US Patent 8012611 Surface-coated cutting tool

The present invention relates to a surface-coated cutting tool comprising a substrate and a coating formed on the substrate, the coating includes a first coating of TiCN and a second coating of α-type Al2O3, the first coating is located between the substrate and the aforementioned second coating, and the second coating has compressive stress S1 in an area A1 spreading from an insert ridge portion in the direction of a rake face and the direction of a flank face with distances of at least 0.5 mm respectively and has tensile stress S2 in an area A2 other than this area A1, while compressive stress S1 and tensile stress S2 are defined by the following expression (I):400 MPa≦|S1−S2|≦3500 Mpa   (I).