JP6516440B2 - Powdered high speed tool steel - Google Patents
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- JP6516440B2 JP6516440B2 JP2014222003A JP2014222003A JP6516440B2 JP 6516440 B2 JP6516440 B2 JP 6516440B2 JP 2014222003 A JP2014222003 A JP 2014222003A JP 2014222003 A JP2014222003 A JP 2014222003A JP 6516440 B2 JP6516440 B2 JP 6516440B2
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- 229910001315 Tool steel Inorganic materials 0.000 title claims description 30
- 239000000843 powder Substances 0.000 claims description 95
- 150000001247 metal acetylides Chemical class 0.000 claims description 46
- 229910000831 Steel Inorganic materials 0.000 claims description 23
- 239000010959 steel Substances 0.000 claims description 23
- 239000002184 metal Substances 0.000 claims description 20
- 229910052751 metal Inorganic materials 0.000 claims description 20
- 238000002156 mixing Methods 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 10
- 229910052721 tungsten Inorganic materials 0.000 claims description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims description 7
- 229910052804 chromium Inorganic materials 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 229910052720 vanadium Inorganic materials 0.000 claims description 5
- 229910000997 High-speed steel Inorganic materials 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 description 25
- 239000002245 particle Substances 0.000 description 24
- 230000000052 comparative effect Effects 0.000 description 20
- 239000000463 material Substances 0.000 description 19
- 239000010953 base metal Substances 0.000 description 18
- 230000000694 effects Effects 0.000 description 11
- 238000000034 method Methods 0.000 description 9
- 238000007711 solidification Methods 0.000 description 8
- 230000008023 solidification Effects 0.000 description 8
- 239000011159 matrix material Substances 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 7
- 238000005520 cutting process Methods 0.000 description 6
- 238000001513 hot isostatic pressing Methods 0.000 description 5
- 238000005299 abrasion Methods 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000011812 mixed powder Substances 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 238000007493 shaping process Methods 0.000 description 3
- 238000005496 tempering Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000009689 gas atomisation Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 238000004663 powder metallurgy Methods 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 238000009740 moulding (composite fabrication) Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- OXNIZHLAWKMVMX-UHFFFAOYSA-N picric acid Chemical compound OC1=C([N+]([O-])=O)C=C([N+]([O-])=O)C=C1[N+]([O-])=O OXNIZHLAWKMVMX-UHFFFAOYSA-N 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Description
本発明は、切削工具や金型等に使用される粉末高速度工具鋼に関する。 The present invention relates to a powder high-speed tool steel used for cutting tools, dies and the like.
従来、高速度工具鋼はＣ、Ｃｒ、Ｗ、Ｍｏ、Ｖ、Ｃｏ等の合金元素を多量に加えて高温で硬さや耐摩耗性を一層高めた工具鋼であり、エンドミルやドリルのように比較的靱性が要求される切削工具の素材として汎用されている。ところで、このような高速度工具鋼は、従来では溶製法によって製造されていたのであるが、この溶製法によって得られた高速度工具鋼では、粗大炭化物の存在や偏析という問題があったことから、近年では、従来の溶製法に代わって、粉末冶金法を用いた粉末高速度工具鋼が広く使用されるようになっている。この粉末高速度工具鋼は、高速度工具鋼の溶湯をアトマイズ法によって急冷凝固粉末とし、この粉末を熱間静水圧加圧（ＨＩＰ）等の粉末冶金法によって製造される。 In the past, high-speed tool steels are tool steels that have added a large amount of alloying elements such as C, Cr, W, Mo, V, Co, etc. to further enhance hardness and wear resistance at high temperatures, and compare them like end mills and drills. It is widely used as a material for cutting tools that require high toughness. By the way, such high-speed tool steel was conventionally manufactured by a melting method, but the high-speed tool steel obtained by this melting method had problems such as presence or segregation of coarse carbides. In recent years, powder high-speed tool steel using powder metallurgy has come into widespread use in place of conventional melting processes. The powder high-speed tool steel is manufactured by converting the molten metal of high-speed tool steel into a rapidly solidified powder by the atomizing method, and this powder by the powder metallurgy method such as hot isostatic pressing (HIP).
一方、上記のような粉末高速度工具鋼を切削工具の素材として実際使用した場合には、耐摩耗性および靱性が不十分なことから、工具の切削性能の向上という要求に十分対応できない。このようなことから、耐摩耗性および靱性をより高めて工具の切削性能をより向上させるという観点で、これまでにも様々な粉末高速度工具鋼について提案されている。
例えば、特許文献１に開示されているように、質量％で、Ｃ：１．２〜３％、Ｓｉ：３．０％以下、Ｍｎ：３．０％以下、Ｃｒ：３〜６％、Ｗ：１０〜１５％、Ｍｏ：１．０％以下、Ｖ：３〜５％、Ｃｏ：１０％以下を含有する高速度工具鋼用粉末が提案されている。
On the other hand, when the powder high-speed tool steel as described above is actually used as a material of a cutting tool, the wear resistance and the toughness are insufficient, and the requirement for improvement of the cutting performance of the tool can not be sufficiently addressed. For these reasons, various powder high-speed tool steels have been proposed in view of further enhancing wear resistance and toughness to further improve the cutting performance of the tool.
For example, as disclosed in Patent Document 1, C: 1.2 to 3%, Si: 3.0% or less, Mn: 3.0% or less, Cr: 3 to 6%, W by mass. Powders for high-speed tool steels have been proposed which contain 10 to 15%, Mo: 1.0% or less, V: 3 to 5%, Co: 10% or less.
特許文献２は、重量比で、Ｃ：０．７〜２．０％、Ｓｉ：≦１．０％、Ｍｎ：≦０．６％、Ｃｒ：３．０〜６．０％、ＷまたはさらにＭｏをＷ＋２Ｍｏで１４〜２０％かつＶ：≦５．０％、Ｎｂ：２．０〜７．０％、但しＮｂ／Ｖ≧０．５、残部がＦｅおよび不可避的不純物よりなる粉末高速度工具鋼が提案されている。 Patent Document 2 is C: 0.7 to 2.0%, Si: ≦ 1.0%, Mn: ≦ 0.6%, Cr: 3.0 to 6.0%, W or more in weight ratio Powdered high-speed tool consisting of 14 to 20% Mo and W: 2Mo and V:% 5.0%, Nb: 2.0 to 7.0%, except that Nb / V 0.5 0.5, the balance being Fe and unavoidable impurities Steel has been proposed.
また、特許文献３に開示されているように、ＮｉおよびＣｏを含むＭｏ系高速度工具鋼であって、Ｎｂを０．５〜２．０％含有すると共に、炭化物の平均粒径が０．４０〜０．８０μｍであり、かつ最大粒径が５μｍ以下である耐摩耗性および耐チッピング性に優れた粉末高速度工具鋼が提案されている。 Further, as disclosed in Patent Document 3, a Mo-based high-speed tool steel containing Ni and Co, containing 0.5 to 2.0% of Nb, and having an average grain diameter of carbide of 0. A powder high-speed tool steel excellent in wear resistance and chipping resistance having a maximum particle size of 40 to 0.80 μm and a maximum particle size of 5 μm or less has been proposed.
上述した、特許文献１は成分制御により耐摩耗性、靱性の改善を狙っているが、炭化物サイズが２．０μｍと耐摩耗性に懸念があり十分ではない。特許文献２はＮｂを２．０〜７．０％添加により耐摩耗性、靱性を持たせているが、しかし、Ｖ：≦５．０％、Ｎｂ／Ｖ≧０．５とＶ添加量が少ないために耐摩耗性に劣るという問題がある。さらに、特許文献３はＮｂを０．５〜２．０％添加かつＮｉ、Ｃｏを含む粉末高速度鋼と耐摩耗性、靱性を高めているが、しかしながら、Ｎｂを含む必要があり、そのため成分系に制約があるという問題がある。それらの問題に対し、本発明は、Ｃ濃度が異なる金属粉末を母材にして粉末高速度工具鋼を製造し、熱処理を加えて炭化物を制御することで耐摩耗性と靭性を兼ね備えた粉末高速度工具鋼が得られることを見出し、その粉末高速度工具鋼を提供することにある。 Although Patent Document 1 mentioned above aims to improve wear resistance and toughness by component control, the carbide size is 2.0 μm, which is not sufficient because of the concern about wear resistance. Patent Document 2 gives wear resistance and toughness by adding 2.0 to 7.0% of Nb, but V: 5.0 5.0%, Nb / V 0.5 0.5, and the amount of V added There is a problem that it is inferior in abrasion resistance because it is small. Furthermore, although the patent document 3 adds 0.5 to 2.0% of Nb and improves the wear resistance and toughness with a powder high speed steel containing Ni and Co, however, it is necessary to include Nb, and therefore the components There is a problem that the system is restricted. In response to these problems, the present invention manufactures a powder high-speed tool steel by using metal powders different in C concentration as a base material, applies heat treatment and controls carbides, thereby achieving a powder high having both wear resistance and toughness. It is found that a high speed tool steel can be obtained, and to provide the powder high speed tool steel.
上述の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、粉末高速度工具鋼は、通常は単一粉末を母材に作製するのが一般的であるが、Ｃ濃度が０．５％以上異なる２種類以上の金属粉末を母材に用いて焼結し、さらに熱処理により粗大なＭＣ炭化物と微細なＭ6Ｃ炭化物が混在する組織とすることで、耐摩耗性と靭性を両立できることを見出し、その粉末高速度工具鋼を得ることを見出した。 As a result of the inventors' intensive development to solve the above problems, as a result of powder high-speed tool steel, generally it is common to make a single powder base material, but C concentration By using two or more types of metal powders differing by 0.5% or more as a base material to sinter, and further by heat treatment to form a structure in which coarse MC carbides and fine M 6 C carbides are mixed, abrasion resistance and It has been found that the toughness can be compatible, and it is found that the powder high-speed tool steel can be obtained.
上記の課題を解決する手段としては、第１の手段は、質量％で、Ｃ：１．３０〜２．３０％、Ｓｉ：０．１〜１．０％、Ｍｎ：０．１〜１．０％、Ｃｒ：３．０〜５．０％、Ｍｏ：０．５〜５.０％、Ｗ：５．０〜２０．０％、Ｖ：３．０〜７．５％を含有し、残部Ｆｅおよび不可避的不純物よりなる鋼であり、該鋼中にある炭化物のうち、ＭＣ炭化物の最大径は３．５〜１０μｍを、Ｍ6Ｃ炭化物の最大径は２．５μｍ以下を満たすことを特徴とする粉末高速度工具鋼である。 As means for solving the above problems, the first means is, by mass%, C: 1.30 to 2.30%, Si: 0.1 to 1.0%, Mn: 0.1 to 1. 0%, Cr: 3.0 to 5.0%, Mo: 0.5 to 5.0%, W: 5.0 to 20.0%, V: 3.0 to 7.5%, It is a steel consisting of the balance Fe and unavoidable impurities, and among carbides in the steel, the maximum diameter of MC carbide is 3.5 to 10 μm and the maximum diameter of M 6 C carbide is 2.5 μm or less. It is a powder high-speed tool steel that is characterized.
第２の手段は、上記の第１手段の成分組成に加えて、さらにＣｏ：１０．０％以下（ただし０％は含まない。）を含有し、残部Ｆｅおよび不可避的不純物よりなる鋼であり、該鋼中にある炭化物のうち、ＭＣ炭化物の最大径は３．５〜１０μｍを、Ｍ6Ｃ炭化物の最大径は２．５μｍ以下を満たすことを特徴とする粉末高速度工具鋼である。 The second means is a steel further containing Co: 10.0% or less (but not including 0%) in addition to the component composition of the first means described above, the balance being Fe and unavoidable impurities. Among the carbides in the steel, the maximum diameter of MC carbides is 3.5 to 10 μm, and the maximum diameter of M 6 C carbides is 2.5 μm or less.
第３の手段は、上記の第１手段または第２手段の粉末高速度鋼の成分組成を含有し、残部Ｆｅおよび不可避的不純物よりなる金属粉末のうち、Ｃ濃度が０．５％以上異なる２種類以上の金属粉末を混合し固化成形した鋼であり、該鋼中にある炭化物のうち、ＭＣ炭化物の最大径は３．５〜１０μｍ、Ｍ6Ｃ炭化物の最大径は２．５μｍ以下を満たすことを特徴とする粉末高速度工具鋼である。 The third means contains the component composition of the powder high-speed steel of the first means or the second means described above, and among the metal powders consisting of the balance Fe and unavoidable impurities, the C concentration differs by 0.5% or more 2 It is a steel formed by mixing and solidifying and forming more than types of metal powder, and among carbides in the steel, the maximum diameter of MC carbide is 3.5 to 10 μm, and the maximum diameter of M 6 C carbide is 2.5 μm or less Powder high-speed tool steel characterized by
以上述べたように、本発明により耐摩耗性および靱性を兼ね備えた粉末高速度工具鋼を得ることができる。 As described above, according to the present invention, a powder high-speed tool steel having both wear resistance and toughness can be obtained.
以下、本発明について詳細に説明する。
本発明成分範囲内の粉末高速度工具鋼において、組織内に析出している炭化物は、ＶＣから成るＭＣ炭化物と（Ｆｅ、Ｗ、Ｍｏ）6Ｃを主体とするＭ6Ｃ炭化物の２種類に分類される。これら炭化物のうち、ＭＣ炭化物は高硬度であるため、材料の耐摩耗性を向上させる働きをする。そのため、ＭＣ炭化物を粗大化させることで、耐摩耗性を改善させることが可能であるが、一方で粗大な炭化物は靭性を阻害してしまうため、一部の炭化物は微細な炭化物のままで保持しておくことが必要とされる。また、Ｍ6Ｃ炭化物はＭＣ炭化物ほど耐摩耗性に寄与しないため、Ｍ6Ｃ炭化物は微細なままに保ちつつ、ＭＣ炭化物を粗大化させた組織に制御することで耐摩耗性と靭性を両立させた粉末高速度工具鋼が得られると考えた。
Hereinafter, the present invention will be described in detail.
In the powder high-speed tool steel within the composition range of the present invention, carbides precipitated in the structure are classified into two types, MC carbide composed of VC and M 6 C carbide mainly composed of (Fe, W, Mo) 6 C. being classified. Among these carbides, MC carbide has a high hardness, and thus works to improve the wear resistance of the material. Therefore, it is possible to improve wear resistance by coarsening MC carbides, but on the other hand, since coarse carbides inhibit toughness, some carbides are retained as fine carbides. It is necessary to keep it. In addition, M 6 C carbides do not contribute to wear resistance as MC carbides, so while maintaining M 6 C carbides as fine, both wear resistance and toughness can be achieved by controlling the MC carbides into a coarsened structure. It is thought that a powder high speed tool steel can be obtained.
このような組織を達成するために鋭意開発を進めた結果、粉末高速度工具鋼をＣ（炭素）濃度が０．５％以上異なる２種類以上の金属粉末を母材に用いてＨＩＰまたは押出しにより固化成型後、熱処理を行い、ＭＣ炭化物の最大径が３．５〜１０μｍ、Ｍ6Ｃ炭化物の最大径は２．５μｍ以下を満たすように炭化物径を制御することで靱性と耐摩耗性を兼ね備えた粉末高速度工具鋼が得られることを発見した。 As a result of intensive development to achieve such a structure, powder high-speed tool steel is subjected to HIP or extrusion by using two or more types of metal powders different in C (carbon) concentration by 0.5% or more as a base material After solidification and forming, heat treatment is performed, and by controlling the carbide diameter so that the maximum diameter of MC carbide is 3.5 to 10 μm and the maximum diameter of M 6 C carbide is 2.5 μm or less, it has both toughness and wear resistance. It was found that a powder high speed tool steel was obtained.
粉末高速度工具鋼を作製する際に、Ｃ濃度差が０．５％以上ある高Ｃ粉末と低Ｃ粉末を混合、固化成型して粉末高速度工具鋼を作製すると、マトリックス中のＣ濃度に大きな濃淡が生じる。この状態で、高温保持熱処理を行い、Ｃ拡散を促進させた場合、Ｃ濃度が高い領域の炭化物は優先して粗大化するが、Ｃ濃度が低い領域は、マトリックス中にＣが溶け込んでいないために、炭化物の粗大化が殆ど起こらない。この際に、炭化物の融点の差から優先して粗大化が起こるのはＭＣ炭化物であり、Ｍ6Ｃ炭化物は微細なままで保たれる。結果として、粗大なＭＣ炭化物と微細なＭ6Ｃ炭化物が共に存在する組織となる。 When producing powder high-speed tool steel, if high-C powder and low-C powder with a C concentration difference of 0.5% or more are mixed and solidified to produce powder high-speed tool steel, the C concentration in the matrix is There is a great deal of light and shade. In this state, if high temperature holding heat treatment is performed to promote C diffusion, carbides in a region with high C concentration are preferentially coarsened, but in a region with low C concentration, C is not dissolved in the matrix. There is almost no coarsening of carbides. At this time, it is MC carbide that coarsening occurs preferentially due to the difference in melting point of carbide, and M 6 C carbide is kept fine. As a result, a structure in which coarse MC carbides and fine M 6 C carbides are present together is obtained.
図１は本発明例Ｎｏ．１に示す２種類の混合粉末を母材として固化成型した後に、熱処理によって炭化物径を調整して作製し、この母材である本発明鋼の光学顕微鏡による組織を示す写真である。これに対し、図２は比較例であるＮｏ．４に示す単一粉末を熱処理粒度調整なしで作製した鋼の光学顕微鏡による組織であり、図３は比較例であるＮｏ．５に示す２種類の混合粉末を母材に作製し、熱処理粒度調整なしで作製した鋼の光学顕微鏡による組織であり、図４は比較例であるＮｏ．７に示す単一粉末を熱処理粒度調整して作製した鋼の光学顕微鏡による組織を示す写真である。これから分かるように、図１の本発明は、図２〜４に比較して粗大なＭＣ炭化物と微細なＭ6Ｃ炭化物が混在した組織となり、図２〜４に見られる組織とは異なることが分かる。粉末の製法はガスアトマイズ法が低酸素粉末が得られ好ましいが、水アトマイズ粉末、粉砕粉末等の製法も可である。 FIG. 1 is an example of the present invention. It is a photograph which shows the structure by the optical microscope of the present invention steel which adjusts and manufactures the carbide diameter by heat treatment, after solidifying and forming two kinds of mixed powder shown in 1 as a base material. On the other hand, FIG. Fig. 4 shows the structure of a steel produced by heat treating the single powder shown in Fig. 4 without adjusting the grain size by an optical microscope, and Fig. 3 shows a comparative example No. 4 as a comparative example. FIG. 4 shows the structure of a steel produced by using two types of mixed powder shown in No. 5 as a base material and without heat treatment particle size adjustment, as shown in FIG. It is a photograph which shows the structure by light microscope of steel manufactured by heat-processing particle size adjustment of the single powder shown to 7. As understood from this, the present invention of FIG. 1 has a structure in which coarse MC carbides and fine M 6 C carbides are mixed as compared with FIGS. 2 to 4 and is different from the structure seen in FIGS. I understand. The powder is preferably produced by a gas atomizing method because a low oxygen powder can be obtained, but a method such as a water atomized powder or a pulverized powder may also be used.
以下、本発明の粉末高速工具鋼に係る金属粉末の化学成分の限定理由について説明する。 Hereinafter, the reasons for limitation of the chemical components of the metal powder according to the powder high-speed tool steel of the present invention will be described.
Ｃ：１．３０〜２．３０％
Ｃは、硬さ、焼入性に必要な元素である。しかし、Ｃは１．３０％未満ではその効果が十分でない。また、Ｃが２．３０％を超えると粗大すぎる炭化物を形成し靱性を悪化させることから、Ｃは１．３０〜２．３０％とする。
C: 1.30 to 2.30%
C is an element necessary for hardness and hardenability. However, if C is less than 1.30%, the effect is not sufficient. Further, when C exceeds 2.30%, carbides that are too coarse are formed to deteriorate toughness, so C is made 1.30 to 2.30%.
Ｓｉ：０．１〜１．０％
Ｓｉは、脱酸剤であり、基地の硬さを得るために必要な元素である。しかし、Ｓｉは０．１％未満ではその効果が十分に得られず、１．０％を超えると靱性と加工性が悪化する。そこでＳｉは０．１〜１．０％とする。
Si: 0.1 to 1.0%
Si is a deoxidizer and is an element necessary to obtain the hardness of the matrix. However, if the amount of Si is less than 0.1%, the effect can not be sufficiently obtained, and if it exceeds 1.0%, the toughness and the processability deteriorate. Therefore, the Si content is 0.1% to 1.0%.
Ｍｎ：０．１〜１．０％
Ｍｎは、脱酸剤であり、焼入性を得るために必要な元素である。しかし、Ｍｎは０．１％未満では、その効果が十分に得られず、１．０％を超えるとマトリックスを脆化させ靱性、熱間加工性が悪化する。そこでＭｎは０．１〜１．０％とする。
Mn: 0.1 to 1.0%
Mn is a deoxidizer and is an element necessary to obtain hardenability. However, if Mn is less than 0.1%, the effect is not sufficiently obtained, and if it exceeds 1.0%, the matrix is embrittled to deteriorate the toughness and the hot workability. Therefore, the Mn is 0.1 to 1.0%.
Ｃｒ：３．０〜５．０％
Ｃｒは、焼入性を得るために必要な元素である。しかし、Ｃｒは３．０％未満ではその効果が十分でない。また、５．０％を超えると靱性、熱間加工性が悪化する。そこでＣｒは３．０〜５．０％とする。
Cr: 3.0 to 5.0%
Cr is an element necessary to obtain hardenability. However, if Cr is less than 3.0%, the effect is not sufficient. If it exceeds 5.0%, the toughness and the hot workability deteriorate. Therefore, Cr is set to 3.0 to 5.0%.
Ｍｏ：０．５〜５．０％
Ｍｏは、焼入性、硬さ、耐摩耗性、焼戻し軟化抵抗性を得るために必要な元素である。しかし、Ｍｏは０．５％未満ではその効果が十分でなく、また、５．０％を超えると靱性、熱間加工性が悪化する。そこでＭｏは０．５〜５．０％とする。好ましくはＭｏは０．５〜４．０％とする。
Mo: 0.5 to 5.0%
Mo is an element necessary to obtain hardenability, hardness, wear resistance, and temper softening resistance. However, if Mo is less than 0.5%, the effect is not sufficient, and if it exceeds 5.0%, toughness and hot workability are deteriorated. Therefore, Mo is set to 0.5 to 5.0%. Preferably, Mo is 0.5 to 4.0%.
Ｗ：５．０〜２０．０％
Ｗは、焼入性、硬さ、耐摩耗性、焼戻し軟化抵抗性を得るために必要な元素である。しかし、Ｗは５．０％未満ではその効果が十分でなく、２０．０％を超えると靱性、熱間加工性が悪化する。そこでＷは５．０〜２０．０％とする。好ましくはＷは８．０〜１２．０％とする。
W: 5.0 to 20.0%
W is an element necessary to obtain hardenability, hardness, wear resistance, temper softening resistance. However, if W is less than 5.0%, the effect is not sufficient, and if it exceeds 20.0%, the toughness and the hot workability deteriorate. Therefore, W is set to 5.0 to 20.0%. Preferably, W is set to 8.0 to 12.0%.
Ｖ：３．０〜７．５％
Ｖは、硬さ、耐焼付き性、靱性を得るために必要な元素である。しかし、Ｖは３．０％未満ではその効果が十分でなく、７．５％を超えると靱性、被削性が悪化する。そこでＶは３．０〜７．５％とする。好ましくはＶは４．６〜７．０％とする。
V: 3.0 to 7.5%
V is an element necessary to obtain hardness, seizure resistance, and toughness. However, if V is less than 3.0%, the effect is not sufficient, and if it exceeds 7.5%, toughness and machinability deteriorate. Therefore, V is set to 3.0 to 7.5%. Preferably, V is set to 4.6 to 7.0%.
Ｃｏ：１０．０％以下（ただし、０％は含まない。）
Ｃｏは、耐熱性、耐摩耗性、耐焼戻し軟化抵抗性に必要な元素である。本元素を含まなくても本発明の耐摩耗性および靱性の効果は得られるが、上記の耐熱性、耐摩耗性、耐焼戻し軟化抵抗性の点から含有することが好ましい。しかし、Ｃｏが１０．０％を超える添加は炭化物の偏析や脱炭を促進することから、その上限を１０．０％とした。
Co: 10.0% or less (but excluding 0%)
Co is an element necessary for heat resistance, wear resistance, and resistance to temper softening. Although the effects of wear resistance and toughness of the present invention can be obtained even if the element is not contained, it is preferable to contain from the viewpoints of the above heat resistance, wear resistance and resistance to temper softening. However, the addition of more than 10.0% of Co promotes segregation of carbide and decarburization, so the upper limit is made 10.0%.
本願でいう炭化物の最大径は以下の通りに定義する。
炭化物の形状は真円ではないのでその断面には径の長いところと短いところがある。その径も最も長い径（以下、最長径という。）を取上げて、ある観察面積中に存在する炭化物を観察し、これらの各炭化物の最長径を計測し、その中で最も大きな値を示す炭化物の最長径のことを本願では炭化物の最大径というものとする。
In the present application, the maximum diameter of carbide is defined as follows.
Since the shape of the carbide is not a perfect circle, its cross section has long and short diameters. Taking the longest diameter (hereinafter referred to as the longest diameter), observing the carbides present in a certain observation area, measuring the longest diameter of each of these carbides, the carbide showing the largest value among them In the present application, the longest diameter of is referred to as the maximum diameter of carbide.
上記の炭化物の最大径の定義の下で、焼入、焼戻したミクロ組織の、ＭＣ炭化物の最大径が３．５〜１０μｍと限定した理由は以下の通りである。
ＭＣ炭化物はＭ6Ｃ炭化物よりも硬く、その径が大きいほど耐摩耗性を向上させる。ただし、ＭＣ炭化物の最大径が３．５μｍ未満だと耐摩耗性向上の効果が十分に得られず、１０μｍより大きいと破壊の起点となり靭性を阻害するため、ＭＣ炭化物の最大径の範囲を３．５〜１０μｍとした。
The reasons why the maximum diameter of MC carbide of the quenched and tempered microstructure is limited to 3.5 to 10 μm under the above definition of the maximum diameter of carbide are as follows.
MC carbides are harder than M 6 C carbides, and the larger the diameter, the better the wear resistance. However, if the maximum diameter of MC carbide is less than 3.5 μm, the effect of improving the wear resistance can not be obtained sufficiently, and if it exceeds 10 μm, it becomes a starting point of fracture and inhibits toughness. 0.5 to 10 μm.
同じく上記の炭化物の最大径の定義の下で、Ｍ6Ｃ炭化物の最大径は２．５μｍ以下と限定した理由は以下の通りである。
Ｍ6Ｃ炭化物はＭＣ炭化物よりも耐摩耗性に寄与しないため、２．５μｍ以下に制御することによって耐摩耗性を確保した上で靭性を向上させた。マトリックス中の微細な炭化物は結晶粒を微細に保持し靭性を向上させる効果があるためである。ここで、Ｍ6Ｃ炭化物を２．５μｍ以下としたのは、２．５μｍよりも大きいと靭性確保の効果が十分に得られないためである。
The reason why the maximum diameter of the M 6 C carbide is limited to 2.5 μm or less under the same definition of the maximum diameter of the carbide as described above is as follows.
Since M 6 C carbides do not contribute to wear resistance more than MC carbides, the toughness is improved after securing wear resistance by controlling to 2.5 μm or less. This is because the fine carbides in the matrix have the effect of finely holding the crystal grains and improving the toughness. Here, the reason why the M 6 C carbide is set to 2.5 μm or less is that if it is larger than 2.5 μm, the effect of securing the toughness can not be sufficiently obtained.
その上で、本発明では上記の最大径を有する炭化物について、１０００平方μｍ中に１個以上あればよいものとする。つまり本願発明において、ＭＣ炭化物の最大径が３．５〜１０μｍであるということは、最大径が３．５〜１０μｍの範囲内にあるＭＣ炭化物が１０００平方μｍの鋼中に少なくとも１個は存在することを意味する。従って残りのＭＣ炭化物の最長径は最大径よりも小さければ３．５〜１０μｍの範囲にあっても３.５μｍ未満でも構わないということである。なおＭ6Ｃ炭化物については下限がないので、係る個数比率を論じる必要はない。 Furthermore, in the present invention, one or more carbides having the above-described maximum diameter may be contained in 1000 μm. That is, in the present invention, the fact that the maximum diameter of MC carbide is 3.5 to 10 μm means that at least one MC carbide having a maximum diameter in the range of 3.5 to 10 μm is present in a 1000 square μm steel. It means to do. Therefore, the longest diameter of the remaining MC carbides may be in the range of 3.5 to 10 μm or less than 3.5 μm as long as it is smaller than the maximum diameter. There is no lower limit for M 6 C carbides, so it is not necessary to discuss such a number ratio.
請求項３の手段でＣ濃度差を０．５％以上と限定した理由は以下の通りである。
混合する粉末のＣの質量％の差、つまりＣの濃度差は０．５％以上とする。このように、０．５％以上とするのは、母相内のＣ濃度分布をばらつかせ、熱処理時に一部の炭化物のみの成長を促すには、０．５％以上のＣ濃度差が必要であるためである。なお、３種類以上の粉末を混合する場合は、最もＣ濃度が近い粉末同士の差が０．５％以上かどうかを判断する。
The reason why the C concentration difference is limited to 0.5% or more by the means of claim 3 is as follows.
The difference in mass% of C in the powder to be mixed, that is, the concentration difference in C, is 0.5% or more. As described above, if the content is 0.5% or more, the C concentration distribution in the matrix is dispersed, and in order to promote the growth of only a part of the carbides during the heat treatment, the C concentration difference of 0.5% or more is It is necessary. In addition, when mixing three or more types of powder, it is determined whether the difference between powders having the closest C concentration is 0.5% or more.
さらに、上記のＣ濃度が０．５％以上異なる２種類の金属粉末について、その混合比は以下の通りである。
混合量は高Ｃ濃度金属粉末の質量％を１．０とすると、低Ｃ濃度金属粉末の質量％は０．２５〜４．０が好ましい。すなわち、高Ｃ濃度金属粉末と低Ｃ濃度金属粉末の混合比は、「１．０：０．２５〜４．０」の範囲が好ましい。そして、高Ｃ濃度金属粉末と低Ｃ濃度金属粉末の混合比が、この範囲を超えて離れると、固化成形後のマトリックスのＣ濃度差が確保できず、一部の炭化物のみの成長を促すことができない。
Furthermore, the mixing ratio of the two types of metal powders different from each other by 0.5% or more of the C concentration is as follows.
When the mass percentage of the high C concentration metal powder is 1.0, the mass percentage of the low C concentration metal powder is preferably 0.25 to 4.0. That is, the mixing ratio of the high C concentration metal powder and the low C concentration metal powder is preferably in the range of “1.0: 0.25 to 4.0”. And, when the mixing ratio of the high C concentration metal powder and the low C concentration metal powder deviates beyond this range, the C concentration difference of the matrix after solidification and forming can not be secured, and only the growth of only a part of carbides is promoted. I can not
固化成型中や成形後の熱処理の適正条件は、鋼種によって異なるが、例えばＨＩＰ処理後や押出し工程中や固化成形後の成形体に１１００〜１２４０℃で２〜１２時間の熱処理が適正である。しかし、１１００℃未満では炭化物が殆ど大きくならない。また、１２４０℃を超えると、炭化物が急激に大きくなりすぎてしまい、微細な析出物が消失しやすく制御が難しい。 Although the appropriate conditions of heat treatment during solidification and formation differ depending on the steel type, for example, heat treatment at 1100 to 1240 ° C. for 2 to 12 hours is appropriate for a formed body after HIP processing, during an extrusion process or after solidification and formation. However, if the temperature is less than 1100 ° C., carbides hardly increase. If the temperature exceeds 1240 ° C., the carbides become too large rapidly, and the fine precipitates are easily lost and control is difficult.
以下、本発明について実施例および比較例によって具体的に説明する。
合金添加元素は同じで、Ｃ（炭素）濃度を振って作製した２種類あるいは３種類の金属粉末｛例えば、２種類では、０．３Ｓｉ−０．３Ｍｎ−４．２Ｃｒ−１．０Ｍｏ−１２．０Ｗ−４．６Ｖ−５．０Ｃｏ（数値は質量％）に１．３Ｃと２．５Ｃ（数値は質量％）のふたつに振って添加したものおよびそれらの残部にＦｅを加えて１００質量％としてなる２種類の金属粉末｝をガスアトマイズ法で作製し、粉末高速度工具鋼の２種類あるいは３種類の母材金属粉末とした。その後、それらを上記の１．０：０．２５〜４．０あるいは１．０：１．０：１．０〜２．０の混合比で混合した後、１１７０℃でＨＩＰ処理して固化成形し、表１に示す鋼のＡ、Ｂ、Ｃ、Ｄ、Ｅ、Ｆ、Ｇの成分組成からなる固化成形体を作製した。なお、母材金属粉末のＣ濃度差および粉末混合比は表２に示すとおりである。これらの固化成形体に対して、表２に示す各Ｎｏ．ごとに定めた調整温度および調整時間で熱処理粒度調整を行った。その後、３０ｍｍ径に鍛造加工し、１１９０℃で油冷焼入れ、５６０℃で３回焼戻し処理を行った。比較例としては、上記の粉末高速度工具鋼の母材金属粉末を表２の粉末混合比において、無しとあるものは混合を行わずに単一粉末のままとし、その他のものは、表２に示す各Ｎｏ．ごとに定めた粉末混合比で高Ｃ濃度の粉末と低Ｃ濃度の粉末の混合比を１：０．２〜５とし、１１７０℃でＨＩＰ処理して固化成形して固化成形体を作成した。なお、母材金属粉末のＣ濃度差および粉末混合比は表２に示すとおりである。これらの固化成形体に対し、成形後は熱処理粒度調整において無しとあるものは粒度調整を行わずそのまま、それ以外のものは表２に示す各Ｎｏ．ごとに定めた調整温度および調整時間で熱処理粒度調整を行い、その後、これらを３０ｍｍ径に鍛造加工し、１１９０℃で油冷焼入れ、５６０℃で３回焼戻し処理を行った。
Hereinafter, the present invention will be specifically described by way of examples and comparative examples.
The alloy addition elements are the same, and two or three types of metal powders produced by varying the C (carbon) concentration {for example, in two types, 0.3Si-0.3Mn-4.2Cr-1.0Mo-12. 0 W-4.6 V-5.0 Co (numerical value is% by mass) added by shaking to 1.3 C and 2.5 C (numerical value is% by mass) in two pieces and Fe is added to the remainder to make 100% by mass These two types of metal powders} were produced by gas atomization to form two or three types of base metal powders of powder high-speed tool steel. Thereafter, they are mixed at the above mixing ratio of 1.0: 0.25 to 4.0 or 1.0: 1.0: 1.0 to 2.0, and then subjected to HIP treatment at 1170 ° C. to solidify and form Then, a solidified formed body having component compositions of A, B, C, D, E, F and G of the steels shown in Table 1 was produced. The C concentration difference and the powder mixing ratio of the base metal powder are as shown in Table 2. With respect to these solidified molded articles, each No. 1 shown in Table 2 was obtained. The heat treatment particle size adjustment was performed at the adjustment temperature and adjustment time defined for each. Thereafter, the forging was performed to a diameter of 30 mm, oil-cooling quenching was performed at 1190 ° C., and tempering was performed three times at 560 ° C. As a comparative example, the base metal powder of the above-mentioned powder high-speed tool steel is made to be a single powder without mixing in the powder mixing ratio of Table 2, with or without being mixed, the others are shown in Table 2 Each No. shown in. The mixing ratio of the high C concentration powder to the low C concentration powder was set to 1: 0.2 to 5 at a powder mixing ratio determined for each, HIP processing was performed at 1170 ° C., and solidification was performed to prepare a solidified molded body. The C concentration difference and the powder mixing ratio of the base metal powder are as shown in Table 2. With respect to these solidified molded articles, those which are not present in the heat treatment particle size adjustment after forming are not subjected to the particle size adjustment, and those other than those shown in Table 2 are as shown in Table 2. The heat treatment particle size adjustment was performed at an adjustment temperature and an adjustment time determined for each, and then they were forged to a diameter of 30 mm, oil-quenched at 1190 ° C., and tempered three times at 560 ° C.
靱性の評価方法として、上記の焼入れ焼戻し後の試料において、ＪＩＳ３号シャルピー衝撃性試験（２ｍｍＵノッチ）を行い、シャルピー衝撃性値を測定し、表２における母材金属粉末種類が１種類の単一粉末でかつ熱処理粒度調整が無しの比較例をベンチマーク材とし、これらのベンチマーク材と比較して、靱性が同等以上（下がり幅１０％未満）であれば、表２の靱性の欄に○を、悪化（１０％以上減）であれれば×を付して評価した。また、耐摩耗性の評価方法として、上記の焼入れ焼戻し後の試料において、大越式摩耗試験を実施し、表２において、ベンチマーク材の耐摩耗性を１．０とし、これらのベンチマーク材と比較して、その倍数で耐摩耗性を評価した。なお、大越式摩耗試験の条件は、相手材リングＳＣＭ４２０、荷重６１．８Ｎ、摩耗距離２００ｍ、摩耗速度３．６２ｍｍ／ｓｅｃおよび乾式とした。 As a method of evaluating toughness, JIS No. 3 Charpy impact resistance test (2 mm U notch) is performed on the above samples after quenching and tempering to measure the Charpy impact resistance value, and a single type of base metal powder in Table 2 is used. A powder of the comparative example without heat treatment particle size adjustment is used as a benchmark material, and if the toughness is equal to or higher than that of these benchmark materials (falling width less than 10%), ○ in the column of toughness in Table 2 If it was aggravated (decreased by 10% or more), it was evaluated by marking with x. In addition, as a method of evaluating wear resistance, the above-mentioned samples after quenching and tempering were subjected to the Ohkoshi type wear test. In Table 2, the wear resistance of the benchmark material was made 1.0, and this was compared with these benchmark materials. The abrasion resistance was evaluated at multiples thereof. The conditions for the over-the-ear wear test were a mating ring SCM 420, a load of 61.8 N, a wear distance of 200 m, a wear rate of 3.62 mm / sec and a dry type.
また、炭化物は、熱処理した鋼材から縦２０ｍｍ、横２０ｍｍ、長さ１０ｍｍの角棒を切出し、湿式研磨および腐食液はピクラル液でＭＣ炭化物とＭ6Ｃ炭化物の両方を腐食させた場合と村上試薬でＭ6Ｃ炭化物のみを腐食させた場合について、光学顕微鏡にてミクロ組織を確認し、画像解析ソフトにより、ＭＣ炭化物およびＭ6Ｃ炭化物の最大径をそれぞれ算出した。その結果を表２に示す。 In addition, carbide cuts a square bar of 20 mm long, 20 mm wide and 10 mm long from heat-treated steel material, and wet polishing and corrosive liquid corroded both MC carbide and M 6 C carbide with picral liquid and Murakami reagent In the case where only M 6 C carbide was corroded, the microstructure was confirmed with an optical microscope, and the maximum diameters of MC carbide and M 6 C carbide were respectively calculated by image analysis software. The results are shown in Table 2.
表２において、比較例のＮｏ．４、Ｎｏ．１４、Ｎｏ．２３、Ｎｏ．２７、Ｎｏ．３０、Ｎｏ．３２、Ｎｏ．３５の各母材金属粉末種類１種類からなる単一組成の粉末を作製してベンチマーク材とした。これらの比較例のベンチマーク材については、各単一組成であるので母材金属粉末のＣ濃度差は無いので０％であり、粉末混合比は無し、かつ熱処理粒度調整も無しであることから、ＭＣ炭化物は３．５μｍよりも小さく、一方、Ｍ6Ｃ炭化物径も２．５μｍ以下で小さく、粗大な３．５μｍ以上の炭化物は存在しない。しかし、これらのベンチマーク材はＭＣ炭化物が３．５μｍより小さく、したがって、請求項で規定する３．５〜１０μｍの範囲外であるので切削工具や金型等に使用する際に要求される耐摩耗性が劣る。すなわち、これらは、母材金属粉末の種類が１種類であり、熱処理粒度調整も無しのためＭＣ炭化物が粗大化しないので、耐摩耗性が最も低く、ベンチマークの１である。 In Table 2, No. 1 of the comparative example. 4, no. 14, no. 23, no. 27, No. 30, No. 32, No. A powder of a single composition consisting of one type of each of the 35 base metal powder types was prepared and used as a benchmark material. The benchmark materials of these comparative examples have 0% because there is no difference in C concentration of the base metal powder because they are each single composition, there is no powder mixing ratio, and no heat treatment particle size adjustment, The MC carbide is smaller than 3.5 μm, while the M 6 C carbide diameter is also smaller than 2.5 μm, and there is no coarse carbide of 3.5 μm or more. However, since these benchmark materials have an MC carbide smaller than 3.5 μm and therefore outside the range of 3.5 to 10 μm specified in the claims, the wear resistance required when used for cutting tools, dies, etc. Poor sex. That is, since the type of the base metal powder is one type, and the MC carbides are not coarsened because the heat treatment particle size adjustment is not performed, the wear resistance is the lowest, which is one of the benchmark.
比較例のＮｏ．５、１５、２４は、２種類の粉末を母材金属粉末に作製するので母材金属粉末にＣ濃度差はあるが、熱処理粒度調整は無しであるので、ＭＣ炭化物は３．５μｍよりも微細なままであるために、耐摩耗性は１．１で低い。比較例のＮｏ．６、Ｎｏ．１７は、熱処理粒度調整の温度が１０８０℃と低く、ＭＣ炭化物は３．５μｍよりも微細であるため、耐摩耗性が１．２、１．１といずれも低い。比較例のＮｏ．７は、母材金属粉末種類１種類からなる単一組成の粉末であるため、母材金属粉末のＣ濃度差がなく０であり、熱処理粒度調整を行った時に、ＭＣ炭化物は粗大化せず、Ｍ6Ｃ炭化物は２．５μｍより大きく、炭化物が粗大化し、靱性が×である。比較例のＮｏ．８、９、１６は、２種類の母材金属粉末の熱処理粒度調整を行っているが、母材金属粉末のＣ濃度差が、Ｎｏ．８、１６では０．２５％、Ｎｏ．９では０．４５％と少なく、熱処理粒度調整を行った時に、Ｍ6Ｃ炭化物が粗大化したので、靱性は×である。比較例のＮｏ．１０は、２種類の母材金属粉末の熱処理粒度調整の温度が１２５０℃と高いため、ＭＣ炭化物およびＭ6Ｃ炭化物が粗大化し、靱性が×である。比較例のＮｏ．１８は、２種類の母材金属粉末の混合比が大きく、熱処理粒度調整の温度が１２５０℃と高いため、ＭＣ炭化物およびＭ6Ｃ炭化物が粗大化し、靱性が×である。比較例のＮｏ．１１、Ｎｏ．１９は、２種類の母材金属粉末の混合比が大きいので、母材のＣ濃度差が確保できず、Ｍ6Ｃ炭化物が粗大化し、靱性が×である。比較例のＮｏ．２５は、熱処理粒度調整が無しであるので、ＭＣ炭化物は３．５μｍよりも微細であるために、耐摩耗性は１．２で低い。比較例のＮｏ．２９は、熱処理粒度調整の温度が１２５０℃と高いため、ＭＣ炭化物およびＭ6Ｃ炭化物が粗大化し、靱性が×である。 No. of the comparative example. No.5,15,24 make two types of powders into base metal powder, so there is a difference in C concentration in the base metal powder, but there is no adjustment of heat treatment particle size, so MC carbide is finer than 3.5 μm In order to remain the same, the abrasion resistance is low at 1.1. No. of the comparative example. 6, No. In No. 17, the temperature of heat treatment particle size adjustment is as low as 1080 ° C., and the MC carbide is finer than 3.5 μm, so the wear resistance is as low as 1.2 and 1.1. No. of the comparative example. 7 is a powder of a single composition consisting of one type of base metal powder, there is no difference in C concentration in the base metal powder, and it is 0. When heat treatment particle size adjustment is performed, MC carbide does not coarsen. , M 6 C carbides are larger than 2.5 μm, carbides are coarsened, and toughness is ×. No. of the comparative example. No.8, 9 and 16 perform heat treatment particle size adjustment of two types of base metal powder, but the C concentration difference of the base metal powder is No. 6 8 and 16 0.25%, No. In the case of No. 9, the amount is as small as 0.45%, and when the heat treatment particle size adjustment is performed, the M 6 C carbide is coarsened, so the toughness is x. No. of the comparative example. In No. 10, since the temperature of heat treatment particle size adjustment of two types of base metal powders is as high as 1250 ° C., MC carbide and M 6 C carbide become coarse and toughness is ×. No. of the comparative example. No. 18 has a large mixing ratio of the two base metal powders, and the temperature of heat treatment particle size adjustment is as high as 1250 ° C., so MC carbide and M 6 C carbide become coarse and toughness is ×. No. of the comparative example. 11, No. In No. 19, since the mixing ratio of the two types of base metal powders is large, the C concentration difference of the base material can not be secured, and the M 6 C carbide becomes coarse and the toughness is ×. No. of the comparative example. Since No. 25 has no heat treatment particle size adjustment, the MC carbide is finer than 3.5 μm, so the wear resistance is as low as 1.2. No. of the comparative example. In No. 29, since the temperature of heat treatment particle size adjustment is as high as 1250 ° C., MC carbide and M 6 C carbide become coarse and the toughness is ×.
上記の比較例に対し、本発明例であるＮｏ．１〜３、Ｎｏ．１２〜１３、Ｎｏ．２０〜２２、Ｎｏ．２６、Ｎｏ．２８、Ｎｏ．３１、およびＮｏ．３３〜３４は、いずれも本発明の請求項の条件を満足していることから、靱性は○でかつ耐摩耗性に優れていることが分かる。 With respect to the above-described comparative example, the No. 1 and No. 2 which are inventive examples. No. 1 to 3, No. 12-13, no. 20-22, no. 26, no. 28, No. 31, and no. All of the samples No. 33 to No. 34 satisfy the conditions of the claims of the present invention, so it is understood that the toughness is 靱 and the wear resistance is excellent.
以上述べたように、本発明における粉末高速工具鋼を、母材金属粉末のＣ濃度が０．５０％以上異なる２種類以上の金属粉末を母材に用いて焼結し、さらに熱処理により適性大きさの３．５〜１０μｍのＭＣ炭化物と微細なＭ6Ｃ炭化物が混在する組織とすることで、靱性と耐摩耗性を兼ね備えた粉末高速度工具鋼が得られた。 As described above, the powder high-speed tool steel of the present invention is sintered using two or more types of metal powders different in C concentration of the base metal powder by 0.50% or more as the base material, and further heat treatment The powder high-speed tool steel having both toughness and wear resistance was obtained by forming a structure in which 3.5 to 10 μm MC carbide and fine M 6 C carbide are mixed.
Claims (1)
または、
質量％で、Ｃ：１．３０〜２．３０％、Ｓｉ：０．１〜１．０％、Ｍｎ：０．１〜１．０％、Ｃｒ：３．０〜５．０％、Ｍｏ：０．５〜５.０％、Ｗ：５．０〜２０．０％、Ｖ：３．０〜７．５％、Ｃｏ：１０．０％以下（ただし０％は含まない。）の成分組成、
の粉末高速度鋼の成分組成を含有し、残部Ｆｅおよび不可避的不純物よりなる金属粉末のうち、Ｃ濃度が０．５％以上異なる２種類以上の金属粉末を混合して固化成形した鋼であり、該鋼中にある炭化物のうち、ＭＣ炭化物の最大径は３．５〜１０μｍ、Ｍ6Ｃ炭化物の最大径は２．５μｍ以下を満たすことを特徴とする粉末高速度工具鋼。 C: 1.30 to 2.30%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.0%, Cr: 3.0 to 5.0%, Mo: Component composition of 0.5 to 5.0%, W: 5.0 to 20.0%, V: 3.0 to 7.5%,
Or
C: 1.30 to 2.30%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.0%, Cr: 3.0 to 5.0%, Mo: Component composition of 0.5 to 5.0%, W: 5.0 to 20.0%, V: 3.0 to 7.5%, Co: 10.0% or less (but not including 0%) ,
The metal powder that contains the component composition of the powder high speed steel and is formed by mixing two or more types of metal powder different in C concentration by 0.5% or more among metal powders consisting of the balance Fe and unavoidable impurities A powder high-speed tool steel characterized in that among carbides in the steel, the maximum diameter of MC carbides is 3.5 to 10 μm, and the maximum diameter of M 6 C carbides is 2.5 μm or less.
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