A cutting element, which is configured for the machining of a non-metallic composite material composed of a matrix and particles held together by the matrix, has a flank face, a rake face and a cutting edge which is coated with an edge coating and via which the flank face and the rake face are connected to one another, with which the non-metallic composite material can be machined in an improved fashion. The cutting edge within a cutting edge section thereof is curved in such a way that the cutting edge immediately beneath the edge coating in a section in a section plane that is perpendicular to the cutting edge has, at every point of the cutting edge section, a local radius of curvature which is greater than or equal to 10 μm and less than or equal to 80 μm.

Provided is a NbC based cemented carbide and method of manufacture the same. The NbC based cemented carbide may be devoid of WC. The NbC based cemented carbide may be devoid of Co in the binder phase. The NbC based cemented carbide exhibits enhanced strength and thermal conductivity while maintaining desired toughness and hardness.

A composite sintered body cutting tool is made of a composite sintered body comprising a TiCN-based cermet layer; and a WC-based cemented carbide layer. The angle between the rake face and the flank face of the cutting tool is 90°. The rake face including a cutting edge of the cutting tool is constituted from the WC-based cemented carbide layer, in which 4 to 17 mass % of an iron group metal component and 75 mass % or more of W are included; and a major hard phase component is WC. The thickness of the WC-based cemented carbide layer is 0.05 to 0.3 times the thickness of the composite sintered body. The TiCN-based cermet layer is constituted from a single layer of a TiCN-based cermet layer, including at least, 4 to 25 mass % of an iron group metal component, less than 15 mass % of W, 2 to 15 mass % of Mo, 2 to 10 mass % of Nb and 0.2 to 2 mass % of Cr in a case where contents of the constituting components of the cermet layer are expressed as contents of metal components, and satisfy the Co content relative to the total content of Co and Ni of 0.5 to 0.8 with respect to Co and Ni of the iron group metal component in a mass ratio. When the height profile from the upper end to the lower end of the flank face is measured in the plane, which passes the center of the rake face of the cutting tool and is perpendicular to both of the rake face and the flank face, as the line, which passes the ridge line where the rake face and the flank face intersect and perpendicular to the rake face, being the reference line, the maximum elevation difference value of the height profile is in a ratio of 0.01 or less with respect to the thickness of the composite sintered body from the front surface of the rake face to a rear surface.

A cermet and a cutting tool are provided which have high wear resistance and high fracture resistance at a cutting edge even in a mode of cutting where the cutting edge comes to have a high temperature. A cermet 1 includes a hard phase 2 including a carbonitride of one or more kinds of metals selected from Group 4, Group 5, and Group 6 metals of the periodic table including at least Ti and a binder phase 3 containing W and at least one kind of a metal selected from Co and Ni, wherein the binder phase 3 includes a first binder phase 4 in which a mass ratio of W to a total amount of Co and Ni (W/(Co+Ni)) is 0.8 or less and a second binder phase 5 in which a mass ratio of W to a total amount of Co and Ni (W/(Co+Ni)) is 1.2 or more.

In a surface-coated cutting tool in which a hard coating layer having a total layer thickness of 0.5 to 10 μm is deposited on a surface of a tool body made of WC-based cemented carbide or TiCN-based cermet, the hard coating layer has an alternately laminated structure of A layers and B layers, in a case where the A layer is: (Al.sub.aTi.sub.1-a)N (here, a is in atomic ratio), the A layer satisfies 0.50≦a<0.75, in a case where the B layer is: (Al.sub.bTi.sub.1-b)N (here, b is in atomic ratio), the B layer satisfies 0.75≦b≦0.95, and when a layer thickness per layer of the A layers is represented by x (nm) and a layer thickness per layer of the B layers is represented by y (nm), 5y≧x≧3y and 250 (nm)≧x+y≧100 (nm) are satisfied.

A cutting insert of an embodiment includes a cutting edge located at an intersecting part of an upper surface and a side surface. The cutting edge includes a corner cutting edge, a major cutting edge, and a flat cutting edge. The upper surface includes a first land surface located along the corner cutting edge, a second land surface located along the major cutting edge, and a third land surface located along the flat cutting edge. A maximum value of a width of the third land surface is smaller than a maximum value of a width of each of the first land surface and the second land surface in a top view.

A surface-coated cutting tool has a hard coating layer on a tool body. The hard coating layer includes a (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) layer (the average amount Xavg of Al and the average amount Yavg of C satisfy 0.60≦Xavg≦0.95 and 0≦Yavg≦0.005). Crystal grains having an NaCl type face-centered cubic structure in the layer have {111} orientation, a columnar structure in which the average grain width of the individual crystal grains having an NaCl type face-centered cubic structure is 0.1 μm to 2.0 μm and the average aspect ratio is 2 to 10 is included, and in the individual crystal grains having an NaCl type face-centered cubic structure, a periodic compositional variation in Ti and Al in the composition formula: (Ti.sub.1−xAl.sub.x)(C.sub.yN.sub.1−y) is present and the difference between the average of maximum values of x and the average of minimum values thereof is 0.03 to 0.25.

Provided is a coated tool in which a hard coating layer has excellent hardness and toughness and exhibits chipping resistance and defect resistance during long-term use. The hard coating layer includes at least a layer of a complex nitride or complex carbonitride expressed by the composition formula: (Ti.sub.1-x-yAl.sub.xMe.sub.y) (C.sub.zN.sub.1-x) (here, Me is one element selected from among Si, Zr, B, V, and Cr), an average amount Xavg of Al, an average amount Yavg of Me, and an average amount Zavg of C satisfy 0.60≦Xavg, 0.005≦Yavg≦0.10, 0≦Zavg≦0.005, and 0.605≦Xavg+Yavg≦0.95, crystal grains having a cubic structure are present in crystal grains constituting the layer of a complex nitride or complex carbonitride, and in the crystal grains having a cubic structure, a predetermined periodic concentration variation of Ti, Al, and Me is present, whereby the problems are solved.

A coated cutting tool includes a substrate and a coating layer formed onto the surface of the substrate. The coating layer contains an outermost layer. The outermost layer contains NbN. The NbN contains cubic NbN and hexagonal NbN. When a peak intensity at a (200) plane of cubic NbN is made I.sub.c, a peak intensity at a (101) plane of the hexagonal NbN is made I.sub.h1, and a sum of peak intensities at a (103) plane and a (110) plane of the hexagonal NbN is made I.sub.h2 in X-ray diffraction analysis, a ratio [I.sub.h1/(I.sub.h1+I.sub.c)] of I.sub.h1 based on a sum of I.sub.c and I.sub.h1 is 0.5 or more and less than 1.0, and a ratio [I.sub.h1/(I.sub.h1+I.sub.h2)] of I.sub.h1 based on a sum of I.sub.h1 and I.sub.h2 is 0.5 or more and 1.0 or less.

A coated cutting tool has a substrate and a coating layer formed onto a surface of the substrate. The coating layer contains a hard layer of a composition represented by (Ti.sub.xM.sub.1-x)N, wherein M represents at least one kind of an element selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si and Y, and x represents an atomic ratio of a Ti element based on a sum of the Ti element and an M element, and satisfies 0.45≦x≦0.9. Also, an average grain size of grains constituting the hard layer is 200 nm or more and 600 nm or less, and the grains of the hard layer satisfy predetermined conditions.