JP2006089784A - Bn-containing free cutting steel - Google Patents
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Abstract
Description
本発明は、快削鋼に関し、特に切削する際の工具寿命に優れたものに関する。 The present invention relates to free-cutting steel, and more particularly to a material having excellent tool life during cutting.
Ｐｂを含有した快削鋼は被削性が良好なため汎用的に用いられている。しかしながら、Ｐｂは有毒性のためハンダや銃弾などでの使用が制限されるようになり、快削鋼においてもＰｂを含有しない鋼種に対する要望は強く、種々の非Ｐｂ系快削鋼が提案されている。 Free-cutting steel containing Pb is widely used because of good machinability. However, since Pb is toxic, its use in solders and bullets has been restricted, and there is a strong demand for steel types that do not contain Pb even in free cutting steel, and various non-Pb free cutting steels have been proposed. Yes.
Ｐｂに替わり特殊な成分を用いたものとして特許文献１にはＮｄを添加したＰｂ非添加型の快削非調質鋼が開示されている。Ｎｄは溶鋼の比較的高温の時期にＭｎＳの生成核となるＮｄ2Ｓ2を微細に分散させるので、それを生成核とするＭｎＳは球状となり、固溶されるＦｅ分も少なくチップブレーカとして有効である。 Patent Document 1 discloses a non-Pb-added free-cutting non-heat treated steel to which Nd is added as a special component instead of Pb. Nd finely disperses Nd 2 S 2 that forms MnS nuclei at a relatively high temperature of the molten steel, so MnS that forms nuclei has a spherical shape and is effective as a chip breaker with less solid solution of Fe. It is.
Ｐｂに替わる快削性介在物にＢＮを用いた鋼として特許文献２には機械構造用鋼、特許文献３には非調質鋼、特許文献４には浸炭用鋼が開示されている。これらの鋼ではＢＮ析出物が硫化物やＰｂ析出物より小さく微細で、高温に対しても安定なため、鋼に要求される快削性以外の特性に及ぼす影響が少ないことを利用している。 As steels using BN as free-cutting inclusions instead of Pb, Patent Document 2 discloses mechanical structural steel, Patent Document 3 discloses non-heat treated steel, and Patent Document 4 discloses carburizing steel. These steels utilize the fact that BN precipitates are smaller and finer than sulfides and Pb precipitates and are stable to high temperatures, so that they have little effect on properties other than the free machinability required for steels. .
特許文献５にはＰｂ非添加系とし、Ｎｂを添加し、その酸化物、炭化物、窒化物および炭窒化物の一種以上をＭｎＳ系介在物の析出核としたＳ系快削鋼の機械構造用鋼が開示されている。快削性を向上させるため、Ｓ／Ｏを特定の範囲とし、更にＳｎ，Ｓｂ、Ｃａ，Ｍｇを添加している。 Patent Document 5 discloses a mechanical structure of S-based free-cutting steel in which Pb is not added, Nb is added, and one or more of oxides, carbides, nitrides, and carbonitrides thereof are used as precipitation nuclei of MnS inclusions. Steel is disclosed. In order to improve the free-cutting property, S / O is set to a specific range, and Sn, Sb, Ca, Mg are further added.
しかしながら、特許文献１に記載のＰｂ非添加型の快削非調質鋼は成分組成に特殊な元素であるＮｄを用いるため、資源環境的に制約が大きく、製造コストが高い。特許文献２、３、４に記載の鋼は快削性元素としてＢＮを用いるが、Ｐｂ系快削鋼と比較して被削性が十分とは言い難い。特許文献５記載の鋼はその用途からＳ添加量が制約を受け、快削鋼としての被削性が十分でなくＰｂ系快削鋼に及ばない。 However, the non-Pb-added free-cutting tempered steel described in Patent Document 1 uses Nd, which is a special element in the component composition, and therefore has a great resource environment limitation and high manufacturing cost. The steels described in Patent Documents 2, 3, and 4 use BN as a free-cutting element, but it is difficult to say that machinability is sufficient as compared with Pb-based free-cutting steel. The steel described in Patent Document 5 is limited in the amount of S added due to its use, and the machinability as free-cutting steel is not sufficient, and does not reach Pb-based free-cutting steel.
本発明は、快削性を付与する化合物としてＢＮを用い、Ｐｂ系快削鋼と同等以上の被削性を有し、特に工具寿命に優れた快削鋼を提供することを目的とする。 An object of the present invention is to provide a free-cutting steel that uses BN as a compound that imparts free-cutting properties, has machinability equivalent to or better than that of Pb-based free-cutting steel, and is particularly excellent in tool life.
本発明者等は快削元素としてＢＮを用いる快削鋼を対象に、工具寿命の観点から被削性について鋭意検討を行い、鋼中に一定の大きさ以上の大型ＢＮ介在物と一定の大きさ以下の微細な硫化物が共存すると工具寿命が著しく改善されることを見出した。 The present inventors have intensively studied machinability from the viewpoint of tool life for free-cutting steel using BN as a free-cutting element, and have large BN inclusions and a certain size in the steel. It has been found that the tool life is remarkably improved when fine sulfides of less than 5 mm coexist.
本発明は以上の知見を基に更に検討を加えてなされたもので、すなわち、本発明は、
１ 質量％でＣ：０．０１〜１．２％、Ｓｉ：０．１０超え〜１．５％、Ｍｎ：０．３〜２．０％、Ｓ：０．０１〜０．２％、Ｂ：０．００５０〜０．０１５０％、Ｎ：０．０１００〜０．０２００％、Ａｌ：０．０１〜０．１％、Ｎｂ：０．００５〜０．０５％、Ｎ／Ｂ：１〜３、残部Ｆｅ及び不可避的不純物で、１ｍｍ2当たりに円相当径で１０μm以上のＢＮ介在物を５０個以上と円相当径で３μm以下の硫化物を５００個以上同時に有することを特徴とする快削鋼。
２ １記載の成分組成に更に質量％でＮｉ：０．０１〜２．０％、Ｃｒ：０．０１〜２．０％、Ｍｏ：０．０１〜２．０％の一種または二種以上を添加したことを特徴とする快削鋼。
３ １または２記載の成分組成に更に質量％でＶ：０．００１〜１．０％、Ｔｉ：０．００１〜１．０％の一種又は二種を添加したことを特徴とする快削鋼。
４ １乃至３の何れか一つに記載の成分組成に更に質量％でＣａ：０．０００１〜０．００９０％、Ｓｅ：０．０２〜０．３０％、Ｔｅ：０．０３〜０．１５％、Ｂｉ：０．０２〜０．２０％、Ｓｎ：０．００３〜０．０２０％、Ｃｕ：０．０５〜０．５％、Ｚｒ：０．００５〜０．０９％、Ｍｇ：０．０００５〜０．０８０％の一種または二種以上を含有することを特徴とする快削鋼。
The present invention has been made on the basis of the above findings and further studies, that is, the present invention,
1% by mass C: 0.01 to 1.2%, Si: more than 0.10 to 1.5%, Mn: 0.3 to 2.0%, S: 0.01 to 0.2%, B : 0.0050 to 0.0150%, N: 0.0100 to 0.0200%, Al: 0.01 to 0.1%, Nb: 0.005 to 0.05%, N / B: 1 to 3 Further, free cutting characterized by having 50 or more BN inclusions having an equivalent circle diameter of 10 μm or more per 1 mm 2 and 500 or more sulfides having an equivalent circle diameter of 3 μm or less per 1 mm 2 with the balance Fe and inevitable impurities. steel.
21 In addition to the component composition described in 1, one or more of Ni: 0.01 to 2.0%, Cr: 0.01 to 2.0%, Mo: 0.01 to 2.0% in mass%. Free-cutting steel characterized by the addition.
3. Free-cutting steel characterized by further adding one or two of V: 0.001 to 1.0% and Ti: 0.001 to 1.0% by mass% to the component composition described in 1 or 2 .
4 In addition to the component composition according to any one of 1 to 3, Ca: 0.0001 to 0.0090%, Se: 0.02 to 0.30%, Te: 0.03 to 0.15 in mass%. %, Bi: 0.02 to 0.20%, Sn: 0.003 to 0.020%, Cu: 0.05 to 0.5%, Zr: 0.005 to 0.09%, Mg: 0.0. A free-cutting steel characterized by containing one or more of 0005 to 0.080%.
本発明によれば、地球環境上の悪影響を及ぼすことが懸念されるＰｂを添加せずにＰｂ添加系と同等の快削性を有し、工具寿命において優れる快削鋼が得られ、産業上極めて有用である。Ｐｂを添加した場合は更に快削性、工具寿命が向上する。 According to the present invention, free-cutting steel having a free cutting property equivalent to that of a Pb-added system and having an excellent tool life can be obtained without adding Pb, which is likely to have an adverse effect on the global environment. Very useful. When Pb is added, the free cutting property and the tool life are further improved.
本発明における成分限定理由、ＢＮ介在物と硫化物の限定理由について説明する。 The reasons for limiting the components in the present invention and the reasons for limiting BN inclusions and sulfides will be described.
［成分限定理由］
Ｃ
Ｃは鋼の強度を確保するために必要な元素である。その含有量が０．０１％未満では必要な強度が確保できない。一方、１．２％を超えると靭性が低下するため、０．０１〜１．２％とする。
[Reason for ingredient limitation]
C
C is an element necessary for ensuring the strength of steel. If the content is less than 0.01%, the required strength cannot be ensured. On the other hand, if it exceeds 1.2%, the toughness decreases, so 0.01 to 1.2%.
Ｓｉ
Ｓｉは脱酸に必要な元素で、その含有量が０．１０％以下では十分な脱酸効果が得られない。一方、１．５％を超えるとフェライトが硬化して被削性が低下するため、０．１０超え〜１．５％とする。
Si
Si is an element necessary for deoxidation, and if its content is 0.10% or less, a sufficient deoxidation effect cannot be obtained. On the other hand, if it exceeds 1.5%, the ferrite is cured and the machinability is lowered, so that it exceeds 0.10 to 1.5%.
Ｍｎ
Ｍｎは強度及び靭性に大きな影響を及ぼす元素であり、その含有量が０．３％未満では十分な強度が得られない。一方、２．０％を超えると靭性が低下するため、０．３〜２．０％とする。
Mn
Mn is an element having a great influence on strength and toughness. If its content is less than 0.3%, sufficient strength cannot be obtained. On the other hand, if it exceeds 2.0%, the toughness decreases, so 0.3 to 2.0%.
Ｓ
Ｓは被削性に有効な硫化物を形成する元素である。その含有量が０．０１％未満では硫化物量が少なく被削性を向上させる効果が十分でない。一方、０．２％を超えると熱間加工性が低下し、圧延表面疵が生じやすくなるため０．０１〜０．２％とする。
S
S is an element that forms a sulfide effective for machinability. If the content is less than 0.01%, the amount of sulfide is small and the effect of improving machinability is not sufficient. On the other hand, if it exceeds 0.2%, the hot workability is lowered and rolling surface flaws are liable to occur, so the content is made 0.01 to 0.2%.
Ｂ
Ｂは被削性、特に工具寿命を向上させるＢＮを生成させるために必要な元素であり、０．００５０％未満では被削性を確保するために十分な量のＢＮを生成することができない。一方、０．０１５０％を超えると靭性が低下してしまうため、０．００５０〜０．０１５０％とする。
B
B is an element necessary for generating BN that improves machinability, in particular, the tool life. If it is less than 0.0050%, a sufficient amount of BN cannot be generated to ensure machinability. On the other hand, if it exceeds 0.0150%, the toughness will decrease, so 0.0050 to 0.0150%.
Ｎ
Nは被削性を向上させるＢＮを生成するために必要な元素であり、０．０１００％未満では被削性を確保するために必要な量のＢＮを生成することができない。一方、０．０２００％を超えると靭性あるいは疲労特性が低下してしまうため０．０１００〜０．０２００％とする。
N
N is an element necessary for generating BN that improves machinability. If it is less than 0.0100%, an amount of BN necessary for ensuring machinability cannot be generated. On the other hand, if it exceeds 0.0200%, the toughness or fatigue characteristics will be lowered, so 0.0100 to 0.0200%.
Ａｌ
Ａｌは脱酸に必要な元素で、また工具面上にＡｌＮ被膜を生成させ、切削中の工具の拡散磨耗を抑制するために必要である。０．０１％未満ではその効果が得られないため、０．０１％以上、好ましくは０．０２％超えとする。一方、０．１％を越えるとその効果が飽和し硬質のアルミナ系酸化物が増加し、疲労特性が低下するため、０．０１、好ましくは０．０２超えから０．１％とする。
Al
Al is an element necessary for deoxidation, and is necessary for generating an AlN coating on the tool surface and suppressing diffusion wear of the tool during cutting. If less than 0.01%, the effect cannot be obtained, so 0.01% or more, preferably over 0.02%. On the other hand, if it exceeds 0.1%, the effect is saturated and hard alumina-based oxides are increased, and the fatigue characteristics are deteriorated. Therefore, the content is made 0.01, preferably from 0.02 to 0.1%.
Ｎｂ
本発明ではＮｂは微細硫化物を形成し、同時にＢＮと共存して被削性を著しく向上させる重要な元素である。このような効果を得るため０．００５％以上とする。一方、含有量が０．０５％を超えると熱間加工性が低下し、圧延表面疵が生じ易くなるため０．００５〜０．０５％とする。
Nb
In the present invention, Nb is an important element that forms fine sulfides and at the same time coexists with BN and significantly improves the machinability. In order to obtain such an effect, the content is made 0.005% or more. On the other hand, if the content exceeds 0.05%, the hot workability is lowered and rolling surface flaws are liable to occur, so 0.005 to 0.05%.
Ｎ／Ｂ
Ｎ／Ｂが１未満ではｆｒｅｅＢ量が増大し、焼入れ性が向上して機械的性質を劣化させる。一方、Ｎ／Ｂが３を超えるとｆｒｅｅＮ量が増大して歪時効が生じやすくなり冷間加工性が劣化するため、１〜３とする。
N / B
If N / B is less than 1, the amount of freeB increases, the hardenability is improved and the mechanical properties are deteriorated. On the other hand, if N / B exceeds 3, the amount of freeN increases, strain aging is likely to occur, and cold workability deteriorates.
本発明鋼の基本成分系は以上のとおりであるが、更に所望する特性を向上させる場合、Nｉ、Ｃｒ、Ｍｏ、Ｖ、Ｔｉ、Ｃａ、Ｓｅ、Ｔｅ、Ｂｉ、Ｓｎ、Ｃｕ、Ｚｒ、Ｍｇの一種または二種以上を選択的に添加することができる。数値は質量％を示す。 Although the basic component system of the steel of the present invention is as described above, when further improving desired characteristics, Ni, Cr, Mo, V, Ti, Ca, Se, Te, Bi, Sn, Cu, Zr, Mg One kind or two or more kinds can be selectively added. A numerical value shows the mass%.
強度を向上させる場合、Nｉ、Ｃｒ、Ｍｏの一種または二種以上を含有することができる。Ｎｉを含有する場合は０．０１〜２．０％、Ｃｒを含有する場合は０．０１〜２．０％、Ｍｏを含有する場合は０．０１〜２．０％とする。それぞれの元素の添加量が下限値未満ではその効果が得られず、一方、上限値を超えると経済的に不利となり、強度が過度に上昇し、被削性を劣化させる。 When improving strength, one or more of Ni, Cr and Mo can be contained. When Ni is contained, 0.01 to 2.0%, when Cr is contained, 0.01 to 2.0%, and when Mo is contained, 0.01 to 2.0%. If the addition amount of each element is less than the lower limit value, the effect cannot be obtained. On the other hand, if the addition amount exceeds the upper limit value, it is economically disadvantageous, the strength is excessively increased, and the machinability is deteriorated.
強度、靭性を向上させる場合、Ｖ，Ｔｉの一種または二種を含有することができる。Ｖを含有する場合は０．００１〜１．０％、Ｔｉを含有する場合は０．００１〜１．０％とする。それぞれの元素の添加量が下限値未満では微細な炭化物の析出量が少なく、その効果が得られず、一方、上限値を超えると強度が過度に上昇し、被削性を劣化させる。 In the case of improving strength and toughness, one or two of V and Ti can be contained. When it contains V, it is 0.001 to 1.0%, and when it contains Ti, it is 0.001 to 1.0%. If the amount of each element added is less than the lower limit, the amount of fine carbides precipitated is small and the effect cannot be obtained. On the other hand, if the amount exceeds the upper limit, the strength increases excessively and the machinability deteriorates.
被削性を向上させる場合、Ｃａ、Ｓｅ、Ｔｅ、Ｂｉ、Ｓｎ、Ｃｕ、Ｚｒ、Ｍｇの一種または二種以上を含有することができる。 When improving machinability, one or more of Ca, Se, Te, Bi, Sn, Cu, Zr, and Mg can be contained.
Ｃａを含有する場合は０．０００１〜０．００９０％、Ｓｅを含有する場合は０．０２〜０．３０％、Ｔｅを含有する場合は０．０３〜０．１５％、Ｂｉを含有する場合は０．０２〜０．２０％、Ｓｎを含有する場合は０．００３〜０．０２０％、Ｃｕを含有する場合は０．０５〜０．５％、Ｚｒを含有する場合は０．００５〜０．０９％、Ｍｇを含有する場合は０．０００５〜０．０８０％とする。それぞれの元素の添加量が下限値未満ではその効果が得られず、一方、上限値を超えるとその効果が飽和し経済的にも不利となる。 When Ca is contained, 0.0001 to 0.0090%, when Se is contained, 0.02 to 0.30%, when Te is contained, 0.03 to 0.15%, and Bi is contained. Is 0.02 to 0.20%, 0.003 to 0.020% if it contains Sn, 0.05 to 0.5% if it contains Cu, 0.005 if it contains Zr When it contains 0.09% and Mg, it is made 0.0005 to 0.080%. If the addition amount of each element is less than the lower limit value, the effect cannot be obtained. On the other hand, if the addition amount exceeds the upper limit value, the effect is saturated and economically disadvantageous.
尚、上述した成分組成の鋼に更にＰｂを添加して、被削性をより向上させることも可能である。添加する場合はＰｂの添加量を０．０１〜０．４０％とすると機械的特性の劣化が小さく好ましい。 It is also possible to further improve the machinability by adding Pb to the steel having the above-described component composition. In the case of addition, it is preferable that the addition amount of Pb is 0.01 to 0.40% because the deterioration of mechanical properties is small.
［ＢＮ介在物と硫化物の限定理由］
本発明では、鋼中のＢＮ介在物と硫化物の形態を規定する。ＢＮ介在物の切欠き効果により発生した切屑中の亀裂の伝播、成長を微細な硫化物により助長し、被削性において工具寿命を向上させるため、ＢＮ介在物は円相当直径で１０μm以上とし、１ｍｍ2当たり５０個以上とする。なお、ＢＮ介在物は円相当直径で３００μmを超えると効果が飽和するので、好ましくは円相当直径で１０〜３００μmの範囲とする。
[Reason for limitation of BN inclusions and sulfides]
In the present invention, the form of BN inclusions and sulfides in steel is defined. In order to promote the propagation and growth of cracks in the chips generated by the notch effect of BN inclusions with fine sulfides and improve the tool life in machinability, the BN inclusions have a circle equivalent diameter of 10 μm or more, 50 or more per 1 mm 2 . In addition, since an effect will be saturated if a BN inclusion exceeds 300 micrometers in a circle equivalent diameter, Preferably it shall be the range of 10-300 micrometers in a circle equivalent diameter.
ＢＮ介在物と共に１ｍｍ2当たりに観察される硫化物は円相当直径で３μｍ以下とし、５００個以上とする。なお、硫化物は円相当直径で０．０１μm未満では効果が飽和するので、好ましくは円相当直径で０．０１〜３μmの範囲とする。 The sulfide observed per 1 mm 2 together with the BN inclusions has a circle equivalent diameter of 3 μm or less and 500 or more. The effect of the sulfide is saturated when the equivalent circle diameter is less than 0.01 μm, so the equivalent circle diameter is preferably in the range of 0.01 to 3 μm.
本発明に係る快削鋼は、定法に従い溶鋼から製造した本発明範囲内の成分組成の鋼片を定法の棒鋼圧延により所望する寸法の棒鋼にすることが可能である。 In the free-cutting steel according to the present invention, a steel slab having a component composition within the range of the present invention manufactured from molten steel according to a regular method can be made into a steel bar having a desired size by regular steel bar rolling.
本発明を機械構造用鋼（Ｓ４５Ｃ系）、肌焼鋼（ＳＣＭ４２０Ｈ系）、非調質鋼（Ｓ４５ＣＶ系）に適用した場合について実施例によりその効果を説明する。 The effects of the present invention applied to steel for machine structural use (S45C series), case hardening steel (SCM420H series), and non-tempered steel (S45CV series) will be described with reference to examples.
［機械構造用鋼（Ｓ４５Ｃ系）］
表１に示す成分組成の鋼を鋳造断面４００×３１０（ｍｍ）鋼塊に鋳造後、直径８０ｍｍの棒鋼に熱間圧延し、介在物測定、被削性試験および表面疵試験を行った。表１に示す供試鋼はＮｏ．１〜６が本発明範囲内の化学成分を有する鋼で、Ｎｏ．７〜１１は比較鋼、Ｎｏ．１２は参考例でＳ４５Ｃに０．２３％Ｐｂを添加した。
[Mechanical structural steel (S45C)]
Steel having the component composition shown in Table 1 was cast into a steel ingot having a cast cross section of 400 × 310 (mm), and then hot-rolled to a steel bar having a diameter of 80 mm, and inclusion measurement, machinability test, and surface flaw test were performed. The test steels shown in Table 1 are No. Nos. 1 to 6 are steels having chemical components within the scope of the present invention. 7 to 11 are comparative steels, No. No. 12 was a reference example, and 0.23% Pb was added to S45C.
介在物測定は介在物の生成状況を調査するため棒鋼の径方向、軸方向のほぼ中間部で縦１ｍｍ×横１ｍｍの領域について行い、ＢＮ介在物、硫化物毎に画像解析装置により面積を測定し円相当径および円相当径毎の個数を求めた。画像解析装置に入力する画像は倍率×４００の光学顕微鏡による観察像とした。 Inclusion measurement is performed on a 1 mm x 1 mm area in the middle of the steel bar in the radial and axial directions in order to investigate the formation of inclusions, and the area of each BN inclusion and sulfide is measured by an image analyzer. The equivalent circle diameter and the number for each equivalent circle diameter were determined. The image input to the image analysis apparatus was an observation image with an optical microscope with a magnification of 400.
被削性試験は外周旋削とドリル穴開けについて行い、外周旋削については工具寿命、切屑形状、最大表面粗さで評価し、ドリル穴開けは工具寿命で評価した。表２に被削性試験の内容を示す。 The machinability test was performed for peripheral turning and drilling. For peripheral turning, the tool life, chip shape, and maximum surface roughness were evaluated, and for drilling, the tool life was evaluated. Table 2 shows the details of the machinability test.
表面疵試験は、３００ｍｍ長さに棒鋼を切断し、酸洗後、表面傷の総面積を求めた。表面疵は鱗上にひび割れた形態となるため占有する面積で評価した。 In the surface wrinkle test, a steel bar was cut to a length of 300 mm, and after pickling, the total area of surface flaws was determined. Since the surface wrinkles were cracked on the scale, the area occupied was evaluated.
表３に供試材Ｎｏ．１〜１２のそれぞれについて行った各試験の結果を示す。供試材Ｎｏ．１〜６は本発明範囲内の成分組成とＢＮ介在物、硫化物の生成状態が本発明範囲内となる本発明例で、Ｐｂ添加快削鋼（Ｎｏ．１２）に対して同等以上の被削性を有している。 Table 3 shows the sample Nos. The result of each test done about each of 1-12 is shown. Specimen No. Nos. 1 to 6 are examples of the present invention in which the component composition within the scope of the present invention and the formation state of BN inclusions and sulfides are within the scope of the present invention. Has machinability.
比較例Ｎｏ．７は、Ｎｂ量が本発明範囲外で少なく、微細硫化物の個数が少ないため、被削性が本発明例に対し劣っている。 Comparative Example No. In No. 7, the amount of Nb is small outside the range of the present invention, and the number of fine sulfides is small, so that the machinability is inferior to the examples of the present invention.
比較例Ｎｏ．８は、Ｎｂ量が本発明範囲外で多く、被削性は本発明例と同等であるが、表面疵が本発明例より多く発生している。 Comparative Example No. In No. 8, the amount of Nb is large outside the scope of the present invention, and the machinability is equivalent to that of the present invention example, but surface flaws are generated more than in the present invention example.
比較例Ｎｏ．９は、Ｂ量が本発明範囲外で少なく、本発明で規定する大きさのＢＮ介在物の個数が少ないため被削性が本発明例に対して劣っている。 Comparative Example No. In No. 9, the amount of B is small outside the scope of the present invention, and the number of BN inclusions of the size specified in the present invention is small, so that the machinability is inferior to the examples of the present invention.
比較例Nｏ．１０は、Ｓ量が本発明範囲外で少なく、本発明で規定する大きさの硫化物の個数が少なく被削性が本発明例に対し劣っている。 Comparative Example No. No. 10, the amount of S is small outside the scope of the present invention, the number of sulfides of the size specified in the present invention is small, and the machinability is inferior to the examples of the present invention.
比較例Ｎｏ．１１は、Ｓ量が本発明範囲外で多く、被削性は本発明例と同等であるが、熱間延性が低く、表面疵が本発明例より多く発生している。 Comparative Example No. No. 11 has a large amount of S outside the range of the present invention, and machinability is equivalent to that of the present invention example. However, hot ductility is low and surface flaws are generated more than in the present invention example.
［肌焼鋼（ＳＣＭ４２０H系）］
表４に示す成分組成の鋼を鋳造断面４００×３１０（ｍｍ）鋼塊に鋳造後、直径８０ｍｍの棒鋼に熱間圧延し、介在物測定、被削性試験および表面疵試験を行った。表４に示す供試鋼はＮｏ．１３〜１８が本発明範囲内の化学成分を有する鋼で、Ｎｏ．１９〜２３は比較鋼、Ｎｏ．２４は参考例でＳＣｒ４２０Ｈに０．１８％Ｐｂを添加した。
[Skin-hardened steel (SCM420H series)]
Steel having the component composition shown in Table 4 was cast into a steel ingot having a cast cross section of 400 × 310 (mm), and then hot-rolled into a steel bar having a diameter of 80 mm, and the inclusion measurement, machinability test, and surface flaw test were performed. The test steels shown in Table 4 are No. Nos. 13 to 18 are steels having chemical components within the scope of the present invention. Nos. 19 to 23 are comparative steels. 24 is a reference example, and 0.18% Pb was added to SCr420H.
介在物測定，被削性試験および表面疵試験は、機械構造用鋼Ｓ４５Ｃの試験方法に準じて行った。 Inclusion measurement, machinability test, and surface flaw test were performed in accordance with the test method for steel S45C for machine structural use.
表５に供試材Ｎｏ．１３〜２４のそれぞれについて行った各試験の結果を示す。供試材Ｎｏ．１〜６は本発明範囲内の成分組成とＢＮ介在物、硫化物の生成状態が本発明範囲内となる本発明例で、Ｐｂ添加快削鋼（Ｎｏ．２４）に対して同等以上の被削性を有している。 Table 5 shows the sample No. The result of each test performed about each of 13-24 is shown. Specimen No. Nos. 1 to 6 are examples of the present invention in which the component composition within the scope of the present invention and the formation state of BN inclusions and sulfides are within the scope of the present invention. Has machinability.
比較例Ｎｏ．１９は、Ｎｂ量が本発明範囲外で少なく、微細硫化物の個数が少ないため、被削性が本発明例に対し劣っている。 Comparative Example No. No. 19 has an Nb content outside the range of the present invention and a small number of fine sulfides, so that machinability is inferior to the present invention example.
比較例Ｎｏ．２０は、Ｎｂ量が本発明範囲外で多く、被削性は本発明例と同等であるが、熱間延性に劣り、表面疵が本発明例より多く発生している。 Comparative Example No. No. 20 has a large amount of Nb outside the scope of the present invention, and machinability is equivalent to that of the present invention example, but is inferior in hot ductility and more surface flaws than in the present invention example.
比較例Ｎｏ．２１は、Ｂ量が本発明範囲外で少なく、本発明で規定する大きさのＢＮ介在物の個数が少ないため被削性が本発明例に対して劣っている。 Comparative Example No. In No. 21, the amount of B is small outside the scope of the present invention, and the number of BN inclusions of the size specified in the present invention is small, so that the machinability is inferior to the examples of the present invention.
比較例Nｏ．２２は、Ｓ量が本発明範囲外で少なく、本発明で規定する大きさの硫化物の個数が少なく被削性が本発明例に対し劣っている。 Comparative Example No. No. 22 has a small amount of S outside the scope of the present invention, a small number of sulfides having a size specified in the present invention, and machinability is inferior to the present invention example.
比較例Ｎｏ．２３は、Ｓ量が本発明範囲外で多く、被削性は本発明例と同等であるが、熱間延性が低く、表面疵が本発明例より多く発生している。 Comparative Example No. No. 23 has a large amount of S outside the scope of the present invention, and machinability is equivalent to that of the present invention example. However, hot ductility is low and surface flaws occur more than in the present invention example.
［非調質鋼（Ｓ４５ＣＶ系）］
表６に示す成分組成の鋼を鋳造断面４００×３１０（ｍｍ）鋼塊に鋳造後、直径８０ｍｍの棒鋼に熱間圧延し、介在物測定、被削性試験および表面疵試験を行った。供試鋼はＮｏ．２５〜３０が本発明範囲内の化学成分を有する鋼で、Ｎｏ．３１〜３５は比較鋼、Ｎｏ．３６は参考例でＳ４５ＣＶに０．２４％Ｐｂを添加した。
[Non-tempered steel (S45CV series)]
Steel having the component composition shown in Table 6 was cast into a steel ingot having a cast cross section of 400 × 310 (mm), and then hot-rolled into a steel bar having a diameter of 80 mm, and inclusion measurement, machinability test, and surface flaw test were performed. The test steel was No. Nos. 25 to 30 are steels having chemical components within the scope of the present invention. Nos. 31 to 35 are comparative steels. 36 is a reference example, and 0.24% Pb was added to S45CV.
介在物測定，被削性試験および表面疵試験は、機械構造用鋼Ｓ４５Ｃの試験方法に準じて行った。 Inclusion measurement, machinability test, and surface flaw test were performed in accordance with the test method for steel S45C for machine structural use.
表７に供試材Ｎｏ．２５〜３６のそれぞれについて行った各試験の結果を示す。供試材Ｎｏ．２５〜３０は本発明範囲内の成分組成とＢＮ介在物、硫化物の生成状態が本発明範囲内となる本発明例で、Ｐｂ添加快削鋼（Ｎｏ．３６）に対して同等以上の被削性を有している。 Table 7 shows the sample No. The result of each test performed about each of 25-36 is shown. Specimen No. 25 to 30 are examples of the present invention in which the component composition within the scope of the present invention and the formation state of BN inclusions and sulfides are within the scope of the present invention. Has machinability.
比較例Ｎｏ．３１は、Ｎｂ量が本発明範囲外で少なく、微細硫化物の個数が少ないため、被削性が本発明例に対し劣っている。 Comparative Example No. No. 31 has a small amount of Nb outside the range of the present invention and a small number of fine sulfides, so that the machinability is inferior to the examples of the present invention.
比較例Ｎｏ．３２は、Ｎｂ量が本発明範囲外で多く、被削性は本発明例と同等であるが、熱間延性に劣り、表面疵が本発明例より多く発生している。 Comparative Example No. No. 32 has a large amount of Nb outside the range of the present invention, and machinability is equivalent to the example of the present invention, but is inferior in hot ductility and generates more surface flaws than the example of the present invention.
比較例Ｎｏ．３３は、Ｂ量が本発明範囲外で少なく、本発明で規定する大きさのＢＮ介在物の個数が少ないため被削性が本発明例に対して劣っている。 Comparative Example No. In No. 33, the amount of B is small outside the scope of the present invention, and the number of BN inclusions of the size specified in the present invention is small, so that the machinability is inferior to that of the present invention.
比較例Nｏ．３４は、Ｓ量が本発明範囲外で少なく、本発明で規定する大きさの硫化物の個数が少なく被削性が本発明例に対し劣っている。 Comparative Example No. No. 34 has a small amount of S outside the scope of the present invention, a small number of sulfides having a size specified in the present invention, and machinability is inferior to that of the present invention.
比較例Ｎｏ．３５は、Ｓ量が本発明範囲外で多く、被削性は本発明例と同等であるが、熱間延性が低く、表面疵が本発明例より多く発生している。 Comparative Example No. No. 35 has a large amount of S outside the range of the present invention, and machinability is equivalent to that of the present invention example. However, hot ductility is low and surface flaws are generated more than in the present invention example.
Claims (4)
Ｃ：０．０１〜１．２％、
Ｓｉ：０．１０超え〜１．５％、
Ｍｎ：０．３〜２．０％、
Ｓ：０．０１〜０．２％、
Ｂ：０．００５０〜０．０１５０％、
Ｎ：０．０１００〜０．０２００％、
Ａｌ：０．０１〜０．１％、
Ｎｂ：０．００５〜０．０５％、
Ｎ／Ｂ：１〜３、
残部Ｆｅ及び不可避的不純物で、
１ｍｍ2当たりに円相当径で１０μm以上のＢＮ介在物を５０個以上と円相当径で３μm以下の硫化物を５００個以上同時に有することを特徴とする快削鋼。 In mass% C: 0.01-1.2%,
Si: more than 0.10 to 1.5%,
Mn: 0.3 to 2.0%,
S: 0.01-0.2%
B: 0.0050 to 0.0150%,
N: 0.0100-0.0200%,
Al: 0.01 to 0.1%,
Nb: 0.005 to 0.05%,
N / B: 1-3,
With the balance Fe and inevitable impurities,
A free-cutting steel comprising 50 or more BN inclusions having an equivalent circle diameter of 10 μm or more per 1 mm 2 and 500 or more sulfides having an equivalent circle diameter of 3 μm or less.
Ｎｉ：０．０１〜２．０％、
Ｃｒ：０．０１〜２．０％、
Ｍｏ：０．０１〜２．０％
の一種または二種以上を添加したことを特徴とする快削鋼。 The component composition according to claim 1, further in mass%, Ni: 0.01 to 2.0%,
Cr: 0.01 to 2.0%,
Mo: 0.01 to 2.0%
A free-cutting steel characterized by adding one or more of the above.
Ｖ：０．００１〜１．０％、
Ｔｉ：０．００１〜１．０％
の一種又は二種を添加したことを特徴とする快削鋼。 In addition to the component composition according to claim 1 or 2 by mass, V: 0.001 to 1.0%,
Ti: 0.001 to 1.0%
A free-cutting steel characterized by adding one or two of the above.
Ｃａ：０．０００１〜０．００９０％、
Ｓｅ：０．０２〜０．３０％、
Ｔｅ：０．０３〜０．１５％、
Ｂｉ：０．０２〜０．２０％、
Ｓｎ：０．００３〜０．０２０％、
Ｃｕ：０．０５〜０．５％、
Ｚｒ：０．００５〜０．０９％、
Ｍｇ：０．０００５〜０．０８０％
の一種または二種以上を含有することを特徴とする快削鋼。 In addition to the component composition according to any one of claims 1 to 3, by mass% Ca: 0.0001 to 0.0090%,
Se: 0.02 to 0.30%,
Te: 0.03-0.15%,
Bi: 0.02 to 0.20%,
Sn: 0.003-0.020%,
Cu: 0.05 to 0.5%,
Zr: 0.005 to 0.09%,
Mg: 0.0005 to 0.080%
A free-cutting steel characterized by containing one or more of the above.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008066194A1 (en) * | 2006-11-28 | 2008-06-05 | Nippon Steel Corporation | Free-cutting steel excellent in manufacturability |
| WO2008082153A1 (en) * | 2006-12-28 | 2008-07-10 | Posco | Eco-friendly pb-free free cutting steel with excellent machinability and hot workability |
| JP5251868B2 (en) * | 2007-10-24 | 2013-07-31 | 新日鐵住金株式会社 | Carbonitriding induction-hardened steel parts with excellent surface pressure fatigue strength at high temperatures and methods for producing the same |
| CN104789908A (en) * | 2015-05-14 | 2015-07-22 | 武汉钢铁(集团)公司 | Boron-containing low-lead composite free-cutting steel |
| JP2017057474A (en) * | 2015-09-18 | 2017-03-23 | Ｊｆｅスチール株式会社 | Free cutting steel |
| KR20190043790A (en) * | 2017-10-19 | 2019-04-29 | 주식회사 포스코 | Medium carbon free cutting steel having excellent hot workability and method for manufacturing the same |
| CN114829650A (en) * | 2019-12-23 | 2022-07-29 | 杰富意钢铁株式会社 | Free-cutting steel and method for producing same |
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2004
- 2004-09-22 JP JP2004274472A patent/JP4359548B2/en active Active
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008066194A1 (en) * | 2006-11-28 | 2008-06-05 | Nippon Steel Corporation | Free-cutting steel excellent in manufacturability |
| AU2007326255B2 (en) * | 2006-11-28 | 2010-06-24 | Nippon Steel Corporation | Free-cutting steel excellent in manufacturability |
| WO2008082153A1 (en) * | 2006-12-28 | 2008-07-10 | Posco | Eco-friendly pb-free free cutting steel with excellent machinability and hot workability |
| JP5251868B2 (en) * | 2007-10-24 | 2013-07-31 | 新日鐵住金株式会社 | Carbonitriding induction-hardened steel parts with excellent surface pressure fatigue strength at high temperatures and methods for producing the same |
| CN104789908A (en) * | 2015-05-14 | 2015-07-22 | 武汉钢铁(集团)公司 | Boron-containing low-lead composite free-cutting steel |
| JP2017057474A (en) * | 2015-09-18 | 2017-03-23 | Ｊｆｅスチール株式会社 | Free cutting steel |
| KR20190043790A (en) * | 2017-10-19 | 2019-04-29 | 주식회사 포스코 | Medium carbon free cutting steel having excellent hot workability and method for manufacturing the same |
| KR102010052B1 (en) | 2017-10-19 | 2019-08-12 | 주식회사 포스코 | Medium carbon free cutting steel having excellent hot workability and method for manufacturing the same |
| CN114829650A (en) * | 2019-12-23 | 2022-07-29 | 杰富意钢铁株式会社 | Free-cutting steel and method for producing same |
| CN114829650B (en) * | 2019-12-23 | 2023-06-02 | 杰富意钢铁株式会社 | Free-cutting steel and method for producing same |
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