Coated cutting tool

A process for the production of a coated cutting tool consisting of a substrate body and a deposited coating, comprising the steps of:

• providing a substrate body, the substrate body being a WC—Co based cemented carbide body including from 5 to 15 wt % Co;
• subjecting a surface of the substrate body to a pre-treatment, the pre-treatment being an ion etching procedure, so that at least a 0.5 μm thickness of the substrate body is removed;
• depositing a 1 to 8 μm thick layer of a first TiAlN multilayer by a cathodic arc evaporation PVD process using at least two TiAl targets different in a Ti:Al atomic ratio in a chamber including nitrogen gas at a pressure of from 5 to 15 Pa, using a bias voltage of from −20 to −80 V, and at an applied arc current of from 50 to 200 A, the (Ti,Al)N multilayer consisting of a multilayer of alternating (Ti,Al)N sub-layers, wherein the atomic Ti:Al ratio of the at least two TiAl targets is chosen so that an overall atomic ratio of Ti:Al is from 33:67 to 67:33, wherein each of the individual (Ti,Al)N sub-layers has a thickness within the range from 1 to 25 nm, each of the individual (Ti,Al)N sub-layers being different in respect of the atomic ratio Ti:Al than an immediately adjacent (Ti,Al)N sub-layer, wherein the (Ti,Al)N multilayer is deposited in a manner so that it consists of two or more (Ti,Al)N sub-layer stacks arranged immediately on top of each other, wherein within the same (Ti,Al)N sub-layer stack there exists at least two types of individual (Ti,Al)N sub-layers, wherein the at least two types of individual (Ti,Al)N sub-layers have different Ti:Al atomic ratios, and wherein the overall Al content within each of the (Ti,Al)N sub-layer stacks increases from one (Ti,Al)N sub-layer stack to the next (Ti,Al)N sub-layer stack in the direction towards the outer surface of the first (Ti,Al)N multilayer;
• depositing a 0.3 to 1.5 μm thick layer of a first gamma-aluminium oxide layer by a reactive magnetron sputtering PVD process using at least one Al target in an oxygen containing gas volume at a total gas pressure of from 1 to 5 Pa, an oxygen partial pressure of from 0.001 to 0.1 Pa, at a temperature of from 400 to 600° C., using a power density at the magnetron of from 4 to 20 W/cm2, a bias voltage of from 80 to 200 V and a pulsed bias current of from 20 to 60 A;
• depositing a set of alternating layers of second (Ti,Al)N multilayers and second gamma-aluminium oxide layers, the second (Ti,Al)N multilayers and the second gamma-aluminium oxide layers are deposited using the same process conditions as when depositing the first (Ti,Al)N multilayer and the first gamma-aluminium oxide layer, respectively, wherein the number of each of second (Ti,Al)N multilayers and second gamma-aluminium oxide layers is ≥2, each of the second (Ti,Al)N multilayers being a multilayer of alternating (Ti,Al)N sub-layers, the overall atomic ratio of Ti:Al within the second (Ti,Al)N multilayers is from 33:67 to 67:33, the thickness of the second (Ti,Al)N multilayers is from 0.05 to 0.5 μm, each of the individual (Ti,Al)N sub-layers within the second (Ti,Al)N multilayers has a thickness of from 1 to 25 nm, each of the individual (Ti,Al)N sub-layers within the second (Ti,Al)N multilayers being different in respect of the atomic ratio Ti:Al than an immediately adjacent (Ti,Al)N sub-layer, the thickness of the second gamma-aluminium oxide layers is from 0.05 to 0.5 μm, wherein a total thickness of the deposited coating of the coated cutting tool is from 3 to 15 μm;
• subjecting the deposited coating to a first post-treatment procedure including shot peening using beads of a zirconium oxide based ceramic so that a compressive stress of at least 0.5 GPa is induced in the surface zone of the substrate body;
• and
• subjecting the deposited coating to a second post-treatment procedure by wet blasting with a slurry of aluminium oxide particles.