A method of producing a coated tool part of a cutting tool. The tool part is coated with a coating containing at least one aluminum oxide (Al.sub.2O.sub.3) containing Al.sub.2O.sub.3-layer having an alpha-Al.sub.2O.sub.3 phase fraction and a gamma-Al.sub.2O.sub.3 phase fraction. The at least one Al.sub.2O.sub.3-layer is produced using a reactive magnetron sputtering process.

The present disclosure relates to a method of treating a cutting tool of a cemented carbide or cermet substrate, wherein the cutting tool is subjected to shot peening at a temperature of or above 100 C. The cutting tool typically has a rake face, a flank face and a cutting edge extending therebetween. The shot peening is performed at least on the rake face of the cutting tool. The present disclosure also relates to a cutting tool treated with the method.

A coated cutting tool includes a substrate and a hard film that is formed thereon. The hard film is a nitride in which with respect to a total amount of metal elements (including metalloid), Al is 60 at % or more and 70 at % or less, Ti is 20 at % or more and 40 at % or less, and one or more selected from W, Cr, Ta, Nb, Zr, Mo, and V are 1 at % or more and 10 at % or less, and with respect to a total amount of metal elements (including metalloid), a nitrogen element, and an Ar element, Ar is contained in an amount of 0.01 at % or more and 0.15 at % or less. A crystal structure of the hard film is a face-centered cubic lattice structure, and a half-value width of an X-ray diffraction peak of a (111) plane is 0.75 or more and 0.95 or less.

A coated tool includes a base body and a coating layer located on the base body. The coating layer includes plurality of Ta-containing multilayer structures and a plurality of Mo-containing multilayer structures. Each of the plurality of Ta-containing multilayer structures includes a first compound layer containing Ta at a first composition ratio and a second compound layer containing Ta at a second composition ratio different from the first composition ratio. Each of the plurality of Mo-containing multilayer structures includes a third compound layer containing Mo at a third composition ratio and a fourth compound layer containing Mo at a fourth composition ratio different from the third composition ratio.