JP2022109485A - Wc-based cemented carbide and cutting tool including cemented carbide - Google Patents
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Abstract
Description
本発明は、ＷＣ基超硬合金に関する。 The present invention relates to a WC-based cemented carbide.
ＷＣ基超硬合金は機械的強度、耐熱疲労特性等に優れるため、切削工具として用いられている。一般的に高硬度鋼の加工に用いる超硬合金は、Ｖ、Ｃｒ、Ｔａといった粒成長抑制材を添加してＷＣ平均粒径を小さくして耐摩耗性をより高めたＷＣ基超硬合金が適用されている。一方、粒成長抑制材の添加量が多いと靭性が低下してしまため、種々の提案がなされている。 WC-based cemented carbide is used as a cutting tool because it is excellent in mechanical strength, thermal fatigue resistance, and the like. Cemented carbides generally used for machining high-hardness steels are WC-based cemented carbides, in which grain growth inhibitors such as V, Cr, and Ta are added to reduce the WC average grain size and improve wear resistance. applied. On the other hand, if the grain growth inhibitor is added in a large amount, the toughness is lowered, so various proposals have been made.
例えば、特許文献１には、Ｃｒ、Ｖ、Ｔａの各金属の添加割合を制御して、ＷＣ粒子を小さくし高い靭性を有するＷＣ基超硬合金が記載されている。 For example, Patent Literature 1 describes a WC-based cemented carbide having small WC grains and high toughness by controlling the addition ratio of each metal of Cr, V, and Ta.
本発明者の検討によれば、前記特許文献１に記載されたＷＣ基超硬合金を含む従来のＷＣ基超硬合金を用いた切削工具（ＷＣ基超硬合金の表面に表面被覆層を有する切削工具）では、高硬度鋼の切削加工において、耐摩耗性が十分でない場合があることを認識した。 According to the study of the present inventor, cutting tools using conventional WC-based cemented carbides including the WC-based cemented carbide described in Patent Document 1 (having a surface coating layer on the surface of the WC-based cemented carbide cutting tool), it was recognized that wear resistance may not be sufficient in cutting high-hardness steel.
本発明は、高硬度鋼の切削加工に用いても、耐摩耗性が優れ、耐久性を有する切削工具を与える超硬合金を提供することを目的とする。 SUMMARY OF THE INVENTION An object of the present invention is to provide a cemented carbide which provides a cutting tool having excellent wear resistance and durability even when used for cutting high-hardness steel.
本発明実施形態に係る超硬合金は、
硬質相と結合相を有し、
Ｃｏ：３．０～６．０質量％、Ｖ：０．０２４～０．１８０質量％、Ｃｒ：０．１５０～１．２００質量％、Ｔａ：０．０３０～０．１２０質量％を含み、残部がＷＣと不可避不純物であって、
質量比で、それぞれ、Ｖ／Ｃｏ：０．８～３．０％、Ｃｒ／Ｃｏ：５．０～２０．０％、Ｔａ／Ｃｏ：１．０～２．０％であり、
前記硬質相を構成するＷＣの（０００１）面と前記結合相との界面において、Ｔａが２原子％以下であり、
ビッカース硬度（Ｈｖ３０）が２０００以上である。
The cemented carbide according to the embodiment of the present invention is
having a hard phase and a binder phase,
Co: 3.0 to 6.0% by mass, V: 0.024 to 0.180% by mass, Cr: 0.150 to 1.200% by mass, Ta: 0.030 to 0.120% by mass, The balance being WC and inevitable impurities,
The mass ratios are V/Co: 0.8 to 3.0%, Cr/Co: 5.0 to 20.0%, Ta/Co: 1.0 to 2.0%, respectively,
At the interface between the (0001) plane of WC constituting the hard phase and the binder phase, Ta is 2 atomic% or less,
Vickers hardness (Hv30) is 2000 or more.
また、本実施形態に係る切削工具は、前記超硬合金に硬質皮膜を成膜したものである。 Moreover, the cutting tool according to the present embodiment is obtained by forming a hard coating on the cemented carbide.
前記によれば、切削工具として用いたときに耐摩耗性に優れるＷＣ基超硬合金を得ることができる。 According to the above, it is possible to obtain a WC-based cemented carbide having excellent wear resistance when used as a cutting tool.
本発明者は、結合相を形成するＣｏと、ＷＣ粒の成長抑制剤としてＣｒ、Ｖ、Ｔａの各金属を含むＷＣ基超硬合金において、耐摩耗性を向上させるべく鋭意検討を行った。その結果、Ｃｏの含有割合を小さくし、ＶとＴａの濃化相を粗大化させなければ、ＷＣ基超硬合金の耐摩耗性が向上することを知見した。 The present inventors have made intensive studies to improve the wear resistance of a WC-based cemented carbide containing Co forming a binder phase and Cr, V, and Ta as WC grain growth inhibitors. As a result, the inventors have found that the wear resistance of the WC-based cemented carbide is improved by reducing the content of Co and preventing the V and Ta concentrated phases from coarsening.
以下では、本発明の実施形態について、詳細に説明する。
なお、本明細書および特許請求の範囲において、数値範囲を「Ｌ～Ｍ」（Ｌ、Ｍは共に数値）で表現するときは、その範囲は上限値（Ｍ）および下限値（Ｌ）を含んでおり、上限値（Ｍ）と下限値（Ｌ）の単位は同じである。
Embodiments of the present invention are described in detail below.
In the present specification and claims, when a numerical range is expressed as "L to M" (L and M are both numerical values), the range includes an upper limit (M) and a lower limit (L). , and the units of the upper limit (M) and the lower limit (L) are the same.
１．組成
ＷＣ基超硬合金に含まれる金属元素について説明する。
1. Composition Metal elements contained in the WC-based cemented carbide will be described.
（１）Ｃｏ
Ｃｏは、硬質相をもっぱら構成するＷＣ粒子を繋ぎとめる結合相の主成分であり、ＷＣ基超硬合金に高い靭性を付与する金属元素である。
(1) Co
Co is a major component of a binder phase that binds together WC grains that exclusively constitute the hard phase, and is a metal element that imparts high toughness to the WC-based cemented carbide.
Ｃｏの含有割合が必要以上に少なくなると、脱炭相や遊離炭素が析出しない健全組織を得ることが容易ではなるため、量産に当たり、炭素含有量を適正とすることが難しくなる。さらには、ＷＣ基超硬合金の靭性と強度が低下するため、高硬度鋼のミーリング加工において早期にチッピングが発生する。また、ＷＣ基超硬合金の焼結性が悪化するため、空隙やＣｏプールが発生し易くなり、靭性と強度を高いレベルで維持することが困難になる。 If the Co content is less than necessary, it becomes difficult to obtain a sound structure in which no decarburized phase or free carbon precipitates, making it difficult to optimize the carbon content in mass production. Furthermore, since the toughness and strength of the WC-based cemented carbide are reduced, early chipping occurs during milling of high-hardness steel. In addition, since the sinterability of the WC-based cemented carbide deteriorates, voids and Co pools are likely to occur, making it difficult to maintain high levels of toughness and strength.
一方、Ｃｏの含有割合が必要以上に多くなると、硬度が低下し、また、組織中のＷＣの表面積が小さくなるため、ＷＣ粒子の表面に析出し易いＶの濃化相が粗大に析出し易くなる。 On the other hand, if the content of Co is more than necessary, the hardness decreases and the surface area of WC in the structure decreases, so that the V-enriched phase, which tends to precipitate on the surface of WC particles, tends to precipitate coarsely. Become.
以上を踏まえて、本実施形態のＷＣ基超硬合金は、結合相の主成分であるＣｏを３．０～６．０質量％で含有することが好ましい。Ｃｏの含有比率がこの範囲にあることで、ＷＣ基超硬合金の靭性と強度が高いレベルで両立されるとともに、Ｖの濃化相が粗大化し難くなる。
Ｃｏの含有割合は３．５～５．０質量とすることがより好ましく、３．０～４．５質量％とすることがより一層好ましい。
Based on the above, the WC-based cemented carbide of the present embodiment preferably contains 3.0 to 6.0% by mass of Co, which is the main component of the binder phase. When the content of Co is within this range, the toughness and strength of the WC-based cemented carbide are compatible at high levels, and the V-enriched phase is less likely to coarsen.
The Co content is more preferably 3.5 to 5.0 mass %, and even more preferably 3.0 to 4.5 mass %.
（２）Ｖ
Ｖは、ＷＣの粒成長抑制効果が最も強い元素であり、ＷＣ基超硬合金の組織を微細化するには必要不可欠な元素であって、本実施形態の超硬合金では、０．０２～０．１８質量％含有することが好ましい。
また、本発明者の知見によれば、Ｃｏの含有割合に対するＶの含有割合の質量比、Ｖ／Ｃｏには、適正な範囲が存在することが判明した。
(2) V.
V is an element that has the strongest effect of suppressing grain growth of WC, and is an essential element for refining the structure of the WC-based cemented carbide. It is preferable to contain 0.18% by mass.
Further, according to the findings of the present inventors, it has been found that there is an appropriate range for the mass ratio of the V content to the Co content, V/Co.
Ｖ／Ｃｏがこの適正な範囲よりも小さくなると、ＷＣ基超硬合金のＷＣ平均粒径が粗大となるため、硬度が低下し耐摩耗性が低下してしまう。一方、Ｖ／Ｃｏが適正範囲よりも大きくなると、粗大なＶの濃化相が析出し、ＷＣ基超硬合金の焼結性が悪化し、空隙やＣｏプールが発生し易くなる。たとえば、この適正な範囲よりも大きなＷＣ基超硬合金を用いた切削工具を、高硬度鋼のミーリング加工に供したとき、脆弱なＶの濃化相が粗大に析出すると切削工具損傷が大きくなる。 If the V/Co ratio is less than this appropriate range, the WC-based cemented carbide will have a coarse WC average grain size, resulting in a decrease in hardness and wear resistance. On the other hand, if the V/Co ratio exceeds the appropriate range, a coarse V-enriched phase precipitates, the sinterability of the WC-based cemented carbide deteriorates, and voids and Co pools are likely to occur. For example, when a cutting tool using a WC-based cemented carbide having a size larger than this appropriate range is subjected to milling of high-hardness steel, if the brittle V-enriched phase precipitates coarsely, the cutting tool damage increases. .
以上を踏まえて、本実施形態のＷＣ基超硬合金では、質量比率でＶ／Ｃｏを０．８～３．０％とする。Ｖ／Ｃｏがこの範囲にあることで、ＷＣ基超硬合金の組織が微細となって硬度が高まるとともに、Ｖの濃化相が粗大に析出し難く、本実施形態の超硬合金を使った切削工具では、高硬度鋼のミーリング加工において工具損傷を抑制され易くなる。Ｖ／Ｃｏの適正範囲として１．０～２．５％がより好ましい。 Based on the above, in the WC-based cemented carbide of the present embodiment, the mass ratio of V/Co is set to 0.8 to 3.0%. When V/Co is in this range, the structure of the WC-based cemented carbide is fine and the hardness is increased, and the V-enriched phase is less likely to precipitate coarsely. In the case of cutting tools, tool damage is easily suppressed during milling of high-hardness steel. A more preferable range of V/Co is 1.0 to 2.5%.
（３）Ｃｒ
Ｃｒは、粒成長抑制材であり、Ｖとともに添加することで、ＷＣ基超硬合金の組織を微細化する元素であって、本実施形態の超硬合金では、０．１５～１．２０質量％含有することが好ましい。
また、本発明者の知見によれば、Ｃｒの含有割合に対するＣｏの含有割合の質量比、Ｃｒ／Ｃｏにも、適正な範囲が存在することが判明した。
(3) Cr
Cr is a grain growth inhibitor, and is an element that refines the structure of the WC-based cemented carbide by adding it together with V. In the cemented carbide of the present embodiment, 0.15 to 1.20 mass % is preferable.
Further, according to the findings of the present inventors, it has been found that there is an appropriate range for the mass ratio of the Co content to the Cr content, that is, Cr/Co.
Ｃｒ／Ｃｏの適正範囲は、５．０～２０．０％であることが好ましい。Ｃｒ／Ｃｏがこの範囲にあることで、組織が微細となって超硬合金の硬度が高まるとともに、Ｃｒの濃化相が粗大に析出し難く、本実施形態の超硬合金を使った切削工具では、高硬度鋼のミーリング加工において工具損傷を抑制され易くなる。 The proper range of Cr/Co is preferably 5.0 to 20.0%. When Cr/Co is in this range, the structure becomes finer and the hardness of the cemented carbide increases, and the Cr-enriched phase is less likely to precipitate coarsely, and the cutting tool using the cemented carbide of the present embodiment Therefore, tool damage can be easily suppressed in milling of high-hardness steel.
言い換えると、前記適正範囲よりも小さくなると、ＷＣ基超硬合金の組織が粗大となり、この超硬合金を使った切削工具では耐摩耗性が低下する。一方、前記適正範囲よりも大きくなると、Ｃｒの濃化相が粗大に析出する。また、ＷＣ基超硬合金の焼結性が悪化するため、空隙やＣｏプールが発生し易くなる。
前記適正範囲は、８．０～２０．０％がより好ましい。
In other words, if it is smaller than the appropriate range, the structure of the WC-based cemented carbide becomes coarse, and the wear resistance of the cutting tool using this cemented carbide decreases. On the other hand, if it exceeds the appropriate range, the Cr-enriched phase is coarsely precipitated. Moreover, since the sinterability of the WC-based cemented carbide deteriorates, voids and Co pools are likely to occur.
More preferably, the proper range is 8.0 to 20.0%.
（４）Ｔａ
Ｔａは、粒成長抑制材であり、ＶとＣｒとともに添加することにより、ＷＣ基超硬合金の組織を微細化する。本実施形態の超硬合金では、０．０３～０．１２質量％含有することが好ましい。
また、本発明者の知見によれば、Ｔａの含有割合に対するＣｏの含有割合の質量比、Ｔａ／Ｃｏにも、適正な範囲が存在することが判明した。
(4) Ta
Ta is a grain growth inhibitor, and by adding it together with V and Cr, it refines the structure of the WC-based cemented carbide. The cemented carbide of the present embodiment preferably contains 0.03 to 0.12% by mass.
Further, according to the findings of the present inventors, it has been found that there is an appropriate range for the mass ratio of the Co content to the Ta content, Ta/Co.
Ｔａ／Ｃｏの適正範囲は、１．０～２．０％であることが好ましい。Ｔａ／Ｃｏがこの範囲にあることで、超硬合金の組織が微細となって硬度が高まるとともに、Ｔａの濃化相が粗大に析出し難く、本実施形態の超硬合金を使った切削工具では、高硬度鋼のミーリング加工において工具損傷を抑制され易くなる。
前記適正範囲は、１．０～１．５％がより好ましい。
The proper range of Ta/Co is preferably 1.0 to 2.0%. When Ta/Co is in this range, the structure of the cemented carbide is fine and the hardness is increased, and the Ta-enriched phase is difficult to precipitate coarsely, and the cutting tool using the cemented carbide of the present embodiment Therefore, tool damage can be easily suppressed in milling of high-hardness steel.
More preferably, the appropriate range is 1.0 to 1.5%.
２．硬質相と結合相の界面におけるＴａ含有割合
本実施形態のＷＣ基超硬合金では、硬質相を構成するＷＣ粒子の（０００１）が結合相との界面においてＴａが２原子％以下であることが好ましい。その理由は、同界面のＴａが少ないことで硬質相と結合相の界面強度を高めることができるからである。
2. Ta content ratio at interface between hard phase and binder phase In the WC-based cemented carbide of the present embodiment, the (0001) of the WC grains constituting the hard phase has a Ta content of 2 atomic% or less at the interface with the binder phase. preferable. The reason is that the interfacial strength between the hard phase and the binder phase can be increased by reducing the amount of Ta at the interface.
また、硬質相のＷＣ（０００１）面と結合相との界面では、Ｖの原子％＞Ｃｒの原子％＞Ｔａの原子％であることが好ましい。前記面と結合相との界面では、Ｖは１０．０原子％以下であることが好ましい。なお、「＞」は、不等号である。 Further, at the interface between the WC (0001) plane of the hard phase and the binder phase, it is preferable that the atomic % of V>the atomic % of Cr>the atomic % of Ta. At the interface between the surface and the binder phase, V is preferably 10.0 atomic % or less. ">" is an inequality sign.
３．ビッカース硬度
本実施形態のＷＣ基超硬合金は、ビッカース硬度が２０００以上であることが好ましい。
高硬度鋼をミーリング加工するには、基材であるＷＣ基超硬合金の硬度も高い方がよい。そのため、本実施形態のＷＣ基超硬合金では、ビッカース硬度を２０００以上とする。更にはＷＣ基超硬合金の硬度を２１００以上とすることがより好ましい。ＷＣ基超硬合金の硬度と靭性は二律背反（トレードオフ）の関係にあり、硬度が増加すると靭性が低下する傾向にあり、硬度が低下すると靭性が増加する傾向にある。硬度が高すぎると靭性が低下するため、本実施形態のＷＣ基超硬合金の硬度は２５００以下にすることが好ましい。
3. Vickers Hardness The WC-based cemented carbide of the present embodiment preferably has a Vickers hardness of 2000 or more.
For milling high-hardness steel, it is preferable that the hardness of the WC-based cemented carbide used as the base material is high. Therefore, the WC-based cemented carbide of the present embodiment has a Vickers hardness of 2000 or more. Furthermore, it is more preferable to set the hardness of the WC-based cemented carbide to 2100 or more. The hardness and toughness of the WC-based cemented carbide are in a trade-off relationship, and the toughness tends to decrease as the hardness increases, and the toughness tends to increase as the hardness decreases. If the hardness is too high, the toughness is lowered, so the hardness of the WC-based cemented carbide of the present embodiment is preferably 2500 or less.
ＷＣ基超硬合金の硬度はＣｏ含有比率とＷＣ平均結晶粒径に依存する。本実施形態のＷＣ基超硬合金のＣｏの含有割合でビッカース硬度２０００以上を達成するためには、ＷＣ粒子の円相当の平均結晶粒径は０．６μｍ以下であることがより好ましい。更には、ＷＣ粒子の円相当の平均結晶粒径は０．４μｍ以下であることがより一層好ましい。 The hardness of the WC-based cemented carbide depends on the Co content ratio and the WC average grain size. In order to achieve a Vickers hardness of 2000 or more at the Co content ratio of the WC-based cemented carbide of the present embodiment, the average circle-equivalent crystal grain size of the WC grains is more preferably 0.6 μm or less. Furthermore, the average circle-equivalent crystal grain size of the WC grains is more preferably 0.4 μm or less.
１．ＷＣ基超硬合金の作製
ＷＣ原料粉末は、平均粒径が０．４μｍの粉末を用いた。一方、Ｃｏ原料粉末は、平均粒径が１．５μｍの粉末を、ＶＣ原料粉末は、平均粒径が１μｍの粉末を、Ｃｒ３Ｃ２原料粉末は、平均粒径が１μｍの粉末を、ＴａＣ原料粉末は、平均粒径が１μｍの粉末を、それぞれ、用いた。
1. Production of WC-Based Cemented Carbide Powder having an average particle size of 0.4 μm was used as the WC raw material powder. On the other hand, the Co raw material powder has an average particle size of 1.5 μm, the VC raw material powder has an average particle size of 1 μm, the Cr 3 C 2 raw material powder has an average particle size of 1 μm, and the TaC raw material powder has an average particle size of 1 μm. Powders having an average particle size of 1 μm were used as raw material powders.
これらの原料粉末を所定の組成になるように秤量して、アトライターで湿式混合した。混合の際には、焼結過程で消費される炭素を補うためのＣ粉末と成型用バインダー粉末を微量添加した。混合後、スプレードライヤーで乾燥し各組成の造粒粉を作製して、丸棒を形成した。その後、実施例１～７は１４５０℃の焼結温度で、比較例１は１４３０℃の焼結温度で、それぞれ、１時間保持後、圧力５ＭＰａで焼結して、脱炭相と遊離炭素が析出していない中炭素合金のＷＣ基超硬合金製の丸棒を形成した。 These raw material powders were weighed so as to have a predetermined composition and wet-mixed with an attritor. At the time of mixing, a small amount of C powder and molding binder powder were added to compensate for the carbon consumed during the sintering process. After mixing, the mixture was dried with a spray drier to prepare granulated powder of each composition, and a round bar was formed. After that, Examples 1 to 7 were sintered at a sintering temperature of 1450° C., and Comparative Example 1 was at a sintering temperature of 1430° C. After being held for 1 hour, they were sintered at a pressure of 5 MPa to form a decarburized phase and free carbon. A round bar made of unprecipitated medium carbon alloy WC-based cemented carbide was formed.
その後、これらの丸棒を切削評価用としてボールエンドミル形状に加工した。また、物性評価用に丸棒を加工して硬度測定と組織観察を行った。表１に組成と硬度の測定結果を示す。組織観察では、鏡面研磨した焼結体の断面をフィールドエミッション電子プローブマイクロアナライザ（ＥＰＭＡ、日本電子製ＪＸＡ－８５３０Ｆ型）を用いて１５００倍でＶの面分析を行った。面分析において、Ｖが２質量％以上／ピクセルで測定された場合、粗大なＶ濃化相ありと判断した。その結果、ＣｏとＶが多い比較例１の基材のみ粗大なＶ濃化相が確認された。 After that, these round bars were processed into a ball end mill shape for cutting evaluation. In addition, a round bar was processed for physical property evaluation, and hardness measurement and structure observation were performed. Table 1 shows the composition and hardness measurement results. In the structure observation, the cross section of the mirror-polished sintered body was subjected to V surface analysis at 1500 times using a field emission electron probe microanalyzer (EPMA, JXA-8530F manufactured by JEOL Ltd.). In area analysis, if V was measured at 2% by weight or more/pixel, it was determined that there was a coarse V-enriched phase. As a result, a coarse V-enriched phase was confirmed only in the substrate of Comparative Example 1, which contained a large amount of Co and V.
ビッカース硬度は、基材を鏡面研磨して、ビッカース硬さ試験機（明石製作所製ＡＶＫ型）を用いて試験力ＨＶ３０（２９４．２Ｎ）、保持時間１５秒の条件で２点測定し、その平均値から求めた。 The Vickers hardness is obtained by mirror-polishing the base material and using a Vickers hardness tester (AVK type manufactured by Akashi Seisakusho Co., Ltd.) under the conditions of a test force of HV30 (294.2 N) and a holding time of 15 seconds. calculated from the value.
２．硬質皮膜の成膜
硬質皮膜の成膜には、アークイオンプレーティング方式の成膜装置を用いた。基材の表面に約２μｍのＡｌＣｒＳｉＮを被覆した後に約１μｍのＴｉＳｉＮを被覆し、実施例１～７と比較例１の切削工具を得た。
2. Formation of Hard Coating An arc ion plating type coating apparatus was used for forming the hard coating. The surface of the substrate was coated with about 2 μm of AlCrSiN and then with about 1 μm of TiSiN to obtain cutting tools of Examples 1 to 7 and Comparative Example 1.
３．切削試験
実施例、比較例に対して、以下の切削試験１～３を行い、切削試験後の基材露出面積から被覆切削工具の耐摩耗性を評価した。切削試験１～３の各試験条件を以下に示す。
切削試験１～３共に、評価方法である基材露出面積率は、切削加工後、走査型電子顕微鏡を用いて所定の倍率で観察し、基材の超硬合金が露出した部分が全体に占める割合を算出した。基材露出面積率の算出には市販の画像解析ソフトを用いた。
3. Cutting Test The following cutting tests 1 to 3 were performed for Examples and Comparative Examples, and the wear resistance of the coated cutting tool was evaluated from the exposed area of the base material after the cutting test. The test conditions for cutting tests 1 to 3 are shown below.
In both cutting tests 1 to 3, the substrate exposed area ratio, which is an evaluation method, was observed at a predetermined magnification using a scanning electron microscope after cutting, and the portion where the cemented carbide of the substrate was exposed accounted for the whole. A percentage was calculated. Commercially available image analysis software was used to calculate the substrate exposed area ratio.
（１）切削試験１の切削条件
・工具：２枚刃超硬ボールエンドミル（ボール半径０．３ｍｍ）
・切削方法：ポケット加工（２５ｍｍ×２５ｍｍ×深さ０．０８ｍｍ）
・被削材：ＡＳＰ２３（６４ＨＲＣ）
・切り込み：軸方向、０．０４ｍｍ、径方向、０．１２ｍｍ
・切削速度：７５ｍ／ｍｉｎ
・一刃送り量：０．０１５ｍｍ／刃
・切削油：ミストブロー（油性）
・加工個数：４ポケット
・基材露出面積率の観察倍率：３００倍
基材露出面積率（＝基材露出部の面積／基材の全面積×１００）の結果を表２に示す。
(1) Cutting conditions for cutting test 1 Tool: 2-flute carbide ball end mill (ball radius 0.3 mm)
・Cutting method: pocketing (25mm x 25mm x depth 0.08mm)
・Work material: ASP23 (64HRC)
・Incision: 0.04 mm in the axial direction, 0.12 mm in the radial direction
・Cutting speed: 75m/min
・One blade feed rate: 0.015mm/blade ・Cutting oil: Mist blow (oil-based)
-Number of pockets to be processed: 4 -Observation magnification of base material exposed area ratio: 300 times Table 2 shows the results of the base material exposed area ratio (=area of base material exposed portion/total area of base material x 100).
（２）切削試験２の切削条件
・工具：２枚刃超硬ボールエンドミル（ボール半径０．１５ｍｍ）
・切削方法：ポケット加工（１ｍｍ×３ｍｍ×深さ０．４ｍｍ）
・被削材：ＡＳＰ２３（６４ＨＲＣ）
・切り込み：軸方向、０．０１３ｍｍ、径方向、０．０１３ｍｍ
・切削速度：３７．７ｍ／ｍｉｎ
・一刃送り量：０．００４５ｍｍ／刃
・切削油：ミストブロー（油性）
・加工個数：２０ポケット
・基材露出面積率の観察倍率：６００倍
基材露出面積率の結果を表３に示す。
(2) Cutting conditions for cutting
・Cutting method: pocket processing (1mm x 3mm x depth 0.4mm)
・Work material: ASP23 (64HRC)
・Incision: 0.013 mm in axial direction, 0.013 mm in radial direction
・Cutting speed: 37.7m/min
・One blade feed amount: 0.0045mm/blade ・Cutting oil: Mist blow (oil-based)
-Number of pockets processed: 20 -Observation magnification of base material exposed area ratio: 600 times Table 3 shows the results of the base material exposed area ratio.
（３）切削試験３の切削条件
・工具：２枚刃超硬ボールエンドミル（ボール半径０．１５ｍｍ）
・切削方法：ポケット加工（１ｍｍ×３ｍｍ×深さ０．４ｍｍ）
・被削材：ＡＳＰ２３（６４ＨＲＣ）
・切り込み：軸方向、０．００６ｍｍ、径方向、０．００６ｍｍ
・切削速度：３７．７ｍ／ｍｉｎ
・一刃送り量：０．００４５ｍｍ／刃
・切削油：ミストブロー（油性）
・加工個数：７ポケット
・基材露出面積率の観察倍率：６００倍
基材露出面積率の結果を表４に示す。
(3) Cutting conditions for cutting test 3 Tool: 2-flute carbide ball end mill (ball radius 0.15 mm)
・Cutting method: pocket processing (1mm x 3mm x depth 0.4mm)
・Work material: ASP23 (64HRC)
・Incision: axial direction, 0.006 mm, radial direction, 0.006 mm
・Cutting speed: 37.7m/min
・One blade feed amount: 0.0045mm/blade ・Cutting oil: Mist blow (oil-based)
-Number of pockets processed: 7 -Observation magnification of base material exposed area ratio: 600 times Table 4 shows the results of the base material exposed area ratio.
表２～４から明らかなように、実施例は何れの加工においても基材露出面積率が小さく、高硬度鋼の切削加工において、優れた耐久性を示した。この理由としては、実施例は低Ｃｏで高硬度を維持した上で粒成長抑制材の粗大な濃化相がないためと考えられる。 As is clear from Tables 2 to 4, the examples showed a small base material exposed area ratio in any processing, and exhibited excellent durability in cutting high-hardness steel. The reason for this is thought to be that the examples maintain high hardness with a low Co content and do not have coarse concentrated phases of the grain growth inhibitor.
ここで、図１は、実施例１を組織観察した写真であり、この写真内の硬質相（図２ではＷＣ相と示す）ＷＣ（０００１）面と記載した面と結合相（図２ではＣｏ相と示す）の界面におけるＴａの分布を測定した。その結果を図２に示すが、前記界面でＴａが少ないことから界面強度が高まっているため、優れた耐久性を示したと推定される。 Here, FIG. 1 is a photograph obtained by observing the structure of Example 1. In this photograph, the hard phase (indicated as WC phase in FIG. 2) and the surface described as WC (0001) plane and the binder phase (Co The distribution of Ta at the interface between the phases) was measured. The results are shown in FIG. 2. It is presumed that the excellent durability was exhibited because the interface strength was increased due to the small amount of Ta at the interface.
Claims (2)
Ｃｏ：３．０～６．０質量％、Ｖ：０．０２４～０．１８０質量％、Ｃｒ：０．１５０～１．２００質量％、Ｔａ：０．０３０～０．１２０質量％を含み、残部がＷＣと不可避不純物であって、
質量比で、それぞれ、Ｖ／Ｃｏ：０．８～３．０％、Ｃｒ／Ｃｏ：５．０～２０．０％、Ｔａ／Ｃｏ：１．０～２．０％であり、
前記硬質相を構成するＷＣの（０００１）面と前記結合相との界面において、Ｔａが２原子％以下であり、
ビッカース硬度（Ｈｖ３０）が２０００以上である、
ことを特徴とする超硬合金。 having a hard phase and a binder phase,
Co: 3.0 to 6.0% by mass, V: 0.024 to 0.180% by mass, Cr: 0.150 to 1.200% by mass, Ta: 0.030 to 0.120% by mass, The balance being WC and inevitable impurities,
The mass ratios are V/Co: 0.8 to 3.0%, Cr/Co: 5.0 to 20.0%, Ta/Co: 1.0 to 2.0%, respectively,
At the interface between the (0001) plane of WC constituting the hard phase and the binder phase, Ta is 2 atomic% or less,
Vickers hardness (Hv30) is 2000 or more,
A cemented carbide characterized by:
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