JP4665327B2 - Method for producing B-containing high carbon steel with excellent cold workability in hot work - Google Patents
Method for producing B-containing high carbon steel with excellent cold workability in hot work Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、自動車の動力伝達部材、軸受け、工具等に使用される機械構造用の高炭素鋼に係り、とくに熱間加工ままでセメンタイトの球状化が促進され、優れた冷間加工性を具えた高炭素鋼に関するものである。
【０００２】
【従来の技術】
高炭素鋼を素材とした各種の機械構造部材は、高炭素鋼の圧延素材を、棒状または板状に熱間圧延したのち、これを鍛造、引き抜き、切削、切断等の冷間加工により所望の製品形状に加工して製造される。このとき、熱間圧延後に形成される金属組織は硬質かつ板状のセメンタイト相からなるパーライト主体の組織であるために、熱間圧延のままでは冷間加工時の加工性が極めて悪い。そのため、かかる構造部材の製造方法においては、従来から、熱間圧延後に球状化熱処理を施し、板状であったセメンタイトを球状化することにより、鋼材を軟質化して加工性を向上させるのが一般的であった。
【０００３】
【発明が解決しようとする課題】
ところで、従来から行われてきた球状化熱処理は、板状のセメンタイト相を有する鋼を、亜共析鋼ではγ／（γ＋α）すなわちＡc３変態点、過共析鋼ではγ／（γ＋セメンタイト）すなわちＡcm変態点の温度近くまで加熱し、セメンタイト相をわずかに残して固溶させ、その後Ａ１変態点直下に保持する球状化熱処理により、残存したセメンタイトを核として新たなセメンタイトを析出、球状化させるものであった。この方法では、Ａc３変態点またはＡcm変態点の温度域における保持が高すぎた場合にはセメンタイトが完全に固溶してしまい、その後のＡ１変態点直下でのセメンタイト相の析出が遅滞することとなる。このような場合、球状化には長時間を必要とするだけでなく、長時間保持のために炭化物が粗大化しやすく、製品特性の劣化を招いてしまう。このように、熱間加工後に球状化熱処理の工程を別途必要とする従来の製造方法では、十分な球状化を達成するには温度などの緻密な管理が必要であるだけでなく、熱処理時間が長いために生産性の低下や製造コストの上昇を招くという問題があった。
【０００４】
そこで、本発明は、従来技術が抱えている上記問題に鑑み、熱間加工（主として、熱間圧延）のままでセメンタイトを球状化させて軟質化を図ることにより、球状化熱処理を施さなくとも、優れた冷間加工性が得られる高炭素鋼の製造方法を提供することを目的とする。
【０００５】
【課題を解決するための手段】
発明者らは、上掲の課題の解決に向けて、鋭意、実験・検討を重ねている中で、Ｂ（ボロン）の化合物である Fe２Ｂあるいは Fe３（Ｃ，Ｂ）が、セメンタイト相の核生成サイトとして極めて優れた能力を有すること、また、かかるＢ化合物を核生成サイトとして有効に析出させるには、鋼組成としてＢだけでなく、AlやＮなどを適正範囲で含有させるとともに、析出前の熱間加工とその後の冷却を適正な条件で行うことがことが重要であることを知見した。
【０００６】
本発明は、このような知見に基づいてなされたものであり、Ｃ：０．６０〜１．１０ｍａｓｓ％、Ｓｉ：２．０ｍａｓｓ％以下、Ｍｎ：２．０ｍａｓｓ％以下、Ａｌ：０．１０ｍａｓｓ％以下、Ｎ：０．００５０ｍａｓｓ％以下、Ｂ：０．００５〜０．２００ｍａｓｓ％を含有し、残部がＦｅおよび不可避的不純物からなる成分組成の鋼素材を、１０００〜９００℃の温度範囲で少なくとも１パスは１パス当たりの加工率を２５％以上とする加工、あるいは前記温度範囲における累積加工率を６０％以上とする加工、の少なくとも一方の加工条件を満たして熱間加工し、次いで、８００〜６５０℃間の冷却速度を３０℃／ｈ以下として冷却することを特徴とする、熱間加工ままでの冷間加工性に優れる含Ｂ高炭素鋼の製造方法である。また、本発明は、上記発明において、鋼素材の成分組成がさらに、Ｃｒ：２．０ｍａｓｓ％以下、Ｍｏ：１．０ｍａｓｓ％以下、Ｖ：０．５ｍａｓｓ％以下、Ｎｂ：０．５ｍａｓｓ％以下から選ばれる１種または２種以上を含有することを特徴とする、熱間加工ままでの冷間加工性に優れる含Ｂ高炭素鋼の製造方法である。
【０００７】
【発明の実施の形態】
本発明において、Ｂ化合物である Fe２Ｂがセメンタイト相の核生成サイトとして機能するのは、冶金的に次のような現象によるものであると考えられる。
すなわち、鋼中におけるＢ含有量がγ相における固溶限以上であると析出 Fe２Ｂが、また0.15mass％を超えると共晶 Fe２Ｂが出現する。そして、これらの Fe２Ｂは高炭素鋼の球状化熱処理温度に相当する 900℃以下では未固溶のままで存在する。したがって、球状化熱処理温度に相当するＡc３変態点またはＡcm変態点の近傍に加熱する際に、未固溶セメンタイトが極めて少なくなる高い温度条件であっても、その後のＡ１変態点直下の保持において Fe２Ｂがセメンタイトの核生成サイトとして作用し、析出、球状化が遅滞なく進行することとなる。また、未固溶セメンタイト相が適量残存する従来の適正な球状化処理に相当する温度条件では、Ａ１変態点直下の保持において未固溶セメンタイトとともに Fe２Ｂもセメンタイトの核生成サイトとして作用するため、従来の製造方法よりも球状化が速やかに進行することとなる。
【０００８】
このようなセメンタイトの核生成サイトとして作用する Fe２Ｂを鋼中に析出させるためには、γ相における固溶限以上、すなわち0.005 mass％以上のＢ含有量が必要である。また、 Fe２Ｂの効果を十分に発揮させるためには、AlおよびＮの含有量をAl：0.10mass％以下、Ｎ：0.0050mass％以下にまで十分低下させておく必要がある。
さらに、本発明のように、Ｂを多量に含有する高炭素鋼においては、 Fe２Ｂ以外に、 Fe３（Ｃ、Ｂ）がより高温でも存在できるようになる。具体的には、鋼の製造時における通常の熱間加工温度域で Fe３（Ｃ、Ｂ）が析出しうる。
【０００９】
本発明では、上述したように、通常の熱間加工温度域で析出しうる２種類の析出物を、熱間加工後の共析変態時のセメンタイト析出核として活用し、熱間加工のままで、球状化組織を得るものである。しかし、通常の熱間加工条件では、これら２種類の析出物が、選択的にオーステナイト粒界上に析出、または、ラメラー状に析出しやすいため、その後の球状化組織に十分に寄与しにくい。
そこで、発明者らは、熱間加工条件を適正化すれば、セメンタイトに先行して析出するこれら析出物の析出／分散状態を良好な状態に制御できて、球状化に有効に寄与させることができることを見いだした。すなわち、これら析出物の析出温度範囲である1000〜900 ℃において、１パス当たりの加工率が２５％以上のパスを少なくとも１パス以上とし、さらに熱間加工終了後の 800〜650 ℃間の冷却速度を３０℃／ｈ以下とすることが有効であることがわかった。
【００１０】
このようにして、加工率２５％以上／パスの高加工を付与することにより、析出物の分散、組織の再結晶による後続の析出サイトの分散が図られる。ここに、加工率を定める温度範囲を1000〜900 ℃としたのは、この温度域がγ相とFe２BまたはFe３Cとの共存域であるからである。この温度範囲での加工率が２５％に満たないと、Fe２BまたはFe３Cが粗大化したり、偏在した組織となる。また、冷却速度を定める温度範囲を 800〜650 ℃としたのは、母相に固溶しているC が析出またはフェライトへの変態に伴いFe３Cが析出するからであり、この温度範囲での冷却速度を３０℃／ｈ以下としたのは、３０℃／ｈを超える速い冷却速度になるとFe３Cが球状化せずラメラー状形態を呈するからである。
【００１１】
同様の機構から、1000〜900 ℃における累積加工率を６０％以上とし、さらに熱間加工終了後の 800〜650 ℃間の冷却速度を３０℃／ｈ以下とすることも有効であることがわかった。そしてまた、発明者らは、1000〜900 ℃において、１パス当たりの加工率を２５％以上とするパスを少なくとも１パス以上とし、かつ累積加工率を６０％以上とすることによっても、同様な効果が得られることを確認した。
なお、本発明で言う加工率とは断面減少率を言い、累積加工率とは素材と最終パス後の断面積から求まる断面減少率を意味する。
【００１２】
次に、鋼組成の限定理由について説明する。
Ｃ：0.60〜1.10mass％
Ｃ量は、セメンタイト相を形成し、強度を確保するために、0.60mass％以上は必要である。しかし、過剰に含有するとセメンタイト量が過剰になり、靱性、延性の低下が著しくなるので、1.10mass％を上限とする。なお、好ましいＣ含有量は0.65超え〜1.10mass％である。
【００１３】
Si：2.0 mass％以下
Siは、固溶強化あるいは焼入れ性の増大を通じて、強度を確保するのに重要な元素である。また、脱酸材としても必要な元素である。しかし、過剰に含有すると、靱性や延性の劣化が著しくなるため、2.0 mass％を上限とする。なお、好ましいSi含有量は0.2 〜2.0 mass％である。
【００１４】
Mn：2.0 mass％以下
Mnは、焼入れ性の増大効果を通じて、強度を確保するのに重要な元素である。
しかし過剰に含有すると、靱性や延性の劣化が著しくなるため、2.0 mass％を上限とする。なお、好ましいMn含有量は0.5 超え〜2.0 mass％である。
【００１５】
Al：0.10 mass ％以下
Alは、Ｂによる球状化の改善効果を阻害する元素である。このため、Al含有量は0.10 mass ％以下に制限する必要がある。
【００１６】
Ｎ：0.0050mass％以下
Ｎは、Alと同様に、Ｂによる球状化の改善効果を阻害する元素である。このため、Ｎ含有量は0.0050mass％以下に制限する必要がある。
【００１７】
Ｂ：0.005 〜0.200 mass％
Ｂは、本発明において、とくに重要な元素であり、Ｂの化合物である Fe２Ｂまたは Fe３（Ｃ、Ｂ）が共析変態時のセメンタイト相の核生成サイトとして作用し、球状化の促進に寄与する。こうした効果を発現させるには、0.005 mass％以上のＢを含有させることが必要である。しかし、過剰に含有させても、その効果が飽和するだけでなく、かえって Fe２Ｂによる硬さ上昇を招くようになるので、上限を0.200 mass％とする。なお、好ましいＢ含有量は0.005 〜0.150 mass％である。
【００１８】
本発明では、上述した各成分に加えて、さらに、Cr、Mo、ＶおよびNbから選ばれる少なくとも１種または２種以上を含有させることができる。
これらの元素は、いずれもセメンタイト相に固溶し、セメンタイト相の析出、球状化を促進させる元素である。しかし、過剰に含有させても、その効果は飽和するのみならず、鋼コストの増大、焼入れ性の増大を招いてしまう。したがって、これらの元素は、Cr：2.0 mass％以下、Mo：1.0 mass％以下、Ｖ：0.5 mass％以下、Nb：0.5 mass％以下の範囲で含有させるものとする。
【００１９】
【実施例】
次に本発明を実施例に基づいて説明する。
鋼素材の成分が表１に示すような、本発明範囲にある鋼 No.１〜７、Ｂ含有量が本発明範囲に満たない従来鋼 No.８を、1150℃に加熱後、表２に示す条件で２０ｍｍφの丸棒に熱間加工た。
得られた各試験材の1/4 部位置で、熱間加工後の硬さをビッカース硬度Hvにて測定（測定荷重 98N、 5点の平均値）し、熱間加工ままで球状化の促進によってもたらされる、軟質化による加工性向上効果を調査した。Ｈｖ値が２３０以下であれば、その後に行われる、伸線、鍛造等の冷間加工に十分耐えられるので、この範囲にあれば球状化による軟質化が良好であると判断した。その評価結果を、併せて表２に示す。表２において、Ｈｖ≦２３０のものを○印で示した。
【００２０】
【表１】
【表２】
実験Ｎｏ．１〜３、６〜１１の発明例では、熱間加工ままで、十分に低い硬さが得られており、本発明の効果が明瞭にあらわれた。一方、加工条件、冷却条件のいずれかが本発明範囲を逸脱する実験Ｎｏ．４、５の比較例、またＢ量が本発明範囲に満たない実験Ｎｏ．１２の従来例は、いずれも硬さが高く、冷間加工を行うには球状化熱処理が必要であった。
【００２３】
【発明の効果】
以上説明したように、本発明によれば、熱間加工のままで、鋼の軟質化が図られる。したがって、本発明によれば、従来のように、熱間圧延後に再加熱して長時間保持する球状化熱処理を行う必要がなくなり、工程省略、生産性の向上、製品コストの低減が可能になる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high carbon steel for machine structure used for power transmission members, bearings, tools, etc. of automobiles, and particularly, promotes the spheroidization of cementite as it is hot-worked and has excellent cold workability. High carbon steel.
[0002]
[Prior art]
Various machine structural members made of high-carbon steel can be obtained by hot rolling a rolled material of high-carbon steel into a rod or plate shape, and then performing cold processing such as forging, drawing, cutting, cutting, etc. Manufactured by processing into product shape. At this time, since the metal structure formed after hot rolling is a pearlite-based structure composed of a hard and plate-like cementite phase, the workability during cold working is extremely poor with hot rolling. Therefore, in the manufacturing method of such a structural member, conventionally, it has been common to perform spheroidizing heat treatment after hot rolling to spheroidize the cementite that was plate-like, thereby softening the steel material and improving workability. It was the target.
[0003]
[Problems to be solved by the invention]
By the way, the conventional spheroidizing heat treatment is performed by using a steel having a plate-like cementite phase as γ / (γ + α), that is, Ac 3 transformation point in hypoeutectoid steel, or γ / (γ + cementite) in hypereutectoid steel. that was heated to a temperature close to the Acm transformation point, cementite phase is slightly leaving a solid solution, followed by spheroidization heat treatment for holding just below the a 1 transformation point, precipitating new cementite remaining cementite as a nucleus, spheroidized It was something to be made. In this method, when the Ac 3 transformation point or the Acm transformation point is held at a high temperature, the cementite is completely dissolved, and the subsequent precipitation of the cementite phase immediately below the A 1 transformation point is delayed. It will be. In such a case, not only a long time is required for the spheroidization, but also the carbide is likely to be coarsened due to the long-time holding, resulting in deterioration of product characteristics. As described above, in the conventional manufacturing method that requires a separate spheroidizing heat treatment step after hot working, not only precise management such as temperature is necessary to achieve sufficient spheroidization, but also the heat treatment time. Due to the long length, there is a problem that productivity is lowered and manufacturing cost is increased.
[0004]
Therefore, in view of the above-described problems of the prior art, the present invention can be used without spheroidizing heat treatment by spheroidizing cementite while maintaining the hot working (mainly hot rolling) to soften the cementite. An object of the present invention is to provide a method for producing a high carbon steel capable of obtaining excellent cold workability.
[0005]
[Means for Solving the Problems]
Inventors have been diligently experimenting and studying to solve the above-mentioned problems, and Fe 2 B or Fe 3 (C, B), which is a compound of B (boron), is a cementite phase. In order to effectively precipitate such a B compound as a nucleation site, not only B as a steel composition but also Al, N, etc. are contained in an appropriate range. It was found that it is important to perform hot working before precipitation and subsequent cooling under appropriate conditions.
[0006]
This invention is made | formed based on such knowledge, C: 0.60-1.10 mass%, Si: 2.0 mass% or less, Mn: 2.0 mass% or less, Al: 0.10 mass% Hereinafter, a steel material having a component composition containing N: 0.0050 mass% or less, B: 0.005 to 0.200 mass%, with the balance being Fe and unavoidable impurities is at least 1 in a temperature range of 1000 to 900 ° C. The pass is hot-worked so as to satisfy at least one of the processing conditions of processing at a processing rate of 25% or more per pass, or processing at a cumulative processing rate in the temperature range of 60% or more, and then 800- A method for producing a high carbon steel containing B, which is excellent in cold workability in hot working, characterized by cooling at a cooling rate between 650 ° C. and 30 ° C./h or less. Further, in the present invention, the component composition of the steel material further includes Cr: 2.0 mass% or less, Mo: 1.0 mass% or less, V: 0.5 mass% or less, and Nb: 0.5 mass% or less. It characterized the Turkey to contain one or more members selected, a method for producing a free B high carbon steel excellent in cold workability remain hot working.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, Fe 2 B, which is a B compound, functions as a nucleation site of cementite phase due to the following phenomenon metallurgically.
That is, when the B content in the steel is not less than the solid solubility limit in the γ phase, precipitated Fe 2 B appears, and when it exceeds 0.15 mass%, eutectic Fe 2 B appears. These Fe 2 B exist in an undissolved state at 900 ° C. or less corresponding to the spheroidizing heat treatment temperature of high carbon steel. Therefore, when heating near the Ac 3 transformation point or the Acm transformation point corresponding to the spheroidizing heat treatment temperature, even under a high temperature condition in which undissolved cementite is extremely reduced, it is maintained immediately below the A 1 transformation point. In this case, Fe 2 B acts as a nucleation site for cementite, and precipitation and spheroidization proceed without delay. Under the temperature conditions corresponding to the conventional appropriate spheroidizing treatment in which an appropriate amount of undissolved cementite phase remains, Fe 2 B also acts as a nucleation site of cementite together with undissolved cementite in the retention just below the A 1 transformation point. For this reason, the spheroidization proceeds more rapidly than the conventional production method.
[0008]
In order to precipitate such Fe 2 B acting as a nucleation site of cementite in steel, it is necessary to have a B content of not less than the solid solubility limit in the γ phase, that is, 0.005 mass% or more. Moreover, in order to fully exhibit the effect of Fe 2 B, it is necessary to sufficiently reduce the contents of Al and N to Al: 0.10 mass% or less and N: 0.0050 mass% or less.
Further, in the high carbon steel containing a large amount of B as in the present invention, Fe 3 (C, B) can be present at higher temperatures in addition to Fe 2 B. Specifically, Fe 3 (C, B) can be precipitated in a normal hot working temperature range during steel production.
[0009]
In the present invention, as described above, two kinds of precipitates that can be precipitated in a normal hot working temperature range are utilized as cementite precipitation nuclei during eutectoid transformation after hot working, and the hot working remains as it is. A spheroidized structure is obtained. However, under normal hot working conditions, these two types of precipitates are likely to be selectively deposited on the austenite grain boundaries or in a lamellar form, and therefore do not sufficiently contribute to the subsequent spheroidized structure.
Therefore, the inventors can control the precipitation / dispersion state of these precipitates that precipitate prior to cementite to be in a good state by optimizing the hot working conditions, and can contribute to spheroidization effectively. I found what I could do. That is, in the precipitation temperature range of these precipitates, 1000 to 900 ° C, at least one pass with a processing rate of 25% or more per pass is set to at least one pass, and cooling between 800 to 650 ° C after the hot working is completed. It has been found that it is effective to set the speed to 30 ° C./h or less.
[0010]
In this way, by providing a high working rate of 25% or more / pass, it is possible to disperse precipitates and to disperse subsequent precipitation sites by recrystallization of the structure. The reason why the temperature range for determining the processing rate is 1000 to 900 ° C. is that this temperature region is a coexistence region of the γ phase and Fe 2 B or Fe 3 C. When the processing rate in this temperature range is less than 25%, Fe 2 B or Fe 3 C becomes coarse or becomes unevenly distributed. The reason why the temperature range for determining the cooling rate is 800 to 650 ° C. is that Fe 3 C precipitates due to the precipitation of C dissolved in the matrix or transformation to ferrite. The reason why the cooling rate is 30 ° C./h or less is that when the cooling rate exceeds 30 ° C./h, Fe 3 C does not spheroidize and exhibits a lamellar shape.
[0011]
From the same mechanism, it can be seen that it is also effective to set the cumulative processing rate at 1000 to 900 ° C to 60% or more, and further to set the cooling rate between 800 to 650 ° C after hot processing to 30 ° C / h or less. It was. In addition, the inventors of the present invention are similar by setting at least one pass at a processing rate of 25% or more per pass at 1000 to 900 ° C. and at a cumulative processing rate of 60% or more. It was confirmed that an effect was obtained.
In the present invention, the processing rate refers to the cross-section reduction rate, and the cumulative processing rate refers to the cross-section reduction rate obtained from the material and the cross-sectional area after the final pass.
[0012]
Next, the reason for limiting the steel composition will be described.
C: 0.60 to 1.10 mass%
The amount of C is required to be 0.60 mass% or more in order to form a cementite phase and ensure strength. However, if it is contained excessively, the amount of cementite becomes excessive and the toughness and ductility are remarkably lowered. Therefore, the upper limit is 1.10 mass%. The preferable C content is more than 0.65 to 1.10 mass%.
[0013]
Si: 2.0 mass% or less
Si is an important element for securing strength through solid solution strengthening or hardenability increase. Further, it is a necessary element as a deoxidizing material. However, if excessively contained, the toughness and ductility deteriorate significantly, so the upper limit is 2.0 mass%. A preferable Si content is 0.2 to 2.0 mass%.
[0014]
Mn: 2.0 mass% or less
Mn is an important element for securing strength through the effect of increasing hardenability.
However, if excessively contained, the toughness and ductility deteriorate significantly, so 2.0 mass% is the upper limit. A preferable Mn content is more than 0.5 to 2.0 mass%.
[0015]
Al: 0.10 mass% or less
Al is an element that inhibits the effect of improving the spheroidization by B. For this reason, Al content needs to be limited to 0.10 mass% or less.
[0016]
N: 0.0050 mass% or less N, like Al, is an element that inhibits the improvement effect of spheroidization by B. For this reason, N content needs to be limited to 0.0050 mass% or less.
[0017]
B: 0.005 to 0.200 mass%
B is an especially important element in the present invention, and Fe 2 B or Fe 3 (C, B), which is a compound of B, acts as a nucleation site for cementite phase during eutectoid transformation, and promotes spheroidization. Contribute to. In order to exhibit such an effect, it is necessary to contain 0.005 mass% or more of B. However, even if contained excessively, not only the effect is saturated, but also the hardness is increased by Fe 2 B, so the upper limit is made 0.200 mass%. A preferable B content is 0.005 to 0.150 mass%.
[0018]
In the present invention, in addition to the components described above, at least one or more selected from Cr, Mo, V and Nb can be further contained.
All of these elements are elements that dissolve in the cementite phase and promote the precipitation and spheroidization of the cementite phase. However, even if contained excessively, the effect is not only saturated, but also increases the steel cost and hardenability. Therefore, these elements are contained in the ranges of Cr: 2.0 mass% or less, Mo: 1.0 mass% or less, V: 0.5 mass% or less, and Nb: 0.5 mass% or less.
[0019]
【Example】
Next, this invention is demonstrated based on an Example.
Steel Nos. 1 to 7 within the scope of the present invention, as shown in Table 1, and conventional steel No. 8 with a B content less than the scope of the present invention are heated to 1150 ° C and then in Table 2. It was hot-worked into a 20 mmφ round bar under the conditions shown.
Measure the hardness after hot working with Vickers hardness Hv (measured load 98N, average value of 5 points) at the 1/4 part position of each obtained test material, and promote spheroidization with hot working We investigated the effect of improving the workability by softening. If the Hv value is 230 or less, it can sufficiently withstand the subsequent cold working such as wire drawing and forging. Therefore, it was judged that softening by spheroidization was good within this range. The evaluation results are also shown in Table 2. In Table 2, those with Hv ≦ 230 are indicated by ◯.
[0020]
[Table 1]
[Table 2]
Experiment No. In the invention examples 1 to 3 and 6 to 11, sufficiently low hardness was obtained with hot working, and the effects of the present invention were clearly shown. On the other hand, Experiment No. 1 in which either the machining condition or the cooling condition deviates from the scope of the present invention. Comparative Examples 4 and 5 and Experiment No. in which the B amount is less than the scope of the present invention All of the 12 conventional examples had high hardness, and spheroidizing heat treatment was required for cold working.
[0023]
【The invention's effect】
As described above, according to the present invention, the softening of steel can be achieved with hot working. Therefore, according to the present invention, it is not necessary to perform spheroidizing heat treatment that is reheated after hot rolling and held for a long time as in the prior art, and the process can be omitted, productivity can be improved, and product cost can be reduced. .
Claims (2)
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| JP4252837B2 (en) | 2003-04-16 | 2009-04-08 | Ｊｆｅスチール株式会社 | Steel material with excellent rolling fatigue life and method for producing the same |
| JP4609112B2 (en) * | 2004-02-27 | 2011-01-12 | Ｊｆｅスチール株式会社 | Mechanical structural rod parts with excellent fatigue characteristics |
| DE102009010728C5 (en) | 2009-02-26 | 2019-08-14 | Federal-Mogul Burscheid Gmbh | Piston rings and cylinder liners |
| JP5532662B2 (en) * | 2009-04-15 | 2014-06-25 | Ｊｆｅスチール株式会社 | Carbon steel with excellent spheroidization |
| KR20110032555A (en) * | 2009-09-23 | 2011-03-30 | 주식회사 포스코 | High carbon soft wire rod capable of eliminating softening treatment and method for manufaturing the same |
| CN114657471B (en) * | 2022-03-27 | 2022-12-23 | 中天钢铁集团有限公司 | Production method of low-carbon energy-saving wire rod for bridge cable rope with pressure of not less than 2060MPa |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5399026A (en) * | 1977-02-10 | 1978-08-30 | Kawasaki Steel Co | Method of making mediummanddhighh carbon steel heattrolled steel material having fine pearlite structure for use in cementite spheroidizing annealing treatment |
| JPS62199718A (en) * | 1986-02-25 | 1987-09-03 | Nippon Steel Corp | Direct softening method for rolling material of steel for machine structural use |
| JPS62253724A (en) * | 1986-04-25 | 1987-11-05 | Nippon Steel Corp | Production of wire rod for cold forging having granular cementite structure |
| JPH02237588A (en) * | 1989-03-10 | 1990-09-20 | Sankyo Kk | Pinball machine |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5399026A (en) * | 1977-02-10 | 1978-08-30 | Kawasaki Steel Co | Method of making mediummanddhighh carbon steel heattrolled steel material having fine pearlite structure for use in cementite spheroidizing annealing treatment |
| JPS62199718A (en) * | 1986-02-25 | 1987-09-03 | Nippon Steel Corp | Direct softening method for rolling material of steel for machine structural use |
| JPS62253724A (en) * | 1986-04-25 | 1987-11-05 | Nippon Steel Corp | Production of wire rod for cold forging having granular cementite structure |
| JPH02237588A (en) * | 1989-03-10 | 1990-09-20 | Sankyo Kk | Pinball machine |
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