The hot working die is subjected to great impact force during operation. The die cavity contacts with high temperature metal and is heated and cooled repeatedly, so its operation condition is extremely bad. In order to meet the application requirements of hot working die, hot working die steel should have the following basic characteristics:

1、较高的高温强度和出色的耐性。热作模具，尤其是热锻模，作业时接受很大的冲击力，并且冲击频率很高，假设模具没有高的强度和出色的耐性，就简单开裂。

1. High temperature strength and excellent resistance. Hot working dies, especially hot forging dies, are subject to great impact force and high impact frequency during operation. Assuming that the dies do not have high strength and excellent resistance, they will simply crack.

2、出色的耐磨功用，由于热作模具丁作时除遭到毛坯变形时发生冲突磨损之外，还遭到高温氧化腐蚀和氧化铁屑的研磨，所以需求热作模具钢有较高的硬度和抗黏附性。

2. Due to the excellent wear-resistant function, the hot working die steel is required to have high hardness and anti adhesion because it is not only subject to conflict wear when the blank is deformed, but also subject to high-temperature oxidation corrosion and grinding of iron oxide chips.

3、高的热稳定性。热稳定性是指钢材在高温下可长时刻坚持其常温力学功用的才能。热作模具作业时，接触的是炽热的金属，甚是液态金属，所以模具表面温度很高，一般为400～700℃。这就要求热作模具钢在高温下不发生热化，具有高的热稳定性，不然模具就会发生塑性变形，造成堆塌而失效。

3. High thermal stability. Thermal stability refers to the ability of steel to adhere to its mechanical function at room temperature for a long time at high temperature. When the hot working die works, the contact is hot metal, even liquid metal, so the surface temperature of the die is very high, generally 400 ~ 700 ℃. This requires that the hot work die steel does not heat at high temperature and has high thermal stability, otherwise the die will have plastic deformation, resulting in collapse and failure.

4、优异的耐热疲乏性，热作模具的作业特点是反复受热受冷，模具一时受热胀大，一时又冷却缩短，构成很大的热应力，并且这种热应力是方向相反，替换发生的。在反复热应力作用下，模具表面会构成网状裂纹(龟裂)，这种现象称为热疲乏，模具因热疲乏而过早地开裂，是热作模具失效的主要原因之一。所以热作模具钢有必要要有出色的热疲乏性。

4. Excellent heat resistance and fatigue. The operation characteristics of hot working die are repeated heating and cooling. The die is subject to large thermal expansion at one time and short cooling at one time, which forms a large thermal stress. Moreover, the direction of this thermal stress is opposite and the replacement occurs. Under the action of repeated thermal stress, the surface of the die will form a network crack (cracking), which is called thermal fatigue. The premature cracking of the die due to thermal fatigue is one of the main reasons for the failure of the hot working die. Therefore, it is necessary for hot work die steel to have excellent thermal fatigue.

5、高淬透性。热作模具一般尺度比较大，热锻模尤其是这样，为了使整个模具截面的力学功用均匀，这就要求热作模具钢有高的淬透功用。

5. High hardenability. Hot working die generally has a large scale, especially for hot forging die. In order to make the mechanical function of the whole die section uniform, it requires high hardenability of hot working die steel.

6、出色的导热性。为了使模具不致积热过多，导致力学功用下降，要尽或许降低模面温度，减小模具内部的温差，这就要求热作模具钢要有出色的导热件能。

6. Excellent thermal conductivity. In order to avoid excessive heat accumulation in the die and decrease the mechanical function, it is necessary to reduce the temperature of the die surface and the temperature difference inside the die as much as possible, which requires that the hot work die steel should have excellent thermal conductivity.

7、出色的成形加工工艺功用，以满足加工成形的需求。

7. Excellent forming process function to meet the needs of forming.