AISI H12 Hot Work Tool Steel – High Toughness Solution for Forging and Die Casting Applications

Property	Typical Value
Density	7.8 g/cm³
Hardness (Annealed)	≤ 229 HB
Hardness (Hardened & Tempered)	44–52 HRC
Tensile Strength	1500–1900 MPa
Yield Strength	Approx. 1200 MPa
Elongation	10–15%
Impact Toughness	Excellent at high temperatures

These properties allow AISI H12 tools to operate in aggressive environments such as hot forging dies and die-casting molds without premature wear or cracking.

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4. Heat Treatment Process

To achieve optimal properties, AISI H12 must undergo a proper heat treatment sequence. This process enhances hardness, strength, and dimensional stability.

Annealing

• Heat to 850–900°C

• Hold for 2–4 hours

• Furnace cool to 600°C, then air cool
  Result: Soft structure (≤229 HB) for easy machining.

Preheating

• Gradual preheating in two stages:

  1. 450–500°C

  2. 850–900°C

Hardening

• Austenitize at 1000–1050°C

• Hold for 20–30 minutes

• Air or oil quench
  Result: Hardness up to 52 HRC.

Tempering

• Temper immediately after quenching.

• Double tempering recommended at 500–650°C.

• Final hardness adjusted to 44–52 HRC based on tool requirements.

Proper heat treatment ensures a fine microstructure, high strength, and resistance to thermal shock.

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5. Key Benefits of AISI H12

AISI H12 Hot Work Tool Steel offers several unique advantages that make it the preferred choice for tooling and die applications:

1. High Hot Strength
   Retains mechanical integrity even above 600°C.

2. Excellent Thermal Fatigue Resistance
   Resists heat checking and cracking during repeated heating cycles.

3. Superior Toughness
   Outstanding shock and impact resistance under forging pressures.

4. Good Dimensional Stability
   Minimal distortion after heat treatment.

5. Resistance to Softening
   Maintains hardness at elevated temperatures.

6. Wear and Abrasion Resistance
   Excellent performance in high-friction environments such as extrusion dies.

7. Extended Tool Life
   Reduced downtime and cost per cycle for industrial users.

These advantages make AISI H12 an all-around solution for both precision and heavy-duty hot work tools.

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6. Applications of AISI H12 Hot Work Tool Steel

AISI H12’s versatility extends across several critical industrial sectors, including forging, die casting, and extrusion.

1. Forging Applications

• Drop forging dies

• Press forging dies

• Hot trimming dies

• Hammer dies
  AISI H12 is particularly useful in heavy-duty forging operations, where die life and impact resistance are crucial.

2. Die Casting Applications

• Pressure die-casting molds

• Core pins, inserts, and sleeves

• Hot chamber and cold chamber dies
  Its ability to resist thermal cracking makes it ideal for zinc, aluminum, and magnesium die casting molds.

3. Extrusion Tools

• Aluminum and copper extrusion dies

• Container liners

• Mandrels and stems
  AISI H12 provides excellent wear resistance during the extrusion of non-ferrous metals.

4. Aerospace and Automotive Tools

• Hot forming dies for exhaust manifolds

• Turbine blade molds

• Valve and injector components

5. Hot Shear Blades and Cutters

• Hot trimming knives

• Shear blades for red-hot steel bars and billets

These applications demonstrate AISI H12’s performance versatility and long service life under demanding operating conditions.

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7. Comparison: AISI H12 vs AISI H13

Although H13 is often seen as the industry benchmark, H12 provides distinct advantages in specific use cases.