Cold working die steel refers to the die steel used to deform or form metal in cold state. When the cold working die steel is working, the working part of the die bears great pressure, bending force, impact force and friction force due to the large deformation resistance of the processed material. Therefore, the normal scrapping reason of cold working die is generally wear and tear, and also premature failure due to fracture, collapse force and out of tolerance deformation.

冷作模具钢与刃具钢相比．有许多共同点。要求模具有高的硬度和耐磨性、高的抗弯强度和足够的韧性，以保证冲压过程的顺利进行、其不同之处在于模具形状及加工艺复杂．而且摩擦面积大．磨损可能性大．所以修磨起来困难。因此要求具有更高的耐磨化模具工作时承受冲压力大．又由于形状复杂易于产生应力集中，所以要求具有较高的韧性；模具尺寸大、形状复杂．所以要求较高的淬透性、较小的变形及开裂倾向性。

Compared with cutting tool steel, cold working die steel has a lot in common. High hardness and wear resistance, high bending strength and enough toughness are required to ensure the smooth stamping process. The difference lies in the complex die shape and processing, large friction area and high wear possibility, so it is difficult to repair. Because of the complex shape, it is easy to produce stress concentration, so it requires higher toughness; The mould is large in size and complex in shape, so it requires higher hardenability, smaller deformation and cracking tendency.

总之，冷作模具钢在淬透性、耐磨性与韧性等方面的要求要较刃具钢高一些．而在红硬性方面却要求较低或基本上没要求（因为是冷态成形），所以也相应形成了一些适于做冷作模具用的钢种，例如，发展了高耐磨、微变形冷作模具用钢及高韧性冷作模具用钢等。下面结合有关钢种选用进一步说明。

In a word, the requirements of hardenability, wear resistance and toughness of cold working die steel are higher than those of cutting tool steel, but the requirements of red hardness are lower or basically not required (because it is cold forming), so some suitable steel grades for cold working die have been formed correspondingly, for example, high wear resistance, micro deformation cold working die steel and high toughness cold working die steel have been developed. The following is further explained in combination with the selection of relevant steel grades.

性能：高碳、高铬类型莱氏体钢，具有较好的淬透性和良好的耐磨性。由于钢中碳质量分数高可达2.30%，从而钢变得硬而脆，所以冲击韧性较差，几乎不能承受较大的冲击荷载，易脆裂，而且易形成不均匀的共晶碳化物。

Properties: high carbon and high chromium ledeburite steel with good hardenability and wear resistance. Because the carbon content in steel is up to 2.30%, the steel becomes hard and brittle, so the impact toughness is poor, it can hardly bear large impact load, it is easy to crack, and it is easy to form non-uniform eutectic carbide.