JP3324272B2 - Manufacturing method of bearing steel - Google Patents

Manufacturing method of bearing steel

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Publication number
JP3324272B2
JP3324272B2 JP09511394A JP9511394A JP3324272B2 JP 3324272 B2 JP3324272 B2 JP 3324272B2 JP 09511394 A JP09511394 A JP 09511394A JP 9511394 A JP9511394 A JP 9511394A JP 3324272 B2 JP3324272 B2 JP 3324272B2
Authority
JP
Japan
Prior art keywords
slab
bearing steel
center segregation
continuous casting
reduction
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 - Fee Related
Application number
JP09511394A
Other languages
Japanese (ja)
Other versions
JPH07299550A (en
Inventor
公尊 衣川
嘉識 竹園
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daido Steel Co Ltd
Original Assignee
Daido Steel Co Ltd
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Filing date
Publication date
Application filed by Daido Steel Co Ltd filed Critical Daido Steel Co Ltd
Priority to JP09511394A priority Critical patent/JP3324272B2/en
Publication of JPH07299550A publication Critical patent/JPH07299550A/en
Application granted granted Critical
Publication of JP3324272B2 publication Critical patent/JP3324272B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【産業上の利用分野】本発明は連続鋳造による軸受鋼の
製造方法に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing bearing steel by continuous casting.

【0002】[0002]

【従来の技術】鋼の連続鋳造は歩留りがよく生産性が高
いという利点があるが、一方で鋳片の中心部にC,P,
Sなどの成分が偏析しやすいという欠点があるため、鋼
種によっては連続鋳造法の採用が困難である。 連続鋳
造が困難な代表は軸受鋼とくにSUJ2のような高炭素
高クロム軸受鋼であって、0.95〜1.10%という
高いC含有量に加えて製造品質に対する高い要求から、
従来は低速の連続鋳造品が軸受部品のうちレースおよび
コロを製造する材料に使用できるだけで、ボール用途に
向ける軸受鋼を連続鋳造により製造することは不可能と
されていた。
2. Description of the Related Art Continuous casting of steel has the advantage that the yield is high and the productivity is high, but C, P, and C are located at the center of the slab.
There is a drawback that components such as S tend to segregate, so that it is difficult to employ a continuous casting method depending on the type of steel. Representatives of which continuous casting is difficult are bearing steels, especially high carbon and high chromium bearing steels such as SUJ2, which have a high C content of 0.95 to 1.10% and a high demand for manufacturing quality.
Conventionally, low-speed continuous castings can only be used as materials for producing races and rollers among bearing components, and it has been impossible to continuously produce bearing steel for ball applications.

【0003】連続鋳造における中心偏析を抑制する手段
として、中心部の凝固に先立って低い圧下率でロール圧
を加える、いわゆる軽圧下が知られている。 軽圧下は
中心部の密着をよくする目的も含めて、しばしば行なわ
れている。
As a means for suppressing the center segregation in continuous casting, a so-called light reduction in which a roll pressure is applied at a low reduction ratio prior to solidification of a central portion is known. Light pressure reduction is often performed for the purpose of improving the close contact of the central part.

【0004】出願人は、この軽圧下による中心偏析の抑
制について研究を進め、鋳片を断面円形に鋳造するとと
もに、中心固相率が0.2〜0.8、好ましくは0.4
〜0.5の範囲にある間にフラットロールで軽圧下を加
えるとよいことを見出して、すでに提案した(特願平6
−15772号)。 軽圧下の度合は、圧下率にして1
〜3%程度が適当であることもわかった。
[0004] The applicant has conducted research on the suppression of center segregation due to this light reduction, casting a slab with a circular cross section, and having a center solid fraction of 0.2 to 0.8, preferably 0.4.
It has been found that it is preferable to apply a slight reduction with a flat roll while the pressure is in the range of 0.5 to 0.5, and has already proposed (Japanese Patent Application No. Hei 6 (1999)).
-15772). The degree of light reduction is 1
It has been found that about 3% is appropriate.

【0005】ここで「中心固相率」とは、鋳片の中心部
において固相が占める重量割合を意味する。 連続鋳造
により鋳片が形成される過程では、外側の完全に凝固し
たシェルと中心の液相だけの部分の間に、固相と液相の
混在した領域があり、その混相の存在する領域において
固相がどのくらいの割合を占めているかを示すのが、こ
の語である。 中心固相率は、鋳片の比熱、熱伝導率、
温湯温度等のデータをもとにした伝熱計算によって鋳片
断面温度分布を求め、それから推定する。
[0005] The term "central solid phase ratio" means the weight ratio of the solid phase in the center of the slab. In the process of forming a slab by continuous casting, there is a mixed region of solid phase and liquid phase between the outer completely solidified shell and the center liquid phase only part, and in the region where the mixed phase exists It is this term that indicates what percentage the solid phase occupies. The center solid fraction is the specific heat of the slab, the thermal conductivity,
The slab cross-section temperature distribution is obtained by heat transfer calculation based on data such as hot water temperature, and is estimated from that.

【0006】軸受鋼の鋳片は加熱炉に入れてソーキング
ののち、分塊圧延してビレットまたは製品とするが、ビ
レットの線材圧延に先立ってスカーフ処理すなわち火焔
キズ取りを必要としていた。 従来のソーキングは、鋳
片中に析出した巨大炭化物を基地中に溶解させ消失させ
ることを意図して、6時間程度の比較的長い時間行なっ
ていた。一方、ソーキングの間にブルームの表面では脱
炭が進むので、長時間のソーキングが生成させたスケー
ルとともに脱炭層を除去する必要があり、この理由から
もスカーフ処理は欠かせない。
[0006] The slab of the bearing steel is placed in a heating furnace, soaked, and then slab-rolled into a billet or a product. However, a scarf treatment, that is, a flame removal is required prior to the rolling of the billet wire. Conventional soaking has been performed for a relatively long time of about 6 hours, with the intention of dissolving and eliminating the giant carbide precipitated in the slab in the matrix. On the other hand, since decarburization proceeds on the surface of the bloom during soaking, it is necessary to remove the decarburized layer together with the scale generated by prolonged soaking, and for this reason also, the scarf treatment is indispensable.

【0007】[0007]

【発明が解決しようとする課題】本発明の目的は、出願
人の開発した上記の軽圧下技術を利用して高炭素軸受鋼
の鋳片を連続鋳造により製造すること、とくにボール用
の材料を連続鋳造で製造できるようにするとともに、レ
ース、コロ用の材料は従来より高速で鋳造できるように
し、しかもスカーフ処理の必要をなくした軸受鋼の製造
方法を提供することにある。
SUMMARY OF THE INVENTION It is an object of the present invention to produce a high carbon bearing steel slab by continuous casting using the above-described light reduction technology developed by the applicant, and in particular, to produce a ball material. It is an object of the present invention to provide a method of producing bearing steel that enables continuous casting, and that allows materials for races and rollers to be cast at a higher speed than before, and that eliminates the need for a scarf treatment.

【0008】[0008]

【課題を解決するための手段】本発明の軸受鋼の製造方
法は、連続鋳造による軸受鋼の製造において、垂直連続
鋳造法により断面が円形の鋳片を鋳造し、水冷鋳型から
引き出される鋳片に対してその中心凝固率が0.3〜
0.6である間に、フラットロールを用いて圧下率1〜
3%の軽圧下を加えて中心偏析を解消し、得られた鋳片
を温度1150〜1260℃に2〜5時間加熱するソー
キングを行なって分塊圧延することにより、スカーフ処
理をすることなく軸受部品に加工可能なビレットまたは
製品を得ることを特徴とする。
SUMMARY OF THE INVENTION The present invention relates to a method for producing bearing steel. In the production of bearing steel by continuous casting, a slab having a circular cross section is cast by a vertical continuous casting method and is drawn from a water-cooled mold. The central coagulation rate is 0.3 ~
While it is 0.6, the rolling reduction is 1 to 1 using a flat roll.
3% light reduction is applied to eliminate the center segregation, and the obtained slab is soaked at a temperature of 1150 to 1260 ° C. for 2 to 5 hours and slab-rolled, so that the bearing is not subjected to a scarf treatment. It is characterized by obtaining billets or products that can be processed into parts.

【0009】[0009]

【作用】以下、実例に即して本発明の上記構成が意味す
るところを説明する。 まず連続鋳造の鋳片の断面形状
を円形とすることは、前記したさきの特許出願に開示し
たように、溶鋼の凝固に伴う体積収縮を考慮に入れて軽
圧下の減面率と内部割れの可能性との関係を円形断面と
正方形断面とで比較すると、後者はコーナー部の引張応
力が大きく内部割れの危険が高いという事実にもとづ
く。 高炭素軸受鋼のように割れ感受性の強い材料は、
円形断面の鋳片を屈曲させずに引き出す垂直連鋳の方法
によるべきことになる。
Hereinafter, the meaning of the above-described configuration of the present invention will be described with reference to an actual example. First, as disclosed in the above-mentioned patent application, the cross-sectional shape of the slab of continuous casting is, as disclosed in the above-mentioned patent application, taking into account the volume shrinkage accompanying solidification of molten steel and the area reduction rate and the internal cracking under light pressure. Comparing the relationship with the possibility between a circular section and a square section, the latter is based on the fact that the tensile stress at the corners is large and the risk of internal cracking is high. Materials with strong crack sensitivity, such as high carbon bearing steel,
The method should be a vertical continuous casting method in which a slab having a circular cross section is drawn out without bending.

【0010】中心固相率がどの範囲のところで軽圧下を
行なうべきかについては、SUJ2鋼を対象に行なった
連続鋳造において、種々の位置で軽圧下した直径350
mmの円形断面をもつ鋳片(鋳造速度0.36m/min.)の
C中心偏析をしらべた図1の結果にもとづいて決定し
た。 「中心偏析」は、鋳片の中心部におけるC含有量
の、レードル中溶鋼のC含有量に対する比である。 図
1にみるように、C中心偏析の値は中心固相率fs が低
いところで、つまり鋳片内部で凝固が進まないうちに軽
圧下を実施したときに低くなる。 しかし、fs があま
り低いところで軽圧下した鋳片は内部割れが生じるの
で、0.3〜0.6の範囲で軽圧下を行なうべきことが
わかる。
Regarding the range where the center solid phase ratio should be reduced by light, the diameter of the lightly reduced 350 at various positions in continuous casting of SUJ2 steel was examined.
The C center segregation of a slab having a circular cross section of 0.3 mm (casting speed 0.36 m / min.) was determined based on the results of FIG. "Center segregation" is the ratio of the C content at the center of the slab to the C content of the molten steel in the ladle. As shown in FIG. 1, the value of C center segregation becomes low at a low center solid fraction f s , that is, when light reduction is performed before solidification progresses inside the slab. However, slab f s is soft reduction at too low is because the internal cracking occurs, it can be seen that should carry out the soft reduction in the range of 0.3 to 0.6.

【0011】最適の軽圧下位置は、この場合fs =0.
43の点であった。 この値は軸受鋼の組成、鋳片サイ
ズ、鋳造速度などの因子により多少は変動するが、それ
ぞれの場合に応じて容易に見出すことができよう。
The optimum light reduction position is, in this case, f s = 0.
43 points. This value varies somewhat depending on factors such as the composition of the bearing steel, the size of the slab, and the casting speed, but can be easily found in each case.

【0012】一般に、SUJ2鋼の場合、C中心偏析に
許容できる限界は、ボール用で1.1、レース・コロ用
で1.2とされている。 図1は、本発明によればこの
限界内の製品を得るのが容易であることを示している。
Generally, in the case of SUJ2 steel, the allowable limit of C center segregation is 1.1 for balls and 1.2 for race rollers. FIG. 1 shows that it is easy to obtain products within this limit according to the invention.

【0013】C中心偏析に及ぼす鋳造速度の影響は、図
2に示すとおりである。 SUJ2鋼を直径350mmの
円形鋳片に種々の鋳造速度で連続鋳造し、図1で知られ
た最適軽圧下位置(fs=0.43)において1.5%の
軽圧下を行なったところ、同じレベルのC中心偏析を達
成するのに、本発明に従う軽圧下を行なえば、より高い
鋳造速度を採用できることがわかった。 具体的には、
0.4m/minより低い鋳造速度ならばC中心偏析1.1
以下の鋳片が得られ、これは上記のように軸受のボール
の材料として使用可能である。 一方、C中心偏析の許
容限界をレース・コロ用の1.2まで拡大するならば、
0.4m/min以上に高めた鋳造速度が採用できる。 こ
れまでSUJ2鋼の連続鋳造の速度がレース・コロ用の
材料でさえ0.3m/minをほとんど超えられなかったこ
ととくらべれば、この鋳造速度の増大は大きな前進であ
る。
The effect of casting speed on C center segregation is as shown in FIG. The SUJ2 steel was continuously cast at different casting speeds circular slab with a diameter of 350 mm, was subjected to 1.5% of soft reduction in known optimal soft reduction position in Figure 1 (f s = 0.43), It has been found that higher casting speeds can be employed by performing the light reduction according to the present invention to achieve the same level of C center segregation. In particular,
If the casting speed is lower than 0.4 m / min, C center segregation 1.1
The following slabs are obtained, which can be used as a material for bearing balls as described above. On the other hand, if the allowable limit of C center segregation is expanded to 1.2 for race rollers,
A casting speed increased to 0.4 m / min or more can be adopted. This increase in casting speed is a big step forward, compared to the speed at which continuous casting of SUJ2 steel could hardly exceed 0.3 m / min even for race roller materials.

【0014】ソーキングに関しては、図3から前記条件
の採択理由がわかる。 直径350mmの円形断面の鋳片
に対し、軽圧下を行なわない場合、ソーキングにより巨
大炭化物を消失させるためには、図の細実線で示すノー
ズの範囲内、つまり1200〜1240℃程度の温度に
5〜6時間加熱することが必要とされていたが、本発明
に従って好適な軽圧下を加えた場合、ノーズは太実線で
示すように左へ移動し、短いソーキング時間においても
巨大炭化物のない材料となる。 図から明らかなよう
に、1150℃に達しないソーキング温度ではソーキン
グ時間短縮の効果がなく、一方、1260℃を超える高
い温度では、いったんは消失した巨大炭化物が再度晶出
して来る。 好ましい条件は、温度1200〜1240
℃、時間2.5〜3.0時間である。
Regarding soaking, FIG. 3 shows the reason for adopting the above conditions. When light reduction is not performed on a slab having a circular cross section with a diameter of 350 mm, in order to eliminate the giant carbide by soaking, it is necessary to maintain the temperature within the range of the nose shown by the thin solid line in the drawing, that is, at a temperature of about 1200 to 1240 ° C. Heating was required for up to 6 hours, but when a suitable light reduction was applied according to the present invention, the nose moved to the left as shown by the thick solid line, and even with a short soaking time, the material was free of giant carbide. Become. As is clear from the figure, at a soaking temperature of less than 1150 ° C., there is no effect of shortening the soaking time, while at a high temperature exceeding 1260 ° C., the once lost macro carbides crystallize again. Preferred conditions are temperatures from 1200 to 1240
° C, time 2.5-3.0 hours.

【0015】ソーキングに要する時間が短縮されれば、
前記したように、鋳片表面で脱炭が深く進行しないうち
に分塊圧延にかけることができるし、スケールの発生も
少なくて済む。 分塊圧延により得たブルームをさらに
圧延するに当りグラインダー研削による表面キズ取りを
行なうが、本発明に従って得たブルームの研削は表面の
限られた部分に対して行なえばよい。 それで、従来の
スカーフ処理と全面グラインダー研削をしたものと同じ
成績が得られる。
If the time required for soaking is reduced,
As described above, slab rolling can be performed before decarburization progresses deeply on the slab surface, and generation of scale can be reduced. When the bloom obtained by the bulk rolling is further rolled, surface scratches are removed by grinder grinding, but the bloom obtained according to the present invention may be ground only on a limited portion of the surface. Thus, the same results as those obtained by the conventional scarf treatment and the whole surface grinder grinding can be obtained.

【0016】[0016]

【発明の効果】以上のデータから明らかなように、本発
明に従って軸受鋼の製造を行なえば、高炭素軸受鋼を連
続鋳造しても中心偏析がゼロまたは僅少でボール用に向
けられる鋳片が容易に得られ、レース・コロ用の材料で
あれば従来より鋳造速度を高めても中心偏析が許容限度
内にあるものが得られる。
As is apparent from the above data, if the bearing steel is manufactured according to the present invention, even if the high carbon bearing steel is continuously cast, the slab which has no or little center segregation and is directed to the ball can be obtained. It is easy to obtain, and if it is a material for race rollers, even if the casting speed is higher than before, a material with center segregation within the allowable limit can be obtained.

【0017】鋳片の分塊圧延に先立つソーキングは従来
の半分程度の時間で足りるから、脱炭層が深くまで及ば
ない上にスケールの生成量も少ない。 従って表面は後
の圧延工程で圧延スケールとして脱落する程度であり、
スカーフ処理を行なわなくても、圧延などの加工工程に
送ることができる。
Since the soaking time before the slab rolling of the slab is about half the time required in the conventional method, the depth of the decarburized layer is not deep and the amount of scale generated is small. Therefore, the surface will fall off as a rolling scale in the subsequent rolling process,
Even without performing the scarf treatment, it can be sent to a processing step such as rolling.

【0018】このように、本発明は軸受鋼およびそれか
らの軸受製造の生産性を高め、コストを低下させる。
Thus, the present invention increases the productivity and reduces the cost of producing bearing steel and bearings therefrom.

【図面の簡単な説明】[Brief description of the drawings]

【図1】 本発明の実施データであって、SUJ2鋼を
円形断面の鋳片に鋳造する垂直連続鋳造において、軽圧
下の位置と鋳片のC中心偏析との関係を示すグラフ。
FIG. 1 is a graph showing the relationship between the position under light pressure and the C-center segregation of a slab in vertical continuous casting in which SUJ2 steel is cast into a slab having a circular cross section, which is implementation data of the present invention.

【図2】 図1に続く実施データであって、鋳造速度と
C中心偏析との関係を示すグラフ。
FIG. 2 is a graph showing the relationship between the casting speed and C center segregation, which is practical data following FIG.

【図3】 図2に続く実施データであって、鋳片の分塊
圧延に先立つソーキングに関し、種々の時間および温度
において鋳片中に巨大炭化物が存在するか否かを示すグ
ラフ。
FIG. 3 is a graph, following the data of FIG. 2, showing whether giant carbide is present in the slab at various times and temperatures for soaking prior to slab rolling of the slab.

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平3−254342(JP,A) 特開 昭63−215353(JP,A) 特開 平1−162551(JP,A) 特開 平5−228598(JP,A) 特開 昭63−123516(JP,A) 特開 平7−204812(JP,A) 特開 平6−33190(JP,A) 特開 平5−317091(JP,A) 特開 平3−254341(JP,A) 特開 平3−254340(JP,A) 特開 平3−254339(JP,A) 特開 平2−92444(JP,A) (58)調査した分野(Int.Cl.7,DB名) B22D 11/128 350 B22D 11/00 B22D 11/20 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-254342 (JP, A) JP-A-63-215353 (JP, A) JP-A-1-162551 (JP, A) JP-A-5-254 228598 (JP, A) JP-A-63-123516 (JP, A) JP-A-7-204812 (JP, A) JP-A-6-33190 (JP, A) JP-A-5-3177091 (JP, A) JP-A-3-254341 (JP, A) JP-A-3-254340 (JP, A) JP-A-3-254339 (JP, A) JP-A-2-92444 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) B22D 11/128 350 B22D 11/00 B22D 11/20

Claims (4)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】 連続鋳造による軸受鋼の製造において、
垂直連続鋳造法により断面が円形の鋳片を鋳造し、水冷
鋳型から引き出される鋳片に対して、その中心凝固率が
0.3〜0.6である間に、フラットロールを用いて圧
下率1〜3%の軽圧下を加えて中心偏析を解消し、得ら
れた鋳片を温度1150〜1260℃に2〜5時間加熱
するソーキングを行なって分塊圧延することにより、ス
カーフ処理をすることなくビレットまたは製品を得るこ
とを特徴とする軸受鋼の製造方法。
In the production of bearing steel by continuous casting,
A slab having a circular cross section is cast by a vertical continuous casting method, and a slab drawn from a water-cooled mold is subjected to a rolling reduction using a flat roll while its central solidification rate is 0.3 to 0.6. Applying a 1 to 3% light reduction to eliminate center segregation, subjecting the obtained slab to soaking by heating at a temperature of 1150 to 1260 ° C for 2 to 5 hours and subjecting it to sparf rolling to perform a scarf treatment A method for producing bearing steel, characterized in that a billet or a product is obtained without the need.
【請求項2】 軸受鋼が高炭素クロム軸受鋼SUJ1〜
5である請求項1の製造方法。
2. The bearing steel is high carbon chromium bearing steel SUJ1.
The method according to claim 1, wherein the number is 5.
【請求項3】 鋳造速度を0.3〜0.5m/minの範囲
で実施し、C中心偏析比1.2以下の鋳片を得る請求項
2の製造方法。
3. The method according to claim 2, wherein the casting speed is in the range of 0.3 to 0.5 m / min to obtain a slab having a C center segregation ratio of 1.2 or less.
【請求項4】 鋳造速度を0.3〜0.4m/secの範囲
で実施し、C中心偏析比1.1以下のボール用途に向け
得る鋳片を得る請求項2の製造方法。
4. The method according to claim 2, wherein the casting speed is set in the range of 0.3 to 0.4 m / sec to obtain a slab having a C center segregation ratio of 1.1 or less for use in balls.
JP09511394A 1994-05-09 1994-05-09 Manufacturing method of bearing steel Expired - Fee Related JP3324272B2 (en)

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Application Number Priority Date Filing Date Title
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JP3324272B2 true JP3324272B2 (en) 2002-09-17

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JP3367332B2 (en) * 1996-05-15 2003-01-14 日本鋼管株式会社 Manufacturing method of difficult-to-work seamless steel pipe
KR100446649B1 (en) * 2000-12-26 2004-09-04 주식회사 포스코 Method For Manufacturing Carbonitriding Bearing Steel
JP5229248B2 (en) * 2010-02-10 2013-07-03 新日鐵住金株式会社 Manufacturing method of bearing steel
KR101271899B1 (en) 2010-08-06 2013-06-05 주식회사 포스코 High carbon and chromium bearing steel and method for manufacturing the same
CN114054706B (en) * 2021-11-19 2023-04-25 河南济源钢铁(集团)有限公司 Production control method for improving pickling low-power quality of bearing steel round steel
CN114669724B (en) * 2022-03-31 2024-01-23 中天钢铁集团有限公司 Control method for producing large-size wind power bearing steel carbide by continuous casting and rolling process

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