JP5641992B2 - Machine structural steel with low heat treatment deformation - Google Patents

Machine structural steel with low heat treatment deformation Download PDF

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JP5641992B2
JP5641992B2 JP2011061209A JP2011061209A JP5641992B2 JP 5641992 B2 JP5641992 B2 JP 5641992B2 JP 2011061209 A JP2011061209 A JP 2011061209A JP 2011061209 A JP2011061209 A JP 2011061209A JP 5641992 B2 JP5641992 B2 JP 5641992B2
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quenching
steel
hardness
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藤松 威史
威史 藤松
盛彦 中崎
盛彦 中崎
康弘 松本
康弘 松本
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Sanyo Special Steel Co Ltd
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/001Ferrous alloys, e.g. steel alloys containing N
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/002Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/06Ferrous alloys, e.g. steel alloys containing aluminium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum

Description

本発明は、例えば、自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達部品として用いられる機械構造用鋼に関し、特に熱処理変形の小さい機械構造用鋼に関する。   The present invention relates to a machine structural steel used as a power transmission component such as a gear and a shaft used in automobiles and industrial machines, for example, and more particularly to a machine structural steel having a small heat treatment deformation.

焼入れ等の熱処理によって発生する鋼材の変形(以下「熱処理変形」という。)は、その変形を矯正するために製造工程数が増えたり、矯正しきれない場合には部品不良率が増加したり、あるいは駆動系部品として組み込んだ場合に変形に起因して騒音や振動を発生させるといった悪影響がある。したがって、熱処理変形をできる限り小さく抑えることが実用上非常に重要な課題となっている。   Deformation of steel materials caused by heat treatment such as quenching (hereinafter referred to as “heat treatment deformation”) increases the number of manufacturing processes in order to correct the deformation, or the part defect rate increases if it cannot be corrected, Alternatively, when incorporated as a drive system component, there is an adverse effect of generating noise and vibration due to deformation. Therefore, it is a very important problem in practice to keep the heat treatment deformation as small as possible.

従来、この熱処理変形は鋼材以外にも部品形状、熱処理前工程の影響、焼入油などの冷媒の物性値、冷却の不均一性といった多数の要因に影響を受けると考えられ、それらを適正化することによる熱処理変形の軽減が図られている。例えば、材料対策として、焼き入れ鋼材の芯部に軟質のフェライト相を析出させて熱処理歪みを軽減する方法が提案されている(例えば、特許文献1参照。)。   Conventionally, this heat treatment deformation is considered to be affected by many factors besides the steel material, such as part shape, influence of pre-heat treatment processes, physical properties of refrigerants such as quenching oil, and non-uniform cooling. By doing so, the deformation of the heat treatment is reduced. For example, as a material countermeasure, a method has been proposed in which a soft ferrite phase is precipitated in the core of a hardened steel material to reduce heat treatment strain (see, for example, Patent Document 1).

また、冷却方法からのアプローチとして、従来型の油焼入れではなく加圧ガス冷却を利用する方法が提案されている(例えば、特許文献2参照。)。また、熱伝達率を促進あるいは低減する手段を用いて被冷却物の均一冷却化を図る方法が提案されている(例えば、特許文献3参照。)。   As an approach from the cooling method, a method using pressurized gas cooling instead of conventional oil quenching has been proposed (see, for example, Patent Document 2). In addition, a method for achieving uniform cooling of an object to be cooled using means for promoting or reducing the heat transfer coefficient has been proposed (for example, see Patent Document 3).

なお、特許文献3において、熱伝達率を促進する手段は、冷却が遅れる部位に設けられた冷却を促進する被膜材または冷却が遅れる部位の周りに形成された冷却剤の対流によるものであり、熱伝達率の低減手段は、冷却が進行しやすい部位を覆うグラスウールまたは断熱被膜材によるとされている。   In Patent Document 3, the means for promoting the heat transfer coefficient is due to the convection of the coating material that promotes cooling provided in the portion where cooling is delayed or the coolant formed around the portion where cooling is delayed, The means for reducing the heat transfer rate is said to be glass wool or a heat insulating coating material covering a portion where cooling is likely to proceed.

しかしながら、上記で提案されている従来の方法において、特許文献1の技術では、部品内部に強度の低い軟質相が導入されることや、特許文献2の技術では、熱処理炉そのものを変更しなければならないことや、特許文献3の技術では、個々の熱処理部品に対する処理が必要になることなどで、必ずしも汎用的な手段ではなかった。   However, in the conventional method proposed above, the technique of Patent Document 1 introduces a soft phase having a low strength inside the component, or the technique of Patent Document 2 does not change the heat treatment furnace itself. However, the technique disclosed in Patent Document 3 is not necessarily a general-purpose means because it requires processing of individual heat-treated parts.

一方、本願の発明者らは、フェライトのような軟質層に頼らずに十分な鋼材強度を確保した上で、油焼入れなどの一般的な手法の下で部品の冷却が不均一となる場合でも、熱処理変形が小さく抑えられる鋼に関して鋭意研究を行った。その結果、鋼の化学成分、マルテンサイト変態開始温度(Ms点)、ジョミニー式一端焼入法により測定される焼入性を適切に制御することによって熱処理変形が小さく抑えられることを終に見出し、本発明に至った。   On the other hand, the inventors of the present application ensure sufficient steel strength without relying on a soft layer such as ferrite, and even when cooling of parts is not uniform under a general technique such as oil quenching. And earnestly researched on steel that can keep heat treatment deformation small. As a result, finally found that the heat treatment deformation can be suppressed small by appropriately controlling the chemical composition of the steel, the martensite transformation start temperature (Ms point), and the hardenability measured by the Jomini type one-end quenching method, The present invention has been reached.

特開1997−111408号公報JP 1997-111408 A 特開2008−121064号公報JP 2008-121064 A 特開2010−174289号公報JP 2010-174289 A

本発明が解決しようとする課題は、自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達用の部品として用いられる機械構造用鋼からなる熱処理変形の少ない鋼材を提供することである。   The problem to be solved by the present invention is to provide a steel material with less heat treatment deformation made of mechanical structural steel used as power transmission parts such as gears and shafts used in automobiles and industrial machines.

上記の課題を解決するための本発明の手段は、請求項1の手段では、質量%で、C:0.16〜0.35%、Si:0.10〜1.50%、Mn:0.10〜1.20%、P:0.030%以下、S:0.030%以下、Cr:1.30〜2.50%、Cu:0.30%以下、Al:0.008〜0.800%、O:0.0030%以下、N:0.0020〜0.0300%を含有し、残部Feおよび不可避不純物からなる機械構造用鋼で、該鋼からなる鋼材のマルテンサイト変態開始温度(Ms点)が460℃以下であり、該鋼材についてジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5および距離9mmにおける硬さのJ9を用いて、下記の式(1)により算出の(J9/J1.5)の値が0.68〜0.97の範囲にあり、さらに距離1.5mmにおける硬さのJ1.5、および距離11mmにおける硬さのJ11を用いて下記の式(2)により算出の(J11/J1.5)の値が0.63〜0.94の範囲にあることを特徴とする熱処理変形の小さい機械構造用鋼材である。
ただし、
(J9/J1.5)=(ジョミニー式一端焼入法により測定される焼入端からの距離9mmにおける硬さ)÷(ジョミニー式一端焼入法により測定される焼入端からの距離1.5mmの硬さ)・・・式(1)
(J11/J1.5)=(ジョミニー式一端焼入法により測定される焼入端からの距離11mmにおける硬さ)÷(ジョミニー式一端焼入法により測定される焼入端からの距離1.5mmにおける硬さ)・・・式(2)
The means of the present invention for solving the above problem is that in the means of claim 1, C: 0.16 to 0.35%, Si: 0.10 to 1.50%, Mn: 0 in mass%. .10 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 1.30 to 2.50%, Cu: 0.30% or less, Al: 0.008 to 0 .800%, O: 0.0030% or less, N: 0.0020 to 0.0300%, and a structural structural steel composed of the remaining Fe and inevitable impurities, and the martensitic transformation start temperature of the steel material composed of the steel The (Ms point) is 460 ° C. or less, and the steel material is measured by the Jominy-type one-end quenching method, the hardness J1.5 at a distance 1.5 mm from the quenching end of the steel material and the hardness J9 at a distance 9 mm. (J9 / J1.5) calculated by the following equation (1) using The value is in the range of 0.68 to 0.97, and further calculated by the following equation (2) using J1.5 of hardness at a distance of 1.5 mm and J11 of hardness at a distance of 11 mm (J11 / J1.5) is a steel for machine structural use with small heat treatment deformation, characterized in that it is in the range of 0.63 to 0.94.
However,
(J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (distance from the quenching end measured by the Jominy type one-end quenching method. 5mm hardness) ... Formula (1)
(J11 / J1.5) = (hardness at a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (distance from the quenching end measured by the Jominy type one-end quenching method. (Hardness at 5 mm) (2)

請求項2の手段では、質量%で、C:0.16〜0.35%、Si:0.10〜1.50%、Mn:0.10〜1.20%、P:0.030%以下、S:0.030%以下、Cr:1.30〜2.50%、Cu:0.30%以下、Al:0.008〜0.800%、O:0.0030%以下、N:0.0020〜0.0300%を含有し、さらにNi:0.20〜3.00%、Mo:0.05〜0.50%の1種または2種を含有し、残部Feおよび不可避不純物からなる機械構造用鋼からなる鋼材であり、さらに、この鋼材のマルテンサイト変態開始温度(Ms点)が460℃以下であり、この鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5および距離9mmにおける硬さのJ9を用いて上記の式(1)により算出の(J9/J1.5)の値が0.68〜0.97の範囲にあり、さらに、距離1.5mmにおける硬さのJ1.5および距離11mmにおける硬さのJ11を用いて、上記の式(2)により算出の(J11/J1.5)の値が0.63〜0.94の範囲にあることを特徴とする熱処理変形の小さい機械構造用鋼材である。   In the means of claim 2, in mass%, C: 0.16-0.35%, Si: 0.10-1.50%, Mn: 0.10-1.20%, P: 0.030% Hereinafter, S: 0.030% or less, Cr: 1.30 to 2.50%, Cu: 0.30% or less, Al: 0.008 to 0.800%, O: 0.0030% or less, N: 0.0020 to 0.0300%, Ni: 0.20 to 3.00%, Mo: 0.05 to 0.50% of one or two, containing the balance Fe and inevitable impurities Further, the steel material is made of mechanical structural steel, and the martensite transformation start temperature (Ms point) of the steel material is 460 ° C. or less, and the steel material is hardened as measured by the Jomini-type one-time quenching method. Hardness J1.5 at distance 1.5mm from end and at distance 9mm The value of (J9 / J1.5) calculated by the above equation (1) using J9 of the thickness is in the range of 0.68 to 0.97, and further, the hardness of J1.5 at the distance of 1.5 mm And J11 of hardness at a distance of 11 mm, the value of (J11 / J1.5) calculated by the above equation (2) is in the range of 0.63 to 0.94. It is a small steel for machine structural use.

請求項3の手段では、質量%で、C:0.16〜0.35%、Si:0.10〜1.50%、Mn:0.10〜1.20%、P:0.030%以下、S:0.030%以下、Cr:1.30〜2.50%、Cu:0.30%以下、Al:0.008〜0.800%、O:0.0030%以下、N:0.0020〜0.0300%を含有し、さらにTi:0.020〜0.200%、Nb:0.02〜0.20%のうち少なくとも一種以上を含有し、残部Feおよび不可避不純物からなる機械構造用鋼からなる鋼材であり、さらに、この鋼材のマルテンサイト変態開始温度(Ms点)が460℃以下であり、この鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5および距離9mmにおける硬さのJ9を用いて上記の式(1)により算出の(J9/J1.5)の値が0.68〜0.97の範囲にあり、さらに、距離1.5mmにおける硬さのJ1.5および距離11mmにおける硬さのJ11を用いて、上記の式(2)により算出の(J11/J1.5)の値が0.63〜0.94の範囲にあることを特徴とする熱処理変形の小さい機械構造用鋼材である。   In the means of claim 3, in mass%, C: 0.16-0.35%, Si: 0.10-1.50%, Mn: 0.10-1.20%, P: 0.030% Hereinafter, S: 0.030% or less, Cr: 1.30 to 2.50%, Cu: 0.30% or less, Al: 0.008 to 0.800%, O: 0.0030% or less, N: It contains 0.0020 to 0.0300%, further contains at least one of Ti: 0.020 to 0.200% and Nb: 0.02 to 0.20%, and consists of the balance Fe and inevitable impurities. It is a steel material made of steel for machine structural use. Further, the martensitic transformation start temperature (Ms point) of this steel material is 460 ° C. or less, and the hardened end of the steel material measured by the Jomini type one-end quenching method for this steel material. J1.5 of hardness and distance 9 at a distance of 1.5 mm from The value of (J9 / J1.5) calculated by the above equation (1) using J9 of hardness at m is in the range of 0.68 to 0.97, and further the hardness at distance of 1.5 mm Using J1.5 and J11 of hardness at a distance of 11 mm, the value of (J11 / J1.5) calculated by the above equation (2) is in the range of 0.63 to 0.94. It is a steel for machine structural use with small heat treatment deformation.

請求項4の手段では、質量%で、C:0.16〜0.35%、Si:0.10〜1.50%、Mn:0.10〜1.20%、P:0.030%以下、S:0.030%以下、Cr:1.30〜2.50%、Cu:0.30%以下、Al:0.008〜0.800%、O:0.0030%以下、N:0.0020〜0.0300%を含有し、さらにNi:0.20〜3.00%、Mo:0.05〜0.50%のうち少なくとも1種以上を含有し、さらにTi:0.020〜0.200%、Nb:0.02〜0.20%の1種または2種を含有し、残部Feおよび不可避不純物からなる機械構造用鋼からなる鋼材であり、さらに、この鋼材のマルテンサイト変態開始温度(Ms点)が460℃以下であり、この鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5および距離9mmにおける硬さのJ9を用いて上記の式(1)により算出の(J9/J1.5)の値が0.68〜0.97の範囲にあり、さらに、距離1.5mmにおける硬さのJ1.5および距離11mmにおける硬さのJ11を用いて、上記の式(2)により算出の(J11/J1.5)の値が0.63〜0.94の範囲にあることを特徴とする熱処理変形の小さい機械構造用鋼材である。   In the means of claim 4, by mass%, C: 0.16-0.35%, Si: 0.10-1.50%, Mn: 0.10-1.20%, P: 0.030% Hereinafter, S: 0.030% or less, Cr: 1.30 to 2.50%, Cu: 0.30% or less, Al: 0.008 to 0.800%, O: 0.0030% or less, N: 0.0020 to 0.0300%, further containing at least one of Ni: 0.20 to 3.00%, Mo: 0.05 to 0.50%, and further Ti: 0.020 ˜0.200%, Nb: 0.02 to 0.20% of one or two kinds of steel, a steel material made of steel for mechanical structure consisting of Fe and unavoidable impurities, and further martensite of this steel material The transformation start temperature (Ms point) is 460 ° C. or less, and Jominy type one-end firing of this steel material (J9 / J1.5) calculated by the above equation (1) using J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel material measured by the method and J9 of the hardness at a distance of 9 mm. Is in the range of 0.68 to 0.97, and is calculated by the above equation (2) using J1.5 of hardness at a distance of 1.5 mm and J11 of hardness at a distance of 11 mm ( J11 / J1.5) is a steel for machine structural use with small heat treatment deformation, characterized in that the value is in the range of 0.63 to 0.94.

上記の各請求項の手段における成分の限定理由について、以下に説明する。なお、各成分元素の%は質量%を示す。   The reasons for limiting the components in the means of the above claims will be described below. In addition,% of each component element shows the mass%.

C:0.16〜0.35%
Cは、機械構造用部品として鋼材の焼入焼戻し後の強度もしくは浸炭焼入焼戻し後の芯部強度を確保するために必要な元素であるとともに、熱処理変形を小さくするために所定の範囲に調整する必要がある。その範囲は0.16%未満では強度を確保できず、0.35%を超えると熱処理による変形が大きくなり過ぎる。そこでCは0.16〜0.35%とし、望ましくは0.20〜0.30%、より望ましくは0.22〜0.27%とする。
C: 0.16-0.35%
C is an element necessary for ensuring the strength after quenching and tempering of steel or the strength of the core after carburizing, quenching and tempering as machine structural parts, and is adjusted to a predetermined range in order to reduce heat treatment deformation. There is a need to. If the range is less than 0.16%, the strength cannot be secured, and if it exceeds 0.35%, deformation due to heat treatment becomes too large. Therefore, C is 0.16 to 0.35%, preferably 0.20 to 0.30%, more preferably 0.22 to 0.27%.

Si:0.10〜1.50%
Siは、脱酸に必要な元素であるとともに、鋼に必要な強度、焼入性を付与するために有効な元素である。しかし、Siが0.10%未満ではその効果が得られず、1.50%を超えると機械加工性を低下させる。そこでSiは0.10〜1.50%とし、望ましくは0.20〜1.00%とする。
Si: 0.10 to 1.50%
Si is an element necessary for deoxidation and is an effective element for imparting necessary strength and hardenability to steel. However, if Si is less than 0.10%, the effect cannot be obtained, and if it exceeds 1.50%, the machinability is lowered. Therefore, Si is 0.10 to 1.50%, preferably 0.20 to 1.00%.

Mn:0.10〜1.20%
Mnは、焼入性を確保するために必要な元素である。しかし、Mnが0.10%未満では焼入性への効果は十分に得られず、1.20%を超えると機械加工性を低下させる。そこでMnは0.10〜1.20%とし、望ましくは0.20〜0.80%、より望ましくは0.20〜0.55%とする。
Mn: 0.10 to 1.20%
Mn is an element necessary for ensuring hardenability. However, if Mn is less than 0.10%, a sufficient effect on hardenability cannot be obtained, and if it exceeds 1.20%, the machinability is lowered. Therefore, Mn is 0.10 to 1.20%, preferably 0.20 to 0.80%, and more preferably 0.20 to 0.55%.

P:0.030%以下
Pは、スクラップから含有される不可避な元素であるが、粒界に偏析して衝撃強度や曲げ強度などの特性を低下させる。そこでPは0.030%以下とする。
P: 0.030% or less P is an unavoidable element contained in scrap, but segregates at the grain boundary and lowers properties such as impact strength and bending strength. Therefore, P is set to 0.030% or less.

S:0.030%以下
Sは、被削性を向上させる元素であるが、非金属介在物であるMnSを生成して横方向の靱性および疲労強度を低下する。そこでSは0.030%以下とする。
S: 0.030% or less S is an element that improves machinability, but produces MnS that is a non-metallic inclusion and lowers the toughness and fatigue strength in the transverse direction. Therefore, S is set to 0.030% or less.

Ni:0.20〜3.00%
Niは、焼入性および靱性を向上させる元素であり、その効果を得るためには0.20%以上の添加が必要である。しかし、Niは3.00%を超えて含有すると加工性を著しく低下させ、かつ、コストアップとなる。そこでNiは3.00%以下とする。
Ni: 0.20 to 3.00%
Ni is an element that improves hardenability and toughness, and in order to obtain the effect, addition of 0.20% or more is necessary. However, if Ni is contained over 3.00%, the workability is remarkably lowered and the cost is increased. Therefore, Ni is set to 3.00% or less.

Cr:1.30〜2.50%
Crは、焼入性を確保するために必要な元素である。しかし、Crが1.30%未満では焼入性への効果は十分に得られず、2.50%を超えると浸炭を阻害し、また機械加工性も低下する。そこでCrは1.30〜2.50%とし、望ましくは1.50〜2.25%とする。
Cr: 1.30 to 2.50%
Cr is an element necessary for ensuring hardenability. However, if Cr is less than 1.30%, a sufficient effect on hardenability cannot be obtained. Therefore, Cr is 1.30 to 2.50%, preferably 1.50 to 2.25%.

Mo:0.05〜0.50%
Moは、焼入性および靱性を向上させる元素であり、その効果を得るには0.05%以上の添加が必要である。しかし、Moは0.50%を超えて含有すると加工性を低下させる。そこで、Moは0.05〜0.50%とする。
Mo: 0.05 to 0.50%
Mo is an element that improves hardenability and toughness, and 0.05% or more of addition is necessary to obtain the effect. However, if Mo exceeds 0.50%, workability is reduced. Therefore, Mo is set to 0.05 to 0.50%.

Cu:0.30%以下
Cuは、スクラップから含有される不可避な元素であるが、時効性を有し、強度を上昇させる効果がある。しかし、Cuは0.30%を超えると熱間加工性を低下する。そこで、Cuは0.30%以下とする。
Cu: 0.30% or less Cu is an inevitable element contained from scrap, but has aging properties and an effect of increasing strength. However, when Cu exceeds 0.30%, the hot workability decreases. Therefore, Cu is made 0.30% or less.

Al:0.010〜0.800%
Alは、脱酸材として使用される元素であり、また後述のようにNと結合してAlNとして析出して結晶粒粗大化抑制効果をもたらす。この効果を得るため、Alは0.010%以上の添加が必要である。一方、Alを0.800%を超えて添加すると大型のアルミナ系介在物を形成し、疲労特性および加工性を低下する。そこで、Alは0.010〜0.800%とし、望ましくは0.014〜0.600%とする。
Al: 0.010-0.800%
Al is an element used as a deoxidizing material, and also binds to N and precipitates as AlN as will be described later, thereby bringing about an effect of suppressing grain coarsening. In order to obtain this effect, Al needs to be added in an amount of 0.010% or more. On the other hand, when Al is added in excess of 0.800%, large alumina inclusions are formed, and fatigue characteristics and workability are deteriorated. Therefore, Al is made 0.010 to 0.800%, preferably 0.014 to 0.600%.

・O:0.0030%以下
Oは、鋼中に不可避的に含有される元素である。しかし、Oが0.0030%を超えて含有されると酸化物の増加による加工性や疲労強度の低下を招く。そこでOは0.0030%以下とし、望ましくは0.0020%以下とする。
O: 0.0030% or less O is an element inevitably contained in steel. However, if O exceeds 0.0030%, workability and fatigue strength are reduced due to an increase in oxide. Therefore, O is set to 0.0030% or less, preferably 0.0020% or less.

N:0.0020〜0.0300%
Nは、鋼中でAlNやNb窒化物として微細析出し、結晶粒粗大化を防止する効果をもたらし、その効果を得るために0.0020%以上添加する必要がある。しかし、0.0300%を超えると窒化物が増加し、疲労強度や加工性が低下する。そこで、Nは0.0020〜0.0300%とし、望ましくは0.0020〜0.0200%とする。ただし、特にTiを0.020%以上含有する鋼においては、TiNの過剰生成による疲労強度の低下を避けるため、Nは0.0020〜0.0100%とする。
N: 0.0020 to 0.0300%
N precipitates finely as AlN or Nb nitride in the steel and brings about an effect of preventing coarsening of crystal grains, and 0.0020% or more needs to be added to obtain the effect. However, if it exceeds 0.0300%, nitrides increase, and fatigue strength and workability decrease. Therefore, N is 0.0020 to 0.0300%, preferably 0.0020 to 0.0200%. However, especially in steel containing 0.020% or more of Ti, N is made 0.0020 to 0.0100% in order to avoid a decrease in fatigue strength due to excessive TiN formation.

Ti:0.020〜0.200%
Tiは、鋼中のCと結び付いて炭化物を微細に形成し、結晶粒粗大化を防止する効果をもたらすが、その効果を得る場合には、Tiを0.020%以上を添加する必要がある。一方、0.200%を超える添加は、機械加工性を損なうため、上限は0.200%とする。
Ti: 0.020 to 0.200%
Ti combines with C in steel to form carbides finely and brings about the effect of preventing crystal grain coarsening. To obtain this effect, it is necessary to add 0.020% or more of Ti. . On the other hand, since addition exceeding 0.200% impairs machinability, the upper limit is made 0.200%.

Nb:0.02〜0.20%
Nbは、炭化物あるいは窒化物を形成し、結晶粒粗大化防止効果をもたらす。特に鋼中に微細に分散したナノオーダーサイズのNbCまたはNb(C,N)が結晶粒の成長を抑制する。Nbが0.02%未満では、その効果は得られず、0.20%を超えると析出物の量が過剰となり加工性を低下する。そこで、Nbは0.02〜0.20%、望ましくは0.02〜0.12%とする。
Nb: 0.02 to 0.20%
Nb forms carbides or nitrides, and has an effect of preventing crystal grain coarsening. In particular, nano-order sized NbC or Nb (C, N) finely dispersed in steel suppresses the growth of crystal grains. If Nb is less than 0.02%, the effect cannot be obtained, and if it exceeds 0.20%, the amount of precipitates becomes excessive and the workability deteriorates. Therefore, Nb is 0.02 to 0.20%, preferably 0.02 to 0.12%.

Ms点:460℃以下
本発明の手段における、鋼材の熱処理変形を小さくするために、マルテンサイト変態開始温度(Ms点)を460℃以下に規制する必要がある。Ms点を460℃以下に規制することで熱処理変形を小さくできる理由は、焼入れした際に、部品の冷却がたとい不均一であっても、冷媒の冷却性能が高い温度域でマルテンサイト変態が起こることを回避でき、その結果、マルテンサイト変態の時期が部品の部位によって大きくずれることが抑制できるからである。そこでMs点を460℃以下に規制するが、望ましくはMs点は450℃以下に規制する。なお、この場合の熱処理変形とは、軸状の部品の曲がりやギヤの歯の倒れやねじれのことである。
Ms point: 460 ° C. or lower In order to reduce the heat treatment deformation of the steel material in the means of the present invention, it is necessary to regulate the martensitic transformation start temperature (Ms point) to 460 ° C. or lower. The reason why heat treatment deformation can be reduced by restricting the Ms point to 460 ° C. or lower is that martensite transformation occurs in a temperature range where the cooling performance of the refrigerant is high even if the parts are not evenly cooled when quenched. This is because it is possible to avoid this, and as a result, it is possible to prevent the time of martensitic transformation from being greatly shifted depending on the parts. Therefore, the Ms point is restricted to 460 ° C. or lower, but preferably the Ms point is restricted to 450 ° C. or lower. In this case, the heat treatment deformation refers to bending of a shaft-like component or falling or twisting of gear teeth.

(J9/J1.5)の値:0.68〜0.97、(J11/J1.5)の値:0.63〜0.94
鋼材のジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5と、距離9mmにおける硬さのJ9と、距離11mmにおける硬さのJ11とから算出される(J9/J1.5)の値を0.68〜0.97に規制し、(J11/J1.5)の値を0.63〜0.94に規制する理由は、この範囲とすることで鋼材の熱処理変形が小さく抑えられるからである。ここで言う熱処理変形とは、部品の焼入れ前後における寸法(長さ、径、厚み)の変化のことである。なお、ジョミニー焼入性の適切な制御によって、熱処理変形が抑制されるメカニズムについては、未だ解明できていないが、鋼材の焼入性が低すぎても、また、高すぎても熱処理変形が大きくなることが発明者らによって実験的に明らかとなっている。
(J9 / J1.5) value: 0.68 to 0.97, (J11 / J1.5) value: 0.63 to 0.94
From the J1.5 hardness at a distance of 1.5 mm from the quenching end of the steel material measured by the Jominy-type one-end quenching method of the steel material, the J9 hardness at a distance of 9 mm, and the J11 hardness at a distance of 11 mm The reason why the calculated value of (J9 / J1.5) is regulated to 0.68 to 0.97 and the value of (J11 / J1.5) is regulated to 0.63 to 0.94 is This is because the heat treatment deformation of the steel material can be suppressed small. The heat treatment deformation referred to here is a change in dimensions (length, diameter, thickness) before and after quenching of the part. The mechanism by which heat treatment deformation is suppressed by appropriate control of Jominy hardenability has not yet been elucidated, but even if the hardenability of steel is too low or too high, heat treatment deformation is large. It has become experimentally clear by the inventors.

本発明の手段の鋼成分の限定およびMs点の限定およびジョミニー式一端焼入法により測定される焼入性の限定により、鋼材を部品に加工した後、部品を硬化させるための焼入れや浸炭焼入れを行った場合の熱処理変形を小さくすることができ、この結果、本発明は、部品の歩留の向上、部品の矯正工程の簡略化や廃止、あるいは騒音および振動対策のためのギヤの歯面研削の省略が可能になるといった有益な効果を奏することができる。   Quenching and carburizing and quenching to harden the parts after processing the steel into parts by limiting the steel component and Ms point of the means of the present invention and by limiting the hardenability as measured by the Jomini-type one-end quenching method As a result, the present invention can improve the yield of parts, simplify or eliminate the correction process of parts, or gear tooth surfaces for noise and vibration countermeasures. There is a beneficial effect that grinding can be omitted.

本発明を実施するための形態について、以下に表を参照して説明する。
自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達用の部品として用いられる機械構造用鋼として、表1に示す本発明例のNo.1〜23の成分組成と残部Feおよび不可避不純物からなる機械構造用鋼を真空誘導溶解炉にて溶製し、100kgの鋼塊を得た。
EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated with reference to a table | surface below.
As steel for machine structure used as power transmission parts such as gears and shafts used in automobiles and industrial machines, No. 1 of the present invention shown in Table 1 is shown. Machine structural steel consisting of 1 to 23 component compositions, the balance Fe and inevitable impurities was melted in a vacuum induction melting furnace to obtain a 100 kg steel ingot.

上記の本発明例と同様に、自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達用の部品として用いられる機械構造用鋼として、表2に示す比較例のNo.1〜16の成分組成と残部Feと不可避不純物からなる鋼を真空誘導溶解炉にて溶製し、100kgの鋼塊を得た。   As in the above-described examples of the present invention, as a steel for machine structural use used as a power transmission component such as a gear or a shaft used in automobiles, industrial machines, etc., the comparative example No. Steel consisting of 1 to 16 component compositions, the balance Fe and inevitable impurities was melted in a vacuum induction melting furnace to obtain 100 kg of steel ingot.

先ず、これらの本発明例および比較例の鋼塊を1250℃で5時間加熱した後、直径32mmの棒鋼に鍛伸した。次に、900℃で1.5時間加熱保持した後に空冷する焼ならしを行った。続いて、直径32mmの棒鋼から直径20mm、長さ200mmの試験片を作製し、その試験片の側面に深さ5mm、幅8mm、長さ200mmの溝加工を施した。この溝加工によって焼き入れた際に、試験片内の部位によって冷却速度に大きく差がつくようにした。また、溝加工後の試験片の長さを測定した。続いて、これらの試験片を930℃で1時間加熱した後、炉内で850℃まで降温し、さらに1時間保持した後、60℃の焼入油中へ焼き入れた。焼入れ後、十分に冷えた試験片について、試験片の曲りおよび長さを測定した。   First, the steel ingots of these inventive examples and comparative examples were heated at 1250 ° C. for 5 hours, and then forged into a steel bar having a diameter of 32 mm. Next, normalizing was performed by heating and holding at 900 ° C. for 1.5 hours and then air cooling. Subsequently, a test piece having a diameter of 20 mm and a length of 200 mm was produced from a steel bar having a diameter of 32 mm, and a groove having a depth of 5 mm, a width of 8 mm, and a length of 200 mm was applied to the side surface of the test piece. When quenching was performed by this groove processing, the cooling rate was varied greatly depending on the portion in the test piece. Moreover, the length of the test piece after groove processing was measured. Then, after heating these test pieces at 930 ° C. for 1 hour, the temperature was lowered to 850 ° C. in the furnace, and further kept for 1 hour, and then quenched into quenching oil at 60 ° C. About the test piece fully cooled after hardening, the bending and length of the test piece were measured.

なお、熱処理後の曲りについては、試験片の両端をVブロックで保持し、試験片を一周回転させたときの試験片の中央部の円周上の最大変位と最小変位をダイヤルゲージで測定し、最大変位と最小変位の差を2で割ることにより求めた。この測定の際、試験片の円周上に存在する溝の底の部分の変位は無視するものとした。また、寸法変化の指標として、熱処理前後の試験片の長さの差を求め、その絶対値を評価した。   For bending after heat treatment, hold both ends of the test piece with V block, and measure the maximum and minimum displacement on the circumference of the center of the test piece with a dial gauge when the test piece is rotated once. The difference between the maximum displacement and the minimum displacement was obtained by dividing by 2. In this measurement, the displacement of the bottom portion of the groove existing on the circumference of the test piece was ignored. Further, as an index of dimensional change, a difference in length of the test piece before and after the heat treatment was obtained, and the absolute value was evaluated.

また、上記の焼ならし後の直径32mmの棒鋼から直径3mmで長さ10mmの試験片を割り出し、鋼材のマルテンサイト変態開始温度であるMs点を、全自動変態記録測定装置を用いて測定した。ここで言うMs点は部品の冷却過程を想定した条件下で測定されるものであり、本実施の形態においては、上記した直径20mmの溝付き試験片の油温60℃の場合の油焼入れを想定して、焼入れ時の冷却速度を30℃/sとして測定している。鋼材のジョミニー式一端焼入法による焼入性の測定については、上記の鍛伸した直径32mmの棒鋼から試験片を作製し、JIS G 0561に規定される「鋼の焼入性試験方法(一端焼入方法)」に準じた条件の下で試験を行って評価した。   Further, a test piece having a diameter of 3 mm and a length of 10 mm was determined from the above-mentioned normalized steel bar having a diameter of 32 mm, and the Ms point, which is the martensitic transformation start temperature of the steel material, was measured using a fully automatic transformation recording measuring device. . The Ms point mentioned here is measured under the condition that the cooling process of the part is assumed. In the present embodiment, oil quenching in the case of the above-described grooved test piece with a diameter of 20 mm at an oil temperature of 60 ° C. Assuming that the cooling rate during quenching is 30 ° C./s. For the measurement of the hardenability of the steel material by the Jominy type one-end quenching method, a test piece is prepared from the above-described forged steel bar having a diameter of 32 mm, and the “steel hardenability test method (one end) is defined in JIS G 0561. The test was conducted under the conditions according to the quenching method) and evaluated.

表3に本発明例の測定されたMs点、ジョミニー式一端焼入法で測定した焼入端からの、距離1.5mmにおける硬さのJ1.5、距離9mmにおける硬さのJ9および距離11mmにおける硬さのJ11のそれぞれの値、また、求めた(J9/J1.5)の値および(J11/J1.5)の値を示す。さらに、上記試験片の焼入れ後に評価した曲り(mm)、および、熱処理前後の試験片の長さの差の絶対値(mm)を示す。発明例のNo.1〜23からなる鋼材では、表3に示すように、マルテンサイト変態開始温度すなわちMs点が372〜442℃の範囲にあり、この鋼材の(J9/J1.5)の下記に示す式(1)の値が0.70〜0.95の範囲にあり、(J11/J1.5)の下記に示す式(2)の値が0.65〜0.90の範囲にあり、熱処理後の曲りは0.10〜0.36mmで、熱処理前後の試験片の長さの差の絶対値は0.01〜0.20mmであった。
ただし、
(J9/J1.5)=(ジョミニー式一端焼入法により測定される焼入れ端からの距離9mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入れ端からの距離1.5mmの硬さ)……(1)
(J11/J1.5)=(ジョミニー式一端焼入法により測定される焼入れ端からの距離11mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入れ端からの距離1.5mmの硬さ)……(2)
Table 3 shows the measured Ms point of the example of the present invention, J1.5 of hardness at a distance of 1.5 mm, J9 of hardness at a distance of 9 mm, and a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method. The respective values of the hardness J11, and the obtained values (J9 / J1.5) and (J11 / J1.5) are shown. Furthermore, the bending (mm) evaluated after quenching the test piece and the absolute value (mm) of the difference in length of the test piece before and after the heat treatment are shown. Invention Example No. In the steel material consisting of 1 to 23, as shown in Table 3, the martensite transformation start temperature, that is, the Ms point is in the range of 372 to 442 ° C., and (J9 / J1.5) of this steel material is represented by the following formula (1 ) Is in the range of 0.70 to 0.95, the value of the formula (2) shown below in (J11 / J1.5) is in the range of 0.65 to 0.90, and the bend after heat treatment Was 0.10 to 0.36 mm, and the absolute value of the difference in length of the test piece before and after the heat treatment was 0.01 to 0.20 mm.
However,
(J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (1)
(J11 / J1.5) = (hardness at a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (a distance of 1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (2)

同様に、表4に比較例の鋼の測定されたMs点、ジョミニー式一端焼入法により測定した焼入端からの距離1.5mmにおける硬さのJ1.5、距離9mmにおける硬さのJ9および距離11mmにおける硬さのJ11であるジョミニー焼入性、また、求めた(J9/J1.5)の値および(J11/J1.5)の値を示す。さらに、上記試験片の焼入れ後の曲り(mm)、および、熱処理前後の試験片の長さの差の絶対値(mm)を示す。   Similarly, Table 4 shows the measured Ms point of the steel of the comparative example, J1.5 of the hardness at a distance of 1.5 mm from the quenching end measured by the Jomini type one-end quenching method, and J9 of the hardness at a distance of 9 mm. And Jominy hardenability which is J11 of hardness at a distance of 11 mm, and the obtained values of (J9 / J1.5) and (J11 / J1.5) are shown. Furthermore, the bending (mm) after quenching of the test piece and the absolute value (mm) of the difference in length of the test piece before and after the heat treatment are shown.

上記の発明例のNo.1〜23では、鋼材のFeおよびNi、Moを除く不可避不純物を除いた組成範囲を表1に示すものとし、Ms点を460℃以下の372〜442℃とし、ジョミニー式一端焼入法により測定される焼入性を適切に制御して、式(1)から計算される(J9/J1.5)の値を0.70〜0.95の範囲、式(2)から計算される(J11/J1.5)の値を0.65〜0.90の範囲とすることによって、熱処理後の試験片の曲りを0.10〜0.36mmの小さな範囲に、さらに熱処理前後の試験片の長さの差の絶対値を0.01〜0.20mmの小さな範囲に抑えることができた。   No. of the above invention example. 1 to 23, the composition range excluding unavoidable impurities excluding Fe, Ni, and Mo of steel materials is shown in Table 1, and the Ms point is set to 372 to 442 ° C. of 460 ° C. or less, and measured by the Jomini type one-end quenching method By appropriately controlling the hardenability to be performed, the value of (J9 / J1.5) calculated from the equation (1) is calculated from the range of 0.70 to 0.95 and from the equation (2) (J11 /J1.5) in the range of 0.65 to 0.90, the bending of the specimen after the heat treatment is reduced to a small range of 0.10 to 0.36 mm, and the length of the specimen before and after the heat treatment is further increased. The absolute value of the difference in thickness could be suppressed to a small range of 0.01 to 0.20 mm.

これに対し、上記の比較例のNo.1〜16の、鋼材のFeおよびNi、Moを除く不可避不純物を除いた組成範囲を表2に示すものでは、No.2、No.16の2例を除く、残りの14例は本発明の組成範囲から外れるものであった。これらNo.1〜16の比較例の鋼のうち、測定されたMs点が460℃を超える10例は、熱処理後の試験片の曲りが0.49〜0.76mmであり、発明例の鋼に比べ大きい。また、これらNo.1〜16の比較鋼のうち、ジョミニー式一端焼入法によって測定した硬さから式(1)、および式(2)により求まる(J9/J1.5)が0.68〜0.97の範囲外であり、および(J11/J1.5)の値が0.63〜0.94の範囲外である15例は、熱処理前後の試験片の長さの差の絶対値が0.27〜0.45mmとなり、発明例の鋼に比べて大きい。したがって、比較例のうちで熱処理後の試験片の曲りおよび熱処理前後の試験片の長さの差の絶対値が共に本発明例の鋼と同等のものは1例も無かった。   On the other hand, No. of the above comparative example. In Table 2, the composition range excluding inevitable impurities excluding Fe, Ni, and Mo of steel materials 1 to 16 is shown in Table 2. 2, no. The remaining 14 cases, excluding 16 2 cases, were out of the composition range of the present invention. These No. Among the steels of Comparative Examples 1 to 16, 10 cases where the measured Ms point exceeds 460 ° C. are 0.49 to 0.76 mm in bending of the test piece after the heat treatment, which is larger than the steels of the inventive examples. . In addition, these No. Among the comparative steels 1 to 16, the range (J9 / J1.5) determined by the formula (1) and the formula (2) is 0.68 to 0.97 from the hardness measured by the Jomini type one-end quenching method. 15 examples in which the value of (J11 / J1.5) is outside the range of 0.63 to 0.94, the absolute value of the difference in length of the test piece before and after the heat treatment is 0.27 to 0 .45 mm, which is larger than the steel of the invention example. Therefore, among the comparative examples, there was no example in which the absolute value of the difference between the bending of the test piece after the heat treatment and the length of the test piece before and after the heat treatment was equivalent to that of the steel of the present invention.

測定したMs点が請求の範囲を外れる比較例のNo.1〜3、5〜7、9、10、14、15と比較して、Ms点が請求の範囲を満足する本発明例のNo.1〜23は、熱処理後の試験片の曲りが小さく、熱処理変形が抑制されている。また、(J9/J1.5)の値および(J11/J1.5)の値が請求の範囲を外れる比較例のNo.1、3〜16に比べて、(J9/J1.5)の値および(J11/J1.5)の値が請求の範囲を満足する発明例のNo.1〜23は、熱処理前後の試験片の長さの差の絶対値が小さく、熱処理変形が抑えられている。なお、本実施の形態では、浸炭焼入れでは無く、焼入れによって熱処理変形を評価しているが、浸炭焼入れした場合でも、本請求項を満たす鋼材の熱処理変形が小さいことを確認している。なお、本発明例の鋼材は焼入れ後に焼戻しを施してから使用される。   No. of the comparative example in which the measured Ms point is outside the scope of the claims. 1 to 3, 5 to 7, 9, 10, 14, and 15 in which the Ms point satisfies the claims. In Nos. 1 to 23, the bending of the test piece after the heat treatment is small, and the heat treatment deformation is suppressed. In addition, the values of (J9 / J1.5) and (J11 / J1.5) are out of the scope of claims. Compared with 1 and 3 to 16, the values of (J9 / J1.5) and (J11 / J1.5) satisfy the scope of claims. In Nos. 1 to 23, the absolute value of the difference in length of the test pieces before and after the heat treatment is small, and the heat treatment deformation is suppressed. In this embodiment, heat treatment deformation is evaluated not by carburizing and quenching but by quenching. However, even when carburized and quenched, it is confirmed that the heat treatment deformation of the steel material satisfying the present claim is small. The steel material of the present invention is used after tempering after quenching.

以上から、本発明における鋼成分の限定およびマルテンサイト変態開始温度であるMs点の限定およびジョミニー式一端焼入法により測定される焼入性の限定により、鋼材を部品に加工した後、部品を硬化させるための焼入れや浸炭焼入れを行った場合の熱処理変形を小さくすることができる。このような本発明による鋼材は、自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達用の部品に適用しうる鋼材である。   From the above, according to the present invention, the steel material is processed into a part by the limitation of the steel component, the Ms point which is the martensitic transformation start temperature, and the limitation of the hardenability measured by the Jominy one-side quenching method. Heat treatment deformation when hardening for hardening or carburizing and quenching can be reduced. Such a steel material according to the present invention is a steel material applicable to power transmission parts such as gears and shafts used in automobiles and industrial machines.

Claims (4)

質量%で、C:0.16〜0.35%、Si:0.10〜1.50%、Mn:0.10〜1.20%、P:0.030%以下、S:0.030%以下、Cr:1.30〜2.50%、Cu:0.30%以下、Al:0.008〜0.800%、O:0.0030%以下、N:0.0020〜0.0300%を含有し、残部Feおよび不可避不純物からなる機械構造用鋼であり、該鋼からなる鋼材のマルテンサイト変態開始温度(Ms点)が460℃以下であり、該鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5および距離9mmにおける硬さのJ9を用いて、下記の式(1)によって算出した(J9/J1.5)の値が0.68〜0.97の範囲にあり、さらに距離1.5mmにおける硬さのJ1.5および距離11mmにおける硬さのJ11を用いて、下記の式(2)によって算出した(J11/J1.5)の値が0.63〜0.94の範囲にあることを特徴とする熱処理変形の小さい機械構造用鋼材。
ただし、
(J9/J1.5)=(ジョミニー式一端焼入法により測定される焼入端からの距離9mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入端からの距離1.5mmの硬さ)……式(1)
(J11/J1.5)=(ジョミニー式一端焼入法により測定される焼入端からの距離11mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入端からの距離1.5mmの硬さ)……式(2)
In mass%, C: 0.16-0.35%, Si: 0.10-1.50%, Mn: 0.10-1.20%, P: 0.030% or less, S: 0.030 %: Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008-0.800%, O: 0.0030% or less, N: 0.0020-0.0300 %, The balance is Fe and inevitable impurities, and the steel material is martensitic transformation start temperature (Ms point) of 460 ° C. or less. Using the following formula (1), J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel material measured by the method and J9 of the hardness at a distance of 9 mm was calculated (J9 / J1.5 ) In the range of 0.68 to 0.97, and the distance 1. The value of (J11 / J1.5) calculated by the following equation (2) using J1.5 of hardness at mm and J11 of hardness at distance 11 mm is in the range of 0.63 to 0.94. A machine structural steel material having a small heat treatment deformation.
However,
(J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (distance from the quenching end measured by the Jominy type one-end quenching method. (Hardness of 5mm) …… Formula (1)
(J11 / J1.5) = (hardness of a distance of 11 mm from the quenching end measured by the Jomini-type one-end quenching method) ÷ (distance from the quenching end measured by the Jomini-type one-end quenching method. (Hardness of 5mm) …… Formula (2)
質量%で、C:0.16〜0.35%、Si:0.10〜1.50%、Mn:0.10〜1.20%、P:0.030%以下、S:0.030%以下、Cr:1.30〜2.50%、Cu:0.30%以下、Al:0.008〜0.800%、O:0.0030%以下、N:0.0020〜0.0300%を含有し、さらにNi:0.20〜3.00%、Mo:0.05〜0.50%の1種または2種を含有し、残部Feおよび不可避不純物からなる機械構造用鋼であり、該鋼からなる鋼材のマルテンサイト変態開始温度(Ms点)が460℃以下であり、該鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5および距離9mmにおける硬さのJ9を用いて、下記の式(1)によって算出した(J9/J1.5)の値が0.68〜0.97の範囲にあり、さらに距離1.5mmにおける硬さのJ1.5および距離11mmにおける硬さのJ11を用いて、下記の式(2)によって算出した(J11/J1.5)の値が0.63〜0.94の範囲にあることを特徴とする熱処理変形の小さい機械構造用鋼材。
ただし、
(J9/J1.5)=(ジョミニー式一端焼入法により測定される焼入端からの距離9mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入端からの距離1.5mmの硬さ)……(1)
(J11/J1.5)=(ジョミニー式一端焼入法により測定される焼入端からの距離11mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入端からの距離1.5mmの硬さ)……(2)
In mass%, C: 0.16-0.35%, Si: 0.10-1.50%, Mn: 0.10-1.20%, P: 0.030% or less, S: 0.030 %: Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008-0.800%, O: 0.0030% or less, N: 0.0020-0.0300 Is a steel for machine structural use that further contains one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%, the balance being Fe and inevitable impurities. The steel material made of the steel has a martensite transformation start temperature (Ms point) of 460 ° C. or less, and the steel material has a hardness at a distance of 1.5 mm from the quenching end of the steel material measured by the Jominy one-end quenching method. The following formula (1) using J1.5 of the thickness and J9 of the hardness at a distance of 9 mm Therefore, the calculated value (J9 / J1.5) is in the range of 0.68 to 0.97, and further using the hardness J1.5 at the distance 1.5 mm and the hardness J11 at the distance 11 mm, (J11 / J1.5) calculated by the equation (2) in the range of 0.63 to 0.94, a steel material for mechanical structure having a small heat treatment deformation.
However,
(J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (distance from the quenching end measured by the Jominy type one-end quenching method. (Hardness of 5mm) …… (1)
(J11 / J1.5) = (hardness of a distance of 11 mm from the quenching end measured by the Jomini-type one-end quenching method) ÷ (distance from the quenching end measured by the Jomini-type one-end quenching method. (Hardness of 5mm) …… (2)
質量%で、C:0.16〜0.35%、Si:0.10〜1.50%、Mn:0.10〜1.20%、P:0.030%以下、S:0.030%以下、Cr:1.30〜2.50%、Cu:0.30%以下、Al:0.008〜0.800%、O:0.0030%以下、N:0.0020〜0.0300%を含有し、さらにTi:0.020〜0.200%、Nb:0.02〜0.20%の1種または2種を含有し、残部Feおよび不可避不純物からなる機械構造用鋼であり、該鋼からなる鋼材のマルテンサイト変態開始温度(Ms点)が460℃以下であり、該鋼材についてジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5および距離9mmにおける硬さのJ9を用いて、下記の式(1)によって算出した(J9/J1.5)の値が0.68〜0.97の範囲にあり、さらに距離1.5mmにおける硬さのJ1.5および距離11mmにおける硬さのJ11を用いて、下記の式(2)によって算出した(J11/J1.5)の値が0.63〜0.94の範囲にあることを特徴とする熱処理変形の小さい機械構造用鋼材。
ただし、
(J9/J1.5)=(ジョミニー式一端焼入法により測定される焼入れ端からの距離9mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入れ端からの距離1.5mmの硬さ)……(1)
(J11/J1.5)=(ジョミニー式一端焼入法により測定される焼入れ端からの距離11mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入れ端からの距離1.5mmの硬さ)……(2)
In mass%, C: 0.16-0.35%, Si: 0.10-1.50%, Mn: 0.10-1.20%, P: 0.030% or less, S: 0.030 %: Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008-0.800%, O: 0.0030% or less, N: 0.0020-0.0300 Is a steel for machine structural use that contains 1 or 2 types of Ti: 0.020-0.200%, Nb: 0.02-0.20%, and the balance Fe and inevitable impurities. , The martensitic transformation start temperature (Ms point) of the steel material made of the steel is 460 ° C. or less, and the steel material has a hardness at a distance of 1.5 mm from the quenching end of the steel material measured by the Jomini type one-end quenching method. J1.5 and hardness of 9 at a distance of 9 mm, the following formula (1 The value of (J9 / J1.5) calculated by the above is in the range of 0.68 to 0.97, and further using the hardness J1.5 at a distance of 1.5 mm and the hardness J11 at a distance of 11 mm, (J11 / J1.5) calculated by the equation (2) in the range of 0.63 to 0.94, a steel material for mechanical structure having a small heat treatment deformation.
However,
(J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (1)
(J11 / J1.5) = (hardness at a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (a distance of 1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (2)
質量%で、C:0.16〜0.35%、Si:0.10〜1.50%、Mn:0.10〜1.20%、P:0.030%以下、S:0.030%以下、Cr:1.30〜2.50%、Cu:0.30%以下、Al:0.008〜0.800%、O:0.0030%以下、N:0.0020〜0.0300%
を含有し、さらにNi:0.20〜3.00%、Mo:0.05〜0.50%の1種または2種を含有し、さらにTi:0.020〜0.200%、Nb:0.02〜0.20%の1種または2種を含有し、残部Feおよび不可避不純物からなる機械構造用鋼であり、該鋼からなる鋼材のマルテンサイト変態開始温度(Ms点)が460℃以下であり、該鋼材についてジョミニー式一端焼入法により測定される鋼材の焼入端からの距離1.5mmにおける硬さのJ1.5および距離9mmにおける硬さのJ9を用いて、下記の式(1)によって算出した(J9/J1.5)の値が0.68〜0.97の範囲にあり、さらに距離1.5mmにおける硬さのJ1.5および距離11mmにおける硬さのJ11を用いて、下記の式(2)によって算出した(J11/J1.5)の値が0.63〜0.94の範囲にあることを特徴とする熱処理変形の小さい機械構造用鋼材。
ただし、
(J9/J1.5)=(ジョミニー式一端焼入法により測定される焼入れ端からの距離9mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入れ端からの距離1.5mmの硬さ)……(1)
(J11/J1.5)=(ジョミニー式一端焼入法により測定される焼入れ端からの距離11mmの硬さ)÷(ジョミニー式一端焼入法により測定される焼入れ端からの距離1.5mmの硬さ)……(2)
In mass%, C: 0.16-0.35%, Si: 0.10-1.50%, Mn: 0.10-1.20%, P: 0.030% or less, S: 0.030 %: Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008-0.800%, O: 0.0030% or less, N: 0.0020-0.0300 %
In addition, Ni: 0.20 to 3.00%, Mo: 0.05 to 0.50%, or one or two of Ti: 0.020 to 0.200%, Nb: It is a steel for machine structural use containing 0.02 to 0.20% of 1 type or 2 types and the balance being Fe and inevitable impurities, and the martensitic transformation start temperature (Ms point) of the steel material made of the steel is 460 ° C. The following formula is used, using J1.5 of the hardness at a distance of 1.5 mm and J9 of the hardness at a distance of 9 mm from the quenching end of the steel material measured by the Jominy one-side quenching method for the steel material. The value of (J9 / J1.5) calculated by (1) is in the range of 0.68 to 0.97, and further, J1.5 of hardness at a distance of 1.5 mm and J11 of hardness at a distance of 11 mm are used. Calculated by the following formula (2) Small mechanical structural steel of heat treatment deformation, characterized in that the value of the (J11 / J1.5) is in the range of 0.63 to 0.94.
However,
(J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (1)
(J11 / J1.5) = (hardness at a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (a distance of 1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (2)
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