific steps are as follows: preheat to approximately 790 °C ( °F), slowly and uniformly heat to to °C ( to °F), hold for 1 hour per 25 mm (1 inch) of thickness, and then air cool.

4.4 Hardening (Austenitizing and Quenching)

The hardening temperature is around  °C ( °F). Other sources suggest a range of - °C (- °F), or specifically °C ( °F).

H13 is an air-hardening steel, and we recommend performing a preheating treatment. The purpose is to stabilize the crystalline structure, reduce hardness, increase ductility, improve machinability, promote uniform grain structure, and minimize distortion/cracking. The preheating temperature is 815 °C ( °F). For a 1” (25mm) cube, it should be preheated to 650 °C ( °F) and held for 10 to 15 minutes before setting the furnace for the soaking step. For delicate parts, an additional preheat may be necessary.

After preheating, raise the furnace temperature to its austenitizing temperature of  °C ( °F). The soaking process then begins, with the soaking time calculated from the moment the material’s temperature is the same as the furnace temperature. Specific details are as follows: For parts thicker than 1“ (25mm), the soak time is typically half an hour per inch of the smallest cross-section. For smaller parts, specific soak times are provided: 1/8” (3.175mm) for 10-15 minutes, 1/4” (6.350mm) for 15 minutes, 1/2“ (12.70mm) for 20 minutes, 3/4” (19.05mm) for 25-30 minutes, and 1” (25mm) for 30 minutes.

Air quenching can minimize residual stress and reduce thermal shock. While air quenching is the most common method for H13, oil quenching is also used in practice, but it increases internal stresses. The hardness after quenching is 52-54 HRC. During the quenching cycle of the material, the next step of tempering should be performed immediately at a temperature no lower than 66°C/150°F to prevent cracking.

4.5 Tempering

The purpose is to reduce brittleness, transform martensite into a more stable microstructure, improve toughness, relieve stresses while retaining hardness.

We recommend tempering H13 twice or even three times to achieve optimal toughness and extend tool life. The first tempering temperature is 565°C (°F), the second tempering temperature is 550°C (°F), with each cycle lasting 2 hours per inch (25mm) of thickness.

After tempering, the hardness varies with the tempering temperature. For example, as-quenched H13 has a hardness of 52-54 HRC. Tempering at 204°C (400°F) results in 51-53 HRC, while tempering at 538°C (°F) yields 47-48 HRC, and at 621°C (°F), it can be 36-38 HRC. Typical tempering temperatures range from 540-620°C (-°F), producing a stable microstructure that makes the material most suitable for high-temperature applications.

It is essential to avoid tempering H13 at around 500°C (930°F), as this temperature yields the lowest toughness.

5. Welding

H13 steel is readily weldable, especially for repair applications in molds, tools, and dies. Gas Tungsten Arc Welding (GTAW or TIG) is the most suitable welding process for H13 molds, tools, and dies, and can also be performed using an inert gas process or coated electrodes. When welding, the minimum recommended arc voltage and current must be used, and the electrode must be moved slowly in a straight line to minimize heat input. Clean slag frequently and peen the welds while they are still hot (above 370°C or 700°F); never peen a cold weld.

  1. Preheating. Preheating is essential before welding H13 steel, as cold welding can easily cause cracking. The preheating temperature should be between 110°C (230°F) and 375°C (707°F).
  2. Filler Wire. H13 filler wire is the preferred choice. If H13 filler wire is not available on site, a general-purpose medium-hardness tool steel filler wire designed specifically for thermal and cold working tools can be used.
  3. Shielding Gas. Argon is the standard welding gas for TIG welding H13, and it protects the weld seam from contamination. Hydrogen can be used as a backing shielding gas for the underside of the weld when an explosion risk is not present.
  4. Post-Welding Treatment for H13 Tool Steel. After welding, H13 welded parts (especially thick-walled welded parts) should be cooled slowly, either in a furnace at the preheating temperature or using an insulating medium (such as furnace slag, lime, mica, or diatomaceous earth). After slow cooling, the weld should undergo complete spheroidizing annealing.

6. H13 Steel Advantages and Disadvantages

6.1 Advantages

  • Excellent Toughness and Impact Strength
  • High Wear Resistance. H13’s relatively high vanadium content makes it very resistant to abrasion. This is because vanadium promotes the formation of very hard, stable carbides (like V8C7, MC type), which significantly increase wear resistance. Nitriding treatment can further improve the wear resistance of H13.
  • Excellent Hot Hardness, Temper Resistance, and Thermal Stability
  • High Hardenability and Dimensional Stability
  • Good Resistance to Heat Checking (Thermal Fatigue)
  • Weldability and Machinability. H13 is readily weldable, and after appropriate annealing treatment, it has good machinability

6.2 Disadvantages

  • High-cost. H13 tool steel is generally limited by its high cost. The high content of alloying elements contributes to this cost. Of course, this is only a relative disadvantage. Our customers in China have a very high demand for H13 steel, exceeding 2,000 tons per month, mainly for aluminum profiles.
  • Fabrication and Processing Difficulties. The heat treatment process for H13 during production may be relatively complex, which is mainly a challenge for manufacturers. Additionally, its machinability is more difficult compared to low-alloy materials. As mentioned earlier in the article, the good machinability of H13 is one of its advantages, so both advantages and disadvantages are relative.
  • Toughness and Brittleness Issues. It is quite sensitive to quench embrittlement, where precipitation of carbides along prior-austenite grain boundaries can significantly reduce toughness by creating paths for crack propagation, especially for large-section materials.
  • Susceptibility to Cracking and Distortion. Improper quenching processes, insufficient tempering time, or low tempering temperatures can all increase the risk of cracking and deformation.
  • Limited High-Temperature Performance. Although H13 is a hot-work steel, its strength decreases at temperatures above 650°C.

7. Compare with other steels

7.1 Compared to D2 tool steel

H13 steel is used in high-temperature conditions, where it exhibits excellent resistance to softening, thermal fatigue, and impact. Compared to cold-worked steel, however, it has lower wear resistance. D2 steel, on the other hand, performs exceptionally well in cold-working applications, offering high wear resistance and excellent dimensional stability. Compared to H13, however, D2 has lower toughness and poorer performance in high-temperature conditions.

Here is a side-by-side comparison highlighting their key differences and similarities:

7.2 Compared to M2 tool steel

M2 tool steel is primarily used for high-speed cutting, boasting excellent wear resistance and thermal hardness.

8. Supply forms and dimensions

The H13 tool steel we supply is available in three shapes: flat bar, block, and round bar. The dimensions of the flat bar range from: width 20–600 mm × thickness 20–400 mm × length 1,000–5,500 mm. The dimensions of the round bar range from a diameter of 20–400 mm × a length of 1,000–5,500 mm. The block dimensions are obtained by cutting the flat bar.

For smaller sizes, such as round bars with a diameter less than 70 mm, we use the hot-rolled process. For sizes greater than 70 mm, we offer forged products.

We also offer the ESR (Electroslag Remelting) process, which is tailored to meet customer requirements. The advantage is better internal microstructure, but it comes at a higher cost. Please contact us for specific requirements.

UT testing: Sep -84 D/d, E/e. 

Surface Treatment: original black, peeled, machined/turned, polished, grounded, or milled surface finishes.

Inventory Status: We do not maintain a stock of H13 tool steel. We arrange production based on customer orders.

Delivery time: Electric Arc Furnace (EAF) materials are 30-45 days. ESR materials are approximately 60 days. 

Many of our customers choose non-ESR processes when considering cost-effectiveness. Please discuss your specific requirements with us directly.

For more 718h steelinformation, please contact us. We will provide professional answers.

FAQ

Our Products

H13 Tool Steel: Properties, Applications, and Machining ...

AISI H13 is a versatile alloy. It is preferred for applications like hot forging, die casting and extrusion. These require high-temperature steel and die steel. It is widely employed in injection molding and die casting production. More information about the properties, applications, benefits and limitations of AISI H13 is discussed in this article.

What is H13 Steel?

H13 steel also refers as DIN 1. is chromium-molybdenum based hot work steel. it is known as high-temperature steel and die steel due to high temperature and abrasion resistance. high hot hardness increases its thermal fatigue cracking resistance and is preferred for tooling applications

Key Characteristics

The key features of DIN 1. are as follows:

  • Known as hot work steel, die steel and high-temperature steel.
  • High abrasion resistance under low and high temperatures conditions.
  • Higher toughness and malleability
  • High machinability and polishing feature
  • Better high temperature and thermal cracking resistance.
  • High thermal conductivity and hot cracking resistance
  • H13 material HRC hardness is high
  • Less distortion in work hardening

Best Cutting Tools for H13

Cutting tools are of different grades based on their chemical composition, mechanical and physical properties. ideal tool steels for machining are O1, M2, D2 and A2. Other important aspects are speed levels. Inappropriate tool selection could reduce the hardness and wear resistance with time. Therefore, it is best to manufacture tool with high-speed steel. The cost of cutting tool is also important to ensure material is suitable enough to result the required performance.

H13 Steel Equivalent Materials

The equivalent grades of AISI H13 steel are:

Cost

AISI H13 cost depends on many factors like market rate, suppliers, form of hot work steel, size, quality and processing requirement. The rough estimate of DIN1. is around $-/metric ton.

Pros and Cons of H13 Mold Steel

The pros of AISI H13 or SKD 61 high temperature steel are as:

  • Maintains a good balance between toughness and H13 material HRC hardness.
  • Survive high temperature while maintaining its strength and hardness
  • High thermal cycling fatigue resistance suitable for applications as hot work steel.
  • Good machinability to make intricate and complex shapes.
  • Wear resistance is excellent because of high hardness
  • Has many applications such as hot work steel, die steel and high temperature steel.

Along with these advantages, there are few limitations in the application of DIN 1. steel which are as:

  • Corrosion resistance is moderate and harsh corrosive agents can affect the performance of tool or die made of AISI H13.
  • Can be costly with other high-temperature steel.
  • Specific and precise heat treatments in high-temperature steel. are required to attain desired properties which makes it costly.
  • Weldability is limited and cracking can occur in welds in high-temperature steel.

H13 Tool Steel Applications

  • Injection molds and dies

AISI H13 steel is used to manufacture injection molds and die-casting because of high h13 material HRC hardness. It is employed in flip cap molds. Other industries also prefer this because of high toughness and wear resistance.

  • Extrusion dies

SKD61 has high thermal properties. This makes it perfect for extrusion dies. Extrusion mandrels and cores are also made of AISI H13 due to high heat resistance.

  • Hot forging dies

High thermal properties make it useful in hot forging applications. It is also employed in making dies, inserts and other parts requires in hot forging applications.

  • Pressure casting dies

SKD61 is mostly employed as tooling steel for Aluminum pressure die casting. It is best for hot gripper dies and hot nut tools.

  • Other high-temperature tooling

There are also other applications of DIN 1. steel in the production of plastic molds. This material is favorable in applications like die holder blocks, hot press dies and hot work punches.

The Composition and Properties of H13 Material

Chemical composition of AISI H13 material is as:

Detailed chemical composition

The table include the chemical composition of AISI H13.

How alloying elements influence performance

Major alloying elements in SKD61 steel are chromium, vanadium and molybdenum. Cr increases the H13 material HRC hardness of and its toughness. It also increases the corrosion resistance in high temperature steel. Mo increases the hardenability, toughness and strength in DIN 1. steel. vanadium increases the yield and tensile strength in steels.

The preparation process of H13 tool and die steels manipulated by trace nanoparticles: (a) melt, (b) addition and release of nanoparticles, (c) uniform distribution of nanoparticles, (d) casting, (e) steel ingot

Density

The density of AISI H13 at 20℃ is 7.8g/cm3.

Mechanical properties

The mechanical properties of SKD61 are as follows:

Heat Treatment of H13 Steel

Importance of proper heat treatment

AISI H13 are heat treated to get high performance in terms of high strength, hardness and high impact resistance and toughness.

Hardening H13 Tool Steel

AISI H13 is pre-heated to 816℃ and then temperature is rose up to ℃. Holding time is 15-40 mins which is then air-quenched to harden the H13 tool steel.

Tempering H13 Tool Steel

Tempering is normally in the range 550-621℃ in SKD61. The hardness at different tempering temperatures is as follows:

Annealing

AISI H13 is annealed to ᵒF and then furnace cooled to 900ᵒF at 30ᵒ/hour. Then the material is air cooled.

Recommended temperatures and durations

Recommended temperature for SKD61 heat treatment is 800-℃. The duration to hold the material is around 15-40 mins to get optimum properties.

Achieving optimal hardness and toughness

Depending on the temperature cooling rate and holding time, optimum hardness and toughness can be achieved in SKD61.

Machining AISI H13 Tool Steel

Tips for Successful Machining

Hardness is greatest of concern in SKD61 machining. Carbide tools with coating are recommended to use. Coolant like water soluble coolants help to dissipate heat while machining. Pre and post treatments mat be necessary such as surface finishing or heat treatment.

Challenges and considerations

Challenges in DIN 1. tool steel machining are its high hardness and toughness and high heat generation. It is necessary to select an appropriate cutting tool, cutting parameters like speed levels and using coolant to dissipate generate heat.

On the correlation between processing parameters, plastic deformation, and mechanical property in hard machining of H13 steel.

Welding

Welding of SKD61 has limitations. Welds are prone to cracking and therefore, preheating is necessary to maintain suitable interpass temperature. Post welding treatment can reduce the residual stress and cracking risk.

Tuofa China expertise in H13 machining

Tuofa CNC machining specializes in tool steel CNC machining. Tuofa offers high-quality steel products to meet the desired criteria of your project. We are specialized in cutting tools, forming tools, injection molding and die steel. Our expertise ensures the right material selection for your project.  For more information, please visit: https://www.tuofa-cncmachining.com/

Advanced Topic: Comparison with other Stainless Steels

H11 vs H13 Steel

H11 has less vanadium than DIN 1.. H11 has higher toughness but less wear resistance and tempering resistance.

H13 Steel vs

H13 has high hardness and heat resistance. has high toughness.

H13 Steel vs P20

DIN 1. is suitable for molds and for high-production volume. P20 is more suitable for low production volume of molds and is less costly.

H13 vs. D2

D2 has higher hardness than DIN 1. and is better tool steel.

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