Plastic products have been widely used in industry and daily life, depending on the type of plastic, product use, molding method and production batch size. It is generally required that the heat treatment process is simple, the heat treatment deformation is small or no deformation, the cutting performance in the pre hard state is good, the mirror polishing performance and pattern etching performance are excellent, the surface roughness is low, and the service life is long.

① 切削加工性能 对于大型、复杂的挤压和注射模具，通常预硬化到28-35HRC之间，再进行切削和磨削加工所要求的尺寸和精度后，直接投入使用，从而避免了热处理变形、氧化和脱碳的缺陷。加入易切削元素S、Co和稀土，用以改善硬钢的切削加工性能。

① Cutting performance for large and complex extrusion and injection mold, usually pre hardening to 28-35hrc, then cutting and grinding to the required size and precision, directly put into use, thus avoiding the defects of heat treatment deformation, oxidation and decarburization. Free cutting elements s, CO and rare earth are added to improve the machinability of hard steel.

② 镜面加工性能 激光盘和塑料透镜等塑料制品的表面粗糙度要求很高，主要由模具型腔的粗糙度来保证，一般模具型腔的粗糙度要比塑料制品的高一级。模具钢的镜面加工性能与钢的纯洁度、组织、硬度和镜面加工技术有关。硬度高、显微组织细小而均匀、非金属夹杂少，均有利于提高镜面抛光性。镜面抛光性要求高的塑料模具钢常采用真空熔炼或真空除气。

② The surface roughness of plastic products such as laser disc and plastic lens is required to be very high, which is mainly guaranteed by the roughness of mold cavity. Generally, the roughness of mold cavity is one level higher than that of plastic products. The mirror finishing performance of die steel is related to the purity, structure, hardness and mirror processing technology of the steel. High hardness, fine and uniform microstructure and less nonmetallic inclusions are beneficial to improve the mirror polishing performance. Vacuum melting or vacuum degassing are often used for plastic mold steel with high mirror polishing performance.

③ 图案蚀刻性能 某些塑料制品表面要求呈现清晰而丰满的图案花纹，还有皮革工业中的大型皮纹压花版，都要求模具钢有良好的图案光刻性能，图案光刻性能对材质的要求与镜面抛光性能相似，钢的纯洁订要高，组织要致密，硬度要高。

③ Pattern etching performance the surface of some plastic products requires clear and full pattern patterns, as well as the large leather embossed plate in the leather industry, all require the mold steel to have good pattern lithography performance. The requirements of pattern lithography performance on material are similar to mirror polishing performance. The purity of steel should be high, the structure should be dense and the hardness should be high.

④ 耐蚀性能 含氯和氟的树脂以及在ABS树脂中添加抗燃剂时，在成型过程中将释放出有腐蚀性的气体。对于这类塑料模具要选用耐蚀塑料模具钢或表面镀铬或采用镍磷非晶态表面涂层。

④ Corrosion resistance of resin containing chlorine and fluorine and adding flame retardant to ABS resin will release corrosive gas during molding process. For this kind of plastic mould, corrosion-resistant plastic mould steel or chromium plating or nickel phosphorus amorphous surface coating should be used.