A cutting tool comprising a base material and a coating, wherein the coating includes a first layer having a multilayer structure in which a first unit layer and a second unit layer are alternately stacked; a thickness of the first unit layer is 2 to 50 nm; a thickness of the second unit layer is 2 to 50 nm; a thickness of the first layer is 1.0 ?m or more and 20 ?m or less, the first unit layer is composed of Ti.sub.aAl.sub.bB.sub.cN, and the second unit layer is composed of Ti.sub.dAl.sub.eB.sub.fN, wherein 0.49?a?0.70, 0.19?b?0.40, 0.10?c?0.20, a+b+c=1.00, 0.39?d?0.60, 0.29?e?0.50, 0.10<f?0.20, d+e+f=1.00, 0.05?a-d?0.20, and 0.05?e-b?0.20 are satisfied, and a percentage of the number of atoms of titanium to the total number of atoms of titanium, aluminum and boron is 45% or more in the first layer.

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 ?m or more and 0.2 ?m 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 ?m or more and 1.2 ?m or less, an average thickness of the entire coating layer is 0.2 ?m or more and 1.3 ?m or less, and a compressive residual stress at the cubic crystal (111) plane is 3.0 GPa or less.

A coated cutting tool having excellent wear resistance and controlled brittleness is provided. An embodiment of the present disclosure provides a coated cutting tool including: a substrate; and a cutting layer disposed on the substrate, wherein: the cutting layer includes a brittleness suppressing layer and a wear-resistant layer disposed on the brittleness suppressing layer; the substrate includes a hard alloy body such as cemented carbide, cermet, ceramic, cubic boron nitride-based materials, or high-speed steel; the brittleness suppressing layer includes a first layer and a second layer disposed on the first layer; the first layer and the second layer each independently includes any one of (Al.sub.bTi.sub.1-b)X (where 0.6<b<0.8, and X is at least one selected from N, C, CN, NO, CO, and CNO) and (Ti.sub.cAl.sub.1-c)X (where 0.4<c?0.5, and X is at least one selected from N, C, CN, NO, CO, and CNO); and the first layer and the second layer include materials different from each other.

A coated cutting tool including a substrate and a coating layer formed on the substrate, wherein the coating layer has an alternately laminated structure of a first layer and a second layer, the first layer contains a compound having a composition represented by (Al.sub.aTi.sub.1-a)N (0.80?a?0.95), the second layer contains a compound having a composition represented by (Al.sub.bM.sub.cTi.sub.1-b-c)N (M represents at least one of Si or B, 0.80?b?0.95, and 0<c?0.20), a and b satisfy |a?b|?0.05, and an average thickness of the alternately laminated structure is 1.0 ?m or more and 10.0 ?m or less.

A metal drill includes a cutting section and a drive section pointing away therefrom. The metal drill has at least two different functional coatings are provided which are designed at least in regions and are designed to permit machining of a metallic workpiece adapted to a respective application material. The drive section has, at least in sections, a polygonal, preferably hexagonal cross-sectional geometry.

Provided is a surface-coated cutting tool including a base material and a coating including a super-multilayer-structure layer where A layers and B layers different from the A layers in composition are alternately laminated. The super-multilayer-structure layer includes an X area and a Y area those are alternately repeated. In the X area, A layers having a thickness A.sub.X and B layers having a thickness B.sub.X are alternately laminated. In the Y area, A layers having a thickness A.sub.Y and B layers having a thickness B.sub.Y are alternately laminated. The thickness A.sub.X is larger than the thickness A.sub.Y, and the thickness B.sub.X is smaller than the thickness B.sub.Y. Each of the A layers and the B layers comprising one or more elements selected from a group consisting of Ti, Al, Cr, Si, Ta, Nb, and W, and one or more elements selected from a group consisting of C and N.

A surface-coated cutting tool comprises a hard coating layer that includes a TiAlN layer and is provided on a surface of a cutting tool body. In case the composition of the TiAlN layer is expressed by a formula: (Ti.sub.xAl.sub.1-x)N, 0.10x0.35 (here, x is in atomic ratio) is satisfied. In the TiAlN layer, a high Ti band-like region is present in a direction at 30 degrees or less with respect to a line normal to the surface of the cutting tool body. An average composition X of the Ti component in the high Ti band-like region satisfies (x+0.01)X(x+0.05), an average width W of the high Ti band-like region is 30 to 500 nm, and an average area ratio St of the high Ti band-like region is 3 to 50 area %.

A bore cutting tool for cutting metal workpieces includes a tool substrate and a tool coating on a surface of the tool substrate. The bore cutting tool includes a plurality of pits in the surface of the tool substrate and wherein the tool coating extends over the pits such that the pit surface includes the tool coating. In this way, the pit dimensions can be retained over prolonged tool life and the pits, with their coated surface, are particularly effective at retaining lubricant so that the thickness of a lubricant film can be increased as compared to a tool without the coated pits. In the embodiments, the pits are formed by laser etching and are present only on the cylindrical land. Average pit depth is suitably in the range 8 m to 25 m, average pit width and pit length is independently selected from 40 m to 250 m and average pit density may be 20 to 30 pits/mm.sup.2.

This surface-coated cutting tool includes a cutting tool body made of tungsten carbide-based cemented carbide and a hard coating layer deposited on a surface of the cutting tool body, in which the hard coating layer has at least one (Ti.sub.1-xAl.sub.x)N layer (0.4X0.7, X is an atomic ratio) with an average layer thickness of 0.5 to 10 m, the (Ti, Al)N layer has a cubic crystal structure, and IaIb<5 is satisfied when Ia (%) is an average absorptance of the hard coating layer at a wavelength of 400 to 500 nm and Ib (%) is an average absorptance of the hard coating layer at a wavelength of 600 to 700 nm.

A hard coating comprising a lower layer formed by an fcc-based titanium aluminum nitride coating, and an upper layer formed by an aluminum nitride coating having an hcp crystal system, the upper layer having a columnar crystal structure, the columnar crystals having an average transverse cross section diameter of 0.05-0.6 m, and a ratio of an X-ray diffraction peak value Ia(002) of (002) planes to an X-ray diffraction peak value Ia(100) of (100) planes in the upper layer meeting the relation of Ia(002)/Ia(100)6.