JP2003268438A - Process for refining molten steel - Google Patents
Process for refining molten steelInfo
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- JP2003268438A JP2003268438A JP2002063355A JP2002063355A JP2003268438A JP 2003268438 A JP2003268438 A JP 2003268438A JP 2002063355 A JP2002063355 A JP 2002063355A JP 2002063355 A JP2002063355 A JP 2002063355A JP 2003268438 A JP2003268438 A JP 2003268438A
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- molten steel
- amount
- steel
- hydrogen
- refining
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、溶鋼の精錬方法に
関する技術分野に属し、詳細には、耐水素割れ性に優れ
た鋼を得るために溶鋼の精錬時にＳ（硫黄）源を添加し
て溶鋼中のＳ量を調整する溶鋼の精錬方法に関する技術
分野に属する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field relating to a method for refining molten steel, and more specifically, an S (sulfur) source is added at the time of refining molten steel in order to obtain steel excellent in hydrogen cracking resistance. It belongs to the technical field relating to a method for refining molten steel in which the amount of S in molten steel is adjusted.
【０００２】[0002]
【従来の技術】耐水素割れ性に優れた鋼を得るために、
溶鋼の精錬時にＳ源を添加して溶鋼中のＳ量（Ｓ濃度）
を調整することが行われる。この溶鋼中のＳ量（以下、
[Ｓ]ともいう）をどの程度に調整するかということに
関し、従来は、レードル分析により得られた溶鋼中の水
素量（以下、 [Ｈ] ともいう）の値と [Ｓ] 値と水素割
れ発生の実績データとの関係を材質別に整理し、材質別
の水素割れ感受性に応じて [Ｓ] 量の下限を規制（もし
くは、上下限を規制）する方式が採られていた。また、
まれに機械的性質の確保の点から [Ｓ] 量の上限値が制
約されるものもあるが、この場合には、 [Ｈ] 上限をよ
り厳しく管理するのが通例であった。2. Description of the Related Art In order to obtain steel excellent in hydrogen cracking resistance,
S content in molten steel (S concentration) by adding S source during refining of molten steel
Adjustments are made. The amount of S in this molten steel (hereinafter,
Regarding the extent to which [S] is adjusted, conventionally, the amount of hydrogen in molten steel (hereinafter also referred to as [H]) obtained by ladle analysis, [S] value, and hydrogen cracking A method was adopted in which the relationship with the actual data of generation was organized by material, and the lower limit of the [S] amount was regulated (or the upper and lower limits were regulated) according to the hydrogen cracking susceptibility of each material. Also,
In some rare cases, the upper limit of the [S] amount is restricted from the viewpoint of securing mechanical properties, but in this case, it was customary to manage the [H] upper limit more strictly.
【０００３】例えば、各社で [Ｈ] 分析方法が異なるた
め一概にはいえないが、強度45kgfのものでは、 [Ｈ]
≦2.5ppm、0.008 ％≦ [Ｓ] ≦0.015 ％で決定するとい
ったように、通常は実績に応じて [Ｓ] 量をある範囲に
規定しておき、また、 [Ｈ]はある値以下になるように
真空脱ガス処理時の時間を設定するなどして、それぞれ
を独立のものとして管理するのが通例であった。[0003] For example, it cannot be said unequivocally because each company has different [H] analysis methods, but when the strength is 45 kgf, [H]
Usually, the [S] amount is specified in a certain range according to the actual results, such as ≤2.5 ppm, 0.008% ≤ [S] ≤0.015%, and the [H] is less than a certain value. It was customary to manage each as an independent one by setting the time for the vacuum degassing process.
【０００４】これは、特に大型の鍛鋼品などにおけるこ
とではあり、通常、厚板や棒鋼などでは、水素量を低減
することは実施されているものの、Ｓ源を添加するよう
なことはない。This is particularly true for large-sized forged steel products and the like. Usually, for thick plates and steel bars, although the hydrogen content has been reduced, no S source is added.
【０００５】[0005]
【発明が解決しようとする課題】大型の鍛鋼品において
は、水素割れ防止のためにＳ源添加量を多くして [Ｓ]
量を高くするという対策がよく採られる。しかし、この
場合には、介在物であるＭｎＳが増加し、製品の清浄度
の悪化および機械的性質の悪化を招いている。また、
[Ｈ] 実績値には、ばらつきがあり、外れれば、後工程
での熱処理追加によるコストアップを招き、また、
[Ｈ] が結果的に低いときにも、先に [Ｓ] は調整して
いるので、過剰なＭｎＳの問題がある。In large-sized forged steel products, the S source addition amount is increased to prevent hydrogen cracking [S].
A measure to increase the amount is often taken. However, in this case, MnS, which is an inclusion, increases, resulting in deterioration of cleanliness of the product and deterioration of mechanical properties. Also,
[H] Actual values vary, and if they deviate from each other, heat treatment will be added in a later step, resulting in cost increase.
Even when the [H] is low as a result, there is a problem of excessive MnS because the [S] is adjusted first.
【０００６】本発明は、このような事情に着目してなさ
れたものであって、その目的は、耐水素割れ性に優れた
鋼を得るために溶鋼の精錬時にＳ源を添加して溶鋼中の
Ｓ量を調整するに際し、溶鋼中のＳ量を過不足なく調整
することができる溶鋼の精錬方法を提供しようとするも
のである。The present invention has been made in view of such circumstances, and its purpose is to add an S source during refining of molten steel in order to obtain steel excellent in hydrogen cracking resistance. It is intended to provide a molten steel refining method capable of adjusting the S amount in molten steel without excess or deficiency when adjusting the S amount of.
【０００７】[0007]
【課題を解決するための手段】上記の目的を達成するた
め、本発明に係る溶鋼の精錬方法は、請求項１〜２記載
の溶鋼の精錬方法としており、それは次のような構成と
したものである。In order to achieve the above object, the method for refining molten steel according to the present invention is the method for refining molten steel according to claims 1 and 2, which has the following constitution. Is.
【０００８】即ち、請求項１記載の溶鋼の精錬方法は、
耐水素割れ性に優れた鋼を得るために溶鋼の精錬時にＳ
源を添加して溶鋼中のＳ量を調整する溶鋼の精錬方法で
あって、溶鋼の精錬時に溶鋼中の水素量を測定し、この
水素量の測定値に基づいて溶鋼中へのＳ源の添加量を定
め、このＳ源を添加して溶鋼中のＳ量を調整することを
特徴とする溶鋼の精錬方法である（第１発明）。That is, the method for refining molten steel according to claim 1 is
In order to obtain steel with excellent hydrogen cracking resistance, S is used during the refining of molten steel.
A method for refining molten steel in which a source is added to adjust the amount of S in molten steel, wherein the amount of hydrogen in the molten steel is measured during refining of the molten steel, and the amount of S source in the molten steel is measured based on the measured value of the amount of hydrogen. A method for refining molten steel is characterized in that the amount of addition is determined and the S source is added to adjust the amount of S in the molten steel (first invention).
【０００９】請求項２記載の溶鋼の精錬方法は、前記溶
鋼中のＳ量を下記の式(1) を満たす値に調整する請求項
１記載の溶鋼の精錬方法である（第２発明）。ただし、
下記式(1) において、 [Ｈ] は溶鋼中の水素量の測定値
（ppm)、 [Ｓ] は溶鋼中のＳ量（質量％）、Ａは鋼の常
温における強度（kgf/cm2)である。α、βは定数であっ
て、 [Ｈ] ／Ａ≦0.073 のときは、α＝0.136 、β＝０
であり、 [Ｈ] ／Ａ＞0.073 のときは、α＝0.571 、β
＝−0.032 である。The molten steel refining method according to claim 2 is the method for refining molten steel according to claim 1, wherein the S content in the molten steel is adjusted to a value satisfying the following formula (1) (second invention). However,
In the following formula (1), [H] is the measured amount of hydrogen in molten steel (ppm), [S] is the amount of S in molten steel (mass%), and A is the strength of the steel at room temperature (kgf / cm 2 ). Is. α and β are constants, and when [H] /A≦0.073, α = 0.136, β = 0
And when [H] / A> 0.073, α = 0.571, β
= -0.032.
【００１０】 [Ｓ] ≧（α [Ｈ] ／Ａ）＋β -------- 式(1)[0010] [S] ≧ (α [H] / A) + β -------- Equation (1)
【００１１】ここで、溶鋼中の水素量の単位のppm は、
質量比でのppm すなわち質量百万分率のことである（以
下、同様）。鋼の強度の単位のkgf/cm2 については、１
kgf/cm2 ＝9.80665 ×104 Paである。Here, the unit ppm of the amount of hydrogen in the molten steel is
It is ppm in mass ratio, that is, the mass part per million (hereinafter the same). For steel strength unit kgf / cm 2 , 1
kgf / cm 2 = 9.80665 × 10 4 Pa.
【００１２】[0012]
【発明の実施の形態】本発明は例えば次のような形態で
実施する。溶鋼の精錬時に溶鋼中の水素量を測定し、こ
の水素量の測定値に基づいて溶鋼中へのＳ源の添加量を
定め、このＳ源を添加して溶鋼中のＳ量を調整する。よ
り具体的には、次のようにして行う。BEST MODE FOR CARRYING OUT THE INVENTION The present invention is implemented in the following modes, for example. The amount of hydrogen in the molten steel is measured during refining of the molten steel, the amount of S source added to the molten steel is determined based on the measured value of the amount of hydrogen, and the S source is added to adjust the amount of S in the molten steel. More specifically, it is performed as follows.
【００１３】溶鋼の精錬時に溶鋼中の水素量をオンライ
ン分析にて求める。次に、この水素量の測定値を、溶鋼
中の水素量と溶鋼中のＳ量と鋼の耐水素割れ性との関係
を示す図や表等に照らし合わせ、これにより、耐水素割
れ性に優れた鋼を得ることができるときの溶鋼中のＳ量
の最小値を求める。そして、得ようとする鋼の耐水素割
れ性だけでなく、清浄度および／または機械的性質の点
も考慮して、溶鋼中のＳ量が前記Ｓ量の最小値より少し
高めのＳ量になるように、溶鋼中へのＳ源（単体硫黄ま
たは硫化物）の添加量を定め、この量のＳ源を溶鋼中へ
添加する。The amount of hydrogen in the molten steel at the time of refining the molten steel is determined by online analysis. Next, the measured value of the hydrogen content is compared with the figures and tables showing the relationship between the hydrogen content in the molten steel, the S content in the molten steel, and the hydrogen cracking resistance of the steel. The minimum value of the amount of S in molten steel when an excellent steel can be obtained is obtained. Then, in consideration of not only hydrogen cracking resistance of the steel to be obtained but also cleanliness and / or mechanical properties, the S content in the molten steel should be slightly higher than the minimum value of the S content. The amount of S source (single element sulfur or sulfide) added to the molten steel is determined so that this amount of S source is added to the molten steel.
【００１４】このような形態で本発明が実施される。以
下、本発明について主にその作用効果を説明する。The present invention is implemented in such a form. Hereinafter, the function and effect of the present invention will be mainly described.
【００１５】本発明に係る溶鋼の精錬方法は、前述の如
く、耐水素割れ性に優れた鋼を得るために溶鋼の精錬時
にＳ源を添加して溶鋼中のＳ量を調整する溶鋼の精錬方
法であって、溶鋼の精錬時に溶鋼中の水素量を測定し、
この水素量の測定値に基づいて溶鋼中へのＳ源の添加量
を定め、このＳ源を添加して溶鋼中のＳ量を調整するこ
とを特徴とする溶鋼の精錬方法としている。As described above, the method for refining molten steel according to the present invention is the refining of molten steel in which the S source is added during refining of the molten steel to adjust the amount of S in the molten steel in order to obtain steel excellent in hydrogen cracking resistance. A method for measuring the amount of hydrogen in molten steel during the refining of molten steel,
Based on the measured value of this amount of hydrogen, the amount of S source added to the molten steel is determined, and the amount of S in the molten steel is adjusted by adding this S source to provide a refining method for molten steel.
【００１６】上記方法によれば、溶鋼の精錬時に溶鋼中
の水素量を測定して把握した上で、その水素量に応じて
溶鋼中のＳ量を調整することができる。即ち、耐水素割
れ性に優れた鋼を得ようとするとき、溶鋼中の水素量に
よって最低限必要な溶鋼中のＳ量は相違するので、従来
法のように単に溶鋼中のＳ量の下限を規制（もしくは上
下限を規制）して溶鋼中のＳ量を調整するのでは、溶鋼
中の水素量によって溶鋼中のＳ量が多くなり過ぎ、不必
要にＭｎＳが増加して清浄度等の悪化を招くという不具
合があるが、これに対し、上記方法によれば、溶鋼中の
水素量に応じて溶鋼中のＳ量を的確に調整することがで
きるので、溶鋼中の水素量によって溶鋼中のＳ量が多く
なり過ぎることがないようにすることができ、また、溶
鋼中のＳ量が不足で少な過ぎることがないようにするこ
ともできる。つまり、上記方法によれば、溶鋼中のＳ量
を過不足なく調整することができる。According to the above method, the amount of hydrogen in the molten steel can be measured and grasped during refining of the molten steel, and then the amount of S in the molten steel can be adjusted according to the amount of hydrogen. That is, when a steel having excellent hydrogen cracking resistance is to be obtained, the minimum required amount of S in molten steel differs depending on the amount of hydrogen in the molten steel. (Or the upper and lower limits are regulated) to adjust the S amount in the molten steel, the S amount in the molten steel becomes too large due to the hydrogen amount in the molten steel, and MnS unnecessarily increases to increase the cleanliness. However, according to the above method, the amount of S in molten steel can be accurately adjusted according to the amount of hydrogen in molten steel. It is possible to prevent the amount of S from becoming too large, and also to prevent the amount of S in the molten steel from being too small and too small. That is, according to the above method, the amount of S in molten steel can be adjusted without excess or deficiency.
【００１７】従って、本発明に係る溶鋼の精錬方法によ
れば、耐水素割れ性に優れた鋼を得るために溶鋼の精錬
時にＳ源を添加して溶鋼中のＳ量を調整するに際し、溶
鋼中のＳ量を過不足なく調整することができるようにな
る。Therefore, according to the method for refining molten steel according to the present invention, when the S source is added during refining the molten steel to adjust the amount of S in the molten steel in order to obtain steel having excellent resistance to hydrogen cracking, The amount of S in the inside can be adjusted just enough.
【００１８】本発明に係る溶鋼の精錬方法によれば、こ
のように溶鋼中のＳ量を過不足なく調整することができ
るので、過剰なＳ源添加（すなわち溶鋼中のＳ量を過剰
に高くすること）によるＭｎＳ量の増大などによる清浄
度の悪化や機械的性質の悪化を抑えつつ、耐水素割れ性
に優れた鋼を得ることができるようになる。即ち、得よ
うとする鋼の規格の許せる範囲内で、溶鋼中の水素量に
応じてＳ源添加量（ひいてはＳ源添加後の溶鋼中のＳ
量）をバランスよく決定することができ、それにより溶
鋼中のＳ量の無用な増大による清浄度の悪化や機械的性
質の悪化を抑えつつ、また、溶鋼中のＳ量の不足による
熱処理追加を不要としつつ、耐水素割れ性に優れた鋼を
得ることができるようになる。According to the method for refining molten steel according to the present invention, the amount of S in molten steel can be adjusted in this manner without excess or deficiency, and therefore an excessive amount of S source is added (that is, the amount of S in molten steel is excessively increased. It is possible to obtain a steel excellent in hydrogen cracking resistance while suppressing deterioration of cleanliness and mechanical properties due to increase in MnS content. That is, within the range permitted by the specifications of the steel to be obtained, the S source addition amount (and thus the S content in the molten steel after the S source addition is added depending on the amount of hydrogen in the molten steel).
(Amount) can be determined in a well-balanced manner, thereby suppressing deterioration of cleanliness and mechanical properties due to useless increase of S content in molten steel, and addition of heat treatment due to lack of S content in molten steel. It becomes possible to obtain a steel excellent in hydrogen cracking resistance while making it unnecessary.
【００１９】本発明において、溶鋼の精錬時に溶鋼中の
水素量を測定するに際し、その測定方法については特に
は限定されないが、オンラインにて（溶鋼の精錬中に）
溶鋼中の水素量を迅速に測定することができ、しかも測
定精度に優れている測定方法を採用することが望まし
い。このような測定方法としては、例えば図２に示すよ
うな水素迅速分析方法を挙げることができる。この水素
迅速分析方法はプローブ浸漬法によるものであり、溶鋼
中の水素量の分析の所要時間は約１分である。なお、こ
れに対し、図３に示す溶鋼試料採取法は分析試料をピン
サンプル採取し、それを分析するという方法によるもの
であり、水素量の分析の所要時間は約20分であるので、
好適ではない。In the present invention, when measuring the amount of hydrogen in molten steel during refining of molten steel, the measuring method is not particularly limited, but online (during refining of molten steel).
It is desirable to employ a measuring method that can quickly measure the amount of hydrogen in the molten steel and is excellent in measurement accuracy. As such a measuring method, for example, a rapid hydrogen analysis method as shown in FIG. 2 can be mentioned. This rapid hydrogen analysis method is based on the probe dipping method, and the time required to analyze the amount of hydrogen in the molten steel is about 1 minute. On the other hand, in the molten steel sampling method shown in FIG. 3, a pin sample of the analysis sample is sampled and analyzed, and the time required to analyze the hydrogen amount is about 20 minutes.
Not suitable.
【００２０】溶鋼の精錬時にＳ源を添加して溶鋼中のＳ
量を調整するが、溶鋼の精錬が複数回行われる場合に
は、最後の精錬時が前記Ｓ量の調整をする精錬時とす
る。溶鋼中へ添加するＳ源としては、Ｓ（単体硫黄）ま
たは硫化物が用いられる。この硫化物としては、その種
類は特には限定されず、種々のものを用いることがで
き、例えば通常ＦｅＳが用いられる。During the refining of the molten steel, the S source is added to add S in the molten steel.
Although the amount is adjusted, when the molten steel is refined a plurality of times, the final refining time is the refining time for adjusting the S amount. As the S source added to the molten steel, S (single sulfur) or sulfide is used. The type of sulfide is not particularly limited, and various types can be used, for example, FeS is usually used.
【００２１】[0021]
【実施例】本発明の実施例及び比較例を以下説明する。
なお、本発明はこの実施例に限定されるものではない。EXAMPLES Examples and comparative examples of the present invention will be described below.
The present invention is not limited to this embodiment.
【００２２】溶鋼の精錬時の溶鋼中の水素量（ [Ｈ] ）
と、溶鋼中のＳ量（ [Ｓ] ）と、この溶鋼の精錬後に所
定の工程を経て得られた鋼についての水素割れ感受性と
の関係を調べた。この結果から、鋼の常温における強度
と [Ｓ] 別の [Ｈ] の水素割れ限界値（限界 [Ｈ] ）を
求めた。即ち、水素割れ感受性調査において水素割れが
発生しやすい場合の [Ｈ] と水素割れが発生しにくい場
合の [Ｈ] との境界の[Ｈ] （それ以上の [Ｈ] では水
素割れが発生しやすく、それ未満の [Ｈ] では水素割れ
が発生しにくい [Ｈ] ）を求めた。Hydrogen content in molten steel during refining of molten steel ([H])
Then, the relationship between the S content ([S]) in the molten steel and the hydrogen cracking susceptibility of the steel obtained through a predetermined process after refining the molten steel was investigated. From this result, the strength of the steel at room temperature and the hydrogen cracking limit value (limit [H]) for each [S] were determined. That is, in the hydrogen cracking susceptibility investigation, [H] at the boundary between [H] when hydrogen cracking is likely to occur and [H] when hydrogen cracking is less likely (at higher [H], hydrogen cracking occurs. It was easy to obtain, and [H] less than that was less likely to cause hydrogen cracking.
【００２３】このとき、溶鋼の精錬後の所定の工程とし
ては、精錬後の溶鋼を下注ぎ造塊法により鋼塊とし、そ
の後、予熱→鍛練→熱処理の工程を経て種々の製品（半
製品）を得る工程とした。At this time, as a predetermined step after refining the molten steel, the molten steel after refining is made into a steel ingot by a downward pouring ingot method, and thereafter, various processes (semi-finished products) are passed through steps of preheating → forging → heat treatment. Was obtained.
【００２４】水素割れ感受性調査は、次のような方法に
より行った。すなわち、各強度別に種々の [Ｈ] 、
[Ｓ] 値のものを同一の鍛練→熱処理にて半製品とし、
その後の超音波探傷（ＵＴ）にて割れの有無を確認し、
１００％合格の限界点を [Ｈ] 、[Ｓ] 別の割れの限界
点とした。なお、このような方法により得られた [Ｈ]
、[Ｓ] 別の割れの限界点は、理論的に求められるもの
とよく合っていた。The hydrogen cracking susceptibility investigation was conducted by the following method. That is, various [H] for each intensity,
The ones with the [S] value are subjected to the same forging → heat treatment to make semi-finished products,
After that, check for cracks by ultrasonic flaw detection (UT),
The limit point of 100% passing was set as the limit point of cracking for each of [H] and [S]. In addition, [H] obtained by such a method
, [S] Another crack limit was in good agreement with what was theoretically required.
【００２５】上記調査の結果を表１に示す。この表１に
おいて、表中の数値が上記でいうところの境界の [Ｈ]
すなわち水素割れ限界 [Ｈ](ppm)である。例えば、
[Ｓ] ＝0.005 質量％、鋼の常温における強度（母材強
度）＝45kgf/cm2 の場合には、水素割れ限界 [Ｈ] ＝1.
7ppmである。なお、この表１は、前述した溶鋼中の水素
量と溶鋼中のＳ量と鋼の耐水素割れ性との関係を示す図
や表等の一例に相当する。The results of the above survey are shown in Table 1. In this Table 1, the numerical values in the table are the boundaries [H]
That is, it is the hydrogen cracking limit [H] (ppm). For example,
Hydrogen cracking limit [H] = 1. When [S] = 0.005 mass% and the strength of steel at room temperature (base metal strength) = 45 kgf / cm 2 .
It is 7 ppm. In addition, Table 1 corresponds to an example of a diagram, a table, or the like showing the relationship between the amount of hydrogen in the molten steel, the amount of S in the molten steel, and the hydrogen crack resistance of the steel described above.
【００２６】上記表１に基づいて図１を得た。即ち、横
軸を [Ｈ](ppm)、縦軸を [Ｓ](質量％）とし、上記表１
の水素割れ限界 [Ｈ] の値を鋼の強度別にプロットし
て、図１を作成した。この図１において、各プロットの
点は上記境界の [Ｈ] すなわち水素割れ限界 [Ｈ](ppm)
に相当する点であり、これらを結んでなる線は水素割れ
感受性を示す場合と示さない場合の境界を示す線であ
る。即ち、各線より下（あるいは右）の領域に入る条件
（ [Ｈ] 、 [Ｓ] ）の場合には水素割れ感受性を示し、
各線より上（あるいは左）の領域に入る条件（ [Ｈ] 、
[Ｓ] ）の場合には水素割れ感受性を示さないことにな
る。なお、この図１は、前述した溶鋼中の水素量と溶鋼
中のＳ量と鋼の耐水素割れ性との関係を示す図や表等の
一例に相当する。FIG. 1 was obtained based on Table 1 above. That is, the horizontal axis is [H] (ppm) and the vertical axis is [S] (mass%),
Fig. 1 was prepared by plotting the values of the hydrogen cracking limit [H] of the steel according to the strength of the steel. In Fig. 1, the points of each plot are [H] at the boundary, that is, hydrogen cracking limit [H] (ppm).
Is a point corresponding to, and the line connecting them is a line showing a boundary between the case where hydrogen cracking susceptibility is exhibited and the case where hydrogen susceptibility is not exhibited. That is, under the conditions ([H], [S]) below (or right) below each line, hydrogen cracking susceptibility is shown,
Condition ([H], which enters the area above (or left) above each line,
In the case of [S], hydrogen susceptibility is not shown. It should be noted that FIG. 1 corresponds to an example of a diagram, table, or the like showing the relationship between the amount of hydrogen in the molten steel, the amount of S in the molten steel, and the hydrogen crack resistance of the steel described above.
【００２７】このようにして表１および図１を求めてお
いてから、溶鋼の精錬を下記のようにして行った。After obtaining Table 1 and FIG. 1 in this way, refining of molten steel was carried out as follows.
【００２８】溶鋼の精錬時に溶鋼中の水素量（ [Ｈ] ）
をオンライン分析にて求めた。この分析方法としては、
図２に示すような水素迅速分析方法を採用した。この分
析の所要時間は約１分であった。同時に、溶鋼中のＳ量
（ [Ｓ] ）をオフライン分析にて求めた。この分析方法
としては、カントバック法（ＱＶ法）（：発光分光分析
法）を採用した。この分析の所要時間は約２分であっ
た。Amount of hydrogen in molten steel ([H]) during refining of molten steel
Was determined by online analysis. For this analysis method,
A hydrogen rapid analysis method as shown in FIG. 2 was adopted. The time required for this analysis was about 1 minute. At the same time, the amount of S in molten steel ([S]) was determined by offline analysis. As this analysis method, the Cantobac method (QV method) (: emission spectroscopic analysis method) was adopted. The time required for this analysis was about 2 minutes.
【００２９】上記 [Ｈ] の分析値を図１に照らし合わ
せ、これにより、水素割れ感受性を示さない領域に移行
させるために最低限必要な [Ｓ] すなわち耐水素割れ性
に優れた鋼を得ることができるときの [Ｓ] の最小値を
求めた。そして、得ようとする鋼の耐水素割れ性だけで
なく、清浄度および機械的性質の点も考慮して、 [Ｓ]
が上記 [Ｓ] の最小値より少し高めの値になるように、
上記 [Ｓ] の最小値および前記 [Ｓ] の分析値に基づい
て溶鋼中へのＳ源（単体硫黄または硫化物）の添加量を
定め、この量のＳ源を溶鋼中へ添加した。The analytical value of the above [H] is checked against FIG. 1 to obtain a steel [S] which is the minimum required for shifting to a region which does not show hydrogen cracking susceptibility, that is, steel excellent in hydrogen cracking resistance. The minimum value of [S] when it was possible was calculated. Then, considering not only the hydrogen cracking resistance of the steel to be obtained but also the cleanliness and mechanical properties, [S]
So that the value becomes a little higher than the minimum value of [S] above,
The amount of the S source (single sulfur or sulfide) added to the molten steel was determined based on the minimum value of the above [S] and the analysis value of the above [S], and this amount of the S source was added into the molten steel.
【００３０】例えば、強度：４５kgf/cm2 級の鋼を製造
する場合において、溶鋼の精錬時にオンライン分析にて
[Ｈ] を求めたところ、 [Ｈ] ＝1.7ppmであった。同時
に、発光分光分析にて [Ｓ] を求めたところ、 [Ｓ] ＝
0.003 質量％であった。この[Ｈ] ＝1.7ppm、 [Ｓ] ＝
0.003 質量％の点は、図１において水素割れ感受性に関
する境界線より下（あるいは右）にあるので、水素割れ
感受性を示す領域にある。このため、この状態のままで
は、水素割れ感受性を示さない（耐水素割れ性に優れ
た）鋼を得ることはできない。For example, in the case of producing a steel having a strength of 45 kgf / cm 2 , an online analysis was performed during refining of molten steel.
When [H] was calculated, [H] was 1.7 ppm. At the same time, when [S] was obtained by optical emission spectroscopy, [S] =
It was 0.003 mass%. This [H] = 1.7 ppm, [S] =
Since the point of 0.003 mass% is below (or on the right of) the boundary line regarding hydrogen cracking susceptibility in Fig. 1, it is in the region showing hydrogen cracking sensitivity. Therefore, in this state as it is, it is not possible to obtain a steel which does not exhibit hydrogen cracking susceptibility (excellent in hydrogen cracking resistance).
【００３１】そこで、 [Ｈ] ＝1.7ppmのときにおいて、
水素割れ感受性を示さない領域に移行させるために最低
限必要な [Ｓ] を図１より求めると、それは0.005 質量
％である。従って、得ようとする鋼の耐水素割れ性の点
からは、 [Ｓ] を0.005 質量％超で出来るだけ多くなる
ようにするとよい。しかし、 [Ｓ] を多くし過ぎると清
浄度や機械的性質が悪くなり過ぎる。そこで、鋼の耐水
素割れ性の点だけではなく、清浄度および機械的性質の
点も考慮して、 [Ｓ] が前記分析の時点における0.003
質量％から0.005 質量％より少し高めの値に移行して0.
007 質量％になるように、溶鋼中へのＳ源の添加量を定
め、この量のＳ源を溶鋼中へ添加した。Therefore, when [H] = 1.7 ppm,
The minimum [S] required to transfer to a region that does not show hydrogen cracking susceptibility is 0.005 mass% when calculated from Fig. 1. Therefore, from the viewpoint of hydrogen cracking resistance of the steel to be obtained, it is advisable to increase [S] as much as possible in excess of 0.005 mass%. However, if the amount of [S] is too large, the cleanliness and mechanical properties become too poor. Therefore, considering not only the hydrogen cracking resistance of steel but also the cleanliness and mechanical properties, [S] is 0.003 at the time of the above analysis.
Change from a mass% to a value slightly higher than 0.005 mass% to 0.
The amount of the S source added to the molten steel was determined so that it would be 007% by mass, and this amount of the S source was added to the molten steel.
【００３２】このようにして溶鋼の精錬時にＳ源の添加
量を定め、この量のＳ源を溶鋼中へ添加して [Ｓ] を調
整した。このような調整がされた溶鋼の [Ｓ] 、 [Ｈ]
は、いずれの場合も、図１において水素割れ感受性を示
さない領域にあり、且つ、水素割れ感受性に関する境界
線より少し上（あるいは左）に位置する。例えば、強
度：45kgf/cm2 級の鋼を製造する場合、このような調整
がされた溶鋼の [Ｓ] 、[Ｈ] は、いずれの場合も、図
１中に図示した楕円で囲まれた領域（その中に本発明法
と記した個所）内にある。この領域内での [Ｓ] は
[Ｓ] ＝0.003 〜0.012 質量％であり、後述の従来技術
の場合に比べて低い。In this way, the amount of S source added was determined during the refining of molten steel, and this amount of S source was added into the molten steel to adjust [S]. [S], [H] of molten steel adjusted in this way
In any case, is in a region that does not show hydrogen cracking susceptibility and is located slightly above (or left) the boundary line regarding hydrogen cracking susceptibility. For example, when producing steel of strength: 45 kgf / cm 2, the molten steels [S] and [H] thus adjusted are surrounded by the ellipse shown in FIG. Within the area (where the method of the invention is noted therein). [S] in this area is
[S] = 0.003 to 0.012% by mass, which is lower than that of the prior art described later.
【００３３】これに対して、従来技術のように [Ｈ] お
よび [Ｓ] の範囲を安全側に定めて管理する場合は、溶
鋼の精錬時にＳ源を添加した後の溶鋼の [Ｓ] 、 [Ｈ]
は、図１において水素割れ感受性を示さない領域にある
が、水素割れ感受性に関する境界線より大分上（あるい
は左）に位置する。例えば、強度：45kgf/cm2 級の鋼を
製造する場合、Ｓ源の添加後の溶鋼の [Ｓ] 、 [Ｈ]
は、いずれの場合も、図１中に図示した四角で囲まれた
領域（その中に45kgf での従来の管理範囲と記した個
所）内にある。この領域内での [Ｓ] は [Ｓ] ＝0.008
〜0.015 質量％である。On the other hand, when the ranges of [H] and [S] are controlled on the safe side as in the prior art, [S] of molten steel after addition of S source during refining of molten steel, [H]
1 is located in a region where hydrogen cracking susceptibility is not shown in FIG. 1, but is much higher (or left) than the boundary line regarding hydrogen cracking susceptibility. For example, when producing steel of strength: 45 kgf / cm 2 , [S], [H] of molten steel after addition of S source
In each case, the area is within the boxed area shown in FIG. 1 (where the conventional management range at 45 kgf is marked). [S] in this region is [S] = 0.008
~ 0.015% by mass.
【００３４】前記溶鋼の精錬の後、得られた鋼塊を用い
て前記所定の工程と同様の工程を経て丸棒（例えばφ60
0mm の丸棒）を製造した。そして、この丸棒から試験材
を採取し、清浄度の測定、引っ張り試験や曲げ試験等に
よる機械的性質の測定、および、水素割れ感受性調査を
行った。このとき、清浄度の測定および機械的性質の測
定は通常の方法（JIS に規定する方法）により行った。
水素割れ感受性調査は前記水素割れ感受性調査の場合と
同様の方法により行った。After the refining of the molten steel, the obtained steel ingot is used to go through the same steps as the above-mentioned predetermined steps, and a round bar (for example, φ60).
0 mm round bar) was manufactured. Then, a test material was sampled from this round bar, and the cleanliness was measured, mechanical properties were measured by a tensile test, a bending test, and the like, and hydrogen cracking susceptibility was investigated. At this time, the measurement of cleanliness and the measurement of mechanical properties were carried out by a usual method (method specified in JIS).
The hydrogen cracking susceptibility investigation was performed by the same method as in the case of the hydrogen cracking susceptibility investigation.
【００３５】この結果、強度：45kgf/cm2 級の鋼の製造
に際し、従来技術のように [Ｈ] および [Ｓ] の範囲を
安全側に定めて管理する場合（比較例の場合）は、得ら
れた鋼は耐水素割れ性に優れていたが、介在物であるＭ
ｎＳの量が多くて清浄度が悪く、また、強度および伸び
が低く、靱性も低くて機械的性質が悪かった。As a result, when manufacturing steel with a strength of 45 kgf / cm 2 class, when the ranges of [H] and [S] are controlled to be safe as in the prior art (in the case of the comparative example), Although the obtained steel was excellent in hydrogen cracking resistance, it was an inclusion M
The amount of nS was large, the cleanliness was poor, the strength and elongation were low, and the toughness was low, resulting in poor mechanical properties.
【００３６】これに対し、前記のように溶鋼の精錬時に
[Ｈ] を分析して求め、これに基づいてＳ源の添加量を
定め、この量のＳ源を溶鋼中へ添加して [Ｓ] を調整し
た場合（本発明の実施例の場合）は、得られた鋼は比較
例の場合と同様に耐水素割れ性に優れているだけでな
く、比較例の場合に比較してＭｎＳの量が著しく少なく
て極めて清浄度に優れ、また、強度および伸びが著しく
高く、靱性も高くて機械的性質に極めて優れていた。On the other hand, as described above, when refining molten steel,
When [H] is determined by analysis, the amount of S source added is determined based on this, and [S] is adjusted by adding this amount of S source into the molten steel (in the case of the embodiment of the present invention), The obtained steel is not only excellent in hydrogen cracking resistance as in the case of the comparative example, but also has an extremely small amount of MnS as compared with the case of the comparative example and is extremely excellent in cleanliness. The elongation was extremely high, the toughness was high, and the mechanical properties were extremely excellent.
【００３７】強度：60kgf/cm2 級の鋼の製造の場合も、
本発明の実施例の場合は、得られた鋼は比較例の場合と
同様に耐水素割れ性に優れているだけでなく、比較例の
場合よりもＭｎＳの量が著しく少なくて極めて清浄度に
優れ、また、強度および伸びが著しく高く、靱性も高く
て機械的性質に極めて優れていた。強度：75kgf/cm
2級、80kgf/cm2 級、85kgf/cm2 級、90kgf/cm2 級の鋼
の製造の場合も、本発明の実施例の場合は、得られた鋼
は比較例の場合と同様に耐水素割れ性に優れているだけ
でなく、比較例の場合よりもＭｎＳの量が著しく少なく
て極めて清浄度に優れ、また、強度および伸びが著しく
高く、靱性も高くて機械的性質に極めて優れていた。Strength: In the case of manufacturing steel of 60 kgf / cm 2 grade,
In the case of the example of the present invention, not only the obtained steel is excellent in hydrogen cracking resistance as in the case of the comparative example, but also the amount of MnS is remarkably smaller than that of the comparative example and the cleanliness is extremely high. It was also excellent in strength and elongation, toughness, and mechanical properties. Strength: 75kgf / cm
Secondary, 80 kgf / cm 2 grade, 85 kgf / cm 2 grade, even if the production of 90 kgf / cm 2 grade of steel, the embodiment of the present invention, the resulting steel resistant as in the Comparative Example Not only is it excellent in hydrogen cracking, but it also has an extremely small amount of MnS and is extremely excellent in cleanliness compared with the case of the comparative example, and also has extremely high strength and elongation, high toughness, and extremely excellent mechanical properties. It was
【００３８】このように本発明の実施例の場合、溶鋼の
精錬時に [Ｈ] に応じて [Ｓ] を調整するので、 [Ｓ]
を過不足のない量にすることができ、このため、耐水素
割れ性を確保した上で、 [Ｓ] を不必要に高くし過ぎる
ことがないようにすることができる。従って、本発明の
実施例の場合は、耐水素割れ性を確保した上で、比較例
の場合に比べて、 [Ｓ] を的確に低くすることができ、
このため、ＭｎＳの量が著しく少なくて極めて清浄度に
優れると共に機械的性質に極めて優れた鋼を得ることが
できるようになる。As described above, in the case of the embodiment of the present invention, since [S] is adjusted in accordance with [H] during refining of molten steel, [S]
Can be set to a sufficient amount, and therefore, [S] can be prevented from becoming unnecessarily high while ensuring hydrogen cracking resistance. Therefore, in the case of the example of the present invention, [S] can be appropriately lowered as compared with the case of the comparative example while ensuring hydrogen cracking resistance,
Therefore, it becomes possible to obtain a steel having a remarkably small amount of MnS, which is extremely excellent in cleanliness and mechanical properties.
【００３９】前述の図１における水素割れ感受性に関す
る境界線は、下記式（近似式）(2)で表現することがで
きる。
[Ｓ] ＝（α [Ｈ] ／Ａ）＋β -------- 式(2)
但し、上記式(2) において、 [Ｈ] は溶鋼中の水素量の
測定値（ppm)、 [Ｓ]は溶鋼中のＳ量（質量％）、Ａは
鋼の常温における強度（kgf/cm2)である。α、βは定数
であって、 [Ｈ] ／Ａ≦0.073 のときは、α＝0.136 、
β＝０であり、[Ｈ] ／Ａ＞0.073 のときは、α＝0.571
、β＝−0.032 である。The boundary line relating to hydrogen cracking susceptibility in FIG. 1 can be expressed by the following equation (approximate equation) (2). [S] = (α [H] / A) + β -------- Equation (2) However, in the above equation (2), [H] is the measured value (ppm) of the amount of hydrogen in the molten steel, [S] is the amount of S (% by mass) in the molten steel, and A is the strength of the steel at room temperature (kgf / cm 2 ). α and β are constants, and when [H] /A≦0.073, α = 0.136,
When β = 0 and [H] / A> 0.073, α = 0.571
, Β = −0.032.
【００４０】従って、図１において水素割れ感受性を示
さない領域は、下記式(3) で表現することができる。
[Ｓ] ≧（α [Ｈ] ／Ａ）＋β -------- 式(3)Therefore, the region which does not show hydrogen cracking susceptibility in FIG. 1 can be expressed by the following equation (3). [S] ≧ (α [H] / A) + β -------- Equation (3)
【００４１】故に、溶鋼の精錬時に溶鋼中へＳ源を添加
して [Ｓ] を調整する際、耐水素割れ性に優れた鋼を得
るためには、 [Ｈ] の値に応じて [Ｓ] を上記の式(3)
を満たす値に調整するとよいことになる。Therefore, when the S source is added to the molten steel during the refining of the molten steel to adjust the [S], in order to obtain a steel excellent in hydrogen cracking resistance, the [S] should be adjusted according to the value of the [H]. ] To the above formula (3)
It is good to adjust to a value that satisfies.
【００４２】[0042]
【表１】 [Table 1]
【００４３】[0043]
【発明の効果】本発明に係る溶鋼の精錬方法によれば、
耐水素割れ性に優れた鋼を得るために溶鋼の精錬時にＳ
源を添加して溶鋼中のＳ量を調整するに際し、溶鋼中の
Ｓ量を過不足なく調整することができるようになる。According to the method for refining molten steel according to the present invention,
In order to obtain steel with excellent hydrogen cracking resistance, S is used during the refining of molten steel.
When the amount of S in molten steel is adjusted by adding a source, the amount of S in molten steel can be adjusted without excess or deficiency.
【図面の簡単な説明】[Brief description of drawings]
【図１】 溶鋼中の [Ｈ] と [Ｓ] との関係を示す図で
ある。FIG. 1 is a diagram showing a relationship between [H] and [S] in molten steel.
【図２】 溶鋼中の水素量を迅速に測定することができ
る水素迅速分析方法の概要を示す図である。FIG. 2 is a diagram showing an outline of a rapid hydrogen analysis method capable of rapidly measuring the amount of hydrogen in molten steel.
【図３】 溶鋼試料採取法による水素の分析方法の概要
を示す図である。FIG. 3 is a diagram showing an outline of a hydrogen analysis method by a molten steel sampling method.
Claims (2)
鋼の精錬時にＳ源を添加して溶鋼中のＳ量を調整する溶
鋼の精錬方法であって、溶鋼の精錬時に溶鋼中の水素量
を測定し、この水素量の測定値に基づいて溶鋼中へのＳ
源の添加量を定め、このＳ源を添加して溶鋼中のＳ量を
調整することを特徴とする溶鋼の精錬方法。1. A method for refining molten steel in which a source of S is added during refining of molten steel to adjust the amount of S in the molten steel in order to obtain steel having excellent hydrogen cracking resistance. The amount of hydrogen is measured, and S in molten steel is measured based on the measured amount of hydrogen.
A method for refining molten steel, characterized in that an addition amount of a source is determined and the S source is added to adjust the amount of S in the molten steel.
値に調整する請求項１記載の溶鋼の精錬方法。 [Ｓ] ≧（α [Ｈ] ／Ａ）＋β -------- 式(1) 但し、上記式(1) において、 [Ｈ] は溶鋼中の水素量の
測定値（ppm)、 [Ｓ]は溶鋼中のＳ量（質量％）、Ａは
鋼の常温における強度（kgf/cm2)である。α、βは定数
であって、 [Ｈ] ／Ａ≦0.073 のときは、α＝0.136 、
β＝０であり、[Ｈ] ／Ａ＞0.073 のときは、α＝0.571
、β＝−0.032 である。2. The method for refining molten steel according to claim 1, wherein the amount of S in the molten steel is adjusted to a value satisfying the following formula (1). [S] ≧ (α [H] / A) + β -------- Formula (1) However, in the above formula (1), [H] is the measured value (ppm) of the amount of hydrogen in the molten steel, [S] is the amount of S (% by mass) in the molten steel, and A is the strength of the steel at room temperature (kgf / cm 2 ). α and β are constants, and when [H] /A≦0.073, α = 0.136,
When β = 0 and [H] / A> 0.073, α = 0.571
, Β = −0.032.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1978124A1 (en) | 2007-04-05 | 2008-10-08 | Kabushiki Kaisha Kobe Seiko Sho | Forging steel, forging and crankshaft |
| KR101400047B1 (en) | 2012-04-26 | 2014-05-27 | 현대제철 주식회사 | Control method for casting of ultra low carbon steel |
| US9297056B2 (en) | 2011-02-24 | 2016-03-29 | Kobe Steel, Ltd. | Forged steel and welded structure for components for nuclear power plants |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6362815A (en) * | 1986-09-03 | 1988-03-19 | Daido Steel Co Ltd | Method for refining molten steel |
| JPS6362814A (en) * | 1986-09-03 | 1988-03-19 | Daido Steel Co Ltd | Manufacture of low hydrogen steel |
| JPS63161113A (en) * | 1986-12-24 | 1988-07-04 | Daido Steel Co Ltd | Method for refining steel |
| JPH0570821A (en) * | 1991-09-17 | 1993-03-23 | Nippon Steel Corp | Dehydrogenation refining method |
| JPH09227989A (en) * | 1996-02-22 | 1997-09-02 | Sumitomo Metal Ind Ltd | Calcium-treated steel and treatment of molten steel with calcium |
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2002
- 2002-03-08 JP JP2002063355A patent/JP3838496B2/en not_active Expired - Fee Related
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6362815A (en) * | 1986-09-03 | 1988-03-19 | Daido Steel Co Ltd | Method for refining molten steel |
| JPS6362814A (en) * | 1986-09-03 | 1988-03-19 | Daido Steel Co Ltd | Manufacture of low hydrogen steel |
| JPS63161113A (en) * | 1986-12-24 | 1988-07-04 | Daido Steel Co Ltd | Method for refining steel |
| JPH0570821A (en) * | 1991-09-17 | 1993-03-23 | Nippon Steel Corp | Dehydrogenation refining method |
| JPH09227989A (en) * | 1996-02-22 | 1997-09-02 | Sumitomo Metal Ind Ltd | Calcium-treated steel and treatment of molten steel with calcium |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1978124A1 (en) | 2007-04-05 | 2008-10-08 | Kabushiki Kaisha Kobe Seiko Sho | Forging steel, forging and crankshaft |
| US9297056B2 (en) | 2011-02-24 | 2016-03-29 | Kobe Steel, Ltd. | Forged steel and welded structure for components for nuclear power plants |
| KR101400047B1 (en) | 2012-04-26 | 2014-05-27 | 현대제철 주식회사 | Control method for casting of ultra low carbon steel |
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