H13 Steel Technical Overview

H13 Steel Technical Overview: Here is the information about H13 steel you are looking for. H13 tool steel is an air-cooled hardening hot work die steel. It is widely used in high-temperature and high-load applications such as die-casting molds, hot rolling, and hot forging tools due to its excellent heat, wear, and thermal fatigue resistance. After heat treatment, it can obtain good comprehensive mechanical properties and high temper resistance.

1. H13 steel chemical composition

Carbon (C)	Chromium (Cr)	Molybdenum (Mo)	Vanadium (V)	Silicon (Si)	Iron (Fe)	Nickel (Ni)	Copper (Cu)	Manganese (Mn)
0.32 – 0.45	4.75 – 5.50	1.10 – 1.75	0.80 – 1.20	0.80 – 1.20	≥ 90.9	≤ 0.3	≤ 0.25	Smaller amounts

2. H13 steel mechanical property

Typical room-temperature longitudinal mechanical properties of H13 steel

Tempering Temperature (°C)	Tempering Temperature (°F)	Tensile Strength (MPa)	Tensile Strength (ksi)	Yield Strength (MPa)	Yield Strength (ksi)	Elongation in 4D (%)	Reduction in Area (%)	Charpy V-Notch Impact Energy (J)	Charpy V-Notch Impact Energy (ft-lbf)	Hardness (HRC)
527	980	1960	284	1570	228	13	46.2	16	12	52
555	1030	1835	266	1530	222	13.1	50.1	24	18	50
575	1065	1730	251	1470	213	13.5	52.4	27	20	48
593	1100	1580	229	1365	198	14.4	53.7	28.5	21	46
605	1120	1495	217	1290	187	15.4	54	30	22	44

Source: ASM Handbook, Volume 4: Heat Treating

3. Applications

Based on the characteristics of H13 tool steel, its applications are primarily in areas that leverage its high hot strength, toughness, wear resistance, and resistance to thermal fatigue.

3.1 Die Casting Dies: H13 is extensively used to manufacture die casting dies. This includes dies for:

• • Aluminum alloys.
  • Magnesium alloys.
  • Zinc alloys.
  • Copper alloys. Its resistance to thermal shock and cracking caused by the rapid heating and cooling cycles in die casting makes it a preferred material.

3.2 Hot Forging Dies: Due to its high strength and toughness at elevated temperatures, H13 is well-suited for hot forging dies, including machine forging dies.

3.3 Hot Extrusion Dies: H13’s hot strength and wear resistance make it suitable for hot extrusion processes, including dies for aluminum profiles.

3.4 Warm Extrusion Dies: H13 can also be used for warm extrusion applications.

3.5 Plastic Molds: While primarily a hot work steel, certain grades or pre-hardened conditions of H13 (or similar steels) find use in plastic molding, particularly for:

• Thermoplastic molds.
• Thermosetting plastic molds.
• Complex cavity molds. The toughness and machinability (especially in pre-hardened conditions) benefit these applications.

3.6 Mold Bases: H13 (or its equivalent SKD61) can be used for mold bases where strength and stability are required.

3.7 Precision Hot Work Components: Due to its properties, H13 can be used for high-precision hot work accessories and nozzles, especially those working with zinc and aluminum alloys for extended periods.

3.8 Rolling Dies: In the bearing industry, H11 and H13 are used to manufacture rolling dies, offering improved lifespan.

The common thread across these applications is the need for a material that can withstand high temperatures and stresses while maintaining its integrity and resisting wear and cracking. The specific heat treatment applied to H13, as we discussed previously, is crucial in tailoring its properties for these diverse uses.

4. H13 steel heat treatment

Please note that specific parameters can vary based on the final application and the size of the components.

Here’s a general outline of the H13 heat treatment process:

• Preheating: Typically, H13 steel undergoes a preheating stage. The preheat temperature is 1500°F (815°C). This mitigates thermal shock during the upper temperature austenitizing stage. It’s generally advisable to refer to the manufacturer’s recommendations for the appropriate preheating process for the particular steel involved.
• Austenitizement (Hardening): The steel is heated to a temperature in the austenite forming zone, generally about 1875°F (1025°C). This step aims to change the structure of steel to that of austenite, where the carbon is dissolved. A rule of thumb for soak time at this temperature is 1 hour per inch (25 mm) thickness. This step requires keeping a protective environment in the furnace to avoid surface oxidation or decarburizing of the part. It is recommended for H13 steels to use an endothermic atmosphere with a dew point of 3 to 4 °C (38 to 40 °F) when austenitized at 1010 °C (1850 °F). Another common practice to protect a surface is to wrap the part in stainless steel foil.
• Quenching: H13, an air-hardening steel, is subjected to air quenching to achieve maximum hardness. Air quenching ensures that residual stresses are minimized post-hardening. But for larger sections, an air blast or even an oil quench may be needed to fully harden them. Water quenching is not ideal for H13 as the material is prone to cracking. Oil-quenched parts should be fully immersed until they reach bath temperature, then immediately placed in the tempering furnace.
• Tempering: H13 is a secondary hardening steel, with the need for tempering at a temperature greater than the secondary hardening peak (approx. 510°C – 950°F). Tempering is vital to relieve stresses and reach the desired compromise between hardness and toughness. Double tempering is a common practice. An example of an initial tempering step would be 400°F (205°C). The time for each tempering cycle is typically 2 hours per inch (25 mm) of thickness. The hardness level obtained will vary according to the tempering temperature applied. For instance, a heat treatment aiming for 45 HRC might involve tempering at 610 °C after hardening at 1020 °
• Stress Relieving: If dimensional accuracy is vitally important, rough-machined components can be treated with a stress-relieving treatment prior to the last hardening heat treatment. This means heating to 650 to 675 °C (1200 to 1250 °F), holding for 1 hour or more, and then slowly cooling to room temperature.
• Nitriding (Optional): If H13 parts have already received heat treatment, the finished parts can undergo nitriding, depending on the wear resistance required. This process is often carried out at temperatures similar to the tempering temperature, and thus, nitriding can sometimes serve as the second temper in a double-tempering treatment. For example, gas nitriding at 510 °C (950 °F) for 10 to 12 hours will produce a case depth of 0.10 to 0.13 mm (0.004 to 0.005 in.).

5. H13 equivalents

• Japanese Standard (JIS): SKD61 (sometimes listed as X40CrMoV5-1)
• German Standard (DIN): 1.2344, X40CrMoV5-1, GS344ESR
• European Standard (EN): X40CrMoV5-1 (1.2344)
• International Standard (ISO): X40CrMoV5-1
• Chinese Standard (GB/YB): 4Cr5MoSiV1
• Swedish Standard (ASSAB): 8407, 8402
• Austrian Standard (BOHLER): W302, W321
• American Standard (AISI/SAE/ASTM/UNS): H13, UNS T20813

6. Comparison of H11 and H13 steel

Key Differences between H11 and H13 Steel:

• Vanadium Content: H13 typically has a higher vanadium content (around 1%) than H11 (around 0.3-0.5%).
• Hot Hardness and Tempering Resistance: The higher vanadium content in H13 generally leads to better hot hardness and slightly improved tempering resistance.
• Toughness: H11 is often considered to have slightly higher toughness than H13. Some sources suggest that the increased vanadium in H13 might slightly decrease toughness, especially during quench embrittlement.
• Wear Resistance: Due to the greater dispersion of hard vanadium carbides, H13 generally offers higher wear resistance than H11.
• Applications (Nuances): While both are used for similar applications, H13 might be preferred for dies experiencing higher operating temperatures or requiring more wear resistance, whereas H11 might be selected when maximum toughness is critical. H13 is also very popular for plastic molds requiring high polish, especially ESR-refined grades.

In summary, choose H13 when better hot hardness, tempering resistance, and wear resistance are primary concerns. Choose H11 when slightly higher toughness is more critical for the application.