JP2005281768A - Nanocrystal white cast iron powder having high hardness, tough nanocrystal white cast iron bulk material having high hardness and high strength and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily produce a tough nanocrystal white cast iron bulk material having high hardness and high strength by producing a tough nanocrystal white cast iron powder material having extremely high hardness and compacting the powders. <P>SOLUTION: The nanocrystal white cast iron powder having high hardness is composed of an aggregate of white cast iron nanocrystal particles and comprises 2.3 to 3.5 mass% carbon, and in which reinforcing substance for a ferrite phase in the nanocrystals is dispersed and precipitated. The tough nanocrystal white cast iron bulk material having high hardness and high strength is obtained by compacting the many nanocrystal white cast iron powders. A white cast iron forming component material comprising 2.2 to 3.5 mass% carbon is subjected to mechanical milling (MM) or mechanical alloying (MA) to produce a high hardness nanocrystal white cast iron powder composed of an aggregate of white cast iron nanocrystal particles, and, from the powders, a tough nanocrystal white cast iron bulk material having high hardness and high strength is produced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high hardness nanocrystalline white cast iron powder, in particular, a dispersion / precipitation strengthened nanocrystalline white cast iron powder, a bulk material, and a manufacturing method thereof.

The strength and hardness of the metal material increase as the crystal grain size d becomes smaller, as shown by the Hall Petch relational expression, and such a relation is similarly established until d is in the vicinity of several tens of nm. Making the diameter ultrafine to the nano-size level has become one of the most important means for strengthening metal materials. This is particularly important as a method for strengthening steel materials. In steel materials, when hard materials such as carbides are dispersed or precipitated in the microstructure thus obtained, the strength characteristics can be further improved.
However, research on nanocrystallization has not yet been made on white cast iron, which is extremely important as a practical material. Normally, in white cast iron materials, carbon, which is a component of the same material, exists as carbides in the form of flakes or needles at the micron size level, and the strength is extremely low and the elongation is almost zero. Is limited.

  However, the crystal grain size d of many metallic materials including white cast iron manufactured by the melting method is usually several microns to several hundred microns, and it is difficult to make d nano-order by post-processing, for example, Even in the case of controlled rolling, which is important as a process for refining the grain size of steel, the lower limit of the grain size that can be reached is about 4 to 5 μm. Therefore, such a normal method cannot obtain a material having a particle size reduced to the nano size.

The present invention solves the above-described problems and is the following invention.
The present invention basically includes (1) each material of white cast iron constituent components, (2) molten white cast iron material, or (3) other elements or alloys thereof in (1) and (2) Nano-size of ultra-high hardness and ultra-fine hardness of the crystal grain size by mechanical alloying (MA) or mechanical milling (MM) treatment using a ball mill etc. A nanocrystalline powder of white cast iron composition with strength (high strength), hardness (ultra-hard) and toughness that is close to its limit, which can be achieved by dispersion and precipitation of special carbides and carbonitrides, etc. The object of the present invention is to provide a nanocrystalline white cast iron bulk material that retains the properties of the powder by solidification molding of the crystal white cast iron powder in the hot state or solidification molding in the superplastic temperature range.

That is, the present invention is a powder material and bulk material of nanocrystalline white cast iron having high hardness, high strength and toughness having the following constitution, and a method for producing both materials.
[1] A white cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and the nanocrystals in the ferrite phase as a reinforcing substance of the ferrite phase. Selected from metric size (1-10 nm) granular or spherical (1) metal or metalloid carbide, (2) metal or metalloid nitride, or (3) metal or metalloid carbonitride A high-hardness nanocrystalline white cast iron powder obtained by dispersing and precipitating one or more substances.
[2] The metal or metalloid constituting the carbide, nitride or carbonitride described in [1] is iron, chromium, vanadium, titanium, zirconium, molybdenum, niobium, tantalum, tungsten, nickel, cobalt, aluminum High hardness nanocrystalline white cast iron powder characterized by comprising any one or more selected from silicon and boron. In addition, when these alloy elements are one, the density | concentration contains 0.1-40 mass% of white cast iron powder, and when there are two or more alloy elements, the total density | concentration is white cast iron powder. You may contain 0.1-45 mass%.

[3] The carbide, nitride or carbonitride described in [1] above is a high melting point element such as chromium, vanadium, titanium, zirconium, molybdenum, niobium, tantalum, or tungsten contained in white cast iron, It is formed in the case of a high concentration content of 0.5 to 10% by mass, and these are present in a single state and / or coexisting with other carbides, nitrides or carbonitrides. High hardness nanocrystalline white cast iron powder.
That is, for example, in the case of chromium (Cr), molybdenum (Mo), vanadium (V), and tungsten (W), carbides generated at each concentration are approximately as follows.
Cr: 1.5% or less: Fe ₃ C, (Fe, Cr) ₃ C,
1.5-3%: (Fe, Cr) ₃ C,
3-7%: Cr ₇ C ₃ ,
Mo ... 1% or less: Fe ₃ C, (Fe, Mo) ₃ C,
1-3%: (Fe, Mo) ₃ C,
3 to 7%: Mo ₂ C, M ₆ C [M: Fe, Mo]
V: 0.5% or less: Fe ₃ C, (Fe, V) ₃ C,
0.5 to 0.6%: (Fe, V) ₃ C,
0.6 to ₃ %: V ₄ C ₃
W: 4% or less: Fe ₃ C, (Fe, W) ₃ C,
4-6%: (Fe, W) ₃ C,
6 to 10%: W ₂ C, M ₆ C [M: Fe, W]
However, for example, when W, Cr, V, etc. coexist, an extremely hard special carbide having a Vickers hardness Hv of 1000 or more such as (Fe, Cr, W, V) ₆ C is generated (cementite). Hv value of (Fe ₃ C): 850)

[4] Any one of [1] to [3] above, wherein the white cast iron powder comprising an aggregate of white cast iron nanocrystal particles contains 0.01 to 5.0 mass% of nitrogen. 2. High hardness nanocrystalline white cast iron powder according to item 1.
[5] The high-hardness nanostructure according to any one of [1] to [3], wherein the white cast iron powder made of an aggregate of white cast iron nanocrystal particles is free of nitrogen. Crystal white cast iron powder.
[6] White cast iron powder composed of aggregates of white cast iron nanocrystal particles is used as a dispersion / precipitation strengthening substance and / or a grain growth inhibitor (1) chromium, vanadium, titanium, zirconium, molybdenum, niobium, tantalum, Any one or more selected from tungsten, nickel, cobalt, aluminum, silicon, or boron, or (2) any one or more of carbides, nitrides, and carbonitrides of the respective elements are present. The high-hardness nanocrystalline white cast iron powder according to any one of [1] to [5] above.

[7] A white cast iron powder containing 2.2 to 3.5% by mass of carbon composed of an aggregate of white cast iron nanocrystal particles, and between and / or inside the nanocrystal particles, A high-hardness nanocrystalline white cast iron powder characterized by containing a metal or metalloid carbide as a crystal grain growth inhibitor.
[8] White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and between and / or inside the nanocrystal particles, A high-hardness nanocrystalline white cast iron powder comprising a metal or metalloid oxide as a crystal grain growth inhibitor.
[9] White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and between and / or inside the nanocrystal particles, A high-hardness nanocrystalline white cast iron powder comprising a metal or metalloid nitride as a crystal grain growth inhibitor.
[10] White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and between and / or inside the nanocrystal particles, A high-hardness nanocrystalline white cast iron powder comprising a metal or metalloid carbonitride as a crystal grain growth inhibiting substance.

[11] A white cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and between and / or inside the nanocrystal particles, A high-hardness nanocrystalline white cast iron powder comprising a metal or metalloid silicide (silicide) as a crystal grain growth inhibitor.
[12] White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and between and / or inside the nanocrystal particles, A high-hardness nanocrystalline white cast iron powder comprising a boride of a metal or a semimetal as a crystal grain growth inhibitor.
[13] A white cast iron powder containing 2.2 to 3.5% by mass of carbon composed of an aggregate of white cast iron nanocrystal particles, and between and / or inside the nanocrystal particles, (1) Metal or metalloid carbide, (2) Metal or metalloid oxide, (3) Metal or metalloid nitride, (4) Metal or metalloid carbonitride And (5) a metal or metalloid silicide (silicide) or (6) a metal or metalloid boride (boride), wherein two or more selected from (1) to (6) are present. High hardness nanocrystalline white cast iron powder.

[14] White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of white cast iron nanocrystal particles or aggregates thereof contains 0.005 to 1.0% by mass of oxygen in the form of a metal oxide The high-hardness nanocrystalline white cast iron powder according to any one of [1] to [13] above, wherein
[15] In order to prevent denitrification in the solidification process of the aggregate of white cast iron nanocrystal particles, a metal element having a higher chemical affinity with nitrogen than iron in the nanocrystal white cast iron is included. The high-hardness nanocrystalline white cast iron powder according to any one of [1] to [14] above.
[16] White cast iron nanocrystal particles were obtained by mechanically milling (MM) or mechanical alloying (MA) a material of a white cast iron forming component in the form of a lump, piece, granule or powder using a ball mill or the like. The high-hardness nanocrystalline white cast iron powder according to any one of [1] to [15] above, which is a product.
[17] White cast iron nanocrystalline particles are made of lump, flake, granular or powdery ordinary carbon steel, alloy steel, white cast iron, gray cast iron, mottle cast iron, spheroidal graphite cast iron, alloy cast iron, other alloy elements or alloys It is obtained by mechanical milling (MM) or mechanical alloying (MA) of a constituent material of white cast iron selected from any one or more materials using a ball mill or the like. The high-hardness nanocrystalline white cast iron powder according to any one of [1] to [15] above.

[18] In the mechanical alloying (MA) or mechanical milling (MM) process, the mechanical energy input is adjusted by selecting the mass ratio of the grinding media used for the ball mill and the raw material powder and / or the operation energy of the ball mill, etc. (1) Particle size of carbide, nitride, or carbonitride as a ferrite particle or dispersion / precipitate in the aggregate of nanocrystal particles, (2) Formation of these dispersion / precipitate, or (3 (1) A high hardness nanocrystalline white as set forth in any one of [1] to [17] above, wherein one or more selected from (1) to (3) is controlled. Cast iron powder.
[19] Nanocrystalline particle assembly obtained by mechanical alloying (MA) or mechanical milling (MM) of white cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystalline particles As a substance for promoting atomic bonding in the solidification process between bodies (powder) or a substance for suppressing or preventing delayed fracture of the solidified body (bulk material), 0.01 to 5.0% by mass of titanium or zirconium is contained. The high-hardness nanocrystalline white cast iron powder according to any one of [1] to [18] above, wherein
[20] A high-hardness, high-strength, tough nanocrystalline white cast iron, comprising a large number of nanocrystalline white cast iron powders according to any one of [1] to [19] Bulk material.

[21] Lumped, flake, granular or powdery white cast iron forming component material containing 2.2 to 3.5% by mass of carbon is mechanically milled (MM) or mechanically alloyed (MA) using a ball mill or the like. A method for producing a high hardness nanocrystalline white cast iron powder comprising obtaining a high hardness nanocrystalline white cast iron powder comprising an aggregate of white cast iron nanocrystal particles.
[22] A lump, flake, granule, or powdery white cast iron forming component material containing 2.2 to 3.5% by mass of carbon is lump, flake, granule, or powder ordinary carbon steel, alloy steel, The item [21] above, characterized in that it is selected from one or more of white cast iron, gray cast iron, mottle cast iron, spheroidal graphite cast iron, alloy cast iron, other alloy elements or alloys Of high hardness nanocrystalline white cast iron powder.
[23] In the mechanical alloying (MA) or mechanical milling (MM) process, the mechanical energy input is adjusted by selecting the mass ratio of the grinding media used for the ball mill and the raw material powder and / or the operation energy of the ball mill, etc. (1) Particle size of carbide, nitride, or carbonitride as a ferrite particle or dispersion / precipitate in the aggregate of nanocrystal particles, (2) Formation of these dispersion / precipitate, or (3 1) The production amount of the high-hardness nanocrystalline white cast iron powder according to any one of [21] or [22] above, wherein one or more selected from (1) to (3) is controlled Manufacturing method.

[24] Lumped, flake, granular or powdery white cast iron forming component materials containing 2.2 to 3.5% by mass of carbon, such as chromium, vanadium, titanium, zirconium, molybdenum, niobium, tantalum, tungsten By adding 0.5 to 10% by mass or more of a high melting point element and mechanically milling (MM) or mechanical alloying (MA), the white cast iron nanocrystal particles or aggregates thereof are in a single state and The method for producing high-hardness nanocrystalline white cast iron powder according to any one of [21] to [23] above, which is / is present in a coexisting state with other carbides, nitrides or carbonitrides .
[25] Dispersion / precipitation of carbide, nitride or carbonitride containing refractory element as a basic composition in the parent ferrite phase alone and / or coexisting with other carbide, nitride or carbonitride In addition to adjusting the concentration of each refractory element, the mechanical energy in the mechanical alloying (MA) or mechanical milling (MM) process and / or the temperature and time of MA and MM are effective. The method for producing ultra-high hardness nanocrystalline white cast iron powder according to any one of [21] to [24] above, wherein
[26] In hot solidification molding of nanocrystalline white cast iron powder by the method described in any one of [21] to [25] above, (1) solidification molding temperature, (2) solidification molding time, (3) By controlling any one or more selected from (1) to (4) of solidification pressure or (4) heat treatment such as annealing after solidification, carbide, nitride or carbonitride A method for producing a nano-crystalline white cast iron bulk material having high hardness, high strength and toughness, characterized by effectively dispersing and precipitating a material.

[27] The powder of white cast iron nanocrystal particles according to any one of [16] to [19] above, spark plasma sintering at a temperature of 500 ° C. to 900 ° C., hot pressing, Nano carbides and nano nitrides by vacuum hot solidification molding such as sheath rolling, hot forging, extrusion molding, hot isostatic pressing (HIP) or explosive solidification Alternatively, a method for producing a nanocrystalline white cast iron bulk material having high hardness, high strength and toughness, characterized in that it becomes a dispersion / precipitation strengthened nanocrystalline white cast iron bulk material of any one or more of nano carbonitrides.
[28] The powder of white cast iron nanocrystal particles according to any one of [16] to [19] above, discharge plasma sintering, hot pressing, sheath rolling, extrusion molding in a temperature range showing superplasticity, By performing vacuum hot solidification molding (superplastic solidification molding) such as hot forging and hot isostatic pressing (HIP), any one or more of nano carbide, nano nitride or nano carbonitride A high-hardness, high-strength, tough nanocrystalline white cast iron bulk material, characterized in that it becomes a dispersion-reinforced nanocrystalline white cast iron bulk material with the above compound.
[29] The powder of white cast iron nanocrystal particles according to any one of [16] to [19] above is subjected to spark plasma sintering at a temperature of 500 ° C. to 900 ° C., hot pressing, extrusion molding, hot Solidification processing is performed by vacuum hot solidification molding such as forging, hot isostatic pressing (HIP), rolling, or explosion molding to form a nanocrystalline white cast iron bulk material, and then the white cast iron bulk material is superplastic. A method for producing a bulk material of nanocrystalline white cast iron having high hardness, high strength and toughness, characterized by being formed in a temperature range of

[30] The atmosphere in which mechanical milling or mechanical alloying is performed is any one selected from (1) an inert gas such as argon gas, (2) N ₂ gas, or (3) NH ₃ gas, or (4 The high hardness, high strength and toughness according to any one of [21] to [29] above, which is an atmosphere of two or more mixed gases selected from (1) to (3) Manufacturing method of nanocrystalline white cast iron bulk material.
[31] Any one of [21] to [29] above, wherein the atmosphere for mechanical milling or mechanical alloying is a gas atmosphere to which a reducing substance such as a slight amount of H ₂ gas is added. A method for producing a nanocrystalline white cast iron bulk material having high hardness, high strength and toughness as described in 1.
[32] The above items [21] to [29], wherein the atmosphere for performing mechanical milling or mechanical alloying is a vacuum or a reducing atmosphere in which a reducing substance such as a slight amount of H ₂ gas is added to the vacuum. ] The manufacturing method of the nanocrystal white cast iron bulk material with high hardness, high strength, and toughness according to any one of the above.
[33] The compound composition of nanocrystalline white cast iron contains 0 to 40% by mass of other elements, and the temperature of solidification molding is 20 above and below the eutectoid temperature (about 730 ° C.) of cast iron. The method for producing a high hardness, high strength and tough nanocrystalline white cast iron bulk material according to any one of [21] to [32] above, wherein the temperature is within a range of%.

According to the present invention, the ferrite particles of the parent phase can be obtained by subjecting a material such as an elemental mixed substance of the white cast iron material or a molten white cast iron to mechanical alloying (MA) or mechanical milling (MM). In addition to being ultrafine to nanosize, finer nanosized carbides and carbonitrides are dispersed and precipitated as granular or spherical particles in the same ferrite phase. Strengthening by grain refinement at the level and dispersion / precipitation of carbides, carbonitrides, etc. can be realized.
Further, according to the present invention, an increase in the amount of chromium in the starting material of MA or MM or addition of a high melting point element such as molybdenum, vanadium, or tungsten to the raw material causes iron carbide (cementite) in the ferrite grains of the parent phase. ) From the state in which these high melting point elements are dissolved (generation of double carbides) to the state where ultra-hard special carbides and nitrides based on chromium, vanadium, etc. are dispersed or precipitated as nano-sized ultrafine grains By doing so, a nanocrystalline white cast iron powder material with extremely high hardness and toughness can be obtained, and by solidifying and molding the powder, it is strong and strong with high hardness and high strength. Nanocrystalline white cast iron bulk material can be easily manufactured.
Further, in the nanocrystalline white cast iron material, superplasticity is manifested by appropriate selection of the size and composition of the crystal grains, and this phenomenon can be effectively applied to the solidification molding process of MA powder.

Normally, in white cast iron material, carbon, which is a component of the same material, is present in the form of micron-sized flakes or needle-like carbides, but when mechanical alloying is used for such white cast iron material, A very tough powder in which nano-sized granular or spherical carbides are dispersed in the iron matrix (the nanocrystalline ferrite phase) is obtained. When this is solidified, the ferrite phase is added to the powder having the above characteristics. Due to the synergistic effect of ultra-miniaturization down to nano-size and dispersion of nano-sized carbides close to a sphere in the same ferrite phase, it is possible to produce materials with extremely excellent strength characteristics that cannot be produced by conventional melting methods.
In other words, in white cast iron materials, when alloying elements with high melting points such as chromium and vanadium are added, solid solution strengthening of these nanosized ferrite phases with these alloying elements and dispersion / precipitation of higher hardness special carbides and carbonitrides This makes it possible to produce a more excellent nanocrystalline white cast iron material having extremely high hardness, high strength and toughness.
On the other hand, when the crystal grain size is reduced to the nano-size level, many metal materials exhibit a unique phenomenon called superplasticity in a temperature range of 0.5 Tm (Tm: melting point (K)) or higher. . By utilizing this phenomenon, even a white cast iron material molded body having a relatively complicated shape can be manufactured without undergoing a melting process.

  The present invention basically performs mechanical alloying (MA) or mechanical milling (MM) treatment on a material such as a mixed material of nanocrystalline white cast iron forming material or a molten white cast iron powder material using a ball mill or the like. Thus, an ultra-hard and tough nanocrystalline white cast iron powder material can be provided. And by adopting a method using the solidification processing of the powder, or superplasticity in the molding process, the strength close to its limit that can be achieved when the crystal grain size is refined to the nano-size level ( It is possible to provide a dispersion / precipitation strengthened type white cast iron bulk material such as nano carbide / nano carbonitride having high strength) to hardness (ultra-hard) and corrosion resistance.

Further, in the present invention, elemental powders of simple metals such as iron, carbon, chromium, molybdenum, vanadium, or a mixed material of white cast iron forming components obtained by adding other elements to these simple metal powders or melted white cast iron powders When the material is subjected to mechanical alloying (MA) or mechanical milling (MM) treatment at room temperature in an atmosphere of argon gas or the like using a ball mill or the like, the MM or MA-treated powder is added by the ball mill. By virtue of the mechanical energy, the Vickers hardness of white cast iron that is easily refined to a crystal grain size of about 10 to 30 nm, for example, to a grain size of about 25 nm, is about 800 to 1000.
Then, such MM and MA-treated powder is vacuum-sealed in a stainless steel tube (sheath) having an inner diameter of about 10 mm, and solidified by sheath rolling using a rolling mill at a temperature of around 700 to 750 ° C. In the case of cast iron, a sheet having a thickness of about 1.5 mm and having a yield strength of about 1.2 GPa or more can be easily manufactured.

Also, mechanical alloying (MA) using a ball mill or the like to mixed powder obtained by adding about 2 to 5% by mass of other elements such as molybdenum and vanadium to elemental mixed powder of white cast iron components such as iron, chromium and carbon. ), The refinement in the MA process is further promoted, and the crystal grain size is on the order of several nanometers.
In addition, oxygen up to about 0.5% by mass that is inevitably mixed in the mechanical alloying (MA) or mechanical milling (MM) -treated powder described in the preceding paragraph in the course of MA or MM treatment is usually in the form of a metal oxide. It exists and suppresses grain coarsening in the solidification molding process due to the pinning effect of the grain boundary by the oxide. In order to enhance such suppression effect, it is more preferable to add 1 to 10% by volume, particularly 3 to 5% by volume, of a particle dispersant such as AlN or NbN to the MA or MM treated powder.

Further, in the present invention, in mechanical alloying (MA) or mechanical milling (MM) treatment of elemental powder material of white cast iron forming material or melted white cast iron, chromium, molybdenum to be added to and contained in the material, When the concentration of refractory elements such as vanadium and tungsten is increased, nanosized ultra-hard double carbides / nitrides or special carbides / nitrides based on the refractory elements are dispersed and precipitated in the ferrite phase of the nanocrystals. Can be easily manufactured, and then solidified molding such as sheath rolling and extrusion can be used to effectively produce high hardness, high strength and tough nanocrystalline white cast iron bulk material. It can be carried out.
As a result, nanostructures such as Fe _91.8 C ₃ Cr ₅ N _0.2 (mass%), Fe _56.8 C ₃ Cr ₃₅ Mo ₃ V ₂ N _0.2 (mass%), Fe _58.8 C ₃ Cr ₃₅ W ₃ N _0.2 (mass%), etc. A powder material of crystalline white cast iron and its bulk material are obtained.

表１によると、各試料の固化過程は、常温におけるその硬さ、結晶粒径の値から判断して６５０℃以上の温度（超塑性開始温度Ｔｓｐ以上の温度）からより効果的になることが解る。 Examples of the present invention will be described below.
Example 1:
Solidification molding utilizing superplasticity was performed on a mechanically alloyed (MA) -treated powder having a carbon content of 2.2 to 3.5% by mass and having a white cast iron composition. One example will be described below.
Alloy powder of Fe _94.3 C _3.5 Cr ₂ N _0.2 (mass%) composition by mechanical alloying (MA) from mixed powder of elemental powder of iron, carbon and chromium and iron nitride (containing nitrogen: 8.51 mass%) The powder was loaded into a graphite die having an inner diameter of 40 mm, and a temporary sintered body having a diameter of 40 mm and a thickness of 5 mm was obtained by hot pressing for 15 minutes at 700 ° C. in a vacuum at a molding pressure of 60 MPa. .
Next, each molding temperature of the solidified molded body obtained by applying a compressive load for 30 minutes at a strain rate of 10 ⁻³ / s in the thickness direction of the sintered body at each temperature of 550, 600, 650, 700, and 750 ° C. Table 1 shows the average crystal grain size d, the Vickers hardness Hv, the tensile strength σ _B , the elongation δ, and the oxygen / nitrogen analysis values at T.

According to Table 1, the solidification process of each sample can be more effective from a temperature of 650 ° C. or higher (temperature of superplasticity starting temperature Tsp or higher) as judged from its hardness and crystal grain size at normal temperature. I understand.

＊[メカニカルアロイング（ＭＡ）処理したＦｅ_84.9-XＣ_XＣｒ₁₅Ｎ_0.1（質量％）（Ｘ＝２．２〜３．５）白鋳鉄粉末及び同粉末に、放電プラズマ焼結（真空７００℃）＋圧延（真空７００℃）を施して得た固化成形体試料の平均結晶粒径ｄ及びビッカース硬さＨｖ] Example 2:
A mixed powder of elemental powder of iron, carbon and chromium and iron nitride (containing nitrogen: 8.51% by mass) was subjected to mechanical alloying (MA) (atmosphere: argon gas / MA time: ₂₀₀ h) to obtain Fe _{84.9- X} C _X Cr ₁₅ N _0.1 (wt%) (X = 2.2~3.5) made a white iron alloy powder.
Next, these alloy powders were loaded into a graphite die having an inner diameter of 40 mm, and were subjected to discharge plasma sintering in vacuum at a temperature of 700 ° C. above the superplasticity start temperature Tsp at a strain rate of 10 ⁻³ / s and a holding time of 5 minutes ( SPS), hot rolling was further applied at the same temperature, and this was water-cooled to obtain a solidified molded body. Table 2 shows the average crystal grain size d and Vickers hardness Hv of the white cast iron solidified compact and the white cast iron powder sample.
As can be seen from Table 2, according to the present invention, considerable crystal grain growth was observed during the solidification molding process, but the nanostructure was retained after molding. It can be seen that the Vickers hardness Hv indicates a hardness higher than that of a hardened material having a martensitic structure of high carbon steel.

* [Mechanical alloying (MA) -treated Fe _84.9-X C _X Cr ₁₅ N _0.1 (mass%) (X = 2.2 to 3.5) Spark plasma sintering (vacuum 700) ° C) + rolling (vacuum 700 ° C), average crystal grain size d and Vickers hardness Hv of solidified molded body sample]

＊[メカニカルアロイング（ＭＡ）処理後、放電プラズマ焼結（真空７００℃）＋圧延（真空７００℃）を施したＦｅ_82-yＣ₃Ｃｒ₁₅Ｎ_y（質量％）（ｙ＝０〜０．５）白鋳鉄固化成形体試料の平均結晶粒径ｄ及びビッカース硬さＨｖ] Example 3:
By the same method as in Example 2,
A mixed powder of elemental powder of iron, chromium and carbon and iron nitride (containing nitrogen: 8.51 mass%) is subjected to mechanical alloying (MA) using a ball mill (atmosphere: argon gas / MA time: 200 h). Thus, an Fe _82-y C ₃ Cr ₁₅ N _y (mass%) (y = 0 to 0.5) alloy powder was prepared.
Next, these alloy powders were loaded into a graphite die having an inner diameter of 40 mm under the same conditions as in Example 2 and subjected to discharge plasma sintering (SPS) at 700 ° C. in vacuum, and then to the same temperature. Table 3 shows the average crystal grain size d and the Vickers hardness Hv of the solidified molding material obtained by further hot rolling and water-cooling it.
As seen from Example 3 and Table 3, according to the present invention, the Vickers hardness Hv of the solidified molded body of the Fe _82-y C ₃ Cr ₁₅ N _y (mass%) white cast iron sample is Fe _{84.9-X of} Example 2. As in the case of the C _X Cr ₁₅ N _0.1 (mass%) sample, an extremely high value is obtained, and it can be seen that the value of the Vickers hardness Hv increases with the content of nitrogen N.

* [Fe _82-y C ₃ Cr ₁₅ N _y (mass%) (y = 0 to 0) subjected to discharge plasma sintering (vacuum 700 ° C.) + Rolling (vacuum 700 ° C.) after mechanical alloying (MA) treatment .5) Average crystal grain size d and Vickers hardness Hv of white cast iron solidified compact sample]

＊[（ａ）Ｆｅ₈₂Ｃ₃Ｃｒ₁₅（質量％）白鋳鉄の各形成成分の元素状混合物質、（ｂ）溶製した前記組成の白鋳鉄材料、及び（ｃ）前記組成となるように調合した白鋳鉄、鋼、鉄、炭素及びクロムの混合物質、の各出発原料からメカニカルアロイング（ＭＡ）又はメカニカルミリング（ＭＭ）処理して得た前記組成の合金粉末の放電プラズマ焼結（真空７００℃）＋圧延（真空７００℃）による白鋳鉄固化成形体試料の平均結晶粒径ｄ、ビッカース硬さＨｖ、引張強さσ_B及び伸びδ] Example 4:
Targeting a cast iron composition material of Fe ₈₂ C ₃ Cr ₁₅ (mass%), (a) an elemental mixed material of forming components of the cast iron material, which is a starting material without addition of nitrogen N, (b) melted Cast alloy material having the above composition, and (c) mechanical alloying (MA) or mechanical milling (MM) using a ball mill for a mixed material of cast iron, steel, iron, carbon, and chromium prepared to have the above composition (Atmosphere: Argon gas / MA or MM treatment time: 200 h) By performing the treatment, three types of white cast iron alloy powders having the same composition were obtained.
Next, these three kinds of alloy powders were loaded into a graphite die having an inner diameter of 40 mm under the same conditions as in Example 3 and subjected to discharge plasma sintering (SPS) at 700 ° C. in a vacuum. Table 4 shows the average crystal grain size d, Vickers hardness Hv, tensile strength σ _B , and elongation δ of the solidified molding material obtained by further hot-rolling at a temperature and subjecting it to water cooling treatment. .
In view of Table 4, according to the present invention, there is a significant difference between the mechanical properties such as crystal grain size and tensile strength of these white cast iron solidified bodies obtained from different starting materials as described above. I understand that it is not allowed.

* [(A) Fe ₈₂ C ₃ Cr ₁₅ (mass%) elemental mixed material of each forming component of white cast iron, (b) molten white cast iron material of the above composition, and (c) so as to be the above composition Spark plasma sintering (vacuum) of alloy powder of the above composition obtained by mechanical alloying (MA) or mechanical milling (MM) treatment from each of the prepared white cast iron, steel, iron, carbon and chromium mixed materials 700 ° C.) + Average crystal grain size d, Vickers hardness Hv, tensile strength σ _B and elongation δ of solid cast iron samples by rolling (vacuum 700 ° C.)]

＊[（ａ）Ｆｅ_81.9Ｃ₃Ｃｒ₁₅Ｎ_0.1（質量％）白鋳鉄各形成成分の元素状物質と窒化鉄（含有Ｎ：８．５１質量％）との混合物質、（ｂ）溶製した前記組成の白鋳鉄材料、及び（ｃ）前記組成となるように調合した白鋳鉄、鋼、鉄、炭素、クロム及び窒化鉄（含有Ｎ：８．５１質量％）の混合物質、の各出発原料からメカニカルアロイング（ＭＡ）又はメカニカルミリング（ＭＭ）処理して得た前記組成の合金粉末の放電プラズマ焼結（真空７００℃）＋圧延（真空７００℃）による白鋳鉄固化成形体試料の平均結晶粒径ｄ、ビッカース硬さＨｖ、引張強さσ_B及び伸びδ] Example 5:
Fe _81.9 C ₃ Cr ₁₅ N _0.1 (mass%) for cast iron composition material, (a) Elemental substance and iron nitride (containing N: 8.51 mass) which is a starting material and is a constituent of the cast iron material %)), (B) cast iron material having the above-described composition, and (c) cast iron, steel, iron, iron nitride (containing N: 8.51% by mass) prepared to have the above-mentioned composition, and By applying mechanical alloying (MA) or mechanical milling (MM) (atmosphere: argon gas / MA or MM treatment time: 200 hours) using a ball mill to the chromium mixed material, three types of the same composition are used. White cast iron alloy powder was obtained.
Next, after each of these three types of alloy powders was subjected to spark plasma sintering (SPS) under the same conditions as in Example 4, it was further subjected to hot rolling at 700 ° C. and subjected to water cooling treatment. Table 5 shows the average crystal grain size d, Vickers hardness Hv, tensile strength σ _B , and elongation δ of the solidified molding material obtained as described above.
As can be seen from Table 5, according to the present invention, as in Example 4, the mechanical properties such as crystal grain size and tensile strength of these white cast iron solidified bodies obtained from the different starting materials as described above. It can be seen that there is no significant difference between the three samples and that the strength characteristics of the three samples are greatly improved by containing nitrogen N in all three samples.

* [(A) Fe _81.9 C ₃ Cr ₁₅ N _0.1 (mass%) White cast iron mixed material of elemental material of each forming component and iron nitride (containing N: 8.51 mass%), (b) melted Each starting material of white cast iron material having the above composition, and (c) a mixed material of white cast iron, steel, iron, carbon, chromium and iron nitride (containing N: 8.51% by mass) prepared to have the above composition Average crystal of white cast iron solidified compact sample by discharge plasma sintering (vacuum 700 ° C.) + Rolling (vacuum 700 ° C.) of alloy powder of the above composition obtained by mechanical alloying (MA) or mechanical milling (MM) treatment from Particle size d, Vickers hardness Hv, tensile strength σ _B and elongation δ]

＊[対象とする試料の各形成成分の元素状粉末と窒化鉄（含有Ｎ：８．５１質量％）との混合物質から得た次の（ａ）〜（ｆ）組成のメカニカルアロイング（ＭＡ）処理合金粉末の放電プラズマ焼結（真空７００℃）＋圧延（真空７００℃）による白鋳鉄固化成形体の平均結晶粒径ｄ、ビッカース硬さＨｖ、引張強さσ_B及び伸びδ
（ａ）Ｆｅ_91.8Ｃ₃Ｃｒ₅Ｎ_0.2、（ｂ）Ｆｅ_81.8Ｃ₃Ｃｒ₁₅Ｎ_0.2、（ｃ）Ｆｅ_61.8Ｃ₃Ｃｒ₃₂Ｎｉ₃Ｎ_0.2、（ｄ）Ｆｅ_56.8Ｃ₃Ｃｒ₃₅Ｍｏ₃Ｖ₂Ｎ_0.2、（ｅ）Ｆｅ_60.8Ｃ_3.5Ｃｒ₃₅Ｔｉ_0.5Ｎ_0.2及び（ｆ）Ｆｅ_58.8Ｃ₃Ｃｒ₃₅Ｗ₃Ｎ_0.2（質量％）]

表６より、白鋳鉄固化成形体の引張強さ等の強度特性は、クロム濃度の増加とモリブデン、タングステン、チタンなどの高融点元素の存在により著しく向上することが明らかである。
表６からみて、本発明によれば、クロム量の増加、又は前記、高融点元素の添加により、鉄の炭化物（セメンタイト）へのこれらの合金元素が溶解した状態（複炭化物の生成）からクロムなどをベースにした極めて硬い特殊炭化物・窒化物等をナノサイズの極微細粒として分散ないし析出した状態にすることによって極めて高強度で強靱なナノ結晶白鋳鉄バルク材を製造できることが解る。 Example 6:
Mechanical alloying (MA) using a ball mill (atmosphere: argon) from a mixed powder of elemental powder of iron, carbon, chromium, molybdenum, vanadium, titanium or tungsten and iron nitride (containing nitrogen: 8.51 mass%) (A) Fe _91.8 C ₃ Cr ₅ N _0.2 , (b) Fe _81.8 C ₃ Cr ₁₅ N _0.2 , (c) Fe _61.8 C ₃ Cr ₃₂ Ni ₃ N _0.2 (D) Fe _56.8 C ₃ Cr ₃₅ Mo ₃ V ₂ N _0.2 , (e) Fe _60.8 C _3.5 Cr ₃₅ Ti _0.5 N _0.2 and (f) Fe _58.8 C ₃ Cr ₃₅ W ₃ N _0.2 (mass%) Cast iron alloy powder was made.
Subsequently, these alloy powders were loaded into a graphite die having an inner diameter of 40 mm under the same conditions as in Example 3 and subjected to discharge plasma sintering (SPS) at 700 ° C. in a vacuum, and then at the same temperature. Table 6 shows the average crystal grain size d, Vickers hardness Hv, tensile strength σ _B and elongation δ of the solidified molded sample obtained by further hot rolling and water cooling.

* [Mechanical alloying (MA) having the following compositions (a) to (f) obtained from a mixed material of elemental powder of each forming component of the target sample and iron nitride (containing N: 8.51% by mass) ) Average crystal grain size d, Vickers hardness Hv, tensile strength σ _B and elongation δ of white cast iron solidified body by spark plasma sintering (vacuum 700 ° C.) + Rolling (vacuum 700 ° C.) of the treated alloy powder
(A) Fe _91.8 C ₃ Cr ₅ N _0.2 , (b) Fe _81.8 C ₃ Cr ₁₅ N _0.2 , (c) Fe _61.8 C ₃ Cr ₃₂ Ni ₃ N _0.2 , (d) Fe _56.8 C ₃ Cr ₃₅ Mo ₃ V ₂ N _0.2 , (e) Fe _60.8 C _3.5 Cr ₃₅ Ti _0.5 N _0.2 and (f) Fe _58.8 C ₃ Cr ₃₅ W ₃ N _0.2 (mass%)]

From Table 6, it is clear that the strength characteristics such as tensile strength of the white cast iron solidified body are remarkably improved by the increase in the chromium concentration and the presence of refractory elements such as molybdenum, tungsten, and titanium.
As seen from Table 6, according to the present invention, chromium is increased from the state in which these alloy elements are dissolved in iron carbide (cementite) by the increase in the amount of chromium or the addition of the high melting point element (generation of double carbide). It is understood that a very strong and tough nanocrystalline white cast iron bulk material can be produced by dispersing or precipitating extremely hard special carbides / nitrides and the like based on the above as nano-sized ultrafine grains.

＊[各成分元素の元素状粉末と窒化鉄（含有Ｎ：８．５１質量％）との混合物質から得たメカニカルアロイング（ＭＡ）処理によって得られた、Ｆｅ_81.9Ｃ₃Ｃｒ₁₅Ｎ_0.1（質量％）合金粉末の次（ａ）〜（ｄ）の熱間固化成形（真空７００℃）による白鋳鉄固化成形体の平均結晶粒径ｄ、ビッカース硬さＨｖ、引張強さσ_B及び伸びδ
（ａ）圧延、（ｂ）熱間等方圧加圧焼結（ＨＩＰ）、（ｃ）押出し、（ｄ）鍛造]
表７からみて、本発明によれば、通常形状のバルク材であれば、固化成形温度などの成形条件の適切な選定により、前記合金粉末材料を鍛造などの１プロセスの固化成形処理により、極めて優れた強度特性をもつ炭化物ないし炭窒化物の分散・析出強化型のナノ結晶鋳鉄バルク材となすことができることが解る。 Example 7:
From a mixed powder of elemental powder of iron, chromium and carbon and iron nitride (containing nitrogen: 8.51 mass%), mechanical alloying (MA) using a ball mill (atmosphere: argon gas / MA treatment time: 200 h) Thus, an alloy powder of Fe _81.9 C ₃ Cr ₁₅ N _0.1 (mass%) having a cast iron composition was prepared.
The alloy powder is then heated in a vacuum at a temperature of 750 ° C. (a) rolling, (b) hot isostatic pressing (HIP), (c) extrusion, or (d) hot solidification by forging. Table 7 shows the average crystal grain size d, Vickers hardness Hv, tensile strength σ _B, and elongation δ of the solidified molded body obtained by adding a molding process and water-cooling.

* [Fe _81.9 C ₃ Cr ₁₅ N _0.1 (obtained by mechanical alloying (MA) treatment obtained from a mixed material of elemental powder of each component element and iron nitride (containing N: 8.51 mass%)) (Mass%) The average crystal grain size d, Vickers hardness Hv, tensile strength σ _B, and elongation δ of the white cast iron solidified body formed by hot solidification (vacuum 700 ° C.) of the following (a) to (d) of the alloy powder.
(A) rolling, (b) hot isostatic pressing (HIP), (c) extrusion, (d) forging]
According to the present invention, according to the present invention, according to the present invention, if the bulk material has a normal shape, the alloy powder material can be obtained by one-step solidification processing such as forging by appropriately selecting molding conditions such as solidification molding temperature. It can be seen that it can be a nanocrystalline cast iron bulk material of carbide / carbonitride dispersion / precipitation strengthening type with excellent strength characteristics.

The nanocrystalline white cast iron bulk material obtained in the present invention is suitably used for the following applications.
(1) Bearings,
When the nanocrystalline white cast iron bulk material according to the present invention is used for the rotating part of the bearing, the amount of use can be greatly reduced due to the above-mentioned strength characteristics. The power consumption during the bearing operation can be greatly reduced through a large decrease in the centrifugal force of the rolling element portion.
(2) Gears One of the metal materials often used for gear materials is a contradictory property that the surface part (tooth surface part) has wear resistance and the inside has strong toughness. In this case, it requires a highly advanced technique combining carburizing of the tooth surface and quenching / tempering, and requires a skilled surface hardening treatment. When a nanocrystalline white cast iron bulk material having ultra-hard and tough properties produced by processing is used for this, such treatment as surface hardening is unnecessary.
(3) Hot working tools and extrusion tools For example, in the case of quenching and tempering materials such as molybdenum-based high-speed steel, which is often used as high-temperature cutting tool materials, the matrix is unstable in the temperature rising range. Since it consists of a tempered martensite phase, it has the property of softening rapidly at temperatures above 400 ° C. However, the nanocrystalline white cast iron bulk material according to the present invention does not show rapid softening in such a temperature range because the matrix itself is composed of a stable phase, so it is used as a better tool material for hot working. be able to.
In addition, the nanocrystalline white cast iron bulk material according to the present invention is composed of a thermally relatively stable matrix as described above, so that it can be used more effectively for an extrusion tool that undergoes a large thermal change during use. .
(4) Medical instruments, etc. Unlike chromium-nickel austenitic stainless steel containing nickel, it does not cause diseases such as dermatitis in the human body, and scalpels used by surgeons, medical cryogenic instruments, and other general-purpose instruments. It is also promising as a material for knives and tools.

Claims (33)

A white cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, wherein the ferrite phase of the nanocrystal has a nanometer size ( 1 or 2 selected from (1) metal or metalloid carbide, (2) metal or metalloid nitride, or (3) metal or metalloid carbonitride. A high-hardness nanocrystalline white cast iron powder obtained by dispersing and precipitating the above substances.   The metal or semimetal constituting the carbide, nitride or carbonitride according to claim 1 is iron, chromium, vanadium, titanium, zirconium, molybdenum, niobium, tantalum, tungsten, nickel, cobalt, aluminum, silicon or boron. A high-hardness nanocrystalline white cast iron powder characterized by comprising at least one selected from the group consisting of:   The carbide, nitride or carbonitride according to claim 1 is a high melting point element such as chromium, vanadium, titanium, zirconium, molybdenum, niobium, tantalum, tungsten contained in white cast iron. Formed in the case of high concentration content of -10% by mass or more, and these are present in a single state and / or coexisting with other carbides, nitrides or carbonitrides Nanocrystalline white cast iron powder with hardness.   The white cast iron powder comprising an aggregate of white cast iron nanocrystal particles contains 0.01 to 5.0% by mass of nitrogen, according to any one of claims 1 to 3. Nanocrystalline white cast iron powder with hardness.   The high-hardness nanocrystalline white cast iron powder according to any one of claims 1 to 3, wherein the white cast iron powder made of an aggregate of white cast iron nanocrystal particles is a non-nitrogen-added powder.   White cast iron powder composed of aggregates of white cast iron nanocrystal particles is used as a dispersion / precipitation strengthening substance and / or a grain growth inhibiting substance. (1) Chromium, vanadium, titanium, zirconium, molybdenum, niobium, tantalum, tungsten, nickel Any one or more selected from cobalt, aluminum, silicon, or boron, or (2) any one or more of carbides, nitrides, and carbonitrides of the respective elements are present. Item 6. The high hardness nanocrystalline white cast iron powder according to any one of Items 1-5.   White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and crystal grain growth between and / or inside the nanocrystal particles A high-hardness nanocrystalline white cast iron powder comprising a metal or metalloid carbide as an inhibitor.   White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and crystal grain growth between and / or inside the nanocrystal particles A high-hardness nanocrystalline white cast iron powder comprising a metal or metalloid oxide as an inhibitor.   White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and crystal grain growth between and / or inside the nanocrystal particles A high-hardness nanocrystalline white cast iron powder characterized by containing a metal or metalloid nitride as an inhibitor.   White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and crystal grain growth between and / or inside the nanocrystal particles A high-hardness nanocrystalline white cast iron powder comprising a metal or semi-metal carbonitride as an inhibitor.   White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and crystal grain growth between and / or inside the nanocrystal particles A high-hardness nanocrystalline white cast iron powder comprising a metal or metalloid silicide (silicide) as an inhibitor.   White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and crystal grain growth between and / or inside the nanocrystal particles A high-hardness nanocrystalline white cast iron powder characterized in that a metal or metalloid boride is present as an inhibitor.   White cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles, and crystal grain growth between and / or inside the nanocrystal particles (1) Metal or metalloid carbide, (2) Metal or metalloid oxide, (3) Metal or metalloid nitride, (4) Metal or metalloid carbonitride, (5 (2) Two or more kinds selected from (1) to (6) of metal or metalloid silicide (silicide) or (6) metal or metalloid boride (boride) are present. High hardness nanocrystalline white cast iron powder.   White cast iron powder containing 2.2 to 3.5% by mass of carbon made of white cast iron nanocrystal particles or aggregates thereof contains 0.005 to 1.0% by mass of oxygen in the form of a metal oxide. 14. The high-hardness nanocrystalline white cast iron powder according to any one of claims 1 to 13.   In order to prevent denitrification of the aggregate of white cast iron nanocrystal particles during the solidification molding process, a metal element having a higher chemical affinity with nitrogen than iron in the nanocrystal white cast iron is contained. Item 15. The high-hardness nanocrystalline white cast iron powder according to any one of Items 1-14.   White cast iron nanocrystal particles are obtained by mechanically milling (MM) or mechanical alloying (MA) using a ball mill or the like for the material of the white cast iron forming component in the form of lump, flake, granule or powder. The high-hardness nanocrystalline white cast iron powder according to any one of claims 1 to 15.   White cast iron nanocrystal particles are one of lump, flake, granule or powder ordinary carbon steel, alloy steel, white cast iron, gray cast iron, mottle cast iron, spheroidal graphite cast iron, alloy cast iron, other alloy elements or alloys Claims obtained by mechanically milling (MM) or mechanical alloying (MA) a constituent material of white cast iron selected from one or more materials using a ball mill or the like. Item 16. The high-hardness nanocrystalline white cast iron powder according to any one of Items 1 to 15.   In the mechanical alloying (MA) or mechanical milling (MM) process, by adjusting the mechanical energy input by selecting the mass ratio of the grinding media used for the ball mill and the raw material powder and / or the operation energy of the ball mill, etc. (1) Ferrite particles and particle diameters of carbides, nitrides or carbonitrides as dispersion / precipitates in aggregates of nanocrystal particles, (2) Generation of these dispersions / precipitates, or (3) Generation thereof 18. The high-hardness nanocrystalline white cast iron powder according to claim 1, wherein at least one selected from (1) to (3) is controlled.   Nanocrystal particle aggregate (powder) obtained by mechanically alloying (MA) or mechanical milling (MM) of white cast iron powder containing 2.2 to 3.5% by mass of carbon composed of aggregates of white cast iron nanocrystal particles As an atomic bond promoting substance in the solidification molding process between the body) or a delayed fracture suppressing / preventing substance of the solidified compact (bulk material), 0.01 to 5.0% by mass of titanium or zirconium is contained. The high-hardness nanocrystalline white cast iron powder according to any one of claims 1 to 18.   A high-hardness, high-strength, tough nanocrystalline white cast iron bulk material, comprising a large number of nanocrystalline white cast iron powders according to any one of claims 1 to 19 consolidated.   By mechanically milling (MM) or mechanical alloying (MA) a white cast iron forming component material containing 2.2 to 3.5% by mass of carbon using a ball mill or the like. A method for producing a high-hardness nanocrystalline white cast iron powder comprising obtaining a high-hardness nanocrystalline white cast iron powder comprising an aggregate of white cast iron nanocrystalline particles.   A lump, flake, granular or powdery white cast iron forming component material containing 2.2 to 3.5% by mass of carbon is lump, flake, granular or powdery ordinary carbon steel, alloy steel, white cast iron, The high hardness according to claim 21, wherein the cast iron is selected from gray cast iron, mottled cast iron, spheroidal graphite cast iron, alloy cast iron, other alloy elements or alloys, or two or more substances. Method for producing nanocrystalline white cast iron powder.   In the mechanical alloying (MA) or mechanical milling (MM) process, by adjusting the mechanical energy input by selecting the mass ratio of the grinding media used for the ball mill and the raw material powder and / or the operation energy of the ball mill, etc. (1) Ferrite particles and particle diameters of carbides, nitrides or carbonitrides as dispersion / precipitates in aggregates of nanocrystal particles, (2) Generation of these dispersions / precipitates, or (3) Generation thereof The method for producing high-hardness nanocrystalline white cast iron powder according to any one of claims 21 and 22, wherein one or more selected from (1) to (3) are controlled. High melting point such as chromium, vanadium, titanium, zirconium, molybdenum, niobium, tantalum, tungsten, and the like in white, cast iron forming component material containing 2.2 to 3.5% by mass of carbon By adding 0.5 to 10% by mass or more of the element and mechanical milling (MM) or mechanical alloying (MA), the white cast iron nanocrystal particles or aggregates thereof are in a single state and / or others. The method for producing high-hardness nanocrystalline white cast iron powder according to any one of claims 21 to 23, wherein the carbide, nitride, or carbonitride is present in a coexisting state.   A state in which a carbide, nitride or carbonitride containing a high melting point element as a basic composition is dispersed and precipitated in the ferrite phase of the parent phase alone and / or coexisting with other carbides, nitrides or carbonitrides. In order to obtain the above, in addition to the adjustment of the concentration of each refractory element, the mechanical energy in the mechanical alloying (MA) or mechanical milling (MM) process and / or the temperature and time of MA and MM are effectively controlled. The method for producing ultra-high hardness nanocrystalline white cast iron powder according to any one of claims 21 to 24.   In the hot solidification molding of nanocrystalline white cast iron powder by the method according to any one of claims 21 to 25, (1) solidification molding temperature, (2) solidification molding time, (3) solidification molding pressure, or ( 4) Dispersing carbide, nitride or carbonitride effectively by controlling any one or more selected from (1) to (4) of heat treatment such as annealing after solidification molding -A method for producing a tough nanocrystalline white cast iron bulk material with high hardness, high strength and toughness characterized by precipitation.   The white cast iron nanocrystal particle powder according to any one of claims 16 to 19, wherein the plasma sintering is performed at a temperature of 500 ° C to 900 ° C, hot pressing, sheath rolling (Sheath Rolling). By performing solidification molding treatment such as hot forging, extrusion molding, hot isostatic pressing (HIP), vacuum hot solidification molding or explosion molding, nano carbide, nano nitride or nano carbonitride A method for producing a high hardness, high strength and tough nanocrystalline white cast iron bulk material, characterized in that any one or more dispersion / precipitation strengthened nanocrystalline white cast iron bulk material is obtained.   The powder of white cast iron nanocrystal particles according to any one of claims 16 to 19 is subjected to discharge plasma sintering, hot pressing, sheath rolling, extrusion molding, hot forging, hot in a temperature range showing superplasticity. Dispersion and strengthening with one or more compounds of nano carbide, nano nitride or nano carbonitride by performing vacuum hot solidification molding (superplastic solidification molding) such as isotropic pressure molding (HIP) A high hardness, high strength and tough nanocrystalline white cast iron bulk material, characterized by making it into a type nanocrystalline white cast iron bulk material.   The powder of white cast iron nanocrystal particles according to any one of claims 16 to 19, wherein discharge powder sintering at a temperature of 500 ° C to 900 ° C, hot pressing, extrusion molding, hot forging, hot isotropy Solidification processing is performed by pressure-press molding (HIP), vacuum hot solidification molding such as rolling, or explosion molding to form a nanocrystalline white cast iron bulk material, and then the white cast iron bulk material is molded in a temperature range showing superplasticity. A method for producing a bulk material of nanocrystalline white cast iron that is tough and has high hardness, high strength and toughness. The atmosphere in which mechanical milling or mechanical alloying is performed is any one selected from (1) an inert gas such as argon gas, (2) N ₂ gas, or (3) NH ₃ gas, or (4) (1 The high hardness, high strength and tough nanocrystalline white cast iron bulk material according to any one of claims 21 to 29, wherein the atmosphere is a mixed gas of two or more selected from (1) to (3). Manufacturing method. 30. The atmosphere according to any one of claims 21 to 29, wherein the atmosphere for performing mechanical milling or mechanical alloying is a gas atmosphere to which a reducing substance such as a slight amount of H ₂ gas is added. A manufacturing method of high strength and tough nanocrystalline white cast iron bulk material. Atmosphere performing mechanical milling or mechanical alloying is, any one of claims 21-29, characterized in that a vacuum or a reducing atmosphere was added a reducing substance, such as some of the H ₂ gas in a vacuum or vacuum A method for producing a nanocrystalline white cast iron bulk material having high hardness, high strength and toughness as described in 1. The composition of nanocrystalline white cast iron contains 0 to 40% by mass of other elements, and the temperature of solidification molding is within 20% above and below the eutectoid temperature of cast iron (about 730 ° C.). The method for producing a bulk material of high hardness, high strength and tough nanocrystalline white cast iron according to any one of claims 21 to 32, wherein the temperature is within a range.