US Patent 7901796 Coated cutting tool and manufacturing method thereof

A coated cutting tool and its manufacturing method are provided. The coated cutting tool includes a base material and a coating layer formed on a surface of the base material. The coating layer includes an alternate layer having at least one layer of each of an A layer and a B layer stacked one on another alternately. The A layer is made of a nitride containing Al and Cr, and when the total number of metal atoms constituting the A layer is represented as 1, a ratio of the number of Cr atoms is more than 0 and not more than 0.4. The B layer is made of a nitride containing Ti and Al, and when the total number of metal atoms constituting the B layer is represented as 1, a ratio of the number of Al atoms is more than 0 and not more than 0.7.