JPH09225557A - Plastic working die and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a plastic working die whose service life is prolonged without gratly increasing in the treatment time such as extension in the nitriding time and the heating diffusion treatment for a long time after nitriding. SOLUTION: This plastic working die is manufactured so that the hardening and tempering is performed after nitriding a base metal of the die after forming, the thickness of a nitrogen compound layer on the base metal surface is <=10μm, the nitrogen concentration to the depth of at least 0.7mm from the base metal surface is >=0.08wt.%, the hardness to the depth of at least 0.7mm from the base metal surface is >=1.07 times the hardness (Hv) of a core part, a nitrogen diffusion layer containing martensitic structure or martensite + bainite structure having super-saturated nitrogen martensite is formed, and the depth of the nitrogen diffusion layer of the base metal surface is >=0.75mm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to forging, extrusion,
The present invention relates to a plastic working die having a long useful life used for performing plastic working such as upsetting, and is also suitable for manufacturing such a plastic working die having a long useful life. The present invention relates to a method for manufacturing a plastic working die.

[0002]

In the conventional warm or hot forging die, quenching at a temperature T ₈₁ and temperatures T ₈₂ , T shown in FIG.
₈₃ tempering process, then temperature 500 ~
It is often the case that various nitriding treatments at 600 ° C. are performed to improve the warm or hot strength so that the hot or hot forging is performed.

On the other hand, due to changes in forging methods,
Since the heat damage generated in the mold is significant, the nitriding time is extended to cope with this, or as shown in FIG.
The heat damage was reduced by deepening the nitride layer by performing a heat diffusion treatment at 0 ° C. to make the diffusion of nitrogen sufficient.

However, there is a problem that the time required for the nitriding treatment is significantly increased by extending the nitriding treatment time or by performing the heat diffusion treatment after the nitriding treatment to sufficiently diffuse nitrogen. there were.

The present invention has been made in view of the above-mentioned conventional problems, and does not form a solid solution with nitrogen in the martensite structure formed by quenching and tempering as in the prior art, but previously adds nitrogen. By forming a solid solution in the austenite state and then converting it to martensite,
Nitrogen is supersaturated and the structure is densified, and it is possible that it will occur in the mold without significantly increasing the processing time, such as extending the nitriding time or heating and diffusion for a long time after the nitriding. An object of the present invention is to provide a metal mold for plastic working which can sufficiently withstand a certain heat damage and has an increased service life, and a manufacturing method thereof.

[0006]

According to a first aspect of the present invention, there is provided a metal mold for plastic working according to claim 1, wherein the thickness of the nitrogen compound layer on the surface of the base material is 10 μm or less and at least 0 from the surface of the base material. Nitrogen concentration up to a depth of 7 mm: 0.08% by weight or more, hardness from the surface of the base material to a depth of at least 0.7 mm: 1.07 times or more the core hardness (Hv). It is characterized by

In an embodiment of the plastic working die according to the present invention, as described in claim 2,
The thickness of the nitrogen compound layer on the surface of the base material can be 5 μm or less, and, as described in claim 3, the nitrogen concentration from the surface of the base material to at least 0.7 mm depth position. : 0.10% by weight or more, or as described in claim 4, hardness from the surface of the base material to at least 0.7 mm depth position:
It can be 1.10 times or more the core hardness (Hv).

Similarly, in an embodiment of the plastic working die according to the present invention, as described in claim 5,
A nitrogen diffusion layer having supersaturated nitrogen martensite can be formed on the base material surface, and in this case,
As described in claim 6, the nitrogen diffusion layer depth on the surface of the base material can be 0.75 mm or more.

Similarly, in an embodiment of the plastic working die according to the present invention, as described in claim 7,
Base material component is% by weight, C: 0.30 to 0.60%, S
i: 1.20% or less, Mn: 1.00% or less, P: 0.
030% or less, S: 0.030% or less, Cr: 2.0 to
6.0%, the balance being Fe and impurities, and in some cases, as described in claim 8, the base material component further contains W: 0.5 to 6.0%. , M
o: 0.3 to 3.0%, V: 0.3 to 3.0%, Ti:
0.3-3.0%, Nb + Ta: 0.3-3.0%, C
o: One or more of 0.3 to 2.0% can be contained.

And, as described in claim 9,
The plastic working die according to the present invention may be a warm plastic working or hot plastic working die.

According to a tenth aspect of the present invention, there is provided a method for producing a plastic working die, in which a die base material after forming is subjected to a nitriding treatment and then a quenching / tempering treatment. , Thickness of nitrogen compound layer on base material surface: 10 μm or less, nitrogen concentration from base material surface to at least 0.7 mm depth position: 0.08 wt% or more, at least 0.
Hardness up to 7 mm depth: 1.0 of core hardness (Hv)
It is characterized in that a nitrogen diffusion layer including a martensite structure having a supersaturated nitrogen martensite structure or a martensite + bainite structure which is 7 times or more is formed.

In the embodiment of the method for manufacturing a plastic working die according to the present invention, as described in claim 11, the nitrogen compound layer thickness on the surface of the base material is 5 μm or less. And at least 0.7 m from the surface of the base metal as claimed in claim 12.
Nitrogen concentration up to m depth position: 0.10 wt% or more, and as described in claim 13, the hardness from the base metal surface to at least 0.7 mm depth position. S: 1.10 times the core hardness (Hv) or more, and as described in claim 14, the nitrogen diffusion layer depth on the surface of the base material: 0.75 mm or more , Can be done as is.

Similarly, in the embodiment of the method for producing a plastic working die according to the present invention, as described in claim 15, the base material component is C: 0.30 by weight%.
0.60%, Si: 1.20% or less, Mn: 1.00%
Hereinafter, P: 0.030% or less, S: 0.030% or less,
Cr: 2.0 to 6.0%, the balance of Fe and impurities may be applied, and in some cases, as described in claim 16, the base material component further comprises W:
0.5-6.0%, Mo: 0.3-3.0%, V: 0.
3 to 3.0%, Ti: 0.3 to 3.0%, Nb + Ta:
0.3-3.0%, Co: 1 of 0.3-2.0%
It can be applied to species or those containing two or more species.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a method for manufacturing a plastic working die according to the present invention. 2 is performed by performing quenching at a temperature T ₁₁ and then performing tempering at a temperature T ₁₂ , a temperature T ₁₃ ... Two or more times (usually 2 to 3 times) after the nitriding treatment of Thus, the thickness of the nitrogen compound layer on the surface of the base material: 10 μm or less, more preferably 5 μm or less, at least 0.
Nitrogen concentration up to 7 mm depth: 0.08 wt% or more,
More desirably, 0.10% by weight or more, hardness from the base material surface to at least 0.7 mm depth position: core hardness (H
v) 1.07 times or more, more preferably the core hardness (H
v) 1.10 times or more, and a nitrogen diffusion layer containing a martensite structure having supersaturated nitrogen martensite or a martensite + bainite structure is formed.

On the other hand, as shown in FIG.
When the nitriding treatment and, if necessary, the heat diffusion treatment are performed after the tempering, as shown in FIG. 3, a nitride layer including a relatively thick nitrogen compound layer and a nitrogen diffusion layer is formed on the surface of the base material. Nitrogen is a solid solution in the martensite structure.

On the other hand, in the present invention, since martensite transformation is carried out after solid solution of nitrogen in the austenite state in advance, a supersaturated nitrogen martensite structure or martensite + bainite structure is formed and the structure is formed. Is densified, has improved high temperature softening resistance and high temperature toughness, and is hardened and tempered to reduce the nitrogen compound layer that is excellent in wear resistance but inferior in toughness. The life of the mold is further improved. In addition, the diffusion of nitrogen deepens the martensite, further improving the durable life.

[0017]

In the plastic working die according to the present invention, as described in claim 1, the nitrogen compound layer thickness on the surface of the base material is 10 μm or less, and at least 0.7 m from the surface of the base material.
Assuming that the nitrogen concentration up to the depth of m: 0.08% by weight or more, the hardness from the surface of the base material to the depth of at least 0.7 mm: 1.07 times the hardness of the core (Hv) or more. Since the surface has a high nitrogen concentration and a large surface hardness, the metal mold for plastic working has a further improved service life.

And, as described in claim 2,
By making the thickness of the nitrogen compound layer on the surface of the base material: 5 μm or less, the durability life of the plastic working die is improved when the amount of the nitrogen compound layer, which has been conventionally excellent in wear resistance, decreases. Although it was said that it could not be expected, the hardness of the core is 1.0 which has a martensite or martensite + bainite structure in which nitrogen is supersaturated as a solid solution.
By forming the diffusion layer having a size 7 times or more, the service life of the plastic working die is further improved.

Further, as described in claim 3, the nitrogen concentration from the surface of the base material to at least the depth of 0.7 mm is 0.10% by weight or more, whereby the plastic working is performed. The service life of the mold is further improved.

Further, as described in claim 4, hardness from the surface of the base material to a depth position of at least 0.7 mm:
By setting the core hardness (Hv) to 1.10 times or more, the service life of the plastic working die is further improved.

Then, as described in claim 5,
By providing a nitrogen diffusion layer having a supersaturated nitrogen martensite on the surface of the base material, the service life of the working die is further improved even when the surface has a small amount of nitrogen compound layer. 6, the nitrogen diffusion layer depth of the base material surface: 0.75 mm or more,
The improvement of the service life will be more sufficient.

Further, as described in claim 7, the base material component, in% by weight, C: 0.30 to 0.60%, S
i: 1.20% or less, Mn: 1.00% or less, P: 0.
030% or less, S: 0.030% or less, Cr: 2.0 to
6.0%, the balance being Fe and impurities, and in some cases, as described in claim 8, the base material component further contains W: 0.5 to 6.0%, Mo: 0. .3 ~
3.0%, V :: 0.3 to 3.0%, Ti: 0.3 to
3.0%, Nb + Ta: 0.3 to 3.0%, Co: 0.
By including at least one of 3 to 2.0%, a metal mold for plastic working having a more excellent service life can be provided.

In this case, C in the base metal component is an element necessary to secure the strength and toughness of the metal mold for plastic working and is preferably 0.30% or more. Since it lowers the workability, it is desirable to set it to 0.60% or less. Si is a useful element for deoxidizing the steel, strengthening the matrix, improving oxidation resistance, etc. Since it reduces machinability and toughness when contained, it is desirable to set it to 1.20% or less, and Mn is an element useful for deoxidizing and desulfurizing action at the time of steel melting and for improving hardenability If it is contained in a large amount, the machinability deteriorates, so it is desirable to set it to 1.00% or less. P and S are impurity elements, and if contained in a large amount, the toughness and the like deteriorate, so P is 0.030% or less, S Is also preferably 0.030% or less, r improves the hardenability and strength of the mold, impact resistance, so improving the wear resistance of 2.0%
It is desirable to set the content above, but if it is too large, the toughness and workability are deteriorated, so it is desirable to set it to 6.0% or less.

Further, W, Mo, V, Ti, Nb, T
Each of a, Co, etc. is a useful element for forming a carbide and increasing the heat treatment hardness to improve the wear resistance, and if necessary, W is 0.5 to 6.0%, Mo. Is 0.3-
3.0%, V 0.3-3.0%, Ti 0.3-3.
0%, Nb + Ta 0.3-3.0%, Co 0.3-
It is also preferable to contain one or more of these in the range of 2.0%.

Further, as described in claim 9,
By making the plastic working mold according to the present invention a warm plastic working or hot plastic working mold,
It is also suitable as a plastic working die, which has a smaller load than cold plastic working.

Further, according to the method for manufacturing a plastic working die according to the present invention, as described in claim 10, after the molding die base material is subjected to nitriding treatment, quenching / Tempered, nitrogen compound layer thickness on base material: 10μ
m or less, nitrogen concentration from the base material surface to at least 0.7 mm depth position: 0.08 wt% or more, hardness from the base material surface to at least 0.7 mm depth position: core hardness (H
v) is 1.07 times or more, and a nitrogen diffusion layer containing a martensite structure having a supersaturated nitrogen martensite or a martensite + bainite structure is formed, so that the surface has a large nitrogen content, A plastic working die having a high hardness and a further improved service life is manufactured.

According to the eleventh aspect, the nitrogen compound layer thickness on the surface of the base material is 5 μm or less, whereby the service life of the plastic working die is further improved. Will be things.

Further, as described in claim 12,
By setting the nitrogen concentration from the surface of the base material to a depth of at least 0.7 mm: 0.10 wt% or more, the service life of the plastic working die is further improved.

Further, as described in claim 13,
By making the hardness from the surface of the base material to a depth of at least 0.7 mm: 1.10 times or more the hardness (Hv) of the core, the service life of the plastic working die is further improved. It will be what you did.

Further, as described in claim 14, by making the nitrogen diffusion layer depth on the surface of the base material: 0.75 mm or more, the service life of the plastic working die is further improved. Will be enough.

Further, as described in claim 15,
Base material component is% by weight, C: 0.30 to 0.60%, S
i: 1.20% or less, Mn: 1.00% or less, P: 0.
030% or less, S: 0.030% or less, Cr: 2.0 to
6.0%, the balance consisting of Fe and impurities, and in some cases, as described in claim 16, the base material component further contains W: 0.5 to 6.0%, M.
o: 0.3 to 3.0%, V: 0.3 to 3.0%, Ti:
0.3-3.0%, Nb + Ta: 0.3-3.0%, C
o: By applying to one containing one kind or two or more kinds of 0.3 to 2.0%, a plastic working die having a more excellent life is manufactured.

[0032]

Against EXAMPLES mold base material after molding with chemical compositions shown in Examples 1-4 Table 1, as shown in FIG. 4, temperature: 520 ° C., time:
After heating and holding for 25 hours, a gas nitriding treatment by air cooling was performed, and then a nitriding agent was applied to the surface of the base material, and then the temperature was set to 11
After heating and holding at 40 ° C for 20 minutes, oil quenching is performed by immersing in oil, followed by temperature: 560 ° C, time: 120
The tempering was carried out three times, which consisted of air cooling after heating and holding for minutes, temperature: 580 ° C., time: 120 minutes, air cooling after heating and holding, temperature: 580 ° C., time: air cooling after heating and holding for 120 minutes.

Comparative Examples 1 and 2 As shown in FIG. 5, the mold base material having the chemical composition shown in Table 1 was subjected to the molding process, and after the temperature was maintained at 1140 ° C. for 20 minutes, the oil was retained. After soaking in oil and quenching, temperature: 560 ° C, time: 120 minutes after heating and holding air cooling, temperature: 580 ° C, time: 120 minutes after heating and holding air cooling, temperature: 580 ° C, time: heating and holding for 120 minutes After tempering 3 times by post air cooling, temperature: 520 ° C,
Time: After heating and holding for 25 hours, gas nitriding treatment by air cooling was performed.

[0034]

[Table 1]

Evaluation Results 1 When the characteristics of the die base materials heat-treated in Examples 1 to 4 and Comparative Examples 1 and 2 were evaluated, the results are shown in Table 2 and FIG.

[0036]

[Table 2]

As shown in Table 2, all of Examples 1 to 4 satisfy the conditions of the present invention, and are more durable than those of Comparative Examples 1 and 2 which do not satisfy the conditions of the present invention. It was possible to improve the life to 1.15 to 1.25 times.

Example 5 A backward extrusion punch 1 for warm forging having the chemical composition shown in Table 1 and having the shape shown in FIG. 7 (note that in FIG. 7, reference numeral 2 is a die, and reference numeral 3 is an object to be forged). After molding, the gas nitriding treatment shown in FIG.
Quenching-> tempering (three times) was performed to manufacture a test punch of the present invention.

Comparative Example 3 After the backward extrusion punch 1 for warm forging having the chemical composition shown in Table 1 and having the shape shown in FIG. 7 was formed, the same process as shown in FIG. Quenching → tempering (3 times)
→ A conventional product test punch was manufactured by gas nitriding.

Evaluation Results 2 The characteristics of the backward extrusion punches for warm forging manufactured in Example 5 and Comparative Example 3 were evaluated. The results are shown in Table 3 and, in order to evaluate the service life, FIG. As shown in Table 3, when the forged material 3 was extruded backward from the die 2, as shown in Table 3, the product of the present invention has a service life 1.2 times longer than that of the conventional product. Was obtained and the service life could be extended.

[0041]

[Table 3]

[0042]

According to the plastic working mold of the present invention, as described in claim 1, the nitrogen compound layer thickness on the surface of the base material is 10 μm or less, and at least 0.7 mm from the surface of the base material. Nitrogen concentration up to the depth position: 0.08 wt% or more, hardness from the base material surface to at least 0.7 mm depth position: 1.07 times or more of the core hardness (Hv). Therefore, the nitrogen concentration on the surface is high and the hardness on the surface is large, so that it is possible to provide a metal mold for plastic working having a further improved service life, which is a remarkably excellent effect.

Then, as described in claim 2,
By making the thickness of the nitrogen compound layer on the surface of the base material: 5 μm or less, the durability life of the plastic working die is improved when the amount of the nitrogen compound layer, which has been conventionally excellent in wear resistance, decreases. Although it was said that it could not be expected, the hardness of the core is 1.0 which has a martensite or martensite + bainite structure in which nitrogen is supersaturated as a solid solution.
By forming the diffusion layer having a thickness of 7 times or more, it is possible to obtain a remarkably excellent effect that the service life of the plastic working die can be further improved.

Further, as described in claim 3, the nitrogen concentration from the surface of the base material to the depth position of at least 0.7 mm: 0.10% by weight or more, the plastic working is performed. The remarkable effect that the service life of the working die can be further improved is brought about.

Further, as described in claim 4, hardness from the surface of the base material to a depth position of at least 0.7 mm:
By setting the core hardness (Hv) to 1.10 times or more, it is possible to further improve the service life of the plastic working die, which is a remarkably excellent effect. Be brought.

And, as described in claim 5,
By providing a nitrogen diffusion layer having supersaturated nitrogen martensite on the surface of the base material, the service life of the working die should be further improved even when the surface has a low nitrogen compound layer. As described in claim 6, the nitrogen diffusion layer depth on the surface of the base material is 0.75 mm or more. The improvement has the significant advantage that it can be more substantial.

Further, as described in claim 7, the base material component, in% by weight, is C: 0.30 to 0.60%, S
i: 1.20% or less, Mn: 1.00% or less, P: 0.
030% or less, S: 0.030% or less, Cr: 2.0 to
6.0%, the balance being Fe and impurities, and in some cases, as described in claim 8, the base material component further contains W: 0.5 to 6.0%, Mo: 0. .3 ~
3.0%, V :: 0.3 to 3.0%, Ti: 0.3 to
3.0%, Nb + Ta: 0.3 to 3.0%, Co: 0.
By containing one or more of 3 to 2.0%, a remarkably excellent effect that it is possible to provide a metal mold for plastic working having a more excellent service life is brought about.

Further, as described in claim 9,
By making the plastic working mold according to the present invention a warm plastic working or hot plastic working mold,
A remarkably excellent effect is brought about, in that it can be made suitable as a metal mold for plastic working having a smaller burden than that of cold plastic working.

According to the method for manufacturing a plastic working die according to the present invention, as described in claim 10, after the forming die base material is subjected to nitriding treatment, quenching / Tempered, nitrogen compound layer thickness on base material: 10μ
m or less, nitrogen concentration from the base material surface to at least 0.7 mm depth position: 0.08 wt% or more, hardness from the base material surface to at least 0.7 mm depth position: core hardness (H
v) is 1.07 times or more, and a nitrogen diffusion layer containing a martensite structure having a supersaturated nitrogen martensite or a martensite + bainite structure is formed, so that the surface has a large nitrogen content, This has a remarkably excellent effect that it is possible to manufacture a plastic working mold having a high hardness and a further improved service life.

Further, as described in claim 11, the nitrogen compound layer thickness on the surface of the base material is 5 μm or less, whereby the service life of the plastic working die is further improved. It has the outstanding advantage that it can be customized.

Further, as described in claim 12,
By making the nitrogen concentration from the surface of the base material to a depth of at least 0.7 mm: 0.10% by weight or more, the service life of the plastic working die can be further improved. It has the remarkable advantage of being possible.

Further, as described in claim 13,
Hardness from the surface of the base material to a depth of at least 0.7 mm: 1.10 times or more the hardness (Hv) of the core, so that the service life of the plastic working die is further improved. It has a remarkable advantage that it can be customized.

Further, as described in claim 14, by making the nitrogen diffusion layer depth on the surface of the base material: 0.75 mm or more, the service life of the plastic working die is further improved. The significant advantage is that it can be sufficient.

As described in claim 15,
Base material component is% by weight, C: 0.30 to 0.60%, S
i: 1.20% or less, Mn: 1.00% or less, P: 0.
030% or less, S: 0.030% or less, Cr: 2.0 to
6.0%, the balance consisting of Fe and impurities, and in some cases, as described in claim 16, the base material component further contains W: 0.5 to 6.0%, M.
o: 0.3 to 3.0%, V: 0.3 to 3.0%, Ti:
0.3-3.0%, Nb + Ta: 0.3-3.0%, C
o: It is remarkably excellent that it is possible to manufacture a plastic working die having a more excellent service life by applying it to one containing one or two or more of 0.3 to 2.0%. The effect is brought.

[Brief description of drawings]

FIG. 1 is an explanatory view illustrating a heat treatment pattern that can be adopted in a method for manufacturing a plastic working die according to the present invention.

FIG. 2 is a schematic cross-sectional explanatory view of the surface of a die base material obtained by the method for producing a plastic working die according to the present invention.

FIG. 3 is a schematic cross-sectional explanatory view of the surface of a die base material obtained by a method for producing a plastic working die according to a conventional example.

FIG. 4 is an explanatory view showing a heat treatment pattern adopted in an example of a method for manufacturing a plastic working die according to the present invention.

FIG. 5 is an explanatory view showing a heat treatment pattern adopted in a comparative example of the present invention in a method of manufacturing a plastic working die according to a conventional example.

FIG. 6 is a graph showing the execution results of Examples 1 to 4 of the present invention and Comparative Examples 1 and 2.

FIG. 7 is a cross-sectional explanatory view showing a rear extrusion punch, which is a metal mold for plastic working adopted in Example 5 and Comparative Example 3 of the present invention, together with a die and a material to be forged.

FIG. 8 is an explanatory view illustrating a heat treatment pattern that can be adopted in a method for manufacturing a plastic working die according to a conventional example.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C22C 38/18 C22C 38/18 38/30 38/30 C23C 8/26 C23C 8/26 // B29C 33/38 B29C 33/38

Claims (16)

[Claims] 1. A nitrogen compound layer thickness on the surface of a base material: 10 μm or less, a nitrogen concentration from the surface of the base material to a position at least 0.7 mm deep: 0.08 wt% or more, a depth of at least 0.7 mm from the surface of the base material. Hardness up to position: 1.07 times or more of core hardness (Hv), a metal mold for plastic working. 2. The metal mold for plastic working according to claim 1, wherein the thickness of the nitrogen compound layer on the surface of the base material is 5 μm or less. 3. The mold for plastic working according to claim 1 or 2, wherein the nitrogen concentration from the surface of the base material to a position at a depth of at least 0.7 mm is 0.10% by weight or more. 4. The plastic working according to claim 1, wherein the hardness from the surface of the base material to a depth of at least 0.7 mm is 1.10 times or more the hardness (Hv) of the core portion. Mold for. 5. The plastic working mold according to claim 1, wherein a nitrogen diffusion layer having supersaturated nitrogen martensite is formed on the surface of the base material. 6. The depth of the nitrogen diffusion layer on the surface of the base material: 0.75 mm
The mold for plastic working according to claim 5, which is the above. 7. A base material component, in% by weight, is C: 0.30.
0.60%, Si: 1.20% or less, Mn: 1.00%
Hereinafter, P: 0.030% or less, S: 0.030% or less,
The metal mold for plastic working according to any one of claims 1 to 6, wherein Cr: 2.0 to 6.0%, the balance being Fe and impurities. 8. The base material component further comprises W: 0.5 to 6.0.
%, Mo: 0.3 to 3.0%, V: 0.3 to 3.0%,
Ti: 0.3-3.0%, Nb + Ta: 0.3-3.0
%, Co: 0.3-2.0%, 1 type, or 2 or more types, The metal mold | die for plastic working of Claim 7. 9. The plastic working mold according to claim 1, which is a mold for warm plastic working or hot plastic working. 10. A mold base material after molding is subjected to nitriding treatment, followed by quenching and tempering treatment, and a nitrogen compound layer thickness on the base material surface: 10 μm or less, at least 0.7 mm deep from the base material surface. Nitrogen concentration up to S position: 0.08 wt% or more, hardness from the base material surface to at least 0.7 mm depth position: 1.07 times or more of core hardness (Hv), and supersaturated nitrogen martens A method for producing a plastic working die, comprising forming a nitrogen diffusion layer containing a martensite structure having a site or a martensite + bainite structure. 11. The method for producing a plastic working die according to claim 10, wherein the thickness of the nitrogen compound layer on the surface of the base material is 5 μm or less. 12. The method for producing a plastic working die according to claim 10, wherein the nitrogen concentration from the surface of the base material to a depth of at least 0.7 mm is 0.10% by weight or more. 13. Hardness from the surface of the base material to a depth of at least 0.7 mm: 1.10 times the core hardness (Hv) or more,
The method for manufacturing a plastic working die according to any one of claims 10 to 12. 14. The depth of the nitrogen diffusion layer on the surface of the base material: 0.75 m
The method for manufacturing a plastic working die according to any one of claims 10 to 13, wherein m is at least m. 15. A base material component, in% by weight, C: 0.30 to 0.30.
0.60%, Si: 1.20% or less, Mn: 1.00%
Hereinafter, P: 0.030% or less, S: 0.030% or less,
The method for producing a plastic working die according to any one of claims 10 to 14, wherein Cr: 2.0 to 6.0%, the balance being Fe and impurities. 16. The base material component further comprises W: 0.5-6.
0%, Mo: 0.3 to 3.0%, V: 0.3 to 3.0
%, Ti: 0.3 to 3.0%, Nb + Ta: 0.3 to
The method for manufacturing a plastic working die according to claim 15, comprising one or more of 3.0% and Co: 0.3 to 2.0%.