JP2001073087A - Nitrided die for warm and hot working, excellent in wear resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nitrided die for warm and hot working, as a die to which nitriding treatment is applied and which has high hardness of nitrided layer and softening resistance of nitrided layer and excellent wear resistance. SOLUTION: The nitrided die for warm and hot working has a composition which consists of, by weight, 0.25-0.55% C, <=1.2% Si, <=1.5% Mn, <=2.0% Ni, 6.0-8.0% Cr, either or both of W and Mo in amounts within the range satisfying 1/2W+Mo<=5.0%, and the balance Fe with inevitable impurities and in which Cr and Mo satisfy Cr/Mo<=3. Moreover, carbides unentered into solid solution with >=0.1 μm grain size comprise >=1% of the structure surface by area ratio, and further, a nitrided layer is provided at least to the contact surface to be brought into contact with a material to be worked, and the hardness in a position at a depth of 25 μm from the surface of the nitrided layer is regulated to >=1100 HV. Further, V, Nb, N, Co, and Al can be added to the composition of the base material, if necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hot or hot metal of various dimensions which has a high heating temperature due to frictional heating and contact with a workpiece during use, and the mold surface is subjected to a remarkable wear action due to thermal softening. It relates to a forging die.

[0002]

2. Description of the Related Art A mold for warm or hot working (hereinafter referred to as a mold)
Conventionally, materials with excellent high-temperature strength and hot wear resistance, such as SKD61, SKD7, and SKD8, have been used for molds, and are used under severer operating conditions and require more wear resistance. For these, those obtained by applying a surface treatment such as nitriding to the surfaces of these improved steels and molds have been used.

However, in recent years, in the field of plastic working, net shape and near net shape have been actively promoted, and forging techniques for increasing the forging speed to shorten the molding cycle have been put into practical use. Heat generation due to friction between the workpiece and the work material becomes more severe, thermal softening on the mold surface is remarkably early, leading to abrasion, and the life of the mold is remarkably reduced. More cases.

[0004] However, a development approach for improving the wear resistance of a hot working mold that has been conventionally performed is as follows.
Most of them focus on characteristics such as high-temperature strength and toughness of the mold material itself, and when nitriding is applied to these materials, the wear resistance of the mold, that is, the life of the mold depends on the characteristics of the base material. Examples have been reported in which the characteristics fluctuate more largely due to the nitriding characteristics than in the case.

[0005]

The improvement of the wear resistance of the hot working mold by the application of the nitriding treatment is mainly attributable to the improvement of the slidability by the nitride compound layer formed on the outermost surface of the nitriding layer. The hardness is increased by the suppression of heat transfer, the penetration of nitrogen and the precipitation of fine nitrides generated by bonding with the alloy element dissolved in the matrix, and the hardness is increased. The thickness of the nitrided compound layer can be controlled by the conditions of the nitriding treatment, but the hardness of the latter nitrided diffusion layer is almost specified by the alloy component dissolved in the matrix. That is, the hardening of the nitrided diffusion layer of the hot working mold material is mostly caused by the precipitation of nitride generated by the bonding of nitrogen and the alloying element dissolved in the matrix.

Accordingly, the present inventors have focused on the wear resistance of a mold on the premise of applying a nitriding treatment, and studied the effects of the nitride layer hardness and the heat softening characteristic and the amount of undissolved carbide on the wear resistance. With respect to abrasion resistance, extremely high nitride layer hardness and nitride layer softening resistance can be obtained without lowering the high temperature strength and toughness of the base material compared to the conventional 5Cr steel SKD61 and the like. It has been found that there is a composition that can improve wear resistance depending on the amount of undissolved carbide.

The effect of increasing the strength and wear resistance of a hot working mold by nitriding is described in JP-A-54-50421, JP-A-54-56913, and JP-A-54-110916. Is disclosed. However, these are limited to the description of mold steel in which a high surface hardness and a deep nitrided layer are easily obtained when a nitriding treatment is performed, limit the hardness of the nitrided layer, improve the resistance of the nitrided layer to softening, There is no description of enhancing the wear resistance of the mold.

The limitation of undissolved carbides for the purpose of preventing mold wear is disclosed in Japanese Patent Application Laid-Open No. H6-145884. However, in combination with a hardened nitride layer, the wear resistance is synergistically reduced. There is no description to improve the performance.

As described above, an object of the present invention is to provide an extremely high nitrided layer hardness and extremely high hardness by performing an alloy design in consideration of both characteristics of a nitrided layer and a base material on a mold on the premise of a nitriding treatment. An object of the present invention is to provide a nitrided mold for hot working that has a nitride layer softening resistance and an appropriate amount of undissolved carbide and has excellent wear resistance.

[0010]

SUMMARY OF THE INVENTION The present invention focuses on the wear resistance of a mold on the assumption that a nitriding treatment is applied, and examines the effects of the nitride layer hardness and the heat softening characteristic and the amount of undissolved carbide on the wear resistance. As a result, extremely high nitride layer hardness and nitride layer softening can be achieved without lowering the high temperature strength and toughness of the base material compared to conventional steel by lowering the high temperature strength and toughness of the base metal by balancing the amounts of the various alloy elements with respect to the wear resistance. It has been found that there is a composition that can provide resistance and that can improve wear resistance depending on the amount of undissolved carbide. By using the mold of the present invention having both excellent nitriding characteristics and base material characteristics, it is possible to improve the number of wear lives of the mold in which damage due to wear is a problem.

That is, in the present invention, C: 0.25 to 0.5% by weight.
5%, Si: 1.2% or less, Mn: 1.5% or less, Ni: 2.0% or less, Cr: 6.0
~ 8.0%, one or two kinds of W and Mo are less than 5.0% at 1 / 2W + Mo, and Cr and Mo satisfy Cr / Mo ≦ 3, and the balance consists of Fe and unavoidable impurities. The area ratio of the undissolved carbide having a particle size of 0.1 μm or more is 1% or more, and has a nitrided layer on at least a contact surface with a workpiece, and 25% from the surface of the nitrided layer.
This is a nitride mold for hot working with a hardness of 1100HV or more inside μm.

Further, a nitride mold for hot working containing V: 2.0% or less or Nb: 0.30% or less, preferably,
N: A mold for warm working containing 0.10% or less.
And, in addition to these inventions, Co: 10.0% or less or A
l: A hot working mold containing 3.0% or less.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, an important feature of the mold of the present invention is that various alloying elements, particularly Cr / Mo equivalents, are balanced with respect to a mold premised on nitriding treatment. This is a nitrided mold for hot working that has the same high-temperature strength and toughness as conventional steel, has greatly improved nitriding properties, and has excellent wear resistance. The reasons for limiting the component range of the mold of the present invention will be described below.

1) CC is an important element that imparts excellent wear resistance to the mold of the present invention, and combines with carbide-forming elements such as W, Mo, V, and Cr to form carbides. In addition to increasing the abrasion resistance by dispersing partly as undissolved carbide in the base metal matrix,
The compound is added to facilitate the formation of a compound layer during nitriding, which contributes to the improvement of the wear resistance of the mold of the present invention, and further improves hardenability, refines crystal grains, and provides resistance to tempering softening. In order to obtain the effect described above, it is necessary to add at least 0.25% or more. If it is too large, precipitation of excessive carbides is caused and the toughness is reduced, so the content is made 0.55% or less. Preferably, it is 0.40% or less.

2) Si and Mn Si are added to impart a deoxidizing agent and a mold with oxidation resistance, and further contribute to an improvement in nitriding hardness. If it is too large, the toughness during tempering is reduced, so that the content is made 1.2% or less. Note that the content is preferably 0.1% or more for obtaining the above effects. Mn is added for desulfurization agent and improving hardenability, when too much lowering the A ₁ transformation point, excessively high annealing hardness, and 1.5% or less since lowering machinability. Note that the content is preferably 0.1% or more for obtaining the above effects.

3) Ni Ni, together with C, Cr, Mn, Mo, W, etc., imparts an excellent hardenability to the mold of the present invention, and prevents a decrease in toughness due to a decrease in the quenching cooling rate, Is added as necessary because the essential toughness can be improved. If too much,
A _{1 To make the} transformation point excessively low or to excessively increase the annealing hardness to lower the machinability, the content is made 2.0% or less.
Note that the content is preferably 0.1% or more for obtaining the above effects.

4) Cr Cr is the most important element that imparts excellent wear resistance to the mold of the present invention, and combines with C to form carbides to improve wear resistance. Solid solution in
A fine and high-hardness nitride is formed in the diffusion layer by the combination of Cr and nitrogen, thereby improving the surface hardness and the softening resistance of the nitride layer of the mold of the present invention and contributing to the improvement of wear resistance. In addition, it improves tempering softening resistance and high-temperature strength, and improves hardenability.
Further, a dense oxide film is formed at the time of use, and the hot slidability of the mold surface is improved. If the amount is too large, the high-temperature strength and the softening resistance are lowered. If the amount is too small, the target nitriding hardness cannot be obtained, so the Cr content is set to 6.0 to 8.0%. Further, in order to obtain the above characteristics, the Cr / Mo equivalent is specified to be 3 or less.

5) W, Mo W and Mo are important for maintaining the amount of undissolved carbide effective for improving the high temperature strength, softening resistance and wear resistance required for the use of the mold of the present invention. In addition, Mo contributes to the improvement of the hardness of the nitrided layer. W and Mo combine with C to form strong carbides, and at the time of quenching, some remain as undissolved carbides and contribute to wear resistance. Precipitating fine special carbides,
Improves high-temperature strength and softening resistance. Further, Mo easily forms carbonitride during the nitriding treatment, increases the nitriding hardness which is a feature of the mold of the present invention, and contributes to the improvement of wear resistance. However, if it is too large, it not only causes excessive carbide precipitation and lowers toughness, but also lowers machinability, so it is necessary to add it according to the use conditions and nitriding characteristics of the mold. One or two types of W and Mo should be less than 5.0% by 1 / 2W + Mo. Further, the Cr / Mo equivalent is specified to be 3 or less in order to suppress a decrease in high-temperature strength and softening resistance due to the addition of Cr. That is, the addition amount of Mo must be at least 2.0% or more.

6) VV is effective for improving the wear resistance and seizure resistance by forming carbides which are hardly dissolved and improving the hardness of the nitrided layer, and contributes to the improvement of the wear resistance of the mold of the present invention. I do. At the time of quenching, it forms a solid solution in the matrix, precipitates fine hard-to-aggregate carbide during tempering, increases softening resistance, and improves high-temperature proof stress. Furthermore, it has the effect of raising the By improving toughness by refining crystal grains at the same time the A ₁ transformation point. However, if it is too large, not only will a large carbide be generated and the toughness will be deteriorated, but also the appearance of banded segregation zones of carbide formed along the working direction will be increased, and cracks will be promoted along that direction. Therefore, it is set to 2.0% or less. In order to obtain the effect of the above addition, it is desirable to add 0.2% or more.

7) Nb Nb forms a carbide which hardly forms a solid solution like V and improves wear resistance and seizure resistance. At the same time, Nb forms a solid solution in a matrix during quenching treatment and finely aggregates during tempering. Precipitates difficult carbides to increase softening resistance and improve high temperature proof stress. Further, the growth of crystal grains during quenching and heating is suppressed, and the crystal grains are refined to improve toughness. However, if the content is too large, a large carbide is generated and the toughness is deteriorated. Note that the content is preferably 0.02% or more for obtaining the above effects.

8) Like NN, NN combines with V, Nb, etc. to form carbonitrides, refines crystal grains, and improves toughness. It is effective to add. Addition is carried out in order to obtain the above-mentioned effects. However, if it is too much, it promotes crystallization of giant carbides, and the content is made 0.10% or less in consideration of productivity during smelting and ingot making. Note that the content is preferably 0.02% or more for obtaining the above effects.

9) Co Co enhances the solid solution strengthening and softening resistance of the base material, and at the same time raises the temperature during use, forms an extremely dense and highly adherent oxide film, and makes metal contact with the molding material. To prevent the temperature of the mold surface from rising, and to improve the wear resistance. Co may be added as needed to impart the above effects, but if too large, the toughness is reduced by 10.0%.
The following is assumed. Preferably it is 5.0% or less.

10) Al Al forms a hardened nitride by forming a solid solution in the matrix and combining with N in the steel and has a function of strengthening the precipitation. further,
During nitriding, Al dissolved in the matrix combines with nitrogen to precipitate fine and hard nitrides in the nitrided layer, improving the surface hardness of the mold of the present invention and contributing to the improvement of wear resistance. . However, excessive addition causes a decrease in the strength of the base material and a decrease in the toughness of the nitrided layer. Note that the content is preferably 0.2% or more to obtain the above effect.

Next, the reasons for limiting the amount of undissolved carbide in the mold of the present invention will be described. Wear of the nitriding warm or hot working mold occurs due to various factors, but the surface layer softens due to the heat generated by friction between the mold surface and the high temperature workpiece, causing plastic flow. This is one of the major factors. When the frictional heat is large, the nitride compound layer formed on the outermost layer of the nitride layer diffuses and disappears at an early stage, and when the temperature exceeds the transformation point of the mold material, a re-quenched layer may be formed on the mold surface layer.

The improvement in the sliding property and seizure resistance with the work material by increasing the amount of carbide dispersed in the base material can be attained by using a high-speed tool steel containing a large amount of primary carbide having a particle size of 2 μm or more. Is generally well known. on the other hand,
During quenching, most carbides form a solid solution in the matrix, and the diameter of undissolved carbides is around 1μm or less, and the area ratio is around 3% or less. In addition, it has been found that nitriding can improve the surface hardness by nitriding and increase the amount of undissolved carbides, thereby synergistically improving wear caused by friction with the workpiece in a high temperature range.

Based on these findings, the optimum conditions were examined. In the mold of the present invention, the undissolved carbide remaining after quenching, for example, at 1030 ° C., had a grain size of 0.1 μm or more occupying the structure surface. It has been found that it is effective to set the area ratio of the above to 1% or more. The amount of undissolved carbide is determined by the carbide forming elements C, Cr, W, Mo,
The amount can be increased without limitation by increasing the amount of V and Nb added. However, in view of the toughness of the base material and the material cost, setting the upper limit thereof also sets the upper limit of the amount of undissolved carbide. Specifically, it is appropriate that the upper limit of the area ratio is 5%.

Next, the reasons for limiting the hardness of the nitrided layer of the mold of the present invention will be described. One of the reasons why the wear resistance of the mold is improved by the nitriding treatment is that nitriding hardened due to penetration of supersaturated nitrogen into the mold material surface and precipitation of fine nitrides by bonding with alloying elements dissolved in the matrix. This is because the formation of the diffusion layer significantly improves the high-temperature strength of the mold surface as compared with the base material.

On the other hand, the softening in the vicinity of the surface of the mold subjected to the nitriding treatment causes the temperature of the mold surface to rise due to the heat transfer due to the contact between the mold surface and the workpiece and the heat generated by the friction, and nitrogen is formed inside the mold. The softening resistance of the nitrided layer depends on the initial hardness of the nitrided layer. In other words, when the nitride layer is affected by the heat under the same conditions, the lower the initial hardness of the nitride layer, the lower the absolute value of the hardness after softening, which is disadvantageous to the wear of the mold.

As a result of these studies, it was found that 25
If the hardness of the nitrided layer within 1 μm is less than 1100 HV, the period from softening and abrasion to the disposal of the mold becomes short, so the hardness of the nitrided layer within 25 μm from the surface of the nitrided layer is reduced. Limited to 1100HV or more. Note that the term “nitriding” used herein is not particularly limited as long as the above characteristics can be obtained.

[0030]

EXAMPLES (Example 1) Hereinafter, the present invention will be described in detail with reference to examples. Table 1 shows the chemical components of the test piece materials used in the experiment. All the test pieces collected from each material of the mold of the present invention and the comparative mold were heated at 1030 ° C., quenched in oil at 200 ° C., and then tempered to about 50 HRC by tempering. Further, for the test piece used for evaluating the characteristics of the nitrided layer, after performing the same heat treatment as described above, 540
A nitriding treatment was carried out at a temperature of 20 ° C. and a gas composition of NH ₃ : N ₂ = 1: 1 to obtain a test material. Each test piece was prepared from this, and the base material toughness,
The base metal high-temperature strength, the initial hardness of the nitride layer, and the softening resistance of the base material and the nitride layer were evaluated.

[0031]

[Table 1]

For evaluation of base metal toughness, a JIS No. 3 test piece (2 mm U notch) was prepared and subjected to a Charpy impact test at room temperature. The base metal high-temperature strength was evaluated by tensile strength by immediately performing a tensile test after heating and holding at 700 ° C. for 10 minutes. The initial hardness of the nitrided layer was evaluated by cutting a test piece immediately after the nitriding treatment and measuring the hardness at a position 25 μm from the surface subjected to the nitriding treatment by a micro Vickers test 2.942N specified in JIS.

With respect to the softening resistance of the nitrided layer and the base material, the nitrided test pieces were held in air atmospheres at 650 ° C. and 700 ° C. for 3 hours each, and then cut and cut under the same conditions as described above. Hardness measurements were taken. However, since heating in the air involves denitrification from the surface of the test piece, the measurement of the softening hardness of the nitrided layer was evaluated at the highest hardness within the range of 25 to 100 μm from the surface. Regarding the hardness measurement after the softening test of the base material, the same measurement as described above was performed at a position 5 mm from the surface layer where the nitride layer of the test piece was not affected. Table 2 shows the test results for each steel.

[0034]

[Table 2]

The Charpy impact values of the mold of the present invention—steel 1 to 5 are equivalent to those of the conventional steels shown in Comparative Examples—steel 6 and 7,
It turns out that it has sufficient toughness as a mold for warm or hot forging. The high-temperature strength (700 ° C tensile strength) is shown in Fig. 1 organized by the amount of Cr added to each steel. In the figure, the high-temperature strength of Comparative Example-Steel 6 to 8 is indicated by a broken line, but in the case of the conventional steel, the high-temperature strength decreases with an increase in the Cr content,
It can be seen that when it exceeds 5%, it drops to 300 MPa or less. On the other hand, the mold of the present invention regulates the Cr / Mo equivalent to 3 or less and compensates for the high-temperature strength, which is reduced by the increase in Cr amount, by the Mo amount. It has a strength of 300 MPa or more, and the hardness of the nitrided layer is 1100 HV or more without lowering the high-temperature strength compared to conventional steel as shown in the hardness of the nitrided layer before the test in Fig. It can be seen that it has improved up to.

Next, FIGS. 2 and 3 show the hardness immediately after the nitriding treatment of the base material and the nitrided layer, 650 ° C. × 3 h (−−− in the figure), and 700 ° C.
× 3h (-*-in the figure) shows the results of the hardness after the softening test arranged by the amount of Cr added. From FIG. 2, it can be seen that the softening characteristics of the base material tend to decrease in hardness as the Cr content increases, similarly to the high-temperature strength. Comparative Example-The hardness of the steel 8 before the test was reduced to about 440 HV as compared with the others, which was due to softening during the nitriding treatment.

On the other hand, the change in hardness of the nitrided layer shown in FIG.
It can be seen that, unlike the softening behavior of the base material, the higher the hardness of the nitrided layer before the test, the higher the hardness is maintained after the softening test. However, even if the hardness of the nitrided layer before the test was 1100 HV or more, as shown in Comparative Example-Steel 8, Cr
It can be seen that when the / Mo equivalent is 3 or more, the softening of the nitrided layer is large. As a result, the mold of the present invention significantly improved the hardness and softening resistance of the nitrided layer without reducing the toughness and high-temperature strength of the base material as compared with the conventional steels shown in Comparative Examples-Steels 6 and 7. You can see that it is doing.

(Example 2) Next, the results of evaluating the effect of the amount of undissolved carbide on the slidability and seizure properties during hot working will be described. Prepare a material of the composition of steel 1 to 8 shown in Table 1, after heating at 1030 ℃, immersion in oil at 200 ℃ oil quenching, tempered to 50HRC by tempering, 540 ℃ by gas nitriding Nitriding was performed under the conditions of × 20 h and a gas composition of NH ₃ : N ₂ = 1: 1 to obtain a test material.

The dimensions of the test piece were 5 mm in diameter and 30 mm in length, and 154 mm was placed on the # 1000 finished surface of SNCM439 steel heated at 600 ° C. for 30 minutes.
The specimen was pressed with a predetermined load at a rotation speed of 0 rpm, and the contact surface of the test piece was re-quenched, and a high-temperature sliding test evaluation was performed using a load at which buckling occurs as a limit load. The amount of undissolved carbide in the comparative mold and the mold of the present invention was 240 μm in area by 10,000 times SEM observation.
It was evaluated by measuring the area ratio of undissolved carbide of 0.1 μm or more in a ² × 10 visual field.

[0040]

[Table 3]

Table 3 shows the amount of undissolved carbide, the hardness of the nitrided layer (at a position 25 μm from the surface subjected to the nitriding treatment) and the results of the high-temperature sliding test of each steel. In addition, the mold of the present invention—steel 2 and the comparative example—steel 6 were also evaluated for the untreated material as a comparison. From this, it can be seen that the sliding characteristics at a high temperature are greatly improved by applying the nitriding treatment, and there is a synergistic effect of increasing the amount of undissolved carbide and the hardness of the nitrided layer.

Example 3 Hereinafter, an example in which the die of the present invention is applied to a hot backward extrusion forging die will be described. A raw material having the composition of steels 1 to 7 shown in Table 1 was prepared, a hot backward extrusion forging die was manufactured from this, and an actual forging test was performed. The mold is a punch for extruding an automobile part material backward, and has a diameter of 100 mm and a height of 310 mm. Forging temperature is 1150 ℃, maximum capacity 150
Molding was performed at a speed of 40 shots per minute with a 0t crank press.

The heat treatment of each mold is carried out by
After heating at 30 ° C, oil quenching immersed in oil at 200 ° C, tempered by tempering to about 50HRC, and finished. The nitriding treatment was performed on all the dies, and the nitriding treatment was performed by gas nitriding under the conditions of 540 ° C. × 20 hours and a gas composition of NH ₃ : N ₂ = 1: 1. Table 4 shows the tool life of these hot forging dies based on the results of the actual machine forging test.

[0044]

[Table 4]

In the present forging die, since the molding speed is high, the sliding speed between the workpiece and the die is high, and the surface layer is softened and abraded due to frictional heat, and the life is quickly reached. In the mold of the present invention, the wear life of the mold was significantly improved by improving the hardness of the nitrided layer, the resistance to softening, and further increasing the amount of undissolved carbide.

[0046]

As described above, the warm or hot working mold of the present invention has excellent wear resistance as compared with the conventional mold and has a long wear life of the warm or hot forging mold. It can be greatly improved, and the industrial value is great.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of the amount of Cr added on high-temperature strength represented by tensile strength at 700 ° C.

FIG. 2 is a graph showing the relationship between the hardness of the base metal and the amount of Cr added immediately after the nitriding treatment (before the test) and at 650 ° C. and 700 ° C. for 3 hours for each softening treatment.

FIG. 3 is a graph showing the relationship between the hardness of a nitrided layer and the amount of Cr added immediately after nitriding treatment (before the test) and at 650 ° C. and 700 ° C. for 3 hours and softening treatment.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C22C 38/52 C22C 38/52 C23C 8/26 C23C 8/26 F term (reference) 4E050 JA01 JB09 JD05 4E087 AA09 AA10 CB01 CB02 EC01 ED04 ED06 4K028 AA02 AB01 AB06 AC08

Claims (6)

[Claims] C .: 0.25 to 0.55%, Si: 1.2% or less, Mn: 1.5% or less, Ni: 2.0% or less, Cr: 6.0 to 8.0%, W and Mo
1% or 2 types is less than 5.0% at 1 / 2W + Mo, and Cr and Mo are Cr /
Satisfies Mo ≦ 3, the balance consists of Fe and unavoidable impurities, and the area ratio of undissolved carbide with a grain size of 0.1 μm or more occupying the structure surface is 1% or more. A nitride mold for hot working having excellent wear resistance, comprising a layer and having a hardness of 1100 HV or more within 25 μm from the surface of the nitride layer. 2. The nitride mold for hot working with excellent wear resistance according to claim 1, which contains V: 2.0% or less by weight. 3. The nitride mold for hot working with excellent wear resistance according to claim 1, wherein the mold contains Nb: 0.30% or less by weight. 4. The nitride mold for hot working with excellent wear resistance according to claim 2, which contains N: 0.10% or less by weight. 5. The nitride mold for hot working with excellent wear resistance according to claim 1, which contains, by weight percent, Co: 10.0% or less. 6. The nitride mold for hot working excellent in wear resistance according to claim 1, which contains, by weight%, Al: 3.0% or less.