Hardness is one of the most important representative properties of die steel. In the actual mold design and production, the material performance is often the key factor to determine the mold quality. Therefore, it is of great significance to use portable instruments to quickly and accurately detect the hardness of the mold before processing. It can improve the quality and manufacturing level of die steel and prolong the service life of die.

模具钢材是模具工业的主要材料。模具钢材应根据模具的使用条件、环境和状态具有不同的特性。模具钢材的硬度测试主要针对三种情况，即模具钢材的硬度测试、热处理后半成品模具的硬度测试和要求高耐磨性的热处理后模具的表面硬度测试。

Die steel is the main material of die industry. Die steel should have different characteristics according to the use conditions, environment and state of the die. The hardness test of die steel mainly aims at three situations, namely, the hardness test of die steel, the hardness test of semi-finished die after heat treatment and the surface hardness test of die after heat treatment which requires high wear resistance.

硬度是模具材料和成品模具的重要性能指标。工字加工过程中模具的应力状态是复杂的。例如，热作模具在交变温度场下通常承受交变应力，因此它应具有良好的防止模具变成软或塑性状态的能力，并在长期工作环境下保持模具的形状和尺寸精度不变。

Hardness is an important performance index of die material and finished die. The stress state of the die in the process of I-shaped machining is complex. For example, the hot working die usually bears alternating stress under alternating temperature field, so it should have good ability to prevent the die from becoming soft or plastic, and keep the shape and dimensional accuracy of the die unchanged under long-term working environment.

耐磨性也是成品模具的重要性能指标。当零件成形时，金属和模具的型腔表面相对于彼此移动并磨损型腔表面，导致模具的尺寸、形状、精度和表面粗糙度改变并变得无效。模具的耐磨性取决于模具的热处理，尤其是表面热处理。评估模具耐磨性的主要依据是硬度。

Wear resistance is also an important performance index of the finished mold. When a part is formed, the cavity surfaces of the metal and the die move relative to each other and wear the cavity surface, resulting in the change of the size, shape, accuracy and surface roughness of the die and becoming invalid. The wear resistance of the die depends on the heat treatment of the die, especially the surface heat treatment. The main basis for evaluating the wear resistance of die is hardness.

根据标准要求，工厂状态的模具钢材应使用布氏硬度计进行硬度测试。然而，模具钢材通常尺寸较大，不能在布氏硬度试验机上直接测试。通常的方法是从钢中取样，经过适当的处理后，在布氏硬度计上进行测试。

According to the standard requirements, the hardness of die steel in factory condition shall be tested by Brinell hardness tester. However, die steel is usually too large to be tested directly on Brinell hardness tester. The usual method is to take samples from the steel and test them on Brinell hardness tester after proper treatment.