The addition of copper and sulfur can improve the cutting performance of the pre-hardened plastic mold steel, and the effect of improving the cutting performance is similar, and both have the effect of wrapping lubrication and reducing friction. The four types of P20 plastic mold steels were adjusted to the same hardness level through the heat treatment process, and the microstructure and mechanical properties were compared with the optical microscope, scanning electron microscope, transmission electron microscope, and universal tensile testing machine. At the same time, the high-speed turning experiment and optical profile were used. Instrument to compare and study their cutting and polishing performance. The research results showed that under the same cutting conditions, the addition of copper were reduced the cutting force about 13%, the cutting life of the tool was significantly improved, and the surface finish of the steel after cutting was improved about 15%, compared to 718 steel. The comparison of mechanical properties, polishing properties and machining properties showed that SDP1Cu steel has the best comprehensive properties. The addition of Cu element is helpful to improve the machining properties of steel.
Keywords: free cutting, plastic mold steel, mechanical properties, processing properties