Features | Applications | Heat Treatment | Microstructure | Thermal Expansion Rate


High strength, tough and high heat check resistance hot work die steel.

DH31-EX is a hot working die steel with the best balance of strength and toughness showing the comparable softening resistance to SKD7 and twice hardenability as that of SKD61.


  • High hardenability: High toughness is obtained even in large size die.
  • High strength: High softening resistance at elevated temperature contributes to high wear
  • High toughness: DH31-EX has higher toughness than that of SKD61.
  • High heat check resistance: Excellent heat check resistance leads to longer life.

Take a look at DH31-EX NADCA Certification here.


  • Aluminum die cast dies especially for large size – long life use
  • Aluminum die cast parts such as pins and plunger sleeve
  • Hot forging dies
  • Hot pressing dies
  • Aluminum extrusion dies

Examples of Applications

Heat Treatment

Microstructure (Quenched and tempered)

Tempering Hardness

Softening Resistance


Fatigue Properties

CCT Curves

Quenching rate vs. Toughness

Heat Checking Resistance

Al Erosion Resistance

Hot Hardness

Nitriding Characteristics

Machinability Endmilling

Machinability Drilling

Thermal Expansion Rate

Thermal Conductivity

Specific Heat