JP7544488B2 - Hot work tool steel with excellent manufacturability and thermal conductivity - Google Patents
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- 229910001315 Tool steel Inorganic materials 0.000 title claims description 18
- 229910000831 Steel Inorganic materials 0.000 claims description 60
- 239000010959 steel Substances 0.000 claims description 60
- 150000001247 metal acetylides Chemical class 0.000 claims description 16
- 229910000734 martensite Inorganic materials 0.000 claims description 15
- 229910001563 bainite Inorganic materials 0.000 claims description 14
- 229910052750 molybdenum Inorganic materials 0.000 claims description 9
- 229910052721 tungsten Inorganic materials 0.000 claims description 8
- 229910052796 boron Inorganic materials 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 229910052710 silicon Inorganic materials 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 238000005496 tempering Methods 0.000 description 31
- 238000010791 quenching Methods 0.000 description 27
- 230000000171 quenching effect Effects 0.000 description 27
- 230000000052 comparative effect Effects 0.000 description 24
- 238000012360 testing method Methods 0.000 description 15
- 239000011159 matrix material Substances 0.000 description 11
- 230000007423 decrease Effects 0.000 description 9
- 238000004512 die casting Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 238000001816 cooling Methods 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000005242 forging Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000010191 image analysis Methods 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- -1 M23C6 Chemical class 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000011295 pitch Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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Description
本発明は、金型用鋼に関して、特にダイカストやホットスタンピングなどの、高温環境下で使用される金型用鋼に関する。 The present invention relates to mold steel, and in particular to mold steel used in high-temperature environments such as die casting and hot stamping.
近年、ダイカスト分野において、自動車の軽量化を目的としたアルミ部品の高強度化や、生産性向上を目的とした部品成形加工ピッチの短縮化から、ダイカスト金型への機械的及び熱的負荷が増大している。その結果、金型には摩耗・大割れなどの問題が生じやすくなっている。これらの問題に対応するため、金型材料には、硬度・靭性に優れる材料が求められている。 In recent years, in the field of die casting, the mechanical and thermal load on die casting dies has increased due to the strengthening of aluminum parts to reduce the weight of automobiles and the shortening of part forming processing pitches to improve productivity. As a result, dies are more susceptible to problems such as wear and large cracks. To address these issues, there is a demand for die materials with excellent hardness and toughness.
また、ホットスタンピングでは、被加工材である鋼板表面に発生したスケールによる金型の摩耗が問題となっており、金型材料には、高い硬度及び軟化抵抗性が求められている。 In addition, in hot stamping, wear of the die caused by scale that forms on the surface of the steel plate, which is the workpiece, is an issue, so the die material must have high hardness and resistance to softening.
さらに、ダイカスト・ホットスタンピング用金型は内部に冷却回路が作製されており、ここを流れる冷却水による冷却効率が生産サイクルスピードに大きく影響する。冷却効率を高める方法としては金型の高熱伝導率化がある。そのため、前述した生産性向上を目的とした、生産サイクルスピードの向上に対する要求に応えるためには、材料の特性として高い熱伝導率が必要である。 Furthermore, die casting and hot stamping dies have cooling circuits built in, and the cooling efficiency of the cooling water flowing through these circuits has a significant impact on the production cycle speed. One way to increase cooling efficiency is to increase the thermal conductivity of the die. Therefore, in order to meet the demand for faster production cycle speeds with the aim of improving productivity as mentioned above, a material with high thermal conductivity is required as a property.
また、上記の金型を実際に製造することを検討すると製造性、すなわち高い熱間加工性も必要である。 In addition, when considering actually manufacturing the above mold, manufacturability, i.e. high hot workability, is also necessary.
従来より、出願人はＣｕ及びＢを含まない熱伝導率に優れた熱間工具鋼を提案している（特許文献１参照。）。もっとも、この提案では、Ｃｕ及びＢが添加されておらず、また不完全焼入れ相であるベイナイトが形成され、靭性が不足するおそれがあった。さらに熱間加工性に関する記載も見当たらない。 The applicant has previously proposed a hot work tool steel that does not contain Cu or B and has excellent thermal conductivity (see Patent Document 1). However, this proposal does not contain Cu or B, and bainite, an incompletely hardened phase, is formed, which may result in insufficient toughness. Furthermore, there is no description of hot workability.
また、Ｍｎ量が多い金型用鋼が提案されている（特許文献２参照。）。しかし、Ｍｎが１．５％より多いので、Ｍｎの過剰添加によって熱伝導率が低下しやすい。また、熱間加工性に関する記載も見当たらない。 In addition, mold steels with a high Mn content have been proposed (see Patent Document 2). However, since the Mn content is more than 1.5%, the thermal conductivity is likely to decrease due to the excessive addition of Mn. In addition, there is no description of hot workability.
また、Ｖ量の多い金型用鋼が提案されている（特許文献３参照。）。しかし、Ｖが０．５５％よりも多く、Ｖの過剰添加によって熱伝導率が低下しやすい。また、熱間加工性に関する記載も見当たらない。 In addition, mold steels with a high V content have been proposed (see Patent Document 3). However, the V content is greater than 0.55%, and excessive V addition tends to reduce thermal conductivity. In addition, there is no description of hot workability.
また、Ｃｒ量の多い金型用鋼が提案されている（特許文献４参照。）。しかし、Ｃｒが４．０％より多いので、Ｃｒの過剰添加によって熱伝導率が低下しやすい。また、熱間加工性に関する記載も見当たらない。 In addition, mold steels with a high Cr content have been proposed (see Patent Document 4). However, since the Cr content is more than 4.0%, the thermal conductivity is likely to decrease due to the excessive addition of Cr. In addition, there is no description of hot workability.
また、ダイカスト金型用プリハードン鋼が提案されている（特許文献５参照。）。しかし、Ｃ量が０．３５％以下と少なく、焼入焼戻し硬さが不足しやすい。また、熱間加工性に関する記載も見当たらない。 Prehardened steel for die-casting dies has also been proposed (see Patent Document 5). However, the C content is low at 0.35% or less, and the quench-tempered hardness is likely to be insufficient. There is also no description of hot workability.
また、Ｍｏ＋１／２Ｗの値の大きい熱間工具鋼が提案されている（特許文献６参照。）。しかし、Ｍｏ＋１／２Ｗの値が３．０より大きく、ＭｏまたはＷの過剰添加によって熱伝導率が低下しやすい。また、熱間加工性に関する記載も見当たらない。 In addition, hot work tool steels with a large Mo+1/2W value have been proposed (see Patent Document 6). However, the Mo+1/2W value is greater than 3.0, and the thermal conductivity is likely to decrease due to the excessive addition of Mo or W. In addition, there is no description of hot workability.
また、Ｎｉが多い熱間工具鋼が提案されている（特許文献７参照。）。しかし、Ｎｉが３．０％以上と多く、Ｎｉの過剰添加によって熱伝導率が低下しやすい。また、熱間加工性に関する記載は見当たらない。 Hot work tool steel with a high Ni content has also been proposed (see Patent Document 7). However, the Ni content is high at 3.0% or more, and excessive Ni addition tends to reduce thermal conductivity. In addition, there is no description of hot workability.
その他にも金型用鋼が提案されている（特許文献８参照。）。もっとも、この提案はＢもしくはＣｕを含まず、靱性に不足しやすい。熱間加工性に関する記載もみあたらない。 Other die steels have also been proposed (see Patent Document 8). However, these proposals do not contain B or Cu and tend to lack toughness. There is no description of hot workability.
本発明の目的は、高い熱間加工性、熱伝導率、硬度、軟化抵抗性、靭性を兼ね備えており、ダイカストやホットスタンピングなどの金型用鋼に適用可能な熱間工具鋼を提供することである。 The object of the present invention is to provide a hot work tool steel that combines high hot workability, thermal conductivity, hardness, softening resistance, and toughness, and can be used as a die steel for die casting, hot stamping, etc.
本願発明者らは鋭意開発を進めた結果、鋼の合金成分、熱間加工性の指標となるパラメータ、鋼の組織、炭化物の状態をそれぞれ規定することで、高い熱間加工性、熱伝導率、硬度、軟化抵抗性、靭性を兼備した熱間工具鋼が得られることを見出した。 As a result of the intensive development of the present inventors, it has been discovered that by specifying the alloy composition of the steel, the parameters that indicate hot workability, the structure of the steel, and the state of the carbides, it is possible to obtain a hot work tool steel that combines high hot workability, thermal conductivity, hardness, softening resistance, and toughness.
すなわち、本発明の課題を解決する第１の手段は、 質量％で、Ｃ：０．３５％超～０．７０％、Ｓｉ：０．０１％～１．２０％、Ｍｎ：０．０１％～１．５０％、Ｃｒ：０．３５％～４．００％、Ｃｕ：０．１０％～２．５０％、Ｎｉ：０．１０％～２．９９％、Ｖ：０．１０％超～０．５５％、Ｂ：０．０００１％～０．０１００％、Ｏ：０．００５０％以下であって、ＭｏとＷのいずれか１種または双方を含有し、かつ、Ｍｏ：３．００％以下、Ｗ：６．００％以下、Ｍｏ＋１／２Ｗ：０．５０％～３．００％であって、残部がＦｅ及び不可避不純物からなる鋼であり、
Ｂ＋Ｏ＋Ｎ：０．０４２０％以下を充たし、さらに、次の式に示すＫの値が１５．６以上であること、を特徴とする熱間工具鋼である。
式：Ｋ＝３６．０４－１２．６５Ｃ－１．５８Ｍｏ－０．７９Ｗ－９．３４Ｍｎ－１９．０１Ａｌ＋０．６９Ｎｉ－０．３４Ｃｕ
（ただし、この式の右辺の各元素記号には、鋼を構成する元素成分の百分率の数値を代入する。）
That is, a first means for solving the problems of the present invention is a steel containing, in mass %, C: more than 0.35% to 0.70%, Si: 0.01% to 1.20%, Mn: 0.01% to 1.50%, Cr: 0.35% to 4.00%, Cu: 0.10% to 2.50%, Ni: 0.10% to 2.99%, V: more than 0.10% to 0.55%, B: 0.0001% to 0.0100%, O: 0.0050% or less, one or both of Mo and W, and Mo: 3.00% or less, W: 6.00% or less, Mo+1/2W: 0.50% to 3.00%, with the balance being Fe and unavoidable impurities;
This hot work tool steel is characterized in that B+O+N is 0.0420% or less, and further, the value of K shown in the following formula is 15.6 or more.
Formula: K=36.04-12.65C-1.58Mo-0.79W-9.34Mn-19.01Al+0.69Ni-0.34Cu
(However, the percentage of each element that makes up the steel is substituted for each element symbol on the right side of this formula.)
その第２の手段は、第１の手段に記載の鋼の成分に、さらにＮ：０．０００１％～０．０４００％が添加されていることを特徴とするものである。 The second method is characterized in that N: 0.0001% to 0.0400% is further added to the steel components described in the first method.
その第３の手段は、第１または第２の手段の記載の鋼の成分に、さらにＴｉ：０．００１％～０．１５０％が添加されていることを特徴とするものである。 The third means is characterized in that Ti: 0.001% to 0.150% is further added to the components of the steel described in the first or second means.
その第４の手段は、第１～第３のいずれか１の手段の記載の鋼の成分に、さらにＡｌ：０．００１％以上０．２００％以下が添加されていることを特徴とするものである。 The fourth means is characterized in that Al: 0.001% or more and 0.200% or less is further added to the composition of the steel described in any one of the first to third means.
その第５の手段は、焼入焼戻しされた状態であって、その組織が、マルテンサイト単相組織であること、またはマルテンサイトの割合が８０％以上のマルテンサイトとベイナイトの混合組織であること、を特徴とする、第１～第４のいずれか１の手段に記載の熱間工具鋼である。 The fifth means is a hot work tool steel according to any one of the first to fourth means, characterized in that in a quenched and tempered state, the structure is a martensite single phase structure, or a mixed structure of martensite and bainite with a martensite ratio of 80% or more.
その第６の手段は、焼入焼戻しされた状態であって、Ｍ23Ｃ６、Ｍ6Ｃ、Ｍ7Ｃ3、Ｍ3Ｃ、Ｍ2Ｃ、ＭＣの全炭化物中に占めるＭ23Ｃ6とＭ6Ｃ炭化物の割合が９０％以下であること、を特徴とする、第１～第５のいずれか１の手段に記載の熱間工具鋼である。 The sixth aspect of the present invention is a hot work tool steel according to any one of the first to fifth aspects, characterized in that in a quenched and tempered state, the ratio of M23C6 and M6C carbides to all carbides of M23C6 , M6C , M7C3 , M3C , M2C and MC is 90% or less.
本発明における高熱間加工性とは、鋼塊状態にてグリーブル試験を１１００℃で実施したときの絞りが７０％以上のことをいう。
また、本発明における高熱伝導率とは、焼入焼戻し後の室温での熱伝導率が２５．０Ｗ／ｍ・Ｋ以上のことをいう。
また、本発明における高硬度とは、焼入焼戻し後の室温での硬さが４８．０ＨＲＣ以上のことをいう。
また、本発明における高靱性とは、焼入焼戻し後の室温でのシャルピー衝撃値が２０Ｊ／ｃｍ2以上のことをいう。
また、本発明における高軟化抵抗性とは、焼入焼戻し後に６００℃で１００ｈ保持後の室温での硬さが３２．０ＨＲＣ以上のことをいう。
In the present invention, high hot workability refers to a reduction in area of 70% or more when a Gleeble test is carried out at 1100° C. in the state of a steel ingot.
In the present invention, high thermal conductivity means a thermal conductivity of 25.0 W/m·K or more at room temperature after quenching and tempering.
In the present invention, high hardness refers to a hardness of 48.0 HRC or more at room temperature after quenching and tempering.
Further, in the present invention, high toughness means a Charpy impact value of 20 J/cm 2 or more at room temperature after quenching and tempering.
In the present invention, high softening resistance means that the hardness at room temperature after quenching and tempering and then holding at 600° C. for 100 hours is 32.0 HRC or more.
本発明の手段によると、高熱間加工性、高熱伝導率、高硬度、高靱性、高軟化抵抗性をバランスよく兼ね備えた熱間工具鋼が得られる。すなわち、本発明の手段による熱間工具鋼は、鋼塊状態にてグリーブル試験を１１００℃で実施したときの絞りが７０％以上の高熱間加工性を示し、焼入焼戻し後の室温での熱伝導率が２５．０Ｗ／ｍ・Ｋ以上の高熱伝導率であって、焼入焼戻し後の室温での硬さが４８．０ＨＲＣ以上と高硬度であって、焼入焼戻し後の室温でのシャルピー衝撃値が２０Ｊ／ｃｍ2以上の高靱性であって、焼入焼戻し後に６００℃で１００ｈ保持後の室温での硬さが３２．０ＨＲＣ以上といった高軟化抵抗性を示すものとなり、これらの全ての特性を兼ね備えるものとなる。 According to the present invention, a hot work tool steel having a good balance of high hot workability, high thermal conductivity, high hardness, high toughness, and high softening resistance can be obtained. That is, the hot work tool steel according to the present invention exhibits high hot workability with a reduction of 70% or more when a Gleeble test is carried out at 1100°C in a steel ingot state, a high thermal conductivity of 25.0 W/m·K or more at room temperature after quenching and tempering, a high hardness of 48.0 HRC or more at room temperature after quenching and tempering, high toughness with a Charpy impact value of 20 J/ cm2 or more at room temperature after quenching and tempering, and a high softening resistance with a hardness of 32.0 HRC or more at room temperature after holding at 600°C for 100 hours after quenching and tempering, and thus exhibits all of these characteristics.
本発明の実施の形態を説明するに先立ち、本発明の鋼の各成分を規定する理由を以下に説明する。なお、以下の％は質量％である。 Before describing the embodiments of the present invention, the reasons for specifying each component of the steel of the present invention will be explained below. Note that the following percentages are mass percentages.
Ｃ：０．３５％超～０．７０％、
Ｃは固溶することでマトリックスを強化し、また、炭化物を形成することで析出強化を促す元素であることから、Ｃは０．３５％より多いものとする。０．３５％以下であると十分な焼入焼戻硬さが得られない。他方、Ｃが０．７０％より多いと偏析を助長し、靭性を低下させる。また、熱間加工性が悪化する。そこで、Ｃは、０．３５％超～０．７０％とする。好ましくは、Ｃは０．５５％超～０．７０％である。
C: more than 0.35% to 0.70%,
Since C is an element that strengthens the matrix by dissolving in solid solution and promotes precipitation strengthening by forming carbides, the C content is set to be more than 0.35%. Sufficient quenching and tempering hardness cannot be obtained. On the other hand, if the C content is more than 0.70%, segregation is promoted, and the toughness is reduced. In addition, hot workability is deteriorated. Therefore, the C content is set to 0. C is more than 0.35% to 0.70%. Preferably, C is more than 0.55% to 0.70%.
Ｓｉ：０．０１％～１．２０％、
Ｓｉは製鋼時の脱酸剤として必要な元素であり、少ないと十分に脱酸されない。また、Ｓｉはマトリックスに固溶することで硬さを向上させる効果がある。そこで、Ｓｉは０．０１％以上とする。他方、Ｓｉが１．２０％を超えると、炭化物を形成することなくマトリックスに固溶して熱伝導率を低下させることとなる。
そこで、Ｓｉは０．０１％～１．２０％とする。好ましくは、Ｓｉは０．０５％～１．００％である。
Si: 0.01% to 1.20%,
Silicon is an element necessary as a deoxidizer during steelmaking, and if there is too little, the deoxidization will not be sufficient. Silicon also has the effect of improving hardness by dissolving in the matrix. Therefore, the amount of silicon is set to 0.01 On the other hand, if the Si content exceeds 1.20%, it will dissolve in the matrix without forming carbides, resulting in a decrease in thermal conductivity.
Therefore, the Si content is set to 0.01% to 1.20%, and preferably, the Si content is set to 0.05% to 1.00%.
Ｍｎ：０．０１％～１．５０％、
Ｍｎは製鋼時の脱酸剤として必要な元素である。少ないと十分に脱酸されない。そこで、Ｍｎは０．０１％以上とする。他方、１．５０％を超えると、マトリックスに固溶して熱伝導率を低下させる。そこで、Ｍｎは０．０１％～１．５０％とする。好ましくは、Ｍｎは０．０５％～０．９２％未満である。より好ましくは、Ｍｎは０．１０％～０．５０％未満である。
Mn: 0.01% to 1.50%,
Mn is an element necessary as a deoxidizer during steelmaking. If there is too little, deoxidization is not sufficient. Therefore, the Mn content is set to 0.01% or more. On the other hand, if it exceeds 1.50%, it will dissolve in the matrix and Therefore, Mn is set to 0.01% to 1.50%. Preferably, Mn is set to 0.05% to less than 0.92%. More preferably, Mn is set to 0. It is between 10% and less than 0.50%.
Ｃｒ：０．３５％～４．００％、
Ｃｒは焼入性を向上させ、ベイナイト形成による靱性の低下を抑制するのに必要な元素である。十分な靭性が得られないので、Ｃｒは０．３５％以上とする。他方、多すぎると、マトリックスに固溶して熱伝導率を低下させる為。また、多すぎると高温で粗大化しやすいＭ23Ｃ6炭化物が焼戻し時に析出し、軟化抵抗性が低下するため、Ｃｒは４．００％以下とする。
そこで、Ｃｒは０．３５％～４．００％である。好ましくは、Ｃｒは０．４０％～２．６０％未満である。より好ましくは、Ｃｒは０．５０～２．１０％未満である。
Cr: 0.35% to 4.00%,
Cr is an element necessary for improving hardenability and suppressing the decrease in toughness due to the formation of bainite. Since sufficient toughness cannot be obtained, the Cr content is set to 0.35% or more. On the other hand, if the Cr content is too high, , to dissolve in the matrix and reduce thermal conductivity. Also, if there is too much, M23C6 carbide , which tends to coarsen at high temperatures, precipitates during tempering, reducing softening resistance, so Cr is set to 4.00%. The following applies.
Therefore, Cr is 0.35% to 4.00%. Preferably, Cr is 0.40% to less than 2.60%. More preferably, Cr is 0.50% to less than 2.10%. be.
Ｃｕ：０．１０％～２．５０％、
Ｃｕは焼入性を向上させ、ベイナイト形成による靱性の低下を抑制するのに必要な元素である。十分な靭性が得られないので、Ｃｕは０．１０％以上とする。他方、多すぎると、熱間加工性が悪化する。また、マトリックスに固溶して熱伝導率を低下させる。そこで、Ｃｕは２．５０％以下とする。
そこでＣｕは０．１０％～２．５０％である。好ましくは、Ｃｕは０．３０％～２．２０％である。
Cu: 0.10% to 2.50%,
Cu is an element necessary for improving hardenability and suppressing the decrease in toughness due to the formation of bainite. Since sufficient toughness cannot be obtained, the Cu content is set to 0.10% or more. On the other hand, if the Cu content is too high, In addition, Cu dissolves in the matrix and reduces the thermal conductivity. Therefore, the Cu content is set to 2.50% or less.
Therefore, Cu is 0.10% to 2.50%. Preferably, Cu is 0.30% to 2.20%.
Ｎｉ：０．１０％～２．９９％、
ＮｉはＣｒと同様に、焼入れ性を向上させ、ベイナイト形成による靱性の低下を抑制する元素である。また、Ｃｕによる赤熱脆化を防ぐことから、Ｎｉは０．１０％以上とする。他方、多すぎると、マトリックスに固溶して熱伝導率を低下させるので、２．９９％以下とする。
そこで、Ｎｉは０．１０％～２．９９％とする。好ましくは、Ｎｉは０．１０％～２．００％である。
Ni: 0.10% to 2.99%,
Ni, like Cr, is an element that improves hardenability and suppresses the decrease in toughness caused by the formation of bainite. In addition, in order to prevent red embrittlement caused by Cu, the Ni content is set to 0.10% or more. If the amount is too large, it dissolves in the matrix and reduces the thermal conductivity, so the amount is set to 2.99% or less.
Therefore, the Ni content is set to 0.10% to 2.99%, and preferably, the Ni content is set to 0.10% to 2.00%.
ＭｏとＷのいずれか１種または双方を含有するものであって、
Ｍｏ：３．００％以下、
Ｗ：６．００％以下、
Ｍｏ＋１／２Ｗ：０．５０％～３．００％、
Ｍｏ及びＷは、いずれも焼戻し時の二次硬化を促進し、焼入焼戻し硬さを高める元素である。少ないと十分な焼入焼戻硬さが得られない。これらの効果を得るためには、Ｍｏ＋１／２Ｗ：０．５０％である。
もっとも、多すぎると、マトリックスに残存するＭｏやＷが増加し、熱伝導率を低下させるので、Ｍｏと１／２Ｗの合計量で３．００％以下とする。
そこで、Ｍｏ＋１／２Ｗは、０．５０％～３．００％とする。好ましくは、Ｍｏ＋１／２Ｗは１．５０％～３．００％である。
Contains either one or both of Mo and W,
Mo: 3.00% or less,
W: 6.00% or less,
Mo+1/2W: 0.50% to 3.00%,
Both Mo and W are elements that promote secondary hardening during tempering and increase the hardness after quenching and tempering. If the content is too low, sufficient hardness after quenching and tempering cannot be obtained. To obtain these effects, Mo+1/2W: 0.50% is required.
However, if the amount is too large, the amount of Mo and W remaining in the matrix increases, lowering the thermal conductivity, so the total amount of Mo and 1/2 W is set to 3.00% or less.
Therefore, Mo+1/2W is set to 0.50% to 3.00%, and preferably, Mo+1/2W is set to 1.50% to 3.00%.
Ｖ：０．１０％超～０．５５％、
Ｖは、焼戻し時の二次硬化を促進し、焼入焼戻し硬さを高める。Ｖが少ないと十分な焼入焼戻し硬さが得られない。他方、Ｖが多すぎると、マトリックスに残存するＶが増加し、熱伝導率を低下させる。そこで、Ｖは０．１０％超～０．５５％とする。好ましくは、０．２５％～０．４５％未満である。
V: more than 0.10% to 0.55%,
V promotes secondary hardening during tempering and increases the hardness after quenching and tempering. If there is too little V, sufficient hardness after quenching and tempering cannot be obtained. On the other hand, if there is too much V, the V remaining in the matrix Therefore, the V content is set to more than 0.10% and less than 0.55%, and preferably to 0.25% and less than 0.45%.
Ｂ：０．０００１％～０．０１００％、
Ｂは微量添加により焼入性を向上させ、ベイナイト形成による靱性の低下を抑制するのに必要な元素である。Ｂが少なすぎると十分な靭性が得られないが、Ｂが多すぎると焼戻し時に粗大な炭化物を形成し、靭性が低下する。また、融点を下げ、熱間加工性が悪化する。そこで、Ｂは０．０００１％～０．０１００％とする。好ましくは、０．０００５％～０．００７５％である。
B: 0.0001% to 0.0100%,
B is an element that is necessary to improve hardenability by adding a small amount and to suppress the decrease in toughness due to the formation of bainite. If there is too little B, sufficient toughness cannot be obtained, but if there is too much B, the steel will become brittle during tempering. It forms coarse carbides and reduces toughness. It also lowers the melting point and deteriorates hot workability. Therefore, B is set to 0.0001% to 0.0100%, preferably 0.0005% to 0.0100%. It is 0.0075%.
Ｏ：０．００５０％以下、
Ｏは多すぎると熱間加工性が悪化する。また、Ｏの過剰添加は精錬の時間、コストの上昇を招く。そこで、Ｏは、０．００５０％以下とする。好ましくは、Ｏは０．００３０％以下である。
O: 0.0050% or less,
Too much O deteriorates hot workability. Moreover, excessive addition of O increases the refining time and costs. Therefore, O is set to 0.0050% or less. Preferably, O is set to 0. 0.030% or less.
Ｂ＋Ｏ＋Ｎ：０．０４２０％以下、
Ｂは過剰であると、融点を下げ、熱間加工性が悪化する。Ｏは多すぎると熱間加工性が悪化する。Ｎは多すぎると熱間加工性が悪化する。そこで、ＢとＯとＮの合計量が多すぎると、熱間加工性が悪化する。そこで、Ｂ＋Ｏ＋Ｎの合計量は質量％で０．０４２０％以下とする。好ましくは、０．０３００％以下とする。
B+O+N: 0.0420% or less,
If B is excessive, the melting point is lowered and hot workability is deteriorated. If O is too much, hot workability is deteriorated. If N is too much, hot workability is deteriorated. Therefore, B and O If the total amount of B and N is too large, the hot workability deteriorates. Therefore, the total amount of B+O+N is set to 0.0420% or less by mass%, and preferably to 0.0300% or less.
Ｋの値：１５．６以上、
Ｋの値は、熱間加工性の１つの指標であって、以下の式から求まる。
Ｋ＝３６．０４－１２．６５Ｃ－１．５８Ｍｏ－０．７９Ｗ－９．３４Ｍｎ－１９．０１Ａｌ＋０．６９Ｎｉ－０．３４Ｃｕ（ただし、式の右辺にある各元素記号には鋼を構成する元素成分の百分率の数値を代入する。）
Ｋの値は１５．６未満であると、熱間加工性が悪化する。そこで、Ｋの値は、１５．６以上とする。好ましくはＫの値は１９．４以上である。
K value: 15.6 or more,
The value of K is an index of hot workability and is calculated by the following formula.
K = 36.04 - 12.65C - 1.58Mo - 0.79W - 9.34Mn - 19.01Al + 0.69Ni - 0.34Cu (where the numerical percentage of the elemental components constituting the steel is substituted for each element symbol on the right side of the formula.)
If the value of K is less than 15.6, the hot workability deteriorates. Therefore, the value of K is set to 15.6 or more, and preferably, the value of K is 19.4 or more.
さらに、以下のＮ、Ｔｉ、Ａｌは本発明の熱間工具鋼に以下に規定する範囲であれば適宜添加することのできる成分である。 Furthermore, the following N, Ti, and Al are components that can be added to the hot work tool steel of the present invention as appropriate within the ranges specified below.
Ｎ：０．０００１％～０．０４００％、
Ｎは、必ずしも添加する必要はないが、ＮはＣと同様に、焼入焼戻硬さを大きくするのに有効な元素であるから、必要に応じて添加することができる。他方、多すぎると熱間加工性が悪化する。また、過剰添加は精錬の時間、コストの上昇を招く。
そこで、Ｎは０．０００１％～０．０４００％とする。好ましくは、Ｎは０．０００１％～０．０３００％以下である。より好ましくは、Ｎは０．０００１％～０．０２００％以下である。
N: 0.0001% to 0.0400%,
It is not always necessary to add N, but since N, like C, is an effective element for increasing the hardness after quenching and tempering, it can be added as necessary. Moreover, excessive addition of Nb increases the refining time and costs.
Therefore, N is set to 0.0001% to 0.0400%. Preferably, N is set to 0.0001% to 0.0300% or less. More preferably, N is set to 0.0001% to 0.0200% or less. It is.
Ｔｉ：０．００１％～０．１５０％、
Ｔｉは必ずしも添加する必要はないが、ＴｉはＢによる焼入性向上を促進する効果がある。Ｔｉが添加されると、焼入れの際にＮがＴｉと化合物化することによって、固溶Ｂ量が増加し、焼入性は向上する。他方、Ｔｉの過剰添加は粗大なＴｉＮを形成し、靭性が低下する。
そこで、Ｔｉは０．００１％～０．１５０％とする。好ましくは、Ｔｉは０．００１％～０．１００％である。
Ti: 0.001% to 0.150%,
It is not always necessary to add Ti, but Ti has the effect of promoting the improvement of hardenability by B. When Ti is added, N forms a compound with Ti during hardening, and the amount of dissolved B is increased. On the other hand, excessive addition of Ti forms coarse TiN, which reduces toughness.
Therefore, the Ti content is set to 0.001% to 0.150%, and preferably, the Ti content is set to 0.001% to 0.100%.
Ａｌ：０．００１％以上０．２００％以下、
Ａｌは必ずしも添加する必要はないが、Ａｌはマトリクスに固溶して硬さを向上する元素であることから、必要に応じて添加することができる。他方、Ａｌは多すぎると熱間加工性が悪化する。また、マトリックスに固溶して熱伝導率を低下させる。
そこで、Ａｌは０．００１％～０．２００％とする。好ましくはＡｌは０．００５％～０．１５０％である。
Al: 0.001% or more and 0.200% or less,
Although it is not always necessary to add Al, since Al is an element that dissolves in the matrix to improve hardness, it can be added as necessary. On the other hand, if there is too much Al, it may deteriorate hot workability. In addition, it dissolves in the matrix and reduces thermal conductivity.
Therefore, the Al content is set to 0.001% to 0.200%, and preferably to 0.005% to 0.150%.
焼入焼戻し状態での組織：マルテンサイト単相組織であること、またはマルテンサイトの割合が８０％以上のマルテンサイトとベイナイトの混合組織であること、
不完全焼入れ相であるベイナイトが多く存在すると靭性が大幅に低下し、ホットスタンピング・ダイカスト金型として使われた際に、十分な金型寿命が得られなくなる。そこで、焼入焼戻し後の組織は、マルテンサイト単相か、あるいはベイナイトとマルテンサイトとの混合組織の場合にはマルテンサイトの割合を８０％以上とすることが好ましい。すなわち、ベイナイト組織は２０％未満であることが好ましい。
Structure in quenched and tempered state: A martensite single phase structure, or a mixed structure of martensite and bainite with a martensite ratio of 80% or more.
If a large amount of bainite, which is an incompletely hardened phase, is present, the toughness is significantly reduced, and when used as a hot stamping die casting die, a sufficient die life cannot be obtained. Therefore, the structure after quenching and tempering is preferably a martensite single phase, or in the case of a mixed structure of bainite and martensite, the proportion of martensite is preferably 80% or more. In other words, the bainite structure is preferably less than 20%.
焼入焼戻し状態でＭ23Ｃ６、Ｍ6Ｃ、Ｍ7Ｃ3、Ｍ3Ｃ、Ｍ2Ｃ、ＭＣの全炭化物中に占めるＭ23Ｃ6とＭ6Ｃ炭化物の割合：９０％以下
高温で粗大化しやすい炭化物のＭ23Ｃ6とＭ6Ｃが焼入焼戻し状態で多く存在すると、鋼材の軟化抵抗性が低下する。
そこで、Ｍ23Ｃ６、Ｍ6Ｃ、Ｍ7Ｃ3、Ｍ3Ｃ、Ｍ2Ｃ、ＭＣといった全炭化物中に占めるＭ23Ｃ6とＭ6Ｃ炭化物の割合を９０％以下とすることが好ましい。
Proportion of M23C6 and M6C carbides among all carbides of M23C6 , M6C , M7C3 , M3C , M2C and MC in the quenched and tempered state: 90% or less If there are a large number of M23C6 and M6C carbides , which are prone to coarsening at high temperatures, in the quenched and tempered state, the softening resistance of the steel material decreases.
Therefore, it is preferable that the ratio of M23C6 and M6C carbides to all carbides such as M23C6 , M6C , M7C3 , M3C , M2C and MC is 90% or less.
以下に本発明の発明鋼を用いた実施例とその特性の評価について記載する。本発明の熱間工具鋼は、以下の実験に記載のような成分と熱処理によって得ることができる。
まず、表１の発明鋼Ｎｏ．１～４４および表２の比較鋼Ｎｏ．４５～６７に記載の化学成分の鋼をそれぞれ１００ｋｇ真空誘導溶解炉にて溶製し、得られた鋼塊を幅６５ｍｍ、高さ３０ｍｍのブロックに熱間鍛伸した。
この一部より直径８ｍｍ、長さ１００ｍｍの試験片を作製し、熱間加工性の調査を実施した。
次に、残りの鍛伸材を８７０℃で焼なまし後、表面と中心の中間位置から直径２０ｍｍ、長さ１６０ｍｍの丸棒を採取した。この丸棒を１０３０℃に保持した後、空冷によって焼入れを行ない、５７０～６７０℃で２回焼戻しを行った後、これら試料について、組織観察、析出炭化物種の同定、熱伝導率、焼入焼戻し硬さ、靭性、軟化抵抗性の調査を実施した。
Examples of the present invention using the steel of the present invention and evaluation of its properties are described below. The hot work tool steel of the present invention can be obtained by the components and heat treatment described in the following experiments.
First, 100 kg of steels having chemical compositions shown in the invention steels No. 1 to 44 in Table 1 and the comparative steels No. 45 to 67 in Table 2 were melted in a vacuum induction melting furnace, and the resulting steel ingots were hot forged into blocks having a width of 65 mm and a height of 30 mm.
A test piece having a diameter of 8 mm and a length of 100 mm was prepared from a part of this material, and its hot workability was examined.
Next, the remaining forged and stretched material was annealed at 870°C, and then round bars with a diameter of 20 mm and a length of 160 mm were taken from the midpoint between the surface and the center. These round bars were held at 1030°C, quenched by air cooling, and tempered twice at 570-670°C. After that, the samples were subjected to structural observation, identification of precipitated carbide species, and investigation of thermal conductivity, quenching and tempering hardness, toughness, and softening resistance.
（組織観察について）
組織観察は、焼入焼戻し後の試料の鍛伸方向に平行な面を鏡面になるまで研磨し、ナイタールで腐食した後、走査型電子顕微鏡を用いて行った。総面積５００００μｍ2の領域において、組織観察をする際には、ベイナイトの有無を確認し、ベイナイトが確認された場合には、画像解析を用いてベイナイトの面積率の算出を百分率で行った。
(Regarding tissue observation)
The microstructure observation was performed using a scanning electron microscope after polishing the surface of the quenched and tempered sample parallel to the forging direction until it became a mirror surface and etching with nital. When observing the microstructure in an area of 50,000 μm2 in total, the presence or absence of bainite was confirmed, and when bainite was confirmed, the area ratio of bainite was calculated as a percentage using image analysis.
（炭化物観察について）
炭化物観察用の試験片は、焼入焼戻し後について試料の鍛伸方向に平行な面を研磨し、抽出レプリカ法により作成した。この試験片を、透過型電子顕微鏡の明視野像を用いて、総面積５００μｍ2の領域において観察した。
炭化物種は、電子線回折の結果と炭化物の形状から判断した。撮影した写真を画像解析し、全炭化物中に占めるＭ23Ｃ6、Ｍ6Ｃ炭化物の合計面積率を百分率で算出した。
なお、ここにいう全炭化物とは、Ｍ23Ｃ６、Ｍ6Ｃ、Ｍ7Ｃ3、Ｍ3Ｃ、Ｍ2Ｃ、ＭＣのことである。
(Carbide observation)
The test pieces for carbide observation were prepared by polishing the surface parallel to the forging direction of the samples after quenching and tempering, and using the extraction replica method. The test pieces were observed in a total area of 500 μm2 using a bright field image of a transmission electron microscope.
The type of carbide was determined from the results of electron beam diffraction and the shape of the carbide. The photographs were subjected to image analysis, and the total area ratio of M23C6 and M6C carbides to the total carbides was calculated as a percentage.
The total carbides referred to here include M23C6 , M6C , M7C3 , M3C , M2C , and MC.
（熱間加工性について）
熱間加工性は、グリーブル試験により評価を実施した。グリーブル試験には前記した直径８ｍｍＸ１００ｍｍの試験片を用い、７００℃～１３００℃でグリーブル試験を実施した。結果を表３、表４に熱間加工性（％）として示す。鋼塊状態にてグリーブル試験を１１００℃で実施したときの絞りが７０％以上のことを高熱間加工性であると評価した。
(Regarding hot workability)
The hot workability was evaluated by a Gleeble test. The above-mentioned test pieces having a diameter of 8 mm and a length of 100 mm were used in the Gleeble test, and the test was carried out at temperatures of 700°C to 1300°C. The results are shown in Tables 3 and 4 as hot workability (%). When the Gleeble test was carried out on a steel ingot at 1100°C, a reduction of 70% or more was evaluated as high hot workability.
（熱伝導率の測定）
熱伝導率の測定には、レーザフラッシュ法を用いた。焼入焼戻し後の試料を直径１０ｍｍ×１ｍｍの円柱形状に仕上げ加工し、試験に供した。熱伝導率は、室温で測定した。結果を表３、表４に熱伝導率（Ｗ／ｍ・Ｋ）として示す。焼入焼戻し後の室温での熱伝導率が２５．０Ｗ／ｍ・Ｋ以上のものを高熱伝導率であると評価した。
(Measurement of thermal conductivity)
The thermal conductivity was measured using a laser flash method. The samples after quenching and tempering were finished into a cylindrical shape of 10 mm diameter x 1 mm and subjected to testing. The thermal conductivity was measured at room temperature. The results are shown in Tables 3 and 4 as thermal conductivity (W/m·K). Samples with a thermal conductivity of 25.0 W/m·K or more at room temperature after quenching and tempering were evaluated as having high thermal conductivity.
（焼入焼戻し硬さ）
焼入焼戻し硬さはロックウェル硬さ試験機により室温で測定した。焼入焼戻状態の試料の鍛伸方向に垂直な面を硬さ測定した。結果を表３、表４に焼入焼戻し硬さ（ＨＲＣ）として示す。焼入焼戻し後の室温での硬さが４８．０ＨＲＣ以上のことを高硬度であると評価した。
(Quenched and tempered hardness)
The quenched and tempered hardness was measured at room temperature using a Rockwell hardness tester. The hardness was measured on a surface perpendicular to the forging direction of the quenched and tempered sample. The results are shown as quenched and tempered hardness (HRC) in Tables 3 and 4. A hardness of 48.0 HRC or more at room temperature after quenching and tempering was evaluated as high hardness.
（靱性）
靱性は、室温でのシャルピー衝撃試験により評価を実施した。試験片は、焼入焼戻し後の試料から作製した。試験片形状は２ｍｍＵノッチシャルピー試験片であり、ノッチ方向は鍛伸方向に対して垂直な方向とした。得られたシャルピー衝撃値（Ｊ／ｃｍ2）を表３、表４に示す。焼入焼戻し後の室温でのシャルピー衝撃値が２０Ｊ／ｃｍ2以上のものを高靱性であると評価した。
(Toughness)
The toughness was evaluated by a Charpy impact test at room temperature. Test pieces were prepared from samples after quenching and tempering. The test piece shape was a 2 mm U-notch Charpy test piece, and the notch direction was perpendicular to the forging direction. The obtained Charpy impact values (J/ cm2 ) are shown in Tables 3 and 4. Those having a Charpy impact value of 20 J/ cm2 or more at room temperature after quenching and tempering were evaluated as having high toughness.
（軟化抵抗性）
軟化抵抗性は、焼入焼戻し後の試料を６００℃で１００時間保持、空冷した後、室温での硬さをロックウェル硬さ試験機で測定することで評価した。結果を表３、表４に高温保持後の硬さ（ＨＲＣ）として示す。焼入焼戻し後に６００℃で１００ｈ保持後の室温での硬さが３２．０ＨＲＣ以上のものを高軟化抵抗性であると評価した。
(Softening resistance)
The softening resistance was evaluated by holding the quenched and tempered samples at 600°C for 100 hours, air-cooling, and then measuring the hardness at room temperature with a Rockwell hardness tester. The results are shown in Tables 3 and 4 as hardness (HRC) after high temperature holding. Samples that had a hardness of 32.0 HRC or more at room temperature after holding at 600°C for 100 hours after quenching and tempering were evaluated as having high softening resistance.
発明鋼Ｎｏ．１～４４は、いずれも熱間工具鋼は、鋼塊状態にてグリーブル試験を１１００℃で実施したときの絞りが７０％以上の高熱間加工性を示し、焼入焼戻し後の室温での熱伝導率が２５．０Ｗ／ｍ・Ｋ以上の高熱伝導率であって、焼入焼戻し後の室温での硬さが４８．０ＨＲＣ以上と高硬度であって、焼入焼戻し後の室温でのシャルピー衝撃値が２０Ｊ／ｃｍ2以上の高靱性であって、焼入焼戻し後に６００℃で１００ｈ保持後の室温での硬さが３２．０ＨＲＣ以上といった高軟化抵抗性を示すものとなり、これらの全ての特性を兼ね備えるものとなった。 All of the hot work tool steels of the invention steels No. 1 to 44 exhibit high hot workability with a reduction of 70% or more when a Gleeble test is performed at 1100 ° C. in the steel ingot state, a high thermal conductivity of 25.0 W / m · K or more at room temperature after quenching and tempering, a high hardness of 48.0 HRC or more at room temperature after quenching and tempering, a high toughness of 20 J / cm 2 or more at room temperature after quenching and tempering, and a high softening resistance of 32.0 HRC or more at room temperature after quenching and tempering after holding at 600 ° C. for 100 h.
比較鋼Ｎｏ．４５では、Ｃ量が少なく、十分な焼入焼戻硬さが得られなかった。
比較鋼Ｎｏ．４６では、Ｃ量が過剰であり、熱間加工性が悪く、また十分な靭性が得られなかった。
比較鋼Ｎｏ．４７では、Ｓｉ量が過剰であり、熱伝導率が低下した。
比較鋼Ｎｏ．４８では、Ｍｎ量が過剰であり、熱伝導率が低下した。
比較鋼Ｎｏ．４９では、Ｃｒ量が少なく、マルテンサイトの割合が低かったので、十分な靭性が得られなかった。
比較鋼Ｎｏ．５０では、Ｃｒ量が過剰であり、熱伝導率が低下し、軟化抵抗性も低下した。
比較鋼Ｎｏ．５１では、Ｃｕ量が少なく、マルテンサイトの割合が低かったので、十分な靭性が得られなかった。
比較鋼Ｎｏ．５２では、Ｃｕ量が過剰であり、熱伝導率が低下した。
比較鋼Ｎｏ．５３では、Ｎｉ量が過剰であり、熱伝導率が低下した。
比較鋼Ｎｏ．５４では、Ｍｏ量が過剰であり、熱伝導率が低下した。
比較鋼Ｎｏ．５５では、Ｗ量が過剰であり、熱伝導率が低下した。
比較鋼Ｎｏ．５６では、Ｍｏ＋１／２Ｗの量が少なく、十分な焼入焼戻硬さが得られなかった。
比較鋼Ｎｏ．５７では、Ｍｏ＋１／２Ｗの量が過剰であり、熱伝導率が低下した。
比較鋼Ｎｏ．５８では、Ｖ量が少なく、十分な焼入焼戻硬さが得られなかった。
比較鋼Ｎｏ．５９では、Ｖ量が過剰であり、熱伝導率が低下した。
比較鋼Ｎｏ．６０では、Ｎ量が過剰であり、熱間加工性が悪化した。
比較鋼Ｎｏ．６１では、Ｏ量が過剰であり、熱間加工性が悪化した。
比較鋼Ｎｏ．６２では、Ｔｉ量が過剰であり、十分な靭性が得られなかった。
比較鋼Ｎｏ．６３では、Ａｌ量が過剰であり、熱間加工性が悪く、また十分な靭性が得られなかった。
比較鋼Ｎｏ．６４では、Ｂが含有されておらず、マルテンサイトの割合が低かったので、十分な靱性が得られなかった。
比較鋼Ｎｏ．６５では、Ｂ量が過剰であり、熱間加工性が悪く、また十分な靭性が得られなかった。
比較鋼Ｎｏ．６６では、Ｂ＋Ｏ＋Ｎの量が過剰であり、熱間加工性が悪化した。
比較鋼Ｎｏ．６７では、成分組成は本発明の範囲を充たしているものの、式Ｋの値が低いものであるところ、熱間加工性が低いものであった。
In the comparative steel No. 45, the C content was small, and sufficient quench-tempered hardness was not obtained.
In the comparative steel No. 46, the C content was excessive, the hot workability was poor, and sufficient toughness was not obtained.
In the comparative steel No. 47, the amount of Si was excessive, and the thermal conductivity was reduced.
In the comparative steel No. 48, the Mn amount was excessive, and the thermal conductivity was reduced.
In comparative steel No. 49, the Cr content was small and the proportion of martensite was low, so sufficient toughness was not obtained.
In the comparative steel No. 50, the Cr amount was excessive, and the thermal conductivity was decreased and the softening resistance was also decreased.
In comparative steel No. 51, the Cu content was small and the proportion of martensite was low, so sufficient toughness was not obtained.
In the comparative steel No. 52, the Cu amount was excessive, and the thermal conductivity was reduced.
In the comparative steel No. 53, the amount of Ni was excessive, and the thermal conductivity was reduced.
In the comparative steel No. 54, the amount of Mo was excessive, and the thermal conductivity was reduced.
In the comparative steel No. 55, the amount of W was excessive, and the thermal conductivity was reduced.
In the comparative steel No. 56, the amount of Mo+1/2W was small, and sufficient quench-tempered hardness was not obtained.
In the comparative steel No. 57, the amount of Mo+1/2W was excessive, and the thermal conductivity was reduced.
In the comparative steel No. 58, the amount of V was small, and sufficient quench-tempered hardness was not obtained.
In the comparative steel No. 59, the amount of V was excessive, and the thermal conductivity was reduced.
In the comparative steel No. 60, the N amount was excessive, and the hot workability was deteriorated.
In the comparative steel No. 61, the amount of O was excessive, and the hot workability was deteriorated.
In comparative steel No. 62, the Ti content was excessive, and sufficient toughness was not obtained.
In the comparative steel No. 63, the amount of Al was excessive, and the hot workability was poor and sufficient toughness was not obtained.
In the comparative steel No. 64, since B was not contained and the proportion of martensite was low, sufficient toughness was not obtained.
In the comparative steel No. 65, the B content was excessive, and the hot workability was poor and sufficient toughness was not obtained.
In the comparative steel No. 66, the amount of B+O+N was excessive, and the hot workability was deteriorated.
In the comparative steel No. 67, the composition satisfies the range of the present invention, but the value of the formula K is low, and the hot workability is poor.
Claims (6)
Ｂ＋Ｏ＋Ｎ：０．０４２０％以下を充たし、さらに、次の式に示すＫの値が１５．６以上であること、を特徴とする熱間工具鋼。
式：Ｋ＝３６．０４－１２．６５Ｃ－１．５８Ｍｏ－０．７９Ｗ－９．３４Ｍｎ－１９．０１Ａｌ＋０．６９Ｎｉ－０．３４Ｃｕ
（ただし、この式の右辺の各元素記号には、鋼を構成する元素成分の百分率の数値を代入する。） a steel containing, in mass %, C: more than 0.35% to 0.70%, Si: 0.01% to 1.20%, Mn: 0.01% to 1.50%, Cr: 0.35% to 4.00%, Cu: 0.10% to 2.50%, Ni: 0.10% to 2.99%, V: more than 0.10% to 0.55%, B: 0.0001% to 0.0100%, and O: 0.0050% or less, and containing either one or both of Mo and W, and further containing Mo: 3.00% or less, W: 6.00% or less, Mo+1/2W: 0.50% to 3.00%, with the balance being Fe and unavoidable impurities;
A hot work tool steel characterized in that B+O+N is 0.0420% or less, and further, the value of K represented by the following formula is 15.6 or more.
Formula: K=36.04-12.65C-1.58Mo-0.79W-9.34Mn-19.01Al+0.69Ni-0.34Cu
(However, the percentage of each element that makes up the steel is substituted for each element symbol on the right side of this formula.)
Ｂ＋Ｏ＋Ｎ：０．０４２０％以下を充たし、さらに、次の式に示すＫの値が１５．６以上である熱間工具鋼。
式：Ｋ＝３６．０４－１２．６５Ｃ－１．５８Ｍｏ－０．７９Ｗ－９．３４Ｍｎ－１９．０１Ａｌ＋０．６９Ｎｉ－０．３４Ｃｕ
（ただし、この式の右辺の各元素記号には、鋼を構成する元素成分の百分率の数値を代入する。） In addition to the components described in claim 1, further containing N: 0.0001% to 0.0400%,
A hot work tool steel satisfying B+O+N: 0.0420% or less, and further having a K value represented by the following formula of 15.6 or more.
Formula: K=36.04-12.65C-1.58Mo-0.79W-9.34Mn-19.01Al+0.69Ni-0.34Cu
(However, the percentage of each element that makes up the steel is substituted for each element symbol on the right side of this formula.)
Ｂ＋Ｏ＋Ｎ：０．０４２０％以下を充たし、さらに、次の式に示すＫの値が１５．６以上である熱間工具鋼。
式：Ｋ＝３６．０４－１２．６５Ｃ－１．５８Ｍｏ－０．７９Ｗ－９．３４Ｍｎ－１９．０１Ａｌ＋０．６９Ｎｉ－０．３４Ｃｕ
（ただし、この式の右辺の各元素記号には、鋼を構成する元素成分の百分率の数値を代入する。） In addition to the components according to claim 1 or 2, the composition further contains Ti: 0.001% to 0.150%,
A hot work tool steel satisfying B+O+N: 0.0420% or less, and further having a K value represented by the following formula of 15.6 or more.
Formula: K=36.04-12.65C-1.58Mo-0.79W-9.34Mn-19.01Al+0.69Ni-0.34Cu
(However, the percentage of each element that makes up the steel is substituted for each element symbol on the right side of this formula.)
Ｂ＋Ｏ＋Ｎ：０．０４２０％以下を充たし、さらに、次の式に示すＫの値が１５．６以上である熱間工具鋼。
式：Ｋ＝３６．０４－１２．６５Ｃ－１．５８Ｍｏ－０．７９Ｗ－９．３４Ｍｎ－１９．０１Ａｌ＋０．６９Ｎｉ－０．３４Ｃｕ
（ただし、この式の右辺の各元素記号には、鋼を構成する元素成分の百分率の数値を代入する。） In addition to the components according to any one of claims 1 to 3, further containing Al: 0.001% or more and 0.200% or less,
A hot work tool steel satisfying B+O+N: 0.0420% or less, and further having a K value represented by the following formula of 15.6 or more.
Formula: K=36.04-12.65C-1.58Mo-0.79W-9.34Mn-19.01Al+0.69Ni-0.34Cu
(However, the percentage of each element that makes up the steel is substituted for each element symbol on the right side of this formula.)
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000328195A (en) | 1999-05-20 | 2000-11-28 | Daido Steel Co Ltd | Tool steel excellent in short time hardenability |
| JP2008121032A (en) | 2006-11-08 | 2008-05-29 | Daido Steel Co Ltd | Die steel superior in spheroidizing annealing property and hardenability |
| JP2008169411A (en) | 2007-01-10 | 2008-07-24 | Daido Steel Co Ltd | Steel for die materials |
| JP2009013465A (en) | 2007-07-04 | 2009-01-22 | Daido Steel Co Ltd | Tool steel, member for forming using the same, and method for verifying quality of tool steel |
| JP2009024260A (en) | 2002-04-03 | 2009-02-05 | Industeel France | Bulk steel for production of injection mold for plastic material or for production of component for working metal |
| JP2011074427A (en) | 2009-09-29 | 2011-04-14 | Daido Steel Co Ltd | Hollow drill steel rod |
-
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000328195A (en) | 1999-05-20 | 2000-11-28 | Daido Steel Co Ltd | Tool steel excellent in short time hardenability |
| JP2009024260A (en) | 2002-04-03 | 2009-02-05 | Industeel France | Bulk steel for production of injection mold for plastic material or for production of component for working metal |
| JP2008121032A (en) | 2006-11-08 | 2008-05-29 | Daido Steel Co Ltd | Die steel superior in spheroidizing annealing property and hardenability |
| JP2008169411A (en) | 2007-01-10 | 2008-07-24 | Daido Steel Co Ltd | Steel for die materials |
| JP2009013465A (en) | 2007-07-04 | 2009-01-22 | Daido Steel Co Ltd | Tool steel, member for forming using the same, and method for verifying quality of tool steel |
| JP2011074427A (en) | 2009-09-29 | 2011-04-14 | Daido Steel Co Ltd | Hollow drill steel rod |
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