Coated Cutting Tools

Abstract

The present invention relates to a coated cutting tool and a method for producing the same, the coated cutting tool comprising a substrate body of a WC-Co based cemented carbide and a coating, the coating including a first (Ti,Al)N multilayer, a first gamma-aluminum oxide layer, and a set of alternating second (Ti,Al)N multilayers and second gamma-aluminum oxide layers.

Description

[Technical Field]

[0001] The present invention relates to a coated cutting tool comprising a substrate body of cemented carbide and a wear-resistant coating applied to the substrate. The present invention further relates to a method for manufacturing such a coated cutting tool. [Background technology]

[0002] Cutting tools for metal cutting generally consist of a substrate body made of cemented carbide with a wear-resistant coating of a combination of various layers deposited on the substrate by CVD (chemical vapor deposition) or PVD (physical vapor deposition) processes. In this regard, cutting tools generally have a rake face, a flank face, and a cutting edge therebetween. The shape and geometry of the cutting tool depend on the intended metal cutting operation. Examples of cutting tools are milling inserts, turning inserts, drills, and end mills.

[0003] There are various different types of PVD processes that result in different coating properties, such as cathode sputtering, cathodic vacuum arc evaporation, and ion plating. Cathode sputtering, such as magnetron sputtering, reactive magnetron sputtering, and high-power impulse magnetron sputtering (HIPIMS), as well as arc evaporation, are among the PVD processes most frequently used for coating cutting tools.

[0004] The various wear processes on a tool eventually reduce its performance and require its replacement. Therefore, when preparing a coated cutting tool for metal cutting, a primary goal is that the tool must be usable for as long as possible, i.e., have as long a tool life as possible. It must also be possible to use high cutting speeds in the cutting operation. Because high cutting speeds generate a lot of heat, this means, for example, that the cutting tool, and in particular the coating, must be highly heat-resistant. Summary of the Invention

[0005] It is an object of the present invention to provide a coated cutting tool that has high wear resistance in general and provides long tool life in metal machining operations such as milling, turning and drilling, particularly in milling steels. The coated cutting tool of the present invention should also allow for rigorous surface treatment without the coating peeling off.

[0006] invention The present invention relates to a coated cutting tool comprising a substrate body and a coating, wherein the substrate body is a WC-Co based cemented carbide body containing 5 to 15 wt % Co, and the coating comprises, in order from the substrate surface, a first (Ti,Al)N multilayer, which is a multilayer of alternating (Ti,Al)N sublayers, - the total atomic ratio of Ti:Al in the first (Ti,Al)N multilayer is 33:67 to 67:33; - the total thickness of the first (Ti,Al)N multilayer is 1-8 μm; - each of the individual (Ti,Al)N sublayers in the first (Ti,Al)N multilayer has a thickness of 1 to 25 nm; - each individual (Ti,Al)N sublayer within the first (Ti,Al)N multilayer differs from the immediately adjacent (Ti,Al)N sublayer in terms of the atomic ratio Ti:Al; the first (Ti,Al)N multilayer comprises two or more (Ti,Al)N sublayer stacks arranged directly above one another, wherein at least two individual (Ti,Al)N sublayers are present within the same (Ti,Al)N sublayer stack, the at least two individual (Ti,Al)N sublayers having different Ti:Al atomic ratios, and the total Al content within each of the (Ti,Al)N sublayer stacks increases from one (Ti,Al)N sublayer stack to the next in a direction toward the outer surface of the coating; a first gamma-aluminum oxide layer (wherein -The thickness of the first gamma-aluminum oxide layer is 0.3 to 1.5 μm and a set of alternating second (Ti,Al)N multilayers and second gamma-aluminum oxide layers, where - the number of each of the second (Ti,Al)N multilayers and the second gamma-aluminum oxide layers (10) is greater than or equal to 2; each second (Ti,Al)N multilayer is a multilayer of alternating (Ti,Al)N sublayers, - the total atomic ratio of Ti:Al in the second (Ti,Al)N multilayer is in the range of 33:67 to 67:33; - the thickness of each of the second (Ti,Al)N multilayers is 0.05-0.5 μm; each of the individual (Ti,Al)N sublayers within the second (Ti,Al)N multilayer has a thickness in the range of 1 to 25 nm, preferably 2 to 10 nm; - each individual (Ti,Al)N sublayer within the second (Ti,Al)N multilayer differs from the immediately adjacent (Ti,Al)N sublayer in terms of the atomic ratio Ti:Al; - the thickness of each of the second gamma-aluminum oxide layers is 0.05 to 0.5 μm) The total thickness of the entire coating of the coated cutting tool is 3 to 15 μm.

[0007] In one embodiment, the surface zone of the substrate body exhibits a residual compressive stress of at least 0.5 GPa, preferably at least 0.8 GPa, most preferably 1-2 GPa.

[0008] In this specification, the surface zone of the substrate body means the topmost part of the substrate body, which is the distance from the surface of the substrate body through which the X-rays used in the residual stress measurement method penetrate.

[0009] Preferably, the increase in total Al content within each of the (Ti,Al)N sublayer stacks from one (Ti,Al)N sublayer stack to the next in a direction toward the outer surface of the first (Ti,Al)N multilayer coating comprises the atomic ratio Ti:Al across several pairs of adjacent (Ti,Al)N sublayers remaining constant across several pairs of adjacent (Ti,Al)N sublayers of one sublayer stack, and then the atomic ratio Ti:Al decreasing by a substantial amount in the next several pairs of adjacent (Ti,Al)N sublayers of the further sublayer stack.

[0010] Suitably, there are 2 to 5, preferably 2 to 4, most preferably 2 individual (Ti,Al)N sublayers within the same (Ti,Al)N sublayer stack of the first (Ti,Al)N layer, and different individual (Ti,Al)N sublayers have different Ti:Al atomic ratios.

[0011] The total atomic ratio of Ti:Al in the first (Ti,Al)N multilayer is suitably between 33:67 and 50:50, preferably between 35:65 and 45:55.

[0012] If the individual (Ti,Al)N sublayers of the first (Ti,Al)N multilayer are very thin, there may not be a sharp boundary between two adjacent sublayers with different Ti:Al ratios. Instead, the Ti:Al ratio may vary gradually over the thickness of the (Ti,Al)N multilayer in a periodic manner. For this reason, the Ti:Al ratio of a sublayer is herein considered to be the Ti:Al ratio present midway through the sublayer.

[0013] In one embodiment, the atomic ratio Ti:Al of the individual (Ti,Al)N sublayer type of the first (Ti,Al)N multilayer having the highest Al content among the individual (Ti,Al)N sublayer types is 20:80 to 60:40, preferably 25:75 to 50:50, and most preferably 30:70 to 40:60.

[0014] In one embodiment, the atomic ratio Ti:Al of the individual (Ti,Al)N sublayer type of the first (Ti,Al)N multilayer having the lowest Al content among the individual (Ti,Al)N sublayer types is 35:65 to 80:20, preferably 40:60 to 65:35, and most preferably 45:55 to 55:45.

[0015] In one embodiment, there are 2 to 5, preferably 2 to 3, and most preferably 2 different types of individual (Ti,Al)N sublayers within the same (Ti,Al)N sublayer stack of the first (Ti,Al)N multilayer, and the same type of (Ti,Al)N sublayers have the same composition in terms of Ti:Al atomic ratio, and the different types of individual (Ti,Al)N sublayers have different Ti:Al atomic ratios.

[0016] Preferably, each individual (Ti,Al)N sublayer in the first (Ti,Al)N multilayer of alternating (Ti,Al)N sublayers has a thickness of 2 to 10 nm.

[0017] The total thickness of the first (Ti,Al)N multilayer is preferably 2-7 μm. In one embodiment, particularly suitable for milling applications, the total thickness of the first (Ti,Al)N multilayer is 2-5 μm. In another embodiment, particularly suitable for turning applications, the total thickness of the first (Ti,Al)N multilayer is 5-7 μm.

[0018] In one embodiment, the thickness of each (Ti,Al)N sub-layer stack of the first (Ti,Al)N layer is between 0.5 and 5 μm, suitably between 1 and 3.5 μm, preferably between 1 and 2.5 μm.

[0019] Suitably, the first (Ti,Al)N multilayer consists of a stack of 2 to 5, preferably 2 to 3, most preferably 2 (Ti,Al)N sublayers arranged directly above each other.

[0020] In one embodiment, the first (Ti,Al)N multilayer has a Vickers hardness HV 0.0015 of at least 2800, preferably at least 3000. The upper limit of Vickers hardness HV 0.0015 is suitably at most 3500.

[0021] In one embodiment, the first (Ti,Al)N multilayer has a reduced Young's modulus greater than 350 GPa, preferably greater than 400 GPa, more preferably greater than 420 GPa. The upper limit of the reduced Young's modulus is suitably up to 520 GPa.

[0022] In one embodiment of the present invention, the first (Ti,Al)N multilayer is deposited directly on the substrate surface, ie, the (Ti,Al)N multilayer is in direct contact with the substrate surface and has a contact surface with the substrate surface.

[0023] In one embodiment, a residual compressive stress of 0.5 to 2 GPa, preferably 0.8 to 1.5 GPa, is present within a portion of the first (Ti,Al)N multilayer that is at least 100 nm and at most 1 μm thick from the interface of the (Ti,Al)N multilayers that is disposed in a direction toward the substrate body.

[0024] The residual stress in the first (Ti,Al)N multilayer is calculated as sin 2 Residual stress is suitably measured by X-ray diffraction using the Ψ method. Because XRD always measures over a certain penetration depth into the layer material, it is not possible to measure the residual stress of a first (Ti,Al)N multilayer only at its exact interface with the substrate or the layer immediately below it. Therefore, within the meaning of the present invention, residual stress is measured within a section of the first (Ti,Al)N multilayer that is at least 100 nm thick and up to 1 μm thick, preferably up to 750 nm thick, more preferably up to 500 nm thick, and most preferably up to 250 nm thick, from the interface of the (Ti,Al)N multilayer in the direction toward the substrate. Residual stress within the first 100 nm thick and up to 1 μm thick from the interface can be measured by removing the coating material above the first (Ti,Al)N multilayer and then further removing the coating material so that the thickness of the (Ti,Al)N multilayer decreases. Care must be taken to select and apply a material removal method that does not significantly change the residual stress in the remaining (Ti,Al)N multilayer material. A suitable method for removing the deposited coating material may be polishing, but gentle and slow polishing using fine-grained abrasives should be applied. As is known in the art, aggressive polishing using coarse-grained abrasives will actually increase compressive residual stress. Other suitable methods for removing the deposited coating material are ion etching and laser ablation.

[0025] In one embodiment, the difference between the absolute values ​​of the residual stresses in (i) a portion of at least 100 nm and at most 1 μm thick in the first (Ti,Al)N multilayer from the contact surface of the (Ti,Al)N multilayer arranged in the direction towards the substrate body, and (ii) in the surface zone of the substrate body, is 400 MPa or less, preferably 200 MPa or less.

[0026] The difference in the overall Al content between the (Ti,Al)N sublayer stack can be achieved in several ways, individually or in combination. For example, an increase in Al content can be achieved by selecting the type and number of targets containing specific amounts of Al and Ti during the deposition process. Furthermore, the Al and Ti content of the deposited coating layer can be varied by changing deposition conditions such as bias and arc current.

[0027] Also, increasing the Al content through the thickness of the first (Ti,Al)N multilayer can be achieved by increasing the thickness of the individual (Ti,Al)N sublayers having higher Al contents over the thickness of the individual (Ti,Al)N sublayers having lower Al contents.

[0028] Increasing the Al content through the thickness of the first (Ti,Al)N multilayer can result in different residual stresses between portions of the (Ti,Al)N multilayer, and the residual stress within the first (Ti,Al)N multilayer can be influenced by changing deposition conditions such as bias and arc current.

[0029] Suitably, the thickness of the first gamma-aluminum oxide layer is between 0.4 and 1 μm, preferably between 0.5 and 0.8 μm.

[0030] The total atomic ratio of Ti:Al in the second (Ti,Al)N multilayer is suitably between 33:67 and 50:50, preferably between 35:65 and 45:55.

[0031] Preferably, each of the second (Ti,Al)N multilayers has a thickness of 0.1 to 0.4 μm.

[0032] In one embodiment, the second (Ti,Al)N multilayer comprises 2-5, preferably 2-4, and most preferably 2, types of individual (Ti,Al)N sublayers, with different types of individual (Ti,Al)N sublayers having different Ti:Al atomic ratios.

[0033] Preferably, each individual (Ti,Al)N sublayer within the second (Ti,Al)N multilayer of alternating (Ti,Al)N sublayers has a thickness of 2 to 10 nm.

[0034] If the individual (Ti,Al)N sublayers of the second (Ti,Al)N multilayer are very thin, there may not be a sharp boundary between two adjacent sublayers with different Ti:Al ratios. Instead, the Ti:Al ratio may vary gradually over the thickness of the (Ti,Al)N multilayer in a periodic manner. For this reason, the Ti:Al ratio of a sublayer is herein considered to be the Ti:Al ratio present midway through the sublayer.

[0035] In one embodiment, the atomic ratio Ti:Al of the individual (Ti,Al)N sublayer type of the second (Ti,Al)N multilayer having the highest Al content among the individual (Ti,Al)N sublayer types is 20:80 to 60:40, preferably 25:75 to 50:50, and most preferably 30:70 to 40:60.

[0036] In one embodiment, the atomic ratio Ti:Al of the individual (Ti,Al)N sublayer type of the second (Ti,Al)N multilayer having the lowest Al content of the individual (Ti,Al)N sublayer types is 35:65 to 80:20, preferably 40:60 to 65:35, and most preferably 45:55 to 55:45.

[0037] Preferably, all second (Ti,Al)N multilayers are the same, ie, they have substantially the same overall Ti:Al atomic ratio and Ti:Al atomic ratios of their sublayers.

[0038] In one embodiment, each of the second (Ti,Al)N multilayers has the same alternating sublayers and sublayer composition as the outermost sublayer stack of the (Ti,Al)N sublayer stack of the first (Ti,Al)N multilayer. The reasons for this are both practical and technical. Because higher aluminum content has been shown to correlate with better wear resistance, there are advantages to maintaining a relatively high aluminum content in the outermost sublayer stack of the first (Ti,Al)N multilayer. Also, increasing the aluminum content of the first (Ti,Al)N layer by adding additional targets with higher aluminum content in the PVD chamber increases the deposition rate, which is advantageous.

[0039] The number of second (Ti,Al)N multilayers and second gamma-aluminum oxide layers is preferably 2 to 20, more preferably 2 to 10, and most preferably 2 to 6. It is believed that using a higher number, i.e., a higher number of repetitions, introduces greater toughness into the coating and also results in lower thermal conductivity due to the increased number of grain boundaries. However, if the number is too high, the complexity of producing the coating increases because the process must be repeatedly switched between producing (Ti,Al)N multilayers and aluminum oxide. This also increases production time. Therefore, it is preferable to limit the number of repetitions so that a sufficient technical effect can be achieved with reasonable complexity and production time.

[0040] Preferably, the thickness of each of the second gamma-aluminum oxide layers is 0.1 to 0.3 μm.

[0041] In a preferred embodiment of the coated cutting tool of the present invention, the alternating (Ti,Al)N sublayers of the first and second (Ti,Al)N multilayers of the coating are deposited by cathodic arc evaporation.

[0042] In one embodiment, the Vickers hardness HV0.0015 of the first gamma-aluminum oxide layer, and preferably both the first and second gamma-aluminum oxide layers, is 3000-3500 HV0.0015.

[0043] In one embodiment, the reduced Young's modulus of the first gamma-aluminum oxide layer, and preferably both the first and second gamma-aluminum oxide layers, is between 350 and 390 GPa.

[0044] In one embodiment, the coating includes a metal nitride layer as an outermost layer, the metal belonging to Group 4, 5, or 6 of the Periodic Table of Elements, preferably Zr, Ti, or Cr, and having a thickness of 0.01 to 1 μm, preferably 0.05 to 0.5 μm. The function of this outermost layer is one or more of wear indication, decoration, and diffusion barrier to the workpiece material. Preferably, the outermost layer is a ZrN layer.

[0045] The total coating thickness of the coated cutting tool is preferably 3-10 μm. The ideal thickness depends on the metal cutting application. In one embodiment, the total coating thickness of the coated cutting tool is 3.5-6 μm, particularly suitable for milling applications. In another embodiment, the total coating thickness of the coated cutting tool is 6-8 μm, particularly suitable for turning applications. In another embodiment, the total coating thickness of the coated cutting tool is 3-5 μm, particularly suitable for drilling applications.

[0046] The substrate of the coated cutting tool of the present invention is a WC-Co based cemented carbide containing 5 to 15 wt. % Co. The substrate optionally contains additional cubic carbides or carbonitrides, as is generally known in the art.

[0047] In one embodiment, the substrate is a cemented carbide with a composition of 86-90 wt% WC, 0.2-0.8 wt% Cr, and 11-13 wt% Co, totaling 100 wt%. The WC grain size is less than 1 μm, preferably 0.2-0.6 μm.

[0048] In one embodiment, the substrate is a cemented carbide with a composition of 86-90 wt% WC, 0.5-2 wt% (Ta,Nb)C, and 8-13 wt% Co, totaling 100 wt%. The WC grain size is less than 1.5 μm, preferably 0.5-1.2 μm.

[0049] The WC grain size is determined herein from the magnetic coercivity value. The relationship between WC coercivity and grain size is described, for example, in Roebuck et al., Measurement Good Practice No. 20, National Physical Laboratory, ISSN 1368-6550, November 1999, revised February 2009, section 3.4.3, pages 19-20. For the purposes of the present application, the WC grain size d is determined according to equation (8) on page 20 of the above publication: K=(c1+d1W Co )+(c2+d2W Co ) / d. The sorting is as follows: d=(c2+d2W Co ) / (K-(c1+d1W Co ))、 where d = WC grain size of the cemented carbide body, K = coercive force (kA / m) of the cemented carbide body (here measured according to the DIN IEC 60404-7 standard), W Co = wt% Co in the cemented carbide body, c1 = 1.44, c2 = 12.47, d1 = 0.04, and d2 = -0.37.

[0050] The top portion of the substrate in contact with the coating is preferably substantially free of damaged WC particles, i.e., WC particles that have been cracked into smaller parts. This lack of damaged WC particles results from a specific pretreatment ion etching procedure performed on the substrate prior to deposition of the coating.

[0051] The coated cutting tool is suitably a milling insert, a turning insert, a drilling insert, a drill or an end mill, preferably a milling insert or a turning insert.

[0052] The present invention provides a method for producing a coated cutting tool comprising a substrate body and a deposited coating, the method comprising: providing a substrate body, which is a WC-Co based cemented carbide body containing 5 to 15 wt. % Co; - subjecting the surface of the substrate body to a pretreatment, which is an ion etching procedure, so that a thickness of at least 0.5 μm of the substrate body is removed; depositing a first TiAlN multilayer, a 1-8 μm thick layer, by cathodic arc evaporation PVD using at least two TiAl targets with different Ti:Al atomic ratios in a chamber containing nitrogen gas at a pressure of -5 to 15 Pa, preferably 7 to 12 Pa, using a bias voltage of -20 to -80 V, preferably -35 to -65 V, and an applied arc current of 50 to 200 A, preferably 100 to 150 A, wherein the (Ti,Al)N multilayer is a multilayer of alternating (Ti,Al)N sublayers, the atomic Ti:Al ratio of the targets being selected such that the total atomic ratio of Ti:Al is between 33:67 and 67:33, and each of the individual (Ti,Al)N sublayers is 1 depositing a (Ti,Al)N multilayer having a thickness in the range of about 25 nm, wherein each individual (Ti,Al)N sublayer differs from its immediately adjacent (Ti,Al)N sublayer with respect to its atomic ratio of Ti:Al, wherein the (Ti,Al)N multilayer is deposited to include two or more (Ti,Al)N sublayer stacks disposed directly above one another, wherein at least two individual (Ti,Al)N sublayers are present within the same (Ti,Al)N sublayer stack, the at least two individual (Ti,Al)N sublayers having different Ti:Al atomic ratios, and wherein the total Al content within each (Ti,Al)N sublayer stack increases from one (Ti,Al)N sublayer stack to the next in a direction toward an outer surface of the first (Ti,Al)N multilayer; -1 to 5 Pa total gas pressure, 0.001 to 0.1 Pa oxygen partial pressure, 4 to 20 W / cm at temperatures of 400 to 600°C 2depositing a first gamma-aluminum oxide layer having a thickness of 0.3 to 1.5 μm by reactive magnetron sputtering PVD using at least one Al target in an oxygen-containing gas volume using a magnetron power density of 0.3 μm to 1.5 μm, a bias voltage of 80 to 200 V, and a pulsed bias current of 20 to 60 A; - depositing a set of alternating second (Ti,Al)N multilayers and second gamma-aluminum oxide layers, the second (Ti,Al)N multilayers and the second gamma-aluminum oxide layers being deposited using the same process conditions as when depositing the first (Ti,Al)N multilayers and the first gamma-aluminum oxide layers, respectively, the number of each second (Ti,Al)N multilayers and second gamma-aluminum oxide layers being equal to or greater than two, and each second (Ti,Al)N multilayer being a multilayer of alternating (Ti,Al)N sublayers. a total atomic ratio of Ti:Al in the second (Ti,Al)N multilayer is between 33:67 and 67:33; a thickness of the second (Ti,Al)N multilayer is between 0.05 and 0.5 μm; each of the individual (Ti,Al)N sublayers in the second (Ti,Al)N multilayer has a thickness between 1 and 25 nm; each of the individual (Ti,Al)N sublayers in the second (Ti,Al)N multilayer differs from its immediately adjacent (Ti,Al)N sublayer with respect to its atomic ratio of Ti:Al; and a thickness of the second gamma-aluminum oxide layer is between 0.05 and 0.5 μm. and the total thickness of the entire deposited coating of the coated cutting tool is 3 to 15 μm; - subjecting the deposited coating to a first post-treatment procedure comprising shot peening using zirconium oxide based ceramic beads so that a compressive stress of at least 0.5 GPa is induced in the surface zone of the substrate body; - subjecting the deposited coating to a second post-treatment step by wet blasting with a slurry of aluminum oxide particles; The method further includes a method of production comprising:

[0053] In one embodiment, after deposition of the set of alternating layers of the second (Ti,Al)N multilayer and the second gamma-aluminum oxide layer, there is an outermost layer deposited before the first post-treatment step, the outermost layer being a metal nitride layer, wherein the metal belongs to group 4, 5, or 6 of the periodic table of the elements, preferably Zr, Ti, or Cr.

[0054] In the deposition of the gamma-aluminum oxide layer, the power density in the magnetron is preferably 6 to 13 W / cm 2 is.

[0055] In the deposition of the gamma-aluminum oxide layer, the pulsed bias voltage is preferably 100 to 180 V. The pulsed bias voltage can be either unipolar or bipolar.

[0056] During the initial processing of the cemented carbide body, such as edge rounding, blasting or grinding, which is performed prior to ion etching, damaged WC particles are typically present on the substrate surface, which can crack into smaller parts, forming spots on the substrate surface where, for example, the deposited coating loses adhesion to the substrate and leads to spalling.

[0057] The pretreatment of the cemented carbide body by ion etching prior to the deposition of the coating is carried out to reduce or completely remove WC particles that have been damaged or mechanically refined during previous processing of the cemented carbide body. The ion etching suitably removes at least 0.8 μm of the cemented carbide body, preferably at least 1 μm, and most preferably at least 1.5 μm. These removal levels are found at least in the region close to the cutting edge, i.e., within a distance of up to 500 μm from the cutting edge. The ion etching procedure preferably includes removing substantially all damaged WC particles from the cemented carbide body surface.

[0058] Furthermore, in addition to removing damaged particles, the ion etching procedure of the cemented carbide body reduces the amount of residual stress at the substrate surface that may have been induced by any previous treatment, since the top layer containing such induced residual stresses is actually partially or completely removed, thereby improving coating adhesion.

[0059] Preferably, argon ion etching is the ion etchant used. The ion etching process is carried out for a sufficient time to achieve the desired removal of damaging particles.

[0060] "Shot peening" as used herein refers to impact with a medium containing non-abrasive, typically rounded particles, called beads. Shot peening, as used herein, is a dry blasting process in which no liquid is used with the beads. The beads, as used herein, are made from a zirconium oxide-based ceramic. By zirconium oxide-based, as used herein, it is meant that the weight percent of zirconium oxide in the beads is greater than 50 weight percent. The beads may further contain other oxides, such as silicon oxide and / or aluminum oxide.

[0061] The shot peening suitably induces a residual compressive stress in the surface zone of the substrate body of at least 0.5 GPa, preferably at least 0.8 GPa, most preferably 1-2 GPa.

[0062] Preferably, the shot peening beads are within the size range of 50 to 175 μm, preferably 70 to 125 μm. The impact or energy from the beads during shot peening should not be too high, as this increases the risk of damaging the coating and even resulting in coating peeling. The impact or energy from the beads should not be too low, as this will prevent the technical effect from being achieved. If the beads are too large, there is a high risk of significant damage to the coating. On the other hand, if the beads are too small, the energy and impact transferred from the beads to the substrate will be too small. The appropriate size of the beads should be selected by those skilled in the art.

[0063] Shot peening uses a blast gun where beads exit a blast nozzle. In one embodiment, shot peening is carried out using a blast pressure of 1 to 8 bar, preferably 3 to 6 bar. The blast pressure is the exit pressure from the nozzle.

[0064] In one embodiment, the working time for shot peening is 2 to 60 seconds, preferably 2 to 10 seconds.

[0065] In one embodiment, the distance between the blast nozzle and the surface of the coated cutting tool is 50 to 200 mm, preferably 75 to 150 mm.

[0066] In one embodiment, the shot peening is performed with the shot direction at an angle of 75 to 90 degrees relative to the surface of the coated cutting tool, preferably substantially perpendicular to the surface of the coated cutting tool.

[0067] In one embodiment, the shot peening beads are within a size range of 70 to 125 μm, the shot peening is performed using a blasting pressure of 3 to 6 bar, the shot peening operation time is 2 to 10 seconds, the distance between the blast nozzle and the surface of the coated cutting tool is 75 to 150 mm, and the shot peening is performed with a shot direction substantially perpendicular to the surface of the coated cutting tool.

[0068] "Wet blasting" herein refers to a blasting process using a medium containing abrasive particles, here aluminum oxide, in a liquid forming a slurry, where material is typically removed to some extent resulting in a smoother surface of the coating, and some residual compressive stress is introduced into the coating.

[0069] In one embodiment, wet blasting is carried out until a residual compressive stress is induced in the coating of at least 0.2 GPa, preferably at least 0.5 GPa, and most preferably at least 1 GPa, when averaged across the thickness of the coating.

[0070] Wet blasting uses a blast gun where the slurry exits a blast nozzle. In one embodiment, wet blasting is carried out using a blast pressure of 1.5 to 2 bar. The wet blast pressure is the outlet pressure from the nozzle.

[0071] In one embodiment, the concentration of aluminum oxide particles in the slurry is 15 to 20% by volume.

[0072] For example, for abrasive grains used in blasting, there is an established standard - FEPA (Federation of European Producers of Abrasives) - that defines the particle size. In one embodiment, the aluminum oxide particles used for wet blasting belong to one or more of the FEPA designations F240, F280 and F320, preferably F280 and F320.

[0073] In one embodiment, the blasting time in wet blasting is 2 to 60 seconds, preferably 2 to 30 seconds, and most preferably 2 to 10 seconds.

[0074] In one embodiment, the distance between the blast gun nozzle and the surface of the coated cutting tool is 50 to 200 mm, preferably 75 to 150 mm.

[0075] In one embodiment, the wet blasting is carried out with a blasting direction at an angle of 60 to 90 degrees, preferably 75 to 90 degrees, relative to the surface of the coated cutting tool.

[0076] In one embodiment, the second post-treatment step includes wet blasting using a blasting pressure of 1.5 to 2 bar, the concentration of aluminum oxide particles in the slurry is 15 to 20 volume %, the aluminum oxide particles used for wet blasting belong to one or more of FEPA designations F240, F280, and F320, the blasting time in wet blasting is 2 to 60 seconds, the distance between the blast gun nozzle and the surface of the coated cutting tool (1) is 50 to 200 mm, and the wet blasting is performed with a blasting direction at an angle of 60 to 90 degrees relative to the surface of the coated cutting tool.

[0077] method XRD (X-ray diffraction) XRD measurements were performed on a GE Sensing and Inspection Technologies XRD3003 PTS diffractometer using CuKα radiation. The X-ray tube was operated at 40 kV and 40 mA in point focus. Parallel beam optics using a polycapillary collimating lens with a fixed size measurement aperture was used on the primary side, thereby defining the irradiation area of ​​the sample to avoid spillover of the X-ray beam on the coated surface of the sample. On the secondary side, a Soller slit with a divergence of 0.4° and a 25 μm thick Ni K β A filter was used. Measurements were performed over the 2θ range of 15 to 80° with a step size of 0.03°. To study the crystalline structure of the layers, a grazing incidence X-ray diffraction technique under a 1° incidence angel was used.

[0078] residual stress Residual stress is sin 2Measured by XRD using the Ψ method (see ME Fitzpatrick, ATFry, P. Holdway, FA Kandil, J. Shackleton and L. Suominen - A Measurement Good Practice Guide No. 52; "Determination of Residual Stresses by X-ray Diffraction - Issue 2", 2005).

[0079] The side gradient method (Ψ geometry) is the selected sin 2 Eight equidistant Ψ angles within the Ψ range were used. An equidistant distribution of Φ angles within a 90° sector is preferred. Measurements were performed on the rake face of the tool, i.e., on the flattest possible surface. A Poisson's ratio of 0.20 and a Young's modulus E of 450 GPa were applied to calculate residual stress values. For measurements on the (Ti,Al)N layer, commercially available software (RayfleX version 2.503) was used to evaluate the data and identify the (1 1 1) reflection of (Ti,Al)N using a pseudo-Voight fit function. Depending on the diffraction pattern, other reflections, such as the (2 0 0) reflection, are also possible, provided there is sufficient signal intensity.

[0080] For measurements on cemented carbide substrates, commercially available software (RayfleX version 2.503) was used to evaluate the data and identify the location of the WC (2 1 1) reflection with a pseudo-Voigt fit function. The coating generally does not need to be removed.

[0081] To measure the residual stress of a layer of a coating that has further layers deposited on it, the material above the layer being measured is removed. This also applies to measurements on cemented carbide substrates on which the coating is deposited. Care must be taken to select and apply a material removal method that does not significantly alter the residual stress within the remaining (Ti,Al)N multilayer material. A suitable method for removing the deposited coating material may be grinding, but gentle, slow grinding using fine-grained abrasives should be applied. As is known in the art, aggressive grinding using coarse-grained abrasives can actually increase compressive residual stress. Other suitable methods for removing deposited coating material are ion etching and laser ablation.

[0082] Hardness / Young's Modulus Hardness and reduced Young's modulus measurements were performed by nanoindentation using a Fischerscope® HM500 Picodentor (Helmut Fischer GmbH, Sindelfingen, Germany) with the Oliver and Pharr evaluation algorithm. Vickers diamond specimens were pressed into the layers, and force-path curves were recorded during the measurements (maximum load: 15 mN; load / unload time: 20 s; creep time: 5 s). From this curve, hardness and reduced Young's modulus were calculated.

[0083] Measurements are usually taken from the top of the layer perpendicular to the surface plane. However, in the case of multi-layer structures, cut surfaces can be made and the hardness measured in a direction along the surface plane. Furthermore, in the case of thin layers, angle polishing can be performed to provide an inclined surface on which the hardness can be measured. [Brief explanation of the drawings]

[0084] [Figure 1] 1 shows a schematic diagram of an embodiment of a cutting tool that is a milling insert. [Figure 2]1 shows a schematic diagram of a cross section of one embodiment of a coated cutting tool of the present invention showing a substrate and a coating comprising various layers. DETAILED DESCRIPTION OF THE INVENTION

[0085] Figure 1 shows a schematic diagram of one embodiment of a cutting tool (1) having a rake face (2), a flank face (3), and a cutting edge (4). The cutting tool (1) is a milling insert in this embodiment. Figure 2 shows a schematic diagram of a cross section of one embodiment of a coated cutting tool of the present invention, having a substrate body (5) and a coating (6). The coating consists of a first (Ti,Al)N multilayer (7), a first gamma aluminum oxide layer (8), an alternating set of a second (Ti,Al)N multilayer (9) and a second gamma aluminum oxide layer (10), and an outermost layer (11) that is a ZrN layer. [Example]

[0086] Example 1: Preparation of samples according to the present invention As substrates, cutting tool bodies (called "blanks") were used which were inserts with geometries ADMT160608R-F56, ODHT050408-F57 and P2808.1, all geometries used in milling operations.

[0087] For samples S1 to S4, the cutting tool body was composed of a cemented carbide with a composition of 88 wt% WC, 1.5 wt% (Ta, Nb)C, and a binder phase of 10.5 wt% Co. The average WC grain size dWC was 0.8 μm.

[0088] For samples S5 and S6, the cutting tool body was composed of a cemented carbide with a composition of 87.5 wt% WC and 0.5 wt% Cr, and a binder phase of 12.5 wt% Co. The average WC grain size dWC was 0.4 μm.

[0089] Prior to deposition, the substrate body was pretreated by ultrasonic cleaning in an aqueous medium.

[0090] 8 x 10 PVD reactors-5 The blank was evacuated to 1000 mbar and the substrate was pretreated at 550 °C. The pretreatment included an Ar ion etching procedure carried out to remove a thickness of about 0.8 μm of the substrate, thereby removing all carbide particles that had been damaged (cracked) during previous processing of the blank, such as edge rounding.

[0091] The coating equipment used to deposit the coating according to the invention was 1 m 3 The test piece was a Hauzer HTC1000 (IHI Hauzer Techno Coating BV, The Netherlands) with a chamber size of 1000 mm.

[0092] Deposition of the first (Ti,Al)N multilayer: The deposition of the first (Ti,Al)N multilayer was performed using cathodic arc evaporation. The Hauzer HTC1000 system used employed the circular arc PVD technique (CARC+) with a constant magnetic field configuration during deposition.

[0093] For the deposition of the first (Ti,Al)N multilayer, two TiAl targets with different Ti:Al atomic ratios were used to create alternating (Ti,Al)N sublayers. The Ti:Al atomic ratios of the two TiAl targets were "Ti50Al50" (Ti:Al = 50:50) and "Ti33Al67" (Ti:Al = 33:67), respectively.

[0094] When a target of a particular composition is referred to herein, this means that, depending on the layout of the PVD reactor used, a line of four targets of the same composition are arranged vertically to allow uniform deposition across the height of the reactor.

[0095] The target had a diameter of 100 mm. The reactive gas for nitride deposition was N2. Two (Ti,Al)N sublayer stacks, L1 and L2, were prepared. To prepare the coating of the present invention, L1 was deposited directly on the substrate surface, and L2 was deposited directly on L1. However, to investigate the (Ti,Al)N sublayer stacks L1 and L2 independently, samples were prepared in which only L1 and only L2 were deposited directly on the substrate surface. Two targets were used for the deposition of L1: 1× "Ti50Al50" + 1× "Ti33Al67". To achieve a lower Ti content and a higher Al content in L2, three targets were used for the deposition of L2: 1× "Ti50Al50" + 2× "Ti33Al67". Deposition was performed with an arc current of approximately 150 A for each target. Different samples were fabricated using different bias levels: −40 V and −60 V for L1, respectively, and −40 V and −50 V for L2, respectively. Further processing parameters for the deposition of the various layers are listed in Table 1. TIFF0007728261000001.tif75170

[0096] The thicknesses of the sublayer stacks L1 and L2 for the samples made using a bias level of -40V were measured at both the rake and flank edges (at the beginning of the edge rounding) and averaged to approximately 2 μm each.

[0097] The thicknesses of the sublayer stacks L1 and L2 for the samples fabricated using bias levels of -60V (L1) and -50V (L2) were measured at both the rake and flank edges (at the beginning of the edge rounding) and averaged approximately 1.5 μm each. Table 2 summarizes the samples fabricated. TIFF0007728261000002.tif142170

[0098] The deposition time for L1 was 90 minutes when deposited using −40 V (samples S1, S3, and S5). L1 therefore consisted of approximately 270 sublayer periods, approaching an individual sublayer thickness of approximately 4 nm.

[0099] When L1 was deposited using −60 V (samples S2, S4, and S6), the deposition time of L1 was 63 min. L1 therefore consisted of approximately 190 sublayer periods, approaching an individual sublayer thickness of approximately 4 nm.

[0100] The deposition time of L2 was 60 min when deposited using -40 V (samples S1, S3, and S5). L2 therefore consisted of approximately 180 sublayer periods and had the approximate composition Ti 0.50 Al 0.50 For the N-containing sublayers, the individual sublayer thickness is close to 4 nm, and the approximate composition Ti 0.33 Al 0.67 For the sublayers with N, the individual sublayer thickness was close to about 8 nm.

[0101] When L2 was deposited using -50 V (samples S2, S4, and S6), the deposition time for L2 was 42 min. Therefore, L2 consisted of approximately 130 sublayer periods and had the approximate composition Ti 0.50 Al 0.50 For the N-containing sublayers, the individual sublayer thickness is close to 4 nm, and the approximate composition Ti 0.33 Al 0.67 For the sublayers with N, the individual sublayer thickness was close to about 8 nm.

[0102] Hardness and Young's modulus of the first (Ti,Al)N multilayer: The hardness and Young's modulus of the (Ti,Al)N sublayer stacks L1 and L2 deposited in Example 1 were measured by depositing L1 and L2 separately, respectively, directly on the substrate and then performing measurements. The thickness of the sublayer stacks L1 and L2 was approximately 2 μm. The results are shown in Table 3. Alternatively, the hardness and Young's modulus of L1 and L2 could be measured on the cross-sectional area of ​​the first (Ti,Al)N multilayer, respectively, or on an angle-polished sample. TIFF0007728261000003.tif42170

[0103] Deposition of the first gamma-aluminum oxide layer: All samples S1 to S6 were provided with a first gamma-aluminum oxide layer on the first (Ti,Al)N layer.

[0104] The Hauzer HTC1000 PVD system is set up for deposition by bipolar pulsed magnetron sputtering.

[0105] For the deposition of aluminum oxide, two Al targets (800 mm x 200 mm x 10 mm each) were used, and a dual magnetron was applied. The bias power supply was used in bipolar pulse mode with 45 kHz and a 10 ms off time. The magnetron power supply was pulsed at 60 kHz (±2 kHz) and the pulse morphology was sinusoidal. The cathode voltage during the stabilized phase of processing was 390 V. The deposition was carried out using a substrate that was rotated three times. The required deposition parameters and measurement results (measured with the cutting tool to be coated, positioned in the center of the reactor height) are shown in Table 5. TIFF0007728261000004.tif67170

[0106] 0.6 μm of aluminum oxide was deposited on samples S1 to S6.

[0107] XRD measurements showed only gamma phase aluminum oxide peaks.

[0108] Hardness and Young's modulus of the first gamma-aluminum oxide layer: The hardness and Young's modulus of the first gamma-aluminum oxide layer were measured by separately depositing approximately 1 μm of gamma-aluminum oxide on the cemented carbide substrate using the same deposition conditions as used for samples S1-S6. Table 6 shows the results. Alternatively, the hardness and Young's modulus could be measured on the cross-sectional area of ​​the bevel-polished sample or first gamma-aluminum oxide layer. TIFF0007728261000005.tif27170

[0109] Deposition of a set of alternating second (Ti,Al)N multilayers and second gamma-aluminum oxide layers: Samples S1-S6 were further deposited with a set of alternating second (Ti,Al)N multilayers and second gamma-aluminum oxide layers.

[0110] Three second (Ti,Al)N multilayers and two second gamma-aluminum oxide layers are deposited, with a layer sequence of (Ti,Al)N-Al2O3-(Ti,Al)N-Al2O3-(Ti,Al)N.

[0111] The first two layers of the second (Ti,Al)N multilayer and the two second gamma-aluminum oxide layers each had a thickness of about 0.1 μm, and the third layer of the second (Ti,Al)N multilayer was slightly thicker, at about 0.3 μm.

[0112] The second (Ti,Al)N multilayer was deposited in the same manner as the first (Ti,Al)N multilayer sublayer stack L2 for each of samples S1-S6, i.e., using a circular arc PVD technique (CARC+) with a constant magnetic field configuration during deposition on a Hauzer HTC 1000 system. All other parameters and process conditions were the same as those used to fabricate the first (Ti,Al)N multilayer sublayer stack L2. The bias used to fabricate the second (Ti,Al)N multilayer was -40 V.

[0113] For the deposition of the second (Ti,Al)N multilayer, three targets were used: 1x "Ti50Al50" + 2x "Ti33Al67" as for the deposition of the first (Ti,Al)N multilayer L2. The processing parameters are summarized in Table 7. TIFF0007728261000006.tif45170

[0114] The deposition time for each second (Ti,Al)N multilayer was approximately 200 seconds. Since the process conditions for fabricating the second (Ti,Al)N multilayer were the same as for fabricating the sublayer stack L2 of the first (Ti,Al)N multilayer, it can be estimated that a deposition time of 200 seconds would give a layer thickness of the second (Ti,Al)N multilayer of 0.11 μm. Since the number of sublayer periods is approximately 10 for a 200-second deposition, the individual sublayer thicknesses are approximately 0.11 μm. 0.50 Al 0.50 The N-containing sublayer is close to 4 nm and has a similar composition to Ti 0.33 Al 0.67 For the sublayers with N, this is close to an individual sublayer thickness of about 8 nm.

[0115] The second gamma-aluminum oxide layer was deposited by bipolar pulsed magnetron sputtering using the same parameters and conditions as for depositing the first gamma-aluminum oxide layer.

[0116] Finally, an outer 0.2 μm ZrN layer was then deposited on the samples for color and / or wear detection purposes. ZrN deposition was performed by arc evaporation using an arc current of 150 A per target, a nitrogen pressure of 4 Pa, and a bias voltage of −40 V.

[0117] Therefore, the total thickness of the coating for samples S1, S3 and S5 was about 5.5 μm.

[0118] Therefore, the total thickness of the coating for samples S2, S4 and S6 was about 4.5 μm.

[0119] The resulting layer structure is shown in Table 8. TIFF0007728261000007.tif125170

[0120] Therefore, the total coating thickness of samples S1, S3 and S5 was about 5.5 μm, and the total coating thickness of samples S2, S4 and S6 was about 4.5 μm.

[0121] The level of residual stress was determined on the cemented carbide substrate of sample S1, where the entire coating was deposited but without any post-treatment. The result was -149 MPa (i.e., a residual compressive stress of 149 MPa). Values ​​of around -150 MPa are considered typical for all samples S1 to S6.

[0122] The level of residual stress was also determined for the first (Ti,Al)N multilayer, which was close to the substrate surface. Sample S1 was selected. The result was 154 MPa for the sample (i.e., a residual tensile stress of 154 MPa).

[0123] A further sample, S7, was prepared, with a coating deposited much thinner than either of samples S1-S6. For this sample, the bias voltages used during the deposition of the first (Ti,Al)N multilayer were -60 V for L1 and -50 V for L2. For the second (Ti,Al)N multilayer, -50 V was used (similar to L2). This sample had the same type of layers and layer sequence as present in the coatings of samples S1-S6 (see Table 8), but in most cases had a thinner deposited coating. The total coating thickness was 3.7 μm. Table 9 shows the layer thicknesses. The level of residual stress was similarly determined for the first (Ti,Al)N multilayer near the substrate surface of this sample. TIFF0007728261000008.tif125170

[0124] The level of residual stress was determined for the first (Ti,Al)N multilayer, closest to the substrate surface, and the result was −1198 MPa (i.e., a residual compressive stress of 1198 MPa) for the sample.

[0125] Post-processing Samples S1-S6 and S7 were post-treated by shot peening followed by wet blasting, which smooths the coating surface and imparts a level of average compressive stress to the coating.

[0126] Shot peening parameters: Blast pressure 5 bar Blast angle: 90° to the surface plane of the coating Blast distance 10cm Blasting material: ZrO2 beads (diameter 75~125μm), Blast duration: 2 seconds

[0127] The ZrO2 beads used had the following composition: ZrO2: 60~65% by weight SiO2: 25~30% by weight Al2O3: 2~5% by weight The rest is other oxides (CaO, Fe2O3, TiO2) Unblasted substrate - 80 MPa The residual stress in the substrate was -1120 MPa.

[0128] Wet blasting parameters: Blast pressure 1.6~2 bar Blast angle: 75° to the surface plane of the coating Blast distance 10cm Blasting material Al2O3F220(FEPA)

[0129] Blasting is performed using equipment with 14 blast guns, designed to blast trays of approximately 50 to 400 cutting tool inserts. With 40 to 50 seconds of blasting during rotation, the estimated blast time per insert is 1 to 3 seconds.

[0130] The level of residual stress was determined on the cemented carbide substrate of sample S1 after the entire coating was deposited and after both post-treatment shot peening and wet blasting. The result was -1133 MPa (i.e., a compressive stress of 1133 MPa).

[0131] The level of residual stress was also determined for the first (Ti,Al)N multilayer, which is closest to the substrate surface. Samples S1 and S7, in which the entire coating was deposited and subjected to both post-treatment shot peening and wet blasting, were tested. The results were -1258 MPa (i.e., 1258 MPa residual compressive stress) for sample S1 and -1225 MPa (i.e., 1225 MPa residual compressive stress) for sample S7. Thus, the same stress level was reached for both samples.

[0132] Table 10 summarizes the results from all residual stress measurements. TIFF0007728261000009.tif50170

[0133] The post-treatment process increases the residual compressive stress at the bottom of the coating (for thicker coatings) to a level of approximately 1 GPa, while the surface of the substrate has the same residual stress level after the post-treatment process.

[0134] Example 2: Preparation of a comparative sample Comparative coated cutting tool samples S8-S10, essentially according to the prior art U.S. Pat. No. 8,709,583, were prepared by depositing coatings onto cutting tool bodies, which were inserts having geometries ADMT160608R-F56 ​​(for sample S8), ODHT050408-F57 (for sample S9), and P2808.1 (for sample S10), respectively. For samples S8 and S9, the cutting tool bodies consisted of a cemented carbide with a composition of 88 wt. % WC, 1.5 wt. % (Ta,Nb)C, and a binder phase of 10.5 wt. % Co. The average WC grain size dWC was 0.8 μm. For sample S10, the cutting tool body consisted of a cemented carbide with a composition of 87.5 wt. % WC, 0.5 wt. % Cr, and a binder phase of 12.5 wt. % Co. The average WC grain size dWC was 0.4 μm.

[0135] The coating was deposited using a PVD coating machine, Hauzer HTC1000, to produce a seven-layer coating: 1. (Ti,Al)N (ratio Ti:Al = 33:67 at.%) with a thickness of 2 μm, deposited by arc evaporation; 2. Aluminum oxide with a layer thickness of 0.5 μm, deposited by reactive magnetron sputtering; 3. (Ti,Al)N (ratio Ti:Al = 33:67 at.%) with a layer thickness of 0.2 μm, deposited by arc evaporation; 4. Aluminum oxide with a layer thickness of 0.15 μm, deposited by reactive magnetron sputtering; 5. (Ti,Al)N (ratio Ti:Al = 33:67 at.%) with a layer thickness of 0.2 μm, deposited by arc evaporation. 6. Aluminum oxide with a layer thickness of 0.15 μm, deposited by reactive magnetron sputtering; 7. ZrN deposited by arc evaporation with a layer thickness of 0.6 μm.

[0136] Prior to the coating operation, the substrate was cleaned in alcohol and further cleaned using Ar ion bombardment prior to deposition of the layer in a vacuum chamber, however, the Ar ion bombardment only proceeded to remove approximately 0.2 μm of substrate material.

[0137] Layer deposition: 1st, 3rd and 5th layers: Deposition of (Ti,Al)N was performed by arc evaporation at 3 Pa nitrogen and a bias voltage in DC mode of −40 V and a temperature of about 550° C. with a vaporizer current of 65 A per source.

[0138] Second, fourth and sixth layers: Aluminum oxide deposition was performed by reactive magnetron sputtering at a specific cathode power of approximately 7 W / cm2 with 0.5 Pa Ar and oxygen as reactive gases (flow rate approximately 80 sscm), a bipolar pulsed bias voltage of -150 V (70 kHz), and a temperature of approximately 550 °C.

[0139] Layer 7: ZrN was deposited in an arc at 4 Pa ​​nitrogen and a bias voltage in DC mode of −40 V and a temperature of about 550° C. with a vaporizer current of 150 A per source.

[0140] Table 11 summarizes the layer sequence in comparative samples S8-S10. TIFF0007728261000010.tif60170

[0141] The comparative samples were also tested with a shot peening post treatment as was done on the inventive samples of Example 1. However, the coating spalled off.

[0142] Example 3 - Cutting test The performance of coated cutting tool samples S1-S6 according to the invention was tested in milling operations along with comparative samples S8-S10, see Table 12 which summarizes the samples. TIFF0007728261000011.tif67170

[0143] Samples S1 and S2 were compared against comparative sample S8.

[0144] Samples S3 and S4 were compared against comparative sample S9.

[0145] Samples S5 and S6 were compared against comparative sample S10.

[0146] Test 1: The metal cutting performance of coated cutting tool samples S1, S2 and S8 was tested in face milling operations using a face milling cutter type F2010.UB.127.Z08.02R681M (according to DIN 4000-88) manufactured by Walter AG, Tübingen, Germany on a Heller FH120-2 machine under the following conditions:

[0147] Cutting conditions: Blade feed amount f z [mm / blade]:0.2 cutting speed vc [m / min]:283 Axial depth of cut a p [mm]:98 Radial cutting depth a e [mm]:3 Workpiece material: 42CrMo4; Tensile strength Rm: 740N / mm 2

[0148] The cut-off criterion is the maximum wear on the tool flank, i.e., the deepest crater V observed on the tool flank. Bmax and reached 0.3 mm.

[0149] Table 13 shows the results of the cutting tests. TIFF0007728261000012.tif39170

[0150] Test 2: The metal cutting performance of coated cutting tool samples S3, S4 and S9 was tested in face milling operations using a face milling cutter type F4081.B.052.Z05.04 (according to DIN 4000-88) manufactured by Walter AG, Tübingen, Germany on a Heller FH120-2 machine under the following conditions:

[0151] Cutting conditions: Blade feed amount f z [mm / blade]:0.23 cutting speed v c [m / min]:240 Axial cutting depth a p [mm]:3 Radial cutting depth a e [mm]:40 Workpiece material: 1.4435 (X2CrNiMo18-14-3); Tensile strength Rm: 515N / mm 2

[0152] The cut-off criterion is the maximum wear on the tool flank, i.e., the deepest crater V observed on the tool flank. Bmax and reached 0.3 mm.

[0153] Table 14 shows the results of the cutting tests. TIFF0007728261000013.tif38170

[0154] Test 3: The metal cutting performance of coated cutting tool samples S5, S6 and S10 was tested in face milling operations using a face milling cutter type F2010.UB.127.Z08.02R681M (according to DIN 4000-88) manufactured by Walter AG, Tübingen, Germany on a Heller FH120-2 machine under the following conditions:

[0155] Cutting conditions: Blade feed amount f z [mm / blade]:0.2 cutting speed v c [m / min]:150 Axial cutting depth a p [mm]:3 Radial cutting depth a e [mm]:50 Workpiece material: 1.4301 (X5CrNi18-10)

[0156] The cut-off criterion is the maximum wear on the tool flank, i.e., the deepest crater V observed on the tool flank. Bmax and reached 0.3 mm.

[0157] Table 15 shows the results of the cutting tests. TIFF0007728261000014.tif38170

Claims

1. A coated cutting tool (1) comprising a substrate body (5) and a coating (6), wherein the substrate body (5) is a WC—Co-based cemented carbide body containing 5 to 15 wt % Co, and the coating (6) is formed from the substrate body (5) in the following order from the surface thereof: a first (Ti,Al)N multilayer (7) which is a multilayer of alternating (Ti,Al)N sublayers, the total atomic ratio of Ti:Al in said first (Ti,Al)N multilayer (7) is between 33:67 and 67:33; the total thickness of said first (Ti,Al)N multilayer is between 1 and 8 μm; - each of the individual (Ti,Al)N sublayers in said first (Ti,Al)N multilayer (7) has a thickness of 1 to 25 nm; each individual (Ti,Al)N sublayer within said first (Ti,Al)N multilayer (7) differs from its immediately adjacent (Ti,Al)N sublayer in terms of the atomic ratio Ti:Al; a first (Ti,Al)N multilayer (7) that is a multilayer of alternating (Ti,Al)N sublayers, the first (Ti,Al)N multilayer (7) comprising two or more (Ti,Al)N sublayer stacks arranged directly above one another, wherein at least two individual (Ti,Al)N sublayers are present within the same (Ti,Al)N sublayer stack, the at least two individual (Ti,Al)N sublayers having different Ti:Al atomic ratios, and the total Al content within each of the (Ti,Al)N sublayer stacks increases from one (Ti,Al)N sublayer stack to the next in a direction towards the outer surface of the coating (6); a first gamma-aluminum oxide layer (8) having a thickness of 0.3 to 1.5 μm; a set of alternating second (Ti,Al)N multilayers (9) and second gamma-aluminum oxide layers (10), - the number of each of said second (Ti,Al)N multilayers (9) and said second gamma-aluminum oxide layers (10) is greater than or equal to two; each of said second (Ti,Al)N multilayers (9) is a multilayer of alternating (Ti,Al)N sublayers, the total atomic ratio of Ti:Al in said second (Ti,Al)N multilayer (9) is in the range of 33:67 to 67:33; the thickness of each of said second (Ti,Al)N multilayers (9) is between 0.05 and 0.5 μm; - each of the individual (Ti,Al)N sublayers in said second (Ti,Al)N multilayer (9) has a thickness in the range of 1 to 25 nm; each individual (Ti,Al)N sublayer within said second (Ti,Al)N multilayer (9) differs from its immediately adjacent (Ti,Al)N sublayer in terms of the atomic ratio Ti:Al; a set of alternating second (Ti,Al)N multilayers (9) and second gamma-aluminum oxide layers (10), each of said second gamma-aluminum oxide layers (10) having a thickness of 0.05 to 0.5 μm; Including, A coated cutting tool, wherein the total thickness of the entire coating (6) of the coated cutting tool (1) is 3 to 15 μm.

2. The coated cutting tool (1) according to claim 1, wherein the surface zone of the substrate body (5) exhibits a residual compressive stress of at least 0.5 GPa.

3. 3. The coated cutting tool (1) according to claim 1, wherein the atomic ratio Ti:Al of the individual (Ti,Al)N sub-layer type of the first (Ti,Al)N multilayer (7), which has the highest Al content among the individual (Ti,Al)N sub-layer types, is in the range of 20:80 to 60:

40.

4. 4. The coated cutting tool (1) according to claim 1, wherein the atomic ratio Ti:Al of the individual (Ti,Al)N sub-layer type of the first (Ti,Al)N multilayer (7), which has the lowest Al content of the individual (Ti,Al)N sub-layer types, is in the range of 35:65 to 80:

20.

5. The coated cutting tool (1) according to any one of claims 1 to 4, wherein the thickness of each (Ti,Al)N sub-layer stack of the first (Ti,Al)N multilayer (7) is between 0.5 and 5 μm.

6. 6. The coated cutting tool (1) according to any one of claims 1 to 5, wherein the first (Ti,Al)N multilayer (7) consists of a stack of 2 to 5 (Ti,Al)N sublayers arranged directly on top of each other.

7. 7. The coated cutting tool (1) according to any one of claims 1 to 6, wherein the first (Ti,Al)N multilayer (7) has a Vickers hardness HV 0.0015 of 2800 or more and / or a reduced Young's modulus of more than 350 GPa.

8. 8. The coated cutting tool (1) according to claim 1, wherein a residual compressive stress of 0.5 to 2 GPa is present in a portion of the first (Ti,Al)N multilayer (7) that is at least 100 nm and at most 1 μm thick from a contact surface of the (Ti,Al)N multilayer that is arranged in a direction towards the substrate body (5).

9. The coated cutting tool (1) according to any one of claims 1 to 8, wherein the gamma-aluminum oxide layer (8) has a Vickers hardness HV0.0015 of 3000 to 3500 HV0.0015 and a reduced Young's modulus of 350 to 390 GPa.

10. 10. The coated cutting tool (1) according to any one of claims 1 to 9, wherein the coating comprises an outermost layer (11) which is a metal nitride layer, the metal of which belongs to group 4, 5 or 6 of the periodic table of the elements.

11. The coated cutting tool (1) according to any one of claims 1 to 10, which is a cutting insert for milling, turning, drilling, drill or end mill.

12. A method for the production of a coated cutting tool (1) consisting of a substrate body (5) and a deposited coating (6), comprising: - Providing a substrate body (5) which is a WC-Co based cemented carbide body containing 5 to 15 wt% Co; - subjecting the surface of said substrate body (5) to a pretreatment, which is an ion etching procedure, so that a thickness of at least 0.5 μm of said substrate body (5) is removed; depositing a 1-8 μm thick layer of a first (Ti,Al)N multilayer (7) by cathodic arc evaporation PVD using at least two TiAl targets with different Ti:Al atomic ratios in a chamber containing nitrogen gas at a pressure of −5 to 15 Pa, using a bias voltage of −20 to −80 V, and an applied arc current of 50 to 200 A, wherein the (Ti,Al)N multilayer (7) is a multilayer of alternating (Ti,Al)N sublayers, the atomic Ti:Al ratios of the TiAl targets being selected such that the total atomic ratio of Ti:Al is between 33:67 and 67:33, each of the individual (Ti,Al)N sublayers having a thickness in the range of 1 to 25 nm, and depositing a layer 1-8 μm thick, wherein each (Ti,Al)N sublayer differs from its immediately adjacent (Ti,Al)N sublayer in terms of atomic ratio Ti:Al, the (Ti,Al)N multilayer (7) being deposited to include two or more (Ti,Al)N sublayer stacks arranged directly above one another, at least two individual (Ti,Al)N sublayers being present within the same (Ti,Al)N sublayer stack, the at least two individual (Ti,Al)N sublayers having different Ti:Al atomic ratios, and the total Al content within each of the (Ti,Al)N sublayer stacks increasing from one (Ti,Al)N sublayer stack to the next in a direction toward an outer surface of the first (Ti,Al)N multilayer (7); -1 to 5 Pa total gas pressure, 0.001 to 0.1 Pa oxygen partial pressure, 400 to 600 °C temperature, 4 to 20 W / cm ２ depositing a first gamma-aluminum oxide layer (8) having a thickness of 0.3 to 1.5 μm by reactive magnetron sputtering PVD using at least one Al target in an oxygen-containing gas volume using a magnetron power density of 1000 W, a bias voltage of 80 to 200 V, and a pulsed bias current of 20 to 60 A; - depositing a set of alternating layers of second (Ti,Al)N multilayers (9) and second gamma-aluminum oxide layers (10), wherein said second (Ti,Al)N multilayers (9) and said second gamma-aluminum oxide layers (10) are deposited using the same process conditions as those used to deposit said first (Ti,Al)N multilayers (7) and said first gamma-aluminum oxide layers (8), respectively, wherein the number of said second (Ti,Al)N multilayers (9) and said second gamma-aluminum oxide layers (10) is two or more, each of said second (Ti,Al)N multilayers (9) is a multilayer of alternating (Ti,Al)N sublayers, and wherein said second (Ti,Al)N multilayers (9) are ... depositing a set of alternating second (Ti,Al)N multilayers (9) and second gamma-aluminum oxide layers (10), wherein the total atomic ratio of Ti:Al in the layers (9) is between 33:67 and 67:33, the thickness of the second (Ti,Al)N multilayer (9) is between 0.05 and 0.5 μm, each individual (Ti,Al)N sublayer in the second (Ti,Al)N multilayer (9) has a thickness between 1 and 25 nm, each individual (Ti,Al)N sublayer in the second (Ti,Al)N multilayer (9) differs from its immediately adjacent (Ti,Al)N sublayer in terms of its atomic ratio of Ti:Al, and the thickness of the second gamma-aluminum oxide layer (10) is between 0.05 and 0.5 μm; wherein the total thickness of the entire deposited coating (6) of the coated cutting tool (1) is between 3 and 15 μm; - subjecting the deposited coating (6) to a first post-treatment procedure comprising shot peening using zirconium oxide based ceramic beads, so that a compressive stress of at least 0.5 GPa is induced in the surface zone of the substrate body (5); - subjecting the deposited coating (6) to a second post-treatment procedure by wet blasting with a slurry of aluminium oxide particles; A method comprising:

13. 13. The method of claim 12, wherein after deposition of the set of alternating layers of the second (Ti,Al)N multilayer (9) and the second gamma-aluminum oxide layer (10), there is an outermost layer (11) deposited before the first post-treatment procedure, the outermost layer (11) being a metal nitride layer, the metal of the metal nitride layer belonging to group 4, 5 or 6 of the periodic table of the elements.

14. 14. The method according to any one of claims 12 to 13, wherein beads used in the shot peening are within a size range of 70 to 125 μm, the shot peening is carried out using a blasting pressure of 3 to 6 bar, the shot peening operation time is 2 to 10 seconds, the distance between a nozzle used in the shot peening and wet blasting and the surface of the coated cutting tool (1) is 75 to 150 mm, and the shot peening is carried out with a shot direction substantially perpendicular to the surface of the coated cutting tool (1).

15. 15. The method according to any one of claims 12 to 14, wherein the second post-treatment procedure comprises wet blasting using a blasting pressure of 1.5 to 2 bar, the concentration of aluminum oxide particles in the slurry is 15 to 20% by volume, the aluminum oxide particles used in the wet blasting belong to one or more of FEPA designations F240, F280 and F320, the blasting time in the wet blasting is 2 to 60 seconds, the distance between the wet blasting gun nozzle and the surface of the coated cutting tool (1) is 50 to 200 mm, and the wet blasting is carried out with a blasting direction at an angle of 60 to 90 degrees relative to the surface of the coated cutting tool (1).

16. 16. The method according to any one of claims 12 to 15, wherein the wet blasting is carried out until a residual compressive stress of at least 0.2 GPa is induced in the coating (6) when averaged over the thickness of the coating.

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