Cutting Tools

Abstract

The present invention relates to a cutting tool including a cemented carbide substrate, wherein the cemented carbide contains hard components in a metal binder. The hard components include WC, and the WC content in the cemented carbide is 80-96% by weight. The cemented carbide has a Ni content of 2.5-13% by weight, an Fe / Ni weight ratio of <1.5, and a Co / Ni weight ratio of <0.825. The cutting tool includes a rake face, a flank face, and a cutting edge therebetween. The hardness H is measured by Vickers indentation, and the crack resistance W is the ratio of the load to the total crack length of the crack at the corner of the Vickers indentation. The product of the rake face hardness H(rake) and the rake face crack resistance W(rake) for the cutting tool is H(rake) × W(rake) > 2000HV100 × N / μm.

Description

[Technical field]

[0001] The present invention relates to a cutting tool of a cemented carbide, the cemented carbide comprising a metal binder and a hard constituent comprising WC, the surface region of the cutting tool being more crack resistant than the bulk region of the tool. [Background technology]

[0002] Cutting tools for metal cutting applications typically include a substrate of cemented carbide. Cemented carbide is a material that exhibits both high hardness and toughness, and has been successfully used in cutting applications for decades. To further improve the performance of cutting tools, it is known to coat the tools with wear-resistant coatings. It is also known to treat cutting tools with a process known as post-treatment, which may include steps such as wet blasting, dry blasting, edge brushing and / or polishing. These post-treatment processes typically alter the surface roughness of the cutting tool and / or the residual stresses in the surface regions of the cutting tool.

[0003] The effect of shot peening on cemented carbide has been described by Wang et al., "Effect of shot peening on the residual stresses and microstructure of tungsten cemented carbide," Materials and Design 95, 2016, pp. 159-164. It has been shown that compressive residual stresses are induced in the surface layers of both Co and WC.

[0004] There is a continuing need to improve the life and performance of cutting tools to save time in production and reduce the risk of failure due to broken cutting tools. There is also a need to reduce the amount of Co in the cemented carbide and find alternative cemented carbides that can compete with conventional Co-containing cemented carbides in metal cutting performance. Summary of the Invention

[0005] The present invention aims to provide a cutting tool with improved wear resistance in metal cutting applications and also aims to provide a method for manufacturing the same. It is a further object of the present invention to provide a cutting tool with high resistance to chipping of the coating at the cutting edge. It is another object of the present invention to provide a turning tool with high resistance to chipping of the cutting edge and / or breakage of the cutting tool.

[0006] At least one of these objects is achieved by a cutting tool according to claim 1 and by a method according to claim 12. Preferred embodiments are given in the dependent claims.

[0007] The present invention relates to a cutting tool including a substrate of cemented carbide, the cemented carbide including a hard component in a metal binder, the hard component including WC, the WC content in the cemented carbide being 80-96% by weight, the cemented carbide having a Ni content of 2.5-13% by weight, a Fe / Ni weight ratio of <1.5, and a Co / Ni weight ratio of <0.825, the cutting tool including a rake face, a flank face, and a cutting edge therebetween, the hardness H[HV100] being measured by a Vickers indentation made under a load of 100×9.81 N, and the crack resistance W being: Defined as TIFF0007638286000001.tif14170, P is the Vickers hardness indentation load [N], TIFF0007638286000002.tif8170 relates to a cutting tool, wherein the average crack length [μm] of each crack formed at the corner of the Vickers hardness indentation, and the product of the rake face hardness H(rake) and the rake face crack resistance W(rake) is H(rake)×W(rake)>2000HV100×N / μm, preferably >3000HV100×N / μm, more preferably >3500HV100×N / μm.

[0008] Typically, for the most technically advanced composite materials, such as cemented carbide materials, improving toughness is related to a decrease in hardness. It was surprisingly found that by processing the material within the specific composition ranges described herein, the crack resistance was improved without losing hardness. One way to show the combination of toughness and resistance to plastic deformation (i.e., hardness) for cutting tool applications is by yielding the product of hardness H and crack resistance W, i.e., H×W. The higher H×W is, the more resistant the cutting tool is to both crack formation and plastic deformation. This high value of H×W > 2000 HV100×N / μm, preferably > 3000 HV100×N / μm, more preferably > 3500 HV100×N / μm cannot be achieved by varying common material design variables such as particle size, volume fraction of phases, etc.

[0009] In one embodiment of the present invention, the cemented carbide contains x wt% of Ni, y wt% of Fe, and z wt% of Co, and 5 < x + y + z < 13. Cemented carbides with a binder content within this range have a good combination of toughness and resistance to plastic deformation suitable for use in metal cutting tools. Depending on the specific metal cutting application, the amount of binder can be optimized by those skilled in the art.

[0010] In one embodiment of the present invention, the relationship between the hardness H(rake) of the rake face of the cutting tool and the hardness H(flank) of the flank face of the cutting tool is 0.9 < H(rake) / H(flank) < 1.1. High crack resistance can be achieved by reducing the hardness on either the rake face or the flank face, but this will reduce the resistance to plastic deformation, which will have an adverse effect on the cutting tool life time. High hardness on both faces is advantageous for the wear resistance of the cutting tool.

[0011] In one embodiment of the present invention, the relationship between the hardness H(rake) of the rake face of the cutting tool and the hardness H(bulk) of the bulk region of the cutting tool is 0.9 < H(rake) / H(bulk) < 1.1. High hardness in both the surface region and the bulk of the cutting tool is advantageous for the wear resistance of the cutting tool in metal cutting applications.

[0012] In one embodiment of the present invention, the crack resistance W measured on the rake face of the cutting tool is W(rake) and the crack resistance W measured on the flank face of the cutting tool is W(flank), where W(rake) / W(flank)>2, preferably>2.5. Cracks occurring during metal cutting usually occur on the rake side of the cutting tool, therefore good crack resistance on the rake face is advantageous for metal cutting applications. Furthermore, if only the rake face is shot peened and the flank side is slightly less important, the cutting tool manufacturing process becomes relatively simple.

[0013] In one embodiment of the invention, the crack resistance W measured at the rake face of the cutting tool is W(rake) and W measured at the bulk area of ​​the cutting tool is W(bulk), where W(rake) / W(bulk)>2, preferably>2.5, more preferably>3. Cracks occurring during metal cutting usually occur on the rake side of the cutting tool, therefore good crack resistance on the rake face is advantageous for metal cutting applications. Cracks usually appear on the surface of the cutting tool and not in the bulk, therefore high crack resistance in the surface area is advantageous.

[0014] In one embodiment of the invention, the hardness H(rake) of the rake face of the cutting tool is >1300HV100, preferably >1400HV100, more preferably >1500HV100. High hardness in the surface areas of the cutting tool, especially in the areas of the cutting tool that contact the workpiece during metal cutting applications, is advantageous in that the wear resistance of the cemented carbide is improved. Furthermore, the ceramic coating applied on the substrate can survive longer on the harder substrate, thereby improving the life of the cutting tool.

[0015] In one embodiment of the present invention, the crack resistance of the rake face of the cutting tool is W(rake)>1.5N / μm, preferably>2.0N / μm, more preferably>2.2N / μm. The cracks generated during metal cutting limit the life of the cutting tool. Therefore, improving the crack resistance of the rake face will increase the tool life of the cutting tool in metal cutting applications.

[0016] In one embodiment of the invention, the residual stress measured in the surface area of ​​the rake face of the cutting tool is compressive and is >1500 MPa, preferably >2000 MPa, more preferably >2200 MPa, and the stress measurement is by sin sieving using X-ray diffraction and the (211) reflection of WC. 2 The compressive stress is preferably <3500 MPa, more preferably <3000 MPa. The compressive residual stress inhibits the formation of cracks. Therefore, improving the crack resistance of the rake face will increase the tool life of the cutting tool in metal cutting applications.

[0017] In one embodiment of the present invention, the cemented carbide contains 2.5-7 wt% Ni, 0.5-3 wt% Fe, 0.1-0.5 wt% Co, preferably the cemented carbide contains 2.5-5.5 wt% Ni, 0.5-3 wt% Fe, 0.1-0.3 wt% Co, and the balance WC.

[0018] In one embodiment of the invention, the cemented carbide comprises one or more of Ti, Nb, Ta, Mo, Re, Ru, N, Cr, Zr, V, N, preferably the cemented carbide comprises 5-7 wt% Ni, 0.5-1.5 wt% Fe, 0.2-0.4 wt% Co, and one or more of Ti, Nb, Ta, Mo, Re, Ru, Cr, Zr, V, N, more preferably the cemented carbide comprises 1.5-2.5 wt% Ti, 0.25-0.75 wt% Nb, 2.5-3.5 wt% Ta, 0.05-0.2 wt% N, 5-7 wt% Ni, 0.5-1.5 wt% Fe, 0.2-0.4 wt% Co, and balance WC. This particular composition is optimal for forming a cubic carbide free surface zone advantageous for steel turning applications. Cutting tools with cubic carbide free surface zones have improved crack growth resistance while maintaining good bulk plastic deformation resistance.

[0019] The invention further relates to a method of treating a cutting tool comprising a cemented carbide substrate, said cemented carbide comprising a hard component in a metal binder, said hard component comprising WC, said WC content in the cemented carbide being 80-96% by weight, said cemented carbide having a Ni content of 2.5-13% by weight, a Fe / Ni weight ratio of <1.5 and a Co / Ni weight ratio of <0.825, said cutting tool (1) comprising a rake face (2), a flank face (3) and a cutting edge therebetween, said shot peening being performed at least on the rake face (2), said method comprising the step of shot peening the rake face of the cutting tool. It has been surprisingly found that shot peening on this particular cemented carbide composition improves the crack resistance of the surface whilst hardness is maintained, thereby improving the combination of hardness and crack resistance.

[0020] In one embodiment of the invention, shot peening is carried out at a temperature of 100-600° C., preferably 200-550° C., more preferably 300-500° C. Shot peening at this elevated temperature has surprisingly been found to improve the properties of certain hard metals to previously unreached levels of crack resistance and / or residual stress.

[0021] The shot peening of the present invention is carried out in one embodiment at an elevated temperature, which is defined herein as the temperature at which the material being shot peened (part of the cutting tool) is during shot peening. The elevated temperature of the part of the cutting tool can be produced using several methods, e.g., induction heating, resistance heating, preheating on a hot surface / oven, laser heating, etc. The cutting tool can alternatively be heated in a separate step prior to the shot peening step.

[0022] The temperature is suitably measured on the substrate by any method suitable for measuring temperature. Preferably, an infrared temperature measuring device is used.

[0023] A portion of the substrate is subjected to shot peening at said temperature. It has surprisingly been found that treating the cutting tool with shot peening when the cutting tool is heated improves its crack resistance in the surface region, which is an important property for improving the life of the cutting tool.

[0024] In one embodiment of the invention, the edge radius ER of at least a part of the cutting edge is between 10 μm and 50 μm, preferably between 20 μm and 40 μm. It has surprisingly been found that cutting tools made by this method perform well with this ER.

[0025] In one embodiment of the present invention, shot peening is performed with ceramic beads, preferably beads containing ZrO2, SiO2, and Al2O3. Depending on the type of media, one skilled in the art can optimize the level of energy delivered to the cutting tool, thereby optimizing the shot peening process.

[0026] In one embodiment of the present invention, shot peening is performed with beads having an average diameter of about 50-200 μm. If the beads are too large, the risk of damaging the cutting edge increases. If the beads are too small, the energy and impact delivered from the medium to the substrate becomes barely noticeable. The impact or energy from the beads during shot peening should not be too high, as this increases the risk of damaging the surface and cutting edge of the cutting tool. The impact or energy from the beads should not be too low, as the technical effect is not achieved then. The appropriate size of the beads is related to the material of the beads and is selected by the person skilled in the art. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a general view of a cutting tool insert 1, which comprises a rake face 2, a flank face 3 and a cutting edge provided therebetween. [Diagram 2]1 is a general view of a cross section of a cutting edge, the edge radius ER is indicated and furthermore the cutting edge width A is indicated diagrammatically. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] definition "Cemented carbide" is a material that contains hard components dispersed in or embedded in a continuous metal binder, forming a skeleton. The hard components primarily contain WC. This type of material combines high toughness from the metal binder with high hardness from the hard components, making it suitable as a substrate material for metal cutting tools.

[0029] "Composition of" or "content in" a cemented carbide means herein the average composition or average content in a cemented carbide substrate. For example, since a cutting tool is at least a few mm in size, a gradient in a surface zone, e.g. 15-30 μm from the surface to the bulk of the substrate, with a locally higher metal binder content, does not change the average composition of the cemented carbide substrate of the cutting tool.

[0030] The "metal binder" of a cemented carbide can include elements that are dissolved in the metal binder during sintering, such as W and C from WC. Other elements can also be dissolved in the binder, depending on what types of hard constituents are present.

[0031] By "cutting tool" is meant herein a cutting tool for metal cutting applications, for example an insert, an end mill, or a drill. The field of application can be turning, milling, or drilling.

[0032] "ER" is an edge radius value intended to indicate edge sharpness. A higher ER value represents a rougher cutting edge profile, while a lower ER value represents a sharper cutting edge.

[0033] ER is defined herein as the value calculated according to: - Place the cutting tool on a flat surface on its seat or on a corresponding surface of the cutting tool. - Align the first surface along the side of the cutting tool perpendicular to the flat surface, in contact with the edge, for example measuring along the flank 3 of the cutting tool 1. - aligning a second surface parallel to said flat surface and intersecting said first surface at an intersection point, said second surface being measured at a tangent point tangential to an edge, e.g. said second surface is aligned along the rake face 2 of a cutting tool 1.

[0034] The value "ER" is equal to the distance between the intersection of the first and second surfaces and the point of contact between the first surface and the cutting tool proximate the edge, see FIG.

[0035] "Shot blasting" as used herein refers to a process using abrasive particles where material is removed from a treatment surface, typically by abrasion. Shot blasting is well known in the art of cutting tools and is known to introduce residual stresses, for example, in coatings on cutting tools.

[0036] "Shot peening" as used herein means that the surface of a cutting tool is subjected to a media containing particles, e.g., beads, which are non-abrasive and typically circular. The media can be beads of a hard material, e.g., oxide, steel, or cemented carbide.

[0037] The term "bulk" as used herein means the innermost (center) portion of the cutting tool.

[0038] The term "surface region" as used herein means the outer portion of the substrate that is affected by the shot peening process disclosed herein. Further embodiments of the invention

[0039] In one embodiment of the invention, the WC grain size is uniform throughout the substrate. Non-uniform WC grain size can lead to crack initiation sites due to differences in thermo-mechanical properties of different zones.

[0040] In one embodiment of the present invention, the average WC grain size is 0.2-10 μm, preferably 0.5-3 μm. In this range, the grain size of WC is optimal for cemented carbide for metal cutting inserts. Depending on the metal cutting application, the WC grain size can be optimized by those skilled in the art.

[0041] In one embodiment of the invention, the cemented carbide further comprises a cubic phase, sometimes referred to as gamma phase, which is a solid solution of cubic carbides and / or carbonitrides of one or more elements selected from Ti, Ta, Nb, Hf, Zr, V and Cr. The amount of cubic phase, in area %, is suitably 2-25%, preferably 3-15%. This can be measured in different ways, but one way is to carry out image analysis of either light optical microscopy images or scanning electron microscopy (SEM) photographs of cross sections of the substrate to calculate the average proportion of gamma phase.

[0042] In one embodiment of the invention, the cemented carbide comprises a cubic phase and a binder phase-rich surface zone free of cubic phase. The thickness of the surface zone is suitably 2-100 μm, preferably 3-70 μm, more preferably 8-35 μm. The thickness is determined by measurements on SEM or LOM images of a cross section of the substrate. These measurements should be made in an area where the substrate surface is reasonably flat, i.e. not close to the edge, at least 0.3 mm from the cutting edge or nose, etc., to obtain a true value. The boundary between the surface zone and the bulk is determined by the presence or absence of a cubic phase, which is usually quite distinct, when observing a cross section of the substrate in an SEM or LOM image. The thickness is determined by the distance between the surface and the boundary between the surface zone and the bulk. "Binder-rich" means in this specification that the content of the binder phase in the surface zone is suitably 1.05-1.65 times, preferably 1.1-1.5 times, the content of the binder phase in the bulk. The binder phase content in the surface zone is suitably measured at a depth half the total thickness / depth of the surface zone. Any measurements made in the bulk should be made in an area that is not too close to the surface zone. This means that any measurements made on the bulk microstructure herein should be made at a depth of at least 200 μm from the surface.

[0043] A surface zone free of cubic phase means herein that the surface zone is free of cubic phase particles or contains very few, i.e. less than 0.5% by area, of cubic phase particles.

[0044] In one embodiment of the invention, the cutting tool is provided with a coating, which may be a color layer or a wear-resistant coating.

[0045] In one embodiment of the present invention, the coating has a thickness of 2 to 20 μm, preferably 5 to 10 μm.

[0046] In one embodiment of the invention, the coating is a CVD coating or a PVD coating, preferably the coating comprises one or more layers selected from TiN, TiCN, TiC, TiAlN, Al2O3, and ZrCN. Preferably the coating is a CVD coating comprising a TiCN layer and an Al2O3 layer.

[0047] In one embodiment of the invention, the coating is a CVD coating comprising an inner TiCN layer and an outer α-Al2O3 layer.

[0048] In one embodiment of the invention, the cemented carbide substrate is provided with a wear resistant PVD coating, suitably a nitride, oxide, carbide or mixture thereof with one or more of Al, Si and elements selected from groups 4, 5 and 6 of the periodic table.

[0049] In one embodiment of the invention, the cutting tool comprises a rake face, a flank face and a cutting edge therebetween, said shot peening being performed at least on the rake face. Rake face peening is advantageous in that the work material impacts the cutting tool during the cutting operation and therefore the mechanism during peening that affects the substrate is applied at the rake face, which is applied at the relevant area or volume of the substrate. For many cutting tool geometries this means treating several cutting edges simultaneously, so applying shot peening on the rake face is even more advantageous.

[0050] In one embodiment of the invention, shot peening is performed with a heated cutting tool and the method includes a step prior to shot peening, where said cutting tool is heated.

[0051] In one embodiment of the invention, the method further comprises the step of shot blasting at least a portion of the cutting tool, preferably the portion including at least a portion of the cutting edge or a region proximate to the cutting edge.

[0052] In one embodiment of the invention, the shot blasting step is performed after the shot peening. Heating during shot peening can reduce some of the positive effects from shot blasting, such as the induction of residual stresses in the coating, so by choosing to perform the shot peening before the shot blasting, both positive effects can be maintained.

[0053] In one embodiment of the invention, shot blasting and shot peening are performed on the same part of the cutting tool, which is advantageous during large scale production, for example, due to more effective loading of the cutting tool.

[0054] In one embodiment of the invention, the shot peening is performed with the shot direction perpendicular to the surface of the cutting tool. Perpendicular shot peening is advantageous in that the depth of the substrate affected is greatest when the heated shot peening is in this direction.

[0055] In one embodiment of the invention, the cutting tool 1 is an insert, preferably a milling insert or a turning insert.

[0056] The shot peening process according to the present invention may also be combined with other process steps known in the art of making cutting tools, such as, for example, brushing, abrading, wet blasting, dry blasting, etc. EXAMPLES

[0057] In the following, exemplary embodiments of the present invention are disclosed in more detail in comparison with the reference embodiment: Coated and uncoated cutting tools (inserts) were prepared and analyzed. EXAMPLES

[0058] (Sample Preparation) Cemented carbide cutting tools were prepared by forming substrates from raw materials to reach a raw material composition according to Table 1. Fe and Ni were added as metals (Ni 0.85 , Fe 0.15 Ta and Nb were added as TaC and (Ta 0.6 , Nb 0.4 )C. Ti and N were added as (Ti 0.5 , W 0.5 )C and Ti(C 0.5 , N 0.5 ) was added. C, which compensates for carbon lost during milling and sintering, was added as carbon black. WC was added as raw material "WC-1" or "WC-2". The average particle size (FSSS) for WC-1 was 1.24-1.44μm, and for WC-2, 5.5-6.3μm. The amount of each raw material was appropriate and is shown based on the total dry powder weight, with the balance being WC. The substrates were manufactured according to conventional methods including milling, spray drying, pressing, and sintering. Insert-type CNMG120408-PM cutting tools were formed. For example, the relative contents of Ni, Fe, Co, and even WC are maintained from the raw dry powder to the sintered cemented carbide. TIFF0007638286000003.tif30170

[0059] During sintering of the substrate 3, a cubic carbide-free zone of about 20 μm was formed in the surface zone of the substrate.

[0060] The substrate 3 was coated in a CVD coating process to deposit the layers TiN / TiCN / α-Al2O3 / TiN. The total coating thickness was about 14 μm. The total thickness of the lower TiN and TiCN is about 9 μm.

[0061] Cutting tools of all types of substrates were shot peened at room temperature of 25° C. and at an elevated temperature of 500° C. to form comparative samples 1-3 and inventive samples 1-3.

[0062] The shot peening of the samples was carried out in an AUER manual blast cabinet ST700PS machine. A blasting medium of ceramic beads with a spherical shape and an average diameter of about 100 μm (medium Microblast® B120) was used. The particle size of the ceramic beads was 63-125 μm. The ceramic beads have a composition of 60-70% ZrO2, 28-33% SiO2, and <10% Al2O3. The shotgun pressure was set at 5 bar, the working time was set at 20 seconds, the nozzle diameter was 8 mm, and the separation distance was 100 mm. The peening was applied perpendicular to the rake face of the cutting tool. In the case of heated shot peening, the cutting tool was heated by an induction coil heater before shot peening, and the temperature of the cutting tool was measured by a temperature sensor. The induction heater was a Rimac induction heater of 1.5 kW.

[0063] The cutting edge of the cutting tool after these post-treatments had an ER of about 40 μm. Vickers measurement

[0064] Vickers impressions were made on the rake face of the cutting tool and on the cross section of the cutting tool. Vickers impressions can also be made on the flank side.

[0065] Uncoated samples were gradually polished to achieve a suitable surface for crack length measurement. Samples were polished using 0.25 μm diamond paste on paper and polished using 0.25 μm diamond paste on a 20 mm diameter felt wheel either by hand or using a Gatan Dimple Grinder Model 656 at medium speed and a load of 35 g. Polishing was continued until a surface was achieved that exhibited sufficient polished areas for subsequent crack length measurement.

[0066] The coated samples were polished using standard methods to expose the TiCN layer on the rake face of the cutting tool. Bulk samples were prepared by cutting the insert perpendicular to the rake face using a diamond wheel, followed by polishing with 9 μm diamonds dispersed in oil on paper, then 1 μm diamonds dispersed in oil.

[0067] The Vickers hardness of the polished samples was measured using a programmable hardness tester (KB30S by KB Pruftechnik). Measurements were calibrated to HV100 using test blocks from the Euro Products Calibration Laboratory (UK). Vickers hardness was measured according to ISO EN6507.

[0068] Vickers hardness measurements were performed by programming the hardness tester to make an indentation at a certain location. An indentation was then made using a specific load. At least two parallel HV100 indentations were made at a distance of at least 1.5 mm apart, and the results shown are average values.

[0069] The crack length at each corner of the Vickers indentation was analyzed and measured with an Olympus BX51M light optical microscope equipped with a camera and computer. The specimen and camera were aligned so that the diagonals of the Vickers indentation were horizontal and vertical on the computer screen. A magnification of at least 100x was used. If it was difficult to find the tip of the crack, a higher magnification was applied to locate the tip of the crack before measuring. The two diagonals of each indentation were measured and the crack was measured as the projection of the extended diagonal of the indentation from each corner of the indentation to the tip of the crack. TIFF0007638286000004.tif79170Residual stress measurement

[0070] Using X-ray diffraction, the so-called sin 2 The residual stress of the aforementioned samples was determined by the Ψ method. In this method, the deviation in lattice spacing d (and therefore strain) is measured as a function of the sample tilt angle Ψ. The residual stress is calculated as the function of strain versus sin 2 It is obtained from the linear slope of the Ψ curve. Residual stress is converted from the strain value by using the X-ray elastic constants.

[0071] XRD measurements were performed using an IμS microfocus radiation source (CuK). αMeasurements were performed on a Davinci-designed Bruker DiscoverD8 diffractometer equipped with a 1 / 4 Euler cradle (radiation, λ = 1.5418 Å), a Vantec-500 area detector and a 1 / 4 Euler cradle. The (211) reflection of WC located at 117.32° 2θ was used for the strain measurements. Residual stress measurements were performed in 1-4 angular directions: Φ: 0°, 90°, 180°, 270°, and for each Φ direction, 10 equidistant Ψ angles (0°-50°) were measured with a measurement time of 400 s. A collimator with a diameter of 1.0 mm was used in all measurements.

[0072] The resulting residual stress was obtained from the strain data by using the X-ray elastic constants for WC, Bragg peak (211). The X-ray elastic constants were calculated from the Poisson's ratio ν=0.191 and Young's modulus=717.360 GPa.

[0073] The sample was attached to a sample holder with adhesive tape.

[0074] XRD data were analyzed with the software DIFFRAC EVA (Bruker) and High Score Plus (Malvern Panalytical). The software LEPTOS7 (Bruker) was used for residual stress analysis. TIFF0007638286000005.tif77170

[0075] Although the present invention has been described in connection with various exemplary embodiments, it is understood that the invention is not limited to the disclosed exemplary embodiments, but is intended to encompass various modifications and equivalent arrangements within the scope of the appended claims. Moreover, it should be recognized that any disclosed form or embodiment of the present invention may be incorporated into any other disclosed or described or suggested form or embodiment as a matter of general design choice. Accordingly, the invention is limited only as indicated by the scope of the appended claims attached hereto.

Claims

1. A cutting tool comprising a substrate of cemented carbide, the cemented carbide comprising a hard component in a metal binder, the hard component comprising WC, the WC content in the cemented carbide being 80-96 wt%, the cemented carbide having a Ni content of 2.5-13 wt%, a Fe / Ni weight ratio of <1.5, and a Co / Ni weight ratio of <0.825, the cutting tool comprising a rake face, a flank face, and a cutting edge therebetween, the hardness H[HV100] being measured by Vickers indentation made at a load of 100 x 9.81 N, and the crack resistance W being: It is defined as P is the Vickers hardness indentation load [N], is the average crack length [μm] of each crack formed at the corner of the Vickers hardness indentation, the product of the rake face hardness H(rake) and the crack resistance of the rake face W(rake) is 3000HV100×N / μm<H(rake)×W(rake)<7000HV100×N / μm, and W measured in the bulk area of ​​the cutting tool is W(bulk) and 2.5<W(rake) / W(bulk)<4.

2. 2. The cutting tool of claim 1, wherein the cemented carbide comprises x wt % Ni, y wt % Fe, and z wt % Co, where 5<x+y+z<13.

3. 3. The cutting tool according to claim 1, wherein a relationship between a hardness H(rake) of the rake face of the cutting tool and a hardness H(flank) of the flank of the cutting tool satisfies 0.9<H(rake) / H(flank)<1.

1.

4. 4. The cutting tool according to claim 1, wherein the relationship between the hardness H(rake) of the rake face of the cutting tool and the hardness H(bulk) of the bulk region of the cutting tool is 0.9<H(rake) / H(bulk)<1.

1.

5. 5. A cutting tool according to claim 1, wherein the crack resistance W measured on the rake face of the cutting tool is W(rake) and W measured on the flank face of the cutting tool is W(flank), such that W(rake) / W(flank)>2.

6. 6. A cutting tool according to any one of claims 1 to 5, wherein the hardness H(rake) of the rake face of the cutting tool is >1300 HV100.

7. A cutting tool according to any one of claims 1 to 6, wherein the crack resistance of the rake face of the cutting tool is W(rake) > 1.5 N / μm.

8. Residual stresses measured in the surface area on the rake face of the cutting tool are compressive and >1500 MPa, and stress measurements were performed using X-ray diffraction and sin 2+ 1 + ... ２ The cutting tool according to any one of claims 1 to 7, which is made by the Ψ method.

9. 9. A cutting tool according to any one of claims 1 to 8, wherein the cemented carbide comprises 2.5-7 wt.% Ni, 0.5-3 wt.% Fe, 0.1-0.5 wt.% Co and balance WC.

10. 10. A cutting tool according to any one of the preceding claims, wherein the cemented carbide comprises one or more of Ti, Nb, Ta, Mo, Re, Ru, Cr, Zr, V, N and balance WC.

11. The cutting tool according to any one of claims 1 to 10, wherein the edge radius ER of at least a part of the cutting edge is between 10 μm and 50 μm.

12. 1. A method of manufacturing a cutting tool including a cemented carbide substrate, comprising: the cemented carbide comprises hard components in a metal binder, the hard components comprising WC, the content of WC in the cemented carbide being 80-96 wt%, the cemented carbide having a Ni content of 2.5-13 wt%, a weight ratio of Fe / Ni < 1.5 and a weight ratio of Co / Ni < 0.825, the cutting tool (1) comprises a rake face (2), a flank face (3) and a cutting edge therebetween, the shot peening being performed on at least the rake face (2), the method comprising the step of shot peening the rake face of the cutting tool, the shot peening being performed at a temperature of 100-600°C.

13. The method of claim 12, wherein the shot peening is performed with ceramic beads.

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