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WO2025170067A1 - Poudre d'acier pour outil de travail à chaud pour fabrication additive et article en acier pour outil de travail à chaud fabriqué par fabrication additive - Google Patents

Poudre d'acier pour outil de travail à chaud pour fabrication additive et article en acier pour outil de travail à chaud fabriqué par fabrication additive

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Publication number
WO2025170067A1
WO2025170067A1 PCT/JP2025/004210 JP2025004210W WO2025170067A1 WO 2025170067 A1 WO2025170067 A1 WO 2025170067A1 JP 2025004210 W JP2025004210 W JP 2025004210W WO 2025170067 A1 WO2025170067 A1 WO 2025170067A1
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WO
WIPO (PCT)
Prior art keywords
work tool
hot work
tool steel
additive manufacturing
additive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2025/004210
Other languages
English (en)
Japanese (ja)
Inventor
大樹 齋藤
範英 福澤
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Proterial Ltd
Original Assignee
Proterial Ltd
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Filing date
Publication date
Application filed by Proterial Ltd filed Critical Proterial Ltd
Publication of WO2025170067A1 publication Critical patent/WO2025170067A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y70/00—Materials specially adapted for additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y80/00—Products made by additive manufacturing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium

Definitions

  • the present invention relates to hot work tool steel powder for additive manufacturing and hot work tool steel additive manufactured products.
  • Hot work tool steels used in hot forging dies, die casting dies, and other tools come into contact with high-temperature workpieces, and therefore require high-temperature strength, toughness, and wear resistance.
  • JIS steel grade SKD61 and improved versions of SKD61 have been used for hot work tool steels.
  • additive manufacturing has been attracting attention as a means of easily creating near-net-shape metal products (components) with complex shapes.
  • Additive manufacturing commonly known as 3D printing, is an additive manufacturing technology.
  • Types of additive manufacturing include the powder spray method, in which a heat source is applied to metal powder to melt it and then layer it on top, and the powder bed method, in which a heat source is applied to metal powder spread on a stage to melt it, then the powder is solidified and layered repeatedly.
  • Additive manufacturing allows metal products with complex shapes to be produced without requiring much of the traditional machining process, making it possible to use metal materials that are difficult to process.
  • difficult-to-process metal materials are primarily high-strength metal materials, it is possible to produce metal products with complex shapes and long durability.
  • Patent Document 1 proposes an additively manufactured hot work tool having a component composition containing, by mass%, 0.3 to 0.5% C, 2.0% or less Si, 1.5% or less Mn, 0.05% or less P, 0.05% or less S, 3.0 to 6.0% Cr, 0.5 to 3.5% of one or two of Mo and W according to the relationship (Mo + 1/2W), 0.1 to 1.5% V, 0 to 1.0% Ni, 0 to 1.0% Co, 0 to 1.0% Nb, and the balance being Fe and impurities, and characterized in that the area ratio of defects having an area of 1 ⁇ m2 or more in a cross section parallel to the stacking direction is 0.6% or less.
  • Patent Document 2 discloses a steel powder that aims to achieve both high thermal conductivity and high corrosion resistance and is characterized by a composition, in mass%, of 0.10 ⁇ C ⁇ 0.25, 0.005 ⁇ Si ⁇ 0.600, 2.00 ⁇ Cr ⁇ 6.00, -0.0125 ⁇ [Cr]+0.125 ⁇ Mn ⁇ -0.100 ⁇ [Cr]+1.800...formula (a) (wherein [Cr] in formula (a) represents the mass % Cr content), 0.01 ⁇ Mo ⁇ 1.80, -0.00447 ⁇ [Mo]+0.010 ⁇ V ⁇ -0.1117 ⁇ [Mo]+0.901...formula (b) (wherein [Mo] in formula (b) represents the mass % Mo content), 0.0002 ⁇ N ⁇ 0.3000, with the balance being Fe and unavoidable impurities.
  • Another aspect of the present invention is a hot work tool steel additive manufactured product that contains, in mass%, 0.10% ⁇ C ⁇ 0.40%, 0.01% ⁇ Si ⁇ 0.19%, 0.1% ⁇ Mn ⁇ 1.0%, 2.0% ⁇ Ni ⁇ 9.0%, 3.5% ⁇ Cr ⁇ 4.5%, one or two of Mo and W according to the relationship (Mo+1/2W): 2.5% ⁇ (Mo+1/2W) ⁇ 3.5%, 0.45% ⁇ V ⁇ 1.0%, 0.3% ⁇ Cu ⁇ 0.6%, 0.2% ⁇ Al ⁇ 0.9%, with the balance being Fe and unavoidable impurities, and that satisfies formula (1): C+Si/30+(Mn+Cr+Cu)/20+Ni/60+(Mo+1/2W)/15+V/10 ⁇ 0.95.
  • the present invention makes it possible to obtain hot work tool steel powder for additive manufacturing, which can be used to produce hot work tool steel additive manufactured products that have particularly excellent crack resistance during additive manufacturing.
  • FIG. 1 is a schematic diagram of a crack evaluation test piece for evaluating molding crack resistance.
  • 1 is a graph showing the tempering temperature and hardness of hot work tool steel additive manufactured products of an example of the present invention and a comparative example.
  • 1 is a graph showing the mechanical properties ((a) 0.2% proof stress, (b) tensile strength, (c) elongation, (d) reduction of area) of an example of the present invention at room temperature.
  • 1 is a graph showing the mechanical properties ((a) 0.2% yield strength, (b) tensile strength, (c) elongation, (d) reduction of area) of an example of the present invention at high temperatures.
  • 1 is a graph showing Charpy impact values at room temperature of examples of the present invention.
  • 1 is a graph showing the thermal conductivity of an example of the present invention.
  • the present invention has a chemical composition consisting of 0.10% ⁇ C ⁇ 0.40%, 0.01% ⁇ Si ⁇ 0.19%, 0.1% ⁇ Mn ⁇ 1.0%, 2.0% ⁇ Ni ⁇ 9.0%, 3.5% ⁇ Cr ⁇ 4.5%, one or two of Mo and W according to the relationship (Mo+1 ⁇ 2W): 2.5% ⁇ (Mo+1 ⁇ 2W) ⁇ 3.5%, 0.45% ⁇ V ⁇ 1.0%, 0.3% ⁇ Cu ⁇ 0.6%, 0.2% ⁇ Al ⁇ 0.9%, and the balance being Fe and unavoidable impurities.
  • Mo+1 ⁇ 2W 2.5% ⁇ (Mo+1 ⁇ 2W) ⁇ 3.5%, 0.45% ⁇ V ⁇ 1.0%, 0.3% ⁇ Cu ⁇ 0.6%, 0.2% ⁇ Al ⁇ 0.9%
  • C 0.10% ⁇ C ⁇ 0.40%
  • Carbon (C) is a fundamental element of hot-working tools, partially dissolving in the matrix to provide strength, while partially forming carbides to enhance wear resistance and seizure resistance. Furthermore, when added together with substitutional atoms with high affinity for C, such as Cr, C dissolved as an interstitial atom is expected to contribute to the I (interstitial atom)-S (substitutional atom) effect (which acts as drag resistance for solute atoms and increases the strength of hot-working tools). It also has the potential to enhance hardenability.
  • the C content is set to 0.10% ⁇ C ⁇ 0.40% in order to improve crack resistance while maintaining hardness sufficient for use in dies.
  • the preferred lower limit of C is 0.15% or more, more preferably 0.18% or more, even more preferably 0.20% or more, and 0.21% or more.
  • the preferred upper limit of C is 0.35% or less, more preferably 0.30% or less, even more preferably 0.27% or less, 0.25% or less, and 0.24% or less.
  • Si 0.01% ⁇ Si ⁇ 0.19% Silicon can be used as a deoxidizer when adjusting the chemical composition of molten steel. It is difficult to eliminate silicon from the manufacturing process. Furthermore, the closer one tries to eliminate silicon, the higher the manufacturing cost. Therefore, the lower limit of silicon content is set to 0.01% or more. A preferred lower limit is 0.05% or more, and more preferably 0.08% or more. On the other hand, excessive silicon content can lead to the formation of ferrite in the tool structure after tempering, so the upper limit is set to 0.19% or less. A preferred upper limit is 0.17% or less, and more preferably 0.15% or less, and even 0.13% or less.
  • Mn 0.1% ⁇ Mn ⁇ 1.0% Mn has the effects of improving hardenability, suppressing the formation of ferrite in the tool structure, and achieving appropriate quench-and-temper hardness.
  • the lower limit of Mn is set to 0.1% or more.
  • a preferred lower limit is 0.25%, and more preferably 0.40% or more.
  • the upper limit is set to 1.0% or less.
  • a preferred upper limit is 0.7% or less, more preferably 0.6% or less, and even more preferably 0.55% or less.
  • Ni 2.0% ⁇ Ni ⁇ 9.0%
  • Ni is an element that suppresses the formation of ferrite in the tool structure.
  • C, Cr, Mn, Mo, W, etc. it imparts excellent hardenability to tool materials and is an effective element for preventing a decrease in toughness by forming a martensite-based structure even when the cooling rate during quenching is slow.
  • it can lower the Ms point.
  • the temperature during manufacturing may be close to room temperature depending on the manufacturing conditions.
  • the effect of mitigating thermal contraction due to martensitic transformation expansion can be utilized, thereby reducing deformation due to thermal contraction.
  • the lower limit of Ni is set to 2.0%.
  • a preferred lower limit is 4.0%. It is more preferably 5.0% or more, and even more preferably 6.0% or more, 7.0% or more, or 7.5% or more.
  • the upper limit is set to 9.0%.
  • the preferred upper limit is 8.5%.
  • a particularly preferred Ni range is 7.5 to 8.5%.
  • a particularly preferred Ni range is 3.5 to 4.5%.
  • a particularly preferred Ni range is 5.5 to 6.5%.
  • V 0.45% ⁇ V ⁇ 1.0%
  • V forms vanadium carbides, which strengthen the matrix and improve its wear resistance and temper softening resistance.
  • the vanadium carbides also function as "pinning particles" that suppress coarsening of austenite grains during quenching, contributing to improved toughness.
  • V has a high carbide-forming ability, excessive V may convert all C to vanadium carbide, preventing the formation of other carbides.
  • Tool steels are made up of multiple types of carbides, so vanadium carbide alone is not desirable. Therefore, the V content is 0.45% or less and 1.0% or less.
  • the preferred lower limit is 0.50%, more preferably 0.52% or more and 0.55% or more.
  • the preferred upper limit is 0.80%, more preferably 0.70% or less, 0.67% or less, and 0.65% or less.
  • Cu 0.3% ⁇ Cu ⁇ 0.6%
  • Cu is an element that suppresses the formation of ferrite in the tool structure. It also effectively imparts excellent hardenability to tool materials, along with C, Cr, Mn, Ni, Mo, W, etc., and forms a martensite-based structure even when the cooling rate during quenching is slow, thereby preventing a decrease in toughness.
  • Cu is set to more than 0.3% (0.3% ⁇ Cu). Preferably, it is set to 0.35% or more.
  • excessive addition of Cu precipitates as a simple element in Fe, reducing toughness. Therefore, Cu is set to less than 1.0% (Cu ⁇ 0.6%).
  • Cu is set to 0.45% or less, and 0.42% or less.
  • Al 0.2% ⁇ Al ⁇ 0.9%
  • Al is an element that forms intermetallic compounds such as Ni3Al with Ni and has the effect of precipitation strengthening the metal structure. Since Ni is added in the present invention, adding Al can improve hardness. Therefore, the lower limit of Al is set to 0.2%. A preferred lower limit is 0.3%, and more preferably 0.4% or more. However, if the amount of Al is too much, non-metallic inclusions may increase in the metal structure, reducing toughness. Therefore, the upper limit of Al is set to 0.9%. A preferred upper limit is 0.8% or less, more preferably 0.7% or less, and even more preferably 0.6% or less.
  • the balance consists of Fe and unavoidable impurities.
  • Typical examples of unavoidable impurities include elements such as P, S, Ca, Mg, O (oxygen), N (nitrogen), and B (boron). The lowest possible content of these elements is preferable. However, small amounts may be included due to additional effects such as controlling the shape of inclusions, improving other mechanical properties, and improving manufacturing efficiency. In this case, the ranges of Ca ⁇ 0.01%, Mg ⁇ 0.01%, O ⁇ 0.05%, N ⁇ 0.05%, and B ⁇ 0.05% are sufficient and are the preferred upper limits of the present invention.
  • P and S can conform to the JIS steel grade SKD61, e.g., P ⁇ 0.030% and S ⁇ 0.020%.
  • Formula (1) C+Si/30+(Mn+Cr+Cu)/20+Ni/60+(Mo+1/2W)/15+V/10 ⁇ 0.95
  • the left side of formula (1) is an improved version of Pcm, which is used as a cold cracking susceptibility index for welding.
  • C, Si, Mn, Cr, Cu, Ni, Mo, W, and V in formula (1) represent the content (mass%) of each element.
  • cracking is a problem in welding, and both are molten solidification structures. Therefore, it was found that this index can be applied to suppress cracking in additive manufacturing, and was applied to the present invention.
  • the hot cracking index HCS Another known cracking index for welding is the hot cracking index HCS.
  • HCS hot cracking index
  • prior investigations revealed that the molding cracks in this composition system were largely cracked from the surface and had a different morphology from the hot cracks that tend to occur at the solidification interface, etc. Since the molding cracks in this composition system are found in areas prone to tensile stress due to thermal contraction and therefore occur at low temperatures, it was assumed that they were similar to cold cracks in welding. Therefore, the cold cracking index Pcm was applied in the present invention.
  • the left side of formula (1) is more preferably 0.92 or less, and even more preferably 0.90 or less.
  • Formula (2) 545-330C+2Al-14Cr-13Cu-23Mn-5Mo-4Nb-13Ni-7Si+3Ti+4V ⁇ 400
  • the above formula (2) can be adjusted to 400 or less.
  • Formula (2) is a relationship between elements and Ms point disclosed in a literature (K. Ishida, Journal of Alloys and Compounds, Volume 220, Issues 1-2, 1995, pp. 126-131). It is expected that a high value of formula (2) will result in a high Ms point, which will tend to transform into brittle martensite at high temperatures during additive manufacturing and become more susceptible to cracking due to thermal contraction when cooled to room temperature.
  • Formula (2) is preferably 380 or less, more preferably 360 or less, even more preferably 340 or less, particularly preferably 320 or less, and extremely preferably 300 or less.
  • the lower limit of formula (2) is not particularly limited, if the value of formula (2) is too low, it is expected that the Ms point will be low. If the value is too low, martensitic transformation will not be completed, and austenite will remain, which may result in a decrease in strength. Therefore, it is preferable to adjust formula (2) to 200 or more. It is more preferably 220 or more, and even more preferably 240 or more, or 260 or more.
  • the hot work tool steel powder for additive manufacturing of the present invention preferably has a 50% particle size (hereinafter referred to as "D50") of a cumulative particle size distribution on a volume basis of 10 to 250 ⁇ m.
  • D50 50% particle size
  • the cumulative particle size distribution of the powder for layered manufacturing of the present invention is expressed as a cumulative volumetric particle size distribution, and its D50 can be expressed as a value measured by the laser diffraction scattering method specified in JIS Z 8825.
  • the hot work tool steel additive manufactured product of the present invention preferably has a room temperature (approximately 20°C) tensile strength of 500 to 2000 MPa when the tempered hardness is adjusted to 45 HRC ⁇ 2.
  • a more preferable lower limit is 1000 MPa, and an even more preferable lower limit is 1200 MPa.
  • the room temperature 0.2% proof stress when the tempered hardness is adjusted to 45 HRC ⁇ 2 is preferably 500 to 2000 MPa.
  • a more preferable lower limit is 800 MPa, an even more preferable lower limit is 1000 MPa, and an even more preferable lower limit is 1100 MPa.
  • the room temperature elongation when the tempered hardness is adjusted to 45 HRC ⁇ 2 is preferably 5% or more.
  • a more preferable lower limit is 8% and an even more preferable lower limit is 10%.
  • the room temperature drawing when the tempered hardness is adjusted to 45 HRC ⁇ 2 is preferably 20% or more.
  • a more preferable lower limit is 30%, and an even more preferable lower limit is 40%.
  • the room temperature 2 mm U-notch Charpy impact value is preferably 20 J/ cm2 or more.
  • a more preferable lower limit is 30 J/ cm2 , and an even more preferable lower limit is 40 J/ cm2 .
  • the hot work tool steel additive manufactured product of the present invention preferably has a high-temperature (approximately 550°C in this embodiment) tensile strength of 400 to 1500 MPa when the tempered hardness is adjusted to 45HRC ⁇ 2.
  • a more preferred lower limit is 500 MPa, and an even more preferred lower limit is 600 MPa.
  • the high-temperature 0.2% yield strength when the tempered hardness is adjusted to 45HRC ⁇ 2 is preferably 300 to 1300 MPa.
  • a more preferred lower limit is 400 MPa, and an even more preferred lower limit is 500 MPa.
  • the high-temperature elongation when the tempered hardness is adjusted to 45HRC ⁇ 2 is preferably 5% or more.
  • a more preferred lower limit is 8%, and an even more preferred lower limit is 10%.
  • the high-temperature reduction when the tempered hardness is adjusted to 45HRC ⁇ 2 is preferably 10% or more.
  • a more preferred lower limit is 20%, and an even more preferred lower limit is 30%.
  • the room temperature thermal conductivity of the hot work tool steel additive manufactured product of the present invention, when the tempered hardness is adjusted to 45HRC ⁇ 2, is preferably 5 W/(m ⁇ K) or more.
  • a more preferred lower limit is 10 W/(m ⁇ K), and an even more preferred lower limit is 15 W/(m ⁇ K).
  • the additively manufactured product of the present invention is most preferably applied to die-casting molds, but it may also be applied to other molds that require internal cooling mechanisms, such as plastic molds. It may also be applied to repairing molds that have been manufactured using the powder spray additive manufacturing method.
  • a manufacturing process for obtaining an additive manufactured product of the present invention using the hot working tool steel powder for additive manufacturing of the present invention will be described in order. Note that the manufacturing process described below is based on the powder bed method unless otherwise specified.
  • the manufacturing method of the present invention involves the steps of spreading the prepared hot work tool steel powder for additive manufacturing of the present invention in layers, and sequentially melting and solidifying the spread metal powder using a scanning heat source having a diameter larger than the D50 of the metal powder to form solidified layers.
  • the step of spreading the metal powder in layers and the step of forming the solidified layers are then repeated to form multiple solidified layers, thereby producing the additively manufactured product of the present invention.
  • the scanning heat source may be, for example, a laser or electron beam. Setting the diameter of the scanning heat source to be larger than the D50 of the metal powder is preferable because it allows the metal powder clusters to be melted evenly.
  • the laser output can be set to 50 to 400 W, the scanning speed to 200 to 2000 mm/sec, and the scanning pitch to 0.02 to 0.20 mm.
  • the layer thickness per laser scan is too large, heat is not easily transferred to the entire spread metal powder during laser irradiation, preventing the metal powder from melting sufficiently and promoting the formation of internal defects.
  • the layer thickness per scan is preferably set to 10 to 200 ⁇ m.
  • a more preferable lower limit for the layer thickness is 20 ⁇ m, and a more preferable upper limit for the layer thickness is 100 ⁇ m.
  • a preheating step may be carried out before the additive manufacturing process described above. However, because the powder of the present invention has improved crack resistance compared to conventional hot work tool steel powders, for example, if the additive manufacturing product is small and has few stress concentration areas, it is possible to omit the preheating step before additive manufacturing or to use a lower temperature.
  • the as-AM i.e., the AM product without heat treatment after AM
  • a tempering treatment at a temperature of 500 to 700°C.
  • Tempering can produce a "hot work tool steel AM product" with a predetermined hardness.
  • the AM product can be shaped into the shape of a hot work tool by various machining processes such as cutting and drilling.
  • the AM product formed in the AM process can be annealed to facilitate machining. Annealing can also be expected to refine the vanadium carbide in the structure of the tempered AM hot work tool. Finishing machining can then be performed after tempering.
  • this finishing machining can also be performed on the tempered AM product, and the above-mentioned machining processes can be performed all at once to produce an AM hot work tool. It should be noted that quenching can be performed before the above-mentioned tempering. Regardless of whether or not the above-mentioned annealing is performed, the additive manufacturing product formed in the additive manufacturing process can be subjected to normalizing.
  • the tempering temperature varies depending on the target hardness, etc., but is generally around 500 to 700°C. If quenching is performed before tempering, the quenching temperature is generally around 900 to 1100°C. For example, in the case of SKD61, a typical hot work tool steel, the quenching temperature is around 1000 to 1030°C, and the tempering temperature is around 550 to 650°C.
  • the tempered hardness is preferably 50 HRC (Rockwell hardness) or less or 520 HV (Vickers hardness) or less. More preferably, it is 48 HRC or less or 500 HV or less. Also, it is preferably 40 HRC or more or 380 HV or more. More preferably, it is 42 HRC or more or 400 HV or more.
  • the hardness can be measured in accordance with the measurement method described in JIS Z 2245 "Rockwell hardness test - Test method” or JIS Z 2244-1 "Vickers hardness test - Part 1: Test method", and Rockwell C scale hardness (HRC) or Vickers hardness (HV) can be used.
  • Example 1 Each metal raw material was prepared to have the component composition shown in Table 1, then charged into a high-frequency induction melting furnace and melted. The molten metal was pulverized with argon gas to obtain gas-atomized powder. The resulting atomized powder was subjected to mesh sieving and airflow classification to adjust the particle size, resulting in additive manufacturing powders for the present invention and comparative examples with a D50 of 35 ⁇ m. Additive manufacturing products were produced using the additive manufacturing powders obtained above using an EOS M290 under the manufacturing conditions shown in Table 2. Table 3 shows the component compositions of the additive manufacturing products of Sample No. 5 produced from powder No. 1, Sample No. 6 produced from powder No. 2, Sample No. 7 produced from powder No. 3, and Sample No. 8 produced from powder No. 4.
  • Table 4 also shows the component compositions of Sample No. 1, Sample No. 6 produced from powder No. 2, Sample No. 7 produced from powder No. 3, and Sample No. 8 produced from powder No. 4.
  • This stress concentration area was comb-shaped to facilitate cracking, and was designed to simulate an additive manufacturing mold for forming complex cavities. After fabrication, the crack length of the comb-tooth portion of these crack evaluation test pieces was measured, allowing the susceptibility of the material to crack during fabrication to be evaluated.
  • Sample No. The crack lengths of the crack test pieces for Samples No. 9, 11, and 12 (Invention Examples) and Sample No. 10 (Comparative Example) are shown in Table 5. From Table 5, it was confirmed that the Inventive Examples had significantly shorter crack lengths than the Comparative Examples, and had particularly superior crack resistance during molding compared to the Comparative Examples. In particular, Sample No. 9 had a crack length of 1.0 mm or less, confirming that it had the best crack resistance.
  • Example 3 Next, the tempering behavior of the inventive and comparative examples was confirmed. Samples Nos. 5 to 8 shown in Example 1 above were subjected to tempering heat treatment within the temperature range shown in Figure 2, and their Rockwell hardness was measured in accordance with JIS Z 2245. Figure 2 shows a graph of each tempering temperature and hardness. From Figure 2, it was confirmed that inventive samples Nos. 5, 7, and 8 could be tempered to a higher hardness than comparative sample No. 6.
  • the additive manufactured products of the examples of the present invention had room temperature tensile strength of 1100 MPa or more, room temperature 0.2% proof stress of 600 MPa or more, room temperature elongation of 12% or more, and room temperature drawing of 50% or more at all tempered hardnesses. Also, as shown in Fig. 4, the additive manufactured products of the examples of the present invention had high temperature tensile strength of 700 MPa or more, high temperature 0.2% proof stress of 400 MPa or more, high temperature elongation of 13% or more, and high temperature drawing of 35% or more at all tempered hardnesses.
  • the additive manufactured products of the examples of the present invention had a room temperature tensile strength of 1200 MPa or more, a room temperature 0.2% proof stress of 1100 MPa or more, a room temperature elongation of 13% or more, and a room temperature drawing capacity of 50% or more at a hardness of 45 ⁇ 2 HRC.
  • the additive manufactured products of the examples of the present invention had a high temperature tensile strength of 800 MPa or more, a high temperature 0.2% proof stress of 500 MPa or more, a high temperature elongation of 15% or more, and a high temperature drawing capacity of 35% or more at a hardness of 45 ⁇ 2 HRC.
  • Figure 5 confirms that the additively manufactured products of the present invention have a Charpy impact value of 50 J/ cm2 or higher at all tempered hardness levels.
  • Figure 6 also confirms that the additively manufactured products of the present invention have a thermal conductivity of 15 W/(m K) or higher at room temperature.
  • sample No. 7 had a thermal conductivity of 20 W/(m K) or higher at room temperature, demonstrating the best thermal conductivity characteristics.
  • the additively manufactured product of the present invention has properties at the same level as those of ingot hot work tool steel, and is suitable for use in hot work tools, for example.

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  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Plasma & Fusion (AREA)
  • Powder Metallurgy (AREA)

Abstract

La présente invention concerne une poudre d'acier pour outil de travail à chaud pour la fabrication additive, avec laquelle il est possible de former un article en acier pour outil de travail à chaud fabriqué par fabrication additive qui est particulièrement excellent en termes de résistance à la fissuration pendant la fabrication.　L'invention concerne : une poudre d'acier pour outil de travail à chaud pour la fabrication additive, qui contient, en % en masse, 0,10 % ≤ C ≤ 0,40 %, 0,01 % ≤ Si ≤ 0,19 %, 0,1 % ≤ Mn ≤ 1,0 %, 2,0 % ≤ Ni < 9,0 %, 3,5 % < Cr < 4,5 %, Mo et/ou W satisfaisant une expression relationnelle 2,5 % ≤ (Mo + 1/2 W) < 3,5 %, 0,45 % ≤ V ≤ 1,0 %, 0,3 % < Cu < 0,6 %, et 0,2 % ≤ Al ≤ 0,9 %, le reste étant constitué de Fe et d'impuretés inévitables, et qui satisfait à la formule (1) C + Si/30 + (Mn + Cr + Cu) /20 + Ni / 60 + (Mo + 1 / 2W) / 15 + V / 10 ≤ 0,95 ; et un article en acier pour outil de travail à chaud fabriqué par fabrication additive.
PCT/JP2025/004210 2024-02-09 2025-02-07 Poudre d'acier pour outil de travail à chaud pour fabrication additive et article en acier pour outil de travail à chaud fabriqué par fabrication additive Pending WO2025170067A1 (fr)

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JP2024-018386 2024-02-09
JP2024018386 2024-02-09
JP2024148046 2024-08-29
JP2024-148046 2024-08-29

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WO2025170067A1 true WO2025170067A1 (fr) 2025-08-14

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001214238A (ja) * 2000-01-28 2001-08-07 Hitachi Metals Ltd 耐ヒートクラック性、耐摩耗性に優れる粉末熱間工具鋼および熱間金型
JP2008308745A (ja) * 2007-06-15 2008-12-25 Daido Steel Co Ltd 熱間鍛造金型及びその製造方法
JP2009504922A (ja) * 2005-08-18 2009-02-05 エラスティール クロスター アクチボラグ 粉末冶金製造された鋼、その鋼を含む工具、およびその工具の製造方法
JP2021127486A (ja) * 2020-02-13 2021-09-02 山陽特殊製鋼株式会社 製造性及び熱伝導率に優れる熱間工具鋼
JP2022072078A (ja) * 2020-10-29 2022-05-17 大同特殊鋼株式会社 金属粉末

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001214238A (ja) * 2000-01-28 2001-08-07 Hitachi Metals Ltd 耐ヒートクラック性、耐摩耗性に優れる粉末熱間工具鋼および熱間金型
JP2009504922A (ja) * 2005-08-18 2009-02-05 エラスティール クロスター アクチボラグ 粉末冶金製造された鋼、その鋼を含む工具、およびその工具の製造方法
JP2008308745A (ja) * 2007-06-15 2008-12-25 Daido Steel Co Ltd 熱間鍛造金型及びその製造方法
JP2021127486A (ja) * 2020-02-13 2021-09-02 山陽特殊製鋼株式会社 製造性及び熱伝導率に優れる熱間工具鋼
JP2022072078A (ja) * 2020-10-29 2022-05-17 大同特殊鋼株式会社 金属粉末

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