Abstract: Experiments conducted to determine the effect of copper addition on the machinability of plastic mould steel 4Cr16Mo were presented. The machinability of mould steel 4Cr16Mo was improved obviously by adding Cu. The top wear of 4Cr16Mo with copper was less than that without copper. Cu-rich phase had the effect of lubricant and heat conductivity as solid lubricant, which reduced cutting-tool wear, improved machinability and increased service life of cutting-tool. With the increase of copper addition, the hot-working character of 4Cr16Mo decreased. The optimal hot-working parameters 4Cr16Mo with copper were determined by tensile test and compression test. The rate of deformation should be adopt as 0.6 s-1. The heating-up temperature, initial forging temperature and terminal forging temperature were 1200℃, 1150℃ and 950℃, respectively.

Key words: machinability, cutting-tool, hot-shortness, Cu-rich phase