Coated die

Abstract

Provided is a coated die comprising a die and a rigid coating film formed on at least some of the outer surface of the die, wherein the rigid coating film includes a nitride, carbonitride, oxide, or oxynitride of metallic elements. With respect to the sum of the metallic elements contained in the rigid coating film, the content of Al is 65 atm.% or higher, the content of Cr is 15 atm.% or higher, and the total content of Al and Cr is 80-100 atm.%. The rigid coating film has a surface roughness Ra of 0.05 μm or less, and the rigid coating film has a face-centered cubic lattice in which the d value attributable to the (111) plane is 2.25-2.45 Å.

Description

Coated mold

[0001] The present invention relates to a coated mold having a mold and a hard coating.

[0002] Dies such as punches used in forging, press working, etc. require not only hardness but also wear resistance to extend the life of the dies. To improve the wear resistance of dies, for example, a hard coating made of a nitride or carbonitride such as AlCr or AlCrSi is coated on the die by physical vapor deposition or chemical vapor deposition, and at the same time, good surface smoothness is imparted to the hard coating.

[0003] For example, Patent Document 1 describes a coated mold for plastic working, characterized in that the surface of the mold substrate is coated with a hard coating made of nitrides of AlxCrySiz. Specifically, Patent Document 1 describes that the coated mold for plastic working described therein has improved wear resistance by forming a hard coating that is as smooth as possible on the working surface of the mold by a sputtering method.

[0004] JP 2010-284710 A

[0005] An object of the present invention is to provide a coated mold having excellent durability.

[0006] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention.

[0007] That is, the coated mold according to the present invention comprises a mold and a hard coating formed on at least a portion of the outer surface of the mold, wherein the hard coating contains a nitride, carbonitride, oxide, or oxynitride of a metal element, wherein, in the total amount of the metal elements contained in the hard coating, the Al content is 65 atomic % or more, the Cr content is 15 atomic % or more, and the total content of Al and Cr is 80 atomic % or more and 100 atomic % or less, the surface roughness Ra of the hard coating is 0.05 μm or less, and the d value resulting from the (111) plane of the face-centered cubic lattice of the hard coating is 2.25 Å or more and 2.45 Å or less.

[0008] FIG. 1 is a schematic plan view illustrating the shape of a punch in an example. FIG. 2 is an enlarged view of portion E in FIG. 1. FIG. 3 is a cross-sectional view illustrating an observation location of a coated punch after a cold forging test in an example. FIG. 4 is a cross-sectional image showing an observation surface at each angle of a coated punch after a cold forging test in Example 1. FIG. 5 is a cross-sectional image showing an observation surface at each angle of a coated punch after a cold forging test in Example 2. FIG. 6 is a cross-sectional image showing an observation surface at each angle of a coated punch after a cold forging test in Example 3. FIG. 7 is a cross-sectional image showing an observation surface at each angle of a coated punch after a cold forging test in Comparative Example 1. FIG. 8 is a cross-sectional image showing an observation surface at each angle of a coated punch after a cold forging test in Comparative Example 2.

[0009] When a hard coating is formed by a sputtering method, as in the method described in Patent Document 1, raw materials of the coating that are not ionized during film formation may reach the surface of the die, which is the substrate. A coated die on which a coating is formed in this way may suffer from poor adhesion between the die and the hard coating. When a coated die with poor adhesion is used under high-load processing conditions, such as cold forging, even if the hard coating has good surface smoothness, durability (i.e., die life) may be compromised. Therefore, coated dies with hard coatings are required to have further improvements in durability.

[0010] As a result of intensive research by the present inventors, it has been found that a coated mold having excellent durability can be obtained when the hard coating has a predetermined composition, a surface roughness Ra of a predetermined value or less, and a d value (i.e., interplanar spacing value) resulting from the (111) plane of a face-centered cubic lattice, in a coated mold having a mold and a hard coating formed on at least a portion of the outer surface of the mold.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0012] 1. Configuration of the Coated Mold First, the configuration of the coated mold in this embodiment will be described. The coated mold has a mold and a hard coating formed on at least a portion of the outer surface of the mold. In this specification, the "outer surface of the mold" refers to the surface portion of the mold that comes into contact with the workpiece when the mold is in use (i.e., the functional portion). In other words, it is sufficient that the hard coating is formed on at least a portion of the functional portion of such a mold. These components will be described in detail below.

[0013] 1-1. Mold The type and shape of the mold are not particularly limited. Examples of the mold include extrusion molds, upsetting molds, punching molds, coining molds, and various press molding molds. The material of the mold is also not particularly limited. Examples of the material include iron-based alloys (e.g., SKD (Steel Kogu Dice) material, SKS (Steel Kogu Special) material, etc.), high-speed tool steels (e.g., HSS (High Speed ​​Steel)), cemented carbide alloys, various ceramics, etc.

[0014] Specifically, the die is not particularly limited, but is preferably a punch for plastically working the workpiece by colliding with the workpiece. The type of punch is not particularly limited, and examples include punches having cross-sectional shapes such as polygonal shapes (e.g., square, hexagonal), elliptical shapes, and gear shapes, as well as punches having a shape corresponding to the inner diameter shape of the forged product. For example, a punch having a hexagonal cross-sectional shape can be used as a punch for forming bolts, nuts, etc. In addition, in this specification, the die may also include, for example, plastic working jigs such as punches and pins, and dies used in combination with punches, punches, pins, etc.

[0015] From the viewpoint of requiring particularly high durability, the die is preferably for cold plastic working. Furthermore, from the viewpoint of being used in a particularly harsh environment, among dies for cold plastic working, the die is preferably a die for cold forging. Specifically, tensile stress and compressive stress are repeatedly applied to a cold forging die in a closed region at a high speed (e.g., 50 shots per minute or more). Therefore, compared to other dies that can be used for various purposes, a cold forging die is required to have high durability against repeated stress. By forming a hard coating described below on such a cold forging die, the durability of the die can be more effectively improved and the die life can be extended.

[0016] 1-2. Hard Coating In this embodiment, the hard coating is formed on at least a portion of the outer surface of the mold by, for example, the method described below. The hard coating has a predetermined composition, a surface roughness Ra of a predetermined value or less, and a predetermined d value resulting from the (111) plane of a face-centered cubic lattice. This will be described in detail below.

[0017] <Hard Coating Composition> The hard coating contains nitrides, carbonitrides, oxides, or oxynitrides of metal elements. Furthermore, of the total amount of metal elements contained in the hard coating, the Al content is 65 atomic % or more, the Cr content is 15 atomic % or more, and the total content of Al and Cr is 80 atomic % or more and 100 atomic % or less. In this specification, the term "metal element" refers to not only metal elements but also any metalloid elements that may be optionally contained.

[0018] In this specification, the total composition of the metal elements contained in the hard coating, such as the Al content and Cr content, refers to the average composition of the metal elements contained in the hard coating. The average composition of the metal elements contained in the hard coating can be measured by analysis using, for example, an energy dispersive X-ray spectrometer (EDS), as will be described in detail in the Examples below.

[0019] (Al and Cr) Nitrides, carbonitrides, oxides, or oxynitrides primarily composed of Al and Cr are film types that offer an excellent balance between wear resistance and heat resistance, and also have excellent adhesion to the mold. In particular, increasing the Al content in the nitrides, carbonitrides, oxides, or oxynitrides facilitates the formation of an oxidation protective film on the surface of the hard coating, thereby suppressing oxidation wear of the coating. At the same time, increasing the Al content refines the structure of the hard coating, thereby increasing the hardness of the coating.

[0020] Specifically, the refinement of the structure of a hard coating means that the number of grain boundaries in the coating increases. Disorders in the atomic arrangement, i.e., defects (point defects, line defects, or planar defects), exist within the coating crystals. When external stress is applied to the hard coating during mold use, these defects migrate, resulting in damage to the coating. Meanwhile, grain boundaries act to stop the migration of defects. Therefore, when the proportion of grain boundaries increases due to refinement of the crystals, the movement of dislocations is suppressed, thereby improving the strength of the hard coating.

[0021] In this way, by increasing the Al content ratio, oxidation wear of the hard coating is suppressed, and friction wear of the coating is suppressed by increasing the hardness of the coating due to the refinement of the hard coating structure, and in addition, the strength of the coating under external stress environments is improved.

[0022] In the hard coating of this embodiment, the Al content of the total amount of metal elements contained in the hard coating is 65 atomic % or more. When the Al content is 65 atomic % or more, the aforementioned effect of adding Al can be fully exerted. When the Al content is 65 atomic % or more, the Al content of the total amount of metal elements contained in the hard coating is preferably 67 atomic % or more, more preferably 68 atomic % or more, and more preferably a value selected from the group consisting of 70 atomic %, 72 atomic %, 74 atomic %, and 75 atomic % or more.

[0023] On the other hand, if the Al content is too high, the hardness of the hard coating may decrease, so the Al content is preferably 80 atomic % or less of the total amount of metal elements contained in the hard coating, more preferably 78 atomic % or less, and even more preferably 77 atomic % or less of the total amount of metal elements contained in the hard coating.

[0024] In the hard coating of this embodiment, the Cr content is 15 atomic % or more of the total amount of metal elements contained in the hard coating. A Cr content of 15 atomic % or more facilitates the formation of a uniform and dense protective oxidation film on the surface of the hard coating formed on the coated mold during use of the coated mold of this embodiment, making it easier to suppress damage to the hard coating. Of the total amount of metal elements contained in the hard coating, the Cr content is preferably 18 atomic % or more, more preferably 20 atomic % or more, and even more preferably equal to or greater than a value selected from the group consisting of 22 atomic %, 23 atomic %, 25 atomic %, and 28 atomic %.

[0025] On the other hand, if the Cr content is too high, it becomes difficult to obtain the aforementioned effect of increasing the Al content, and therefore, of the total amount of metal elements contained in the hard coating, the Cr content is 35 atomic % or less, preferably 34 atomic % or less, more preferably 32 atomic % or less, and even more preferably 30 atomic % or less.

[0026] In the hard coating of this embodiment, the total content of Al and Cr is 80 atomic % or more and 100 atomic % or less of the total amount of metal elements contained in the hard coating. When the total content of Al and Cr is 80 atomic % or more and 100 atomic % or less, excellent durability can be imparted to the coated mold. The total content of Al and Cr is preferably 85 atomic % or more, more preferably 87 atomic % or more, even more preferably a value selected from the group consisting of 90 atomic %, 93 atomic %, 96 atomic %, and 99 atomic % or more, and particularly preferably 100 atomic %.

[0027] The hard coating includes nitrides, carbonitrides, oxides, or oxynitrides of the above-mentioned metal elements. From the viewpoint of providing a film type with superior heat resistance, the hard coating is preferably a nitride of a metal element.

[0028] Specifically, one example of such a hard coating is one made of a nitride of a metal element, in which, of the total amount of metal elements contained in the hard coating, the Al content is 65 atomic % or more and 80 atomic % or less, the Cr content is 20 atomic % or more and 35 atomic % or less, and the total content of Al and Cr is preferably 100 atomic %.

[0029] (Metal Elements Other than Al and Cr) The hard coating may contain metal elements other than Al and Cr to the extent that the durability of the coated mold is not significantly reduced.

[0030] For example, the hard coating may contain one or more metal elements selected from the group consisting of elements from Groups 4a, 5a, and 6a of the periodic table (Groups 4, 5, and 6, respectively, in the long-form periodic table) and Si, B, Y, Yb, and Cu, in order to improve properties such as wear resistance, heat resistance, and durability (hereinafter also referred to as "coating properties"). Of these elements, Si and B are examples of metalloid elements among metal elements. These elements may generally be contained in the hard coating to improve its properties.

[0031] If the content of metal elements other than Al and Cr becomes too high, the durability of the coated member may be reduced. Therefore, when the hard coating contains metal elements other than Al and Cr, the total content of these elements is preferably 20 atomic % or less, more preferably 10 atomic % or less, even more preferably 5 atomic % or less, and particularly preferably 3 atomic % or less, of the total amount of metal elements contained in the hard coating.

[0032] <Surface roughness Ra (arithmetic mean height) of hard coating> In this embodiment, the surface roughness Ra of the hard coating is 0.05 μm or less. In this specification, the "surface roughness Ra of the hard coating" refers to the arithmetic mean height Ra measured using a surface roughness measuring device in accordance with JIS-B-0601 (2001), as will be described in detail in the examples below. More specifically, in this specification, the "surface roughness Ra of the hard coating" refers to the surface roughness Ra of the hard coating after polishing (after post-treatment) when polishing (post-treatment) is performed after the formation of the hard coating, and refers to the surface roughness Ra of the hard coating immediately after the formation of the hard coating when polishing (post-treatment) is not performed after the formation of the hard coating.

[0033] When the surface roughness Ra of the hard coating is 0.05 μm or less, the hard coating has good surface smoothness, and as a result, a coated mold having excellent durability can be obtained. The surface roughness Ra of the hard coating is preferably 0.04 μm or less, and more preferably 0.03 μm or less.

[0034] The surface roughness Ra of the hard coating can be easily reduced to a low value of 0.05 μm or less, for example, by forming the hard coating by an arc ion plating method using a coating device equipped with a permanent magnet, a filter mechanism, etc., as described below, without requiring post-treatment for surface smoothing, such as polishing, after the hard coating is formed. Specifically, by forming the hard coating by such an arc ion plating method, adhesion of macroparticles (droplets) to the mold during coating formation is reduced, resulting in the formation of a hard coating with significantly excellent surface smoothness. As a result, a coated mold with excellent durability can be obtained.

[0035] <d Value Due to the (111) Plane of the Face-Centered Cubic Lattice of the Hard Coating> In this embodiment, the d value due to the (111) plane of the face-centered cubic lattice of the hard coating (hereinafter simply referred to as the "d value of the hard coating") is 2.25 Å (angstroms) or more and 2.45 Å or less. If the d value of the hard coating is less than 2.25 Å, the stress in the coating is too high, making the coating more likely to peel off from the substrate. If the d value of the hard coating is more than 2.45 Å, the coating stress is too low, shortening the coating life. Therefore, it is preferable that the d value of the hard coating be 2.25 Å or more and 2.45 Å or less. As a result, a coated mold with excellent durability can be obtained.

[0036] The d value of the hard coating is preferably 2.30 Å or more, and more preferably 2.35 Å or more. The d value of the hard coating is preferably 2.43 Å or less, more preferably less than 2.40 Å, even more preferably 2.39 Å or less, and particularly preferably 2.38 Å or less.

[0037] In this specification, the "d value resulting from the (111) plane of the face-centered cubic lattice of the hard coating" refers to a value determined by a method that will be described in detail in the Examples below.

[0038] Specifically, the d value attributable to the (111) plane of the face-centered cubic lattice of the hard coating can be determined by identifying the crystal structure of the hard coating using an X-ray analyzer and performing a peak search in the obtained X-ray peak profile. More specifically, the d value attributable to the (111) plane of the face-centered cubic lattice of the hard coating in this specification refers to the d value of the (111) plane of the cubic crystal structure, which is calculated by determining the diffraction angle of the peak attributable to the (111) plane of the face-centered cubic lattice of chromium nitride (CrN) and using Bragg's formula shown in the following formula (1). In the formula (1), d: interplanar spacing, λ: X-ray wavelength (1.5406 Å), and θ: X-ray diffraction angle.

[0039] The d value of the hard coating can be set to 2.25 Å or more and 2.45 Å or less by forming the hard coating by, for example, a common arc ion plating method.

[0040] <Hard Coating Thickness> The hard coating in this embodiment is not particularly limited, but is preferably 4 μm or more. When the hard coating has a thickness of 4 μm or more, the durability of the hard coating against stress can be further improved, and a coated mold with superior durability can be obtained.

[0041] In this specification, the "thickness of the hard coating" means a value calculated by measuring the dimensional change before and after the formation of the hard coating, as will be described in detail in the Examples below.

[0042] The thickness of the hard coating is more preferably 5 μm or more, and even more preferably 6 μm or more. There is no particular upper limit to the thickness of the hard coating, but for example, the thickness of the hard coating is preferably 10 μm or less, and more preferably 8 μm or less.

[0043] As described above, the coated die of this embodiment has excellent durability and can be suitably applied to, for example, punches for cold forging that are used in harsh environments.

[0044] 2. Other Configurations of the Coated Mold In the coated mold of this embodiment, a base layer may be provided between the mold and the hard coating, if necessary, in order to further improve the adhesion between the mold and the hard coating.

[0045] In particular, when the material of the substrate of the mold is an iron-based alloy (e.g., SKD material, SKS material, etc.) or high-speed tool steel (e.g., HSS, etc.), it is preferable to provide a primer layer between the mold and the hard coating, from the viewpoint of reliably suppressing the risk of coating peeling due to the material of the substrate.

[0046] The underlayer may be formed from, for example, a hard coating containing a nitride, carbonitride, oxide, or oxynitride of a metal element that does not satisfy the above-mentioned conditions for a hard coating, or one or more layers of a metal, nitride, carbonitride, or carbide. Furthermore, as long as the durability of the above-mentioned hard coating is not impaired, one or more layers made of the above-mentioned materials may be formed on the hard coating formed on the outer surface of the mold.

[0047] In this embodiment, a hard coating (hereinafter referred to as a "second hard coating") having a different composition and / or physical properties from the first hard coating but satisfying the above-mentioned conditions for a hard coating may be formed on the hard coating (hereinafter referred to as a "first hard coating") formed on the outer surface of the mold. Furthermore, a still further hard coating (hereinafter referred to as a "third hard coating") satisfying the above-mentioned conditions for a hard coating may be formed on the resulting laminate of these coatings.

[0048] Alternatively, the first hard coating and the second hard coating (or the first hard coating, the second hard coating, and the third hard coating) may be laminated together. Furthermore, two or more layers of the first hard coating and the second hard coating (or the first hard coating, the second hard coating, and the third hard coating) may be alternately laminated. Alternatively, as long as the durability of the hard coating is not impaired, one or more layers of a hard coating containing a nitride, carbonitride, oxide, or oxynitride of a metal element, a metal, a nitride, a carbonitride, or a carbide may be sandwiched between the laminated structures of the hard coatings of this embodiment.

[0049] When one or more such underlayers, upper layers and / or different hard coatings are formed, the total thickness of the laminate is preferably 10 μm or less, although there are no particular limitations thereon.

[0050] 3. Manufacturing Method of Coated Mold The coated mold of this embodiment can be manufactured by coating (forming) a hard coating on at least a part of the outer surface of the mold. The hard coating can be formed by sputtering or arc ion plating.

[0051] In sputtering, argon gas is introduced to sputter the target in addition to the reactive nitrogen gas during film formation. Argon gas, an inert gas, does not react with the sputtered metal particles and is not included in the coating. However, ionized argon collides with energy onto the substrate (mold) to which a negative voltage is applied, and some argon may become mixed into the coating. The inclusion of argon in the coating can cause defects in the coating and reduce its strength. Therefore, when a hard coating is formed by sputtering on a mold used under high-load conditions, this can shorten the life of the coated mold.

[0052] Therefore, it is preferable to apply the arc ion plating method to coat the mold with a hard film. In addition, in the arc ion plating method, it is preferable to use a film formation device equipped with a cathode with permanent magnets arranged on the back surface and outer periphery of the target.

[0053] A deposition apparatus used in the arc ion plating method includes, for example, an arc evaporation source including a target that is the material for the hard coating, an anode that receives electrons during arc discharge, an arc power supply for applying an arc current to the target, a furnace (vacuum container) that houses the substrate mold, a substrate rotation mechanism for rotating the substrate in the furnace, a bias power supply for applying a bias voltage to the substrate, a heater for heating the furnace and the substrate, a vacuum pump for creating a vacuum in the furnace, and a gas inlet for introducing an inert gas (helium, neon, argon, krypton) and / or a reactive gas (nitrogen, hydrocarbon, oxygen) into the furnace. The deposition apparatus also preferably includes a filter mechanism that can reduce macroparticles (droplets) that are clumps of the coating material using a magnetic field.

[0054] The film formation method will be described in detail below.

[0055] First, the inside of the furnace is evacuated to a vacuum. At that time, the vacuum pressure is 10 × 10 －３ The vacuum pressure is preferably 5×10 Pa or less. －３Pa or less, and more preferably 1×10 －３ It is more preferable that the pressure is equal to or less than Pa. By drawing a vacuum, it is possible to prevent oxidation of the substrate, which would otherwise occur if heating of the substrate were started in a state where there is a large amount of residual gas in the furnace.

[0056] After evacuation, the substrate is heated to a temperature of preferably 400°C to 550°C, more preferably 420°C to 520°C, and even more preferably 450°C to 500°C. Heating the substrate at a temperature within this range can prevent a decrease in coating adhesion due to insufficient diffusion at the interface between the substrate and the coating caused by an excessively low temperature, and can also prevent the substrate material from being softened by heat.

[0057] The substrate is then etched. This can be accomplished by introducing an inert gas into the furnace, generating a plasma of the inert gas, and bombarding the substrate with inert gas ions, which are applied with a negative bias voltage. Alternatively, the mounted arc evaporation source can be discharged, optionally together with an inert gas, to ionize a metal target attached to the arc evaporation source and the optional inert gas, which are then bombarded with the substrate. When the arc evaporation source is discharged without using an inert gas, etching can be accomplished using only metal ions.

[0058] When etching is performed by converting an inert gas into plasma, the pressure inside the furnace is preferably 0.1 Pa to 5 Pa. If the inert gas pressure is too low, the amount of inert gas ions generated is small, and a sufficient etching effect may not be obtained. On the other hand, if the inert gas pressure is too high, ionized inert gas may collide with non-ionized inert gas, and a sufficient etching effect may not be obtained.

[0059] When etching is performed by ionizing a metal target by discharging an arc evaporation source, the arc current is preferably 50 A to 150 A. If the arc current is too low, it becomes difficult to generate an arc discharge, and sufficient etching may not be possible. On the other hand, if the arc current is too high, a large number of ions are generated, improving the etching effect, but other problems arise. Specifically, if the arc current is too high, many droplets (macroparticles) formed by melting part of the target are generated, and these macroparticles may adhere to the substrate surface, roughening the substrate surface. Such roughness of the substrate (mold) surface affects the surface roughness Ra of the hard coating. Therefore, in order to obtain the desired surface roughness Ra of the hard coating, it is preferable that the arc current is not too high in order to suppress the generation of macroparticles.

[0060] From the viewpoint of both achieving a sufficient etching effect and suppressing the generation of macroparticles, it is preferable that the arc current be set within the aforementioned range of 50 A to 150 A. Furthermore, in order to reduce adhesion of the generated macroparticles to the substrate, it is preferable that the arc evaporation source provided in the film formation apparatus be equipped with a magnetic field filtering mechanism.

[0061] During etching, a negative bias voltage is applied to the substrate. From the viewpoint of obtaining a sufficient etching effect, the applied voltage is preferably −100 V to −1000 V. If the bias voltage applied to the substrate is too low, a sufficient etching effect may not be obtained. On the other hand, if the voltage is too high, abnormal discharge may occur on the substrate surface, potentially damaging the substrate.

[0062] After the etching treatment, a hard coating is formed on the substrate. When forming the coating, a reactive gas is introduced into the furnace. To stabilize the discharge, an inert gas may be mixed with the reactive gas. However, the inert gas may remain in the coating without reacting with the evaporated metal material, which may ultimately cause coating defects. Therefore, when forming a hard coating by mixing a reactive gas and an inert gas, the residual inert gas component in the hard coating is preferably less than 5%, more preferably less than 1%.

[0063] In this specification, the amount of residual inert gas components in the hard coating is the amount measured using an EDS (detector: X-act C3400, analysis software: INCA) manufactured by Oxford Instruments Ltd., which is attached to a scanning electron microscope (S-3400N manufactured by Hitachi High-Tech Fielding Corporation).

[0064] The reactive gas may be selected from nitrogen gas, oxygen gas, methane, or other hydrocarbon gases depending on the application. For example, when forming nitrides of Al and Cr, nitrogen may be introduced into the furnace as the reactive gas.

[0065] In order to form a hard coating containing dense nitrides with excellent strength, the pressure inside the furnace during film formation is preferably 1 Pa to 10 Pa, more preferably 2 Pa to 8 Pa, and even more preferably 4 Pa ​​to 6 Pa. If the pressure is too low, the reaction between the evaporated metal and the reactive gas may be insufficient, making it impossible to form the desired nitride. On the other hand, if the pressure is too high, the evaporated metal ions may collide with the reactive gas, causing these ions to reach the substrate in an energy-depleted state. As a result, these ions may not be able to sufficiently diffuse on the substrate surface, preventing the formation of a dense coating and resulting in a decrease in coating strength.

[0066] It is preferable to gradually increase the absolute value of the negative bias voltage applied to the substrate from the vicinity of the substrate to the vicinity of the surface of the hard coating. For example, it is preferable to gradually increase the absolute value of the negative bias voltage applied to the substrate from the vicinity of the substrate to the vicinity of the surface of the hard coating within the range of −50 V to −200 V. If the bias voltage is too low, soft hexagonal crystal structured AlN (aluminum nitride) may precipitate in the coating, potentially reducing the hardness of the hard coating. On the other hand, if the bias voltage is too high, the energy of metal ions and gas ions attracted by the negative voltage and colliding with the substrate may increase, potentially increasing the effect of striking the coating deposited on the substrate (ion peening effect). As a result, the distortion of the coating may increase, potentially increasing stress. If the stress increases too much, the coating may peel off.

[0067] From the viewpoint of both forming a coating with such high hardness and suppressing peeling on the substrate, the bias voltage during film formation is preferably within the range of −50 V to −200 V described above.

[0068] It is also preferable to gradually increase the arc current applied to the target from the vicinity of the substrate to the vicinity of the surface of the hard coating. For example, it is preferable to gradually increase the arc current applied to the target within a range of 50 A to 200 A from the vicinity of the substrate to the vicinity of the surface of the hard coating.

[0069] As described above, by forming a hard coating by the arc ion plating method using a film-forming apparatus equipped with such a permanent magnet, filter mechanism, etc., a hard coating having excellent surface smoothness can be easily obtained. Furthermore, by varying the absolute value of the negative bias voltage applied to the substrate and the arc current passed through the target as described above, it is possible to control the crystal structure of the hard coating so that it differs between the vicinity of the substrate (near the mold) and the vicinity of the surface. As a result, the crystals of the finally obtained hard coating have a cubic structure with a (111) or (200) plane orientation, and the d-spacing of the (111) plane can be set to 2.25 Å or more and 2.45 Å or less.

[0070] In other words, such an arc ion plating method makes it easier to form a hard coating that satisfies the above-mentioned conditions of the surface roughness Ra of the hard coating and the d value of the (111) plane of the cubic crystal.

[0071] As described above, this specification discloses various aspects of the technology, the main aspects of which are summarized below.

[0072] A coated mold according to a first aspect of the present invention comprises a mold and a hard coating formed on at least a portion of an outer surface of the mold, wherein the hard coating contains a nitride, carbonitride, oxide, or oxynitride of a metal element, wherein, in the total amount of the metal elements contained in the hard coating, the Al content is 65 atomic % or more, the Cr content is 15 atomic % or more, and the total content of Al and Cr is 80 atomic % or more and 100 atomic % or less, the surface roughness Ra of the hard coating is 0.05 μm or less, and the d value resulting from the (111) plane of the face-centered cubic lattice of the hard coating is 2.25 Å or more and 2.45 Å or less.

[0073] A coated mold according to a second aspect of the present invention is the coated mold according to the first aspect, wherein the surface roughness Ra of the hard coating is 0.04 μm or less.

[0074] A coated mold according to a third aspect of the present invention is the coated mold according to the first or second aspect, wherein the hard coating is made of a nitride of a metal element, and the total amount of the metal elements contained in the hard coating is such that the Al content is 65 atomic % or more and 80 atomic % or less, the Cr content is 20 atomic % or more and 35 atomic % or less, and the total content of Al and Cr is 100 atomic %.

[0075] A coated mold according to a fourth aspect of the present invention is the coated mold according to any one of the first to third aspects, wherein the mold is for cold plastic working.

[0076] A coated mold according to a fifth aspect of the present invention is a coated mold according to any one of the first to fourth aspects, wherein the mold is a punch for plastically processing a workpiece by colliding with the workpiece.

[0077] A coated mold according to a sixth aspect of the present invention is the coated mold according to any one of the first to fifth aspects, wherein the mold is made of an iron-based alloy or high-speed tool steel, and has a base layer between the mold and the hard coating.

[0078] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0079] 1. Formation of a Hard Coating on a Punch as a Die In Examples 1 to 3 and Comparative Examples 1 and 2, coated dies for cold forging (hereinafter also referred to as "coated punches") in which a hard coating was formed on a punch as a die were actually manufactured, and various physical properties of the hard coating were measured and calculated, and the durability of the coated punches was evaluated.

[0080] The methods for measuring and calculating various physical properties of the hard coating and the details of the die (punch) used are as follows.

[0081] [Method for measuring the average composition of metal elements contained in a hard coating] Using an Oxford Instruments EDS (detector: X-act C3400, analysis software: INCA) attached to a scanning electron microscope (Hitachi High-Tech Fielding Corporation, S-3400N), the coating portion of the cross section of the Calotest mark was measured under conditions of an acceleration voltage of 15 kV, a live time of 50 s, and repeated four times to calculate the average composition of metal elements contained in the hard coating. The average composition of argon gas contained in the hard coating was also measured in the same manner.

[0082] [Method of Calculating Thickness of Hard Coating] The thickness of the hard coating was calculated by measuring the change in dimension before and after the formation of the hard coating using a micrometer (manufactured by Mitutoyo Corporation).

[0083] [Method for Calculating the d Value of a Hard Coating] The d value of a hard coating was determined by first identifying the crystal structure of the hard coating using an X-ray analyzer ("SmartLab" manufactured by Rigaku Corporation) under the following condition (1). Then, a peak search was performed on the obtained X-ray peak profile under the following condition (2). Specifically, the diffraction angle of the peak due to the (111) plane of the face-centered cubic lattice of chromium nitride (CrN) was determined, and the lattice spacing d value of the (111) plane of the cubic crystal structure was calculated according to the Bragg formula of the above-mentioned formula (1). (1) X-ray diffraction measurement conditions Target: Cu Target output: 40 kV-40 mA 45 kV-200 mA Filter: Kβ filter Incident monochromator: CBO unit (Cu & Co) Counter monochromator: Not used Counter: Scintillation counter Slit: Divergence: 1 mm, Divergence vertical limit: 10 mm, Scattering: Open, Light reception: Open Scanning speed: 1° / min Sampling width: 0.01° Scanning axis: 2θ / θ Measurement angle (2θ): 30° to 46° θ offset: 0° Number of accumulations: 1 (2) Peak search conditions Method: Second-order differential method Peak width threshold: 0.25° Peak intensity threshold: 50 cps

[0084] [Method for Measuring Surface Roughness Ra of Hard Coating (Immediately After Hard Coating Formation or After Polishing (After Post-Treatment))] The surface roughness Ra (arithmetic mean height) of the hard coating was measured using a surface roughness / contour shape combined measuring instrument ("Surfcom NEX" manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with JIS-B-0601 (2001). Specifically, a coated punch was placed on a sample stage, and the surface roughness of the functional portion of the punch substrate on which the hard coating was formed was measured under the following conditions. The surface roughness Ry (maximum height) of the hard coating, as well as the surface roughness Ra and surface roughness Ry of the punch surface before the hard coating was formed, were also measured using the same method. Conditions Measurement type: Roughness measurement Cutoff type: 2RC Tilt correction: Least-squares linear correction Measurement length: 1.3 mm Cutoff wavelength: 0.25 mm Measurement magnification: 10,000x Measurement speed: 0.15 mm / sec

[0085] [Mold] A punch for cold forging and forward extrusion was used as the mold. Specifically, a punch made of cemented carbide conforming to the CIS standard VC30 (CIS019D classification) was used. More specifically, the cemented carbide material was subjected to grinding and cutting to have the following shape, thereby producing a punch for the experiment.

[0086] FIG. 1 is a schematic plan view illustrating the shape of a punch in the example. In FIG. 1, the various reference numerals represent a punch 1, a functional portion 2, a gripping portion 3, and an upper end portion 4. The punch 1 shown in FIG. 1 has a substantially cylindrical shape. As shown in FIG. 1, the punch 1 includes a functional portion 2 that comes into contact with a workpiece during forging, and a gripping portion 3 having a length C for gripping by a forging device. The upper end portion 4 is the leading end surface of the functional portion 2. Specifically, the length L of the functional portion 2 in the longitudinal direction of the punch 1 is 116 mm, and the length C of the gripping portion 3 is 260 mm. More specifically, by performing grinding and cutting, as shown in Fig. 2, which is an enlarged view of part E in Fig. 1, the tip diameter L1 of punch 1 was set to 24.65 mm, the relief diameter (diameter) L2 was set to 24.5 mm, the arc radius of the arc shape formed from tip point P1 was set to 1.5 mm, the relief angle α was set to 1.5°, and the tip angle β of upper end portion 4 was set to 9°. Overall, as shown in Figs. 1 and 2, the tip diameter L1 of punch 1 and the diameter-reduced portion along the longitudinal direction of punch 1 were configured to be connected by a smooth arc shape.

[0087] After grinding and cutting, the outer surface of the functional part 2, including the upper end 4 on which a hard coating will later be formed, was mirror-polished to a surface roughness Ra (arithmetic mean height) of 0.03 μm or less and a surface roughness Ry (maximum height) of 0.3 μm or less.

[0088] Thereafter, hard coatings were formed on the punches thus prepared by different methods to produce coated punches in Example 1 and Comparative Example 1. The manufacturing methods for each coated punch will be described in detail below.

[0089] In Example 1, a coated punch was manufactured by forming a hard coating on a punch using a coating device equipped with a permanent magnet and a filter mechanism. The configuration of the coating device and a specific method for forming the hard coating are described below.

[0090] [Film Formation Apparatus] An arc ion plating type film formation apparatus was used to form (deposit) a hard coating on the substrate surface (in this Example 1, the surface of the functional portion of the punch). The detailed configuration of this film formation apparatus is as follows: The film formation apparatus includes multiple cathodes (arc evaporation sources), a vacuum chamber, and a substrate rotation mechanism. The cathode is equipped with an electromagnetic coil that focuses plasma in front of the target, and a permanent magnet is installed behind the target. The cathode also includes a filter mechanism that can reduce droplets using a magnetic field. The interior of the vacuum chamber can be evacuated using a vacuum pump, and gas can be introduced into the vacuum chamber through a supply port installed in the vacuum chamber. A bias power supply can be connected to the substrates placed in the vacuum chamber, allowing negative bias voltages to be applied independently to the multiple substrates. The substrate rotation mechanism includes a work table, a plate-shaped jig attached to the work table, and a pipe-shaped jig attached to the plate-shaped jig. In the substrate rotation mechanism, the work table rotates at a speed of 1.5 revolutions per minute. The plate-shaped jig and the pipe-shaped jig are each capable of rotating and revolving.

[0091] [Heating and Vacuum Evacuation Process (Pre-Deposition Process)] First, the functional part of the punch as the substrate was fixed to a pipe-shaped jig in the vacuum chamber of the deposition apparatus, and the pre-deposition process was carried out as follows. Specifically, first, the inside of the vacuum chamber was filled with 5 × 10 －３ The chamber was evacuated to a vacuum of less than 100 Pa. Thereafter, the functional part of the punch was heated to a temperature of 500° C. by a heater installed in the vacuum chamber.

[0092] [Ar bombardment process (pre-deposition process)] Then, Ar gas was introduced into the vacuum chamber, and a current was passed through the filament to generate Ar ions. Furthermore, a negative bias voltage was applied to the functional part of the punch to perform Ar bombardment.

[0093] [Film Formation Process] After Ar bombardment, the gas in the vacuum chamber was replaced with nitrogen, and the pressure in the vacuum chamber was adjusted to 4 Pa. Then, power was supplied to the cathode, and a negative bias voltage was applied to the functional portion of the punch (the substrate), forming an approximately 5 μm thick Al and Cr nitride (hard coating). In Example 1, a cathode with an Al content of 75 atomic % and a Cr content of 25 atomic % was used. The bias voltage was gradually increased (graded) from the vicinity of the functional portion of the punch (near the substrate) to the vicinity of the surface of the hard coating within a range of −70 V to −200 V. The arc current was also gradually increased (graded) from the vicinity of the functional portion of the punch (near the substrate) to the vicinity of the surface of the hard coating within a range of 70 A to 180 A.

[0094] For the coated punch of Example 1 produced in this manner, various physical properties of the hard coating after coating formation were measured and calculated by the methods described above.

[0095] Finally, as a preparation for a durability test of the coated punch, the outer surface of the functional portion of the coated punch in Example 1 was again subjected to mirror polishing. After the polishing process, the surface roughness Ra of the functional portion of the coated punch was adjusted to 0.05 μm or less (more specifically, 0.03 μm), and the surface roughness Ry to 0.5 μm or less. The measurement and calculation results of the various physical properties of the hard coating described above, as well as the surface roughness Ra of the hard coating after the polishing process (after post-treatment), are summarized in Table 1 below.

[0096] The durability of the coated punch was evaluated as follows: The evaluation results of the coated punch in Example 1 will be summarized later together with those of other Examples and Comparative Examples.

[0097] [Method for Evaluating Durability of Coated Punch] Durability was evaluated using a coated punch as a cold forging die (for forward extrusion). The cold forging former used and other cold forging test conditions are as follows. Durability was evaluated by observing the exposed base material of the cross section of the coated punch (specifically, the functional part of the coated punch) shown in Figure 3 after use as a cold forging die at each angle. If almost no exposed base material of the coated punch was observed at each angle, the durability of the coated punch was determined to be good. If significant exposed base material of the coated punch was observed at each angle, the durability of the coated punch was determined to be poor. (Conditions for cold forging test) Cold forging former: "BPF-680SSUL" manufactured by Sakamura Machinery Works, Ltd. Die: Carbide punch (coated punch of the example or comparative example) Process: Second process Method: Forward extrusion Processing depth: 110 mm Area reduction rate: 50-65% Rotation speed: 40-50 rpm Forming material: Alloy steel Use: Automotive parts Lubrication: Bonder treatment and forging oil (chlorine-free) Number of pieces processed: 6,000-7,000

[0098] Example 2 In Example 2, a coated punch was manufactured by the same method as in Example 1, except that a cathode having an Al content of 70 atomic % and a Cr content of 30 atomic % was used. As in Example 1, various physical properties of the hard coating of the manufactured coated punch in Example 2 after coating formation were measured and calculated using the methods described above. Furthermore, as in Example 1, the surface roughness Ra and surface roughness Ry of the functional portion of the coated punch in Example 2 were adjusted as a preparation for the durability test. The measurement and calculation results of various physical properties of the hard coating in Example 2, as well as the surface roughness Ra value of the hard coating after polishing (after post-treatment), are summarized in Table 1 below. Thereafter, the durability of the coated punch in Example 2 was evaluated, as in Example 1. The evaluation results of the coated punch in Example 2 will be summarized later, along with those of other Examples and Comparative Examples.

[0099] Example 3 In Example 3, a coated punch was manufactured by the same method as in Example 1, except that a cathode having an Al content of 80 atomic % and a Cr content of 20 atomic % was used. As in Example 1, various physical properties of the hard coating of the manufactured coated punch in Example 3 after coating formation were measured and calculated using the methods described above. Furthermore, as in Example 1, the surface roughness Ra and surface roughness Ry of the functional portion of the coated punch in Example 3 were adjusted as a preparation for the durability test. The measurement and calculation results of various physical properties of the hard coating in Example 3, as well as the surface roughness Ra value of the hard coating after polishing (after post-treatment), are summarized in Table 1 below. Thereafter, the durability of the coated punch in Example 3 was evaluated, as in Example 1. The evaluation results of the coated punch in Example 3 will be summarized later, along with those of other Examples and Comparative Examples.

[0100] Comparative Example 1 In Comparative Example 1, a hard coating was formed using a general arc ion plating coating apparatus (manufactured by Kobe Steel, Ltd.) equipped with a permanent magnet but no filter mechanism, and a coated punch was manufactured in the same manner as in Example 1, except that the negative bias voltage during coating formation was set to a constant value of 60 V and the arc current during coating formation was set to a constant value of 120 A.

[0101] As in Example 1, various physical properties of the hard coating of the coated punch of Comparative Example 1 after coating formation were measured and calculated using the methods described above. Furthermore, as in Example 1, the surface roughness Ra and surface roughness Ry of the functional portion of the coated punch of Comparative Example 1 were adjusted as a preparation for the durability test. However, the surface roughness Ra of the hard coating immediately after formation of the hard coating in Comparative Example 1 was as high as 0.25 μm. Even after the same mirror polishing treatment as in Example 1, the surface roughness Ra of the hard coating after polishing (after post-treatment) exceeded 0.05 μm. The measurement and calculation results of various physical properties of the hard coating in Comparative Example 1, as well as the surface roughness Ra of the hard coating after polishing (after post-treatment), are summarized in Table 1 below. Then, as in Example 1, the durability of the coated punch of Comparative Example 1 was also evaluated. The evaluation results of the coated punch of Comparative Example 1 will be summarized later along with those of the other Examples and Comparative Examples.

[0102] Comparative Example 2: In Comparative Example 2, a coated punch was manufactured by the same method as in Comparative Example 1, except that two cathodes were used: one having an Al content of 62 atomic % and a Cr content of 38 atomic %; and the other having an Al content of 50 atomic % and a Ti content of 50 atomic %. Specifically, in Comparative Example 2, unlike Comparative Example 1, the coating had a three-layer structure: a first layer of AlTiN formed on the surface of the functional portion of the punch as the substrate; a second layer of AlTiN and AlCrN formed on the first layer; and a third layer of AlCrN formed on the second layer. In the first layer, the average composition of the metal elements contained in the hard coating was 50 atomic % Al and 50 atomic % Ti. In the second layer, the average composition of the metal elements contained in the hard coating was 56 atomic % Al, 25 atomic % Ti, and 19 atomic % Cr. In the third layer (hard coating formed on the outer surface of the punch), the average composition of the metal elements contained in the hard coating was 62 atomic % Al and 38 atomic % Cr. The deposition time was adjusted so that the thickness ratio of each layer was 1 (first layer):3 (second layer):1 (third layer).

[0103] As in Example 1, various physical properties of the hard coating after coating formation were measured and calculated using the methods described above for the coated punch manufactured in Comparative Example 2. Furthermore, as in Example 1, the surface roughness Ra and surface roughness Ry of the hard coating formed as the third layer of the functional portion of the coated punch in Comparative Example 2 were adjusted as a preparation for the durability test. However, the surface roughness Ra of the hard coating immediately after formation in Comparative Example 2 was as high as 0.20 μm. Even after the same mirror polishing treatment as in Example 1, the surface roughness Ra of the hard coating (third layer) after polishing (post-treatment) exceeded 0.05 μm. The measured and calculated results of various physical properties of the hard coating in Comparative Example 2, as well as the surface roughness Ra of the hard coating (third layer) after polishing (post-treatment) are summarized in Table 1 below. Then, as in Example 1, the durability of the coated punch in Comparative Example 2 was also evaluated. The evaluation results of the coated punch in Comparative Example 2 will be summarized later along with those of the other Examples and Comparative Examples.

[0104] Table 1 below summarizes the physical properties of the hard coatings of the coated punches of Examples 1 to 3 and Comparative Examples 1 and 2. The hard coatings of the coated punches of Examples 1 to 3 and Comparative Examples 1 and 2 did not contain any residual inert gas (specifically, argon gas). Figure 4 shows cross-sectional images of the observation surface of the coated punch at each angle after the cold forging test in Example 1. Figure 5 shows cross-sectional images of the observation surface of the coated punch at each angle after the cold forging test in Example 2. Figure 6 shows cross-sectional images of the observation surface of the coated punch at each angle after the cold forging test in Example 3. Figure 7 shows cross-sectional images of the observation surface of the coated punch at each angle after the cold forging test in Comparative Example 1. Figure 8 shows cross-sectional images of the observation surface of the coated punch at each angle after the cold forging test in Comparative Example 2.

[0105]

[0106] As shown in Table 1 above, the coated punches in Examples 1 to 3 had low hard coating surface roughness Ra values ​​and good surface smoothness not only after polishing (after post-treatment) but also immediately after hard coating formation. Furthermore, as shown in Figures 4 to 6, the coated punches in Examples 1 to 3 had good durability, with almost no exposure of the base material of the punch being observed at any angle after the cold forging test.

[0107] On the other hand, as shown in Table 1 above, the coated punches in Comparative Examples 1 and 2 had a high surface roughness Ra of more than 0.05 μm even after polishing (after post-treatment), indicating poor surface smoothness. Furthermore, as shown in Figure 7, the coated punch in Comparative Example 1 showed the largest exposed portion of the punch base material of approximately 600 μm at 0° after the cold forging test, indicating poor durability. Furthermore, as shown in Figure 8, the coated punch in Comparative Example 2 also showed the largest exposed portion of the punch base material of approximately 300 μm at 270° after the cold forging test, indicating poor durability.

[0108] 2. Formation of a hard coating on a test piece made of SKD material In Examples 4 and 5, a test piece made of SKD material was used as the substrate instead of a punch, and a hard coating was formed on the test piece to prepare a coated test piece. Furthermore, as a reference evaluation, in Examples 4 and 5, the adhesion between the test piece and the coating was observed.

[0109] (Example 4) In Example 4, coated test specimens were prepared in the same manner as in Example 1 above in 1., except that test specimens made of SKD material, an iron-based alloy, were used as the substrate. Furthermore, similar to Example 1 above in 1., various physical properties of the hard coating after coating formation were measured and calculated for the prepared coated test specimens in Example 4 by the methods described in 1. above. Furthermore, as a reference evaluation, the adhesion between the test specimens and the hard coatings was observed for the prepared coated test specimens.

[0110] Example 5 In Example 5, a coated test piece was prepared using the same method as in Example 4, except that a base layer made of CrN was formed between the test piece and the hard coating made of AlCrN. Specifically, a cathode having a composition with a Cr content of 100 atomic % was used, and a bias voltage of −50 V and an arc current of 150 A were used to form a base layer made of CrN on the surface of the test piece until the coating thickness reached 1 μm. Next, a hard coating made of AlCrN was formed on the base layer made of CrN using a method similar to the film formation method described in Example 1 above. Specifically, a cathode having an Al content of 75 atomic % and a Cr content of 25 atomic % was used to form the hard coating made of AlCrN on the base layer. The bias voltage was varied (graded) within the range of −70 V to −200 V, with the absolute value gradually increasing from the vicinity of the base layer made of CrN to the vicinity of the surface. The arc current was also gradually increased (graded) from the vicinity of the CrN underlayer to the vicinity of the surface within the range of 70 A to 180 A. In this case, the thickness of the AlCrN hard coating was formed to be 5 μm.

[0111] As in Example 4, the various physical properties of the hard coating of the coated test piece of Example 5 prepared in this manner were measured and calculated by the methods described in the above section 1. Furthermore, for the prepared coated test piece, the adhesion between the test piece and the base layer and the hard coating was observed as a reference evaluation.

[0112] Table 2 below shows the physical properties of the hard coatings of the coated test pieces of Examples 4 and 5. Note that the hard coatings of the coated test pieces of Examples 4 and 5 did not contain any residual inert gas (specifically, argon gas) components.

[0113]

[0114] As shown in Table 2 above, the coated test pieces in Examples 4 and 5 also had low surface roughness Ra values ​​of the hard coating immediately after hard coating formation, and had good surface smoothness, even without polishing (post-treatment) after hard coating formation. Furthermore, in the coated test piece in Example 4, slight, partial peeling of the hard coating was observed between the test piece and the hard coating. On the other hand, no such peeling of the hard coating was observed in the coated test piece in Example 5. These results demonstrate that when the substrate material of the mold is made of SKD material, it is preferable to provide a primer layer between the mold and the hard coating in order to reliably prevent the risk of coating peeling.

[0115] This application is based on Japanese Patent Application No. 2023-158820 filed on September 22, 2023 and Japanese Patent Application No. 2024-100601 filed on June 21, 2024, the contents of which are incorporated herein by reference.

[0116] The embodiments and examples disclosed herein should be understood to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0117] According to the embodiment of the present invention, a coated die having excellent durability can be obtained. In particular, the coated die according to the embodiment is preferably applied to a cold forging die from the viewpoint of being used in a particularly severe environment.

Claims

1. A coated mold comprising: a mold; and a hard coating formed on at least a portion of an outer surface of the mold; the hard coating comprises a nitride, carbonitride, oxide or oxynitride of a metal element; in the total amount of the metal elements contained in the hard coating, the Al content is 65 atomic % or more, the Cr content is 15 atomic % or more, and the total content of Al and Cr is 80 atomic % or more and 100 atomic % or less; the hard coating has a surface roughness Ra of 0.05 μm or less; and the d value resulting from the (111) plane of the face-centered cubic lattice of the hard coating is 2.25 Å or more and 2.45 Å or less.

2. The coated mold according to claim 1, wherein the surface roughness Ra of the hard coating is 0.04 μm or less.

3. The coated mold according to claim 1, wherein the hard coating is made of a nitride of a metal element, and in the total amount of the metal elements contained in the hard coating, the Al content is 65 atomic % or more and 80 atomic % or less, the Cr content is 20 atomic % or more and 35 atomic % or less, and the total content of Al and Cr is 100 atomic %.

4. The coated mold according to claim 1, wherein the mold is for cold plastic working.

5. The coated mold according to claim 1, wherein the mold is a punch for plastically processing a workpiece by colliding with the workpiece.

6. The coated mold according to claim 1, wherein the material of the mold is an iron-based alloy or high-speed tool steel, and a base layer is provided between the mold and the hard coating.

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