Die-casting mold parts, die-casting mold, and die-casting method using the same

Abstract

Provided are a die-casting mold component, a die-casting mold, and a die-casting method that can suppress seizure of molten metal. [Solution] The die-casting mold part comprises a base material (11), a first carbide layer (13) formed from carbide and covering a portion of the base material (11), a first tetrahedral amorphous carbon layer (14) formed from tetrahedral amorphous carbon and covering the first carbide layer (13), and a laminated structure portion (15) having a structure in which second carbide layers (151) and second tetrahedral amorphous carbon layers (152) are alternately laminated.

Description

[Technical Field]

[0001] The present invention relates to a die-casting die component, a die-casting die, and a die-casting method using the same. [Background technology]

[0002] An aluminum die-casting mold part has been proposed in which a first layer made of a diamond-like carbon coating containing silicon (Si) and hydrogen (H) is formed on at least a portion of the exposed surface of the substrate, and a second layer made of a metal oxide coating containing magnesium (Mg), silicon (Si) and aluminum (Al) is formed on at least a portion of the DLC outer surface, which is the surface opposite to the exposed surface of the substrate of the first layer, and the atomic ratio of aluminum (Al) to oxygen (O) (Al / O) in the metal oxide coating is 0.04 or more and less than 0.68 (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-162653 Summary of the Invention [Problem to be solved by the invention]

[0004] With regard to aluminum die-casting die components such as those described in Patent Document 1, there is a demand for improving the dimensional accuracy and productivity of die-cast products by reducing the so-called seizure, which occurs when molten metal injected into the aluminum die-casting die reacts with or fuses to the surfaces of the aluminum die-casting die, core pin, etc.

[0005] The present invention has been made in view of the above-mentioned circumstances, and has an object to provide a die-casting die component, a die-casting die, and a die-casting method that can suppress seizure of molten metal. [Means for solving the problem]

[0006] In order to achieve the above object, the die-casting die part according to the present invention comprises: A base material and a first carbide layer formed from a carbide and covering at least a portion of the base material; a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer; a laminated structure portion including at least one pair of a second carbide layer formed from a carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, the laminated structure portion having a structure in which the second carbide layer and the second tetrahedral amorphous carbon layer are alternately laminated, the second carbide layer being on one end side in the lamination direction and the second tetrahedral amorphous carbon layer being on the other end side in the lamination direction, and the first tetrahedral amorphous carbon layer being covered on one end side in the lamination direction; Equipped with.

[0007] The die casting mold according to the present invention from another viewpoint comprises: A mold body; a protective film formed so as to cover a portion of the mold body facing a cavity into which the molten metal is injected, The protective film is a first carbide layer covering the surface of the facing portion; a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer; a laminated structure portion including at least one pair of a second carbide layer formed from a carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, the laminated structure portion having a structure in which the second carbide layer and the second tetrahedral amorphous carbon layer are alternately laminated, the second carbide layer being on one end side in the lamination direction and the second tetrahedral amorphous carbon layer being on the other end side in the lamination direction, and the first tetrahedral amorphous carbon layer being covered on one end side in the lamination direction; It has.

[0008] The die casting method according to the present invention from another viewpoint is as follows: a casting process in which a die-casting mold including a mold body and a protective film formed so as to cover a portion of the mold body facing a cavity into which the molten metal is injected is used to inject the molten metal into the cavity, thereby discharging oxygen from the cavity and creating a pseudo-oxygen-free environment inside the cavity by causing an oxidation reaction between the oxygen in the cavity and the molten metal; a preparation step of opening the cavity of the die-casting mold to create an oxygen-containing environment in the cavity, removing the die-cast product cast in the casting step, and preparing for the next casting step; The protective film is a first carbide layer covering the surface of the facing portion; a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer; a laminated structure portion including at least one pair of a second carbide layer formed from a carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, the laminated structure portion having a structure in which the second carbide layer and the second tetrahedral amorphous carbon layer are alternately laminated, the second carbide layer being on one end side in the lamination direction and the second tetrahedral amorphous carbon layer being on the other end side in the lamination direction, and the first tetrahedral amorphous carbon layer being covered on one end side in the lamination direction; It has. [Effects of the Invention]

[0009] The die-casting die component and die-casting die according to the present invention have excellent release properties, which leads to a reduction in the amount of release agent used and is easy to maintain. This, for example, reduces the time required to stop the die-casting process for maintenance, thereby improving the productivity of die-cast products. Furthermore, the die-casting die component and die-casting die according to the present invention have higher wear resistance and seizure resistance than conventional die-casting dies provided with protective films such as TiAlN, thereby improving the lifespan of the die-casting die component and die-casting die. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a portion of a die-casting die component according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the change over time in the surface temperature of a die-casting mold in the die-casting method according to the embodiment. [Figure 3] FIG. 1 is a diagram showing the relationship between the heat resistance temperature and hardness of materials that are relatively frequently used as protective films for die-casting die components. [Figure 4] 1A shows the results of evaluating the temperature dependence of hardness of a laminated structure film of tetrahedral amorphous carbon (ta-C) and tungsten carbide (WC) in an oxygen-containing environment and an oxygen-free environment, and FIG. 1B shows the results of evaluating the temperature dependence of film thickness of the laminated structure film in an oxygen-containing environment and an oxygen-free environment. [Figure 5] FIG. 10 is a cross-sectional view of a portion of a die-casting die component according to a comparative example. [Figure 6]1A and 1B show the change in surface roughness of a cast product when a die-casting mold according to an embodiment is used, where FIG. 1A shows the change in maximum height roughness, and FIG. 1B shows the change in arithmetic mean roughness. [Figure 7] FIG. 10 is a cross-sectional view of a portion of a die-casting die component according to a modified example of the present invention. [Figure 8] FIG. 10 is a cross-sectional view of a portion of a die-casting die component according to a modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a die-casting die component according to an embodiment of the present invention will be described with reference to the drawings. The die-casting die component according to the embodiment includes a base material, a first carbide layer formed from carbide and covering at least a portion of the base material, and a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer.

[0012] 1, the die-casting die part according to this embodiment includes a base material 11, a base layer 12 covering the surface of the base material 11 on the +Z direction side, a first carbide layer 13 formed of carbide and covering the +Z direction side of the base layer 12, a first tetrahedral amorphous carbon layer 14 formed of tetrahedral amorphous carbon (ta-C) and covering the +Z direction side of the first carbide layer 13, and a laminated structure 15. Here, examples of the base material 11 include a die body and a core pin that form the cavity (hollow portion) of the die-casting die. The material for forming the base material 11 is, for example, an alloy tool steel (SKD61, SKD8, SKT4, etc.) specified in JIS G 4404. When the base material 11 is a mold body, the aforementioned base layer 12, first carbide layer 13, first tetrahedral amorphous carbon layer 14, and laminated structure portion 15 constitute a protective film 16 formed to cover the portion of the base material 11, which is the mold body, facing the cavity portion into which molten metal is injected.

[0013] The underlayer 12 is formed from a material containing one or more metals selected from chromium (Cr), titanium (Ti), tungsten (W), and niobium (Nb) or an alloy thereof as a main component. The first carbide layer 13 is formed from a metal or semiconductor carbide containing at least one element selected from Group 4 elements, Group 5 elements, Group 6 elements, and Group 14 elements other than carbon. The metal carbide is selected from tungsten carbide (WC), silicon carbide (SiC), vanadium carbide (VC), tantalum carbide (TaC), etc. The underlayer 12 is formed on the surface of a base material that has been nitrided. The presence of this underlayer 12 ensures the adhesion of the first carbide layer 13 to the base material 11. The first carbide layer 13 is formed so as to cover the +Z direction side of the underlayer 12, thereby ensuring the adhesion of the first carbide layer 13 to the underlayer 12. The first tetrahedral amorphous carbon layer 14 is formed so as to cover the +Z direction side of the first carbide layer 13.

[0014] The multilayer structure 15 includes at least one pair of a second carbide layer 151 formed from carbide and a second tetrahedral amorphous carbon layer 152 formed from tetrahedral amorphous carbon (ta-C) and covering the +Z direction side of the second carbide layer 151. In the example shown in FIG. 1 , the multilayer structure 15 includes three pairs of a second carbide layer 151 and a second tetrahedral amorphous carbon layer 152. The multilayer structure 15 has a structure in which the second carbide layers 151 and the second tetrahedral amorphous carbon layers 152 are alternately stacked. Here, the second carbide layer 151 is located on one end side in the stacking direction of the multilayer structure 15, i.e., the -Z direction side, and the second tetrahedral amorphous carbon layer 152 is located on the other end side in the stacking direction, i.e., the +Z direction side. The laminated structure 15 covers the +Z direction side of the first tetrahedral amorphous carbon layer 14 on one end side in the lamination direction, that is, on the −Z direction side.

[0015] The second carbide layer 151 is formed of a metal or semiconductor carbide containing at least one element selected from Group 4 elements, Group 5 elements, Group 6 elements, and Group 14 elements other than carbon, similar to the first carbide layer 13. The metal carbide is selected from tungsten carbide (WC), silicon carbide (SiC), vanadium carbide (VC), tantalum carbide (TaC), etc.

[0016] In the laminated structure 15, the second carbide layers 151 and the second tetrahedral amorphous carbon layers 152 are alternately laminated, which alleviates residual stress occurring in these layers, ensures adhesion between them, and suppresses the progression of cracks.

[0017] Next, a die-casting method according to this embodiment will be described. The die-casting method according to this embodiment uses a die-casting mold including the aforementioned mold body and a protective film formed to cover a portion of the mold body facing the cavity into which the molten metal is injected. This die-casting method includes a casting step in which the molten metal is injected into the cavity of the mold body, and a preparation step in which the cavity of the mold body is opened, the die-cast product cast in the casting step is removed, and preparation for the next casting step is performed. In the casting step, oxygen is expelled from the cavity by injecting the molten metal into the cavity of the closed mold, and the molten metal injected into the cavity preferentially reacts with the oxygen present in the cavity, creating a pseudo-anoxic environment. In the preparation step, the cavity is open, creating an oxic environment. The casting step and preparation step are then alternately repeated. In the casting process, a vacuum pump may be provided, and an exhaust means for exhausting gas present in the cavity of the mold body may be connected to the mold body, and the gas present in the cavity of the mold body may be exhausted by the exhaust means. Alternatively, in the casting process, after exhausting the gas present in the cavity, an inert gas may be introduced into the cavity, thereby causing the inert gas to be present in the cavity. Examples of the inert gas include nitrogen gas.

[0018] In the casting of aluminum die-cast products using this die-casting method, the maximum mold surface temperature is controlled below the aluminum molten metal temperature range by appropriately cooling the mold during the casting process, which is considered a pseudo-oxygen-free environment, as shown in Figure 2. The mold surface temperature is then controlled to 500°C or below before moving on to the preparation process, which is an oxic environment. A casting cycle consisting of a preparation process and a casting process is set up so that the maximum mold surface temperature during this pseudo-oxygen-free casting process is 800°C or below, and the maximum mold surface temperature during the preparation process, which is an oxic environment, is 500°C or below. Aluminum die-cast products are continuously produced by repeating this casting cycle. In other words, the surface temperature of the mold body during die-casting is repeatedly and continuously controlled to be below the heat resistance temperature of the protective film during both the preparation and casting processes.

[0019] Figure 3 shows the relationship between heat resistance temperature and hardness for materials that are frequently used as protective films for die-casting mold parts. As shown in Figure 3, TiAlN is commonly used as a protective film material because its heat resistance temperature in an oxygen-containing environment is higher than the temperature of molten aluminum die-casting metal. Furthermore, the heat resistance temperature of tetrahedral amorphous carbon (ta-C) in an oxygen-containing environment is around 500°C. Furthermore, tetrahedral amorphous carbon (ta-C) has a higher hardness and a lower coefficient of friction than TiAlN.

[0020] The inventors evaluated the temperature dependence of hardness and film thickness of a laminated film of tetrahedral amorphous carbon (ta-C) and tungsten carbide (WC) in both oxygen- and oxygen-free environments. The results are shown in Figures 4(A) and 4(B). As shown in Figures 4(A) and 4(B), in an oxygen-containing environment, the laminated film deteriorated and fractured when the ambient temperature exceeded 600°C. In contrast, in an oxygen-free environment, the laminated film did not deteriorate at ambient temperatures between 600°C and 800°C. Therefore, if this laminated film is used as a protective film for the mold body, it is estimated that the protective film will not deteriorate even during the die-casting process, in which the cavity is placed in an oxygen-free environment.

[0021] Therefore, in the aluminum die casting process using the die casting method according to this embodiment, a casting cycle consisting of a preparation step and a casting step is set so that the maximum temperature of the mold surface in the casting step, which is a pseudo-oxygen-free environment, is below the temperature range of the molten metal, and the maximum temperature in the preparation step, which is an aerobic environment, is below a temperature at which the protective film on the mold surface will not deteriorate. Here, just before transitioning to the preparation step, which creates an aerobic environment inside the cavity, the temperature inside the cavity is lowered to a temperature at which the protective film will not deteriorate, and then transitioning to the preparation step, which opens the cavity. This allows the use of a mold body in which the second tetrahedral amorphous carbon layer formed from the aforementioned tetrahedral amorphous carbon (ta-C) is exposed in the cavity.

[0022] As mentioned above, tetrahedral amorphous carbon (ta-C) has a higher hardness and a lower coefficient of friction than TiAlN. Therefore, a die-casting mold having a mold body in which a second tetrahedral amorphous carbon layer is exposed in the cavity according to this embodiment has the advantages of higher wear resistance and improved releasability of die-cast products compared to a die-casting mold in which a layer formed of TiAlN is exposed in the cavity. This also leads to a reduction in the amount of release agent used and improves maintainability. Therefore, for example, the time spent stopping the die-casting process for maintenance can be reduced, thereby improving the productivity of die-cast products.

[0023] By the way, for die casting molds, nitrided materials with excellent heat resistance are used to improve seizure resistance. Titanium aluminum (TiAlN) coated using physical vapor deposition (PVD) technology is commonly used. However, these die-casting dies lack sufficient seizure resistance against the molten metal injected into the die, and further improvements in seizure resistance are needed. Die-casting dies coated with amorphous carbon (aC:H), which has poor chemical compatibility with non-ferrous soft metals such as aluminum, have also been proposed. However, amorphous carbon deteriorates due to oxidation reactions at temperatures above 400°C in an aerobic environment, significantly reducing its wear resistance. Therefore, amorphous carbon-coated die-casting dies are limited in aerobic environments above 450°C, especially because the adhesion between the amorphous carbon film and the die body decreases in aerobic environments above 450°C. For this reason, they have traditionally been considered unsuitable for use in die-casting of magnesium, aluminum, and other metals, which require molten metal temperatures of approximately 700°C.

[0024] In contrast, in this embodiment, by focusing on the fact that the heat resistance temperature of tetrahedral amorphous carbon (ta-C) differs between an oxygen-free environment and an oxygen-containing environment, the temperatures in both the casting process carried out in an oxygen-free environment and the preparation process carried out in an oxygen-containing environment are adjusted so that the maximum temperature is below the heat resistance temperature, thereby making it possible to suppress wear and seizure caused by thermal deterioration of the protective film on the die-casting mold.

[0025] Here, we will explain the transition in surface roughness of a cast product when die casting is performed multiple times using the die casting mold of this embodiment, while comparing it with a die casting mold of a comparative example. The die casting mold of this example had a protective film 16 with the structure shown in Figure 1 formed on the surface of a core pin facing the cavity in the mold body into which molten metal is injected. SKD61 was used as the material for forming the core pin base material 11. Furthermore, the thickness of the portion consisting of the first carbide layer 13, first tetrahedral amorphous carbon layer 14, and laminated structure portion 15 of this example was set to 4 μm.

[0026] A comparative die-casting die was used in which a protective film 9016 having the structure shown in FIG. 5 was formed on the surface of a core pin facing a cavity in the die body into which molten metal is injected. In FIG. 5, the same components as those in the embodiment are denoted by the same reference numerals as in FIG. 1. The surface on the +Z direction side of the base material 11 was nitrided. The protective film 9016 was made of carbide and included a first carbide layer 13 covering the nitrided surface on the +Z direction side of the base material 11, which is the core pin; a first TiAlN layer 9014 made of TiAlN covering the +Z direction side of the first carbide layer 13; and a laminated structure 9015. The laminated structure 9015 had a structure including multiple pairs of a second carbide layer 151 made of carbide and a second TiAlN layer 9152 made of TiAlN covering the +Z direction side of the second carbide layer 151. The laminated structure 9015 has a structure in which second carbide layers 151 and second TiAlN layers 9152 are alternately laminated. Here, the second carbide layer 151 is on the -Z direction side of the laminated structure 9015, and the second TiAlN layer 9152 is on the +Z direction side. The -Z direction side of the laminated structure 9015 covers the +Z direction side of the first TiAlN layer 9014. Here, SKD61 was used as the material for forming the base material 11, which is the core pin, as in the example. Moreover, the thickness of the portion composed of the first carbide layer 13, the first TiAlN layer 9014, and the laminated structure 9015 in the comparative example was set to 8 μm.

[0027] Figures 6(A) and 6(B) show the changes in surface roughness of the core pin portion of the cast product after multiple die-casting cycles using the die-casting dies of the Example and Comparative Example. Aluminum was used for the die-casting. Figure 6(A) shows the maximum height roughness measured according to JIS B 0601, and Figure 6(B) shows the arithmetic mean roughness. As shown in Figures 6(A) and 6(B), the surface roughness of the Comparative Example tended to increase with increasing number of die-casting cycles (number of shots), whereas the surface roughness of the Example remained approximately constant within the range of 20,000 shots or less. This suggests that the die-casting dies of the Example exhibited relatively little adhesion of aluminum to the protective film 16 on the core pin surface compared to the die-casting dies of the Comparative Example, thereby suppressing the increase in surface roughness of the cast product cast using the die-casting dies.

[0028] In this way, the die-casting die according to this embodiment can reduce adhesion of molten metal material to protective film 16 compared to the die-casting die provided with the protective film using TiAlN according to the comparative example, and therefore can suppress an increase in surface roughness of the casting produced using this die-casting die, thereby improving the quality of the casting.

[0029] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments. For example, as shown in Fig. 7, the protective film 2016 may be configured not to include the base layer 12 and the laminated structure 15 that cover the base material 11. That is, the protective film 2016 that covers the base material 11 of the die-casting die component may have a first carbide layer 13 formed from carbide and covering at least a portion of the base material 11, and a first tetrahedral amorphous carbon layer 14 formed from tetrahedral amorphous carbon and covering the first carbide layer.

[0030] In the embodiment, as shown in FIG. 8 , for example, the protective film 3016 may be formed of a material other than tetrahedral amorphous carbon and may further include a sacrificial layer 3017 covering the second tetrahedral amorphous carbon layer at the other end of the multilayer structure 15 in the stacking direction. The sacrificial layer 3017 may be formed of a material that has a relatively low heat resistance temperature and reacts with oxygen present around the protective film 3016, decomposes, and disappears as soon as the temperature of the base material 11 on which the protective film 3016 is formed exceeds a predetermined temperature. Specifically, the sacrificial layer 3017 may be formed of, for example, amorphous carbon (aC) or Si-containing amorphous carbon (aC:Si). Note that the protective film 3016 shown in FIG. 8 includes only one sacrificial layer 3017 covering the +Z direction side of the multilayer structure 15. However, the protective film may have a structure in which, for example, multiple sacrificial layers made of different materials are stacked on the +Z direction side of the multilayer structure 15.

[0031] In the embodiment, at least one of the first carbide layer 13 and the second carbide layer 151 may be formed from a carbide containing at least one of nitrogen (N) and boron (B) and at least one element selected from Group 4 elements, Group 5 elements, Group 6 elements, Group 13 elements, and Group 14 elements other than carbon. Specifically, at least one of the first carbide layer 13 and the second carbide layer 151 may be formed from TiCN or CrCN.

[0032] In an embodiment, the underlayer 12 may be formed from a compound containing at least one of nitrogen (N) and boron (B) and at least one element selected from Group 4, Group 5, and Group 6 elements. Specifically, the underlayer 12 may be formed from TiCN or CrCN. In an embodiment, a plurality of underlayers formed from different compounds containing at least one of nitrogen (N) and boron (B) and at least one element selected from Group 4, Group 5, and Group 6 elements may be stacked and interposed between the base material 11 and the first carbide layer 13.

[0033] In the embodiment, an example has been described in which the material forming the base material 11 is alloy tool steel, but the material forming the base material 11 is not limited to this and may be, for example, general structural rolled steel (SS330, SS400, SS490, SS540) specified in JIS G3101.

[0034] Although the embodiment has been described as an aluminum die-casting method, the die-casting method according to the present invention is not limited to this and can be applied to die-cast products containing at least one selected from aluminum, zinc, and magnesium. In this case, in the die-casting method, the molten metal injected into the cavity of the mold body may contain at least one selected from aluminum, zinc, and magnesium.

[0035] Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to these. The present invention includes any combination of the embodiments and modifications, and any combination to which appropriate modifications have been made. [Industrial Applicability]

[0036] The present invention is widely applicable as a protective film for die-casting mold parts. [Explanation of symbols]

[0037] 11: base material, 12: underlayer, 13: first carbide layer, 14: first tetrahedral amorphous carbon layer, 15: laminated structure, 16, 2016, 3016: protective film, 151: second carbide layer, 152: second tetrahedral amorphous carbon layer, 3017: sacrificial layer

Claims

1. A base material and a first carbide layer formed from a carbide and covering at least a portion of the base material; a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer; a laminated structure portion including at least one pair of a second carbide layer formed from a carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, the laminated structure portion having a structure in which the second carbide layer and the second tetrahedral amorphous carbon layer are alternately laminated, the laminated structure portion having the second carbide layer at one end in the lamination direction and the second tetrahedral amorphous carbon layer at the other end in the lamination direction, the laminated structure portion covering the first tetrahedral amorphous carbon layer at one end in the lamination direction, Die-casting mold parts.

2. a sacrificial layer formed from a material different from tetrahedral amorphous carbon and covering the second tetrahedral amorphous carbon layer on the other end side in the stacking direction of the stacked structure; The die-casting die component according to claim 1 .

3. the first carbide layer is formed from a carbide of a metal or semiconductor containing at least one element selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, and Group 14 elements other than carbon; The die-casting die component according to claim 1 or 2.

4. the first carbide layer is formed from a carbide containing at least one of nitrogen (N) and boron (B) and at least one element selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Group 13 elements, and Group 14 elements other than carbon; The die-casting die component according to claim 1 or 2.

5. The substrate further includes an underlayer interposed between the base material and the first carbide layer, the underlayer being formed from a material containing, as a main component, one or more metals selected from chromium (Cr), titanium (Ti), tungsten (W), and niobium (Nb) or an alloy thereof. The die-casting die component according to claim 1 or 2.

6. The semiconductor device further includes at least one underlayer interposed between the base material and the first carbide layer, the underlayer containing at least one of nitrogen (N) and boron (B) and at least one element selected from the group consisting of elements of Group 4, Group 5, and Group 6. The die-casting die component according to claim 1 or 2.

7. At least a portion of the base material covered with the first carbide layer is subjected to nitriding treatment. The die-casting die component according to claim 1 or 2.

8. The base material is formed from a general structural rolled steel material specified in JIS G3101. The die-casting die component according to claim 1 or 2.

9. A mold body; a protective film formed so as to cover a portion of the mold body facing a cavity into which the molten metal is injected, The protective film is a first carbide layer covering a surface of the facing portion; a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer; a laminated structure portion including at least one pair of a second carbide layer formed from a carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, the laminated structure portion having a structure in which the second carbide layer and the second tetrahedral amorphous carbon layer are alternately laminated, the laminated structure portion having one end in the lamination direction as the second carbide layer and the other end in the lamination direction as the second tetrahedral amorphous carbon layer, the one end in the lamination direction covering the first tetrahedral amorphous carbon layer, Die casting mold.

10. The molten metal contains at least one selected from aluminum, zinc, and magnesium. The die casting mold according to claim 9.

11. a casting process in which a die-casting mold including a mold body and a protective film formed so as to cover a portion of the mold body facing a cavity into which the molten metal is injected is used to inject the molten metal into the cavity, thereby discharging oxygen from the cavity and creating a pseudo-oxygen-free environment inside the cavity by causing an oxidation reaction between the oxygen in the cavity and the molten metal; a preparation step of opening the cavity of the die-casting mold to create an oxygen-containing environment in the cavity, removing the die-cast product cast in the casting step, and preparing for the next casting step; The protective film is a first carbide layer covering a surface of the facing portion; a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer; a laminated structure portion including at least one pair of a second carbide layer formed from a carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, the laminated structure portion having a structure in which the second carbide layer and the second tetrahedral amorphous carbon layer are alternately laminated, the laminated structure portion having one end in the lamination direction as the second carbide layer and the other end in the lamination direction as the second tetrahedral amorphous carbon layer, the one end in the lamination direction covering the first tetrahedral amorphous carbon layer, Die-casting method.

12. In the casting step, the surface temperature of the protective film is 800°C or less, In the preparation step, the surface temperature of the protective film is 500° C. or less. The die casting method according to claim 11.

13. In the casting process, gas present in the cavity is evacuated. The die-casting method according to claim 11 or 12.

14. In the casting step, after exhausting the gas present in the cavity, an inert gas is introduced into the cavity to create a state in which the inert gas is present in the cavity, and then the molten metal is injected into the cavity. The die-casting method according to claim 11 or 12.

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