JPH0645818B2 - Bearing steel manufacturing method - Google Patents
Bearing steel manufacturing methodInfo
- Publication number
- JPH0645818B2 JPH0645818B2 JP63044952A JP4495288A JPH0645818B2 JP H0645818 B2 JPH0645818 B2 JP H0645818B2 JP 63044952 A JP63044952 A JP 63044952A JP 4495288 A JP4495288 A JP 4495288A JP H0645818 B2 JPH0645818 B2 JP H0645818B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- molten steel
- converter
- vacuum degassing
- inclusions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Description
本発明は清浄鋼、特に高級軸受鋼の製造方法に係り、軸
受鋼の転動疲労寿命を決定する鋼中介在物を効率よく低
減し得る方法に関する。The present invention relates to a method for producing clean steel, particularly high-grade bearing steel, and more particularly to a method capable of efficiently reducing inclusions in steel that determine the rolling contact fatigue life of bearing steel.
高級軸受鋼は強度、耐食性を考慮してCr添加鋼が用いら
れるが、このような鋼の寿命は転動疲労寿命により決定
される。この転動疲労寿命は鋼中の介在物により決定さ
れるため、この転動疲労寿命を延ばすためには鋼中の
Ｓ，Ｏ（以下[S],[O]と記す）を可及的に低減すること
が必要である。このことは、第６図に示す転動疲労寿命
におよぼす[S],[O]の影響より明らかである。 この[S],[O]の低減化にいては、快削性の問題があり、
[S]は一概に低下させることができないという理由によ
り、低[O]化が注目されている。この場合の[O]は鋼中の
全酸素量（以下T[O]と記す）と称され、未反応状態で含
有されている活量酸素（以下Free[O]と記す）と、介在
物例えばAl2O3の形で含有している酸素との和で表現さ
れる。この介在物の影響は第７図に示す通りである。 T[O]の低減化においては、１％Ｃ鋼中のFree[O]は約３p
pm程度であることから、現在ではAl2O3等の介在物とし
て鋼中に含有されている[O]が問題になっている。 このように鋼中に含有される酸素のうち、介在物として
の生成を、低減する方法としては、下記、のパター
ンがある。 2Al＋3/2O2＝Al2O3 2Al＋3/y(MxOy)＝Al2O3＋(3x/y)M ただし、Ｍ：Fe,Si,Mn,Cr等の金属 すなわち、は真空脱ガス処理における昇熱、連続鋳造
での空気酸化によるパターンであり、はスラグあるい
は鍋耐火物との酸化還元反応によるパターンである。 このうち、のパターンの対策としては、例えば、真空
脱ガス処理時間を長くする方法（特開昭57-73118号公
報）、真空脱ガス処理を強力に行なう方法（特開昭61-2
95314号公報）が知られている。前者は真空脱ガス処理
を５分程度行なうことによって溶鋼中に存在するAl2O3
をスラグ中に浮上させ鋼の清浄度を高める方法であり、
後者は脱ガス処理前に脱ガス処理で容易に抜くことがで
きる気体を溶鋼中に添加し、真空脱ガス装置により強脱
ガス処理することにより添加ガスとともに酸素ガスも抜
く方法である。As high-grade bearing steel, Cr-added steel is used in consideration of strength and corrosion resistance, and the life of such steel is determined by rolling fatigue life. Since this rolling fatigue life is determined by the inclusions in the steel, S and O in the steel (hereinafter referred to as [S], [O]) are as much as possible in order to extend this rolling fatigue life. It is necessary to reduce. This is clear from the effect of [S] and [O] on the rolling fatigue life shown in FIG. In reducing [S] and [O], there is a problem of free-cutting,
Low [O] is attracting attention because [S] cannot be lowered unconditionally. In this case, [O] is called the total oxygen amount in the steel (hereinafter referred to as T [O]), and the active oxygen contained in the unreacted state (hereinafter referred to as Free [O]) and inclusions. For example, it is expressed as the sum of oxygen contained in the form of Al 2 O 3 . The influence of this inclusion is as shown in FIG. In reducing T [O], Free [O] in 1% C steel is about 3p
Since it is about pm, [O] contained in steel as inclusions such as Al 2 O 3 is now a problem. As a method of reducing the formation of inclusions as oxygen among the oxygen contained in the steel, there are the following patterns. 2Al + 3 / 2O 2 ＝ Al 2 O 3 2Al ＋ 3 / y (M x O y ) ＝ Al 2 O 3 ＋ (3x / y) M However, M: Fe, Si, Mn, Cr and other metals, that is, vacuum degassing It is a pattern due to heating in treatment, air oxidation in continuous casting, and a pattern due to redox reaction with slag or pot refractory. Among these, as measures against the pattern, for example, a method of lengthening the vacuum degassing treatment time (Japanese Patent Laid-Open No. 57-73118) and a method of strongly performing the vacuum degassing treatment (Japanese Patent Laid-Open No. 61-2)
No. 95314) is known. In the former case, Al 2 O 3 present in the molten steel can be obtained by performing vacuum degassing for about 5 minutes.
Is a method of raising the cleanliness of steel by levitating in the slag,
The latter is a method in which a gas that can be easily degassed by degassing is added to molten steel before degassing, and strong degassing is performed by a vacuum degassing device to remove oxygen gas together with the added gas.
しかし、真空脱ガス槽内で処理時間を長くしたり、ある
いは強脱ガス処理を行なって鋼の清浄度を高める方法
は、溶鋼中のT[O]低減に有効ではあるが、溶鋼の温度低
下を余儀なくされるという問題があり、この好ましくな
かった。 本発明は従来の技術のこのような問題点に鑑みなされた
ものであり、その目的とするところは真空処理時間を30
分以上と長くしても溶鋼温度を低下させることなく低T
[O]化できる軸受鋼の製造方法を提案しようとするもの
である。However, the method of increasing the cleanliness of the steel by increasing the treatment time in the vacuum degassing tank or performing strong degassing treatment is effective in reducing T [O] in the molten steel, but lowers the temperature of the molten steel. This was not desirable because there was a problem of being forced to. The present invention has been made in view of such problems of the conventional technique, and the object thereof is to reduce the vacuum processing time to 30
Low T without lowering the molten steel temperature even if it is longer than a minute
The purpose is to propose a method for producing bearing steel that can be converted to [O].
本発明は真空脱ガス処理時間を長くすることによる溶鋼
温度の低下を避けるため、真空脱ガス処理前に溶鋼の温
度を高めて真空処理槽の処理に移行するようにしたもの
で、その要旨は真空脱ガス処理前の転炉内溶鋼にコーク
ス等の炭材およびCr合金鉄を投入し、さらに転炉出鋼中
にCaO-CaF2系合成スラグを添加し、真空処理槽にて少な
くとも30分以上継続して真空脱ガス処理を行なうことに
よって、Al2O3等の介在物の低減をはかることを特徴と
するものである。The present invention, in order to avoid lowering the molten steel temperature by increasing the vacuum degassing time, the temperature of the molten steel is raised before the vacuum degassing process and the process is transferred to the vacuum treatment tank. Carbon materials such as coke and Cr alloy iron are added to the molten steel in the converter before vacuum degassing, and CaO-CaF 2 system synthetic slag is added to the steel output from the converter for at least 30 minutes in the vacuum treatment tank. It is characterized in that inclusions such as Al 2 O 3 are reduced by continuously performing the vacuum degassing process.
転炉内溶鋼の温度を高めて真空脱ガス処理槽の処理に移
行すると、真空処理中に溶鋼温度低下が生じても、真空
脱ガス処理槽からの出鋼時の溶鋼温度を確保することが
できる。すなわち、真空脱ガス処理槽での溶鋼温度が高
ければ昇熱用に添加されるAl量を少なくでき、ひいて
は、Al2O3の生成が少なくなり、鋼中T[O]の低減化がは
かられることが明白である。 このため、本発明では溶鋼の真空脱ガス処理の開始温度
を高めるために出鋼温度を高める手段として、転炉内溶
鋼にコークス等の炭材と、Cr合金鉄を添加する方法をこ
うじたのである。 ここで、転炉内溶鋼にコークス等の炭材を添加すると溶
鋼温度は上昇するが、炭材は[S]を含むため溶鋼中[S]量
が増加する。そこで、この炭材添加による[S]の増加に
対しては、転炉からの出鋼中にCaO-CaF2系合成スラグを
添加することによって対処している。つまり、CaO-CaF2
系合成スラグは溶鋼中の[S]の吸収能が高いため溶鋼中
の介在物を少なくできる。したがって、出鋼中にCaO-Ca
F2係合成スラグを添加することによって溶鋼中[S]量の
増加抑制ならびに鋼中介在物の低減が可能となる。 また、軸受鋼の転動疲労寿命の延長には、低Ti化も効果
があると云われている。一方、Cr合金鉄には一般にTiが
含有され、酸化精錬工程がなければTiの除去が困難であ
ったが、今回転炉にてCr合金鉄を添加することによっ
て、低いTi化が図られると共に、転炉出鋼中にCr合金鉄
を添加することによる温度降下にも対処できる。 このように、溶鋼の真空脱ガス処理の開始温度を高くで
きることにより、真空脱ガス処理槽では30分以上の脱ガ
ス処理時間を確保することが可能となり、溶鋼中の介在
物の浮上促進がはかられる。これにより、鋼中T[O]を低
位に安定させることができるのである。 第１図は本発明方法の説明図であり、(1)は転炉、(2)は
ＲＨ脱ガス装置、(3)は連続鋳造設備である。 すなわち、本発明では、ＲＨ脱ガス処理前の転炉(1)内
溶鋼に熱源を確保するための炭材として、例えばコーク
ス(4)とCr合金鉄(5)を添加する。この時のコークスの添
加量としては、例えば１％Ｃ、1.4％Cr鋼の高級軸受鋼
の場合は19kg／Ｔ程度でよい。 さらに、従来の出鋼中に添加するがCr合金鉄による温度
降下の抑制と、Cr合金鉄中のTiの酸化を防止すうため
に、転炉内溶鋼中にCr合金鉄を添加するが、このCr合金
鉄の添加量は20〜30kg／Ｔの範囲が好ましい。 次に、この昇温せしめた転炉内溶鋼を真空脱ガス装置
(2)に出鋼するが、炭材の添加による[S]の増加に対処す
るため、出鋼中に[S]吸収能の高いCaO-CaF2系合成スラ
グ(6)を添加する。このCaO-CaF2系合成スラグ(6)の添加
により出鋼中に脱[S]がはかられる。また、このCaO-CaF
2系合成スラグ(6)は、Al2O3介在物の吸収能も高く、鋼
中介在物の低減も図ることができる。なお、このCaO-Ca
F2系合成スラグ(6)の添加量としては、６〜８kg／Ｔで
組成比率は、CaO：CaF2＝７：３程度でよい。 真空脱ガス装置(2)では、溶鋼の還流を少なくとも30分
以上継続して行なう。この30分以上の脱ガス処理によ
り、Al2O3介在物の浮上促進がより一層はかられ、溶鋼
中のＴ[O]を安定して低減できる。If the temperature of the molten steel in the converter is increased and the process is transferred to the vacuum degassing tank, even if the molten steel temperature drops during vacuum processing, it is possible to secure the molten steel temperature during tapping from the vacuum degassing tank. it can. That is, if the temperature of the molten steel in the vacuum degassing tank is high, the amount of Al added for heating can be reduced, and as a result, the amount of Al 2 O 3 produced is reduced, and the T [O] in the steel cannot be reduced. It's clear that it gets tangled. Therefore, in the present invention, as a means for increasing the tapping temperature in order to increase the starting temperature of the vacuum degassing treatment of molten steel, a carbon material such as coke, etc. in the molten steel in the converter, and a method of adding Cr alloy iron is there. When a carbon material such as coke is added to the molten steel in the converter, the molten steel temperature rises, but the carbon material contains [S], so the [S] content in the molten steel increases. Therefore, the increase in [S] due to the addition of carbonaceous material is addressed by adding CaO-CaF 2 -based synthetic slag during tapping from the converter. That is, CaO-CaF 2
Since synthetic slag has a high [S] absorption capacity in molten steel, it can reduce the inclusions in the molten steel. Therefore, during tapping, CaO-Ca
By adding the F 2 -based synthetic slag, it is possible to suppress the increase of the [S] amount in the molten steel and reduce the inclusions in the steel. It is also said that lowering Ti is effective in extending the rolling fatigue life of bearing steel. On the other hand, Cr alloyed iron generally contains Ti, and it was difficult to remove Ti without an oxidizing and refining process, but by adding Cr alloyed iron in a rotary furnace, it is possible to achieve low Ti and Also, it is possible to deal with the temperature drop due to the addition of Cr alloy iron in the steel output from the converter. In this way, since the starting temperature of the vacuum degassing treatment of molten steel can be increased, it is possible to secure a degassing treatment time of 30 minutes or more in the vacuum degassing treatment tank, and to promote the floating of inclusions in the molten steel. Get rid of. This makes it possible to stabilize T [O] in steel at a low level. FIG. 1 is an explanatory view of the method of the present invention. (1) is a converter, (2) is an RH degassing device, and (3) is a continuous casting facility. That is, in the present invention, for example, coke (4) and Cr alloy iron (5) are added as carbon materials for securing a heat source in the molten steel in the converter (1) before the RH degassing process. The amount of coke added at this time may be about 19 kg / T in the case of high-grade bearing steel such as 1% C and 1.4% Cr steel. Furthermore, in order to suppress the temperature drop due to Cr alloy iron and to prevent the oxidation of Ti in Cr alloy iron, which is added to the conventional tapping steel, Cr alloy iron is added to the molten steel in the converter. The amount of Cr alloy iron added is preferably in the range of 20 to 30 kg / T. Next, the molten steel in the converter, which has been heated, is vacuum degassed.
Steel is tapped in (2), but in order to cope with the increase in [S] due to the addition of carbonaceous material, CaO-CaF 2 -based synthetic slag (6) having a high [S] absorption capacity is added during tapping. The addition of this CaO-CaF 2 based synthetic slag (6) removes [S] during tapping. Also, this CaO-CaF
The 2 type synthetic slag (6) has a high absorption capacity for Al 2 O 3 inclusions, and can also reduce inclusions in steel. In addition, this CaO-Ca
The amount of the F 2 -based synthetic slag (6) added is 6 to 8 kg / T, and the composition ratio may be about CaO: CaF 2 = 7: 3. In the vacuum degassing device (2), the molten steel is continuously refluxed for at least 30 minutes. By this degassing treatment for 30 minutes or longer, the floating of Al 2 O 3 inclusions is further promoted, and T [O] in the molten steel can be stably reduced.
Ｃ：１％，Mn：0.30％，Ｐ：0.008％，Ｓ：0.002％を含
有する溶鋼を転炉にて160トン精錬し、その際炭材とし
てコークスを12.5kg／Ｔ、Cr合金鉄を25kg／Ｔ添加し
た。その時の溶鋼温度は1670〜1700℃であった。 この溶鋼を転炉から取鍋に出鋼する際、組成比率がCa
O：CaF2＝７：３であるCaO−CaF2系合成スラグを７kg／
Ｔ添加し、このCaO−CaF2系合成スラグが添加された状
態で取鍋を真空脱ガス処理場に移し、ここで30分以上の
脱ガス処理を行なった。 本発明の有効性を説明するための真空脱ガス処理槽での
Al使用量とブルーム中Ｔ[O]の関係を第２図に、転炉か
ら取鍋への出鋼中脱[S]効果をCaO−CaF2系合成スラグの
添加なしの場合と比較して第３図に、ＲＨ脱ガス処理時
間とブルーム中T[O]の関係を第４図に、ビレット中T[O]
量とAl2O3介在物[O]の比率の関係を第５図にそれぞれ示
す。 第２図より、真空脱ガス処理槽での溶鋼温度が高ければ
昇熱に用いるAl量を少なくできる結果、低T[O]化がはか
られることが明白である。 第３図より、転炉からの出鋼中にCaO−CaF2系合成スラ
グを添加することによって溶鋼中[S]量を低減できるこ
とがわかる。 また、第４図より明らかなごとく、ＲＨ脱ガス処理時間
を30分以上確保することによって鋼中のT[O]量を低位に
安定させることができる。 さらに、第５図により明らかなように、ビレットの中T
[O]の低下とともにAl2O3介在物を低位に抑えることが可
能となった。Molten steel containing C: 1%, Mn: 0.30%, P: 0.008%, S: 0.002% was smelted in a converter with 160 tons of coke, 12.5 kg / T of coke and 25 kg of Cr alloy iron. / T was added. The molten steel temperature at that time was 1670 to 1700 ° C. When tapping this molten steel from the converter to the ladle, the composition ratio is Ca
O: CaF 2 = 7: 3 CaO-CaF 2 based synthetic slag 7 kg /
After adding T and adding the CaO—CaF 2 -based synthetic slag, the ladle was moved to a vacuum degassing plant, where degassing was carried out for 30 minutes or longer. In a vacuum degassing tank to illustrate the effectiveness of the present invention
The relationship between the amount of Al used and T [O] in the bloom is shown in Fig. 2, and the effect of removing [S] from the converter to the ladle during tapping is compared with that without addition of CaO-CaF 2 synthetic slag. Fig. 3 shows the relationship between RH degassing treatment time and T [O] in bloom. Fig. 4 shows T [O] in billet.
The relationship between the amount and the ratio of Al 2 O 3 inclusions [O] is shown in FIG. 5, respectively. From FIG. 2, it is clear that if the temperature of molten steel in the vacuum degassing tank is high, the amount of Al used for heating can be reduced, and as a result, lower T [O] can be achieved. From FIG. 3, it can be seen that the amount of [S] in the molten steel can be reduced by adding the CaO-CaF 2 -based synthetic slag during tapping from the converter. Further, as is clear from FIG. 4, by securing the RH degassing treatment time of 30 minutes or more, the T [O] content in the steel can be stabilized at a low level. Furthermore, as is clear from FIG. 5, the T inside the billet
It became possible to suppress Al 2 O 3 inclusions to a low level with the decrease in [O].
以上説明したごとく、本発明によれば、溶鋼温度を維持
して真空脱ガス処理を30以上と長く行なうことができる
ので、Al2O3等介在物の浮上促進効果が大きく鋼中酸素
量を大幅に低減でき、清浄度の高い高級軸受鋼の製造が
可能となり、そのもたらす効果は甚大である。As described above, according to the present invention, the vacuum degassing treatment can be performed for as long as 30 or more while maintaining the molten steel temperature, so that the floating promotion effect of inclusions such as Al 2 O 3 is large and the oxygen content in the steel is increased. It is possible to reduce significantly, and it becomes possible to manufacture high-grade bearing steel with high cleanliness, and the resulting effect is enormous.
第１図は本発明方法の説明図、第２図は本発明の有効性
を説明するためのAl使用量とブルーム中Ｔ[O]の関係を
示す図、第３図は同じく転炉からの出鋼時の脱[S]効果
を示す図、第４図は同じくＲＨ脱ガス処理時間とブルー
ム中Ｔ[O]の関係を示す図、第５図は同じくビレット中
Ｔ[O]とFree[O]の比率の関係を示す図、第６図は軸受鋼
の転動疲労寿命におよぼす鋼中[S]、[O]の影響を示すも
ので、図(A)は鋼中[S]の影響を、図(B)は鋼中[O]の影響
をそれぞれ示す図、第７図は同じくAl2O3介在物の影響
を示す図である。 １……転炉、２……ＲＨ脱ガス装置 ３……連続鋳造設備FIG. 1 is an explanatory diagram of the method of the present invention, FIG. 2 is a diagram showing the relationship between the amount of Al used and T [O] in bloom for explaining the effectiveness of the present invention, and FIG. Fig. 4 shows the de [S] effect during tapping, Fig. 4 shows the relationship between RH degassing time and T [O] in bloom, and Fig. 5 also shows T [O] and Free [in billet. Fig. 6 shows the relationship of the ratio of [O], Fig. 6 shows the influence of [S] and [O] in the steel on the rolling contact fatigue life of bearing steel. FIG. 7B is a diagram showing the influence of [O] in steel, and FIG. 7 is a diagram showing the influence of Al 2 O 3 inclusions. 1 ... Converter, 2 ... RH degasser 3 ... Continuous casting equipment
───────────────────────────────────────────────────── フロントページの続き (72)発明者 友野 宏 和歌山県和歌山市湊1850番地 住友金属工 業株式会社和歌山製鉄所内 (72)発明者 市原 清 和歌山県和歌山市湊1850番地 住友金属工 業株式会社和歌山製鉄所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Tomo, 1850 Minato, Wakayama, Wakayama Sumitomo Metal Industries, Ltd. Wakayama Works (72) Inventor Kiyoshi Ichihara, 1850, Minato, Wakayama, Wakayama Sumitomo Metal Industries, Ltd. Wakayama Works
Claims (1)
により軸受鋼を製造する方法において、真空脱ガス処理
前の転炉内溶鋼に炭材およびCr合金鉄を投入し、さらに
転炉出鋼中にCaO-CaF2系合成スラグを添加し、真空処理
槽にて少なくとも30分以上継続して真空脱ガス処理を行
なうことを特徴とする軸受鋼の製造方法。1. A method for producing a bearing steel by a converter, a vacuum degassing process, and a continuous casting process, wherein carbonaceous material and Cr alloy iron are added to the molten steel in the converter before the vacuum degassing process, and the converter is discharged. A method for manufacturing a bearing steel, which comprises adding CaO-CaF 2 -based synthetic slag to steel and performing vacuum degassing treatment continuously in a vacuum treatment tank for at least 30 minutes or longer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63044952A JPH0645818B2 (en) | 1988-02-26 | 1988-02-26 | Bearing steel manufacturing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63044952A JPH0645818B2 (en) | 1988-02-26 | 1988-02-26 | Bearing steel manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01219118A JPH01219118A (en) | 1989-09-01 |
| JPH0645818B2 true JPH0645818B2 (en) | 1994-06-15 |
Family
ID=12705824
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63044952A Expired - Lifetime JPH0645818B2 (en) | 1988-02-26 | 1988-02-26 | Bearing steel manufacturing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0645818B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101925685B (en) * | 2008-07-30 | 2013-01-02 | 新日本制铁株式会社 | High-strength thick steel material and high-strength extra-thick H-shaped steel excellent in toughness and weldability, and their manufacturing method |
| CN105969932B (en) * | 2016-06-30 | 2018-04-06 | 山东钢铁股份有限公司 | A kind of method for making steel control hydrogen |
-
1988
- 1988-02-26 JP JP63044952A patent/JPH0645818B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01219118A (en) | 1989-09-01 |
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