The Difference Between Cold Work Die Steel and Hot Work Die Steel

Mold is an important technological foundation in the manufacturing industry, also known as the “mother of modern industry”. China is currently in a period of rapid development in mold manufacturing.

The existing types of mold steel are diverse, with different uses for various molds, differing in hardness, strength, wear resistance, toughness, as well as quenching penetration, hardenability, and other process performance.

According to their use characteristics, mold steel can be roughly divided into three categories: cold work die steel, hot work die steel, and plastic mold steel, which are used for forging, stamping, cutting, die casting, etc.

Now let’s briefly introduce the differences between cold work die steel and hot work die steel.

Cold work die steel


Cold work die steel includes molds for punching and trimming (blanking and punching dies, trimming dies, punching heads, and scissors), cold heading dies, cold extrusion dies, bending dies, and drawing dies, etc.

Working conditions

During the working process of cold work die steel, the working part of the mold endures significant pressure, bending force, impact force, and frictional force, due to the large deformation resistance of the processed material. Thus, the mold requires high hardness and wear resistance, high bending strength and sufficient toughness to ensure the smooth progress of the stamping process.


  • Small-sized, simple-shaped, and light-loaded cold work molds;

  • Large-sized, complicated-shaped, and light-loaded cold work molds;

  • Large-sized, complicated-shaped, and heavy-loaded cold work molds;

  • Cold work molds that are subjectedto impact loads and have thin knife intervals.

Hot work die steel


Hot work die steel includes hammer forging molds, hot extrusion molds, and die-casting molds.

Working conditions

Hot work die steel works under the condition of being in contact with hot metal, therefore it requires high heat resistance, including high-temperature hardness and strength, high plastic deformation resistance, and excellent heat fatigue resistance, which ensure the smooth running of the stamping process.


  • Steels for hammer forging dies, with high mechanical properties, especially high plastic change resistance and toughness;

  • Steels for hot extrusion dies, with high tempering stability and high heat-resistant fatigue properties;

  • Die casting die steel, from a general point of view, die casting die steel performance requirements and hot extrusion die steel similar, that is, to require high tempering stability and high thermal fatigue resistance.

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