Method for producing high-rigidity iron-based alloy

Abstract

To provide a method for producing a high-rigidity iron-based alloy that suppresses aggregation of titanium boride in an iron-based matrix.SOLUTION: The present invention relates to a method for producing a high-rigidity iron-based alloy, the method including (i) a step of mixing an iron-based powder and a titanium boride powder to obtain a mixed powder, and (ii) a step of processing the mixed powder obtained in step (i) by an additive manufacturing method involving laser irradiation to obtain a high-rigidity iron-based alloy, the method including a step in which a laser scanning speed is 1000 mm / second to 2600 mm / second.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a highly rigid iron-based alloy containing a matrix made of iron or an iron alloy and fine titanium boride dispersed in the matrix by additive manufacturing. [Background technology]

[0002] Currently, steels and iron alloys are the most widely used structural metal materials. These metals exhibit a wide variety of structural changes through the addition of alloying elements and heat treatment, allowing for a wide range of control over their mechanical properties, such as strength, toughness, and ductility.

[0003] However, because rigidity, which is important in the design of actual parts, is a value specific to a material that is directly related to the bonding forces between atoms, it has been thought that it would be difficult to significantly improve rigidity.

[0004] Under these circumstances, research and development has been conducted into dispersing compound particles such as borides with a high Young's modulus in iron or iron alloys with the aim of increasing rigidity. For example, Patent Document 1 describes a titanium boride-dispersed steel characterized in that it contains titanium boride particles having an average particle size of 3.0 μm or less in terms of projected area circle equivalent diameter, the titanium boride particles exist in the form of aggregates, the average size of the aggregates is 5 μm or more and 20 μm or less, and the aggregates are scattered throughout the steel.

[0005] Furthermore, Patent Document 2 describes a method for producing a high-stiffness iron-based alloy, which includes: (i) a step of mixing a powder of an iron-titanium intermetallic compound, a powder of an iron boride intermetallic compound, and a carbon-containing powder to obtain a mixed powder; and (ii) a step of treating the mixed powder obtained in step (i) by an additive manufacturing method involving sintering or laser irradiation to obtain a high-stiffness iron-based alloy. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-131661 [Patent Document 2] Japanese Patent Application Publication No. 2023-90021 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the prior art, the conditions of the additive manufacturing method have not been examined, and the factors that may cause the aggregation of titanium boride have not been identified.

[0008] Therefore, an object of the present invention is to provide a method for producing a high-rigidity iron-based alloy in which the aggregation of titanium boride in the iron-based matrix is ​​suppressed. [Means for solving the problem]

[0009] The present inventors have investigated various means for solving the above problems and have found that in a method for manufacturing a high-rigidity iron-based alloy containing a matrix made of iron or an iron alloy and fine titanium borides dispersed in the matrix by an additive manufacturing method, by controlling the laser scanning speed within a certain speed range, it is possible to suppress aggregation of the fine titanium borides dispersed in the matrix made of iron or an iron alloy, and have completed the present invention.

[0010] That is, the gist of the present invention is as follows. (1) A method for producing a high-rigidity iron-based alloy, comprising: (i) a step of mixing an iron-based powder with a titanium boride powder to obtain a mixed powder; and (ii) a step of processing the mixed powder obtained in step (i) by an additive manufacturing method involving laser irradiation to obtain a high-rigidity iron-based alloy, wherein the laser scanning speed is 1000 mm / sec to 2600 mm / sec. (2) The method according to (1), wherein in step (i), the volume ratio of the titanium boride powder is 5% to 40% by volume relative to the total volume of the high-modulus iron-based alloy. (3) The method according to (1) or (2), wherein in step (ii), the laser output is 50 W to 300 W. (4) The method according to any one of (1) to (3), wherein in step (ii), the distance between the laser spots is 0.02 mm to 0.20 mm. (5) The method according to any one of (1) to (4), wherein in step (ii), the thickness of the high-rigidity iron-based alloy formed per scan is 0.01 mm to 0.10 mm. In step (6)(ii), the laser energy density irradiated to the mixed powder is 20 J / mm 3 ~120J / mm 3 The method according to any one of (1) to (5), (7) The method according to any one of (1) to (6), wherein in step (ii), the additive manufacturing method is carried out by the PBF method. [Effects of the Invention]

[0011] The present invention provides a method for producing a high-rigidity iron-based alloy in which the aggregation of titanium boride in the iron-based matrix is ​​suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out an additive manufacturing method using a PBF method. [Figure 2] FIG. 10 is a diagram showing EPMA elemental mapping of Example 2. [Figure 3] FIG. 10 shows EPMA elemental mapping of Example 10. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will now be described in detail. In this specification, the features of the present invention will be described with reference to the drawings as appropriate. In the drawings, the dimensions and shapes of each part are exaggerated for clarity, and the actual dimensions and shapes are not accurately depicted. Therefore, the technical scope of the present invention is not limited to the dimensions and shapes of each part shown in these drawings. Note that the method for producing a high-modulus iron-based alloy of the present invention is not limited to the following embodiments, and can be embodied in various forms including modifications and improvements that can be made by those skilled in the art, without departing from the gist of the present invention.

[0014] Each of steps (i) and (ii) of the present invention will be explained below.

[0015] In the step (i) of the present invention, an iron-based powder and a titanium boride powder are mixed to obtain a mixed powder.

[0016] The iron-based powder is a powder consisting of iron-based elements that form the matrix of the high-rigidity iron-based alloy produced by the production method of the present invention, and is not limited to any powder containing iron, and a wide range of iron alloys can be used, including ferritic, austenitic (e.g., SUS316L), martensitic, etc. Examples of iron-based powders include pure iron powder as iron powder, and alloy powders such as pre-alloyed iron powder, partially diffused alloyed steel powder, mixed powders (segregation-preventing mixed powders), pre-alloyed steel powders (low-alloy steel powders), and stainless / special steel powders (high-alloy steel powders).

[0017] The average particle size of the iron-based powder is not limited, but is, for example, usually 25 μm to 200 μm, and in one embodiment 45 μm to 140 μm, as D50 in the volume-based particle size distribution measured by a laser diffraction / scattering method.

[0018] When the average particle size of the iron-based powder is within the above range, the iron-based powder and the titanium boride powder can be mixed easily and uniformly.

[0019] Titanium boride powder is a powder containing diboride represented by the chemical formula TiB2.

[0020] The average particle size of the titanium boride powder is not limited, but is typically 0.1 μm to 5 μm, in one embodiment 1 μm to 4 μm, and in one embodiment 1 μm to 3 μm, as D50 in the volume-based particle size distribution measured by a laser diffraction / scattering method. Alternatively, the average particle size of the titanium boride powder is not limited, but is typically 0.1 μm to 5 μm, in one embodiment 1 μm to 4 μm, and in one embodiment 1 μm to 3 μm, as measured by an air permeability method.

[0021] When the average particle size of the titanium boride powder is within the above range, the iron-based powder and the titanium boride powder can be mixed easily and uniformly.

[0022] The iron-based powder and titanium boride powder may contain one or more other elements, such as carbon, nickel, cobalt, chromium, magnesium, molybdenum, manganese, etc., depending on the components required in the final high-rigidity iron-based alloy.

[0023] The mixing ratio of the iron-based powder and the titanium boride powder can be changed depending on the composition of each material and the amount of titanium boride contained in the high-rigidity iron-based alloy to be produced. For example, the iron-based powder and the titanium boride powder are mixed so that the volume ratio of the titanium boride powder is typically 5% to 40% by volume, in one embodiment 10% to 30% by volume, in another embodiment 15% to 25% by volume, for example 20% by volume, based on the total volume of the high-rigidity iron-based alloy to be finally obtained. Here, "volume" refers to the volume determined by the true density and mass.

[0024] By ensuring that the mixing ratio of the iron-based powder and the titanium boride powder is within the above range, it is possible to ensure that the amount of titanium boride necessary to provide sufficient hardness in the matrix made of iron or iron alloy in the finally obtained high-rigidity iron-based alloy.

[0025] In step (i), additives such as powders containing one or more other elements, for example, carbon, nickel, cobalt, chromium, magnesium, molybdenum, manganese, etc., and lubricants may be mixed in addition to the iron-based powder and titanium boride, depending on the components required in the final high-rigidity iron-based alloy.

[0026] The order and method of mixing the powders, i.e., the iron-based powder, the titanium boride powder, and optionally the powder containing one or more other elements or additives, are not limited, and mixing can be performed using any mixing means known in the art. For example, the iron-based powder and the titanium boride powder may be mixed together, followed by the addition of any powder containing one or more other elements or additives, or all of the powders may be mixed simultaneously. The powders can be mixed, for example, at room temperature (e.g., 10°C to 30°C), by placing the powders in a container, closing the lid to prevent leakage, and then shaking the container, e.g., by shaking up and down and / or by inversion, for 10 to 30 minutes. Examples of mixing devices that can be used include a V-type mixer (V-type powder mixer), a ball mill, and a vibration mill. The powders may also be mixed by wet mixing. The mixing of the iron-based powder and the titanium boride powder in the present invention does not necessarily require micro-uniformity (e.g., uniformity on the nanometer scale), but rather requires macro-uniformity (e.g., uniformity on the micrometer scale). This is because, as explained below, by controlling the laser scanning speed within a specific range, convective stirring occurs in the molten pool due to rapid heating and cooling, thereby ensuring a high stirring effect in the molten pool. This high stirring effect can create a state in which titanium boride is dispersed in the iron-based matrix while suppressing the aggregation of fine titanium boride in the iron-based matrix, i.e., the formation of titanium boride aggregates.

[0027] By the step (i) of the present invention, it is possible to obtain a mixed powder in which an iron-based powder, a titanium boride powder, and optionally a powder containing one or more other elements or an additive are dispersed.

[0028] In step (ii), the mixed powder obtained in step (i) is processed by an additive manufacturing method involving laser irradiation to obtain a high-rigidity iron-based alloy.

[0029] In step (ii) of the present invention, the additive manufacturing method involving laser irradiation is a method in which a laser is irradiated onto a mixed powder as a raw material to melt and solidify only specific portions, and this process is repeated to form an alloy without a mold. Note that the laser irradiation may be performed based on slice data converted from 3D data.

[0030] The additive manufacturing method involving laser irradiation enables rapid heating, convective stirring, and rapid cooling of mixed powder.

[0031] In the additive manufacturing method involving laser irradiation, the laser scanning speed is 1000 mm / sec to 2600 mm / sec.

[0032] "Laser scanning speed" means the distance per second that the laser scans on the target, i.e., the mixed powder.

[0033] By controlling the laser scanning speed within the above range, convective stirring occurs in the molten pool due to rapid heating and cooling, thereby ensuring a high stirring effect in the molten pool. As a result, aggregation of fine titanium boride particles in the iron-based matrix, i.e., the formation of titanium boride aggregates, is suppressed, and the titanium boride can be dispersed in the iron-based matrix.

[0034] The laser wavelength is not limited as long as it is a laser wavelength that is normally used in an additive manufacturing method involving laser irradiation. The "laser wavelength" refers to the wavelength of the irradiated laser. For example, the laser wavelength is normally 900 nm to 1200 nm, and in one embodiment, 1020 nm to 1120 nm.

[0035] The laser output is not limited as long as it is a laser output normally used in an additive manufacturing method involving laser irradiation. The "laser output" refers to the energy of the irradiated laser per unit time. For example, the laser output is normally 50 W to 300 W, and in one embodiment, 77 W to 255 W.

[0036] The distance between laser spots is not limited as long as it is a distance between laser spots that is typically used in additive manufacturing methods involving laser irradiation. The "distance between laser spots" refers to the circle-equivalent diameter of the area of ​​the laser irradiated onto the mixed powder in a stationary state where the laser is not scanning. For example, the distance between laser spots is typically 0.02 mm to 0.20 mm, and in one embodiment, 0.03 mm to 0.10 mm.

[0037] The thickness of the high-rigidity iron-based alloy formed by the irradiated laser per scan is not limited as long as it is a thickness that is normally used in additive manufacturing methods involving laser irradiation. For example, the thickness of the high-rigidity iron-based alloy formed per scan is normally 0.01 mm to 0.10 mm, and in one embodiment, 0.02 mm to 0.05 mm.

[0038] The laser energy density irradiated to the mixed powder is calculated based on the above-described laser scanning speed, laser output, laser spot distance, and thickness of the high-rigidity iron-based alloy formed per scanning, using the following formula: Laser energy density (J / mm 3 ) = laser power (W) / (laser scanning speed (mm / sec) × thickness of high-rigidity iron-based alloy formed per scan (mm) × distance between laser spots (mm)) "Laser energy density" means the amount of energy that a laser gives per unit volume of mixed powder. The laser energy density is usually 15 J / mm 3 ~200J / mm 3 , 20 J / mm in one embodiment 3 ~120J / mm 3 , 30 J / mm in one embodiment 3 ~120J / mm 3, 30 J / mm in one embodiment 3 ~105J / mm 3 is.

[0039] Therefore, by controlling the laser scanning speed, as well as the laser output, the distance between the laser spots, and the thickness of the high-rigidity iron-based alloy formed per scan within the above-mentioned ranges, it is possible to suppress the supply of excessive energy to the mixed powder, prevent the growth of titanium boride particles, and form a state in which fine titanium boride is dispersed in the iron-based matrix without aggregation.

[0040] An example of an additive manufacturing method involving laser irradiation is powder bed fusion (PBF).

[0041] The PBF method involves spreading mixed powder and irradiating the area to be shaped with a laser, melting and solidifying it, and layering it to form the alloy.

[0042] In the PBF method, the alloy precursor is irradiated with a laser to melt it, and then cooled rapidly, usually at a rate of 10,000 K / sec or more, to produce the alloy.

[0043] Figure 1 shows a schematic diagram of an example of an apparatus for implementing additive manufacturing using the PBF method. In Figure 1, first, mixed powder 1 loaded into a raw material container is pushed up inside an argon-substituted cover 7, and the pushed-up mixed powder 1 is spread out by a blade 2. Next, a laser 4 is irradiated by a laser generator 3 onto the mixed powder 1 spread out by the blade 2. When the laser 4 is irradiated onto the mixed powder 1, the powder particles in the mixed powder 1 melt and bond together, forming an iron-based alloy 5 on a base plate 6. These steps are repeated (additive manufacturing) while the base plate 6 is lowered, and the iron-based alloy 5 is molded.

[0044] In a method for producing an iron-based alloy having titanium boride in an iron or iron alloy matrix using an iron-based powder and titanium boride powder as raw materials, when continuous casting of the molten metal is used, titanium boride grows during the casting process. The longer the particles are in an environment where they can grow, particularly a static environment (a stationary environment), the faster they grow. Therefore, to maintain the fineness of the titanium boride in the iron-based matrix, it is preferable to shorten the time that the titanium boride can grow and / or aggregate in an agitated environment. In the present invention, to produce an iron-based alloy having fine titanium boride in an iron or iron alloy matrix using an iron-based powder and titanium boride powder, an additive manufacturing method involving laser irradiation with controlled laser scanning speed is used. This method controls the amount of energy imparted to the powder, ensures high agitation of the molten pool created by high-speed laser irradiation and scanning, and also increases the cooling rate after the powder melts. As a result, the growth and aggregation time of titanium boride particles (crystals) can be shortened, resulting in a finer dispersion of titanium boride.

[0045] The high-modulus iron-based alloy obtained by the manufacturing method of the present invention is a high-modulus iron-based alloy that contains a matrix made of iron or an iron alloy and fine titanium boride particles dispersed in the matrix.

[0046] The iron alloy that constitutes the matrix of the high-modulus iron-based alloy obtained by the manufacturing method of the present invention can be a wide range of alloys, including ferritic, austenitic, and martensitic alloys.

[0047] In the high-rigidity iron-based alloy obtained by the manufacturing method of the present invention, the circle-equivalent average grain size of the crystal grains in the IPF image of the matrix made of iron or iron alloy is not limited, but is usually more than 1 μm, preferably more than 1 μm to 5 μm.

[0048] The method for measuring the average circle-equivalent diameter of crystal grains using IPF images of a matrix made of iron or an iron alloy can be performed by first taking three EBSD (Electron Backscattered Diffraction Pattern)-IPF (Inverse Pole Figure) images of the high-rigidity iron-based alloy to be measured, then randomly selecting 30 crystal grains in each image, calculating the area of ​​each selected crystal grain, calculating the circle-equivalent diameter from the calculated area, and finally taking the arithmetic mean of the calculated circle-equivalent diameters.

[0049] When the average grain size of the crystal grains of the matrix made of iron or iron alloy is within the above range, the iron-based alloy has high strength and high rigidity.

[0050] The titanium boride contained in the high-stiffness iron-based alloy obtained by the manufacturing method of the present invention has a regular crystalline structure and is a compound in which the constituent atoms are tightly bonded. Therefore, its Young's modulus, which directly reflects the bonding strength, is extremely high. Furthermore, because titanium boride is thermodynamically stable in iron alloys, it does not undergo crystallographic changes resulting from reactions between titanium boride and the iron or iron alloy matrix, such as the intrusion or substitution of heteroatoms or the formation of other complex compounds. As a result, titanium boride maintains its strong bonding strength even in iron alloys, maintains its high Young's modulus, and can fully demonstrate its excellent properties as a reinforcing particle that contributes to the high stiffness of iron-based alloys. Therefore, the iron-based alloy of the present invention can have an extremely high Young's modulus.

[0051] The average particle size of titanium boride, as the diameter equivalent to a circle having a projected area in an SEM image, is usually 0.2 μm to 0.9 μm, 0.2 μm to 0.6 μm in one embodiment, and 0.2 μm to 0.4 μm in another embodiment.

[0052] The method for measuring the average circle-equivalent particle size using SEM images of titanium boride can be carried out by first taking three BSE-SEM images (backscattered electron images) of the high-rigidity iron-based alloy to be measured, then randomly selecting 300 titanium borides from each image, calculating the area of ​​each selected titanium boride, calculating the circle-equivalent diameter from the calculated area, and finally taking the arithmetic mean value of the calculated circle-equivalent diameters.

[0053] By having the average particle size of the titanium boride within the above range, when machining a high-rigidity iron-based alloy, the stress applied to the cutting tool when cutting the high-hardness titanium boride is dispersed, reducing breakage of the cutting tool and improving machinability while maintaining high rigidity.

[0054] The particle size of the titanium boride is preferably uniform. Although the particle size of the titanium boride is not limited, for example, when the titanium boride particles follow a normal distribution, 68% of the titanium boride particles generally fall within the range of the average particle size ±0.20 μm, preferably ±0.17 μm.

[0055] The degree of dispersion (dispersibility) of titanium boride is not limited, but for example, in a 200 μm×200 μm area, the dispersibility is such that the number of particles in each 100 μm×100 μm partial area is approximately the same.

[0056] By ensuring that the particle size and dispersibility of the titanium boride are as described above, when machining a high-rigidity iron-based alloy, the stress applied to the cutting tool when cutting the high-hardness titanium boride is dispersed, reducing breakage of the cutting tool and improving machinability while maintaining high rigidity.

[0057] The content of titanium boride is generally 5 to 40% by volume, 10 to 30% by volume in one embodiment, and 15 to 25% by volume in another embodiment, relative to the total volume of the high-modulus iron-based alloy.

[0058] When the content of titanium boride is within the above range, the titanium boride does not aggregate or coalesce with other borides, and the high-rigidity iron-based alloy can exhibit sufficient mechanical properties, particularly high rigidity.

[0059] Therefore, the high-rigidity iron-based alloy obtained by the manufacturing method of the present invention exhibits sufficient mechanical properties, particularly high rigidity and high Young's modulus, due to the presence of titanium boride, and furthermore, because the titanium boride is fine, it can be easily cut in the cutting process without destroying the cutting tool.

[0060] The high-modulus iron-based alloy obtained by the manufacturing method of the present invention may contain, in addition to titanium boride, one or more other elements, such as carbon, nickel, cobalt, chromium, magnesium, molybdenum, manganese, and compounds thereof, such as borides and carbides, depending on the components required in the final high-modulus iron-based alloy. [Example]

[0061] Hereinafter, several examples of the present invention will be described, but it is not intended that the present invention be limited to those shown in these examples.

[0062] Examples 1 to 19 The iron-based alloys of Examples 1 to 19 were produced by the following steps (i) and (ii).

[0063] (i) A step of mixing an iron-based powder with a titanium boride powder to obtain a mixed powder. In step (i), iron-based powder (SUS316L) was used as the iron-based powder, and titanium boride (TiB2) powder (particle size measured by air permeability method: 1.95 μm, B: 30.6 mass%, TC: 0.06 mass%, O: 1.1 mass%, N: 0.41 mass%, Fe: 0.15 mass%, particle size measured by laser diffraction / scattering method: D10: 1.159 μm, D50: 2.437 μm, D90: 3.943 μm) was used as the titanium boride powder. These powders were adjusted so that the volume ratio of titanium boride was 20 volume % relative to the total volume of the iron-based alloy. Specifically, 2000 g of SUS316L (true density 7.98 g / cm3) was used. 3 ), TiB2: 283g (true density 4.52g / cm 3 ) were mixed (SUS316L:TiB2=2000 / 7.98:283 / 4.52=8:2) and placed in a stainless steel can, and stirred for about 20 minutes by inverting at a rotation speed of one rotation per second to obtain a mixed powder.

[0064] (ii) A step of processing the mixed powder obtained in step (i) by an additive manufacturing method involving laser irradiation to obtain an iron-based alloy. In step (ii), the mixed powder obtained in step (i) was processed by the additive manufacturing method with laser irradiation (L-PBF) shown in Figure 1 under the conditions shown in Table 1 to produce an iron-based alloy. Other conditions were as follows: Laser spot distance: 0.05 mm Thickness of high-rigidity iron-based alloy formed per scan: 0.03 mm

[0065] Table 1 shows the macrohardness of the iron-based alloys of Examples 1 to 19. FIG. 2 shows a diagram illustrating EPMA elemental mapping of Example 2. FIG. 3 shows EPMA elemental mapping of Example 10. In FIGS. 2 and 3, for B and Ti, the white areas in the diagrams represent titanium boride. Note that titanium boride is not completely absent in the black areas, but is present in a finely dispersed form. In FIGS. 2 and 3, for Fe, the white areas in the diagrams represent the iron-based matrix, and the black areas represent titanium boride.

[0066] [Table 1]

[0067] Table 1 and Figure 2 show that under the molding conditions of Example 2, the laser energy density was low, leaving a large amount of titanium boride powder in the iron-based matrix, and the stirring action due to the high laser scanning speed dispersed the titanium boride powder into the iron-based matrix. Table 1 and Figure 3 show that under the molding conditions of Example 10, the laser energy density was high, leaving a small amount of titanium boride powder in the iron-based matrix, and the titanium boride powder dissolved into the iron-based matrix, but the titanium boride powder dispersed into the iron-based matrix even at a laser scanning speed that was not that fast. Therefore, by controlling the laser scanning speed, the applied laser energy density is reduced, thereby controlling the refinement of titanium boride and allowing a small amount of titanium boride to be dissolved into the iron-based matrix. Furthermore, by adjusting the stirring action of the molten pool, the titanium boride is uniformly dispersed without agglomerating. As a result, it was found that it is possible to produce a high-rigidity iron-based alloy having a structure in which titanium boride that is slightly smaller than the particle size of the powder and titanium boride that has been finely dispersed after melting the matrix are uniformly dispersed without agglomerating with each other.

[0068] If the laser scanning speed is less than 1000 mm / s, the stirring effect is small and ineffective. On the other hand, if the laser scanning speed exceeds 2600 mm / s, the output must be increased to optimize the energy density, which causes spatter and degrades the quality of the molded object.

[0069] Furthermore, by utilizing the L-PBF method, rapid heating and cooling are possible compared to powder melting using the DED method, and it was found that the growth and coarsening of titanium boride can be minimized.

[0070] This patent application is based on the results of the "Aichi Knowledge Hub Priority Research Project Phase IV" (Project Core Industry). [Explanation of symbols]

[0071] 1. Mixed powder, 2. Blade, 3. Laser generator, 4. Laser, 5. Iron-based alloy, 6. Base plate, 7. Cover

Claims

1. (i) mixing an iron-based powder and a titanium boride powder to obtain a mixed powder; and (ii) A step of treating the mixed powder obtained in step (i) by an additive manufacturing method involving laser irradiation to obtain a high-rigidity iron-based alloy, A process in which the laser scanning speed is 1000 mm / sec to 2600 mm / sec 1. A method for producing a high stiffness iron-based alloy, comprising:

2. 2. The method according to claim 1, wherein in step (i), the volume fraction of the titanium boride powder is 5% to 40% by volume relative to the total volume of the high-modulus iron-based alloy.

3. 3. The method according to claim 2, wherein in step (ii), the laser output is 50 W to 300 W, the laser spot distance is 0.02 mm to 0.20 mm, and the thickness of the high-rigidity iron-based alloy formed per scan is 0.01 mm to 0.10 mm.

4. In the step (ii), the laser energy density irradiated to the mixed powder is 20 J / mm ３ ~120 J / mm ３ The method of claim 3, wherein

5. The method according to any one of claims 1 to 4, wherein in step (ii), the additive manufacturing method is carried out by a PBF method.

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