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 less than or equal to 650 GPa.

Provided is a coated cutting tool having a base material side single layer portion and a laminated portion provided as a hard coating in order from a base material side. The base material side single layer portion is formed of a nitride-based hard coating in which a proportion of Al is highest among metal (including metalloid) elements, a sum of Al and Cr in a content ratio (atomic ratio) is 0.9 or more, and at least B is contained. In the laminated portion, a nitride-based a layer in which a proportion of Ti is highest among metal (including metalloid) elements and at least B is contained, and a nitride-based b layer in which a proportion of Al is highest among metal (including metalloid) elements and at least Cr and B are contained are alternately laminated.

A polycrystalline cubic boron nitride includes a cubic boron nitride particle group. The ratio of a second length to a first length is 0.99 or less. Here, each of the first length and the second length is a value measured on a surface of the polycrystalline cubic boron nitride with an indentation formed by a Knoop hardness test under conditions specified in ISO4545-1 and ISO4545-4. The second length represents the length of the longer diagonal of the indentation. The first length represents the sum of the second length and the length of the streaky indentation.

A surface-coated cutting tool comprises a tool substrate comprising a cBN sinter and a hard coating layer including a lower sublayer α and an upper sublayer β on the surface of the cutting edge; wherein α satisfies (Al.sub.1-xTi.sub.x)N (0.40≤x≤0.60); β satisfies (Al.sub.1-y-zTi.sub.yB.sub.z)N (0.40≤y≤0.60 and 0.01≤z≤0.10); in the sublayer β, the variation in the concentration of the B component is repeated; the average Bmaxav of the maxima in the concentration of the B component satisfies z<Bmaxav≤2.0×z, and the average Bminav of the minima in the concentration of the B component satisfies 0≤Bminav<z; and the average thickness tα of α and the average thickness tβ of β satisfy expression: 2.0≤<tβ/tα≤6.0; and the residual stress σ of the overall hard coating layer satisfies −2.0 GPa≤σ≤−0.5 GPa.

The present invention relates to a cutting tool consisting of a hard base material, such as cemented carbide, cermet, ceramic, and cubic boron nitride, and a hard coating film formed on the hard base material. In the cutting tool according to the present invention, the hard coating film, which is composed of a monolayer or multilayer structure, is formed on a base material, wherein the hard coating film comprises a layer composed of an oxide, wherein in the layer composed of an oxide, the oxygen content of an edge center of the cutting tool is higher than the oxygen content in an area distanced from the edge center by 50 μm or more.

A coated tool in a non-limiting embodiment of the present disclosure includes a base and a coating film located on the base. The coated tool includes a first surface, a second surface adjacent to the first surface, and a cutting edge located on at least a part of a ridge part of the first surface and the second surface. The coating film includes an AlTiN film including Ti, Al and N. A first Al ratio and a second Al ratio are 0.7 or more. The first Al ratio is Al/(Al+Ti) at a point located 0.1 mm away from the cutting edge, and the second Al ratio is Al/(Al+Ti) at a point located 0.2 mm away from the cutting edge in the first surface. The second Al ratio is larger than the first Al ratio.

A coated cutting tool is provided which allows for satisfactory machining over a long period of time, particularly in the machining of difficult-to-machine materials with low thermal conductivity. The coated cutting tool includes a substrate and a coating layer formed on a surface of the substrate, wherein: at least one layer of the coating layer comprises a predetermined layer containing a compound having a composition represented by the formula: (Al.sub.XTi.sub.1-X)N [wherein x denotes an atomic ratio of the Al element based on a total of the Al element and the Ti element, and x satisfies 0.60≤x≤0.85]; a value of an orientation index TC (311) of a cubic (311) plane of the predetermined layer is from 2.5 or more to 4.2 or less; and an average thickness of the predetermined layer is from 1.0 μm or more to 12.0 μm or less.

A coated cutting tool, comprising: a substrate; and a coating layer formed on a surface of the substrate, wherein the coating layer includes a lower layer and an upper layer in this order from the substrate side toward the surface side of the coating layer, and the upper layer is formed on a surface of the lower layer, the lower layer contains a compound having a composition represented by (Al.sub.xTi.sub.1-x)N, an average thickness of the lower layer is 1.0 μm or more and 15.0 μm or less, the upper layer contains an α-Al.sub.2O.sub.3 layer containing α-Al.sub.2O.sub.3, an average thickness of the upper layer is 0.5 μm or more and 15.0 μm or less, and in the α-Al.sub.2O.sub.3 layer, a texture coefficient TC (1, 1, 6) of a (1, 1, 6) plane is 2.0 or more and 6.0 or less.

A coated tool of the present invention includes a base material and a hard coating film on the base material. The hard coating film is a nitride or carbonitride containing aluminum (Al) of 65 atomic % or more 90 atomic % or less, titanium (Ti) of 10 atomic % or more 35 atomic % or less, a total of aluminum (Al) and titanium (Ti) of 85 atomic % or more, and argon (Ar) of 0.20 atomic % or less. The hard coating film satisfies a relationship of Ih×100/Is≤12 when a peak intensity of a (010) plane of AlN of a hexagonal close-packed structure is Ih and a sum of peak intensities due to predetermined nine crystal planes of TiN and AlN is Is in an intensity profile obtained from a selected area diffraction pattern of a transmission electron microscope.

An object of the invention is to provide a coated cutting tool whose tool life can be extended by having excellent wear resistance and fracture resistance. The coated cutting tool includes: a substrate; and a coating layer formed on a surface of the substrate, in which the coating layer includes a lower layer, an intermediate layer, and an upper layer in this order from a substrate side to a surface side of the coating layer, the lower layer includes one or more Ti compound layers formed of a specific Ti compound, the intermediate layer contains TiCNO, TiCO, or TiAlCNO, the upper layer contains α-type Al.sub.2O.sub.3, an average thickness of the lower layer is 2.0 μm or more and 8.0 μm or less, an average thickness of the intermediate layer is 0.5 μm or more and 2.0 μm or less and is 10% or more and 20% or less of a thickness of the entire coating layer, an average thickness of the upper layer is 0.8 μm or more and 6.0 μm or less, and in the intermediate layer, a ratio of a length of CSL grain boundaries to a total length 100% of a total grain boundary is 20% or more and 60% or less.