JPH10219423A - Member for warm and hot working and production therefor as well as metal mold for warm and hot working formed by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member for warm and hot working, such as for machine parts, having sliding parts to be used warm and hot, a process for producing the same and a metal mold for warm and hot service formed by using the same. SOLUTION: This member for warm and hot working has a mixture layer consisting of iron sulfide particles and iron nitride particles on the surface layer part of the member. The region where the weight concn. ratio (S/N) of the sulfur and nitrogen in the mixture layers satisfies the equation 0.5<S/N<10 exists in the mixture layer. The member body side preferably has an intermediate layer consisting of iron sulfide, iron nitride and iron oxide. Further, at least a nitrided layer is preferably formed on the member body side of the intermediate layer. The member is adequate for the metal mold for warm and hot working.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot or hot member used warm or hot, a method for manufacturing the same, and a hot mold using the same.

[0002]

2. Description of the Related Art Conventionally, for example, a mold for hot forging (hereinafter, referred to as a forging die).
The mold is mainly used for SKD6 specified in JIS.
1, hot tool steels represented by SKT4 are used. In particular, for applications requiring durability, SKD7, SKD8, high-speed steels or higher-grade steels having higher hot strength than these are used. ing. In recent years, in response to demands for higher precision and improved processing efficiency of products to be processed, surface treatment is generally performed to maintain the toughness of the mold and to provide wear resistance and seizure resistance to the mold surface. Is being applied. As a surface treatment method performed on such a mold, a single nitriding treatment by an ion method, a salt bath method, a gas method, or the like is mainly used.

For example, Japanese Patent Application Laid-Open No. 7-138733 discloses that
In order to reduce heat crack resistance and plastic flow of the mold, the temperature is raised to 950 ° C after ion nitriding and high-frequency heating is used to reduce the fragile, high-concentration nitrogen compounds called the white layer on the outermost surface. A method has been proposed in which the nitrogen diffusion layer is deepened to 3.0 mm. Also, Japanese Patent Application Laid-Open No. 57-54
No. 551 proposes a hot working mold that performs ion nitriding at a low temperature (350 to 450 ° C.) for the purpose of preventing seizure while maintaining the toughness of the mold core. Has a mold life of 2 times compared with the conventional nitriding material.
This is an improvement of the mold life of about 30%, which is not necessarily a dramatic improvement of the mold life.

[0004] In recent years, near-net shaping has resulted in a complicated product shape and a large flow of material during processing.
The friction with the working surface of the mold becomes excessive, the surface of the mold is softened more by the frictional heat, and the transformation point of the mold itself (700 to
(900 ° C.).
As a result, the properties that the mold itself should have are lost, the high-temperature properties are significantly reduced, and the mold wear phenomenon is accelerated to shorten the life. In addition, in molds that have been subjected to a single nitridation treatment, such as ion nitridation, which is currently performed as the mainstream of surface treatment, part of the formed nitride is decomposed due to overheating, and the effect is not sufficient. There was a problem that it could not be demonstrated.

[0005] As a method other than the single nitriding treatment, Japanese Patent Application Laid-Open No. 4-228557 discloses a method for improving lubricating oil holding properties of pistons and cylinders used in hydraulic pumps and motors of construction machinery. Gas sulphonitriding methods and devices have been proposed for cold sliding members used in. Further, the proposal of JP 60-39155, to form a first layer consisting of introducing a decomposition gas and ammonia gas ammonium sulfide, mainly sulphide ferric on the surface of the iron-based products (FeS _2), The second layer has a structure in which Fe ₄ N iron nitride is formed.

Also, Katagiri et al. (The Institute of Metals, Vol. 51, No. 1
0 (1987), p. 930 to 934) use a colorless ammonium sulfide solution, a hydrogen sulfide concentration of 150 ppm,
Ammonia concentration 75%, processing temperature 580 ° C, processing time 1
By subjecting the steel material to a nitrosulphurizing treatment under conditions of up to 6 hours, a porous ferrous sulfide (FeS) layer is formed on the outermost surface, and a surface in which iron oxide (Fe ₃ O ₄ ) coexists It is reported that a layer was obtained.

Further, Kabasawa (Heat Treatment 36, 6 (19
96), p. 383-387) is, H _2, which was diluted with N ₂
Several types of processing cycles using S cylinder, pure N ₂ cylinder, and pure NH ₃ cylinder show a gas nitrocarburizing cycle using CO ₂ cylinder for the three kinds of cylinders. A black lubricating layer having solid lubricity is formed on the compound layer, and the FeS, Fe _1-x S of the vulcanizing layer is
It has been reported that sulfur differs from nitrogen in that it has almost no solid solubility limit for α-Fe, so the sulfurized layer of FeS, Fe _1-x S is limited to the surface of steel and does not diffuse inside. I have. In addition, in Japanese Patent Publication No. 7-42566, ferrous oxide (F) is used for the purpose of preventing corrosion under underground burial such as bolts and nuts made of mild steel and cast iron, or for preventing rust and improving the appearance of the ground.
There has been proposed a method of forming iron oxide in which e ₃ O ₄ ) is formed on a base material.

[0008]

Generally, the wear of a metal mold during plastic working of a high-temperature workpiece proceeds in the following course. The mold surface receives a thermal shock due to the following contact with the workpiece. That is, the surface of the high-temperature workpiece is pressed strongly onto the mold working surface, flows along the die-sculptured surface, and undergoes plastic working while generating frictional heat and generating heat due to plastic deformation. During this operation, the surface of the mold rapidly rises in temperature and expands. When the work is completed, the workpiece is quickly released from the mold. The mold surface starts to cool at the same time as the workpiece is released, and contracts.

As a result of the repetitive plastic working of the material to be processed as described above, not only the mold surface is subject to thermal fatigue due to expansion and contraction, but also the mold surface softened by heat is affected by the processing stress and The resistance to the stress generated due to expansion and contraction is reduced, and heat crack and plastic flow are likely to occur on the surface layer of the mold, and wear such as wear proceeds. At this time, especially when the surface of the mold and the workpiece are in direct contact, the seizure phenomenon is likely to occur. When seizure occurs, heat transfer from the workpiece to the surface of the mold is facilitated, and wear of the mold proceeds more rapidly.

For this reason, in a normal operation, a lubricant or a release agent is applied to the mold surface every cycle, and these are interposed in a film form between the mold surface and the workpiece.
There is an advantage that the work surface of the mold does not come into direct contact with the workpiece. On the other hand, since the above-mentioned cooling agent is applied to the heated surface of the mold, the cooling rate is increased, and the mold shrinkage per unit time is disadvantageously increased. As described above, a normal hot forging die is a single-nitrided die, and a mechanical part having a sliding portion conventionally used on a relatively low temperature side near room temperature. Has been subjected to a nitrosulphurizing treatment. Japanese Patent Application Laid-Open No. 4-228557 discloses that FeS ₂ having a high lubricating oil content is subjected to secondary heat treatment at 200 to 350 ° C., and ferrous sulfide (FeS ₂ ) is formed on the outermost surface of a steel member. It is formed to enhance the lubrication effect.

Further, Kabasawa (Heat Treatment 36, 6 (199)
6), p. 383-387) discloses that a sulfurized layer having a solid lubricating property is formed in a thickness of 3-5 μm to improve the seizure resistance and wear resistance at room temperature (20 ° C.). It is. However, for example, when a mold that has been subjected to such a treatment is formed under high pressure from a workpiece heated to a high temperature, which is a target of the present invention, ferrous sulfide or ferrous sulfide (FeS, Fe _{1 -x} S) easily peels off or falls off due to a difference in thermal expansion coefficient from the nitride layer to be joined, and is unsuitable for use as a warm-hot mold.

Further, since each layer proposed in Japanese Patent Application Laid-Open No. 60-39155 is porous, when applied to a mold, a material to be processed at a high temperature, for example, 600 ° C. or higher, is formed under a high pressure. Then, it is likely to be a starting point of a heat crack or a propagation path, which is not suitable for use. Further, the method proposed by Katagiri et al. Uses a colorless ammonium sulfide solution as a feedstock, so that the weight concentration ratio (S / O) of sulfur and oxygen in the surface layer obtained is less than 0.5, and The coefficient of friction between the surface and the work material cannot be reduced sufficiently, and as described above, it tends to be a starting point or a propagation path for heat cracks caused by the porous layer. It is not always suitable for the use of the mold.

The layer formed on the surface of the steel material by the conventional sulphiditriding method can be used when plastically working a material heated to a high temperature, such as a mold to which the present invention is applied. , Which is likely to be a starting point or a propagation path for heat cracks caused by the porous layer, or ferric sulfide (FeS ₂ )
Iron and ferrous sulfide (FeS, Fe _1-x S) were apt to be easily peeled off or dropped off due to the difference in thermal expansion coefficient from the iron nitride to be joined, and could not function sufficiently.

[0014]

When the present invention is used, for example, as a mold, the inventor can determine how heat such as heat of a workpiece heated to a high temperature or heat generated by plastic deformation is not directly transmitted to the mold surface. We examined whether it could be shut off and the life of the mold could be significantly improved. As a result, it is possible to modify the surface of the mold itself to form a dense surface treatment film that is less likely to seize between the mold surface and the workpiece, and has both a lubricating effect and a heat insulating effect. It has been found that if possible, the generation of frictional heat is suppressed, the surface of the mold is softened by heat transfer, and the life of the mold can be improved. As a result of repeated experiments on various films formed on the surface layer of the member, the inventors formed a mixture layer composed of iron sulfide particles and iron nitride particles, and particularly, a weight concentration ratio of sulfur and nitrogen in the mixture layer ( It has been found that limiting S / N) to a specific range greatly enhances the effect.

That is, the first invention of the present invention has a mixture layer composed of iron sulfide particles and iron nitride particles on the surface layer of a member, and the weight concentration ratio of sulfur to nitrogen (S /
N) is a member for warming and warming, characterized in that there is a region satisfying the expression of 0.5 <S / N <10. The second invention provides an iron sulfide particle and an iron nitride particle on a surface layer of the member. Wherein there is a region where the weight concentration ratio of sulfur to nitrogen (S / N) in the mixture layer satisfies the expression 0.5 <S / N <10, and A hot / warm member characterized in that at least a nitride layer is formed on the member body side.

According to a third aspect of the present invention, there is provided a member having a mixture layer of iron sulfide particles and iron nitride particles on a surface layer of the member, wherein a weight concentration ratio (S / N) of sulfur to nitrogen in the mixture layer is 0.5. <S /
A member for warm / hot use, characterized by having a region satisfying the equation of N <10, and having an intermediate layer composed of iron sulfide, iron nitride and iron oxide on the member body side of the mixture layer. The invention has a mixture layer composed of iron sulfide particles and iron nitride particles on the surface layer of the member, and the weight concentration ratio (S / N) of sulfur and nitrogen in the mixture layer is 0.5 <S / N <10. And a middle layer made of iron sulfide, iron nitride, and iron oxide on the member body side of the mixture layer, and at least a nitride layer is formed on the member body side of the intermediate layer. It is a member for warm and hot characterized by having.

According to a fifth aspect of the present invention, there is provided a member having a mixture layer composed of iron sulfide particles and iron nitride particles on a surface layer of the member, wherein a weight concentration ratio (S / N) of sulfur to nitrogen in the mixture layer is 0.5. <S
/ N <10, and an intermediate layer made of iron sulfide, iron nitride and iron oxide is formed between the mixture layer and the nitride layer formed on the member body side. The layer is a warm / hot member characterized by comprising a white layer and a nitrogen diffusion layer.

The concentration of S in the mixture layer is 5% by weight.
The concentration of S in the intermediate layer is preferably 1 to 10 by weight%. The thickness of the mixture layer is 0.1 to 2
It is desirable that the thickness of the intermediate layer is 0 μm and the thickness of the intermediate layer is 0.1 to 40 μm, and that the nitride layer has a maximum hardness of 800 HV or more.

A sixth aspect of the invention for producing the above-mentioned warm / hot member is as follows.
A colorless ammonium sulfide solution and a yellow ammonium sulfide solution are supplied into the gas generating vessel at a ratio of 6: 1 to 1: 1. The mixed gas of the gas on the liquid surface and the carrier gas composed of argon or nitrogen gas is supplied. Hydrogen sulfide gas concentration of 1
00 to 600 ppm, ammonia gas concentration 0.1 to
Adjust to 1.0%, arrange the hot / cold members and
The ammonia concentration in the reaction furnace is set to 20 to 70% by introducing into the reaction furnace heated to 650 ° C. and supplying argon or nitrogen gas and ammonia gas supplied from another container.
The cooling rate after holding at 600 to 650 ° C is 30 to
This is a method for producing a member for hot and warm use, wherein the member is gradually cooled to 250 ° C./Hr and subjected to a gas sulfide nitriding treatment. Further, the warming member constituted by the first to sixth inventions is preferable as a warming mold.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The first feature of the member for warming and warming of the present invention is that the member has a mixture layer composed of iron sulfide particles and iron nitride particles on the surface layer, and the sulfur and nitrogen in the mixture layer are contained in the mixture layer. The point is that the weight concentration ratio (S / N) is limited to 0.5 <S / O <10. When the sulfur / nitrogen concentration ratio (S / N) in the mixture layer is 0.5 or less, the friction coefficient between a work part and a sliding part such as a machine part or a mold working surface can be sufficiently reduced. On the contrary, in the case of 10 or more, the adhesiveness between the member or the mold body or the intermediate layer formed on the member or the mold body side of the mixture layer becomes insufficient, and the peeling or falling off becomes easy, and the Since it cannot be used, it is set to less than 10.

Further, the second feature of the warming member of the present invention is as follows.
Is characterized in that an intermediate layer composed of iron sulfide, iron nitride and iron oxide is provided between the mixture layer and the nitride layer present on the member body side. The intermediate layer is structurally located between the mixture layer and the nitride layer in the surface layer of the member, and has the effect of improving the adhesion between the layers. Further, in the case of a conventional structure having a surface layer of iron sulfide (FeS ₂ , FeS, Fe _1-x S) layer and a nitride layer, the cooling rate of the gas sulfide nitriding treatment is set to 150 ° C. / The iron sulfide layer may peel off when cooled to a temperature of at least Hr, or may easily peel off and drop off when plastically processing a high-temperature workpiece under high pressure.
Had to be kept to a point.

Another feature is that at least a nitride layer is formed on the mold body side of the mixture layer. In this case, the structure may include only the mixture layer and the nitride layer. Preferably, an intermediate layer having the above structure is interposed between the mixture layer and the nitride layer. If the adhesion between the mixture layer and the nitride layer is maintained, the intermediate layer has another structure. An intermediate layer may be interposed. The nitride layer is
More specifically, it is composed of a white layer and a nitrogen diffusion layer. The nitride layer has an effect of compensating for insufficient strength of the surface portion of the member or the mold body in the case of a member having a mating material sliding at a relatively high temperature or a mold in which a workpiece is plastically processed under high pressure. In addition, it has an effect of preventing the seizure resistance from being reduced in a short time when the mixture layer is partially worn out after long-term use.

For the same reason, the concentration of S in the mixture layer which satisfies the constitutional requirements of the first to fifth inventions of the present invention is preferably 5 to 35 by weight%. The thickness is required to be 0.1 μm in order to exert the above-mentioned effect, and conversely, if it exceeds 20 μm, it is easy to peel off, so it is desirable to form a dense layer of 0.1 to 20 μm.

The intermediate layer satisfying the constitutional requirements of the third to fifth aspects of the present invention may be a mixed layer composed of iron sulfide, iron nitride and iron oxide. Iron sulfide: iron nitride: iron oxide 20-40: 2
0 to 40: 20 to 40 is desirable. For the same reason, the concentration of S in the intermediate layer is preferably set to 1 to 10 in terms of% by weight.
1 μm is required, and conversely, if it exceeds 40 μm, it is easy to peel off. Therefore, it is desirable to form a dense layer of 0.1 to 40 μm. More preferably, the hardness of the nitrided layer is
The pressure is preferably set to 900 HV or more in order to supplement the strength of the members and the mold body.

The hot members to which the present invention is applied include, for example, rolls for forming aluminum wheels, sliding members such as rails and guides, and pins used in the warm state such as extrusion pins, core pins, and core pins. In addition to the extrusion dies, gears, molds for valve molding, hot molds for forging or press molding, and the like, members used in an atmosphere in which a workpiece or a counterpart material is exposed to a temperature of 400 ° C. or more, It is suitable as a member used at a temperature of 600 ° C. or higher, particularly 800 ° C. or higher.

In order to manufacture the hot-working member of the present invention which satisfies the above-mentioned constitutional requirements, in particular, a hot-working mold, there is a method using, for example, an ammonium sulfide solution as a source of sulfuration, oxidation and nitriding. This method is advantageous in that the weight concentration ratio (S / N) of sulfur and nitrogen in the dense mixture layer of iron sulfide particles and iron nitride particles is more than 0.5 on the surface layer of the member.

That is, a colorless ammonium sulfide solution having a low hydrogen sulfide concentration and a high water content (JI
SK8943) and a yellow ammonium sulfide solution having high hydrogen sulfide concentration and low water content (JIS K8942) to form a mixed solution, and the gas on the liquid surface generated is mixed with argon or nitrogen gas as a carrier gas. The hydrogen sulfide gas concentration is adjusted to 100 to 600 ppm, the ammonia gas concentration is adjusted to 0.1 to 1.0%, and the members to be treated are arranged and introduced into a reaction furnace heated to 600 to 650 ° C. The ammonia concentration in the reaction furnace is adjusted to 20 to 70% with argon or nitrogen gas and ammonia gas supplied from another container such as the one described above to perform sulphinitriding for a predetermined time, and the cooling rate after holding at 600 to 650 ° C. 30
What is necessary is just to cool slowly to -250 degreeC / Hr, and to process.

Here, the concentration of H ₂ S in the on-liquid gas (head gas) of the colorless ammonium sulfide solution is 30 ppm at 25 ° C., and the H ₂ S concentration in the on-liquid gas of the yellow ammonium sulfide solution is 1250 ppm. Therefore, in order to satisfy the constituent requirements to be formed on the surface layer of the member, the ratio of the colorless ammonium sulfide solution to the yellow ammonium sulfide solution is set in the range of 6: 1 to 1: 1 and H _{2 in the} gas above the liquid surface is adjusted.
The S concentration is in the range of 100 ppm to 600 ppm.

In the above nitrosulphurizing treatment, in order to at least include the white layer and the nitrogen diffusion in the nitrided layer formed on the member body side, the heating temperature of the reaction furnace is set higher than the normal nitriding treatment temperature. It is desirable to increase the diffusion efficiency of nitrogen and the concentration of ammonia in the reactor, which is a source of nitriding. Therefore, the heating temperature of the reactor is set to 600-
It is preferable to set the ammonia concentration in the reaction furnace to 650 ° C. and 20 to 70%.

When the cooling rate after holding at 600 to 650 ° C. is set to a rate higher than 250 ° C./Hr, the mixed layer on the surface layer of the member is peeled off. For example, 620 ° C.
11. The time required for the cooling operation to further cool to 250 ° C.
Since it takes 3 hours and is not economical, the cooling rate after the holding is in the range of 30 to 250 ° C./Hr. In addition to the ammonium sulfide solution, an ammonium sulfite-hydrate, an ammonium sulfite solution, or the like can also be used as a source of sulfurization and oxidation. The surface layer of the member or mold used during warm or hot is not porous but dense in form, has a small coefficient of friction, and has a high heat-insulating effect in terms of structure. In this case, it is important that iron sulfide contributing to the improvement of seizure resistance be present in a large amount.

On the other hand, the mold base material used for the hot mold of the present invention is SKD61, SK specified in JIS standard.
Hot tool steel having high temperature strength and toughness represented by T4 is preferable, and SKD7, S having higher high temperature strength than these are preferred.
It can be applied to KD8, high-speed steel, or their improved steels as needed.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. (Example 1) Steel having the composition shown in Table 1 was prepared, and steel 1 and steel 2 were tempered to 48HRC by quenching and tempering. Thereafter, a round bar test piece having a shape of 5 mm in diameter and 20 mm in length was prepared, and its end face was finished with a grindstone. Hot baking tests were performed on these test pieces that had been subjected to various surface treatments shown in Table 2. In the hot baking test, one end of the test piece was attached to a chuck of a drill press, rotated at 1540 rpm, and the other end of the test piece was pressed against a block made of SNCM439 heated to 600 ° C., and frictionally slid for 30 seconds. The load was 0.31 to 2.07 KN, and the seizure resistance was evaluated by defining the value obtained by dividing the pressing load at which seizure occurred by the cross-sectional area as the seizure limit surface pressure (MPa).

[0033]

[Table 1]

[0034]

[Table 2]

Table 3 shows the surface structure after various surface treatments and the test results. The seizure limit surface pressure of the member of the present invention is 102.4 or more.
It is in the range of 105.4 MPa, 3.3 times that of ion nitriding, and 1.7 to 1.8 that of salt bath sulphinitriding A.
2.7 times to 2.8 times compared to salt bath sulphonitriding B and 1.3 times compared to gas sulphonitriding with cylinder gas.
Thus, it can be seen that the members of the present invention have significantly improved seizure limit surface pressure as compared with the comparative members. In addition, when the end of the test piece after reaching the sintering limit surface pressure was cut out and observed for microstructure, each of them exhibited a re-quenched structure, and the temperature was raised to a temperature exceeding the AC ₁ transformation point of the steel. It was confirmed that a large amount of frictional heat was generated. This indicates that the member of the present invention can significantly reduce frictional heat generation.

[0036]

[Table 3]

In Table 3, the sample No. 6 and sample N
o. Sample No. 10 (each corresponds to a comparative member), 12
The cross-sectional structure of the surface of the test piece subjected to the same treatment as that of (corresponding to the member of the present invention) was observed, and a line analysis was performed using an EPMA (micro X-ray analyzer). The results are shown in FIGS. 1, 2 and 3, respectively. Show. FIG. 1 shows the results of salt bath oxynitridation A, which is out of the scope of the member of the present invention, in which the maximum concentration of S in the uppermost mixture layer of the surface treatment layer is 2.2 wt%, and sulfur and nitrogen in the mixture layer are different. Was 0.4, and the thickness of the mixture layer was 29 μm. FIG. 2 also shows the case of gas sulphonitriding with a cylinder gas which is not the object of the present invention. At 10.8, the thickness of the mixture layer was 1.2 μm. No oxygen peak could be confirmed.

On the other hand, the maximum concentration of S in the mixture layer of the surface treatment layer corresponding to the member of the present invention is 28.0 wt% as shown in FIG. 3, and the sulfur / nitrogen concentration ratio (S / N) is high. 5.
At 8, the mixture layer thickness was 12 μm. Although no oxygen peak in the mixture layer could be confirmed, the maximum concentration of oxygen in the intermediate layer was 8.8 wt%. As described above, the sample No. of the member of the present invention. The mixture layer of FIG. 12 (FIG. 3) contains iron sulfide particles and iron nitride particles without oxygen, and the S / N in the mixture layer is in the range of 0.5 <S / N <10. It can be seen that the structure and configuration of the mixture layer are different.

Next, the structures of the mixture layer and the nitride layer on the member body side will be described with reference to an optical microscope structure. Sample No. of the member of the present invention. 12 is shown in FIG. FIG. 3 shows a mixture layer having a thickness of 12 μm, an intermediate layer having a thickness of 18 μm, and a nitride layer on the member body side. The nitride layer is formed of a white layer and a nitrogen diffusion layer. 18 μm and 0.25 mm. The constituent materials of the mixture layer, the intermediate layer and the nitride layer will be described in detail in the X-ray analysis of Example 3.

(Embodiment 2) Process 5 and Process 6 shown in Table 2
After holding at 540 ° C. for 20 hours and at 600 ° C. for 5 hours, the cooling rate to 250 ° C. was increased to 35 to 500 ° C. /
Table 4 shows the results of examining film peeling of the mixture layer after the treatment in place of Hr. Process 5 causes film peeling when the cooling rate is high, whereas process 6 of the present invention requires 500 ° C.
At / Hr, the film peeled off, but at a cooling rate lower than 200 ° C./Hr, the film was sound without peeling.

[0041]

[Table 4]

Example 3 Sample Nos. Shown in Table 3 5 to Sample No. Sample No. 10 (corresponding to a comparative member) 11
From Sample No. 14 (corresponding to the member of the present invention) The cross section of the surface of the test piece subjected to the same treatment as that of the sample of the present invention was 25 μm from the surface.
The hardness was measured by applying a load of 100 g every time, and the results of measuring the maximum hardness of each were shown in Table 5. Sample No. of the member of the present invention. Sample No. 11 from The maximum hardness of 14 is 800H
V or more.

[0043]

[Table 5]

Example 4 Sample Nos. Shown in Table 3 6 and sample no. Sample No. 10 (corresponding to a comparative member) 1
FIG. 5 shows the results of X-ray analysis using the X-ray diffractometer from the outermost surface of the surface of the test piece subjected to the same treatment as in Example 2 (corresponding to the member of the present invention). The X-ray diffraction condition is Co
Applied voltage 40KV, applied current 200 using target
The diffraction angle (2θ) was measured from 30 ° to 120 ° under the condition of mA.

The sample No. shown in FIG. The results of the qualitative analysis of No. 6 were that the iron oxide was Fe ₃ O ₄ and the iron nitride was Fe ₃ N and Fe ₄ N, and no iron sulfide was detected. Sample No. of FIG. 10
The qualitative analysis results are as follows: iron sulfide is FeS, iron nitride is Fe ₃ N
And Fe ₄ N, and no iron oxide was detected. Sample No. of FIG. The qualitative analysis result of No. 12 shows that iron sulfide is Fe
S, iron oxide is Fe ₃ O ₄ and iron nitride is Fe ₃ N and Fe ₄ N
Met.

From the above, considering the result of EPMA of the mixture layer shown in Example 1 comprehensively, Sample No. Although the mixture layer of No. 6 contains a small amount of S at 2.2 wt%,
It was confirmed that it was substantially formed from Fe ₃ O ₄ and Fe ₃ N. In addition, it was confirmed that the nitrided layer on the member body side of the mixture layer was Fe ₃ N (white layer) and Fe ₄ N (nitrogen diffusion layer) when considered comprehensively with the results of an optical microscope.
Next, the sample No. The mixture layer of No. 10 contained 32.4 wt% of S.
It is a FeS monolayer substantially. Further, it was confirmed that the intermediate layer substantially contained FeS and Fe ₃ N, and the nitride layer on the member body side was Fe ₄ N (nitrogen diffusion layer). Next, the sample No. It was confirmed that the mixture layer of No. 12 did not contain Fe ₃ O _{4 and} was substantially composed of FeS and Fe ₃ N. In addition, the nitride layer on the member body side was the sample No. 11 is Fe ₃ N
(White layer) and Fe ₄ N (nitrogen diffusion layer).

Example 5 Sample Nos. Shown in Table 3 6 and sample no. 8 and sample no. Sample No. 10 (corresponding to a comparative member) The surface resistance of the test piece subjected to the same treatment as that of Sample No. 12 (corresponding to the member of the present invention) was measured from the surface with a continuous weighting type surface property measuring device to evaluate the adhesion at the interface between the mixture layer and the nitride layer, in order to evaluate the scratch resistance. Table 6 shows the results. The measurement conditions of the continuous weighting type surface property measuring machine were as follows: a diamond scratching needle of 30μ was used, and the moving speed was 0.2 mm / sec.
c, 500 g of full scale vertical load was used.

[0048]

[Table 6]

Sample No. of the member of the present invention It was confirmed that the scratch resistance of No. 12 was higher than that of the comparative member. From this, it can be said that the adhesiveness of the mixture layer of the present invention is better than that of the comparative member. Further, Sample No. was determined from the form of the surface layer. 6 and sample no. 8
Is a porous layer, whereas the sample No. of the member of the present invention is a porous layer. The mixture layer of No. 12 is in a dense form. For example, when heat stress is applied to a mold in a high-temperature forging operation, the porous and poorly adhered comparative member is a starting point or a propagation point of a heat crack caused by the porous material. However, since the member of the present invention has improved adhesion and a dense form, it can be expected to improve the life when used as a mold for warming.

Example 6 Sample No. 3 in Table 3 2,4
Hot forging dies used for ring pressure molding having 6, 8, and 12 surface layer structures were prepared. The dimensions of the mold are 148 mm in diameter and 56 mm in height. Roughening the steel of steel 2 to the approximate dimensions of the mold, quenching and tempering 48HR
After tempering to C and finishing to the above dimensions, each was subjected to a surface treatment so as to obtain a predetermined surface layer structure.
Forging uses a forging press of 1600 tons, 1200 ° C
The SCM420H workpiece heated at high frequency was forged every 14 seconds after upset processing. Table 7 shows the life of the mold.

[0051]

[Table 7]

Each of the molds reached the end of its life due to damage due to wear. It can be seen that the mold of the present invention has a mold life approximately twice as long as that of the comparative mold as compared with the comparative mold which is a conventional mold, and is excellent in wear resistance.

[0053]

As described above, in the warm member and the warm mold having the surface layer structure of the present invention, the iron sulfide mainly has the effect of suppressing the heat load due to frictional heat and the heat insulating effect. In addition, iron nitride can improve the life of the mold due to the effect of maintaining the wear resistance of the surface. Since the form of the mixture layer is dense and the adhesion of the intermediate layer between the mixture layer and the nitride layer is improved, the mixture layer is less likely to become a starting point or a propagation path of a separation layer or a crack during use. It is very effective for long-term use.

[Brief description of the drawings]

FIG. 1 shows a sample No. of a comparative member. 6 is an electron micrograph showing the structure of the mixture layer of No. 6, a line analysis chart by EPMA, and an optical microscope photograph showing the structure of the nitride layer on the member body side of the mixture layer.

FIG. 2 shows a sample No. of a comparative member. 10 is an electron micrograph showing the structure of a mixture layer of No. 10, a line analysis chart by EPMA, and an optical microscope photograph showing the structure of a nitride layer on the member body side of the mixture layer.

FIG. 3 shows a sample No. of a member of the present invention. 12 is an electron micrograph showing the structure of a mixture layer of No. 12, a line analysis chart by EPMA, and an optical microscope photograph showing the structure of a nitride layer on the member body side of the mixture layer.

FIG. 4 shows a sample No. of a comparative member. 6 and sample no. 10
And the sample No. of the member of the present invention. 12 is an X-ray diffraction diagram of FIG.

Claims (12)

[Claims] 1. A member having a mixture layer composed of iron sulfide particles and iron nitride particles on a surface layer portion thereof, wherein a weight concentration ratio (S / N) of sulfur and nitrogen in the mixture layer is 0.5 <S / N. A member for hot and warm use, wherein there is a region satisfying the expression <10. 2. A member having a mixture layer composed of iron sulfide particles and iron nitride particles on a surface layer portion thereof, wherein a weight concentration ratio (S / N) of sulfur to nitrogen in the mixture layer is 0.5 <S / N. A member for warm / hot use, wherein a region satisfying the expression <10 is present, and at least a nitride layer is formed on the member body side of the mixture layer. 3. A member having a mixture layer composed of iron sulfide particles and iron nitride particles on a surface layer portion thereof, wherein a weight concentration ratio (S / N) of sulfur to nitrogen in the mixture layer is 0.5 <S / N. A member for warm / hot use, having a region satisfying the expression <10 and having an intermediate layer made of iron sulfide, iron nitride and iron oxide on the member main body side of the mixture layer. 4. A member having a mixture layer composed of iron sulfide particles and iron nitride particles on a surface layer portion thereof, wherein the weight concentration ratio of sulfur to nitrogen (S / N) in said mixture layer is 0.5 <S / N. <10, and an intermediate layer composed of iron sulfide, iron nitride, and iron oxide on the member body side of the mixture layer, and at least a nitride layer on the member body side of the intermediate layer. A hot / hot member characterized by being formed. 5. A member having a mixture layer composed of iron sulfide particles and iron nitride particles on a surface layer portion thereof, wherein a weight concentration ratio (S / N) of sulfur to nitrogen in the mixture layer is 0.5 <S / N. There is a region satisfying the expression <10, and an intermediate layer made of iron sulfide, iron nitride and iron oxide is formed between the mixture layer and the nitride layer formed on the member body side, and the nitride layer is A warm / hot member comprising a white layer and a nitrogen diffusion layer. 6. A hot / warm member in which the concentration of S in the mixture layer according to claim 1 is 5 to 35% by weight. 7. The member for hot and warm use according to claim 3, wherein the concentration of S in the intermediate layer is 1 to 10 by weight%. 8. A hot / hot member wherein the thickness of the mixture layer according to claim 1 is 0.1 to 20 μm. 9. A warm / hot member according to claim 3, wherein the intermediate layer is a dense layer having a thickness of 0.1 to 40 μm. 10. A member for warm and warm use, wherein the nitrided layer according to claim 2 has a maximum hardness of 800 HV or more. 11. A colorless ammonium sulfide solution and a yellow ammonium sulfide solution are placed in a gas generating vessel at a ratio of 6: 1 to 1: 1.
The hydrogen sulfide gas concentration is 100 to 600 ppm and the ammonia gas concentration is 0.1 to 1.0% in the mixed gas of the on-liquid level gas generated and the carrier gas composed of argon or nitrogen gas. The member for hot and hot is arranged and introduced into the reactor heated to 600 to 650 ° C., and the ammonia concentration in the reactor is adjusted to 20 by argon or nitrogen gas and ammonia gas supplied from another container. A method for producing a member for hot and warm use, wherein the temperature is adjusted to 70% and the cooling rate after holding at 600 to 650 ° C is gradually cooled to 30 to 250 ° C / Hr, followed by gas sulphonitriding. 12. A hot working mold comprising the hot working member according to any one of claims 1 to 11.