WO2021187484A1 - Acier pour matrice de formage à chaud, matrice pour formage à chaud et son procédé de fabrication - Google Patents

Acier pour matrice de formage à chaud, matrice pour formage à chaud et son procédé de fabrication Download PDF

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WO2021187484A1
WO2021187484A1 PCT/JP2021/010616 JP2021010616W WO2021187484A1 WO 2021187484 A1 WO2021187484 A1 WO 2021187484A1 JP 2021010616 W JP2021010616 W JP 2021010616W WO 2021187484 A1 WO2021187484 A1 WO 2021187484A1
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mold
hardness
steel
hot working
die
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PCT/JP2021/010616
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English (en)
Japanese (ja)
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修司 山中
貴之 平重
志保 福元
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日立金属株式会社
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Priority to EP21772321.2A priority Critical patent/EP4123047A1/fr
Priority to US17/911,411 priority patent/US20230099300A1/en
Priority to KR1020227031729A priority patent/KR20220143067A/ko
Priority to CN202180020353.6A priority patent/CN115279932B/zh
Publication of WO2021187484A1 publication Critical patent/WO2021187484A1/fr

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    • 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
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D37/00—Tools as parts of machines covered by this subclass
    • B21D37/10—Die sets; Pillar guides
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/06—Surface hardening
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0257—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment with diffusion of elements, e.g. decarburising, nitriding
    • 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
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • 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
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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 steel for hot working dies, hot working dies, and a method for manufacturing the same.
  • An advantage of the hot stamping method is that a molded product of an ultra-high-strength steel plate having a tensile strength of about 1.5 GPa can be obtained by quenching by die quenching in which the mold is rapidly cooled. Another advantage is that it has excellent moldability, such as almost no springback.
  • the hot stamping method has a problem of low productivity. That is, since it takes time to maintain the bottom dead center for diquenching, the productivity is lowered.
  • a mold with high thermal conductivity is required. This is because in diquenching, the heat of the steel sheet is absorbed by the mold, but the higher the thermal conductivity of the mold, the shorter the time for holding the bottom dead point and the higher the productivity.
  • hot stamping dies are required to have high hardness in order to improve wear resistance, and hot stamping die steel must have both high hardness and high thermal conductivity when made into a die. Is required.
  • Patent Document 1 and Patent Document 2 propose a composition of a mold steel having both hardness and thermal conductivity.
  • Patent Document 3 and Patent Document 4 are also useful as a material for dies used for hot pressing, die casting, hot forging, etc., and have excellent thermal conductivity and wear resistance. It is disclosed about tool steel.
  • Japanese Unexamined Patent Publication No. 2017-43814 Japanese Unexamined Patent Publication No. 2018-24931 Japanese Patent No. 5744300 JP-A-2017-53023
  • Patent Documents 1 and 2 and the hot tool steels of Patent Documents 3 and 4 are useful inventions capable of increasing hardness and thermal conductivity.
  • conventional mold steel and In the case of hot tool steel the hardness may be insufficient.
  • Patent Documents 1 to 3 indicate that a high hardness of 52 HRC or higher is stable. I can't get it.
  • the tempering temperature at which the maximum hardness of the mold steel can be obtained is generally around 575 ° C., but if the maximum hardness of the mold steel is less than 52 HRC, due to nitriding treatment or temperature rise during use, The hardness of the mold is further reduced from less than 52 HRC.
  • An object of the present invention is a die steel for hot working, which has a hardness and a thermal conductivity at a higher level than before, and can produce a die in which the hardness is maintained, and a steel for hot working. It is to provide a mold and a method for manufacturing the same.
  • the present inventor has found a component composition capable of controlling the amount of alloy, achieving high hardness and high thermal conductivity, and maintaining the achieved high hardness (that is, having a large softening resistance).
  • the steel for hot working dies of the present invention has been reached. Then, by using the above-mentioned steel for dies, a mold for hot working, which can achieve high hardness and high thermal conductivity and has excellent softening resistance, and a manufacturing method thereof have been found.
  • one aspect of the present invention is, in terms of mass%, C: 0.45 to 0.65%, Si: 0.1 to 0.6%, Mn: 0.1 to 2.5%, Cr: 1. 0 to 6.0%, Mo and W alone or in combination (Mo + 1 / 2W): 1.2 to 3.5%, V: 0.1 to 0.5%, Ni: 0.15 to 0.6 %, Cu: 0.1 to 0.6%, Al: 0.1 to 0.6% or less, and a steel for hot working molds having a component composition of the balance Fe and unavoidable impurities.
  • the hardness is 52 HRC or higher.
  • Another aspect of the present invention is, in mass%, C: 0.45 to 0.65%, Si: 0.1 to 0.6%, Mn: 0.1 to 2.5%, Cr: 1. 0 to 6.0%, Mo and W alone or in combination (Mo + 1 / 2W): 1.2 to 3.5%, V: 0.1 to 0.5%, Ni: 0.15 to 0.6 %, Cu: 0.1 to 0.6%, Al: 0.1 to 0.6% or less, and a hot working mold having a component composition of the balance Fe and unavoidable impurities.
  • the hardness is 52 HRC or more and the thermal conductivity is 25 W / (m ⁇ K) or more.
  • the working surface has a nitride layer.
  • Another aspect of the present invention is for hot working, wherein the above-mentioned steel for a hot working die is hardened and tempered at a quenching temperature of 1020 to 1080 ° C. and a tempering temperature of 540 to 620 ° C.
  • This is a mold manufacturing method.
  • the working surface is further subjected to nitriding treatment.
  • the optimum mold steel for hot working can be obtained. Further, by using this die steel, it is possible to provide a die for hot working, which has both high hardness and high thermal conductivity and maintains the high hardness, and a method for manufacturing the same.
  • FIG. 5 is a graph showing the thermal conductivity of the mold steels of the examples of the present invention and the comparative examples after being hardened and tempered to a hardness of 45 to 52 HRC.
  • the feature of the present invention is that the hot working die is manufactured by quenching and tempering the die steel, or by performing nitriding treatment on the working surface thereof. It has been found that there is an optimum composition of steel for dies to simultaneously achieve high hardness and high thermal conductivity of dies for quenching. In particular, it has been found that there is an optimum component for simultaneously achieving a high hardness of 52 HRC or higher and a high thermal conductivity of 25 W / (m ⁇ K) or higher. Further, in the composition of the optimum die steel, the optimum quenching and tempering conditions for achieving high hardness and high thermal conductivity at the same time have been identified. In particular, by setting the tempering temperature in the temperature range of 540 to 620 ° C.
  • the mold steel of the present invention having the optimum composition can achieve a high hardness of 52 HRC or more.
  • the mold is difficult to soften (the degree of softening is small) even in a temperature rising environment during treatment or use.
  • the hot working die of the present invention can be applied to, for example, a hot forging die, a die casting die, a hot extrusion die, and a hot stamping die, and particularly for a hot stamping die. It is preferable to apply.
  • a hot forging die a die casting die, a hot extrusion die, and a hot stamping die, and particularly for a hot stamping die. It is preferable to apply.
  • the steel for hot working dies of the present invention has a mass% (hereinafter, simply referred to as "%"), C: 0.45 to 0.65%, Si: 0.1 to 0.6%. , Mn: 0.1 to 2.5%, Cr: 1.0 to 6.0%, Mo and W alone or in combination (Mo + 1 / 2W): 1.2 to 3.5%, V: 0. 1 to 0.5%, Ni: 0.15 to 0.6%, Cu: 0.1 to 0.6%, Al: 0.1 to 0.6%, balance Fe and unavoidable impurity composition Have.
  • C is an element that is solid-solved in the substrate (matrix) by quenching to improve the hardness of the mold. Further, it is an element that improves the hardness of the mold by forming carbides with carbide-forming elements such as Cr, Mo, and V, which will be described later.
  • C is set to 0.45 to 0.65%. It is preferably 0.47% or more. More preferably, it is 0.49% or more. Further, it is preferably 0.63% or less. More preferably, it is 0.60% or less. More preferably, it is 0.58% or less.
  • Si 0.1-0.6%
  • Si is used as a deoxidizer in the melting process. It is an element that dissolves in the substrate to improve the hardness of the mold. However, if the amount of Si is too large, the segregation tendency in the steel becomes stronger after melting, and the solidified structure becomes coarse, which leads to a decrease in the toughness of the mold. It is an element that significantly lowers the thermal conductivity of the mold after quenching and tempering. Therefore, Si is set to 0.1 to 0.6%. It is preferably 0.14% or more. More preferably, it is 0.17% or more. Further, it is preferably 0.45% or less, and more preferably 0.4% or less. More preferably, it is 0.35% or less. Even more preferably, it is 0.3% or less.
  • Mn is used as a deoxidizing agent or a desulfurizing agent in the melting process. It is an element that contributes to strengthening the substrate and improving hardenability and toughness after quenching and tempering. However, if the amount of Mn is too large, the thermal conductivity of the mold is significantly lowered. Therefore, Mn is set to 0.1 to 2.5%. It is preferably 0.15% or more. Further, it is preferably 1.0% or less. More preferably, it is 0.35% or less. More preferably, it is 0.32% or less. Even more preferably, it is 0.3% or less.
  • Cr is an element that dissolves in the substrate to increase its hardness. It is also an element that increases hardness by forming carbides, and like Mo and V described later, it is an element that contributes to secondary curing during tempering.
  • Cr is an element that can increase the tempering softening resistance as compared with Mo and V (even if the tempering temperature is raised, the rate of decrease in hardness obtained by secondary curing can be reduced). be.
  • the mold is adjusted to the working hardness by quenching and tempering the mold steel, but in order to increase the thermal conductivity of the hot working mold, it is effective to raise the tempering temperature. Is.
  • the Cr content by setting the Cr content to 1.0% or more, a hardness of 52 HRC or more can be achieved even when the tempering temperature is high, and the thermal conductivity is 25 W / (m ⁇ K).
  • the above hot working dies can be obtained. Then, while maintaining the above hardness, it is also possible to obtain a hot working die in which the thermal conductivity is further improved to 28 W / (m ⁇ K) or more.
  • the above hardness and thermal conductivity are values measured at room temperature (normal temperature).
  • the nitriding characteristics of the mold steel can be improved. Therefore, for example, the working surface of the mold after quenching and tempering can be further nitrided to soften resistance. It is possible to improve the abrasion resistance (hardness of the work surface) of the mold while maintaining the hardness of the mold by improving the above.
  • Cr is set to 1.0 to 6.0%. It is preferably 1.5% or more. More preferably, it is 2.0% or more. Further, it is preferably 5.5% or less, more preferably 4.8% or less, still more preferably less than 4.5%. Then, when it is particularly important to improve the thermal conductivity, Cr can be set to 4.0% or less or 3.5% or less.
  • Mo and W are elements that dissolve in the substrate to increase hardness, and also elements that increase hardness by forming carbides, which contribute to secondary hardening during tempering. It is an element. It is also an element that improves hardenability. Since W has an atomic weight about twice that of Mo, it can be specified by (Mo + 1 / 2W) (of course, only one of them may be added, or both may be added). However, if the content of Mo or W is too large, the amount of alloy in the mold steel will increase, and the thermal conductivity of the mold will decrease.
  • Mo and W are 1.2 to 3.5% in the relational expression of the Mo equivalent of (Mo + 1 / 2W). It is preferably 1.5% or more. More preferably, it is 1.7% or more. More preferably, it is 1.9% or more. Further, it is preferably 3.4% or less. More preferably, it is 3.2% or less. In the case of the present invention, since W is an expensive element, all of W can be replaced with Mo. At this time, Mo: 1.2 to 3.5% (the same applies to the preferable range). However, W may be contained as an impurity.
  • V is an element that increases hardness by forming carbides, and is an element that contributes to secondary curing during tempering.
  • V is 0.1 to 0. Limiting to 5.5% is important to achieve both high thermal conductivity and high hardness properties. It is preferably 0.2% or more. Further, it is preferably 0.45% or less, and more preferably 0.4% or less.
  • Ni is an element that contributes to improving the toughness of the mold. Further, in the present embodiment, the strength characteristics of the mold steel can be improved by combining with Al to form and precipitate a Ni—Al intermetallic compound and secondary curing. However, if the amount of Ni is too large, the thermal conductivity may be significantly lowered due to the increase in the alloy amount of the mold steel, so the Ni is set to 0.15 to 0.6%. Preferably, it is 0.2% or more. Further, it is preferably 0.5% or less, and more preferably 0.45% or less.
  • Cu is an element that can improve the strength characteristics of mold steel by combining with Al to form and precipitate intermetallic compounds and secondary hardening.
  • Cu is set to 0.1 to 0.6%. It is preferably 0.2% or more. Further, it is preferably 0.5% or less, and more preferably 0.45% or less.
  • Al combines with Ni and Cu to form an intermetallic compound. If the Al content is too low, the intermetallic compound is not sufficiently formed and the strength improving effect cannot be obtained. On the other hand, if the Al content is too high, the thermal conductivity of the mold may be significantly reduced. There is. Therefore, Al is set to 0.1 to 0.6%. It is preferably 0.2% or more. Also. It is preferably 0.5% or less, and more preferably 0.4% or less.
  • Ni / Al is preferably 1.0 to 2.0 in order to form and precipitate the intermetallic compound in just proportion.
  • the more preferable upper limit of Ni / Al is 1.7, and the more preferable upper limit is 1.5.
  • it is preferable that Cu / Al is 1.0 to 2.0 in order to form and precipitate the intermetallic compound without excess or deficiency.
  • the more preferable upper limit of Cu / Al is 1.7, and the more preferable upper limit is 1.5.
  • the thermal conductivity of the mold decreases as the amount of alloy in the mold steel increases, it is preferable that the balance other than the above elemental species is substantially Fe. ..
  • elemental species not specified here for example, elemental species such as P, S, Ca, Mg, O (oxygen), N (nitrogen)
  • P is preferably regulated to 0.05% or less.
  • S is preferably regulated to 0.03% or less. If the amount of S is too large, the hot workability deteriorates when the steel ingot is agglomerated. Therefore, S is preferably regulated to 0.01% or less. More preferably, it is regulated to 0.008% or less.
  • the hardness of the hot working die of the present invention is a value measured at room temperature (normal temperature), and can achieve a sufficient hardness such as 52 HRC or more, which imparts excellent wear resistance to the die. be able to. Then, by adjusting the tempering temperature, the hardness of the mold can be preferably 53 HRC or more. In the present invention, it is not necessary to specify the upper limit of the hardness of the mold.
  • the mold of the present embodiment has a thermal conductivity of 25 W / (m ⁇ K) when the hardness of the mold is adjusted to 52 HRC by quenching and tempering the mold steel having the above-mentioned composition. That is all.
  • This thermal conductivity is a value measured at room temperature (normal temperature). It is preferably 28 W / (m ⁇ K) or more.
  • the mold of the present invention having the above-mentioned thermal conductivity can further increase the thermal conductivity by making the hardness less than 52 HRC when it is desired to increase the thermal conductivity. It is also possible to adjust the hardness of the mold to more than 52 HRC while having sufficient thermal conductivity.
  • the thermal conductivity is preferably 30 W / (m ⁇ K) or more, and 32 W / (m ⁇ K) or more. More preferably, it is 34 W / (m ⁇ K) or more.
  • the thermal conductivity is preferably 25 W / (m ⁇ K) or more, and more preferably 27 W / (m ⁇ K) or more.
  • Such a mold can be achieved by a mold steel having a heat treatment property showing a hardness of 52 HRC or more when tempered at 575 ° C.
  • the quenching temperature before tempering can be, for example, 1030 ° C.
  • the mold steel of the present invention has the above heat treatment characteristics. As a result, high hardness can be maintained and high thermal conductivity can be maintained in the mold used in, for example, the hot stamping method (for example, 100 to 400 ° C.).
  • the upper limit of the thermal conductivity of the mold it is not necessary to specify the upper limit of the thermal conductivity of the mold.
  • the hardness of the mold decreases as the tempering temperature is raised (for example, adjusted to a temperature exceeding 600 ° C.)
  • it is about 50 W / (m ⁇ K). Is realistic. It is preferably 47 W / (m ⁇ K) or less. More preferably, it is 45 W / (m ⁇ K) or less.
  • the upper limit of the thermal conductivity is about 40 W / (m ⁇ K). It is preferably 38 W / (m ⁇ K) or less.
  • the hot working die of the present invention preferably has a nitride layer on its working surface.
  • the hot working die of the present invention has both high hardness and high thermal conductivity. Then, when the working surface of the mold further has a nitrided layer, the wear resistance (hardness of the working surface) of the mold can be further improved. Further, due to the quenching and tempering characteristics of the mold steel of the present invention, it is possible to suppress a decrease in hardness of the mold body during the nitriding treatment.
  • the working surface is the surface of the mold that comes into contact with the work material being hot-worked.
  • the method for producing a hot working die of the present invention is to quench and temper the above-mentioned die steel.
  • the quenching temperature varies depending on the target hardness and the like, but can be, for example, approximately 1020 to 1080 ° C. It is preferably 1050 ° C. or lower.
  • the mold steel hardened at this quenching temperature is tempered at a tempering temperature of, for example, 540 to 620 ° C., thereby stably achieving a hardness of 52 HRC or more and a thermal conductivity of 25 W.
  • a mold of / (m ⁇ K) or more can be obtained.
  • the upper limit of the tempering temperature is preferably about 600 ° C. More preferably, it is 595 ° C. or lower. More preferably, it is 590 ° C. or lower.
  • the lower limit of the tempering temperature is preferably about 550 ° C. More preferably, it is 555 ° C. or higher. More preferably, it is 560 ° C. or higher.
  • the mold steel of the present invention that satisfies the heat treatment characteristics criteria is 540 to Hardness of 45 HRC or higher can be maintained even in a wide tempering temperature range of 620 ° C.
  • the peak hardness is higher than 52 HRC, for example, 53 HRC or higher, 54 HRC or higher, 55 HRC or higher, the hardness of 52 HRC or higher can be maintained in a wide tempering temperature range.
  • a thermal conductivity of 25 W / (m ⁇ K) or more can be obtained in this wide tempering temperature range, and the thermal conductivity can be improved particularly at a tempering temperature of 575 ° C. or higher.
  • the mold steel of the present invention is prepared into a hot working mold having a predetermined hardness by quenching and tempering. During this period, the mold steel is adjusted to the shape of the hot working mold by various machining such as cutting and drilling. The timing of this machining can be performed in a state where the hardness before quenching and tempering is low (that is, in an annealed state). Then, in this case, finishing processing may be performed after quenching and tempering. In some cases, the above machining may be performed in the pre-hardened state after quenching and tempering in combination with the above finishing process.
  • the working surface of the die after the above quenching and tempering is further subjected to nitriding treatment.
  • nitriding treatment for example, gold having a thermal conductivity of 25 W / (m ⁇ K) when the hardness is adjusted to 52 HRC. You can get the mold. Since the mold steel having the above-mentioned composition is also excellent in nitriding characteristics, the working surface of the mold after this quenching and tempering is further subjected to nitriding treatment to form the mold. Abrasion resistance (hardness of work surface) can be improved.
  • nitriding treatments such as gas nitriding treatment and salt bath nitriding treatment can be applied to the conditions of the nitriding treatment.
  • a 10 kg steel ingot having the component composition shown in Table 1 was melted. Then, the ingot was heated to 1160 ° C., forged by a hammer, and then allowed to cool, and the steel material after the cooling was allowed to be annealed at 870 ° C. to obtain No. 1 of the present invention. Steels 1 to 6 and No. 1 which is a comparative example. 7-9 steels were made.
  • No. which is an example of the present invention. 1 to 7 achieved a tempering hardness of 52 HRC or more within the range of the tempering temperature of 550 to 600 ° C. On the other hand, No. In each of 7 to 9, the tempering hardness was lower than 52HRC in the tempering temperature range of 500 to 650 ° C.
  • No. 1 which is an example of the present invention. It was confirmed that 1 to 6 achieved a thermal conductivity of 25 W / (m ⁇ K) or more.
  • No. The thermal conductivity of 7 to 9 is the same as that of the present invention, but the peak hardness does not reach 52 HRC in the first place. For this reason, in the case of mold steel as in the comparative example, the hardness is further reduced when the thermal conductivity is to be adjusted (specifically, when the tempering temperature is increased in order to increase the thermal conductivity). Therefore, it is not possible to handle molds with various required characteristics.
  • the mold steel of the present invention example has excellent temper softening resistance in addition to sufficient peak hardness. Therefore, the mold steel of the present invention example has higher thermal conductivity and high hardness characteristics. It was confirmed that it has advantageous characteristics for use in die processing.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Heat Treatment Of Articles (AREA)
  • Mounting, Exchange, And Manufacturing Of Dies (AREA)

Abstract

L'invention concerne : un acier qui est destiné à une matrice et qui permet la production d'une matrice destinée à un formage à chaud et ayant à la fois une dureté élevée et une conductivité thermique élevée; une matrice pour formage à chaud; et un procédé de fabrication de celle-ci.　L'acier pour une matrice de formage à chaud présente une composition contenant, en % en masse, de 0,45 à 0,65 % de C, de 0,1 à 0,6 % de Si, de 0,1 à 2,5 % de Mn, de 1,0 à 6,0 % de Cr, de 1,2 à 3,5 % de (Mo +1/2W), Mo et W étant contenus indépendamment ou en association, de 0,1 à 0,5 % de V, de 0,15 à 0,6 % de Ni, de 0,1 à 0,6 % de Cu et de 0,1 à 0,6 % d'Al, le reste étant du Fe et des impuretés inévitables. En outre, cette matrice pour formage à chaud a ladite composition, et ce procédé de fabrication est destiné à la fabrication de ladite matrice pour un formage à chaud.
PCT/JP2021/010616 2020-03-16 2021-03-16 Acier pour matrice de formage à chaud, matrice pour formage à chaud et son procédé de fabrication WO2021187484A1 (fr)

Priority Applications (4)

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EP21772321.2A EP4123047A1 (fr) 2020-03-16 2021-03-16 Acier pour matrice de formage à chaud, matrice pour formage à chaud et son procédé de fabrication
US17/911,411 US20230099300A1 (en) 2020-03-16 2021-03-16 Steel for hot working die, die for hot working, and manufacturing method for same
KR1020227031729A KR20220143067A (ko) 2020-03-16 2021-03-16 열간 가공용 금형용 강, 열간 가공용 금형 및 그 제조 방법
CN202180020353.6A CN115279932B (zh) 2020-03-16 2021-03-16 热加工用模具用钢、热加工用模具及其制造方法

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JP2020045361A JP2021147624A (ja) 2020-03-16 2020-03-16 熱間加工用金型用鋼、熱間加工用金型およびその製造方法

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JP5744300B1 (ja) 2014-11-11 2015-07-08 日本高周波鋼業株式会社 熱間工具鋼
JP2017043814A (ja) 2015-08-28 2017-03-02 大同特殊鋼株式会社 金型用鋼および金型
JP2017053023A (ja) 2015-09-11 2017-03-16 大同特殊鋼株式会社 金型用鋼及び成形具
JP2018024931A (ja) 2015-09-02 2018-02-15 大同特殊鋼株式会社 金型用鋼及び成形具
JP2020026567A (ja) * 2018-08-17 2020-02-20 日立金属株式会社 ホットスタンプ用金型用鋼、ホットスタンプ用金型およびその製造方法
JP2021011618A (ja) * 2019-07-08 2021-02-04 山陽特殊製鋼株式会社 熱伝導率に優れる熱間工具鋼

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Publication number Priority date Publication date Assignee Title
JP2009120886A (ja) * 2007-11-13 2009-06-04 Kobe Steel Ltd 冷間金型用鋼および金型
JP2009242319A (ja) * 2008-03-31 2009-10-22 Daikin Ind Ltd 多官能含フッ素化合物及び該化合物の製造方法
JP5744300B1 (ja) 2014-11-11 2015-07-08 日本高周波鋼業株式会社 熱間工具鋼
JP2017043814A (ja) 2015-08-28 2017-03-02 大同特殊鋼株式会社 金型用鋼および金型
JP2018024931A (ja) 2015-09-02 2018-02-15 大同特殊鋼株式会社 金型用鋼及び成形具
JP2017053023A (ja) 2015-09-11 2017-03-16 大同特殊鋼株式会社 金型用鋼及び成形具
JP2020026567A (ja) * 2018-08-17 2020-02-20 日立金属株式会社 ホットスタンプ用金型用鋼、ホットスタンプ用金型およびその製造方法
JP2021011618A (ja) * 2019-07-08 2021-02-04 山陽特殊製鋼株式会社 熱伝導率に優れる熱間工具鋼

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CN115279932B (zh) 2023-12-29
CN115279932A (zh) 2022-11-01
US20230099300A1 (en) 2023-03-30
JP2021147624A (ja) 2021-09-27
EP4123047A1 (fr) 2023-01-25

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