JP4926764B2 - High wear resistance, high toughness, high speed tool steel and method for producing the same - Google Patents
High wear resistance, high toughness, high speed tool steel and method for producing the same Download PDFInfo
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- JP4926764B2 JP4926764B2 JP2007056722A JP2007056722A JP4926764B2 JP 4926764 B2 JP4926764 B2 JP 4926764B2 JP 2007056722 A JP2007056722 A JP 2007056722A JP 2007056722 A JP2007056722 A JP 2007056722A JP 4926764 B2 JP4926764 B2 JP 4926764B2
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- 229910001315 Tool steel Inorganic materials 0.000 title claims description 14
- 238000004519 manufacturing process Methods 0.000 title claims description 5
- 239000002245 particle Substances 0.000 claims description 16
- 229910000831 Steel Inorganic materials 0.000 claims description 14
- 238000005242 forging Methods 0.000 claims description 14
- 239000010959 steel Substances 0.000 claims description 13
- 239000012535 impurity Substances 0.000 claims description 7
- 229910052720 vanadium Inorganic materials 0.000 description 18
- 229910052750 molybdenum Inorganic materials 0.000 description 15
- 229910052710 silicon Inorganic materials 0.000 description 14
- 229910052721 tungsten Inorganic materials 0.000 description 13
- 238000010438 heat treatment Methods 0.000 description 12
- 229910052748 manganese Inorganic materials 0.000 description 12
- 229910052804 chromium Inorganic materials 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 10
- 229910052799 carbon Inorganic materials 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 238000005520 cutting process Methods 0.000 description 6
- 150000001247 metal acetylides Chemical class 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 238000001513 hot isostatic pressing Methods 0.000 description 3
- 238000000137 annealing Methods 0.000 description 2
- 239000002775 capsule Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009863 impact test Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000004663 powder metallurgy Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- 229910000997 High-speed steel Inorganic materials 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000007542 hardness measurement Methods 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
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Description
本発明は、粉末冶金法による耐摩耗、耐割損、および耐熱用途に適したロール用高耐摩耗、高靱性高速度工具鋼およびその製造方法に関するものである。 The present invention relates to a high wear resistance, high toughness, high speed tool steel for rolls suitable for wear resistance, crack resistance, and heat resistance by powder metallurgy, and a method for producing the same.
従来、耐摩耗性、耐熱性向上を狙いとして切削工具用ハイスなどではＣｏが添加されている。このＣｏ添加は耐摩耗性、耐熱性を容易に得られるため、切削工具などの高速度工具鋼には有効であるが、しかしながら、ロールなどの用途では著しい靱性低下により、使用時の早期割損を引き起こして生産性を阻害する要因となっている。さらに、Ｃｏは高価であり、ロール加工時の切削性を悪化し加工コストを引上げる要因にもなっている。 Conventionally, Co has been added to high speed cutting tools for the purpose of improving wear resistance and heat resistance. This addition of Co is effective for high-speed tool steels such as cutting tools because wear resistance and heat resistance can be easily obtained. However, in applications such as rolls, due to a significant decrease in toughness, early breakage during use This is a factor that inhibits productivity. Furthermore, Co is expensive, and it is a factor that deteriorates the machinability at the time of roll processing and increases the processing cost.
そこで、例えば特表平６−５０９８４３号公報（特許文献１）に開示されているように、粉末冶金で製造した重量％で、Ｃ：２．２〜２．７％、Ｓｉ：微量〜最高１．０％、Ｍｎ：微量〜最高１．０％、Ｃｒ：３．５〜４．５％、Ｍｏ：２．５〜４．５％、Ｗ：２．５〜４．５％、Ｖ：７．５〜９．５％、及び実質的に鉄からなる化学組成を有する高速度鋼が提案されている。 Therefore, for example, as disclosed in JP-T-6-509843 (Patent Document 1), the weight percentage produced by powder metallurgy is C: 2.2 to 2.7%, Si: trace amount to maximum 1 0.0%, Mn: Trace amount to maximum 1.0%, Cr: 3.5-4.5%, Mo: 2.5-4.5%, W: 2.5-4.5%, V: 7 High speed steels having a chemical composition of 0.5 to 9.5% and substantially consisting of iron have been proposed.
また、特開平６−２５６９０７号公報（特許文献２）には、重量％で、Ｃ：１．０〜２．０％、Ｓｉ：０．１〜１．０％、Ｍｎ：１．０％以下、Ｃｒ：３．５〜５．０％、Ｍｏ：２．０〜１２．０％、Ｗ：４．０〜２０．０％およびＶ：２．７〜５．０％を含有し、Ｎ：２００ｐｐｍ以下であって、残部が実質上Ｆｅからなる高靱性高バナジウム工具鋼が提案されているが、しかしながら、特許文献１の場合は、Ｗ添加が不十分で、耐摩耗性が不足し、また、特許文献２の場合は、Ｖ添加が不十分で、耐摩耗性が不足するという問題がある。 Japanese Patent Application Laid-Open No. 6-256907 (Patent Document 2) describes C: 1.0 to 2.0%, Si: 0.1 to 1.0%, and Mn: 1.0% or less by weight. , Cr: 3.5-5.0%, Mo: 2.0-12.0%, W: 4.0-20.0% and V: 2.7-5.0%, N: A high toughness high vanadium tool steel having a balance of not more than 200 ppm and the balance being substantially Fe has been proposed. However, in the case of Patent Document 1, the addition of W is insufficient and the wear resistance is insufficient. In the case of Patent Document 2, there is a problem that V addition is insufficient and wear resistance is insufficient.
また、特許第２７６０００１号公報（特許文献３）に開示されているように、重量％で、Ｃ：０．４〜３．０％、Ｓｉ：０．０１〜２．０％、Ｃｒ：１〜８％、Ｍｏ：２．３％以下であって、２Ｍｏ＋Ｗ：４〜１５％、Ｖ：２〜１０％、Ｎ：５０ｐｐｍ以下、及び残部が実質的にＦｅからなる高速度工具鋼が提案されているが、この高速度工具鋼では靱性などの機械的特性が劣化するという問題がある。 Further, as disclosed in Japanese Patent No. 2760001 (Patent Document 3), C: 0.4 to 3.0%, Si: 0.01 to 2.0%, Cr: 1 to 1% by weight. 8%, Mo: 2.3% or less, 2Mo + W: 4-15%, V: 2-10%, N: 50 ppm or less, and a high-speed tool steel consisting essentially of Fe is proposed. However, this high-speed tool steel has a problem that mechanical properties such as toughness deteriorate.
また、特許第２６８９５１３号公報（特許文献４）には、重量％で、Ｃ：０．２〜３．５％、Ｓｉ：３．０％以下、Ｍｎ：２．０％以下、Ｃｒ：１．０〜２０．０％、Ｍｏ：０．０１〜１５．０％、Ｗ：１．５〜３０．０％、Ｖ：０．５〜１０．０％、Ｃｏ：２０．０％以下、Ｏ：０．００５％以下、Ｓ：０．０１％以下、残部が実質的にＦｅからなる低酸素粉末高速度工具鋼が提案されているが、低酸素粉末工具鋼では低酸素によるアトマイズやＨＩＰ工程でのコストアップとなる。 Further, in Japanese Patent No. 2689513 (Patent Document 4), by weight, C: 0.2 to 3.5%, Si: 3.0% or less, Mn: 2.0% or less, Cr: 1. 0 to 20.0%, Mo: 0.01 to 15.0%, W: 1.5 to 30.0%, V: 0.5 to 10.0%, Co: 20.0% or less, O: A low-oxygen powder high-speed tool steel consisting of 0.005% or less, S: 0.01% or less, and the balance substantially consisting of Fe has been proposed. Cost increase.
また、特開平６−２７９９４３号公報（特許文献５）に開示されているように、重量％で、Ｃ：１〜２％、Ｓｉ：０．１〜１％、Ｍｎ：０．５％以下、Ｎｉ：０．５％以下、Ｃｒ：２〜６％、Ｍｏ：１〜１０％、Ｗ：３〜１３％、Ｖ：２〜７％、Ｃｏ：５〜１１％、残部がＦｅおよび不可避不純物からなる高硬度・高靱性粉末高速度工具鋼や特開平８−４１５９２号公報（特許文献６）の高Ｖ高速度工具鋼が提案されているが、いずれも上述したＣｏ添加により靱性が劣化する。 Further, as disclosed in JP-A-6-279943 (Patent Document 5), by weight%, C: 1-2%, Si: 0.1-1%, Mn: 0.5% or less, Ni: 0.5% or less, Cr: 2-6%, Mo: 1-10%, W: 3-13%, V: 2-7%, Co: 5-11%, the balance from Fe and inevitable impurities The high hardness and high toughness powder high-speed tool steel and the high V high-speed tool steel disclosed in JP-A-8-41592 (Patent Document 6) have been proposed.
また、特許第２９６２９６９号公報（特許文献７）に開示されているように、重量％で、Ｃ：１．５〜２．６％、Ｓｉ：１．０％以下、Ｍｎ：０．５％以下、Ｃｒ：３〜５％未満、Ｗ：３〜１５％、Ｍｏ：５〜１０％、Ｖ：４〜７％、ただし、Ｗ当量としてＷ＋２Ｍｏ：２０〜３０％、残部Ｆｅおよび不可避不純物からなる発錆性に優れた粉末ハイスが提案されているが、Ｗ＋２Ｍｏの値が高く、靱性が劣化する。 Further, as disclosed in Japanese Patent No. 29629969 (Patent Document 7), by weight, C: 1.5 to 2.6%, Si: 1.0% or less, Mn: 0.5% or less Cr: 3 to less than 5%, W: 3 to 15%, Mo: 5 to 10%, V: 4 to 7%, where W equivalent is W + 2Mo: 20 to 30%, balance Fe and inevitable impurities A powder HSS with excellent rust properties has been proposed, but the value of W + 2Mo is high and the toughness deteriorates.
また、特許第２９９９６５５号公報（特許文献８）に開示されているように、重量％で、Ｃ：０．７〜２．５％、Ｓｉ：０．１〜２．０％、Ｍｎ：１．５％以下、Ｃｒ：３．０〜６．０％、Ｖ：０．８〜２５．０％、Ｐ：０．００９％未満を含有し、Ｍｏ：３．０〜１０．０％又はＷ：１．０〜２０．０％のいずれか１種又は２種を含有し、残部Ｆｅおよび不可避不純物からなる高靱性粉末ハイスが提案されているが、Ｐ低減で製造コストアップとなるという問題がある。
上述したような引用文献では、いずれもロールなどの用途では著しい靱性低下により、使用時の早期割損を引き起こして、生産性を阻害する要因となっている。特にＣｏ添加の場合はＣｏが高価であり、ロール加工時の切削性を悪化し加工コストを引上げる要因にもなっている。 In the cited references as described above, any of the applications such as rolls causes a significant deterioration in toughness, which causes early breakage during use and becomes a factor that hinders productivity. In particular, when Co is added, Co is expensive, which is a factor that deteriorates the machinability at the time of roll processing and increases the processing cost.
上述したような問題を解消するために、発明者らは鋭意開発を進めた結果、Ｃｏについては基地組織に固溶して、耐摩耗性、耐熱性を高めることが出来るが靱性を劣化させる。この問題に対し、本発明はＣｏを無添加とし、Ｖ量およびＷ量を大幅に増やすことで、靱性を改善しつつ、優れた耐摩耗性、耐熱性を保持することができ、また、熱間加工温度と鍛錬比を最適化し、炭化物サイズと面積率を制御することで耐摩耗性、耐熱性に優れたロール用鋼を低コストで提供することができた。 In order to solve the above-described problems, the inventors have made extensive developments. As a result, Co can be dissolved in the base structure to improve wear resistance and heat resistance, but toughness is deteriorated. In order to solve this problem, the present invention eliminates Co and significantly increases the amounts of V and W to improve toughness while maintaining excellent wear resistance and heat resistance. By optimizing the hot working temperature and forging ratio and controlling the carbide size and area ratio, we were able to provide steel for rolls with excellent wear resistance and heat resistance at low cost.
その発明の要旨とするところは、
（１）質量％で、Ｃ：２．０〜２．２％、Ｓｉ：０．５％以下、Ｍｎ：０．５％以下、Ｃｒ：３．０〜５．０％、Ｍｏ：３．０〜６．０％、Ｗ：６．０〜９．０％、Ｖ：６．０〜８．０％、を含有し、残部Ｆｅおよび不可避的不純物よりなり、かつ２Ｍｏ＋Ｗ：１５％超〜２０％未満であることを特徴とする高耐摩耗、高靱性高速度工具鋼。
（２）前記（１）に記載の鋼であって、炭化物面積率が２０〜３０％、炭化物平均粒径が４μｍ以下であることを特徴とする高耐摩耗、高靱性高速度工具鋼。
The gist of the invention is that
(1) By mass%, C: 2.0 to 2.2%, Si: 0.5% or less, Mn: 0.5% or less, Cr: 3.0 to 5.0%, Mo: 3.0 -6.0%, W: 6.0-9.0%, V: 6.0-8.0%, the balance consisting of Fe and inevitable impurities, and 2Mo + W: more than 15% to 20% High wear resistance, high toughness, high speed tool steel characterized by being less than.
(2) The steel according to (1) above, having a carbide area ratio of 20 to 30% and a carbide average particle size of 4 μm or less, a high wear resistance, high toughness and high speed tool steel.
（３）質量％で、Ｃ：２．０〜２．２％、Ｓｉ：０．５％以下、Ｍｎ：０．５％以下、Ｃｒ：３．０〜５．０％、Ｍｏ：３．０〜６．０％、Ｗ：６．０〜９．０％、Ｖ：６．０〜８．０％、を含有し、残部Ｆｅおよび不可避的不純物よりなり、かつ２Ｍｏ＋Ｗ：１５％超〜２０％未満である鋼を１１２０〜１１８０℃に加熱し、鍛錬比８以上の熱間加工後焼鈍することを特徴とする高耐摩耗、高靱性高速度工具鋼の製造方法にある。 (3) By mass%, C: 2.0 to 2.2%, Si: 0.5% or less, Mn: 0.5% or less, Cr: 3.0 to 5.0%, Mo: 3.0 -6.0%, W: 6.0-9.0%, V: 6.0-8.0%, the balance consisting of Fe and inevitable impurities, and 2Mo + W: more than 15% to 20% It is in the manufacturing method of the high wear resistance, the high toughness high speed tool steel characterized by heating the steel which is less than 1120-1180 degreeC, and annealing after hot working with a forging ratio 8 or more.
以上述べたように、本発明により耐摩耗性、耐熱性に優れたロール用鋼を低コストで提供でき、かつ耐割損性が改善されることで、生産性の向上、製品不良の低減に大きく寄与することができる極めて優れた効果を奏するものである。 As described above, according to the present invention, roll steel excellent in wear resistance and heat resistance can be provided at low cost, and the crack resistance is improved, thereby improving productivity and reducing product defects. There is an extremely excellent effect that can greatly contribute.
以下、本発明に係る成分組成の限定理由を説明する。
Ｃ：２．０〜２．２％
Ｃは、焼入れ焼戻し後の硬度確保のために必要で、Ｃｒ，Ｍｏ，Ｖ，Ｗと炭化物を形成し耐摩耗に寄与する元素である。しかし、２．０％未満ではその効果が不十分であり、また、２．２％を超えると炭化物が粗大になり靱性を著しく劣化させる。従って、その範囲を２．０〜２．２％とした。
Hereinafter, the reasons for limiting the component composition according to the present invention will be described.
C: 2.0-2.2%
C is an element that is necessary for securing hardness after quenching and tempering, and forms carbides with Cr, Mo, V, and W and contributes to wear resistance. However, if it is less than 2.0%, the effect is insufficient, and if it exceeds 2.2%, the carbide becomes coarse and the toughness is significantly deteriorated. Therefore, the range was set to 2.0 to 2.2%.
Ｓｉ：０．５％以下
Ｓｉは、脱酸剤として添加するとともに、焼入れ性にも有効である。しかし、０．５％を超えると残留オーステナイトが分解しにくくなり経年変化が大きくなる。従って、その上限を０．５％とした。
Ｍｎ：０．５％以下
Ｍｎは、Ｓｉと同様に、脱酸剤として添加するとともに、焼入れ性にも有効である。しかし、０．５％を超えると靱性を劣化させることから、その上限を０．５％とした。
Si: 0.5% or less Si is added as a deoxidizer and is also effective in hardenability. However, if it exceeds 0.5%, the retained austenite becomes difficult to decompose and the secular change becomes large. Therefore, the upper limit was made 0.5%.
Mn: 0.5% or less Mn is added as a deoxidizing agent as well as Si, and is also effective in hardenability. However, if it exceeds 0.5%, the toughness deteriorates, so the upper limit was made 0.5%.
Ｃｒ：３．０〜５．０％
Ｃｒは、焼入れ性と耐摩耗性の確保に必要な元素である。しかし、３．０％未満ではその効果が十分に得られない。また、５．０％を超えると炭化物が粗大化して靱性が悪化することから、その範囲を３．０〜５．０％とした。
Cr: 3.0-5.0%
Cr is an element necessary for ensuring hardenability and wear resistance. However, if it is less than 3.0%, the effect cannot be sufficiently obtained. Moreover, since carbide will coarsen and toughness will deteriorate when it exceeds 5.0%, the range was made into 3.0 to 5.0%.
Ｍｏ：３．０〜６．０％
Ｍｏは、析出炭化物による耐摩耗性を改善する元素である。しかし、３．０％未満ではその効果が十分に得られない。また、６．０％を超えると析出炭化物が凝集し、靱性が低下する。従って、その範囲を３．０〜６．０％とした。
Mo: 3.0-6.0%
Mo is an element that improves wear resistance due to precipitated carbides. However, if it is less than 3.0%, the effect cannot be sufficiently obtained. On the other hand, if it exceeds 6.0%, the precipitated carbides aggregate and the toughness decreases. Therefore, the range was made 3.0 to 6.0%.
Ｗ：６．０〜９．０％
Ｗは、Ｍｏと同様に、析出炭化物による耐摩耗性を改善する元素である。しかし、６．０％未満ではその効果が十分に得られない。また、９．０％を超えると析出炭化物が凝集し、靱性が低下する。従って、その範囲を６．０〜９．０％とした。
W: 6.0-9.0%
W, like Mo, is an element that improves wear resistance due to precipitated carbides. However, if it is less than 6.0%, the effect cannot be sufficiently obtained. On the other hand, if it exceeds 9.0%, the precipitated carbide aggregates and the toughness decreases. Therefore, the range was made 6.0 to 9.0%.
Ｖ：６．０〜８．０％
Ｖは、析出炭化物による耐摩耗性の改善と高温熱処理時の結晶粒粗大化抑制と高温での軟化抵抗性の改善を図る元素である。しかし、６．０％未満ではその効果が十分に得られない。また、８．０％を超えると析出炭化物が粗大化して、被削性と靱性が低下する。従って、その範囲を６．０〜８．０％とした。
V: 6.0-8.0%
V is an element that improves wear resistance by precipitated carbide, suppresses coarsening of grains during high-temperature heat treatment, and improves softening resistance at high temperatures. However, if it is less than 6.0%, the effect cannot be sufficiently obtained. On the other hand, if it exceeds 8.0%, the precipitated carbide is coarsened and the machinability and toughness are lowered. Therefore, the range was made 6.0 to 8.0%.
２Ｍｏ＋Ｗ：１５％超〜２０％未満
Ｗは、Ｍｏの等量的には２倍の作用を有し、２Ｍｏ＋Ｗが１５％以下では、析出炭化物による耐摩耗性の改善が十分でなく、また、２０％以上では析出炭化物が凝集し、靱性が低下する。従って、その範囲を１５％超〜２０％未満とした。
2Mo + W: more than 15% to less than 20% W has an effect equivalent to twice that of Mo, and if 2Mo + W is 15% or less, the improvement in wear resistance by precipitated carbide is not sufficient. If it is at least%, the precipitated carbides will aggregate and the toughness will decrease. Therefore, the range is made more than 15% to less than 20%.
加熱温度：１１２０〜１１８０℃
上述した鋼の加熱温度を１１２０〜１１８０℃としたのは、１１２０℃未満では析出炭化物面積率および炭化物平均粒径を最適範囲に制御するに十分な温度でなく、また、１１８０℃を超える温度は必要としないことから、その範囲を１１２０〜１１８０℃とした。
Heating temperature: 1120-1180 ° C
The heating temperature of the steel described above is set to 1120 to 1180 ° C. If the temperature is less than 1120 ° C., the temperature is not sufficient to control the precipitated carbide area ratio and carbide average particle size within the optimum range, and the temperature exceeding 1180 ° C. Since it is not necessary, the range was set to 1120 to 1180 ° C.
鍛錬比ｓ：８以上
鍛錬比ｓを８以上としたのは、上記鋼の加熱温度との関係から８未満では、上記のように、Ｖ，Ｗを大幅に増加させたことから、一次炭化物が粗大になり、炭化物面積率を２０％〜３０％、炭化物平均粒径４μｍ以下の炭化物が得られないことから、その下限を８とした。
Forging ratio s: 8 or more The forging ratio s was set to 8 or more because the V and W were greatly increased as described above when the ratio was less than 8 because of the relationship with the heating temperature of the steel. Since it becomes coarse and a carbide having a carbide area ratio of 20% to 30% and a carbide average particle size of 4 μm or less cannot be obtained, the lower limit is set to 8.
上記した加熱温度において鍛錬比ｓを８以上の条件での熱間加工を行い、ロールに加工するために、その後８００〜９００℃の温度で焼鈍した。焼鈍温度を８００℃以上としたのは、一次炭化物を固溶させるためである。しかし、９００℃を超えると炭化物の粗大化が進むため、その上限を９００℃とした。この鋼を１１００〜１２００℃の温度で焼入れ、５００〜６００℃の温度で焼戻し、この操作を２〜４回実施する。その結果、以下述べる炭化物面積率および炭化物平均粒径を得ることができた。 In order to perform the hot working on the forging ratio s at the above heating temperature under the condition of 8 or more and to process into a roll, it was subsequently annealed at a temperature of 800 to 900 ° C. The reason why the annealing temperature is set to 800 ° C. or higher is to dissolve the primary carbide. However, when the temperature exceeds 900 ° C., the coarsening of the carbide proceeds, so the upper limit was set to 900 ° C. This steel is quenched at a temperature of 1100 to 1200 ° C., tempered at a temperature of 500 to 600 ° C., and this operation is performed 2 to 4 times. As a result, the following carbide area ratio and carbide average particle diameter could be obtained.
炭化物面積率：２０〜３０％
炭化物面積率は、耐摩耗性を確保するための必要な条件である。しかし、２０％未満ではその効果が十分でなく、また、３０％を超えると靱性が劣化する。従って、その範囲を２０〜３０％とした。好ましくは２５〜３０％とする。
炭化物平均粒径：４μｍ以下
炭化物平均粒径は、靱性を確保するための必要な条件である。しかし、４μｍを超えると靱性が劣化する。従って、その上限を４μｍとした。
Carbide area ratio: 20-30%
The carbide area ratio is a necessary condition for ensuring wear resistance. However, if it is less than 20%, the effect is not sufficient, and if it exceeds 30%, the toughness deteriorates. Therefore, the range was made 20-30%. Preferably it is 25 to 30%.
Carbide average particle size: 4 μm or less The carbide average particle size is a necessary condition for ensuring toughness. However, if it exceeds 4 μm, the toughness deteriorates. Therefore, the upper limit is set to 4 μm.
以下、本発明について実施例によって具体的に説明する。
表１に示す本発明鋼および比較鋼の成分組成の鋼を溶解し、溶湯を不活性ガス雰囲気によりガスアトマイズして粉末を得る。この粉末を１０００μｍ以下でふるい分けした後、カプセルに充填、密封し、１２２ＭＰａ、１１５０℃で７時間、ＨＩＰ（熱間静水圧プレス処理）処理を行った。このＨＩＰ処理済みカプセルを加熱炉にて、１１１５〜１１９０℃の温度範囲で加熱、鍛錬比５．５〜１３．２ｓで熱間鍛伸を行い、平角材とした後、８７０℃で焼鈍した。この平角材中周部よりシャルピー衝撃試験片（１０Ｒ２ｍｍＣノッチ）、大越式摩耗試験片（２５ｍｍ×５０ｍｍ×７ｍｍ）を割り出し、熱処理として１１８０℃焼入れした後５６０℃焼戻し×３回実施した後、各試験片を得た。
Hereinafter, the present invention will be specifically described with reference to examples.
The steel of the present invention and the comparative steel composition shown in Table 1 are melted, and the molten metal is gas atomized in an inert gas atmosphere to obtain powder. After sieving this powder to 1000 μm or less, the capsule was filled and sealed, and subjected to HIP (hot isostatic pressing) at 122 MPa and 1150 ° C. for 7 hours. The HIP-treated capsule was heated in a heating furnace in a temperature range of 1115 to 1190 ° C., hot forged at a forging ratio of 5.5 to 13.2 s to obtain a flat bar, and then annealed at 870 ° C. The Charpy impact test piece (10R2mmC notch) and the Ogoshi-type wear test piece (25mm x 50mm x 7mm) were indexed from the middle periphery of this flat bar, and after quenching at 1180 ° C as heat treatment, tempering at 560 ° C x 3 times, each test I got a piece.
この試験片の切削性、熱処理硬さ、シャルピー衝撃値および比摩耗量の評価を行った。切削性の評価方法としては、平角材（８０ｍｍ×１５０ｍｍ×２００ｍｍ）をフライスで径１２０ｍｍ、１２枚刃の工具を用いて切削した際の、切削工具刃先の平均摩耗幅が０．５ｍｍになるまでの切削距離で相対比較を行う。その測定条件としては、回転数：５００ｒｐｍ、送り速度：３００ｒｐｍ、切り込み量：１ｍｍで切削、その測定結果は比較例Ｎｏ．６の切削距離を１．０として、相対指数比較を行う。 The test piece was evaluated for machinability, heat treatment hardness, Charpy impact value, and specific wear. As an evaluation method of machinability, until the average wear width of the cutting tool edge becomes 0.5 mm when a flat material (80 mm × 150 mm × 200 mm) is cut with a miller with a diameter of 120 mm and a 12-flute tool Relative comparison is performed with the cutting distance. The measurement conditions were as follows: rotational speed: 500 rpm, feed rate: 300 rpm, cutting depth: 1 mm. The relative index comparison is performed with the cutting distance of 6 as 1.0.
硬さ測定方法としては、シャルピー衝撃試験片の平行部をロックウエル硬度計Ｃスケールで測定した。また、耐摩耗性試験としての大越式摩耗試験は、相手リングＳＣＭ４２０（硬さ８６ＨＲＢ）、荷重６１．８Ｎ、摩擦距離２００ｍｍ、摩擦速度２．４ｍ／ｓｅｃの条件で試験を実施し、比摩耗量を算出した。これら試験結果を表２に示す。なお、表１に示す炭化物の面積率と粒径は、コンピュータによる画像解析により算出した。 As a hardness measurement method, the parallel part of the Charpy impact test piece was measured with a Rockwell hardness meter C scale. In addition, the Ogoshi type wear test as a wear resistance test was carried out under the conditions of the mating ring SCM420 (hardness 86HRB), load 61.8N, friction distance 200mm, friction speed 2.4m / sec. Was calculated. These test results are shown in Table 2. The area ratio and particle size of the carbides shown in Table 1 were calculated by image analysis using a computer.
比較例Ｎｏ．６は成分組成としてのＭｎを除いて、Ｃ、Ｓｉ，Ｃｒ，Ｍｏは高く、Ｗ，Ｖが低く、かつＣｏを含有することから炭化物面積率も高く、また炭化物平均粒径も大きく、そのために切削性指数が小さく、かつシャルピー衝撃値が小さく靱性が劣る。比較例Ｎｏ．７は成分組成としてのＳｉ，Ｍｎを除いて、Ｃ，Ｗ，Ｖが低く、Ｃｒ，Ｍｏが高く、かつＣｏを含有することから炭化物面積率も高く、また炭化物平均粒径も大きいために、切削性指数が小さく、かつシャルピー衝撃値が小さく靱性が劣り、かつ比摩耗量が大きく耐摩耗性に劣る。 Comparative Example No. 6 is high in C, Si, Cr, Mo except for Mn as a component composition, W, V are low, and since it contains Co, the carbide area ratio is also high, and the carbide average particle size is also large. The machinability index is small, the Charpy impact value is small, and the toughness is inferior. Comparative Example No. 7 has low C, W, V, high Cr, Mo, and contains Co except for Si and Mn as the component composition, and has a high carbide area ratio and a large average particle size of carbide. The machinability index is small, the Charpy impact value is small, the toughness is inferior, the specific wear amount is large, and the wear resistance is inferior.
比較例Ｎｏ．８は成分組成としてのＣｒを除いて、Ｃ，Ｓｉ，Ｍｎ，Ｍｏが高く、Ｗ，Ｖが低く、かつＣｏを含有し鍛錬比が低いために、炭化物面積率も高く、また炭化物平均粒径も大きいために、切削性指数が小さく、かつシャルピー衝撃値が小さく靱性が劣り、かつ比摩耗量もやや大きく耐摩耗性に劣る。比較例Ｎｏ．９は成分組成としてのＣｒを除いて、Ｃ，Ｍｏ，Ｖが低く、Ｃ，Ｓｉ，Ｍｎ，Ｗが高く、かつＣｏを含有することから炭化物面積率も高く、また炭化物平均粒径も大きいために、切削性指数が小さく、かつシャルピー衝撃値が小さく靱性が劣る。 Comparative Example No. Except for Cr as the component composition, C, Si, Mn, Mo are high, W, V are low, and Co is contained and the forging ratio is low, so the carbide area ratio is also high, and the carbide average particle size is Therefore, the machinability index is small, the Charpy impact value is small, the toughness is inferior, the specific wear amount is slightly large, and the wear resistance is inferior. Comparative Example No. 9 is low in C, Mo, V, high in C, Si, Mn, W, and contains Co except for Cr as a component composition, and has a high carbide area ratio and a large average particle size of carbide. Furthermore, the machinability index is small, the Charpy impact value is small, and the toughness is inferior.
比較例Ｎｏ．１０は成分組成としてのＣ，Ｃｒを除いて、Ｓｉ，Ｍｎ，Ｖが高く、Ｍｏ，Ｗは低く、かつＣｏを含有することから炭化物面積率も低く、また炭化物平均粒径が大きいために、切削性指数が小さく、かつシャルピー衝撃値が小さく靱性が劣り、比摩耗量もやや大きく耐摩耗性に劣る。比較例Ｎｏ．１１は鍛伸加熱温度が高いために、炭化物面積率が高く、かつ炭化物平均粒径も大きく、シャルピー衝撃値が小さく靱性が劣る。 Comparative Example No. 10 is high in Si, Mn, V except for C and Cr as the component composition, Mo and W are low, and since it contains Co, the carbide area ratio is low, and the average particle size of the carbide is large. The machinability index is small, the Charpy impact value is small, the toughness is inferior, the specific wear amount is slightly large, and the wear resistance is inferior. Comparative Example No. Since No. 11 has a high forging and heating temperature, the carbide area ratio is high, the carbide average particle size is large, the Charpy impact value is small, and the toughness is inferior.
比較例Ｎｏ．１２は鍛伸加熱温度が高く、鍛錬比が低いために、炭化物面積率が高く、かつ炭化物平均粒径も大きいために、シャルピー衝撃値が小さく靱性が劣る。比較例Ｎｏ．１３は鍛伸加熱温度が低く、鍛錬比が低いために、炭化物面積率が高く、かつ炭化物平均粒径も大きく、シャルピー衝撃値が小さく靱性が劣る。 Comparative Example No. Since No. 12 has a high forging and heating temperature and a low forging ratio, the carbide area ratio is high and the average particle size of the carbide is also large, so the Charpy impact value is small and the toughness is inferior. Comparative Example No. Since No. 13 has a low forging and heating temperature and a low forging ratio, the carbide area ratio is high, the carbide average particle size is large, the Charpy impact value is small, and the toughness is inferior.
上述したように、Ｃｏを無添加とし、Ｖ量を大幅に増やすことで、靱性を改善しつつ、優れた耐摩耗性、耐熱性を保持することを可能とし、さらに熱間加工温度と鍛錬比を最適化することで、炭化物サイズと炭化物面積率を制御して、高価なＣｏを使用せずに、耐摩耗性、耐熱性に優れたロール用鋼を低コストで提供することができ、かつ耐割損性の改善も可能となり、生産性の向上、製品不良の低減を図ることが出来た。
特許出願人 山陽特殊製鋼株式会社
代理人 弁理士 椎 名 彊
As mentioned above, it is possible to maintain excellent wear resistance and heat resistance while improving toughness by adding no Co and increasing the amount of V, and further, hot working temperature and forging ratio By controlling the carbide size and carbide area ratio, it is possible to provide roll steel with excellent wear resistance and heat resistance at low cost without using expensive Co, and It was also possible to improve the breakage resistance, improving productivity and reducing product defects.
Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina
Claims (3)
Ｃ：２．０〜２．２％、
Ｓｉ：０．５％以下、
Ｍｎ：０．５％以下、
Ｃｒ：３．０〜５．０％、
Ｍｏ：３．０〜６．０％、
Ｗ：６．０〜９．０％、
Ｖ：６．０〜８．０％、
を含有し、残部Ｆｅおよび不可避的不純物よりなり、かつ２Ｍｏ＋Ｗ：１５％超〜２０％未満であることを特徴とする高耐摩耗、高靱性高速度工具鋼。 % By mass
C: 2.0-2.2%
Si: 0.5% or less,
Mn: 0.5% or less,
Cr: 3.0-5.0%,
Mo: 3.0-6.0%,
W: 6.0-9.0%,
V: 6.0-8.0%,
, Balance Fe and inevitable impurities, and 2Mo + W: more than 15% to less than 20%, high wear resistance, high toughness, high speed tool steel.
Ｃ：２．０〜２．２％、
Ｓｉ：０．５％以下、
Ｍｎ：０．５％以下、
Ｃｒ：３．０〜５．０％、
Ｍｏ：３．０〜６．０％、
Ｗ：６．０〜９．０％、
Ｖ：６．０〜８．０％、
を含有し、残部Ｆｅおよび不可避的不純物よりなり、かつ２Ｍｏ＋Ｗ：１５％超〜２０％未満である鋼を１１２０〜１１８０℃に加熱し、鍛錬比８以上の熱間加工後焼鈍することを特徴とする高耐摩耗、高靱性高速度工具鋼の製造方法。 % By mass
C: 2.0-2.2%
Si: 0.5% or less,
Mn: 0.5% or less,
Cr: 3.0-5.0%,
Mo: 3.0-6.0%,
W: 6.0-9.0%,
V: 6.0-8.0%,
The steel is composed of the remainder Fe and inevitable impurities, and 2Mo + W: more than 15% to less than 20%, is heated to 1120 to 1180 ° C., and is annealed after hot working with a forging ratio of 8 or more. A high wear resistance, high toughness, high speed tool steel manufacturing method.
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