WO2009104273A1

WO2009104273A1 - Iron base alloy product with composite coating

Info

Publication number: WO2009104273A1
Application number: PCT/JP2008/053063
Authority: WO
Inventors: 井原仁史; 佐藤嘉高; 渡部清彦; 丹羽司
Original assignee: ユケン工業株式会社
Priority date: 2008-02-22
Filing date: 2008-02-22
Publication date: 2009-08-27

Abstract

An iron base alloy product, such as a metal mold for plastic forming, having a vanadium (V) composite coating superimposed on a surface of chromium-containing iron base alloy substratum (12). The composite coating is composed of, sequentially superimposed from the substratum side, TiN film (14), TiVCN film (16) and VC film (18). The composite coating is formed by first setting an iron base alloy substratum in a chamber of ion plating apparatus and carrying out regulation retention of injected gas rate/gas ratio in correspondence to film species while using titanium and/or vanadium as an evaporation source and using nitrogen gas and/or hydrocarbon gas an injected gas to thereby attain reaction film forming for each of individual layers. This iron base alloy product is low in the surface roughness of iron base alloy substratum (metal mold main body) after removal of the composite coating by a metal dissolving liquid, thereby allowing formation of a new composite coating nearly without grinding and lapping operations.

Description

Iron-base alloy products with composite coating

The present invention relates to an iron-based alloy product provided with a composite coating. For example, in an iron-based alloy product such as a press mold, the composite coating is removed after use over time, and a composite coating is formed again by new ion plating (hereinafter referred to as “IP”). This invention relates to an iron-based alloy product suitable for the above.

Here, a metal plastic working die (press die) will be described as an example of an iron-based alloy product. However, the present invention is not limited to this and is applicable to other cutting tools and resin molding dies. Is possible.

Conventionally, metal plastic working molds such as press molds are generally made of an iron-based alloy (steel), so that it is necessary to perform a composite coating treatment in order to maintain durability such as wear resistance. .

One of the composite coating processes is vanadium carbide (VC) film processing.

The main method for forming a VC film is a thermal reaction precipitation diffusion method (TRD method: Thermal Reactive Deposition and Diffusion) (see Patent Documents 1, 2, and 3).

However, in the case of the TRD method, it is necessary to set the bath temperature to 800 to 1200 ° C. (see the above publication), which is not desirable from the viewpoint of working environment, energy saving, productivity, and the like. That is, the working environment became high temperature, energy for maintaining the bath temperature was required, and it took time to cool the product after coating.

Also, in the case of a mold whose base material (base material) is steel, it is much higher than the tempering temperature of steel (usually 500 to 650 ° C: “Semiconductor / Metal Material Glossary of Terms” Industrial Research Committee, 1999, p1251). The base material is exposed to temperature. For this reason, the TRD method is not suitable for steel products that require high dimensional accuracy, such as metal plastic working dies (pressing, forging, etc.).

Therefore, the applicant of the present application proposed a method for forming a vanadium-based film (composite film) having the following configuration, and obtained a patent having the following configuration (Patent Document 4).

“In the method of reactively forming a vanadium-based coating on the surface of an inorganic substrate by IP,
The vanadium-based coating is a composite coating composed of a VN film, a VCN film, and a VC film sequentially arranged from the substrate side,
Each layer of the vanadium-based coating is formed by reaction by using vanadium as an evaporation source and adjusting and maintaining the injection gas amount and gas ratio corresponding to the film type using nitrogen gas and / or hydrocarbon gas as the injection gas. A method for forming a vanadium-based film characterized by the above. "
Even in a press die that has been subjected to a composite coating treatment by the above method, the composite coating (vanadium-based coating) is worn out after a long period of use (for example, the number of presses of 100,000 to 150,000), and a predetermined molded product ( It is difficult to ensure the processing accuracy of plastic processed products.

In such a case, instead of discarding the mold, it has recently been attempted to reuse it as a recycled product from the viewpoint of saving resources and energy.
Japanese Patent Laid-Open No. 49-118637 Japanese Patent Publication No.54-7610 Japanese Examined Patent Publication 56-18670 Japanese Patent No. 3909658

As described above, when a new hard composite coating is to be formed for recycling a used mold, a new composite coating must be formed without removing the old composite coating on the mold surface (molding surface). I can't.

As a method for removing the composite coating, it is usually considered that the composite coating is dissolved and removed using a solution for the constituent metal of the composite coating.

However, it was found that when the dissolution was removed, the surface roughness increased (fluttered surface), and the composite coating treatment could not be performed as it was. The reason for the large surface roughness is that innumerable micro craters (diameter or depth: about 30 to 50 μm) are generated on the mold surface (molded surface) after removal.

That is, even if a composite coating is formed on the mold surface (base material surface) after dissolution and removal, the surface roughness (surface roughness) similar to that of a new product is secured on the composite coating surface due to the influence of the base material surface. I found it difficult. If the surface roughness is large, the frictional resistance during plastic processing increases, and it is difficult to ensure the same performance as that of a new mold in the recycled mold.

In order to reduce the surface roughness (remove minute craters), it is necessary to perform a smoothing process by grinding or lapping. These smoothing processes require a large number of man-hours. Furthermore, if the crater size is large, the machining allowance (polishing depth) becomes close to 100 μm, and the mold surface deviates from the dimensional tolerance.

In view of the above, the present invention has a small surface roughness of the iron-based alloy substrate (mold body) after removing the composite coating with a metal solution, and requires little smoothing such as grinding or lapping. It is an object (problem) to provide an iron-based alloy material capable of forming a new composite film.

As a result of diligent development to solve the above-mentioned problems, the present inventors made the composite coating into the following film configuration, thereby dissolving the hard composite film with a general-purpose (commercially available) titanium-based metal solution. It was found that the surface roughness of the iron-based substrate after dissolution and removal was small, and a new composite film could be formed without substantial grinding or lapping.

The reason why the surface roughness after dissolution and removal increases is because the first ionization potential (Cr: 6.76 eV, V: 6.74 eV) of Cr contained in the iron-based alloy is close (Δ = 0.02 eV). In the melting treatment, it was estimated that CrC was dissolved together with VC / VN, and an iron-based alloy product having the following configuration was conceived.

In an iron-based alloy product comprising a vanadium (V) -based / titanium (Ti) -based hard composite coating on the surface of an iron-based alloy substrate containing chromium carbide,
The hard composite coating includes a TiN film, a TiVCN film, and a VC film sequentially arranged from the substrate side, and the VC film is located on the outermost surface.

With the above configuration, when an iron-based alloy product is applied to a plastic working mold or the like, durability equivalent to that of a conventional hard composite coating composed of a VN film, a VCN film, and a VC film can be obtained. Hardness is increasing in order of TiN: HV2000, TiVCN: HV2500, VC: HV3500, and the film-forming composition is excellent in wear resistance from a composition having good adhesion to an inorganic substrate (usually low hardness). The fact that it can be changed stepwise or continuously to a composition (usually high in hardness) is also considered to contribute.

Film removal is possible using a commercially available (general purpose) solution for Ti, and the surface roughness of the mold surface after film removal is also close to the surface roughness of the untreated product. The reason for this is presumed that the first ionization potential of Ti is 6.82 eV, which is far from that of Cr (6.76 eV) (Δ = 0.06 eV), so CrC is not dissolved in the solution.

Here, even if the composite coating of the present invention contains a vanadium-based coating, the present inventors can dissolve and remove it with a commercially available release agent for titanium-based IP (dissolution solution), as shown in Examples described later, I found out. That is, the speed of dissolving the VC film of the titanium-based IP release agent is slower than that of the Ti-based film, but when a large number of pinholes appear in the second-layer TiVCN film due to slight dissolution of the VC film, The lower layer TiN is dissolved first, and the composite film is peeled and removed in the film state.

Therefore, after the film removal, when the hard composite film is formed, the number of pretreatment steps such as grinding and lapping of the mold surface for reducing the surface roughness can be substantially reduced.

In the above configuration, the outermost layer hardness of the composite coating is usually set to Vickers hardness: HV3000 or more. It is desirable from the standpoint of wear resistance that the outermost layer hardness of the composite coating is Vickers hardness: HV3000 or more, and the hardness is expressed as follows: film thickness ratio: TiN film / TiVCN gradient coating / VC film = 0.5 / 0.5 / 9 to 3/3/4, and a total film thickness of 2 to 50 μm makes it easy to obtain.

Also, the iron-base alloy base material is not particularly limited as long as it is a steel material containing chromium, chromium carbide is generated to some extent. Usually, it is selected from the group of steel materials having a chromium content of 1.0 to 30% by mass, preferably 5.0 to 25% by mass (see Table 1).

When the iron-based alloy product of the present invention is applied to a metal plastic working mold that also requires dimensional accuracy, the effect of the present invention becomes more remarkable.

The iron-based alloy product having each of the above-described structures is formed on the surface of the iron-based alloy base material using V and / or Ti as an evaporation source and nitrogen gas and / or hydrocarbon gas as an injection gas amount / gas ratio. Can be adjusted and maintained in accordance with the film type, whereby each layer of the composite coating can be produced by reaction film formation.

By adjusting the gas injection amount or gas ratio, the composition of the film formation is good from the composition having good adhesion to the iron-based alloy substrate (normally low hardness) to the composition having good wear resistance (normally high hardness). It can be changed stepwise or continuously.

Furthermore, it is desirable to carry out the reactive film formation of the interlayer bonding layers having the respective gradient compositions by changing the injection gas amount and the gas ratio stepwise or continuously during the transition between the reactive film formation processes of the respective layers. This is because the drop (gap) in composition change between the respective layers is reduced, and delamination is less likely to occur when subjected to thermal shock or mechanical shock.

The substrate temperature during film formation is usually adjusted in the range of 400 to 500 ° C.

As described above, the tempering temperature of the tough steel is usually about 500 to 650 ° C. Therefore, when temperature variation is taken into consideration, 500 ° C. or less is desirable. It becomes difficult to get sex. The upper limit of the IP film formation temperature (substrate temperature) is usually 550 ° C.

Model diagram showing an example of a composite coating in the present invention Schematic model diagram showing an example of an IP device used in the present invention

Explanation of symbols

12 Substrate 14 TiN film 16 TiVCN film 18 VC film 20 First interlayer coupling layer 22 Second interlayer coupling layer

Hereinafter, the present invention will be described in detail based on embodiments. In this specification, the chemical formulas TiN, TiVCN, and VC mean vanadium nitride (cubic system), titanium vanadium carbonitride (same), and vanadium carbide (same), respectively.

Also, “HV” means Vickers hardness measured according to JIS Z 2244.

FIG. 1 is a partial cross-sectional view of an iron-based alloy product according to an embodiment of the present invention. Basically, a TiN film 14 and a TiVCN are arranged on the surface of a steel base 12 in order from the base 12 side. This is an iron-based alloy product (for example, a mold for plastic working) provided with a vanadium-based composite coating composed of the film 16 and the VC film 18.

In the above, when the TiN film 14, the TiVCN film 16, and the VC film 18 are arranged in this order from the base material 12 side, the hardness increases in that order as described above, and the base material, particularly a steel base material (usually HV 600 to 900). And the hardness difference can be reduced. Therefore, even if the surface hardness is high, it becomes easy to ensure adhesion with the substrate. As described above, the VC film 18 is HV3500, and it is easy to ensure the surface hardness that is a factor (parameter) for ensuring wear resistance. If further improvement in wear resistance is required, it is desirable to reduce the friction coefficient (dynamic friction coefficient: JIS K 7125), which is another factor of wear resistance. The dynamic friction coefficient (μ) is 0.3 or less, preferably 0.2 or less. As will be described later, the friction coefficient can be easily obtained by increasing the amount of hydrocarbon (carbon source).

In the present embodiment, although not indispensable, first and second interlayer coupling layers 20 and 22 having a gradient composition are further interposed between the layers of the composite coating, that is, between the TiN film 14 / TiVCN film 16 / VC film 18. I'm allowed. That is, the first interlayer coupling layer 20 is a Ti-rich TiVCN graded layer, and the second interlayer coupling layer 22 is a V-rich TiVCN graded layer.

The TiVCN layer to the TiVCN gradient layer are considered to exist mostly in the form of TiVCN compounds, but are also considered to exist somewhat in the form of other polyvalent compounds of TiC, TiN, TiCN, VC, VN and VCN.

The presence of these interlayer bonding layers 20 and 22 further reduces the hardness difference between the respective layers, and as a result, delamination due to mechanical shock or thermal shock hardly occurs, and as a result, the toughness of the vanadium-based coating increases. That is, durability is increased.

More specifically, the film thickness ratio of each film layer is set such that TiN film 14 / TiVCN film 16 / VC film 18 = 0.5 / 0.5 / 9 to 3/3/4, preferably 1/1 / The thickness is 8 to 2.5 / 2.5 / 5, most preferably about 2/2/6, and the total film thickness is 2 to 50 μm, preferably 3 to 12 μm, and most preferably about 10 μm.

If the film thickness ratio of the VC film to the TiN film or the TiVCN film is too large, the compression stress of the film increases when the film thickness of the VC film exceeds 10 μm. Delamination with the TiVCN film is likely to occur. Moreover, since the film toughness is lowered, cracks are likely to occur in the VC film due to impact during forging.

Conversely, if the film thickness ratio of the VC film to the TiN film or TiVCN film is too small, the hardness of the entire coating becomes HV3300 or less, making it difficult to obtain wear resistance.

Also, if the total film thickness of the composite coating is too small, it is difficult to obtain the required surface hardness (abrasion resistance), and conversely if it is too large, delamination of the composite coating from the substrate tends to occur. Further, since the film toughness is lowered, cracks are likely to occur in the coating film due to impact during pressing and forging.

Further, the layer thickness (film thickness) of the interlayer coupling layers 20 and 22 is much thinner than the TiN film, the TiVCN film, and the VC film that are the constituent layers of the vanadium-based film. It is desirable that the layer be as thin as possible if it has an interlayer coupling effect. Usually, it is 0.5 / 10 to 3/10, preferably 1/10 to 2/10, most preferably TiN film or TiVCN film. About 1.5 / 10. The reason for the setting is estimated as follows.

It is considered sufficient to have a three-layer structure in order to suppress peeling due to the hardness difference between the substrate and the coating. Further, even if there is no interlayer bonding layer, the hardness difference between the coating layers is within HV1000, and therefore it is considered that a thickness greater than the above setting is not necessary for the purpose of use.

Here, as the iron-based alloy, a steel material (usually tool steel) having a chromium content of 1.0 to 30% by mass is used. The steel material not containing chromium according to the present invention does not have the problem of solving the problem of the present invention (the mold surface after the removal of the composite film becomes a fluttered surface), and is mechanically similar to a metal plastic working mold. This is because iron-base alloy products that are susceptible to shock and thermal shock are planned.

As the tool steel, Fe-based alloys (tough steel materials) such as high-speed steel, die steel, powdered high-speed steel, and semi-high-speed steel can be suitably used.

Specific examples of the iron-based alloy include those shown in Table 1. In Table 1, the chromium content of each steel material is also shown.

Next, the iron base alloy product (mold for plastic working) of the above embodiment will be described by taking as an example a case where a composite film is formed (film formation) on an iron base alloy substrate made of tool steel. do.

In this embodiment, an IP device as shown in FIG. 2, usually an arc IP (AIP) device, is used. The AIP method uses vanadium as an evaporation source, nitrogen gas and / or hydrocarbon gas as a source gas, and adjusts and maintains the injection gas amount and gas ratio corresponding to the film type, thereby forming a TiN film, a TiVCN film, and a VC film. This is because it is easy to form a reactive film on a substrate with high purity. Naturally, other types of IP methods such as a multi-cathode thermionic irradiation method, a high-frequency excitation method, a holo-cathode discharge method, a cluster method, and an activated reaction deposition method are also possible.

The IP device includes a plurality of (two in the illustrated example) evaporation source holding portions (pot portions) 25 and 25A for holding titanium or vanadium in a chamber 24, and a workpiece (base) connected to a bias voltage source 26. Material) 28 is provided. Furthermore, the chamber 24 includes an exhaust port 32 connected to an exhaust pump that maintains the inside of the chamber at a predetermined degree of vacuum, and a reaction gas introduction port 34 for introducing a reaction gas (nitrogen and / or methane). A heater 36 that maintains the interior at a predetermined temperature and also maintains the substrate (substrate) 28 at a predetermined temperature is provided.

Then, the case of reactive film formation by the AIP method will be described as an example.

As the evaporation source, titanium (Ti) and vanadium (V) are usually used in a purity of tunaine to threeine. In addition, the gas that is the source of nitrogen and carbon, which are elements that react with vanadium, can use nitrogen gas (N ₂ ) for the former and hydrocarbon gases such as methane (CH ₄ ), ethane, ethylene, acetylene for the latter It is. As the hydrocarbon gas, methane, which is difficult to generate soot, is desirable because unreactive gas contaminates the surface of the apparatus and the substrate. And the purity of each is made from three nine to six nine.

The film formation conditions by the AIP method are as shown in Table 2, for example.

Usually, one or both pots holding titanium and vanadium are heated, and one or both of them are dissolved and evaporated simultaneously. Alternatively, titanium is first held in all pots, heated and evaporated to form the first layer (TiN film), the vacuum in the chamber is released, and half of the plurality of pots are replaced, and the second A layer (TiVCN film) and a third layer (VC film) can also be sequentially formed.

The focus points of the above condition items will be described below.

1) Degree of vacuum: If the degree of vacuum is too high (the absolute pressure is low), the amount of reaction gas will be small, the deposition rate will be slowed and productivity will be reduced, and the deposited film will contain excessive metal components. Or the particles are coarse and have many voids. (It is estimated that the generation of crystal nuclei is delayed.)
On the other hand, if the degree of vacuum is too low (the absolute pressure is high), the amount of reaction gas becomes excessive, and the gas that is not used in the reaction and not fully activated acts as an adsorption inhibitor (inhibitor) on the growth film surface. There is a risk.

In particular, when application of the present invention to a mold is expected to improve wear resistance, the surface film (VC film) is required to have slipperiness as well as film hardness. In such a case, it acts as a lubricant. It is desirable to contain C (carbon) in the film. However, when the C content is excessive, the film hardness is lowered and the wear resistance is also lowered. The degree of vacuum that can achieve such a balance is about 10 to 50 mtorr (1.33 to 6.65 Pa), preferably about 20 mtorr (2.66 Pa), and the amount of methane gas is about 400 to 600 mL / min, preferably about 500 mL / min.

2) Arc current: If the current value is too low, the film forming speed is slow, and conversely if it is too high, it is not desirable from the viewpoint of the safety of the apparatus.

3) Bias voltage: Generally, the higher the bias voltage, the slower the film formation speed. Therefore, the bias voltage is set within an appropriate range in consideration of productivity. When the supply gas is nitrogen (N ₂ ), there is almost no influence on the nitride film crystal of the bias voltage, and it can be appropriately set within the range of 50 to 400V, preferably 50 to 200V. In the case of a hydrocarbon such as CH ₄ , if the bias voltage is low, the crystallinity of VC becomes low and it becomes difficult to obtain the wear resistance of the carbide film. Therefore, like nitrogen, it can be in the range of 50 to 400 V, but is preferably about 100 to 200 V, and more preferably about 150 V, from the balance between productivity and crystallinity.

4) Substrate temperature: The higher the temperature, the faster the film formation rate is desirable, but from the standpoint of energy saving and heat resistance of the base material, when the base material is steel, the temperature is below the temperature at which dimensional distortion due to tempering does not occur, usually 350 ~ 550 ° C., preferably 400 to 500 ° C. In the case where the substrate does not generate thermal strain as in the case of ceramics, it may be performed at a maximum IP temperature of about 550 ° C.

Table 3 shows an example of the gas flow rate and the deposition time when an interlayer coupling layer is formed between the layers. In Table 2, X varies depending on the filling amounts and film thicknesses of Ti and V. For example, when the Ti filling amount is about 500 g, the V filling amount is about 700 g, and the total film thickness is 3 to 10 μm, X = 300 to 3000 s.

The amount and pressure of the gas in each interlayer bonding layer in Table 2 do not instantaneously become the amount and pressure, but usually increase continuously to the pressure after an intermediate time of the film formation time, for example, 40 to 50 s, Thereafter, the set value is maintained. The same applies to the TiVCN film and the VC film.

When forming a composite film using steel as a base material, it is generally desirable that the lower hardness is the base material side, and an interlayer coupling layer is formed between each layer.

Therefore, in the film forming method of the present invention, even the TiN film having the lowest hardness has a hardness of HV2000, and preferably a vanadium-based film having a hardness of HV3000 or more is easily formed on a substrate such as steel with good adhesion. it can.

Next, test examples performed on the examples and the conventional example (comparative example) in order to confirm the effect of the present invention will be described.

As the IP device, “AIP4024 type” manufactured by Kobe Steel Co., Ltd. was used. V was filled with 800 g of pure three nine, N ₂ was pure five nine, and CH ₄ was pure three nine.

In addition, as the film forming substrate, a press die made of cold die steel (SKD11: HV650, HRC58.0) was used. In addition, the shape of the mold was a short square column, and before forming the composite coating, a length: 70.200 mm, a width: 55.900 mm, and a height: 42.000 mm were used.

Example: In Table 3, a composite film (TiN film / TiVCN film / VC film) having a total film thickness of about 10 μm was formed on the press surface (molded surface) of the mold as a base material with X = 1200 s.

Conventional example: A composite coating (TiN film / TiVCN film / VC film) having a total film thickness of about 10 μm was formed on the press surface of a mold as a base material under the film forming conditions shown in Table 4.

And the test of the following item was done about each metal mold | die obtained by the above and the conventional example.

(1) Durability evaluation:
About the Example and the prior art example, the number of moldings of the mold life (molding failure due to wear) until a defective product was generated was evaluated using a work material (high-tensile steel plate 590 kg class, 3.6 mmt).

In both the example and the conventional example, 140,000 pieces could be molded, and it was confirmed that the example had the same durability performance as the conventional example.

(2) Surface roughness change accompanying film removal:
For the molds of the examples and conventional examples after the durability evaluation (after 140,000 moldings) in the above (1), using the following film removing solution under the following conditions, after removing the film, the surface roughness Was measured. The surface roughness of the untreated product without the hard treatment film was also measured. For the surface roughness, a 10-point average roughness Rz was determined using a stylus type surface roughness measuring instrument (JIS B 0601-1982).

Example: It was performed under the condition of 30 ° C. × 12 h using a 30 mL / L diluted solution of a commercially available titanium-based IP release agent “Titanic 94B” (trade name of Nippon Surface Treatment Chemical Co., Ltd.).

Conventional example: Vanadium-based IP release agent (acidic aqueous solution) was used for in-house preparation, and the conditions were 30 ° C. × 12 h.

The results were as follows: Conventional example: Rz 1.95 μm, Example: Rz 0.25 μm, Untreated product: Rz 0.2 μm. In the case of the present invention, it was confirmed that there was almost no change in surface roughness (surface roughness).

(3) Dimensional change due to lapping after film removal For each mold after film removal, lapping is performed using a lapping agent (diamond paste) until the surface roughness Rz: 0.2 μm or less. After processing, the dimensions were measured to determine the amount of change. Note that the side surface (width) was not lapped because it was not a press-worked surface.

As a result, in the conventional example, the length was −90 μm and the height was −120 μm, whereas in the example, the length was −1 μmm and the height was −2 μm. That is, in the present invention, it was confirmed that the wrapping amount may be very small.

Claims

In an iron-based alloy product comprising a vanadium (V) -based / titanium (Ti) -based composite coating on the surface of an iron-based alloy substrate containing chromium carbide,
An iron-based alloy product, wherein the composite coating includes a TiN film, a TiVCN film, and a VC film arranged in order from the substrate side, and the VC film is located on the outermost surface.
2. The iron-based alloy product according to claim 1, wherein an interlayer coupling layer having a gradient composition is further interposed between the layers of the composite coating.
The iron-based alloy product according to claim 1, wherein the outermost layer hardness of the composite coating is Vickers hardness: HV3000 or more.
In the composite coating, the film thickness ratio is TiN film / TiVCN film / VC film = 0.5 / 0.5 / 9 to 3/3/4, and the total film thickness is 2 to 50 μm. The iron-base alloy product according to claim 3.
2. The iron-base alloy product according to claim 1, wherein the iron-base alloy base material is a steel material having a chromium content of 1.0 to 30% by mass.
2. The iron-based alloy product according to claim 1, wherein the applied product is a metal plastic working mold.
A method for producing an iron-base alloy product according to claim 1,
On the surface of the iron-based alloy base material, V and / or Ti is used as the evaporation source, and the injected gas is nitrogen gas and / or hydrocarbon gas, and the amount and ratio of the injected gas are adjusted and maintained according to the film type. A method for producing an iron-based alloy product, characterized in that each layer of the composite coating is formed by reactive film formation.
A method for producing an iron-base alloy product according to claim 2,
On the surface of the iron-based alloy base material, V and / or Ti is used as the evaporation source, and the injected gas is nitrogen gas and / or hydrocarbon gas, and the amount and ratio of the injected gas are adjusted and maintained according to the film type. In addition, each layer of the composite coating is formed by reactive film formation,
An iron-based alloy product characterized in that, during the transition between the reactive film forming steps of each layer, an interlayer bonding layer of each gradient composition is formed by reactive film formation by changing the injection gas amount and gas ratio stepwise or continuously. Production method.
The method for producing an iron-based alloy product according to claim 7 or 8, wherein the base material temperature in the reactive film formation is adjusted to a range of 400 to 500 ° C.