Cutting performance and wear mechanism of cutting tool in milling of high strength steel 34CrNiMo6

34CrNiMo6 is a newly developed engineering material for high load carrying component with its high strength, hardness and toughness. Face milling experiments were carried out with cemented carbide and coating inserts respectively for this difficult-to-cut material, the relationship between cutting tool life and cutting speed was established, and the suitable cutting tool material and corner radius were determined. Furthermore, the wear characteristic and mechanism of experimental inserts were investigated with the application of scanning electronic microscope(SEM) and energy spectrum analysis. The analysis results show that severe thermal wear such as oxygenation and diffusion wear are the main reason for the premature breakage for cemented carbides cutting tools, while the thermal wear is caused by the high cutting force and temperature in the high efficiency milling process of the high toughness material. Tool life of coating tool is significantly prolonged by the abrasion resistance improvement and heat transfer shield effect of coating. For the worn insert, the depth of crater in coating tool is much more than that of un-coating tool, and the wear form in rake face is characterized by rectangular crater for the coating reduce the expansion of crater along rake face effectively.