Cutting tools with TiAlN coatings

Abstract

The metal cutting insert has a substrate of carbide, cermet or ceramic, and at least one cutting edge defined between a rake face and a flank face. The cutting insert has a CVD coating, and the CVD coating includes a layer of aluminum titanium nitride, has a face-centered cubic lattice structure, and is represented by the formula (Al x Ti 1-x M y )C z N 1-z , where the stoichiometric coefficient of aluminum is 0.30 < x < 0.95, M is at least one element selected from the group consisting of Cl and Ar, the stoichiometric coefficient of M is 0 < y < 0.01, and the stoichiometric coefficient of carbon is 0 ≦ z ≦ 0.3. (Al x Ti 1-x M y )C z N 1-z layer satisfies the relationship 10 < |S1 - S2| < 500 MPa, where S1 is the residual stress measured on the rake face and S2 is the residual stress measured on the flank face.

Description

[Technical Field]

[0001] The present invention relates to a metal-cutting insert coated with at least one layer comprising aluminum, titanium, and nitrogen applied by chemical vapor deposition, and a method for making the same, the layer having differential residual stresses of up to 500 MPa on the rake face and flank face. The present invention also relates to a metal-cutting system comprising an insert holder and at least one such metal-cutting insert. [Background technology]

[0002] Metal cutting tools, particularly cutting inserts, have a hard substrate of cemented carbide, cermet, ceramic, or steel and are typically coated with a hard material coating to improve wear or cutting properties. Known coatings for metal cutting tools include layers of carbides, nitrides, oxides, carbonitrides, oxynitrides, oxycarbides, oxycarbonitrides, borides, boronitrides, borocarbides, boroncarbonitrides, boronoxynitrides, boronoxycarbides, or boronoxycarbonitrides of elements from groups IVa to VIIa of the Periodic Table, and / or aluminum, mixed metal phases, and phase mixtures of the aforementioned compounds. Examples of the aforementioned compounds are Al2O3 and titanium-based coatings such as TiN, TiC, TiCN, and TiAlN. These coatings are applied by CVD (chemical vapor deposition), MT-CVD (medium-temperature chemical vapor deposition), PCVD (plasma-assisted CVD), or PVD (physical vapor deposition) methods. Coating layers containing titanium and nitrogen generally have lower oxidation temperatures than coatings containing titanium, nitrogen, and aluminum because the latter group of coating layers forms a thin surface layer of aluminum oxide during high-temperature dry machining applications. Higher aluminum content further increases hardness.

[0003] Methods for depositing cubic titanium aluminum nitride coatings (TiAlN) by CVD are well known and are described, for example, in Czettl, Christoph & Schleinkofer, U & Schedle, F & Wolf, C & Lechleitner, M & Holzschuh, Helga & Burgin, W. (2017), CVD TiAlN - Development and challenges for use in mass production, History and development of CVD-TiAlN, 19th Plansee Seminar, June 2017. One advantage of CVD-deposited face-centered cubic TiAlN over PVD-deposited TiAlN is that the CVD-deposited TiAlN layer has a thickness that exceeds that of the PVD-deposited TiAlN layer, which may increase tool life. Another advantage is that the aluminum content of cubic CVD TiAlN is higher than that of cubic PVD TiAlN layers, i.e., greater than 60% or greater than 70% of the metal content of the coating, which may impart superior oxidation resistance to the high-aluminum CVD TiAlN layer. Some CVD TiAlN coatings may have a preferential orientation or configuration.

[0004] Residual stresses can form after coating at elevated temperatures, for example, between the coating and the substrate, and / or between individual layers of the coating, as a result of different thermal expansion coefficients of the materials in the coating and the substrate. While some CVD processes typically result in coatings with compressive residual stresses, CVD coatings exhibit tensile residual stresses after deposition. Residual stresses are known to affect the wear resistance of metal-cutting inserts and the adhesion of coatings to the substrate of the metal-cutting insert.

[0005] Residual stress is usually expressed as sin 2Residual stress is measured using non-destructive phase-selective X-ray diffraction methods such as the Ψ method, the universal plot method, or the single-axis tilt method. Those skilled in the art know that repeated residual stress measurements at the same location on a sample will not yield identical readings, but will be within a standard deviation, and within this range, the samples are considered to have the same residual stress (see, for example, He, Baoping Bob, and Kingsley L. Smith, "Strain and Stress Measurements with a Two-Dimensional Detector," (1999)). The geometry of cutting inserts can sometimes complicate residual stress measurements, but there are known methods to overcome this problem.

[0006] Post-coating mechanical surface treatments that adjust residual stresses in cutting tool coatings are typically advantageous because they prevent or close surface cracks, improve the fatigue properties of the coating, and extend the life of the cutting insert. These post-coating treatments, including, for example, blasting, shot peening, or brushing of cutting inserts coated with CVD, PCVD, or PVD layers, are known to reduce tensile residual stresses or increase compressive residual stresses in the outer layer(s) of the coating, the entire coating, or even the substrate. However, compressive stresses above a certain point can lead to adhesion problems and spontaneous fragmentation, chipping, or separation of the surface coating.

[0007] Post-coating treatments are also used to modify the surface roughness on the rake face and / or flank face and / or on the cutting area, or to at least partially remove the top layer, and / or to increase the hardness of the coating. Residual stresses are usually specified in megapascals (MPa), with tensile residual stresses having a positive sign "+" while compressive residual stresses have a negative sign "-".

[0008] Various, somewhat contradictory, published examples of desirable residual stress ranges for CVD TiAlN layers in cutting insert coatings include, by way of example, residual stresses between 300 and -5000 MPa within 500 μm from the cutting edge, or alternatively between -0.4 and -0.3 GPa, or between -0.5 GPa and -5 GPa, including formulas giving the difference between maximum and minimum residual stress values on any one of the rake face, flank face or cutting edge, such as 0.5 GPa to 3 GPa, or, more perplexingly, 3 GPa to 5 GPa, as in WO2020 / 079952.

[0009] A common cause of failure of cutting tools coated with the above-mentioned coatings in applications such as milling or turning is chipping on the rake face and / or cutting edge. Summary of the Invention [Means for solving the problem]

[0010] It is therefore an object of the present invention to provide a metal cutting insert for machining refractory metals, hard metals, and iron-based materials, particularly cast iron and stainless steel. The metal cutting insert according to one aspect of the present invention is coated with a coating comprising at least one layer of aluminum titanium nitride deposited by chemical vapor deposition (CVD), the coated cutting insert having improved toughness over the state of the art, improved chipping resistance, longer tool life, and an upper limit on the difference in rake and flank residual stresses after rake and / or flank blasting. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram of a 2D detector configuration for a single-axis tilt method. [Figure 2a] 1 is a graph of the tool life of samples A2i and A2ii on two different workpieces, the graph being normalized to the tool life of comparative prior art samples B2i and B2ii. [Figure 2b] 1 is a graph of the tool life of comparative samples B2i and B2ii. [Figure 3a]10 is a photograph of the rake face and cutting edge of sample A2i after milling a GGG50 workpiece for 28 minutes. [Figure 3b] 10 is a photograph of the rake face and cutting edge of sample A2ii after milling a GGG50 workpiece for 32 minutes. [Figure 3c] 10 is a photograph of the rake face and cutting edge of sample B2i after milling a GGG50 workpiece for 28 minutes. [Figure 3d] 10 is a photograph of the rake face and cutting edge of sample B2ii after milling a GGG50 workpiece for 28 minutes. [Figure 4a] 10 is a photograph of the rake face and cutting edge of sample A2iii after milling an SAE4340 workpiece for 1.7 minutes. [Figure 4b] 10 is a photograph of the rake face and cutting edge of sample A2iv after milling an SAE4340 workpiece for 4.8 minutes. [Figure 4c] 10 is a photograph of the rake face and cutting edge of comparative sample B2iii after milling an SAE4340 workpiece for 1.7 minutes. [Figure 4d] 10 is a photograph of the rake face and cutting edge of comparative sample B2iv after milling an SAE4340 workpiece for 4.8 minutes. [Figure 5a] Single XRD 2D frame for residual stress evaluation. [Figure 5b] This frame is incorporated into a 1D spectrum. [Figure 6a] Unpolished surface of the insert, viewed with a 100x magnification lens on an NHT3 nanoindentation tester from Anton Paar GmbH. [Figure 6b] Polished surface of the insert with 100x magnification lens of an NHT3 nanoindentation tester from Anton Paar GmbH, where the X indicates the appropriate location for nanoindentation measurements. [Figure 7] FIG. 10 is a diagram of the working corner of the insert. [Figure 8a] 1 is an SEM micrograph of a vapor-deposited (AlxTi1-xMy)CzN1-z surface according to the present invention, showing well-defined cubic grains. [Figure 8b] SEM micrograph at the same magnification as that of FIG. 8a of the surface of (AlxTi1-xMy)CzN1-z according to the present invention after coating treatment, showing a "smeared" surface.

Mode for Carrying Out the Invention

[0012] The object is achieved by a metal cutting insert (hereinafter referred to as "cutting insert") made from a substrate of cemented carbide, cermet or ceramic. The substrate comprises at least one rake face and at least one flank face that intersect to form a cutting edge having at least one working corner as shown in FIG. 7, and a coating formed on the substrate by chemical vapor deposition. The coating has one or more layers, and at least one layer has a composition containing aluminum, titanium and nitrogen, has a face-centered cubic lattice structure, and is represented by the formula (Al x Ti 1-x M y )C z N 1-z where the stoichiometric coefficient of aluminum is 0.3 < x < 0.95, preferably 0.5 < x < 0.95, more preferably 0.67 < x < 0.95, and advantageously 0.8 < x < 0.90; M is at least one element selected from the group consisting of Cl and Ar; the stoichiometric coefficient of M is 0 ≦ y < 0.01, preferably 0 ≦ y < 0.005; the stoichiometric coefficient of carbon is 0 ≦ z < 0.3; and the (Al x Ti 1-x M y )C z N 1-z layer satisfies the relationship 10 < |S1 - S2| < 500 MPa, preferably 10 < |S1 - S2| < 400 MPa, and most preferably 10 < |S1 - S2| < 350 MPa, where S1 is the residual stress measured on the rake face and S2 is the residual stress measured on the flank face.

[0013] It has surprisingly been found that cutting inserts according to the invention having a coating within these parameters have improved wear resistance, particularly against chipping, over known cutting inserts and therefore have a longer tool life (e.g., when mounted on an insert holder and used in a metal cutting process), particularly in milling steel or cast iron materials and turning steel-based workpieces. The tool life of known cutting inserts can be shortened by wear on the flank of the insert due to thermal fatigue, particularly during milling operations, due to thermal cyclic loading, or can result in wear and / or chipping at the cutting edge and thermal cracks along the cutting edge that can reach completely through the coating and eventually pull out carbide compartments and eventually result in chipping.

[0014] In particular, the CVD (Al) content for each of the specified ranges described below is x Ti 1-x M y )C z N 1-z , preferably high aluminum (Al x Ti 1-x M y )C z N 1-z The combination of adjusting the layer residual stresses, S1 and S2 on the rake and flank faces, respectively, of the working corner and adjusting the residual stress difference |S1-S2| to be less than 500 MPa provides the cutting insert with increased chipping resistance, improved wear resistance, and significantly longer tool life.

[0015] The residual stress S1 is preferably within the range |S1|<3100 MPa. In some embodiments, the residual stress S1 is within the range |S1|<2800 MPa, and in other embodiments, -2200≦S1<2400 MPa.

[0016] Tool life is reduced when S1 has a residual stress exceeding 3100 MPa. The inventors have found that the wear resistance of cutting tools is improved within the entire range of S1 mentioned above. Compressive stress leads to increased tool life, but too high a compressive stress can lead to spalling.

[0017] The residual stress S2 is preferably within the range |S2|<2800 MPa. In some embodiments, the residual stress S2 is within the range |S2|<2500 MPa, and in other embodiments, -1700≦S2<1900 MPa. The inventors have discovered that within the specified S2 range, the wear resistance of cutting tools is improved by reducing chipping and improving toughness.

[0018] (Al x Ti 1-x M y )C z N 1-z The layer may have a thickness of 2 to 15 μm, preferably 3 to 15 μm, most preferably 4 to 10 μm. The coating may have a thickness of 2 to 25 μm, preferably between 3 and 20, most preferably 4 to 15 μm.

[0019] Tensile stresses typically arise in CVD coatings due to differences in the thermal expansion coefficients of the substrate and the coating layer. Generally, reducing tensile residual stresses or introducing compressive residual stresses in coatings, typically on the rake face and / or cutting edge, is desirable because it prevents or closes surface cracks, thereby improving the fatigue properties of the coating and, therefore, the tool. Adjusting the residual stresses can be achieved by post-coating treatments such as brushing, blasting, and shot peening.

[0020] The surface integrity of the outermost layer is altered by post-coating treatments, which induce plastic deformation in the surface layer, i.e., change the surface characteristics. This deformation is discernible under a microscope as shown by the difference between Figure 8a and Figure 8b. Figure 8a shows the surface of a vapor-deposited (Al x Ti 1-x M y )C z N 1-z8b shows the surface of a sprayed "blurred" surface feature according to some embodiments of the present invention, where at least some of the top vertices of the multifaceted grains have been deformed over a large portion of the micrograph area, and the sprayed outermost (Al x Ti 1-x M y )C z N 1-z The term outermost is synonymous with top and is relative to the substrate, i.e., furthest from the substrate.

[0021] In some embodiments, at least one rake face or flank face has undergone a post-coating treatment that results in surface features that appear as blurred in at least 90% of the micrograph area. Other embodiments have at least one rake face or flank face that appears as blurred in at least 70% of the micrograph, or that appear as blurred in at least 50% of the micrograph. Or in some embodiments, after a fairly light post-coating treatment, at least one rake face or flank face has undergone a post-coating treatment that results in surface features that appear as blurred in at least 20% of the micrograph area.

[0022] Post-coating treatment is often continued until a residual compressive stress is achieved, which generally provides better adhesive wear resistance, especially at elevated temperatures, but too high a compressive stress can result in delamination, adhesion problems, and chipping due to coating cohesion and / or adhesion.

[0023] Without being bound by any theory, it is believed that adjusting the difference in residual stress between the rake face and flank face is effective in reducing the residual stress at the cutting edge where these two faces are adjacent to each other during use of the cutting insert after post-coating treatment to improve fatigue properties. x Ti 1-x M y )C z N 1-zThe aluminum titanium nitride coating is believed to reduce the distortion of the layer on the flank and / or rake faces. x Ti 1-x M y )C z N 1-z It has been found that the (Al) layer exhibits a specific behavior in that it should be treated so that the strain induced in the layer is within the range specified in claim 1. Otherwise, non-homogeneous mechanical properties at the cutting edge will have a negative effect on tool life. Preferably, the (Al) layer on the rake face and / or flank face x Ti 1-x M y )C z N 1-z The residual stresses in the layer are such that the tensile residual stresses are reduced, or alternatively, the compressive residual stresses are reduced (Al x Ti 1-x M y )C z N 1-z The layer is processed within the specific ranges of S1 and S2 described above so that the Al x Ti 1-x M y )C z N 1-z The Vickers hardness of the layer is within the range defined in claim 10.

[0024] The substrate of the cutting insert may have a shape commonly used in cutting inserts, for example, the top view of the cutting insert may be a square, rhomboid, triangle, circle, oval, etc. Preferably, the cutting insert should be a milling cutting insert. The substrate includes at least one rake face and at least one flank face. The relief face, also known as a "flank face," and the rake face are connected to each other by an edge line. Expressions such as "flank face," "rake face," and "cutting edge" include within their meaning the surface of the substrate and any coating layer on the substrate.

[0025] (Al x Ti 1-x M y )C z N 1-zThe layer may have a hexagonal phase up to 15% by volume. It has a hexagonal lattice (Al x Ti 1-x M y )C z N 1-z If the ratio of the hexagonal phase is too high, the wear resistance is reduced and the tool life is shortened. A higher ratio of (Al x Ti 1-x M y )C z N 1-z in the fcc phase is advantageous for improving wear resistance. A preferred embodiment has a hexagonal phase up to 5 vol%, most preferably about 100 vol% of the fcc phase.

[0026] (Al x Ti 1-x M y )C z N 1-z The layer may include one or more features of known cubic titanium aluminum nitride or titanium aluminum carbonitride rich in aluminum deposited by a CVD method known in the art, for example, a columnar crystal structure having an aspect ratio of about 2.5 to 7, a thin layer structure having periodic alternating regions with different stoichiometric ratios of Ti and Al, the overall stoichiometric ratio of the layer is 0.5 < x < 0.95, and / or the precipitates at the grain boundaries have a higher Al content than in the grains.

[0027] The CVD coating of the present invention can be manufactured by known methods in an industrial-scale thermal CVD reactor described in JP-A-2001-341008. Alternatively, the CVD coating can be manufactured by the method described by S. Anderbouhr et al., Proceedings of the 14th International Conference, 1997. Another known thermal CVD method for depositing a Ti 1-X Al X N layer on a cemented carbide substrate that can be used is described in EP1902155. Another known thermal CVD method for depositing a Ti 1-X Al X N layer on a cemented carbide substrate in a high-temperature wall low-pressure CVD apparatus is described in "Aluminium-rich Ti 1-X Al XN Coatings by CVD-EuroPM2006-Hard Materials Thin and Thick Coatings".

[0028] Some further examples of known CVD methods for producing aluminum-rich cubic titanium aluminum nitride or carbonitride layers are disclosed in US6040012, Surface & Coatings Technology 205 (2010), pp. 1307-1312, WO2020 / 079952, US9976213, EP3441167, and US2018 / 0216224.

[0029] The trace elements chlorine and / or argon that may be present in the coating come from the gases used in the CVD process, e.g., Ar, TiCl4, and AlCl3 as optional carrier gases. These trace elements may be present in the layer in amounts up to 1 atomic percent, but above 1 at% are detrimental and reduce the hardness of the layer. In some embodiments, (Al x Ti 1-x M y )C z N 1-z The layer has no trace elements, i.e., y=0, and the layer has improved mechanical properties. In some embodiments, z=0, i.e., the layer has no trace elements, i.e., y=0, and the layer has improved mechanical properties. x Ti 1-x M y )N or (Al x Ti 1-x )N.

[0030] The substrate of the cutting insert can be any substrate known for cutting inserts. In a preferred embodiment, the substrate is made of a hard metal, also known as a cemented carbide, made from tungsten carbide and cobalt, and optionally a carbide, nitride, or carbonitride of an element from Groups IVa to VIIa of the periodic table. In some embodiments, the cemented carbide substrate can have a β-free zone to improve the toughness of the substrate, particularly for machining steel, while other embodiments, such as for machining cast iron, do not have a β-free zone. In other embodiments, the substrate can be a cermet, high-speed steel, ceramic, cubic boron nitride sintered substrate, or silicon nitride sintered substrate. For example, the substrate of the cutting insert can be a cemented carbide having a composition, by weight, of 90.5% WC, 0.5% CrC, and 9% Co, and sintered into a cutting tool shape.

[0031] In some embodiments, the rake face may be a flat surface, while some embodiments may have additional features such as, for example, a chip breaker. Likewise, this is also true for the flank face, which may be chamfered to form a non-flat surface.

[0032] In some embodiments, the coating comprises a single layer of (Al x Ti 1-x M y )C z N 1-z In other embodiments, the coating may have one or more additional layers. The one or more additional layers include layers of carbides, nitrides, oxides, carbonitrides, oxynitrides, oxycarbides, oxycarbonitrides, borides, boronitrides, borocarbides, boroncarbonitrides, boronoxynitrides, boronoxycarbides, or boronoxycarbonitrides of elements from Groups IVa-VIIa of the Periodic Table, and / or aluminum, mixed metal phases, and phase mixtures of the aforementioned compounds. A preferred additional layer comprises a carbide, nitride, or carbonitride of titanium. In some embodiments, the coating does not comprise a layer of alumina.

[0033] In a preferred embodiment, the coating is a substrate and (Al x Ti 1-x M y )C zN 1-z In another embodiment, the underlayer comprises a TiN layer and a TiCN layer, and the substrate is a cemented carbide.

[0034] In some embodiments, (Al x Ti 1-x M y )C z N 1-z The layer is the outermost layer of the coating. In these embodiments, the (Al x Ti 1-x M y )C z N 1-z At least some of the top vertices of the faceted grains of the layer are deformed and appear as blurring, and in other embodiments, the coating further comprises a TiN outermost layer. The outermost TiN layer has the advantage of providing signs of wear and / or easily detectable grade markings. In some embodiments, the outermost layer of the coating comprises a layer selected from the group of TiCN, ZrN, and ZrCN, or a multilayer made from layers selected from the group consisting of TiN, TiCN, ZrN, and ZrCN. (Al x Ti 1-x M y )C z N 1-z In embodiments having an outermost layer on a layer, the outermost layer has a surface with "smeared" surface features and exhibits plastic deformation on at least one of the rake face or flank face of the metal cutting insert.

[0035] In a preferred embodiment, (Al x Ti 1-x M y )C z N 1-zThe Vickers hardness of the layer satisfies the relationship |HV1 - HV2| < 500, preferably |HV1 - HV2| < 300, and most preferably 0 < |HV1 - HV2| < 100, where HV1 is the Vickers hardness measured on the rake face and HV2 is the Vickers hardness measured on the flank face. The Vickers hardness measured on the rake face can be within the range of 2300 < HV1 < 4200, preferably 2600 ≦ HV1 < 3800, more preferably 2900 ≦ HV1 < 3400, and the Vickers hardness measured on the flank face can be within the range of 2400 ≦ HV2 < 4000, preferably 2700 ≦ HV2 < 3600, more preferably 3000 ≦ HV2 < 3500. For each of the defined ranges according to this embodiment, the CVD(Al x Ti 1-x M y )C z N 1-z layer, preferably the high-aluminum CVD(Al x Ti 1-x M y )C z N 1-z layer, the adjustment of the residual stress, S1 and S2 on the rake face and the flank face respectively, the adjustment of the difference in residual stress |S1 - S2|, and the combination with the adjustment of the Vickers hardness range of HV1 and the Vickers hardness range of HV2, as well as the Vickers hardness range of |HV1 - HV2|, result in increased chipping resistance, improved wear resistance, and significantly longer tool life for the cutting insert, particularly in the milling and turning of steel-based workpieces compared to known cutting inserts. The tool life of known cutting inserts is shortened by wear on the flank face of the insert due to thermal fatigue caused by repeated thermal loads, especially during milling, or results in wear and / or chipping at the cutting edge, which may cause thermal cracks along the cutting edge. These thermal cracks can reach through the coating and ultimately pull out the carbide section, resulting in chipping.

[0036] The furnace can be any CVD furnace such as, for example, a BBX model or a Bernex reactor of the 750L 750S 530L 530S 325L 325S models. In some embodiments, the chemical vapor deposition method is enhanced by plasma activation.

[0037] In another aspect of the present invention, after depositing a CVD coating having at least one layer of (Al x Ti 1-x M y )C z N 1-z on a substrate, there is a method of treating a coated cutting insert according to the present invention, having stoichiometric coefficients of 0.30 < x < 0.95, preferably 0.50 < x < 0.95, more preferably 0.67 ≤ x < 0.95, advantageously 0.80 < x < 0.90, 0 ≤ y < 0.01, 0 ≤ z < 0.3, where M is at least one element selected from the group consisting of Cl and Ar. The rake face and / or flank face are subjected to post - coating mechanical treatment(s) such as spraying or brushing, etc., to correct the residual stress on the rake face and / or flank face. The term "spraying" includes wet spraying, dry spraying, jet spraying, shot peening. Due to the influence of the post - coating treatment, the integrity of the surface is changed by the plastic deformation of the surface layer described above. The plastic deformation is carried out by the generation and movement of dislocations that change the mechanical properties of the (Al x Ti 1-x M y )C z N 1-z layer, such as microhardness and residual stress. The "blurred" appearance of the outermost layer indicates that this surface has undergone post - coating treatment.

[0038] Those skilled in the art will know, for example, (Al x Ti 1-x M y )C z N 1-zThose skilled in the art will be familiar with known methods for modifying the residual stresses of such coatings with at least one layer of alumina. WO2020079952 describes a blasting method preferably carried out along the cutting edge area with alumina particles at an angle of 45°, a distance of 50 mm, for 10 seconds, while the cutting tool is rotated (e.g., at 60 rpm) so that a line passing through the center of the rake face and perpendicular to the rake face acts as the axis. Another example is EP3441167, which describes a method for modifying the residual stresses of such coatings with alumina spheres. x Ti 1-x describes a wet spraying method for coatings comprising a nitride or carbonitride layer of alumina spheres having an average particle size of 50 mm, a density of 10% by volume, a firing pressure of 0.2 MPa from a firing distance of 10 mm, and a firing time of 10 seconds. Another example of a known spraying method is described in US 9976213, which may be a dry or wet spraying process at a spraying agent pressure of 1 to 10 bar for a time of 10 to 600 seconds, preferably at a spray angle of 90°, the spraying pressure having a much greater effect on the evolution of residual stresses in the coating than the spraying duration.

[0039] A broad, all-around spraying method is not possible, given that the resulting residual stresses depend not only on the spraying parameters but also on the structure and thickness of the entire coating. Nevertheless, those skilled in the art can perform a few simple experiments, assuming known post-coating treatments, to determine the spraying parameters for the rake face and / or flank face, taking into account the structure and thickness of the entire coating, along with the structure and composition of the substrate and spraying medium selected for the method, so that the difference between the residual stresses on the rake face and the flank face is 500 MPa or less. Parameters can include spray pressure, spray duration, spray angle, nozzle diameter, the distance between the nozzle and the rake face and flank face of the insert being sprayed, and the nozzle movement over the sprayed surface. It is well within the knowledge of those skilled in the art to determine these parameters with working knowledge of their respective standard deviations, which usually result in a cumulative standard deviation of residual stresses even for identical spraying conditions.

[0040] The spray duration is in the range of 2 to 600 seconds, but can also be limited to the range of 5 to 60 seconds. The spray angle is the angle between the spray stream from the nozzle to the spray surface and the respective spray surface and can be between 0° and 90°. The pressure of a suitable spraying agent is in the range of 0.5 to 10 bar, preferably 1 to 4.5 bar.

[0041] The spraying agent or medium may be, for example, metal, glass, or ceramic particles, optionally round particles, steel, SiC, Al2O3, glass, or ZrO2. The specific stress conditions according to the invention can be established with either the spraying agents mentioned or other suitable spraying agents. With knowledge of the present invention, a person skilled in the art can select the desired medium from the method, technical equipment, or tribological point of view and arrive at the appropriate spraying parameters by simple testing. The average particle size of the spraying agent is preferably in the range of 90 to 400 mesh, preferably 180 to 320 mesh. The spraying medium is propelled against the surface by compressed air in the dry spraying method or by pressurized fluid in the wet spraying method.

[0042] The blowing angle, i.e. the angle between the treatment beam and the tool face, has a significant effect on the reduction or introduction of tensile residual stresses: the maximum change in residual stress occurs at a blowing angle of 90°.

[0043] For example, it is possible to achieve the residual stress difference between the rake face and flank face described in claim 1 by blasting both the rake face and flank face at a 45° angle using the same medium for slightly different amounts of time and / or at slightly different pressures. An alternative blasting method could be blasting both faces for the same amount of time and / or at the same pressure, but at different blasting angles to the rake face / flank face, e.g., 60° / 30° or 90° / 45°, etc. An alternative blasting method could be blasting only one of the faces for a shorter blasting time and / or at a slight blasting pressure, as long as the residual stress difference is less than 500 MPa. However, the present invention is not limited to these and the blasting processes described below.

[0044] After spraying, (Al x Ti1-x M y )C z N 1-z The layer satisfies the relationship 10<|S1-S2|<500 MPa, preferably 10<|S1-S2|<400 MPa, and most preferably 10<|S1-S2|<350 MPa, where S1 is the residual stress measured on the rake face and S2 is the residual stress measured on the flank face. The residual stress S1 may advantageously be in the range |S1|<3100 MPa, preferably |S1|<2800 MPa, and more preferably -2200≦S1<2400 MPa. The residual stress S2 may advantageously be in the range |S2|<2800 MPa, preferably |S2|<2500 MPa, and most preferably -1700≦S2<1900 MPa.

[0045] Residual stress is usually measured by non-destructive phase-selective X-ray diffraction methods. One commonly used method is sin 2 Ψ method. Cubic (Al x Ti 1-x M y )C z N 1-z When measuring residual stress in thin films, the relatively low angle at which the measured (200) reflection occurs can present difficulties in using this method in light of the fact that high 2θ peaks may not be available or appropriate for thin films and coatings.

[0046] The residual stress measurement method used by the inventors is a single-axis tilt method using a two-dimensional detector (see US Pat. No. 10,416,102 and Materials Research Proceedings Vol. 6 (2018) pp. 3-8). The method involves performing X-ray diffraction stress analysis on a sample, such as a thin film or coating. The sample has a surface with two orthogonal axes S1 and S2 within the plane of the surface and a third axis S3 perpendicular to the sample surface plane. An X-ray beam is directed at the sample surface at a relatively low angle relative to the surface plane. X-ray energy is diffracted from the sample and detected by the two-dimensional X-ray detector at multiple rotational orientations of the sample around S3. The third axis S3 is maintained at a constant tilt angle throughout the entire X-ray diffraction stress analysis, thereby avoiding significant errors associated with the movement of the stage orbit of the goniometer used in X-ray diffraction stress analysis. Measurements on a goniometer at low 2θ angles are quite sensitive.

[0047] The stress measured is x Ti 1-x M y )C z N 1-z The (200) plane of the S1 and S2 stress measurements are taken near the same working corner indicated by the circle, as shown in Figure 7. The diffraction vector coverage from the low 2θ angle diffraction ring is suitable for stress tensor measurements at a single tilt angle. Before proceeding with the stress measurements, a calibration of the setup (see Figure 1) was performed. The Ψ tilt for measuring stress is selected to be 40°.

[0048] The area detector is a BRUKER VANTEC-500 with a diameter of 140 mm. This detector is mounted at a distance of 200 mm from the center of the goniometer; that is, the center of the detector is 200 mm away from the center of the goniometer. The possible area for locating the center of the goniometer is indicated by the arrow in Figure 7. A Ni filter is used on the primary side, and a polycapillary condenser lens and a 1 mm nozzle are used for point focusing. For a satisfactory measurement with such a setup, the observed intensity of the maximum 2θ value of the (200) reflection should be at least 0.023% of the total number of 2D frames. When calibrating an XRD instrument by measuring the stress of the (113) reflection of a stress-free alumina powder sample, the instrument is considered calibrated when the sigma 11 and sigma 22 of the biaxial stress tensor are 0 ± 55 MPa, which is the standard deviation of the residual stress measurement.

[0049] Next, cubic (Al x Ti 1-x M y )C z N 1-z The biaxial stress state in the (200) plane can be measured. The biaxial stress state is measured using eight frames with different φ angles, while the sample in all frames is tilted 40° about the X axis (Ψ tilt), as previously mentioned. The rotation about the Z axis (angle φ) is 0° in the first frame and 315° in the eighth frame, with 45° increments between frames. The frame capture is not limited by time, but by the total number of frames, the value set in this work being 10,000,000. The actual total number of frames is typically less than this value, but is greater than 95,000,000. The detector and tube are set at an angle of 21.196°, with a cubic (Al) crystal somewhere in the middle of the detector. x Ti 1-x M y )C z N 1-zThe (200) reflection of the (200) reflection is captured. The stress calculation is performed over the γ range of 249° to 292°, while the 2θ range is set to ±1° relative to the observed maximum of the (200) reflection in the first frame (Ψ = 40°; φ = 0°). The 2θ range for stress measurement is 43.483° to 45.483°, as shown in Figure 5b. This range is then divided into 20 subranges with a peak rejection of 20% and a step of 0.1°. Peak evaluation is performed using the Pearson VII method. The crystallographic data used are 0.238 for the Poisson value and 330667 MPa for the Young's modulus. The value of |S1-S2| can be calculated as either |σ111-σ112| or |σ221-σ222|, where σ111 and σ221 are the values of σ11 and σ22 in the resulting biaxial stress tensor on the rake face, and σ112 and σ222 are the values of σ11 and σ22 in the resulting biaxial stress tensor on the flank face. The biaxial stress tensor is shown below.

[0050]

number

[0051] To illustrate how the maximum observed 2θ value intensity of the (200) reflection can be obtained from the total number of 2D frames, Figure 5a shows the cubic (Al x Ti 1-x M y )C z N 1-zFigure 5b shows a single XRD 2D frame for residual stress evaluation, with a total detector count of 9,475,328 frames and a total frame acquisition time of 156.98 seconds. Figure 5b shows the integration of this frame into a 1D spectrum. The integration was performed on a wedge (W in Figure 5a), encompassing a 2θ range from 41° to 46° and a gamma value of 249° to a value of 292°. The maximum of the integrated and observed peak is 2θ = 44.483° with an overall intensity of 23.2711 CPS. 23.2711 CPS x 156.98 seconds = 3,653 integrations. Of the total number of 2D frames, the maximum observed 2θ value of the (200) reflection, the Debye ring, DbR intensity shown in Figure 5a, is equal to (3,653 times / 9,475,328 times) × 100 = 0.038%, exceeding the 0.023% defined above.

[0052] The significance of the strong (200) reflection at Ψ=40° tilt is due to the cubic (Al x Ti 1-x M y )C z N 1-z However, the grains have a (111) texture and are scattered around the X axis enough to complete the dihedral angle between the (111) and (200) planes, along with a 40° Ψ tilt. Texture effects due to non-uniform intensity across the Debye rings can also be noted. See DbR in Figure 5a.

[0053] Nanohardness measurements were performed on an NHT3 nanoindentation tester manufactured by Anton Paar GmbH. The Berkovich diamond nanoindenter penetrated the specimen at a linear load rate of 120 mN / min up to a maximum load of 35 mN. Prior to testing, the specimens underwent surface treatment to render them suitable for such testing. Surface roughness significantly affects the nanoindenter penetration process. To achieve a suitable surface quality, the specimens were gently hand-polished on a soft fiber pad rotating at 150 rpm and then immersed in 50 nm of colloidal SiO2 for approximately 60 seconds. Figure 6a shows the specimen surface before polishing, and Figure 6b shows the same surface after polishing. The X in Figure 6b indicates a suitable location for nanoindentation measurements. The Vickers hardness values reported are the average of 20 indentations performed in close proximity to each other. The Poisson's ratio was set to 0.28. [Example]

[0054] While the present invention will be described in more detail by way of examples, it will be understood that the invention is not limited thereto.

[0055] Example 1 Cemented carbide substrates were prepared from cemented carbide powder having a composition of 89.5% WC, 10% Co and up to 0.5% (all by mass) of additional elements such as Cr3C2 or VC and sintered into indexable inserts such as CNMG 432 M3P having rake and flank faces that intersect to form a cutting edge.

[0056] The inserts were prepared by depositing a substrate and (Al) according to the industrial CVD method in a standard thermal furnace used for coating metal cutting tools, using the method disclosed in JP 2001-341008. x Ti 1-x Cl yA TiN layer was coated on the N layer. A 0.3 μm thick TiN layer was first formed on the substrate surface at 900°C using H2 carrier gas, TiCl4 gas, and N2 gas. Next, a TiAlN layer with a thickness of approximately 8 μm was formed at temperatures ranging from 700 to 900°C. The gases used were TiCl4 gas: 0.05 to 4.0 vol%, AlCl3 gas: 0.03 to 2.5 vol%, and NH3 gas: 0.05 to 3.0 vol%, and the carrier gases were H2 and N2 flowed into the reactor at pressures ranging from 2.7 to 15.9 kPa.

[0057] The coated inserts were blasted with SiC from a nozzle with a diameter of 0.8 mm at various blast flow angles (with a standard deviation of ±5°). The distance between the nozzle and the insert was 10 mm (±0.3 mm). The blasting of the rake face and flank face, i.e., the blasting time, blasting pressure, blasting medium, and blasting angle, resulted in different residual stresses on the rake face and flank face, respectively, and were selected so that the difference in residual stress was less than 500 MPa. Three examples of blasting parameters are shown below.

[0058] Three examples of metal cutting tools of the present invention that received inventive post-coating treatment A were blasted with SiC Fl80, a commonly used blasting media. The three examples are listed in Table 1.

[0059] [Table 1]

[0060] Four comparative samples of metal cutting tools were subjected to post-coating treatment B of spraying with SiC F180. The comparative samples are shown in Table 2.

[0061] [Table 2]

[0062] Example 2 After the blasting treatment, the residual stresses were measured on both the rake face and flank face using the one-axis tilt method for residual stress evaluation. The area detector is a BRUKER VANTEC-500 with a diameter of 140 mm. The results are shown in Table 1, and |S1-S2| for treatment B is shown in Table 2.

[0063] Nanohardness measurements were performed on an NHT3 nanoindentation tester manufactured by Anton Paar GmbH. Samples were gently hand-polished on a soft fiber pad rotating at 150 rpm, immersed in 50 nm colloidal SiO2 for approximately 60 seconds, and then penetrated with a Berkovich diamond at a linear load rate of 120 mN / min up to a maximum load of 35 mN. The reported Vickers hardness values are the average of 20 indentations on four samples performed in close proximity to each other. The Poisson's ratio was set to 0.28.

[0064] The results are shown in Table 3. The results of the Vickers hardness of Comparative Example 1 are shown in Table 4.

[0065] [Table 3]

[0066] [Table 4]

[0067] Example 3 In the CVD reactor, eight inserts with the shape of LNHT 1306 PNTR (Al 0.83 Ti 0.17 Cl 0.004 Four inserts were subjected to a post-coating treatment resulting in |S1-S2| of A2 in Table 1, i.e., A2i, A2ii, A2iii, and A2iv, and four comparative inserts with the same geometry were subjected to a post-coating treatment B resulting in |S1-S2| of B2 in Table 2, i.e., B2i, B2ii, B2iii, and B2iv.

[0068] In the dry milling test, specimens A2i, A2ii, B2i, and B2ii were tested on workpiece 1 made of cast iron grade GGG50. The rake face and cutting edge after the dry milling test are shown in Figures 3a to 3d, respectively, all of which are photographs taken with an optical microscope. The machining parameters were Vc = 230 m / min, f = 0.2 mm / rev, Ap = 4.0 mm, A e = 27 mm, and A e is the cutting width.

[0069] In the wet milling test, specimens A2iii, A2iv, B2iii, and B2iv were tested on workpiece 2 made of steel grade SAE4340. The rake faces and cutting edges of these specimens after the wet milling test are shown in Figures 4a to 4d, respectively, and all of these figures are photographs taken with an optical microscope. The parameters of the wet milling test were Vc = 200 m / min, f = 0.16 mm / rev, Ap = 2.0 mm, A e =40mm.

[0070] After normalizing the average tool life of these samples to 100%, the average tool life of samples A2i and A2ii, as shown in Figure 2a, is significantly increased by 230% over the average tool life of comparative samples B2i and B2ii, as shown in Figure 2b. The Y-axis in Figures 2a and 2b is the normalized average tool life (%). The rake face and cutting edge of sample A2i after 28 and 32 minutes, respectively, are shown in Figure 3a, and the rake face and cutting edge of sample B2i are shown in Figure 3c, with sample B2i in Figure 3c showing significant chipping.

[0071] After normalizing the average tool life of these samples to 100%, the average tool life of samples A2iii and A2iv is 385% greater than that of samples B2iii and B2iv shown in Figure 2b when milling SAE4340, as shown in Figure 2a. After 28 and 32 minutes of milling, the rake face and cutting edge of undamaged sample A2iii are shown in Figure 4a, and the rake face and cutting edge of undamaged sample A2iv are shown in Figure 4c, while after 28 minutes, sample B2iii in Figure 4b shows significant chipping and sample B2iv in Figure 4d shows catastrophic chipping.

Claims

1. A metal cutting insert comprising a base and a coating, The substrate is made of cemented carbide, cermet or ceramic, and the substrate has at least one rake face and at least one flank face that intersect to form a cutting edge, and the coating comprises one or more layers, the at least one layer having a composition comprising aluminum, titanium and nitrogen, and having a face-centered cubic lattice structure, and formula (Al ｘ Ti １－ｘ M ｙ ) C ｚ N １－ｚ Represented by, the stoichiometric coefficient of aluminum is 0.30 < x < 0.95, M is at least one element selected from the group consisting of Cl and Ar, the stoichiometric coefficient of M is 0 ≤ y < 0.01, preferably 0 ≤ y < 0.005, and the stoichiometric coefficient of carbon is 0 ≤ z < 0.

3. The aforesaid (Al ｘ Ti １－ｘ M ｙ )C ｚ N １－ｚ layer satisfies the relationship 10 < |S １ -S ２ | < 500 MPa, where S １ is the residual stress measured on the rake face, and S ２ is the residual stress measured on the flank face, characterized by a metal cutting insert.

2. | S １ |<3100 MPa, |S ２ | A metal cutting insert according to claim 1, wherein the pressure is <2800 MPa.

3. The metal cutting insert according to Claim 1, wherein 10 < |S1 -S2| < 350, the stoichiometric coefficient of aluminum is 0.80 < x < 0.90, |S1| < 2800 MPa, and |S2| < 2500 MPa.

4. The metal cutting insert according to claim 1, wherein y = 0 and z = 0.

5. The metal cutting insert according to claim 1, wherein the (Al x Ti 1-x My)C z N 1-z layer is a layer formed by chemical vapor deposition without plasma activation.

6. The metal cutting insert according to claim 1, wherein the coating comprises one or more further layers of carbides, nitrides, oxides, carbonitrides, oxynitrides, oxycarbides, oxycarbonitrides, borides, boronides, borocarbides, borocarbonitrides, borooxynitrides, boroic acid nitrides, boric acid carbides, or boroic acid carbonitrides of elements from the periodic system groups IVa to VIIa, and / or aluminum, mixed metal phases and phase mixtures of the compounds.

7. At least one of the further layers is the (Al ｘ Ti １－ｘ M ｙ ) C ｚ N １－ｚ A metal cutting insert according to claim 6, wherein the layer and the substrate are selected from the group consisting of TiN and TiCN.

8. The coating consists of the substrate and the (Al ｘ Ti １－ｘ M ｙ ) C ｚ N １－ｚ The metal cutting insert according to claim 6, comprising a TiN layer deposited on a layer, wherein the substrate is a cemented carbide.

9. The metal cutting insert according to claim 1, wherein the thickness of the coating is between 2 and 25 μm.

10. The metal cutting insert according to claim 6, wherein none of the one or more further layers are alumina layers.

11. The aforementioned (Al ｘ Ti １－ｘ M ｙ ) C ｚ N １－ｚ Layers are related | HV １ - HV ２ | <500, in the formula, HV １ This is the Vickers hardness measured on the rake surface, HV ２ The metal cutting insert according to claim 1, further characterized in that the hardness is measured on the flank surface.

12. 2300 < HV １ <4200 and 2400 ≤ HV ２ The metal cutting insert according to claim 11, wherein the value is <4000.

13. A method for manufacturing a metal cutting insert according to claim 1, A coating is applied to a substrate of cemented carbide, cermet, or ceramic by CVD, the coating having a total thickness of 2 to 25 μm and comprising at least one layer containing aluminum, titanium, and nitrogen, and having a face-centered cubic lattice structure, and the formula (Al ｘ Ti １－ｘ M ｙ ) C ｚ N １－ｚ Represented by (Al), the stoichiometric coefficient of aluminum is 0.30 < x < 0.95, M is at least one element selected from the group consisting of Cl and Ar, the stoichiometric coefficient of M is 0 ≤ y < 0.01, the stoichiometric coefficient of carbon is 0 ≤ z < 0.3, and the above (Al ｘ Ti １－ｘ M ｙ ) C ｚ N １－ｚ The layer has a thickness of 2 to 25 μm. After the coating is applied, the metal cutting insert is subjected to a spray treatment, and the spray pressure, spray duration, spray medium and / or spray angle of the spray treatment are as follows: ｘ Ti １－ｘ M ｙ ) C ｚ N １－ｚ Layer relationship 10 < | S １ -S ２ | Selected to satisfy <500 MPa, S １ is the residual stress measured on the rake surface, S ２ The method is such that is the residual stress measured on the flank surface.

14. A metal cutting system comprising an insert holder and at least one metal cutting insert as described in claim 1, wherein the at least one metal cutting insert is mounted on the insert holder.

15. The metal cutting insert according to claim 1, wherein at least one of the at least one rake face and the at least one flank face has been subjected to a post-coating treatment.

16. The metal cutting insert according to claim 1, wherein at least one of the at least one rake face and the at least one flank face has tensile residual stress.

17. The metal cutting insert according to claim 2, wherein the stoichiometric coefficient of aluminum is 0.67 < x < 0.95, -2200 ≤ S1 < 2400 MPa, and -1700 ≤ S2 < 1900 MPa.

18. The metal cutting insert according to claim 11, wherein 2900 ≤ HV1 < 3400 and 3000 ≤ HV2 < 3500.

19. The metal cutting insert according to claim 11, wherein 0 < |HV1 -HV2| < 100, 2600 ≤ HV1 < 3800, and 2700 ≤ HV2 < 3600.

20. The metal cutting insert according to claim 15, wherein a micrograph of at least one surface that has undergone post-coating treatment shows a "blurred" surface feature indicating plastic deformation of the outermost (Al x Ti 1-x My)C z N 1-z layer, where at least a portion of the uppermost vertices of the polyhedral grains are deformed in at least 20% of the micrograph area.

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