Cemented carbide, manufacturing method thereof, and cutting tool

Abstract

Provided is a cemented carbide in which both wear resistance and fracture resistance have been enhanced by improving both hardness and toughness. According to an aspect of the present invention, provided is a cemented carbide comprising a hard phase and a binder phase, wherein the hard phase includes WC, the binder phase includes Co and a transition metal (excluding Co), and the saturation magnetization of the cemented carbide is 75-85% in accordance with Equation 1 below. [Equation 1]: Saturation magnetization (%) of cemented carbide = {[M1(emu)] / [M2(emu / g)×M3(g)]} In Equation 1, M1 is the saturation magnetization (emu) of the cemented carbide, M2 is the theoretical saturation magnetization (emu / g) of Co, and M3 is the Co content (g) in the cemented carbide.

Description

Superhard alloy, its manufacturing method and cutting tool

[0001] The present invention relates to a superalloy, and more particularly, to a superalloy, a method for manufacturing the same, and a cutting tool.

[0002] Cemented carbide is a representative material for cutting tools and is widely used in the form of a sintered alloy composed of a hard phase mainly composed of WC and a bonding phase mainly composed of Co.

[0003] Meanwhile, the demand for improved performance of cutting tools has been continuously raised, and to meet this demand, research is being conducted to improve the mechanical properties of cemented carbide materials.

[0004] For example, patent document 1 (JP 5152770 B2) discloses a superalloy in which the FCC / HCP ratio of the Co phase is increased by adding Cr based on the combined phase crystal structure, thereby improving the tensile strength, compressive strength, and fatigue strength.

[0005] In addition, Patent Document 2 (JP 4537501 B2) describes a method for making a Co crystal structure 0≤I by immersing and rapidly cooling a sintered body in a liquid. (Co HCP) / I (Co FCC) A super-hard alloy is disclosed that has improved impact strength by controlling the lattice constant to a range of ≤0.1 and simultaneously increasing the lattice constant to 3.570 or more.

[0006] Additionally, Patent Document 3 (JP 6972508 B2) discloses a superalloy having excellent fatigue resistance and wear resistance by controlling the Co phase lattice constant of the superalloy to 3.580 Å to 3.610 Å and the saturation magnetization to 40% to 58%.

[0007] The purpose of the present invention is to provide a superalloy having improved wear resistance and fracture resistance by simultaneously improving hardness and toughness.

[0008] Another object of the present invention is to provide a method for manufacturing a superalloy capable of simultaneously improving wear resistance and fracture resistance.

[0009] Another object of the present invention is to provide a cutting tool with an extended life under cutting conditions that become more severe as workpiece materials become more diverse.

[0010] The purposes of the present invention are not limited to those mentioned above, and other unmentioned purposes and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof described in the specification.

[0011] According to a first aspect of the present invention for achieving the above object, a superalloy is provided, which is composed of a hard phase and a binder phase, wherein the hard phase includes WC, the binder phase includes Co and a transition metal (however, Co is excluded), and the superalloy has a saturation magnetization of 75 to 85% according to the following formula 1.

[0012] [Formula 1]

[0013] Saturation magnetization rate of cemented carbide (%) = {[M1(emu)] / [M2(emu / g)×M3(g)]}

[0014] In the above equation 1, M1 is the saturation magnetization (emu) of the cemented carbide, M2 is the theoretical saturation magnetization (emu / g) of Co, and M3 is the content (g) of Co in the cemented carbide. That is, the saturation magnetization (%) of the cemented carbide means the ratio of the saturation magnetization (emu) of the cemented carbide to the theoretical saturation magnetization (emu) of Co included in the cemented carbide. In some examples, the saturation magnetization (emu) of the cemented carbide can be measured using a known magnetic property measuring device. In addition, the theoretical saturation magnetization of Co can be a known value.

[0015] According to the second aspect of the present invention, in the first aspect, the content of Co may be 5 to 15 wt% based on the total weight of the superalloy.

[0016] According to a third aspect of the present invention, in the first or second aspect, the content of the transition metal may be 0.5 to 3.5 wt% based on the total weight of the superalloy.

[0017] According to a fourth aspect of the present invention, in any one of the first to third aspects, the transition metal may include at least one of Ru, Re, Pd, Ir, Rh, Os and Pt, and specifically may include any one selected from the group consisting of Ru, Re and combinations thereof.

[0018] According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a cemented carbide can be provided in which, based on XRD (X-ray diffraction) analysis, in a diffraction pattern in a section where 2θ is 40 to 50°, a peak originating from the HCP (002) plane of Co does not exist. For example, based on XRD (X-ray diffraction) analysis, a cemented carbide can be provided in which, in a diffraction pattern in a section where 2θ is 40 to 50°, a peak originating from the HCP (010) plane of Co exists. For example, based on XRD (X-ray diffraction) analysis, a cemented carbide can be provided in which, in a diffraction pattern in a section where 2θ is 40 to 50°, a peak originating from the FCC (111) plane of Co exists.

[0019] According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the superalloy may not contain glassy carbon.

[0020] According to a seventh aspect of the present invention, a cemented carbide alloy is provided, which is composed of a hard phase and a binder phase, wherein the hard phase includes WC, the binder phase includes Co and a transition metal (however, Co is excluded), and, based on XRD (X-ray diffraction) analysis, the intensity of a peak originating from an FCC (111) plane of the Co is higher than the intensity of a peak originating from an HCP (010) plane of the Co. In this case, the seventh aspect of the present invention may be characterized by at least one of the first to sixth aspects.

[0021] According to an eighth aspect of the present invention, there is provided a method for manufacturing a cemented carbide according to any one of the first to seventh aspects, comprising: (S1) preparing a mixed powder comprising WC powder, Co powder, and a transition metal powder (excluding WC powder and Co powder); (S2) filling the mixed powder with a binder into a mold and then molding it to manufacture a molded body; and (S3) sintering the molded body to manufacture a cemented carbide, wherein step (S3) comprises: (a) debinding the molded body in an inert gas atmosphere for 6 to 8 hours; (b) heating the debinded molded body to 1,000 to 1,250°C under a vacuum atmosphere and maintaining it at the highest temperature for 4 to 6 hours; (c) heating the body to 1,350 to 1,380°C under a vacuum atmosphere and maintaining it at the highest temperature for 50 to 80 minutes to manufacture a sintered body; And (d) a step of cooling the sintered body from the highest temperature to 40 to 50°C in a vacuum atmosphere to manufacture the superalloy; a method for manufacturing a superalloy is provided.

[0022] In some examples, the particle size of the WC powder may be 0.5 to 4.0 μm or 1.0 to 3.1 μm.

[0023] In some examples, the mixed powder may further include at least one of a carbide powder, a nitride powder, and a carbonitride powder, and one or more of metals of Groups 4, 5, and 6 of the periodic table.

[0024] According to a ninth aspect of the present invention, a cutting tool is provided, comprising: a substrate including a superalloy according to any one of the first to seventh aspects;

[0025] According to a tenth aspect of the present invention, a cutting tool can be provided that further includes a coating film on the substrate in the ninth aspect.

[0026] In some examples, the thickness of the coating film may be 1 to 7 μm.

[0027] The solutions to the above problems do not enumerate all features of the present invention. The various features of the present invention, along with their corresponding advantages and effects, can be understood in more detail by referring to the detailed description below.

[0028] According to one aspect of the present invention, a superalloy having improved wear resistance and fracture resistance can be realized by simultaneously improving hardness and toughness.

[0029] According to another aspect of the present invention, a cutting tool with an extended life can be implemented under cutting conditions that become more severe as the workpiece material becomes more diverse.

[0030] In addition to the aforementioned effects, specific effects of the present invention are described below along with the specific details for implementing the invention. Furthermore, the effects of the present invention are not limited to the effects described above and can be readily realized by the embodiments and combinations thereof described in the specification.

[0031] Figure 1 shows the XRD analysis results for the section where 2θ is 40° to 50° in the superhard alloy according to Comparative Examples 1 and 2 and Example 2.

[0032] Figure 2 shows the XRD analysis results for the section where 2θ is 40° to 55° in the superhard alloy according to Example 2 and Comparative Example 2.

[0033] Figure 3 is an enlarged view of the XRD analysis results for the section where 2θ is 42° to 45° in the superhard alloy according to Example 2 and Comparative Example 2.

[0034] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0035] The terms "comprise" and / or "comprising" as used herein specify the presence of stated features, steps, numbers, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, numbers, operations, elements, elements and / or groups thereof.

[0036] When multiple embodiments are described in this specification, the effects of the present invention may be defined to include not only the operational effects derived from each embodiment itself, but also the effects resulting from the organic combination of the embodiments. For example, even if Embodiments 1 and 2 are described independently in this specification, unless the context clearly indicates otherwise, the effects resulting from the organic combination of Embodiments 1 and 2 may also be included in the effects of the present invention.

[0037] The numerical range indicated by the term "to" in this specification refers to a numerical range that includes the values ​​described before and after the term as the lower limit and the upper limit, respectively. When multiple numerical values ​​are disclosed as the upper and lower limits of an arbitrary numerical range, the numerical range disclosed in this specification can be understood as any numerical range that has any one of the multiple lower limit values ​​and any one of the multiple upper limit values ​​as the lower limit and the upper limit, respectively. For example, when a to b, or c to d is described in the specification, it can be understood that a or more and b or less, a or more and d or less, c or more and d or less, or c or more and b or less is described.

[0038] As used herein, terms such as "about" or "substantially" mean a reasonable amount of variation from the term that does not significantly alter the final result. These terms may be interpreted to include a variation of at least ±5% or at least ±10%, provided that such variation does not alter the meaning of the term and render it invalid.

[0039] In this specification, the term "layer" may include cases where the film is formed not only over the entire area when observing the area where the film exists, but also cases where the film is formed over only a portion of the area. For example, the surface of the layer or film may be defined to include a flat shape, a non-flat shape, and a combination thereof; or a continuous shape, a discontinuous shape, and a combination thereof. For example, when another member is formed of a film directly on top of one member, the coverage of the other member on the surface of the one member may be defined as 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 99% or more.

[0040] In this specification, the particle diameter may mean the average diameter of each particle observed on a cross-section of a substrate using an electron backscatter diffraction (EBSD) device.

[0041] In this specification, the XRD (X-ray diffraction) analysis method is an analysis method that diffracts X-rays onto a specimen to graphically display the internal information of the specimen. It is an analysis method that can confirm which phase is composed of the specimen by showing peaks at unique angles of various phases. Specifically, the results of the XRD analysis method can be displayed as a graph in which the x-axis is 2θ and the y-axis is intensity.

[0042] According to one aspect of the present invention, a superalloy is provided, which is composed of a hard phase and a binder phase, wherein the hard phase includes WC, the binder phase includes Co and a transition metal (however, Co is excluded), and the superalloy has a saturation magnetization of 75 to 85% according to the following formula 1.

[0043] [Formula 1]

[0044] Saturation magnetization rate of cemented carbide (%) = {[M1(emu)] / [M2(emu / g)×M3(g)]}

[0045] In the above equation 1, M1 is the saturation magnetization (emu) of the superalloy, M2 is the theoretical saturation magnetization (emu / g) of Co, and M3 is the content of Co in the superalloy (g).

[0046] According to one aspect of the present invention, by including a transition metal in the bonding phase and satisfying the saturation magnetization of the cemented carbide of 75 to 85% according to the above formula 1, the hardness and toughness of the cemented carbide are simultaneously improved, thereby realizing a cemented carbide with both improved wear resistance and fracture resistance. Specifically, if the saturation magnetization of the cemented carbide in the above formula 1 is below the above numerical range, a problem may arise in that the toughness of the cemented carbide is not sufficiently improved, and if it exceeds the above numerical range, a problem may arise in that the mechanical properties of the cemented carbide are deteriorated, such as the precipitation of free carbon, which causes fracture or thermal cracking during cutting.

[0047] Below, the configuration of the present invention is described in more detail.

[0048] 1. Superhard alloy

[0049] The superhard alloy according to the present invention is composed of a hard phase and a bonding phase.

[0050] Hard prize

[0051] The hard phase according to the present invention may be a phase that provides high hardness and strength to the cemented carbide. Specifically, the content of the hard phase may be 75 to 97 wt%, 77 to 93 wt%, 79 to 92 wt%, 80 to 91 wt%, 81 to 90 wt%, 82 to 90 wt%, 83 to 90 wt%, or 84 to 90 wt% based on the total weight of the cemented carbide. When the content of the hard phase satisfies the numerical range, the wear resistance and fracture resistance of the cemented carbide are balancedly improved, so that the life of the cutting tool can be extended. In some examples, the content of the hard phase based on a cemented carbide sample can be analyzed through an EDS (Energy Dispersive X-ray Spectroscopy) analysis method.

[0052] The hard phase according to the present invention includes WC, which improves the wear resistance of a cemented carbide. Specifically, the WC is a carbide containing an equal amount of tungsten and carbon atoms, and can further improve the wear resistance of a cemented carbide.

[0053] In some embodiments of the present invention, the content of the WC based on the total weight of the hard phase may be 90 wt% or more, 91 wt% or more, 92 wt% or more, 93 wt% or more, 94 wt% or more, 95 wt% or more, 96 wt% or more, 97 wt% or more, 98 wt% or more, 99 wt% or more, or 90 to 100 wt%. According to some embodiments of the present invention, when the content of the WC based on the total weight of the hard phase satisfies the numerical range, the hardness of the cemented carbide is improved, thereby improving the wear resistance, and the toughness of the cemented carbide is improved, thereby improving the fracture resistance, so that the life of the cutting tool can be further extended. In some examples, the content of the WC based on the cemented carbide sample can be analyzed through an EDS analysis method.

[0054] In some embodiments of the present invention, the hard phase may further include at least one carbide, nitride, or carbonitride of one or more metals of Groups 4, 5, and 6 of the periodic table. In some examples, the at least one metal of Groups 4, 5, and 6 of the periodic table may include one or more selected from the group consisting of Zr, Hf, Rf, Ce, Th, V, Nb, Ta, Db, Pr, Pa, Cr, Mo, W, Ti, Sg, Nd, and U. In some examples, the content of at least one carbide, nitride and carbonitride of one or more metals of Groups 4, 5 and 6 of the periodic table may be 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, or 0 to 10 wt% based on the total weight of the hard phase. Specifically, when the content of at least one carbide, nitride and carbonitride of one or more metals of Groups 4, 5 and 6 of the periodic table satisfies the numerical range, the hardness of the cemented carbide is improved, thereby improving wear resistance, and the toughness of the cemented carbide is improved, thereby improving fracture resistance, whereby the life of the cutting tool can be further extended.

[0055] Combined

[0056] The binder phase according to the present invention can improve the wear resistance of the cemented carbide by inducing solid solution strengthening and thereby increasing the hardness of the cemented carbide. Here, solid solution strengthening refers to an effect in which a deformation occurs in the crystal lattice around the solute atoms, which impedes the movement of dislocations, so that the solute atoms form an atmosphere around the dislocations and fix the dislocations. Specifically, the content of the binder phase may be 3 to 25 wt%, 7 to 23 wt%, 8 to 21 wt%, 9 to 20 wt%, 10 to 19 wt%, 10 to 18 wt%, 10 to 17 wt%, or 10 to 16 wt% based on the total weight of the cemented carbide. When the content of the binder phase satisfies the above numerical range, the wear resistance and fracture resistance of the cemented carbide are balancedly improved, so that the life of the cutting tool can be extended. In some examples, the content of the above bonding phase can be analyzed using the EDS analysis method based on a superalloy sample.

[0057] The bonding agent according to the present invention includes Co to improve the toughness and hardness of the superalloy.

[0058] In some embodiments of the present invention, the content of Co based on the total weight of the cemented carbide may be 5 to 15 wt%, 6 to 14 wt%, 7 to 13 wt%, 8 to 12 wt%, 9 to 11 wt%, or 9 to 10 wt%. According to some embodiments of the present invention, since the content of Co based on the total weight of the cemented carbide satisfies the numerical range, the hardness of the cemented carbide is improved, thereby improving wear resistance, and the toughness of the cemented carbide is improved, thereby improving fracture resistance, so that the life of the cutting tool can be further extended. In some examples, the content of Co based on the cemented carbide sample can be analyzed through an EDS analysis method.

[0059] The bonding agent according to the present invention includes a transition metal to enhance the hardness of a superalloy by causing solid solution strengthening. In this case, Co is excluded from the transition metal.

[0060] In some embodiments of the present invention, the content of the transition metal based on the total weight of the cemented carbide may be 0.5 to 3.5 wt%, 0.7 to 3.2 wt%, 0.8 to 3.0 wt%, 0.9 to 2.8 wt%, 1.0 to 2.5 wt%, 1.1 to 2.3 wt%, 1.2 to 2.2 wt%, 1.3 to 2.0 wt%, or 1.4 to 1.5 wt%. According to some embodiments of the present invention, since the content of the transition metal based on the total weight of the cemented carbide satisfies the numerical range, the solid solution strengthening effect sufficiently occurs, so that the hardness of the cemented carbide is sufficiently improved, and the wear resistance can be further improved. Accordingly, the life of the cutting tool can be further extended. In some examples, the content of the transition metal based on the cemented carbide sample can be analyzed through an EDS analysis method.

[0061] In some embodiments of the present invention, the transition metal may include at least one of Ru, Re, Pd, Ir, Rh, Os, and Pt, and specifically may include any one selected from the group consisting of Ru, Re, and combinations thereof. Here, when any one selected from the group consisting of Ru, Re, and combinations thereof is used as the transition metal, the melting point is higher than that of Co compared to other transition metals, so that the heat resistance and strength of the binder phase can be further improved, and thus the fracture resistance of the cemented carbide can be improved, and the carbon content can be increased by lowering the saturation magnetization of the cemented carbide.

[0062]

[0063] Parameters

[0064] The saturation magnetization of the cemented carbide according to the present invention is 75 to 85% according to the following equation 1. Specifically, the saturation magnetization of the cemented carbide may be 76 to 84%, 77 to 83%, 78 to 82%, 79 to 81%, or 80 to 81%. Specifically, if the saturation magnetization of the cemented carbide is below the above numerical range, a problem may arise in that the toughness of the cemented carbide is not sufficiently improved, and if it exceeds the above numerical range, a problem may arise in that the mechanical properties of the cemented carbide deteriorate, such as the precipitation of glassy carbon, which causes defects or thermal cracks during cutting.

[0065] [Formula 1]

[0066] Saturation magnetization rate of cemented carbide (%) = {[M1(emu)] / [M2(emu / g)×M3(g)]}

[0067] In the above equation 1, M1 is the saturation magnetization (emu) of the superalloy, M2 is the theoretical saturation magnetization (emu / g) of Co, and M3 is the content of Co in the superalloy (g).

[0068] That is, the saturation magnetization (%) of the above-mentioned superalloy means the ratio of the saturation magnetization (emu) of the superalloy to the theoretical saturation magnetization (emu) of Co contained in the superalloy. In some examples, the saturation magnetization (emu) of the superalloy can be measured using a known magnetic property measuring device. In addition, the theoretical saturation magnetization of Co can be a known value.

[0069] Meanwhile, in the bonding phase according to the present invention, Co can have crystal phases of a hexagonal close-packed (HCP) structure and a face-centered cubic (FCC) structure. The phase transformation temperature of Co is approximately 420°C, and the HCP structure is stable at temperatures lower than that, and the FCC structure is stable at temperatures higher than that. However, in cemented carbide, the Co phase is small and thin, so the phase transformation tends to be suppressed, and even when cooled from a high-temperature sintering temperature to room temperature, the FCC structure and the HCP structure may coexist. Since FCC-Co is more ductile than HCP-Co, the toughness of the bonding phase is dependent on FCC-Co, and it is known that a high content of HCP-Co in the bonding phase reduces the ability to suppress crack propagation. Therefore, lowering HCP-Co and increasing FCC-Co may be one factor affecting the fracture resistance of cemented carbide.

[0070] In some embodiments of the present invention, the cemented carbide may not have a peak originating from the HCP (002) plane of Co in the diffraction pattern in the section where 2θ is 40 to 50° based on XRD (X-ray diffraction) analysis. The reason why the peak originating from the HCP-Co (002) plane disappears may be because the FCC→HCP phase transformation that may occur during the cooling process is suppressed by the action of carbon. According to some embodiments of the present invention, since the peak originating from the HCP (002) plane of Co does not exist in the diffraction pattern in the section where 2θ is 40 to 50° based on XRD (X-ray diffraction) analysis, the hardness of the cemented carbide is improved, thereby improving wear resistance, and the toughness of the cemented carbide is improved, thereby improving fracture resistance, so that the life of the cutting tool can be further extended.

[0071] In some embodiments of the present invention, based on XRD (X-ray diffraction) analysis, the intensity of the peak originating from the FCC (111) plane of Co may be higher than the intensity of the peak originating from the HCP (010) plane of Co. According to some embodiments of the present invention, the intensity of the peak originating from the FCC (111) plane of Co is higher than the intensity of the peak originating from the HCP (010) plane of Co, thereby improving the hardness of the cemented carbide, thereby improving wear resistance, and improving the toughness of the cemented carbide, thereby improving fracture resistance, and thus the life of the cutting tool may be further extended.

[0072] In some examples, for the above XRD analysis method, an X-ray diffraction instrument (model name: X'pert) from Malvern Panalytical can be used, a detector equipped with Bragg Brentano HD (hereinafter referred to as 'BBHD') and Pixel 3D can be used, copper (Cu) can be used as the XRD electrode material, and a voltage of 45 kV and a wavelength of Cu-Kα of 40 mA can be used. The BBHD can be equipped with a 1 / 2° antiscatter slit and a 1 / 8° divergence, and the detector can be used by attaching a 1 / 2 solar slit. Measurements can be performed for 2θ of 40° to 50° using the θ-2θ method, and analysis can be performed on the sintered surface of a cemented carbide sample in a state where the height and balance of the sample are aligned.

[0073] In some embodiments of the present invention, the cemented carbide may not contain glassy carbon. According to some embodiments of the present invention, since the cemented carbide does not contain glassy carbon, the mechanical properties of the cemented carbide can be sufficiently realized. For example, an optical microscope can be used as equipment to analyze the presence of glassy carbon in the cemented carbide.

[0074]

[0075] 2. Manufacturing method of superalloy

[0076] According to another aspect of the present invention, a method for manufacturing a cemented carbide according to some embodiments comprises: (S1) preparing a mixed powder including WC powder, Co powder, and a transition metal powder (excluding WC powder and Co powder); (S2) filling the mixed powder with a binder into a mold and molding it to manufacture a molded body; and (S3) sintering the molded body to manufacture a cemented carbide; wherein step (S3) comprises: (a) debinding the molded body in an inert gas atmosphere for 6 to 8 hours; (b) heating the debinded molded body to 1,000 to 1,250°C under a vacuum atmosphere and maintaining it at the highest temperature for 4 to 6 hours; (c) heating the body to 1,350 to 1,380°C under a vacuum atmosphere and maintaining it at the highest temperature for 50 to 80 minutes to manufacture a sintered body; And (d) a step of cooling the sintered body from the highest temperature to 40 to 50°C in a vacuum atmosphere to manufacture the superalloy; a method for manufacturing a superalloy is provided.

[0077] Hereinafter, the configuration of the present invention will be described in more detail step by step.

[0078] (S1) A step of preparing a mixed powder including WC powder, Co powder, and transition metal powder;

[0079] A method for manufacturing a superalloy according to the present invention includes the step of (S1) preparing a mixed powder including WC powder, Co powder, and transition metal powder.

[0080] The mixed powder according to the present invention may include WC powder, Co powder, and transition metal powder. Here, the transition metal powder excludes WC powder and Co powder.

[0081] In some embodiments of the present invention, the particle size of the WC powder may be 0.5 to 4.0 μm or 1.0 to 3.1 μm. According to some embodiments of the present invention, when the particle size of the WC powder satisfies the numerical range, the thermal conductivity of the cemented carbide is improved, so that the progression of wear can be suppressed, and the hardness of the cemented carbide can be further improved.

[0082] In some examples, the particle size of the Co powder is not particularly limited and may be specifically 0.5 to 3 μm.

[0083] In some examples, the particle size of the above transition metal powder is not particularly limited and may be specifically 0.5 to 3 μm.

[0084] In some examples, the mixed powder may further include at least one of a carbide powder, a nitride powder, and a carbonitride powder, and one or more of metals of Groups 4, 5, and 6 of the periodic table.

[0085] In some embodiments of the present invention, the carbon content may be 5 to 6 wt%, 5.1 to 5.6 wt%, 5.2 to 5.51 wt%, or 5.43 to 5.51 wt%, based on the total weight of the mixed powder. Specifically, when the carbon content in the mixed powder is controlled, the HCP↔FCC phase transformation of Co that occurs during the sintering and cooling process is affected, so that a cemented carbide having a high FCC-Co content can be manufactured. According to some embodiments of the present invention, since the carbon content satisfies the above numerical range based on the total weight of the mixed powder, the FCC↔HCP phase transformation of Co that may occur during the cooling process is effectively suppressed, and at the same time, the HCP↔FCC phase transformation of Co that occurs during the sintering and cooling process is affected, so that a cemented carbide having a high FCC-Co content can be manufactured. Accordingly, the hardness of the cemented carbide is improved, thereby improving wear resistance, and the toughness of the cemented carbide is improved, thereby improving fracture resistance, so that the life of the cutting tool can be extended. In addition, the carbon content is proportional to the saturation magnetization. Specifically, when the carbon content is low, the hard phase W is dissolved in Co, so that the apparent Co decreases, thereby lowering the saturation magnetization of the cemented carbide, and when the carbon content is high, the solid solution of W decreases, thereby increasing the saturation magnetization. In other words, the carbon content and saturation magnetization of the cemented carbide are proportional, and accordingly, an appropriate range of carbon content may exist in which the η phase and free carbon are not formed.

[0086] (S2) A step of filling the mixed powder with the binder added into the mold and then molding it to manufacture a molded body;

[0087] The method for manufacturing a superalloy according to the present invention includes the step of (S2) filling the mixed powder with the binder added into a mold and then molding it to manufacture a molded body.

[0088] In some examples, the binder may comprise one or more organic binders selected from the group consisting of paraffin, polyethylene glycol, and fatty acids.

[0089] In some examples, the molded body may be formed using a known press forming method. For example, the pressure and temperature conditions of the press forming may be set to conditions typical in the relevant technical field.

[0090] (S3) A step of sintering the above-mentioned molded body to manufacture a superalloy;

[0091] The method for manufacturing a superalloy according to the present invention includes the step of (S3) sintering the molded body to manufacture a superalloy.

[0092] In some examples, the step (S3) may include the step of (a) debinding the molded body in an inert gas atmosphere for 6 to 8 hours. The binder may be removed through the step (a).

[0093] In some examples, the step (S3) may include the step (b) of heating the degreased molded body to 1,000 to 1,250° C. under a vacuum atmosphere and maintaining it at the highest temperature for 4 to 6 hours.

[0094] In some examples, the step (S3) may include the step (c) of heating the body to 1,350 to 1,380° C. in a vacuum atmosphere and maintaining the temperature at the highest temperature for 50 to 80 minutes to produce a sintered body.

[0095] In some examples, the step (S3) may include the step (d) of cooling the sintered body from a maximum temperature to 40 to 50° C. in a vacuum atmosphere to produce the superalloy.

[0096] 3. Cutting tools

[0097] According to another aspect of the present invention, a cutting tool is provided comprising a substrate comprising a cemented carbide according to some embodiments. Specifically, by including the cemented carbide in the substrate, the wear resistance and fracture resistance of the cutting tool are improved, thereby further extending the life of the cutting tool.

[0098] In some embodiments of the present invention, the cutting tool may further include a coating film on the substrate. According to some embodiments of the present invention, the wear resistance of the cutting tool may be improved by further including a coating film on the substrate.

[0099] In some embodiments of the present invention, the thickness of the coating film may be 1 to 7 μm, specifically 2.5 to 4.0 μm. According to some embodiments of the present invention, the wear resistance of the cutting tool may be further improved by satisfying the thickness of the coating film within the above numerical range.

[0100] In some examples, the deposition of the coating film is not particularly limited and may be performed through a physical vapor deposition method such as ion plating or sputtering; or a chemical vapor deposition method.

[0101] In some examples, the coating film may include at least one of TiN, TiAlN, and TiAlMoN without particular limitation.

[0102] In some examples, the coating film is not particularly limited and may be a single layer or a multilayer.

[0103] In some examples, the coating film may cover part or all of the surface of the substrate.

[0104] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, these are merely examples, and the scope of the present invention is not limited by the following contents. In addition, features described in one embodiment may be combined with other embodiments unless specifically stated otherwise.

[0105]

[0106] [Manufacturing Example: Manufacturing of Superalloy]

[0107] Preparation steps for mixed powder:

[0108] WC powder (particle size = 0.5 to 4.0 μm); Co powder (particle size = 0.5 to 3 μm); and Ru powder (particle size = 0.5 to 3 μm), each having a composition as described in Table 1 below, were wet mixed using a stainless steel ball mill and carbide balls to prepare a mixed powder. At this time, the saturation magnetization rate of the cemented carbide alloy in Table 1 below can be varied by controlling the carbon content with respect to the total weight of the mixed powder. In the case of Examples 1 to 3, the carbon content can be controlled at about 5.43 to 5.51 wt%.

[0109] Forming steps:

[0110] After filling the above mixed powder with the binder added into a mold, a known press molding was performed to manufacture a molded body having the shape of an insert type number ENMX0604-ST.

[0111] Sintering stage:

[0112] (a) A step of debinding the above-mentioned molded body in an inert gas atmosphere for 6 to 8 hours; (b) A step of heating the debinded molded body to 1,000 to 1,250°C in a vacuum atmosphere and maintaining it at the highest temperature for 4 to 6 hours; and (c) A step of heating the body to 1,350 to 1,380°C in a vacuum atmosphere and maintaining it at the highest temperature for 50 to 80 minutes were performed to manufacture a sintered body. (d) The sintered body was cooled from the highest temperature to 40 to 50°C in a vacuum atmosphere to manufacture the cemented carbides of Examples 1 to 3 and Comparative Examples 1 to 3, respectively.

[0113]

[0114] [Experimental Example 1: Calculation of Saturation Susceptibility of Superalloy]

[0115] The saturation magnetization rate (%) of the manufactured superalloy is controlled by adjusting the carbon content of the mixed powder, and can be calculated by the following equation 1.

[0116] [Formula 1]

[0117] Saturation magnetization rate of cemented carbide (%) = {[M1(emu)] / [M2(emu / g)×M3(g)]}

[0118] In the above equation 1, M1 is the saturation magnetization (emu) of the superalloy, M2 is the theoretical saturation magnetization (emu / g) of Co, and M3 is the Co content (g) in the superalloy.

[0119] Raw material composition of sample mixed powder (wt%) Saturated susceptibility of cemented carbide (%) WCCoRu Example 1 89.29.41.485 Example 2 89.29.41.480 Example 3 89.29.41.475 Comparative Example 1 89.29.41.470 Comparative Example 2 89.29.41.460 Comparative Example 3 89.29.41.450

[0120]

[0121] [Experimental Example 2: XRD Analysis and Cutting Performance Evaluation of Cemented Carbide]

[0122] XRD analysis:

[0123] XRD (X-ray diffraction) analysis was performed on the cemented carbide according to each of the above Examples 1 to 3 and Comparative Examples 1 to 3. Specifically, for the XRD analysis, an X-ray diffraction device (model name: X'pert) from Malvern Panalytical was used, and a detector equipped with Bragg Brentano HD (hereinafter referred to as 'BBHD') and Pixel 3D was used. Copper (Cu) was used as the XRD electrode material, and a Cu-Kα wavelength of 45 kV and 40 mA was used. The BBHD was equipped with a 1 / 2° antiscatter slit and a 1 / 8° divergence, and a 1 / 2 solar slit was attached to the detector and used. The measurement was performed for 2θ of 40° to 50° using the θ-2θ method, and the analysis was performed on the sintered surface of the cemented carbide sample in a state where the height and balance of the sample were adjusted. As a result, the presence or absence of peaks in XRD analysis is shown in Table 3 below.

[0124] Fig. 1 shows the XRD analysis results for the section where 2θ is 40° to 50° in the cemented carbide according to Comparative Examples 1 and 2 and Example 2. Fig. 2 shows the XRD analysis results for the section where 2θ is 40° to 55° in the cemented carbide according to Example 2 and Comparative Example 2. Fig. 3 is an enlarged view of the XRD analysis results for the section where 2θ is 42° to 45° in the cemented carbide according to Example 2 and Comparative Example 2.

[0125] Evaluation of cutting performance of cemented carbide:

[0126] The wear resistance and fracture resistance of the superalloy according to Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated under the analysis conditions described in Table 2 below, and the results are shown in Table 3 below.

[0127] Analysis conditions: Wear resistance and fracture resistance. Workpiece material: Inconel 718 SCM440 (interrupted). Machining method: Continuous interrupted (25 22Ψ holes are drilled in a 200Ψ workpiece to form interrupted conditions). Cutting speed (m / min or RPM). 40 m / min. 200 RPM. Feed rate (mm / rev). 0.5. 1.0. Depth of cut (mm). 1.5. 0.8. Cutting conditions: Wet. Dry. Performance comparison method: Comparison of cutting distance until wear amount reaches 450 μm. Comparison of cutting time until tool breakage.

[0128]

[0129] Saturation magnetic susceptibility of sample platinum group element cemented carbide (%) Presence of XRD peak Cutting performance HCP-Co (010) FCC-Co (111) HCP-Co (002) Wear resistance (Meter) Fracture resistance (min) Example 1 Ru85 Detected Detected Not detected 3.427 Example 2 Ru80 Detected Detected Not detected 3.726 Example 3 Ru75 Detected Detected Not detected 3.223 Comparative example 1 Ru70 Detected Detected Detected 2.212 Comparative example 2 Ru60 Detected Detected Detected 1.715 Comparative example 3 Ru50 Detected Detected Detected 1.211

[0130]

[0131] Referring to Table 3 and Figures 1 to 3 above, when Comparative Examples 1 to 3 and Examples 1 to 3 are compared with each other in terms of cutting performance of cemented carbide according to the combination relationship of the saturation magnetization rates of the transition metal and the cemented carbide, it can be inferred that when the transition metal is included and the saturation magnetization rate of the cemented carbide satisfies 75 to 85%, both wear resistance and fracture resistance are excellent, thereby improving tool life.

[0132] Referring to Table 3 and Figures 1 to 3 above, when Comparative Examples 1 to 3 are compared with Examples 1 to 3 in terms of cutting performance of cemented carbide depending on the presence or absence of XRD peaks, Examples 1 to 3, unlike Comparative Examples 1 to 3, did not exhibit peaks originating from HCP-Co(002). Accordingly, it can be inferred that both wear resistance and fracture resistance are excellent, thereby improving tool life.

[0133] Referring to Fig. 3, Example 2, unlike Comparative Example 2, showed that the intensity of the peak originating from the FCC (111) plane of Co was higher than the intensity of the peak originating from the HCP (010) plane of Co, based on XRD (X-ray diffraction) analysis.

[0134] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. A superalloy composed of a hard phase and a binder phase. The above hard phase includes WC, The above bonding phase includes Co and a transition metal (except Co), According to the following equation 1, the saturation magnetization rate of the superalloy is 75 to 85%. Superhard alloy: [Formula 1] Saturation magnetization rate of superalloy (%) = {[M1(emu)] / [M2(emu / g)×M3(g)]} In the above equation 1, M1 is the saturation magnetization (emu) of the cemented carbide, M2 is the theoretical saturation magnetization of Co (emu / g), and M3 is the Co content in the cemented carbide (g).

2. In paragraph 1, Based on the total weight of the above superalloy, the content of Co is 5 to 15 wt%. Superhard alloy.

3. In paragraph 1, Based on the total weight of the above superalloy, the content of the transition metal is 0.5 to 3.5 wt%. Superhard alloy.

4. In paragraph 1, The above transition metals are, Containing at least one of Ru, Re, Pd, Ir, Rh, Os and Pt, Superhard alloy.

5. In paragraph 1, Based on XRD (X-ray diffraction) analysis, In the diffraction pattern in the section where 2θ is 40 to 50°, there is no peak originating from the HCP (002) plane of Co. Superhard alloy.

6. In paragraph 1, The above superalloy does not contain glassy carbon. Superhard alloy.

7. A superalloy composed of a hard phase and a binder phase. The above hard phase includes WC, The above bonding phase includes Co and a transition metal (except Co), Based on the XRD (X-ray diffraction) analysis, the intensity of the peak originating from the FCC (111) plane of Co is higher than the intensity of the peak originating from the HCP (010) plane of Co. Superhard alloy.

8. A method for manufacturing a superalloy according to any one of clauses 1 to 7, (S1) A step of preparing a mixed powder including WC powder, Co powder, and transition metal powder (however, WC powder and Co powder are excluded); (S2) a step of filling the mixed powder with the binder added into a mold and then molding it to manufacture a molded body; and (S3) a step of sintering the above-mentioned molded body to manufacture a super-hard alloy; including; The above step (S3) is: (a) a step of debinding the molded body in an inert gas atmosphere for 6 to 8 hours; (b) a step of heating the degreased molded body to 1,000 to 1,250°C under a vacuum atmosphere and maintaining it at the highest temperature for 4 to 6 hours; (c) a step of manufacturing a sintered body by heating to 1,350 to 1,380℃ in a vacuum atmosphere and maintaining the temperature at the highest temperature for 50 to 80 minutes; and (d) a step of manufacturing the superalloy by cooling the sintered body to a maximum temperature of 40 to 50°C under a vacuum atmosphere; including; Method for manufacturing superalloy.

9. A substrate comprising a superalloy according to any one of clauses 1 to 7; Cutting tools.

10. In paragraph 9, Further comprising a coating film as described above; Cutting tools.

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