Fine grained cemented carbide cutting tool insert

Method of turning heat resistant superalloys and stainless steels at a cutting speed of from about 30 to about 250 m/min and a feed of from about 0.1 to about 0.4 mm/rev, using a cutting tool insert comprising a substrate and a coating, wherein the substrate comprises WC with a grain size of from about 0.4 to about 1.0 μm, from about 5 to about 8 wt % Co, Cr such that the Cr/Co-ratio by weight is from about 0.05 to about 0.15, and ppm levels of Ta, Ti or mixtures thereof, present in such amounts that a ratio Me/Co=(at-% Ti+at-% Ta)/at-% Co is lower than or equal to about 0.014−(CW_Cr)*0.008 and higher than about 0.0005, and CW_Cr is from about 0.75 to about 0.95, wherein

• CW_Cr=(magnetic-% Co+1.13*wt-% Cr)/wt-% Co,
• wherein magnetic-% Co is the weight percentage of magnetic Co, wt-% Cr is the weight percentage of Cr and wt-% Co is the weight percentage of Co in the cemented carbide, and
• the coating is a PVD TixAl1-xN-coating with an average composition of x being greater than about 0.4 but less than about 0.9, present as a single or multilayer coating with a total thickness of more than about 1 μm but less than about 6.0 μm.