JPH0849016A - Production of high carbon steel with fine pearlitic structure - Google Patents
Production of high carbon steel with fine pearlitic structureInfo
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- JPH0849016A JPH0849016A JP6182666A JP18266694A JPH0849016A JP H0849016 A JPH0849016 A JP H0849016A JP 6182666 A JP6182666 A JP 6182666A JP 18266694 A JP18266694 A JP 18266694A JP H0849016 A JPH0849016 A JP H0849016A
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はレール、形鋼、棒鋼その
他の産業機械に広く使われる靭性および延性の高い高炭
素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 high carbon steel having high toughness and ductility which is widely used in rails, shaped steel, steel bars and other industrial machines.
【０００２】[0002]
【従来の技術】高炭素でパーライトの金属組織を呈した
鋼は強度が高く、耐摩耗性が良好なことから構造材料と
して使用され、中でも鉄道車両の重量増加に伴う高軸荷
重化や高速輸送化に対応してレールに特に多く使用され
ている。2. Description of the Related Art Steel with a high carbon and pearlite metallographic structure is used as a structural material because it has high strength and good wear resistance. Corresponding to the trend, it is especially often used for rails.
【０００３】このような鋼材の製造法としては、例え
ば、特開昭５８−２２１２２９号公報には「Ｃ：０．６
５〜０．８５％、Ｍｎ：０．５％〜２．５％を含有した
高温Ｍｎ鋼レールをオーステナイト領域から急冷し、レ
ールまたはレールヘッドの組織を微細なパーライトとし
て耐摩耗を改善したレールの熱処理方法」、特開昭５９
−１３３３２２号公報には「安定してパーライト組織が
得られる特定成分の圧延レールをＡｒ3 点以上の温度か
ら特定温度の溶融塩浴中に浸漬して、レール頭頂部表面
下約１０mmまでＨｖ＞３５０の硬さを持つ微細なパーラ
イト組織を呈するレールの熱処理方法」、特開昭６３−
２７７７２１号公報には「制御圧延と加熱処理を組み合
わせた製造方法および圧延後の低温加熱処理方法として
８００℃以下で断面減少率が５％以上の圧延を行い、７
５０〜９００℃へ加熱し、１〜１５℃／秒で加速冷却す
るレール鋼の製造方法」が開示されているがごとく、多
くの技術が知られている。As a method of manufacturing such a steel material, for example, Japanese Patent Laid-Open No. 58-212229 discloses "C: 0.6.
A high-temperature Mn steel rail containing 5 to 0.85% and Mn: 0.5% to 2.5% is rapidly cooled from the austenite region, and the structure of the rail or rail head is used as fine pearlite to improve wear resistance. Heat treatment method ", JP-A-59
JP-A-133322 discloses, "A rolling rail of a specific component capable of stably obtaining a pearlite structure is immersed in a molten salt bath at a temperature of Ar 3 or higher to a specific temperature and Hv> about 10 mm below the surface of the top of the rail head. Heat treatment method for rails having a fine pearlite structure having a hardness of 350 ", JP-A-63-
JP-A-277721 discloses, "As a manufacturing method combining controlled rolling and heat treatment and a low-temperature heat treatment method after rolling, rolling with a cross-section reduction rate of 5% or more at 800 ° C. or less is performed.
Many techniques are known, as is disclosed in "A manufacturing method of rail steel in which heating is performed at 50 to 900 ° C and accelerated cooling is performed at 1 to 15 ° C / sec".
【０００４】しかしながら、パーライト鋼の強度や耐摩
耗性は合金元素の添加によって所要の規格品のレールが
容易に得られるとは言え、靭性はフェライト組織を主体
とした鋼に比較して著しく低く、例えばパーライトレー
ル鋼ではＪＩＳ３号Ｕノッチシャルピー試験での常温試
験値で１〜２kgfm／cm2 程度である。このように靭性の
低い鋼を繰り返し荷重や振動のかかる分野で構造部材と
して使用した場合、微小な初期欠陥や疲労き裂から低応
力脆性破壊を引き起こす問題があった。However, although the strength and wear resistance of pearlite steel can be easily obtained by adding an alloying element to the rail of the required standard product, the toughness is remarkably lower than that of steel mainly composed of ferrite structure, For example, for pearlite rail steel, the room temperature test value in the JIS No. 3 U notch Charpy test is about 1 to 2 kgfm / cm 2 . When such a steel having low toughness is used as a structural member in a field where repeated load or vibration is applied, there is a problem in that low stress brittle fracture is caused by minute initial defects and fatigue cracks.
【０００５】一般に、高炭素鋼の靭性を向上させる手段
には金属組織の細粒化、つまりオーステナイト組織の細
粒化や粒内変態によって達成されている。このうち、粒
内変態は制御が難しく、オーステナイト組織の細粒化が
靭性の向上のかぎとなっている。とくに、γ粒度７番を
超えて、好ましくは８番以上に微細化すれば、ＪＩＳ３
号Ｕノッチシャルピー試験での常温試験値で２．５kgfm
／cm2 程度が出現することが本発明者らの実験でわかっ
た。In general, the means for improving the toughness of high carbon steel is achieved by refining the metal structure, that is, refining the austenite structure and intragranular transformation. Of these, intragranular transformation is difficult to control, and the refinement of the austenite structure is the key to improving toughness. In particular, if the size of γ grain exceeds 7 and preferably 8 or more, JIS3
No. U Notch Charpy test at room temperature 2.5kgfm
It was found from the experiments conducted by the present inventors that about / cm 2 appears.
【０００６】特開昭６３−２７７７２１号公報にはパー
ライト変態を利用して金属組織を細粒化する技術が延べ
られているが、これには実際の圧延における仕上げ圧延
温度域である８５０〜１０５０℃の範囲での加工歪量は
検討されていない。また、この温度領域での微細なオー
ステナイトを得るための最適な加工温度と加工量につい
て検討したものは他にも見あたらない。Japanese Unexamined Patent Publication (Kokai) No. 63-277721 discloses a technique for refining the metal structure by utilizing pearlite transformation, which includes a finishing rolling temperature range of 850 to 1050. The amount of processing strain in the range of ° C has not been examined. Further, no other study has examined the optimum processing temperature and processing amount for obtaining fine austenite in this temperature range.
【０００７】[0007]
【発明が解決しようとする課題】本発明は、目標となる
γ粒度に対し、仕上げ圧延における適切な温度と加工量
を与え、効率的にかつ目標としている組織である微細パ
ーライト組織をもった高炭素鋼を生産することを目的と
している。DISCLOSURE OF THE INVENTION The present invention provides a target γ grain size with an appropriate temperature and working amount in finish rolling, efficiently and with a fine pearlite structure which is a target structure. The purpose is to produce carbon steel.
【０００８】[0008]
【課題を解決するための手段】本発明の要旨は、Ｃ：
０．６〜１．０％を含有する炭素鋼または低合金鋼の鋼
片を熱間粗圧延した中間成形材を、表面温度が８５０〜
１０５０℃でかつ、図１（ａ）で示され下記の回帰式
で求められる加工温度−粒界再結晶粒度番号曲線の、最
終目標γ粒度を得られる加工温度に加熱または冷却し、
続いて図１（ｂ）で示され下記回帰式で求められる加
工温度−粒界再結晶歪曲線の、該仕上げ圧延温度から読
み取れる加工歪で、最終製品形状に仕上げ圧延すること
を特徴とする微細なパーライト組織を呈する高炭素鋼の
製造方法である。 Ｔ＝−５０×Ｎ＋１３８０±３０・・・・・・・・・・・・・・・・・・・・ Ｔ：加工温度℃，Ｎ：目標γ粒径 ｅ＝−０．００２×Ｔ＋２．１５±０．０４・・・・・・・・・・ ｅ：加工歪 本発明者らは、細粒のパーライト組織を得て靭性を向上
させた鋼を効率的に製造するために多くの実験を実験室
と実生産設備とで試みた。この実験結果と考察により以
下に本発明について詳細に説明する。SUMMARY OF THE INVENTION The gist of the present invention is C:
An intermediate formed material obtained by hot rough rolling a billet of carbon steel or low alloy steel containing 0.6 to 1.0% has a surface temperature of 850 to
At 1050 ° C., heating or cooling is performed at a processing temperature at which the final target γ grain size of the processing temperature-grain boundary recrystallization grain size number curve shown in FIG.
Subsequently, the processing temperature can be read from the finishing rolling temperature of the processing temperature-grain boundary recrystallization strain curve shown in FIG. It is a method for producing a high carbon steel exhibiting a perfect pearlite structure. T = −50 × N + 1380 ± 30 ... T: processing temperature C, N: target γ grain size e = −0.002 × T + 2.15 ± 0.04 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ e: Working strain The present inventors conducted many experiments in order to efficiently obtain a steel having a fine grained pearlite structure and improved toughness. Tried in a laboratory and a real production facility. The present invention will be described in detail below based on the experimental results and consideration.
【０００９】最初に、本発明において鋼成分を上記のよ
うに限定した理由を説明する。通常の溶解炉で溶製され
た溶鋼を連続鋳造法あるいは造塊分塊法の工程を経て製
造された炭素鋼片、あるいはさらにＣｒ，Ｍｏ，Ｖ，Ｎ
ｉなどの強度靭性向上元素を少量含有した低合金鋼片に
おいては、Ｃはパーライト金属組織を生成させ、とくに
レール用鋼として耐摩耗性を向上させるために有効な成
分であり、この組織を得るために０．６０％以上を含有
させる必要がある。しかし、１．００％を超える過剰な
量を含有させることはセメンタイト金属組織が多く析出
して硬さを増加させるが、延性を低下させる。そこで、
本発明におけるＣ量は０．６％〜１．０％に限定した。First, the reason why the steel composition is limited as described above in the present invention will be explained. Carbon steel slab produced by continuous casting method or ingot-agglomeration method of molten steel melted in an ordinary melting furnace, or further Cr, Mo, V, N
In a low alloy steel slab containing a small amount of an element for improving strength and toughness such as i, C is an effective component for producing a pearlite metallographic structure and particularly improving the wear resistance as steel for rails, and this structure is obtained. Therefore, it is necessary to contain 0.60% or more. However, if an excessive amount exceeding 1.00% is contained, a large amount of cementite metal structure precipitates and the hardness increases, but the ductility decreases. Therefore,
The C content in the present invention is limited to 0.6% to 1.0%.
【００１０】次に粗圧延について述べる。上記のように
製造された鋼片は加熱後にレール形状に粗圧延される。
しかし、仕上げ圧延で高圧下しても粗圧延の後で非常に
粗大化した結晶粒では最終的に微細な組織は得られず、
また、仕上げ圧延工程での温度の自由度をもたせる必要
もある。そこで、好ましくは、粗圧延の最終パスの温度
は１０００℃以上、１１００℃以下であることが望まし
い。Next, rough rolling will be described. The steel slab produced as described above is roughly rolled into a rail shape after heating.
However, even if a high pressure is applied in the finish rolling, a fine structure cannot be finally obtained with crystal grains that have become extremely coarse after rough rolling,
In addition, it is necessary to have a degree of freedom of temperature in the finish rolling process. Therefore, it is preferable that the temperature of the final pass of the rough rolling is 1000 ° C. or higher and 1100 ° C. or lower.
【００１１】次いで、仕上げ圧延について述べる。粗圧
延された熱鋼片は引き続いて仕上げ圧延を施される。表
面温度で温度を限定した理由は実際の加工や実験で内部
の温度が測定できないことや、靭性として最も重要とさ
れる箇所が必ずしも内部の深いところとは限らないから
である。この８５０〜１０５０℃の範囲に限定した理由
は粒界近傍で再結晶が生じるが、粒成長がさほど問題と
ならない範囲だからである。Next, finish rolling will be described. The rough rolled hot billet is subsequently subjected to finish rolling. The reason why the temperature is limited by the surface temperature is that the internal temperature cannot be measured in actual processing or experiments, and the toughness that is most important is not necessarily the deep inside. The reason for limiting the temperature range to 850 to 1050 ° C. is that recrystallization occurs near the grain boundaries, but grain growth is not a problem.
【００１２】さらに、仕上げ加工条件の決定方法につい
て説明する。高炭素鋼の細粒γ組織を得るには、加工と
それに引き続く再結晶を繰り返し生じさせなければなら
ない。。本発明者らは実験的に高炭素鋼の静的再結晶の
粒径が加工温度にほぼ依存していることと、その際の再
結晶する場所のほとんどが旧結晶粒界にあることを見い
だした。Further, a method of determining finishing processing conditions will be described. In order to obtain a fine-grained γ structure of high carbon steel, processing and subsequent recrystallization must be repeated. . The present inventors have experimentally found that the grain size of static recrystallization of high carbon steel is almost dependent on the processing temperature, and that most of the recrystallization sites at that time are at the old grain boundaries. It was
【００１３】まず、加工温度を決定する。図１（ａ）は
上記実験の結果から加工温度と粒界での再結晶粒度の関
係曲線を得たものである。この曲線が加工温度−粒界再
結晶粒度曲線であり、この線はほぼ直線的であったの
で、回帰式を求め、次の式が得られる。この式を用い
て再結晶する前の結晶粒界の近傍で目標γ粒径を得るた
めの加工温度が得られる。 Ｔ＝−５０×Ｎ＋１３８０±３０・・・・・・・・・・・・・・・・・・・・ Ｔ：加工温度℃，Ｎ：目標γ粒径First, the processing temperature is determined. FIG. 1A shows a relationship curve between the processing temperature and the recrystallized grain size at the grain boundary obtained from the results of the above experiment. This curve is the processing temperature-grain boundary recrystallization particle size curve, and since this line was almost linear, a regression equation was obtained and the following equation was obtained. Using this formula, the processing temperature for obtaining the target γ grain size near the grain boundary before recrystallization can be obtained. T = −50 × N + 1380 ± 30 ... T: processing temperature C, N: target γ grain size
【００１４】次にこのときの加工量を決定する。加工量
と温度を変化させる実験を行い、粒界のほとんどが再結
晶する領域を明らかにし、この領域と粒界のほとんどが
再結晶しない領域との境界線を加工温度−加工歪関係曲
線と定義する。図１（ｂ）はこうして得られた加工温度
−粒界再結晶歪曲線である。この曲線もほぼ直線的であ
るので、回帰式を求め、次の式が得られた。加工温度
がすでに決定しているので、加工歪はこの式を用いて得
られる。 ｅ＝−０．００２×Ｔ＋２．１５±０．０４・・・・・・・・・・ ｅ：加工歪Next, the processing amount at this time is determined. We conducted an experiment to change the working amount and temperature, and clarified the region where most of the grain boundaries recrystallized, and defined the boundary line between this region and the region where most of the grain boundaries did not recrystallize as the working temperature-working strain relationship curve. To do. FIG. 1B is a processing temperature-grain boundary recrystallization strain curve thus obtained. Since this curve is also almost linear, a regression equation was obtained and the following equation was obtained. Since the processing temperature has already been determined, the processing strain is obtained using this formula. e = −0.002 × T + 2.15 ± 0.04 ... e: Processing strain
【００１５】粒界の部分のみが再結晶するので、加工前
の旧結晶粒径が再結晶した新しい結晶粒径の２倍より大
きければ混粒となる。逆に旧結晶粒の径が再結晶してで
きた新しい結晶粒径の２倍の径より小さければ整粒組織
になり得る。２倍の粒径の差は結晶粒度にして２番の差
である。そこで、粗圧延後の中間成形材の粒度より最終
目標γ粒度を２番以上細かくしたいときは中間の粒径の
整粒組織を得ることにし、それ以上細かくしたいときは
中間の粒径の整粒組織をさらにもう一段階得れば良い。
この中間の粒度を加工前必要粒度と定義する。ここで加
工前必要粒度は上記の理由により目標とするγ粒度より
１〜２番粗い粗度とする。実際に粒度を２番細かくする
のは結晶粒の成長によって難しいので、好ましくは、１
〜１．５番程度が望ましく、また、現実的である。この
加工前必要粒度を得るのも目標粒度を得るのと同じ方法
で加工温度と加工歪を決定し、加工する。Since only the grain boundaries are recrystallized, if the old crystal grain size before processing is larger than twice the recrystallized new crystal grain size, mixed grains are formed. On the contrary, if the diameter of the old crystal grains is smaller than twice the diameter of the new crystal grains formed by recrystallization, a grain-sized structure can be obtained. The difference in the grain size which is twice as large is the second difference in grain size. Therefore, when it is desired to make the final target γ grain size finer than the grain size of the intermediate molded material after rough rolling by 2 or more, a grain size control structure with an intermediate grain size is obtained. You just need to get the organization one more step.
This intermediate grain size is defined as the required grain size before processing. Here, the required grain size before processing is one to two coarser than the target γ grain size for the above reason. Since it is difficult to actually make the grain size finer by the growth of crystal grains, it is preferable that the grain size be 1
It is desirable and realistic that the number is about 1.5. In order to obtain the required grain size before processing, the processing temperature and processing strain are determined and processed in the same manner as in obtaining the target particle size.
【００１６】そこで好ましくは、最終目標粒度番号と中
間成形材の粒度番号との差が２番以上のとき、最終仕上
げ圧延の前に、該加工温度−粒界再結晶粒度番号曲線
の、最終目標粒度番号より１〜２番粗い粒度を得る加工
温度に、該鋼片を加熱または冷却し、続いて該加工温度
−再結晶歪曲線の該仕上げ圧延温度で求められる加工歪
で、最終仕上げ前圧延することが望ましい。Therefore, preferably, when the difference between the final target grain size number and the grain size number of the intermediate molding material is 2 or more, before the final finish rolling, the final target of the processing temperature-grain boundary recrystallization grain size number curve. The steel slab is heated or cooled to a processing temperature at which a grain size 1 to 2 is coarser than the grain size number, and then the pre-final finishing rolling is performed at a working strain determined by the finishing rolling temperature of the processing temperature-recrystallization strain curve. It is desirable to do.
【００１７】また、好ましくは、最終目標粒度番号と中
間成形材の粒度番号との差が４番以上のとき、最終仕上
げ圧延と仕上げ前圧延の前に、該加工温度−最終目標粒
度番号関係曲線の、最終目標γ粒度より２〜４番粗い粒
度を得る加工温度に、加熱または冷却し、続いて該仕上
げ圧延温度で該加工温度−再結晶歪曲線の加工歪で、、
圧延して製造することが望ましい。Further, preferably, when the difference between the final target grain size number and the grain size number of the intermediate molding material is 4 or more, the processing temperature-final target grain size number relationship curve is obtained before the final finish rolling and the pre-finish rolling. Heating or cooling to a processing temperature to obtain a grain size 2 to 4 coarser than the final target γ grain size, and then at the finishing rolling temperature-the processing strain of the recrystallization strain curve,
It is desirable to manufacture by rolling.
【００１８】実際の圧延工程で加工歪は断面減少率に換
算されなければならない、断面減少率は公称歪と真歪の
換算にすぎず、次の式で簡単に求められる。 γ＝｛１−ｅｘｐ（−ｅ）｝×１００ γ：断面減少率％，ｅ：加工歪 逆に、加工歪は上記の式で断面減少率から定義されるも
のである。In the actual rolling process, the work strain must be converted into a cross-section reduction rate. The cross-section reduction rate is merely a conversion between the nominal strain and the true strain, and can be easily obtained by the following formula. [gamma] = {1-exp (-e)} * 100 [gamma]: area reduction rate%, e: processing strain Conversely, the processing strain is defined from the area reduction rate in the above equation.
【００１９】仕上げ圧延では最終形状が精密に要求さ
れ、加工歪が１パスでとれないほど大きい場合も想定さ
れる。加工歪が０．２（断面減少率１８％）より大きい
とき複雑な形状が正確には製造しにくく、好ましくは、
０．１５（断面減少率１４％）以下でないと精密な形状
は望めない。しかし、その加工歪は多パスに分割しても
再結晶できることが実験的に分かった。ただし、そのパ
ス間時間は１０秒が限界で、それ以上長くなると回復が
生じるので、再結晶が生じない。好ましくは、６秒以下
にすると回復が十分行われず、再結晶がしやすい。そこ
で好ましくは、仕上げ圧延の加工量が０．１５より大き
くしなければならない場合、パス間時間１０秒以内の多
パスに分割して製造することが望ましい。なお、粒成長
を抑えるために時間を取らず、好ましくは、パス間の冷
却は水冷等の急冷が望ましい。In the finish rolling, the final shape is required to be precise, and it is assumed that the processing strain is too large to be removed in one pass. When the processing strain is larger than 0.2 (cross-section reduction rate 18%), it is difficult to manufacture a complicated shape accurately.
If it is not more than 0.15 (14% reduction in area), a precise shape cannot be expected. However, it was experimentally found that the processing strain can be recrystallized even if it is divided into multiple passes. However, the time between passes is limited to 10 seconds, and if it is longer than that, recovery occurs, so that recrystallization does not occur. Preferably, when the time is 6 seconds or less, recovery is not sufficiently performed and recrystallization is easy. Therefore, preferably, when the amount of finish rolling has to be greater than 0.15, it is desirable to manufacture by dividing into multiple passes with a time between passes of 10 seconds or less. In order to suppress grain growth, no time is taken, and it is preferable that the cooling between passes is rapid cooling such as water cooling.
【００２０】最後に図２を利用した加工温度と加工量の
決定方法を示す。図２は３パスで目標粒度を得る場合を
示している。 加工直後の目標γ粒度を決める。 目標粒度より１〜２番粗い粒度を加工前必要粒度とし
て決め、必要に応じてこれの更なる加工前必要粒度を決
める。 目標γ粒度及び加工前必要粒度を図１（ａ）の横軸に
とる。 目標γ粒度及び加工前必要粒度を得る加工温度を図１
（ａ）から読みとる。 で得た加工温度を（ｂ）の縦軸にとる。 必要となる加工歪を（ｂ）の横軸から読みとる。 加工歪から断面減少率を計算する。Finally, a method of determining the processing temperature and the processing amount using FIG. 2 will be shown. FIG. 2 shows a case where the target grain size is obtained by three passes. Determine the target γ grain size immediately after processing. A grain size 1 to 2 coarser than the target grain size is determined as a required grain size before processing, and a further required grain size before processing is determined if necessary. The target γ grain size and the required grain size before processing are plotted on the horizontal axis of FIG. Figure 1 shows the processing temperature to obtain the target γ particle size and the required particle size before processing.
Read from (a). The processing temperature obtained in step (b) is plotted on the vertical axis. The required processing strain is read from the horizontal axis of (b). Calculate the area reduction rate from the work strain.
【００２１】[0021]
［実施例−１］ γ結晶粒度９番を得たい場合 図３（ａ），（ｂ）は図１（ａ），（ｂ）を実施例１の
解説用にしたものである。このときの中間成形材のγ粒
度は４．６であった。目標粒度が９であり、４以上の粒
度差があるので、加工前必要粒度を７．８、さらにこの
加工前必要粒度を６．６とした。これらから図３（ａ）
より加工温度を読みとるとそれぞれ９３０℃、９９０
℃、１０５０℃である。これらからさらに、図３（ｂ）
より加工温度を読みとるとそれぞれ、０．２９、０．１
７、０．０５となる。０．２９の歪を最終パスでとれな
いので、０．１５ずつ２パスのタンデム圧延にする。こ
れを断面減少率に換算するとそれぞれ１３．９％２パ
ス、１５．６％、４．９％となる。[Example-1] When it is desired to obtain γ crystal grain size 9 FIGS. 3A and 3B are obtained by explaining FIGS. 1A and 1B for Example 1. At this time, the γ grain size of the intermediate molded material was 4.6. Since the target grain size is 9 and there is a grain size difference of 4 or more, the required grain size before processing was set to 7.8, and the required grain size before processing was set to 6.6. From these, Fig. 3 (a)
If you read the processing temperature more, 930 ℃, 990 respectively
C., 1050.degree. From these, further, FIG.
If you read the processing temperature more, 0.29 and 0.1 respectively
It becomes 7, 0.05. Since a strain of 0.29 cannot be taken in the final pass, tandem rolling is performed in two passes of 0.15. Converting this into a cross-section reduction rate results in 13.9% 2-pass, 15.6% and 4.9%, respectively.
【００２２】したがって、この場合の仕上げ圧延は次の
ようなスケジュールとなる。 最終：９３０℃、加工歪０．２９、タンデム２パス１
３．９％ずつ 最終より２パス目：９９０℃、加工歪０．１７、１５．
６％ 最終より３パス目：１０５０℃、加工歪０．０５、４．
９％Therefore, the finish rolling in this case has the following schedule. Final: 930 ° C, processing strain 0.29, tandem 2 pass 1
Second pass from the end by 3.9%: 990 ° C., processing strain 0.17, 15.
6% 3rd pass from the end: 1050 ° C., processing strain 0.05, 4.
9%
【００２３】このスケジュールの圧延は軌条製造用の孔
型圧延で実施した。冷却手段は目標温度近くまでを高圧
水の噴霧、目標温度近くなってからを空冷で行った。タ
ンデムのパス間は５秒間とした。この時使用した鋼材の
成分は、単位ｗｔ％で、Ｃ：０．７９、Ｓｉ：０．５
６、Ｍｎ：１．０７、Ｐ：０．０１７、Ｓ：０．０１
１、Ｖ：０．０９、Ｃｒ：０．２２、残部Ｆｅおよび不
可避的不純物である（実施例２〜４も同じ）。このよう
なスケジュールで圧延を行い、圧延出側で急冷し、γ粒
度を測定した結果、９．０のγ粒度が得られた。Rolling according to this schedule was carried out as a hole rolling for rail production. As the cooling means, high-pressure water was sprayed up to near the target temperature, and air cooling was performed after reaching the target temperature. The time between tandem passes was 5 seconds. The composition of the steel material used at this time is C: 0.79, Si: 0.5 in the unit of wt%.
6, Mn: 1.07, P: 0.017, S: 0.01
1, V: 0.09, Cr: 0.22, balance Fe and unavoidable impurities (the same applies to Examples 2 to 4). As a result of rolling on such a schedule, rapid cooling on the rolling-out side, and measurement of γ grain size, a γ grain size of 9.0 was obtained.
【００２４】［実施例−２］ γ結晶粒度９．５番を得
たい場合 図４（ａ），（ｂ）は図１（ａ），（ｂ）を実施例２の
解説用にしたものである。このときの中間成形材のγ粒
度は４．６であった。目標粒度が９．５であり、４以上
の粒度差があるので加工前必要粒度を８．１、さらにこ
の加工前必要粒度を６．６とした。実施例１と同様に図
４からパススケジュールを読みとると、次のようにな
り、これは最終パスを３パスのタンデムで行うこととし
た。また、実施例１と同様に冷却手段は目標温度近くま
でを高圧水の噴霧、目標温度近くなってからを空冷で行
った。 最終：９０５℃、加工歪０．３４、タンデム３パス１
３．９％、１３．９％、３．９％ 最終から２パス目：９７５℃、加工歪０．２、１８．１
％ 最終から３パス目：１０５０℃、加工歪０．０５、４．
９％ このようなスケジュールで圧延を行い、圧延出側で急冷
し、γ粒度を測定した結果、９．５のγ粒度が得られ
た。[Example 2] When it is desired to obtain a γ crystal grain size of 9.5, FIGS. 4 (a) and 4 (b) are obtained by explaining FIGS. 1 (a) and 1 (b) in Example 2. is there. At this time, the γ grain size of the intermediate molded material was 4.6. Since the target grain size is 9.5 and there is a grain size difference of 4 or more, the required grain size before processing was set to 8.1, and the required grain size before processing was set to 6.6. When the pass schedule is read from FIG. 4 as in the first embodiment, the result is as follows, and it is decided that the final pass is performed in tandem of 3 passes. Further, as in Example 1, the cooling means sprayed high-pressure water up to near the target temperature and air-cooled after reaching the target temperature. Final: 905 ° C, processing strain 0.34, tandem 3 pass 1
3.9%, 13.9%, 3.9% Second pass from the end: 975 ° C, work strain 0.2, 18.1
% 3rd pass from the last: 1050 ° C., processing strain 0.05, 4.
9% Rolling was carried out on such a schedule, quenching was performed on the rolling-out side, and γ grain size was measured. As a result, a γ grain size of 9.5 was obtained.
【００２５】［実施例−３］ γ結晶粒度８．５番を得
たい場合 図５（ａ），（ｂ）は図１（ａ），（ｂ）を実施例３の
解説用にしたものである。このときの中間成形材のγ粒
度は４．６であった。目標粒度が８．５であり、２以上
の粒度差があるので、加工前必要粒度を７．０とした。
実施例１と同様に図５からパススケジュールを読みとる
と、次のようになった。これも最終パスを２パスタンデ
ムに分けて行うこととした。また、実施例１と同様に冷
却手段は目標温度近くまでを高圧水の噴霧、目標温度近
くなってからを空冷で行った。 最終：９５５℃、加工歪０．２４、タンデム１１．３
％、２パスずつ 最終から２パス目：１０３０℃、加工歪０．０９、８．
６％ このようなスケジュールで圧延を行い、圧延出側で急冷
し、γ粒度を測定した結果、８．４のγ粒度が得られ
た。[Embodiment 3] When it is desired to obtain a γ crystal grain size of 8.5, FIGS. 5 (a) and 5 (b) are obtained by explaining FIGS. 1 (a) and 1 (b) to explain Embodiment 3. is there. At this time, the γ grain size of the intermediate molded material was 4.6. Since the target grain size is 8.5 and there is a grain size difference of 2 or more, the required grain size before processing was set to 7.0.
When the pass schedule was read from FIG. 5 as in Example 1, the result was as follows. This is also done by dividing the final pass into two pass tandems. Further, as in Example 1, the cooling means sprayed high-pressure water up to near the target temperature and air-cooled after reaching the target temperature. Final: 955 ° C, processing strain 0.24, tandem 11.3
%, 2 passes each, 2nd pass from the last: 1030 ° C., processing strain 0.09, 8.
6% Rolling was carried out on such a schedule, quenching was performed on the rolling-out side, and γ grain size was measured. As a result, a γ grain size of 8.4 was obtained.
【００２６】［実施例−４］ γ結晶粒度８．０番を得
たい場合 図６（ａ），（ｂ）は図１（ａ），（ｂ）を実施例４の
解説用にしたものである。このときの中間成形材のγ粒
度は４．６であった。目標粒度が８．０であり、２以上
の粒度差があるので加工前必要粒度を６．６とした。実
施例１と同様に図６からパススケジュールを読みとる
と、次のようになった。また、実施例１と同様に冷却手
段は目標温度近くまでを高圧水の噴霧、目標温度近くな
ってからを空冷で行った。 最終：９８０℃、加工歪０．１９、１７．３％ 最終から２パス目：１０５０℃、加工歪０．０５、４．
９％ このようなスケジュールで圧延を行い、圧延出側で急冷
し、γ粒度を測定した結果、７．８のγ粒度が得られ
た。[Embodiment 4] When it is desired to obtain a gamma grain size of 8.0, FIGS. 6 (a) and 6 (b) are obtained by explaining FIGS. 1 (a) and 1 (b) to explain Embodiment 4. is there. At this time, the γ grain size of the intermediate molded material was 4.6. Since the target grain size is 8.0 and there is a grain size difference of 2 or more, the required grain size before processing was set to 6.6. When the pass schedule was read from FIG. 6 as in Example 1, the result was as follows. Further, as in Example 1, the cooling means sprayed high-pressure water up to near the target temperature and air-cooled after reaching the target temperature. Final: 980 ° C., processing strain 0.19, 17.3% Second pass from the end: 1050 ° C., processing strain 0.05, 4.
9% Rolling was performed on such a schedule, rapid cooling was performed on the rolling-out side, and γ grain size was measured. As a result, a γ grain size of 7.8 was obtained.
【００２７】[0027]
【発明の効果】以上説明したように、本発明を実施する
ことにより、加工コストを抑えてかつ目標とした微細パ
ーライト組織を持った高炭素鋼を得ることができるよう
になった。またこのことで、γ粒度７番を超えたものが
安定して得られ、靭性および延性の高い炭素鋼を得るこ
とができるようになった。As described above, by carrying out the present invention, it becomes possible to obtain a high carbon steel having a target fine pearlite structure while suppressing the processing cost. Further, as a result, it is possible to stably obtain a steel having a γ grain size of more than 7, and to obtain a carbon steel having high toughness and ductility.
【図１】パススケジュールを決定するための線図であっ
て、（ａ）は加工温度−最終目標粒度番号関係曲線、
（ｂ）は加工温度−加工歪関係曲線を示す。FIG. 1 is a diagram for determining a pass schedule, in which (a) is a processing temperature-final target grain size number relationship curve,
(B) shows a processing temperature-processing strain relationship curve.
【図２】パススケジュールを決定するための線図（３パ
スで目標粒度を得る場合）であって、（ａ）は加工温度
−最終目標粒度番号関係曲線、（ｂ）は加工温度−加工
歪関係曲線を示す。FIG. 2 is a diagram for determining a pass schedule (when a target grain size is obtained by three passes), (a) is a machining temperature-final target grain size number relation curve, and (b) is a machining temperature-machining strain. The relationship curve is shown.
【図３】実施例１のパススケジュールを決定するための
線図（γ粒度９番を得たい場合）であって、（ａ）は加
工温度−最終目標粒度番号関係曲線、（ｂ）は加工温度
−加工歪関係曲線を示す。FIG. 3 is a diagram for determining a pass schedule of Example 1 (when it is desired to obtain γ grain size 9), (a) is a machining temperature-final target grain size number relation curve, and (b) is machining. The temperature-working strain relationship curve is shown.
【図４】実施例２のパススケジュールを決定するための
線図（γ粒度９．５番を得たい場合）であって、（ａ）
は加工温度−最終目標粒度番号関係曲線、（ｂ）は加工
温度−加工歪関係曲線を示す。FIG. 4 is a diagram for determining a pass schedule according to the second embodiment (when it is desired to obtain a γ grain size of 9.5);
Shows a processing temperature-final target grain size number relationship curve, and (b) shows a processing temperature-processing strain relationship curve.
【図５】実施例３のパススケジュールを決定するための
線図（γ粒度８．５番を得たい場合）であって、（ａ）
は加工温度−最終目標粒度番号関係曲線、（ｂ）は加工
温度−加工歪関係曲線を示す。FIG. 5 is a diagram for determining a path schedule of Example 3 (when it is desired to obtain a γ grain size of 8.5), (a)
Shows a processing temperature-final target grain size number relationship curve, and (b) shows a processing temperature-processing strain relationship curve.
【図６】実施例４のパススケジュールを決定するための
線図（γ粒度８．０番を得たい場合）であって、（ａ）
は加工温度−最終目標粒度番号関係曲線、（ｂ）は加工
温度−加工歪関係曲線を示す。FIG. 6 is a diagram for determining a path schedule of Example 4 (when it is desired to obtain a γ grain size of 8.0);
Shows a processing temperature-final target grain size number relationship curve, and (b) shows a processing temperature-processing strain relationship curve.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｂ２１Ｂ 1/16 Ｂ 37/00 ＢＢＧ // Ｃ２１Ｄ 9/00 １０２ Ａ 9352−4Ｋ 9/04 Ａ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI Technical display location B21B 1/16 B 37/00 BBG // C21D 9/00 102 A 9352-4K 9/04 A
Claims (1)
または低合金鋼の鋼片を熱間粗圧延した中間成形材を、
表面温度が８５０〜１０５０℃でかつ、下記の回帰式
で求められる加工温度−粒界再結晶粒度番号曲線の、最
終目標γ粒度を得られる加工温度に加熱または冷却し、
続いて下記回帰式で求められる加工温度−粒界再結晶
歪曲線の、該仕上げ圧延温度から読み取れる加工歪で、
最終製品形状に仕上げ圧延することを特徴とする微細な
パーライト組織を呈する高炭素鋼の製造方法。 Ｔ＝−５０×Ｎ＋１３８０±３０・・・・・・・・・・・・・・・・・・・・ Ｔ：加工温度℃，Ｎ：目標γ粒径 ｅ＝−０．００２×Ｔ＋２．１５±０．０４・・・・・・・・・・ ｅ：加工歪1. An intermediate formed material obtained by hot rough rolling a carbon steel or low alloy steel billet containing C: 0.6 to 1.0%,
A surface temperature is 850 to 1050 ° C., and heating or cooling is performed at a processing temperature obtained by the following regression equation-grain boundary recrystallization grain size number curve to a processing temperature at which a final target γ grain size is obtained,
Subsequently, the processing temperature obtained by the following regression equation-grain boundary recrystallization strain curve, the processing strain read from the finish rolling temperature,
A method for producing a high carbon steel having a fine pearlite structure, characterized by finish rolling into a final product shape. T = −50 × N + 1380 ± 30 ... T: processing temperature C, N: target γ grain size e = −0.002 × T + 2.15 ± 0.04 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ e: Processing strain
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6182666A JPH0849016A (en) | 1994-08-03 | 1994-08-03 | Production of high carbon steel with fine pearlitic structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6182666A JPH0849016A (en) | 1994-08-03 | 1994-08-03 | Production of high carbon steel with fine pearlitic structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0849016A true JPH0849016A (en) | 1996-02-20 |
Family
ID=16122316
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6182666A Withdrawn JPH0849016A (en) | 1994-08-03 | 1994-08-03 | Production of high carbon steel with fine pearlitic structure |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0849016A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6928737B2 (en) * | 1999-12-16 | 2005-08-16 | Nsk Ltd. | Wheel-support rolling bearing unit and a method manufacturing the same |
-
1994
- 1994-08-03 JP JP6182666A patent/JPH0849016A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6928737B2 (en) * | 1999-12-16 | 2005-08-16 | Nsk Ltd. | Wheel-support rolling bearing unit and a method manufacturing the same |
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