Austenitic non-magnetic steel, powder metal material for additive manufacturing, and method for manufacturing austenitic non-magnetic steel

Abstract

To provide an austenitic nonmagnetic steel that has high strength and is excellent in elongation, a lamination shaping powder metal material, and a method for producing austenitic nonmagnetic steel.SOLUTION: Provided are an austenitic nonmagnetic steel, and the nonmagnetic steel contains Mn: 8.0 to 15.0%, N: 0.05 to 0.50%, C: 0.20 to 1.00%, Cr: 2.0 to 15.0%, V: 3.0% or less in mass%, a lamination shaping powder metal material, and a method for producing austenitic nonmagnetic steel.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an austenitic non-magnetic steel, a powder metal material for additive manufacturing, and a method for manufacturing an austenitic non-magnetic steel. [Background technology]

[0002] Some nickel, cobalt, and titanium alloys are known to be non-magnetic and have a strength of 1500 MPa or more. However, these alloys contain large amounts of rare elements, making them expensive and posing a high resource risk. Conventionally, additive manufacturing techniques that take durability into consideration have been developed. Patent Document 1 discloses a method for manufacturing an iron alloy by metal additive manufacturing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-195588 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional techniques do not take into consideration high strength, strength against large external forces (1500 MPa or more), and elongation, and are therefore not suitable for use as a material in parts that are particularly subject to large external forces (such as the rotor body of a high-speed rotating electrical machine). Furthermore, austenitic non-magnetic steels with the above-mentioned strength and elongation are non-magnetic and can be used to provide a variety of shaped products, but it has been difficult to obtain such austenitic non-magnetic steels.

[0005] The present invention provides austenitic non-magnetic steel with high strength and excellent elongation, a powder metal material for additive manufacturing, and a method for manufacturing austenitic non-magnetic steel. [Means for solving the problem]

[0006] (1) The present invention is Austenitic non-magnetic steel, The non-magnetic steel comprises, in mass%, Mn: 8.0 to 15.0%, N: 0.05 to 0.50%, C: 0.20~1.00%, Cr: 2.0 to 15.0%, V:3.0% or less 、 Mo: 3.0% or less The balance is Fe and unavoidable impurities consists of , an austenitic non-magnetic steel. (2) The present invention is A powder metal material for additive manufacturing, comprising: The powder metal material comprises, in mass %, Mn: 8.0 to 15.0%, N:0.05~0.5%、 C: 0.20~1.00%, Cr: 2.0 to 15.0%, V: 3.0% or less, Mo: 3% or less The balance is Fe and unavoidable impurities consists of It is a powder metal material made of austenitic non-magnetic steel. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide austenitic non-magnetic steel that has high strength and excellent elongation, a powder metal material for additive manufacturing, and a method for manufacturing austenitic non-magnetic steel. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail.

[0009] <Austenitic non-magnetic steel> The austenitic non-magnetic steel of the present invention is In mass%, Mn: 8.0 to 15.0%, N: 0.05 to 0.50%, C: 0.20~1.00%, Cr: 2.0 to 15.0%, V:3.0% or less It is an austenitic non-magnetic steel containing Unless otherwise specified, the content of each alloying element is a mass value with the entire austenitic non-magnetic steel being 100%.

[0010] The austenitic non-magnetic steel of the present invention contains 8.0 to 15.0% of Mn. Mn is an essential additive element for forming the above steel into an austenitic structure and making it nonmagnetic. Considering the synergistic effect with N and C, which are also added at the same time, an austenitic structure can be obtained if the Mn content is 8.0% or more. On the other hand, considering the stability of the austenitic structure, the saturation of strength, and the risk of ignition due to static electricity, the Mn content is preferably 15.0% or less. The Mn content is preferably 10.0 to 15.0%, and more preferably 10.0 to 12.0%.

[0011] Austenitic steel materials containing large amounts of Mn are called high manganese steels and are known as difficult-to-process materials. Conventionally, they have mainly been produced by casting, but additive manufacturing, for example, net-shape manufacturing, is preferable as it improves processability.

[0012] The austenitic non-magnetic steel of the present invention contains N in an amount of 0.05 to 0.50%. N stabilizes the austenite structure, dissolves in it, and forms nitrides with Cr and V, increasing strength. It is also effective in improving corrosion resistance. To achieve these effects, the N content must be 0.05% or more. However, if the N content exceeds 0.50%, it can gasify during additive manufacturing in the production of austenitic non-magnetic steel, making voids more likely to occur, so the N content must be 0.50% or less. The N content is preferably 0.10 to 0.50%, and more preferably 0.15 to 0.25%.

[0013] N may be contained in the product, that is, in the austenitic non-magnetic steel stage. For example, N may be contained in the raw material powder, or may be added by controlling the atmosphere during raw material powder processing. Furthermore, N may be added by adding it through a nitrogen addition process during additive manufacturing. As mentioned above, it is sufficient for N to be contained in the austenitic non-magnetic steel.

[0014] The austenitic non-magnetic steel of the present invention contains C in an amount of 0.20 to 1.00%. C has the effect of strengthening the austenite structure through solid solution strengthening and by forming carbides with Cr and V to increase strength. To obtain these effects, the C content must be 0.20% or more. On the other hand, if the C content exceeds 1.00%, elongation becomes small, so it must be 1.00% or less. The C content is preferably 0.30 to 0.90%, and more preferably 0.30 to 0.40%.

[0015] The austenitic non-magnetic steel of the present invention contains 2.0 to 15.0% of Cr. Cr is effective in increasing the amount of nitrogen added, improving strength by forming carbonitrides, and improving corrosion resistance. To obtain these effects, the Cr content must be 2.0% or more. However, if the Cr content exceeds 15.0%, the strength saturates, so the Cr content must be 15.0% or less. The Cr content is preferably 3.0 to 13.0%, more preferably 4.0 to 12.0%, and further preferably 5.0 to 11.0%.

[0016] The austenitic non-magnetic steel of the present invention contains 3.0% or less of V. The austenitic non-magnetic steel of the present invention may or may not contain V, but since V improves strength by forming carbonitrides, it is desirable that the austenitic non-magnetic steel contain V. If the austenitic non-magnetic steel contains V, the V content may be greater than 0 mass%. On the other hand, if the V content exceeds 3.0%, excessive nitrides and the like are formed, reducing ductility, so the V content is set to 3.0% or less. When the austenitic non-magnetic steel contains V, the V content is preferably 0.5 to 2.5%, more preferably 0.5 to 2.0%, and even more preferably 0.7 to 1.5%.

[0017] The austenitic non-magnetic steel is austenitic. The non-magnetic steel becomes austenitic by containing the above-mentioned predetermined amounts of Mn and Cr.

[0018] The austenitic non-magnetic steel is a non-magnetic steel, which can be confirmed by measuring the relative magnetic permeability. The relative magnetic permeability is measured by a single sheet magnetic property test. Specifically, the relative magnetic permeability is measured using a micro single sheet magnetic measuring instrument that can perform measurements in accordance with JIS C 2556 on a sample processed into a shape of 10 mm x 60 mm x 1 mm. If the obtained relative permeability value is in the range of 1.00 to 1.02, it is determined to be non-magnetic.

[0019] The austenitic non-magnetic steel of the present invention may contain other elements in addition to the elements described above. The other elements are not particularly limited as long as they do not impair the effects of the present invention, and examples thereof include Mo. When the austenitic non-magnetic steel of the invention contains Mo, the Mo content is preferably 3.0 mass % or less, and more preferably 0.5 to 3.0 mass %.

[0020] The austenitic non-magnetic steel of the present invention preferably has the above chemical composition, with the balance being Fe and unavoidable impurities.

[0021] The inevitable impurities are components that may be inevitably mixed in from raw materials or the environment when producing the austenitic non-magnetic steel of the present invention, and examples thereof include Si, P, S, Cu, etc. The Si content is typically 1% by mass or less, the P and S contents are typically 0.1% by mass or less, and the Cu content is 0.5% by mass or less.

[0022] Since the austenitic non-magnetic steel of the present invention is non-magnetic, when it is applied to a motor or generator, it does not affect the efficiency of the motor or generator. The austenitic non-magnetic steel of the present invention has a high strength of 1500 MPa or more and excellent elongation, so when used in rotating parts, it enables faster rotation than conventional parts and enables motors and generators to be made smaller and lighter. Products with the above characteristics can be realized at relatively low cost and with low resource risk.

[0023] There are no particular limitations on the method for producing the austenitic non-magnetic steel of the present invention, but for example, it can be produced by additive manufacturing of austenitic powder metal for additive manufacturing. For the layered manufacturing, a known method can be used.

[0024] <Powder metal materials for additive manufacturing> The powder metal material for additive manufacturing of the present invention is In mass%, Mn: 8.0 to 15.0%, C: 0.20~1.00%, Cr: 2.0 to 15.0%, V: 3.0% or less, The powder metal material is made of austenitic non-magnetic steel containing Unless otherwise specified, the content of each alloying element is a mass value with the entire powder metal material for additive manufacturing being 100%.

[0025] The powdered metal material of the present invention contains 8.0 to 15.0% of Mn. Mn is an essential additive element for forming the powder metal material into an austenitic structure and making it nonmagnetic. Considering the synergistic effect with the simultaneously added C and N, an austenitic structure can be obtained if the Mn content is 8.0% or more. On the other hand, considering the stability of the austenitic structure, the saturation of strength, and the risk of ignition due to static electricity, the Mn content is preferably 15.0% or less. The Mn content is preferably 10.0 to 15.0%, and more preferably 10.0 to 12.0%.

[0026] The powdered metal material of the present invention contains C in an amount of 0.20 to 1.00%. C has the effect of solid solution strengthening the austenitic structure and increasing strength by forming carbides with Cr and V. To obtain these effects, the C content is set to 0.20% or more. On the other hand, if the C content exceeds 1.00%, the elongation of the resulting austenitic non-magnetic steel becomes small, so the C content is set to 1.00% or less. The C content is preferably 0.30 to 0.90%, and more preferably 0.30 to 0.40%.

[0027] The powdered metal material of the present invention contains 2.0 to 15.0% of Cr. Cr is effective in increasing the amount of nitrogen added to the resulting austenitic non-magnetic steel, improving strength by forming carbonitrides, and improving corrosion resistance. To achieve these effects, the Cr content is set to 2.0% or more. However, if the Cr content exceeds 15.0%, the strength saturates, so the Cr content is set to 15.0% or less. The Cr content is preferably 3.0 to 13.0%, more preferably 4.0 to 12.0%, and further preferably 5.0 to 11.0%.

[0028] The powdered metal material of the present invention contains V in an amount of 3.0% or less. The powder metal material of the present invention may or may not contain V, but since V improves strength by forming carbonitrides, it is desirable that the powder metal material contain V. When the powder metal material contains V, the V content may be greater than 0 mass%. On the other hand, if the V content exceeds 3.0%, excessive nitrides and the like are formed, reducing ductility, so the V content is set to 3.0% or less. When the powdered metal material contains V, the V content is preferably 0.5 to 2.5%, more preferably 0.5 to 2.0%, and even more preferably 0.7 to 1.5%.

[0029] The powder metal material of the present invention is In mass%, N: It may contain 0.05 to 0.5% or may not contain any, but the powder metal material of the present invention contains, in mass %, N: It is preferable that the content is 0.05 to 0.5%. The N content is preferably 0.10 to 0.50%, and more preferably 0.15 to 0.25%.

[0030] The powder metal material of the present invention may contain other elements in addition to the elements described above. The other elements are not particularly limited as long as they do not impair the effects of the present invention, and examples thereof include Mo. When the powdered metal material of the present invention contains Mo, the Mo content is preferably 3 mass % or less, more preferably 0.5 to 3.0 mass %.

[0031] The powdered metal material of the present invention preferably has the above chemical composition, with the balance being Fe and unavoidable impurities.

[0032] The inevitable impurities are components that may be unavoidably mixed in from raw materials or the environment when producing the powder metal material of the present invention, and examples thereof include Si, P, S, Cu, etc. The Si content is typically 1% by mass or less, the P and S contents are typically 0.1% by mass or less, and the Cu content is 0.5% by mass or less.

[0033] The particle size of the powder metal material of the present invention is not particularly limited, and can be any known particle size suitable for additive manufacturing using a 3D printer (for example, D10≧20 μm and D90≦65 μm in the wet laser diffraction method for powder bed fusion, or D10≧50 μm and D90≦120 μm in the directed energy deposition method).

[0034] The method for producing the powder metal material of the present invention is not particularly limited, and known methods (for example, gas atomization, water atomization, plasma atomization, plasma rotating electrode method, centrifugal atomization, etc.) can be used.

[0035] The powdered metal material of the present invention is non-magnetic steel, which can be confirmed by measuring the relative magnetic permeability. The relative magnetic permeability shall be measured by a single sheet magnetic property test. Specifically, a 10mm x 60mm x 1mm measurement piece shall be prepared from the molded body and measured using a micro single sheet magnetic measuring instrument capable of performing measurements in accordance with JIS C 2556. If the obtained relative permeability value is in the range of 1.00 to 1.02, it is determined to be non-magnetic.

[0036] <Method of manufacturing austenitic non-magnetic steel> The method for producing austenitic non-magnetic steel of the present invention includes a step (also referred to as step 1) of additively manufacturing the above-mentioned powder metal material. Specifically, step 1 is a step of using the powder metal material to form a shape using a 3D printer, thereby producing the austenitic non-magnetic steel. Process 1 is 3D printing, in which powder metal material is melted by irradiation with a laser or electron beam and then cooled to create a shape. A known 3D printer can be used. The method of additive manufacturing is not particularly limited, but for example, powder bed fusion, directed energy deposition, etc. are preferred. [Example]

[0037] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0038] (Examples 1 to 6, Comparative Examples 1 to 6) Powder metal materials (measured by wet laser diffraction method with D10 of 20 μm or more and 25 μm or less and D90 of 60 μm or more and 65 μm or less) having the compositions shown in Table 1 below were produced by gas atomization. The powdered metal material of Examples 1 to 6 in Table 1 was austenitic non-magnetic steel.

[0039] The powder metal materials of the examples and comparative examples in Table 1 were additively manufactured using a 3D printer to produce round bars with a diameter of 12 mm and a length of 80 mm. The modeling machine used was an EOS M290, and the modeling conditions were: power output 240 W, layer thickness 40 μm, scan speed 900 mm / s, hatch distance 0.1 mm, and preheating temperature at room temperature. The obtained round bars were then machined all over to produce test pieces.

[0040] <Measurement of relative permeability> The relative magnetic permeability is measured by a single sheet magnetic property test. The round bar product is machined on all sides to be processed into a 10 x 60 x 1 mm test piece, and the relative magnetic permeability is measured using a small single sheet magnetic property tester that can perform measurements in accordance with JIS C 2556. The results are shown in the "relative permeability" column of Table 1.

[0041] <Measurement of tensile strength> The entire surface of the round bar was machined to prepare test specimens. Tensile tests were carried out at room temperature at a tension rate of 5 mm / min using an autograph manufactured by Shimadzu Corporation. The tensile strength (MPa) was measured in accordance with JIS Z 2241, and the test specimen shape was a JIS No. 14A round bar test specimen. The results are shown in the "Tensile strength (MPa)" column of Table 1.

[0042] <Measurement of elongation> For the above test specimens, elongation was measured by measuring the change in gauge length during the above tensile strength measurement with an extensometer. The results are shown in the "Elongation (%)" column of Table 1.

[0043] [Table 1]

[0044] It can be seen from Table 1 that the powdered metal materials of Examples 1 to 6 make it possible to produce austenitic non-magnetic steels that are high in strength and excellent in elongation.

[0045] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. are possible as appropriate.

[0046] Furthermore, this specification describes at least the following:

[0047] (1) Austenitic non-magnetic steel, The non-magnetic steel comprises, in mass%, Mn: 8.0 to 15.0%, N: 0.05 to 0.50%, C: 0.20~1.00%, Cr: 2.0 to 15.0%, V:3.0% or less Austenitic non-magnetic steel containing

[0048] According to (1), it is possible to obtain austenitic non-magnetic steel with high strength and excellent elongation. In addition, it is possible to obtain a non-magnetic steel with a strength of 1500 MPa or more and excellent elongation, and it can be used, for example, by powder metal 3D printing additive manufacturing to produce non-magnetic steel parts (e.g., rotor bodies for rotating electrical machines) that require strength to withstand external forces.

[0049] (2) A powder metal material for additive manufacturing, The powder metal material comprises, in mass %, Mn: 8.0 to 15.0%, C: 0.20~1.00%, Cr: 2.0 to 15.0%, V: 3.0% or less, A powder metal material comprising an austenitic non-magnetic steel containing

[0050] According to (2), by using the above powder metal material and introducing nitrogen into the austenitic non-magnetic steel of (1), it is possible to manufacture the austenitic non-magnetic steel of (1), for example, by powder metal 3D printing additive manufacturing.

[0051] (3) In mass%, N: The powder metal material according to (2), containing 0.05 to 0.5%.

[0052] According to (3), it is possible to manufacture the austenitic non-magnetic steel of (1) using the above powder metal material, for example, by powder metal 3D printing additive manufacturing.

[0053] (4) A method for producing austenitic non-magnetic steel, comprising a step of additively manufacturing the powder metal material according to (2) or (3).

[0054] According to (4), it is possible to produce the austenitic non-magnetic steel of (1).

Claims

1. Austenitic non-magnetic steel, The non-magnetic steel comprises, in mass %, Mn: 8.0 to 15.0%, N: 0.05-0.50%, C: 0.20-1.00%, Cr: 2.0-15.0%, V: 3.0% or less, Mo: 3.0% or less, The balance is Fe and unavoidable impurities Austenitic non-magnetic steel consisting of

2. A powder metal material for additive manufacturing, comprising: The powder metal material contains, in mass %, Mn: 8.0 to 15.0%, N: 0.05-0.5%, C: 0.20-1.00%, Cr: 2.0-15.0%, V: 3.0% or less, Mo: 3% or less, The balance is Fe and unavoidable impurities A powder metal material comprising an austenitic non-magnetic steel.

3. A method for producing austenitic non-magnetic steel, comprising a step of additively manufacturing the powder metal material according to claim 2.

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