JPH08120394A - Production of highly rigid material - Google Patents

Abstract

PURPOSE: To provide the highly rigid material of large Young's modulus by achieving the reaction heat treatment in the prescribed atmosphere prior to the forming of the powder of Fe-Al ferritic steel and diffusing the grains in fine state. CONSTITUTION: After the powder of Fe-Al ferritic steel is formed including the extrusion of the extrusion ratio of at least 3, the secondary recrystallizing heat treatment is achieved to obtain the highly rigid material of at least one kind. Prior to this forming, at least one kind of easily oxidizing element or Al is contained in the powder to achieve the heat treatment in the oxidizing atmosphere. Alternatively, at least one kind of easily nitrizing element or Al is contained in the powder to achieve the heat treatment in the nitrizing atmosphere. Again alternatively, at least one kind of easily carbonizing element or Al is contained in the powder to achieve the heat treatment in the carbonizing atmosphere. Oxide, nitride and carbide of each added element are precipitated in the process of the reaction heat treatment to form the diffused condition of fine oxide, nitride and carbide of 5-50nm in grain size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material, particularly a high-rigidity composite material used as a structural member requiring excellent rigidity in the technical field of automobiles, aircraft, rockets, industrial machines, robots and the like. Hereinafter, simply referred to as a high rigidity material).

[0002]

2. Description of the Related Art In recent years, high-rigidity materials have been demanded. For example, in automobile materials, lightweight and downsized materials for the purpose of improving fuel economy and damping materials for improving the riding comfort have been developed. The need is growing.

If a high-rigidity material is used to reduce the weight, the high-rigidity material can reduce the amount of strain such as bending due to an external force, and the size of the component can be reduced accordingly. On the other hand, by using a high-rigidity material as the damping material, it is possible to reduce the vibration caused by the strain of the material by using a small amount of material.

Therefore, as will be clear from now on,
Not only for automobile parts but also for all structural members,
Expectations are gathering for high-rigidity materials that can absorb a large amount of strain with a small shape.

As a method for developing such a material, it has been attempted to improve the rigidity by adding an alloying element to Fe, forming a ceramic particle dispersion composite in an alloy matrix, or forming a texture by rolling.

However, regarding the addition of alloy elements, in the case of Fe-based alloys, even the addition of the Re element, which has the largest improvement rate, only improved the Young's modulus by about 21,000 to 22,000 kgf / mm ² . Further, when the ceramic particles are dispersed in the alloy matrix, a sufficient improvement in rigidity can be obtained by increasing the mixing ratio of the ceramic particles.
The reduction in toughness and strength is unavoidable, and only 24,000 kgf / mm ² can be obtained as a practical material at most by the rolling method for forming a texture.

On the other hand, for steel materials, a method of increasing rigidity is realized by aligning crystal orientations having a high Young's modulus in a specific direction by thermomechanical processing, that is, by integrating them. That is, it is a material design and process design aiming at integration of the {111} planes of ferritic steel having a body-centered cubic lattice. JP-A-56-23223 and JP-A-59
See −83721 publication.

However, as disclosed in the above publication, conventionally, after cold rolling with a working rate of 5 to 10% or more, tempering or winding at a temperature of 720 to 900 ° C. or less is conventionally used. Even if the crystal orientations are accumulated in a certain direction, the Young's modulus is at most 23,000 to 24,000 kgf / mm ²
It was nothing more than a degree.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made various investigations to develop a material having higher rigidity. The reason is that the conventional method only slightly improves the Young's modulus by the thermomechanical treatment method. Shows that the degree of integration of {111} planes in ferritic steel is at most 15-
It is because it is as small as 20 times, and I have learned that this is because the processing strain introduced in the processing process and its accumulation are small.

Therefore, as a result of various studies in order to find a method capable of imparting high work strain, a large amount of lattice strain is introduced and accumulated when strong work is applied to a material in which particles are finely dispersed in a metal matrix. However, since the dispersed particles have a dislocation pinning effect, the introduced lattice strain remains without being released by residual heat after hot working. This lattice strain energy serves as a recrystallization driving force for forming a <111> texture at the time of heat treatment after processing. Further, during this recrystallization heat treatment, the finely dispersed particles have the effect of pinning the grain boundary movement, and thus have the effect of raising the recrystallization temperature. In such a material having a high recrystallization temperature, recrystallization is rapidly started to some extent when the temperature is increased by heating, and as a result, the recrystallized grains have directionality and the X-ray intensity is 30 times or more that of the equiaxed material. Form a significant <111> texture.

It is already known that such fine particle dispersion can obtain a high Young's modulus of 29,000 kgf / mm ² through the accumulation of strain during strong working and the contribution to directional secondary recrystallization during heat treatment. Wishhei 4-58271, Dohei 5-220122
Patent applications have been filed as No. 5, No. 5-220123 and No. 5-220124.

That is, according to the findings, the finely dispersed particles exert a dislocation pinning effect during the forming process, accumulate a large amount of lattice strain in the material, and greatly contribute to the subsequent texture formation.

Japanese Patent Application Nos. 4-58271 and 5-220122
As a method for finely dispersing particles in a high-rigidity material according to the invention disclosed in No. 5, 5-220123, and No. 5-220124, ceramic particles are mainly added to a raw material metal powder or alloy powder. A method of obtaining a fine dispersion state by mechanical alloying treatment (mechanical alloying, the same applies below) is used.

However, as a result of subsequent research and development, in this method, when the grain size of the ceramic particles to be added is as coarse as 0.10 μm, if the workability in the forming process is small, sufficient lattice strain is not introduced and accumulated, It was found that the subsequent formation of texture could not be performed sufficiently and high rigidity could not be obtained.

That is, in this method, when it is desired to reduce the workability, the ceramic particles to be added must be fine, for example, 0.05 μm or less, to the extent that sufficient strain can be introduced at the time of molding even with the low workability. Here, the case where the workability is desired to be low is, for example, the case where the extrusion ratio is kept low to obtain a large-diameter rod material.

However, in order to obtain such a sufficiently fine structure, it is necessary to carry out further fine structure such as mechanical alloying for a long time, which causes a problem such as a decrease in manufacturing efficiency. Not a valid solution.

Here, the object of the present invention is to develop a more effective technique for reducing the size of dispersed particles in the method of producing a high-rigidity material by introducing a processing strain by dispersing fine particles and forming a texture. is there. More specifically, an object of the present invention is to provide a cheaper method for producing a highly rigid material having a Young's modulus of more than 25,000 kgf / mm ² .

[0018]

Here, the present inventors
As a result of various studies to achieve the above-mentioned object, oxides, nitrides, and carbides were generated by the oxidation reaction, nitriding reaction, and carbonization reaction of the elements in the powder with the atmospheric gas, and these were used as the above-mentioned finely dispersed particles. It was found that a fine dispersed state can be obtained by doing so, and the present invention was completed.

That is, the present invention is a method of subjecting a powder of a Fe-Al-based ferritic steel composition to a molding process including at least an extrusion process with an extrusion ratio of 3 or more, and then performing a secondary recrystallization heat treatment. A method for producing a high-rigidity material characterized by performing reactive heat treatment prior to processing, and finely dispersing particles by at least one of the following (1), (2) and (3) during the reactive heat treatment. is there.

(1) The powder contains at least one oxidizable element or Al, and the powder is heat-treated in an oxidizing atmosphere. (2) The powder is at least one nitridable element or Al
And heat treating the powder in a nitriding atmosphere. (3) The powder is at least one kind of easily carbonizable element or Al
And heat treating the powder in a carbonizing atmosphere.

Further, the present invention is a method of performing secondary recrystallization heat treatment after subjecting a powder of Fe-Si type ferritic steel composition to at least an extrusion process with an extrusion ratio of 3 or more, and performing a secondary recrystallization heat treatment. A method for producing a high-rigidity material characterized by performing reactive heat treatment prior to processing, and finely dispersing particles by at least one of the following (1), (2) and (3) during the reactive heat treatment. is there.

(1) The powder contains at least one oxidizable element or Si, and the powder is heat-treated in an oxidizing atmosphere. (2) The powder is at least one nitridable element or Si
And heat treating the powder in a nitriding atmosphere. (3) The powder is at least one kind of easily carbonizable element or Si
And heat treating the powder in a carbonizing atmosphere.

Here, the above "Fe-Al type ferritic steel",
The "Fe-Si based ferritic steel" includes not only the case of 100% by volume ferritic phase but also the stainless steel having austenite phase up to about 5% by volume. The presence of at least 95% by volume of ferrite phase is sufficient for increasing the rigidity. The easily oxidizable element, easily nitridable element, and easily carbonizable element mean an element having a tendency to oxidize, nitride, or carbonize more easily than Fe, Al or Si.

Specifically, as the easily oxidizable element, Fe-
For Al-based ferritic steels, for example, Zr, Ti, Mg, Be, Hf, T
h, Y, and rare earth elements are included. For Fe-Si ferritic steel, for example, Zr, Ti, Al, B, Mg, Nb, V, Ta,
Be, Hf, Th, Y and rare earth elements are included.

Examples of easily nitridable elements include Zr, Ti, Th, Hf, Be, Y, and rare earth elements in Fe-Al type ferritic steel. For Fe-Si ferritic steel, Zr, T
It contains i, Al, B, Mg, Nb, V, Ta, Th, Hf, Be, Y and rare earth elements. Examples of the easily carbonizable element include Zr, Ti, Ta, V, Nb, Y and H in Fe-Al ferrite steel.
f, Mn, W, Mo, B, Be, Si and rare earth elements are included.

These easily oxidizable elements, easily nitridable elements, and easily carbonizable elements react with oxygen, nitrogen and carbon in the atmosphere gas in the course of the reaction heat treatment, so that oxides, nitrides and carbides are finely divided. It is presumed that it precipitates and forms a dispersed state of fine oxides, nitrides, and carbides having a particle size of about 5 to 50 nm.

For example, when Ti is contained in the powder, the average particle size of TiN produced by the heat treatment for nitriding reaction is about 10 nm, which is much higher than that when TiN particles (average particle size 60 nm) are added by mechanical alloying. A fine and good dispersion state can be obtained.

The action of the reaction heat treatment is as follows.
It is to react with oxygen, nitrogen, and carbon in the atmospheric gas to generate oxide particles, nitride particles, and carbide particles, and to precipitate them as finely dispersed particles, which is not limited.

Here, according to one embodiment of the present invention, a Fe—Al-based ferritic steel composition or Fe—Si-based composition containing the above-mentioned easily oxidizable element, easily nitridable element and easily carbonizable element as a starting material. A powder of ferritic steel composition (either a single alloy powder or a powder mixture) is used.
In this case, what is finely dispersed is oxide particles, nitride particles, and carbide particles of easily oxidizable, easily nitridable, and easily carbonizable elements depending on the atmosphere during the reaction heat treatment.

According to another aspect of the present invention, the above-mentioned easily oxidizable element, easily nitridable element, and easily carbonizable element are not contained.
You may use the powder of Fe-Al type ferritic steel composition and Fe-Si type ferritic steel composition. In this case, the fine dispersion is
Depending on the atmosphere during the reaction heat treatment, Fe-Al ferrite steel, Al oxide particles, Al nitride particles, Al carbide particles, in the Fe-Si ferrite steel, Si oxide particles, Si nitride particles, Si carbide particles.

[0031]

Next, the effect of finely dispersing particles in the ferritic alloy steel matrix of the present invention on increasing the rigidity of the material will be described as follows. That is,
A large amount of lattice strain is introduced and accumulated when strong processing is applied to a material in which particles are finely dispersed in a metal matrix, but since dispersed particles have a dislocation pinning effect, they are introduced in the residual heat after hot working. Lattice strain remains without being released. This lattice strain energy serves as a recrystallization driving force for forming a <111> texture at the time of heat treatment after processing. Further, during this recrystallization heat treatment, the finely dispersed particles have the effect of pinning the grain boundary movement, and thus have the effect of raising the recrystallization temperature. In such a material having a high recrystallization temperature, recrystallization is rapidly started at a certain temperature during heating and heating, and as a result, the recrystallization has directionality and is 30% higher than that of an isotropic polycrystal in terms of X-ray intensity. Not less than doubled <111>
Form a texture.

As described above, the fine particle dispersion has the effect of increasing the rigidity of the material by accumulating strain during strong working and contributing to directional secondary recrystallization during heat treatment. In order for the dispersed particles to exert the dislocation and grain boundary pinning effect, it is necessary to form a dispersed state in which the interparticle distance is smaller due to fine dispersion. From another aspect, the present invention provides means for that purpose. To provide.

The reason why reaction heat treatment is used as a method for dispersing oxides, nitrides, and carbides in the present invention is that when this method is used, oxides, nitrides,
This is because a finer dispersed state can be obtained as compared with the case where carbide particles are added as a raw material for mechanical alloying. That is, in the former case, a finely dispersed state is obtained by generating a large number of nuclei of oxides, nitrides, and carbides in the metal matrix during the reaction heat treatment, whereas mechanical alloying maintains the particle size of the added particles. Therefore, it is difficult to obtain a dispersed state finer than the particle diameter of the added particles. For this reason, the former method is superior to the latter method.

The reason for limiting the alloying elements for forming oxides, nitrides and carbides in the present invention is as follows.

In the case of Fe-Al type ferritic steel, the alloy elements for forming oxides, nitrides and carbides are limited to easily oxidizable elements, easily nitridable elements, easily carbonizable elements or Al. Element is the main element that constitutes ferritic steel
Fe, Al or more in the case of easily oxidizable elements, easily nitridable elements, and easily carbonizable elements than oxides, nitrides, and carbides of Fe
Oxides, nitrides, carbides more stable oxides, nitrides,
This is because carbides are easily generated, and therefore fine dispersion states of oxides, nitrides, and carbides can be obtained by controlling the addition amount, heat treatment atmosphere, temperature, and time.

Further, in the case of Fe-Si type ferritic steel, the alloy elements for forming oxides, nitrides and carbides are limited to easily oxidizable elements, easily nitridable elements, easily carbonizable elements or Si. These elements are more important than the oxides, nitrides, and carbides of Fe, which are the main elements that make up ferritic steel, or
In the case of easily oxidizable elements, easily nitridable elements, and easily carbonizable elements
Fe, Si oxides, nitrides, and carbides are more stable than oxides, nitrides, and carbides. Therefore, fine oxides, nitrides, and carbides can be obtained by controlling the addition amount, heat treatment atmosphere, temperature, and time. This is because the dispersed state of is obtained.

That is, <111> for obtaining high rigidity
Preferred oxides, nitrides to obtain recrystallized texture,
In order to form a finely dispersed state of carbide, an oxide,
Reactants for forming nitrides and carbides must have the property of forming oxides, nitrides, and carbides more easily than Fe, Al, and Si, and assuming that, the addition amount, heat treatment atmosphere, temperature, and time control This is because it is possible to control the distributed state by.

Of course, in the case of using Fe-Al type ferritic steel containing no easily oxidizable, easily nitridable and easily carburizable elements, Al oxides, nitrides and carbides are formed, and easily oxidized. Properties, easily nitriding, when using Fe-Si ferritic steel containing no easily carburizing elements Si oxide, nitride,
It is also possible to generate a carbide and use the resulting fine dispersion.

As described above, as the easily oxidizable element for forming the oxide, in the case of Fe-Al type ferritic steel,
It is desirable to use one or more of Zr, Ti, Mg, Be, Hf, Th, Y, and rare earth elements. Also,
In the case of Fe-Si based ferritic steel, Zr, Ti, Al, B, Mg,
It is desirable to use one or more of Nb, V, Ta, Be, Hf, Th, Y and rare earth elements. Oxidation of these additional elements produces respective oxides.As such oxides, ZrO ₂ , TiO ₂ ,
It is desirable that the oxide or the composite oxide is one or more of Al ₂ O ₃ , B ₂ O ₅ , MgO, NbO, V ₂ O ₅ and Y ₂ O ₃ . As the composite oxide, for example, Y _x Al _y O, Ti _x Y _y O
, Al _x Ti _y O are effective.

As described above as the easily nitridable element for forming the nitride, in the case of Fe-Al type ferritic steel,
It is desirable to use one or more of Zr, Ti, Th, Hf, Be, Y, and rare earth elements. In the case of Fe-Si ferrite steel, Zr, Ti, Al, B, Mg, Nb, V, T
It is desirable to use one or more of a, Th, Hf, Be, Y and rare earth elements. By nitriding these additive elements, respective nitrides are produced,
Such nitrides include ZrN, TiN, AlN, BN, Mg
Desirably, it is a nitride or a composite nitride of one or more of ₃ N ₂ , NbN, VN, TaN, and YN.

As already described as the easily carbonizable element for forming carbide, in the Fe--Al type ferritic steel, Zr,
It is desirable to use one or more of Ti, Ta, V, Nb, Y, Hf, Mn, W, Mo, B, Be, Si and rare earth elements. In Fe-Si ferritic steel, Zr, Ti, T
It is desirable to use one or more of a, V, Nb, Y, Hf, Mn, W, Mo, B, Be and rare earth elements. Carbides of these additional elements produce respective carbides, and as such carbides,
Desirably, it is a carbide or a composite carbide of one or more of ZrC, TiC, TaC, Al ₄ C ₃ , VC, NbC, and Y ₂ C ₃ .

Further, these oxides, nitrides, and carbides may be in a mixed or mixed state thereof, or may be in a mixed or mixed state with boride or the like. The compounding amounts of these easily oxidizable elements, easily nitridable elements, and easily carbonizable elements are not particularly limited and can be appropriately set according to the purpose, but the metal element is preferably 1.0 to 5.0%.

It can be said that the reaction formation of oxides, nitrides and carbides is a reaction between the atmospheric gas and the surface of the powder. Since the reaction state is controlled by the reaction time and the powder particle size, there is no particular limitation on the raw material powder particle size, but since it is easy to achieve uniform particle dispersion by a short time treatment, it is preferably 1000 microns or less,
Further, it is more preferable that the thickness is 250 microns or less.

Of course, there is no limitation on the method for producing the raw material powder, and it is possible to use crushed powder from ingot, atomized powder, PR
EP (Plasma Rotating Electrode Process) powder or the like is used. By using such powder, fine particles are dispersed on the surface and inside of the powder particles by oxidation, nitriding, and carbonization from the atmospheric gas.

Specifically, in the case of oxidation, it is controlled by oxygen partial pressure (PO ₂ ), H ₂ / H ₂ O and CO / CO _{2 in} the atmosphere gas.
PO ₂ control is very difficult. For example, in Fe-Al-based ferritic steel, for example, when oxidation is performed at 800 to 1100 ° C., in order to oxidize only easily oxidizable elements such as Zr and Mg without oxidizing Fe and Al, 10 ^{− It} is difficult to control the oxygen partial pressure below ^40, which is difficult. In Fe-Si-based ferrite steel, for example, when attempting to oxidation at 800 C. to 1100 ° C., Fe, Ti without oxidizing the Si, in order to only oxidize oxidizable elements such as Al is 10 ^-30 It is difficult to control the oxygen partial pressure below, which is difficult.

On the other hand, control by H ₂ / H ₂ O is relatively easy. This control of H ₂ / H ₂ O is controlled by the dew point of the hydrogen gas atmosphere. In the case of Fe-Al ferritic steel, a dew point of about 40 ° C or lower is sufficient to oxidize easily oxidizable elements such as Al and Zr and Mg without oxidizing Fe.
In order to oxidize easily oxidizable elements such as Zr and Mg without oxidizing Al, dry hydrogen gas having a high purity of −70 ° C. or lower may be used.

In the case of Fe-Si type ferritic steel, a dew point of about 40 ° C. or lower is sufficient to oxidize easily oxidizable elements such as Si and Ti and Al without oxidizing Fe.
In order to oxidize easily oxidizable elements such as Ti and Al without oxidizing e and Si, dry hydrogen gas having a high purity of −70 ° C. or lower may be used. In the case of CO / CO ₂ , the ratio is 1/3 ~
10 ^6/1 about the control is sufficient.

The reaction temperature and time are not particularly limited, but the extent that the powders do not sinter and solidify, that is, 800
It is preferably about 1100 ° C for about 15 to 100 minutes. The atmosphere for the nitride formation reaction is not particularly limited as long as it is a gas containing nitrogen such as N ₂ gas, ammonia gas, and N ₂ + H ₂ gas, but it is difficult to control when the reaction is performed at a high temperature as compared with the oxidation reaction. , 500-80
It is desirable to perform a long-time treatment at a low temperature of about 0 ° C. for 2 to 10 hours.

The atmosphere for the reaction for forming the carbide is a gas containing C, for example, CO + CO ₂ gas (in the case of CO + CO ₂ atmosphere,
Oxide is formed, then carbide is formed, and is formed as a mixture), alcohol-added atmosphere gas, methane gas, RX
Gas is effective. The easiest control method is by carbon potential (CP) using RX gas. Generally, a short time of about 0.2 to 0.5, 800 to 1100 ° C, and about 10 to 60 minutes is preferable, which is slightly lower than CP used for carburizing control of steel materials.

Further, in the case of oxide formation, it is desirable to carry out a reduction treatment because oxidation (surface oxidation etc.) more than desired progresses in many cases. Further, since these reactions are a reaction between the particle surface and the atmospheric gas, it is desirable to react in a fluidized bed and a laminated state of 30 mm or less.

Then, the finely dispersed single alloy powder or powder mixture of the oxides, nitrides, and carbides according to the present invention is subjected to extrusion molding, for example, hot extrusion to obtain a state in which lattice strain is accumulated. Material is obtained. As the molding method at this time, after molding by HIP, CIP, etc.,
The lattice distortion may be introduced by performing hot extrusion processing and performing strong processing before and after the rolling and / or forging.

In the case of the present invention, a high-rigidity material can be obtained even if the workability represented by the extrusion ratio is relatively small.
May be 10. Generally, this extrusion ratio is 10 or more. By heat-treating the material thus obtained, a highly rigid material having a significantly developed <111> texture can be obtained. The heat treatment temperature at this time is for the secondary directional recrystallization treatment.
Heat treatment for 0.5 to 2 hours is sufficient. Next, the operation of the present invention will be described more specifically with reference to examples.

[0053]

【Example】

(1) In case of finely dispersing oxides Fe-4Al based ferritic steel as a base Ti, Zr, Mg, Y
Ar gas atomized powder (250 μm or less) added with a predetermined amount of Al, etc., and Ar gas atomized powder (250 μm or less) with a predetermined amount of Ti, Zr, Al, Y, etc. added based on Fe-3Si ferritic steel. H ₂ gas (dew point 20 ° C,
Oxidation heat treatment was performed at −80 ° C.) and CO / CO ₂ (10 ⁵ ) at 900 ° C. for 30 minutes. The powder oxidized with H ₂ gas having a dew point of 20 ° C. was further subjected to reduction heat treatment at 1000 ° C. for 60 minutes using H ₂ gas at a dew point of −80 ° C.

This powder was preheated to 1100 ° C. for 1 hour, and then hot-worked at 1050 ° C. at an extrusion ratio of 10 to form a strong work. Then, secondary recrystallization heat treatment was performed at 1250 ° C. for 1 hour to obtain a material. With respect to the material thus obtained, the oxide particles produced were identified for their average particle diameter and particle species by an analytical electron microscope, and Young's modulus was measured by the longitudinal resonance method.

The results are shown in Table 1 together with the comparative examples. As is clear from the results shown in Table 1, H ₂ / H ₂ O, CO / CO ₂ was used as the reaction heat treatment atmosphere for the oxide dispersion.
It turns out that is effective.

In the case of Fe-4Al type ferritic steel, the elements contained in the powder are Ti, Zr, Mg, Y, which are more easily oxidized than Al.
It is also clear that elements such as Al are effective, and in the case of Fe-3Si based ferritic steel, elements such as Ti, Zr, Al, Y and Si that are more easily oxidized than Si are effective.

[0057]

[Table 1]

(2) Fine Dispersion of Nitride Based on Fe-4Al ferritic steel, a predetermined amount of elements such as Ti, Zr and Y are added to the ingot / pulverized powder (-500
(μm or less) in an atmosphere of NH ₃ , N ₂ + H ₂ , NH ₃ + Ar
The reaction heat treatment was performed at 600 ° C. for 7 hours.

Further, using an ingot / crushed powder (-500 μm or less) containing Fe-3Si type ferritic steel as a base and adding a predetermined amount of elements such as Ti, Nb, Al and Y, NH ₃ ,
The reaction heat treatment was performed at 600 ° C. for 7 hours in an atmosphere of N ₂ + H ₂ and NH ₃ + Ar.

Using these powders, after preheating at 1100 ° C. for 1 hour, they were subjected to strong extrusion molding at 1050 ° C. by hot extrusion at an extrusion ratio of 10. Then, secondary recrystallization heat treatment was performed at 1250 ° C. for 1 hour to obtain a material.

With respect to the thus-obtained material, the produced nitride particles were identified for their average particle diameter and particle species by an analytical electron microscope, and Young's modulus was measured by the longitudinal resonance method. These results are summarized in Table 2 together with Comparative Examples.

As is clear from the results shown in Table 2, N ₂ + H ₂ and N ₂ were used as the reaction heat treatment atmosphere for dispersing the nitride.
It is understood that any of H ₃ is effective, and that a mixture of these gases and an inert gas may be used.

As for the elements contained in the powder, in the case of Fe-4Al type ferritic steel, elements such as Ti, Zr, Y and Al which are more easily nitrided than Al are effective, and the elements of Fe-3Si type ferritic steel are In this case, it is clear that elements such as Ti, Nb, Al, Y and Si that are more easily nitrided than Si are effective.

[0064]

[Table 2]

(3) When Carbide is Finely Dispersed Fe-4Al and Fe-3Si based ferritic steels as a base
Using Ar atomized powder (250 μm or less) containing a predetermined amount of elements such as i, Nb, Zr and V, RX gas (CP = 0.
4, 0.5), Ar + CH ₄ , Ar + CH ₃ OH at 950 ° C for 30 minutes.

These powders were preheated to 1100 ° C. for 1 hour and then subjected to hot working at 1050 ° C. by hot extrusion at an extrusion ratio of 10. Then, secondary recrystallization heat treatment was performed at 1200 ° C. for 1 hour to obtain a material.

With respect to the thus-obtained material, the generated carbide particles were identified for their average particle diameter and particle species by an analytical electron microscope, and Young's modulus was measured by the longitudinal resonance method. These results are collectively shown in Table 3 together with Comparative Examples. As is clear from the results shown in Table 3, the reaction heat treatment atmosphere for dispersing the carbide is RX gas, Ar + C.
It can be seen that H ₄ and Ar + CH ₃ OH are effective.

In the case of Fe-4Al ferritic steel, the elements contained in the powder are Ti, Nb, Zr, V, which are more easily carbonized than Al.
Elements such as Al are effective, and in the case of Fe-3Si ferrite steel, Ti, Nb, Zr, V, which are more easily carbonized than Si,
It is also clear that elements such as Si are effective.

[0069]

[Table 3]

[0070]

EFFECTS OF THE INVENTION According to the present invention, a large amount of processing strain can be imparted, and the <111> degree of integration can be significantly improved. As a result, it becomes possible to manufacture high-rigidity materials with a Young's modulus of 25,000 kgf / mm ² or more, and it can be applied to various spring materials, various shaft materials, and various structural parts including automobiles that require vibration absorption. .

Claims (2)

[Claims] 1. A method of performing secondary recrystallization heat treatment after subjecting a powder of Fe-Al-based ferritic steel composition to a shaping process including at least an extrusion process with an extrusion ratio of 3 or more, prior to the shaping process. A method for producing a high-rigidity material, characterized in that a reactive heat treatment is performed, and during the reactive heat treatment, particles are finely dispersed by at least one of the following means (1), (2) and (3). (1) The powder is at least one oxidizable element or Al
And heat treating the powder in an oxidizing atmosphere. (2) The powder is at least one nitridable element or Al
And heat treating the powder in a nitriding atmosphere. (3) The powder is at least one kind of easily carbonizable element or Al
And heat treating the powder in a carbonizing atmosphere. 2. A method of performing secondary recrystallization heat treatment after subjecting a powder of Fe—Si based ferritic steel composition to a shaping process including an extrusion process of at least an extrusion ratio of 3 or more, prior to the shaping process. A method for producing a high-rigidity material, characterized in that a reaction heat treatment is performed, and during the reaction heat treatment, particles are finely dispersed by at least one of the following means (1), (2) and (3). (1) The powder is at least one oxidizable element or Si
And heat treating the powder in an oxidizing atmosphere. (2) The powder is at least one nitridable element or Si
And heat treating the powder in a nitriding atmosphere. (3) The powder is at least one kind of easily carbonizable element or Si
And heat treating the powder in a carbonizing atmosphere.