Die steel is a kind of steel used to manufacture cold stamping die, hot forging die, die casting die and so on. So what are the requirements and characteristics of die steel in terms of working performance? The details are as follows.

模具钢性能的要求和特点

Requirements and characteristics of die steel properties

硬度

hardness

模具在工作时受力状态是复杂的，如热作模具通常在交换的温度场下承受交变应力作用，因此它应具有良好的抗软化或塑性变形状态的能力，在长期工作环境下仍能保持模具的形状和尺寸精度。硬度是模具钢的生要性能之一。对冷作模具的硬度一般选择在58HRC以上，而热作模具尤其是要求高的抗热疲劳性能的模具，通常硬度在45HRC左右。对普通使用的塑料模具，一般硬度要求在35HRC左右。

The stress state of the die during operation is complex. For example, the hot working die usually bears the action of alternating stress under the exchange temperature field. Therefore, it should have good ability to resist softening or plastic deformation, and can still maintain the shape and dimensional accuracy of the die in the long-term working environment. Hardness is one of the important properties of die steel. The hardness of cold working dies is generally above 58hrc, while the hardness of hot working dies, especially those requiring high thermal fatigue resistance, is usually about 45hrc. For ordinary plastic molds, the general hardness is required to be about 35hrc.

强度与韧性

Strength and toughness

零件在成形使模具承受着巨大的的冲击、扭曲等负荷，尤其是现代高速冲压、高速精密锻造和液态成形等技术以及一次成形技术的发展，模具承受着更大的负荷，往往由于钢材的强度和韧度不够，造成型腔边缘或局部塌陷、崩刃或断裂而早期失效，因此模具热处理后应具有较高的硬度和韧度。

The forming of parts makes the die bear huge loads such as impact and distortion. Especially with the development of modern high-speed stamping, high-speed precision forging, liquid forming and one-time forming technology, the die bears greater loads. Often, due to the insufficient strength and toughness of steel, the edge or local collapse, edge collapse or fracture of the cavity are caused and the die fails early, Therefore, the die should have high hardness and toughness after heat treatment.

耐磨性

Wear resistance

零件成形时材料与模具型腔表面发生相对运动，使型腔表面产生了磨损，从而使得模具的尺寸精度、形状和表面的粗糙度发生变化而失效。磨损是一种复杂的过程，影响因素很多，除取决于作用于模具的外界条件外，还在很大程度上取决于采用钢材的化学成分不均匀性、组织状态、力学性能等。

During part forming, the relative movement between the material and the die cavity surface causes the wear of the cavity surface, resulting in the change of the dimensional accuracy, shape and surface roughness of the die. Wear is a complex process with many influencing factors. In addition to the external conditions acting on the die, it also depends to a great extent on the non-uniformity of chemical composition, microstructure and mechanical properties of steel.

疲劳性能

Fatigue performance

模具工作时承受着机械冲击和热冲击的交变应力，热作模具在工作的过程中，热交变应力更明显地导致模具热裂。受应力和温度梯度的影响而引起裂纹，往往是在型腔表面形成浅而细的裂纹，它的迅速传播和扩展导致模具失效。另外，钢的化学成分及组织的不均匀，钢中存在的冶金缺陷如非金属夹杂物，气孔、显微裂纹等均可导致钢的疲劳强度降低，因为在交变应力的作用下，在这些薄弱地区产生疲劳裂纹并发展为疲劳破坏

When the die works, it bears the alternating stress of mechanical impact and thermal impact. During the working process of hot working die, the thermal alternating stress more obviously leads to the hot crack of the die. Cracks caused by stress and temperature gradient often form shallow and fine cracks on the surface of the cavity. Its rapid propagation and propagation lead to die failure. In addition, the uneven chemical composition and structure of the steel, and the metallurgical defects in the steel, such as non-metallic inclusions, pores and microcracks, can reduce the fatigue strength of the steel, because under the action of alternating stress, fatigue cracks first occur in these weak areas and develop into fatigue failure

粘着性

Adhesion

工模具零件的表面由于两金属原子相互摭用或单相扩散的作用，往往会有一些被加工金属粘附着，尤其是一些切削、剪切工具和冲压工具的表面会产生粘附或结疤现象，这会影响刃口的锋利程度和局部组织、化学成分的改变，使刃口部分崩裂或粘附金属的脱落划伤模具，使工件表面粗糙。因此良好的抗粘着性也是很重要的。

Due to the interaction of two metal atoms or single-phase diffusion on the surface of tool and die parts, some processed metals tend to adhere, especially the surface of some cutting, shear tools and stamping tools will produce adhesion or scarring, which will affect the sharpness of the edge and the change of local structure and chemical composition, Make the edge part crack or the falling off of adhered metal scratch the die, making the workpiece surface rough. Therefore, good adhesion resistance is also very important.