A coated cutting tool comprising a substrate containing a cubic boron nitride-containing sintered body, and a coating layer formed on the substrate, wherein the coating layer comprises a lowermost layer and an alternating laminate structure in this order, the lowermost layer comprises (Al.sub.1-xCr.sub.x)N, an average thickness of the lowermost layer is 0.01 μm or more and 0.2 μm or less, the alternating laminate structure includes mutually different two kinds of compound layers of a first compound layer containing (Al.sub.1-y1Cr.sub.y1)N and a second compound layer containing (Al.sub.1-y2Cr.sub.y2)N alternately laminated repeatedly twice or more, an average thickness of the entire alternating laminate structure is 0.1 μm or more and 1.2 μm or less, an average thickness of the entire coating layer is 0.2 μm or more and 1.3 μm or less, and a compressive residual stress at the cubic crystal (111) plane is 3.0 GPa or less.

A covered cutting tool having a cemented carbide and a covering layer formed on the cemented carbide. The covered cutting tool includes a rake face, a flank face, and a cutting edge line part located between the rake face and the flank face. The coating layer includes a compound layer containing a compound having a composition represented by (Al.sub.xTi.sub.1-x)N. The average thickness T.sub.1 of the covering layer in the cutting edge line part and the average thickness T.sub.2 of the coating layer in the rake face at a position 2 mm or more away from the cutting edge line part toward the rake face are within specific ranges and satisfy T.sub.2<T.sub.1. The residual stress S.sub.1 of the cemented carbide in the cutting edge line part and the residual stress S.sub.2 of the cemented carbide in the rake face at a position 2 mm or more away from the cutting edge line part toward the rake face satisfy S.sub.2<S.sub.1.

A cutting blade having a plurality of different coatings on surfaces thereof, including an upper surface, a lower surface, and a side surface connecting the upper surface and the lower surface, wherein the upper surface intersects the side surface to form at least one cutting edge unit, the cutting edge unit includes a main cutting edge and a secondary cutting edge, the upper surface includes at least one set of cutting planes, the cutting planes include a main cutting surface and a secondary cutting surface, the main cutting surface intersects the side surface to form the main cutting edge, the secondary cutting surface intersects the side surface to form the secondary cutting edge, a main coating is provided on the main cutting surface, a secondary coating is provided on the secondary cutting surface, and the main coating and the secondary coating are independent from each other.

A surface-coated cutting tool has a hard coating layer including an upper layer α, an adhesion layer β, and a lower layer γ. The upper layer α is formed of an α-Al.sub.2O.sub.3 layer formed under low temperature conditions. The adhesion layer β includes a TiCN layer having a thickness of 0.5 μm or more in an outermost layer and contains 0.5 to 3 μm to a maximum depth of 0.5 μm toward the inside in a layer thickness direction of the TiCN layer from the interface between the TiCN layer and the upper layer α. The lower layer γ is formed of (Ti.sub.1-XAl.sub.X)(C.sub.YN.sub.1-Y) of a single phase of a NaCl type face-centered cubic structure, in which an average content ratio X.sub.avg of Al and an average content ratio Y.sub.avg of C in this composition formula satisfy 0.60≤X.sub.avg≤0.95 and 0≤Y.sub.avg≤0.005.

A surface coated cutting tool comprises a base material and a coating layer that coats the base material, the coating layer including an alternate layer composed of a first unit layer and a second unit layer alternately stacked, the first unit layer being composed of a nitride containing aluminum and zirconium, in the first unit layer, when the total number of metal atoms constituting the first unit layer is represented as 1, a ratio thereto of the number of atoms of the zirconium being not less than 0.65 and not more than 0.95, the second unit layer being composed of a nitride containing titanium and aluminum, in the second unit layer, when the total number of metal atoms constituting the second unit layer is represented as 1, a ratio thereto of the number of atoms of the aluminum being larger than 0.40 and not more than 0.70.

A cutting tool includes: a substrate; a hard layer provided on the substrate; and a titanium carbonitride layer provided on the hard layer, wherein a thickness of the titanium carbonitride layer is more than or equal to 2 μm, a hardness of the titanium carbonitride layer at a room temperature is more than or equal to 35 GPa, and a Young's modulus of the titanium carbonitride layer at the room temperature is more than or equal to 800 GPa.

A cutting tool comprises a substrate and an AlTiN layer, the AlTiN layer including a first major surface and a second major surface, the AlTiN layer including a first region having a distance of 0 nm or more and 30 nm or less from the first major surface and having a maximum oxygen content ratio of more than 0 atomic % and less than 5 atomic %, a second region having a distance of more than 30 nm and 100 nm or less from the first major surface and having a maximum oxygen content ratio of 5 atomic % or more and 30 atomic % or less, and a third region having a distance of more than 100 nm and 150 nm or less from the first major surface and having a maximum oxygen content ratio of more than 0 atomic % and less than 5 atomic %.

A cutting tool comprises a substrate and an AlTiN layer, the AlTiN layer including a first major surface and a second major surface, the AlTiN layer including a first region having a distance of 0 nm or more and 30 nm or less from the first major surface and having a maximum oxygen content ratio of 30 atomic % or more, a second region having a distance of more than 30 nm and 100 nm or less from the first major surface and having a maximum oxygen content ratio of 5 atomic % or more and less than 30 atomic %, and a third region having a distance exceeding 100 nm from the first major surface and having a maximum oxygen content ratio of less than 5 atomic %.

Provided is a coated cutting tool having improved wear resistance and fracture resistance and a long tool life. The coated cutting tool includes a substrate, and a coating layer formed on a surface of the substrate. The coating layer has a laminated structure in which a first layer and a second layer are alternately laminated for one or more layers. The first layer is a compound layer having a composition represented by Ti(C.sub.xN.sub.1-x). The second layer is a compound layer having a composition represented by (Ti.sub.yAl.sub.1-y)N. The laminated structure includes first to third laminated structures in this order from a substrate side to a surface side of the coating layer. An average thickness per layer of each of the first layer and the second layer in the first to third laminated structures is in a specific range. An average thickness of the first to third laminated structures is in a specific range.

A surface-coated cutting tool has a hard coating layer including an upper layer α, an adhesion layer β, and a lower layer γ. The upper layer α is formed of an α-Al.sub.2O.sub.3 layer formed under low temperature conditions. The adhesion layer β includes a TiCN layer having a thickness of 0.5 μm or more in an outermost layer and contains 0.5 to 3 μm to a maximum depth of 0.5 μm toward the inside in a layer thickness direction of the TiCN layer from the interface between the TiCN layer and the upper layer α. The lower layer γ is formed of (Ti.sub.1-XAl.sub.X)(C.sub.YN.sub.1-Y) of a single phase of a NaCl type face-centered cubic structure, in which an average content ratio X.sub.avg of Al and an average content ratio Y.sub.avg of C in this composition formula satisfy 0.60≤X.sub.avg≤0.95 and 0≤Y.sub.avg≤0.005.