JPS61117226A - Production of high-strength high-toughness hard steel wire - Google Patents

Abstract

PURPOSE:To obtain effectively a hard steel wire having high strength and high toughness by controlling a cooling rate according to the content of C in the stage of cooling a wire formed by rolling from a carbon steel with water and coiling thereof then subjecting the wire to controlled air cooling. CONSTITUTION:The hard steel wire contg. 0.40-0.85wt% C is cooled with water and is wound into a ring shape. The wound wire is subjected to the controlled air cooling in a force air cooling zone. The controlled air cooling is executed at 650 deg.C quick cooling limiting temp. and 25-35 deg.C/sec cooling rate when 0.60%<=C<=0.85%. The quick cooling limiting temp. is made 600 deg.C and the cooling is executed at a cooling rate of 25-40 deg.C/sec when 0.40%<=C<=0.60%. The cooling rate from the quick cooling limiting temp. down to 400 deg.C is set at 10-20 deg.C/sec regardless of the carbon content. The high-strength high- toughness hard steel wire for direct rolling which does not require a lead patenting treatment is stably obtd. by the above-mentioned method.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は高強度高靭性硬＃１ｉＩｌｓ材の製造方法に関
し、ピアノ線等の如き高強度で、靭性のすぐれた線材製
造分計で広く利用される。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a high-strength, high-toughness hard #1iIls material, and is widely used in the production of high-strength, high-toughness wires such as piano wires. be done.

〔従来の技術〕[Conventional technology]

従来広（実施されている線材の空冷熱処理とは仕上圧延
機通過後の線材が保有する約１ｏｏｏ℃の熱を利用し、
その冷却速度を制御して従来の鉛パテンイング（ＬＰ）
処理材と同程度の品質の線材を圧延工場で生産する方法
で、ステルモアの空冷処理と称せられているものは代表
的なものである。これを第４図によりｍ明する。仕上圧
延機２で圧延され線材４は水冷帯６で水冷され、ピンチ
ロール８、レイングヘッド１０でリング状に巻き取られ
強ＷＩＪ風冷却＠１２のコンベア１４上に展開され、ブ
ロワ１６により空冷されリフオーミングタブ１８により
収束される。この強制風冷却？１Ｆ１２における冷却は
「ステルモアの空冷処理」といわれる。このステルモア
の空冷処理により、製品の組織が大幅に変化することが
知られている。The conventional air-cooling heat treatment of wire rods utilizes the heat of approximately 100°C retained by the wire rods after passing through the finishing mill.
Conventional lead patterning (LP) by controlling its cooling rate
Stelmore's air-cooling process is a typical method for producing wire rods of the same quality as the treated material at a rolling mill. This is illustrated in FIG. The wire rod 4 rolled by the finishing mill 2 is water-cooled in the water-cooling zone 6, wound up into a ring shape by the pinch rolls 8 and the laying head 10, spread on the conveyor 14 with strong WIJ wind cooling @ 12, and air-cooled by the blower 16. It is converged by the reforming tab 18. This forced air cooling? The cooling in 1F12 is called "Stellmor air cooling process." It is known that this air cooling treatment of Stelmore significantly changes the structure of the product.

特にＪＩＳの硬＃１１４１材（ＳＷＲ）（）　、ピアノ
線材（ＳＷＲ３）等の硬＃４線材はユーザーにおけろ伸
線時の強度を確保するために、線材製品で高張力、高靭
性が要求される。従ってオーステナイトから常温までの
冷却速度を制御し、最終組織を微細なフェライト−パー
ライト組織とすることが必要となる。In particular, hard #4 wires such as JIS hard #1141 material (SWR) () and piano wire (SWR3) require high tensile strength and high toughness in wire products to ensure strength during wire drawing by users. be done. Therefore, it is necessary to control the cooling rate from austenite to room temperature to make the final structure a fine ferrite-pearlite structure.

これは一段的に炭素鋼の連続冷却変態（以下ＣＣＴと称
する）曲線を用いて説明することが可能で、これを第５
図に示したが、空冷後の最終組織を微細なフェライト−
パーライトとするためには、マルテンサイトの発生しな
い上限冷却速度以下で、なおかつパーライトが粗大化し
ない下限冷却速度以上で冷却する必要がある。This can be explained in a step by using the continuous cooling transformation (hereinafter referred to as CCT) curve of carbon steel, and this
As shown in the figure, the final structure after air cooling is a fine ferrite structure.
In order to form pearlite, it is necessary to cool at an upper limit cooling rate at which martensite does not occur and at a lower limit cooling rate at which pearlite does not become coarse.

従って従来は特公昭４２−１５４６３号に示されている
ように恒温変態として理想的な鉛パテンテイング（ＬＰ
）処理に対し、上記の考え方により冷却速度を決定して
強制風冷による冷却方法が用いられているが、これには
次の如き問題点がある。Therefore, as shown in Japanese Patent Publication No. 42-15463, lead patenting (LP), which is ideal for isothermal transformation, has been
), a cooling method using forced air cooling is used in which the cooling rate is determined based on the above concept, but this method has the following problems.

（Ａ）　　強制風冷却帯１２の各区分ごとの長さが長く
、コンベア１４上で冷却速度を変化させようとしても冷
却能力が不足し、一定の冷却となり、任意の冷却速度を
得ることができない。(A) The length of each section of the forced air cooling zone 12 is long, and even if an attempt is made to change the cooling rate on the conveyor 14, the cooling capacity is insufficient, resulting in constant cooling, making it impossible to obtain an arbitrary cooling rate. .

（Ｂ）　　各ブロアー１６の冷却能力が小さく、特に空
冷初期における能力が不十分であり、必要とする初期冷
却ができない。(B) The cooling capacity of each blower 16 is small, especially in the initial stage of air cooling, and the required initial cooling cannot be achieved.

従って、製造される硬鋼線材等の品質には従来法の１ｇ
ＩＷ！点があった。Therefore, the quality of manufactured hard steel wire rods, etc. is limited to 1g by the conventional method.
IW! There was a point.

（イ）強冷範囲の区分の選択が不適切であゆ、品種によ
ってはマルテンサイトの発生による靭性ａ−低下が見ら
れる。(a) The selection of the strong cooling range classification is inappropriate, and depending on the product, a decrease in toughness a- is observed due to the formation of martensite.

（ν）　同様に弱冷範囲の区分数が不適切で広くなると
パーライトの粗大化による引張強さの劣化を生じろ。(ν) Similarly, if the number of divisions in the weak cooling range is inappropriate and wide, the tensile strength will deteriorate due to coarsening of pearlite.

（Ａ）初期急冷が不十分なため、品種によっては結晶粒
が微細化されず引張強さが向上しない。(A) Due to insufficient initial quenching, depending on the product, crystal grains may not be refined and tensile strength may not be improved.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

本発明の目的は上記従来技術の問題点を解決し、冷却速
度を制御することにより高強度高靭性硬鋼線材の効果的
な製造方法を提供するにある。An object of the present invention is to solve the problems of the prior art described above and to provide an effective method for producing a high-strength, high-toughness hard steel wire by controlling the cooling rate.

〔問題点を解決するための手段および作用〕本発明の要
旨とするところは次の如くである。[Means and operations for solving the problems] The gist of the present invention is as follows.

すなわち、重量比でＣ：０．４０〜０．８５％を含有し
仕上圧延機で圧延された線材を水冷帯で水冷しリング状
に巻取る段階と、前記巻き取られた線材を強制風冷却帯
で展開して制御風冷する段階と、を有して成る硬鋼線材
の製造方法において、前記制御風冷を炭素含有量に応じ
て下記第１表に示す冷却速度で冷却することを特徴とす
る高強度高靭性硬鋼線材の製造方法である。That is, a wire rod containing 0.40 to 0.85% C by weight and rolled in a finishing mill is water-cooled in a water cooling zone and wound into a ring shape, and the wound wire rod is forced-air cooled. A method for producing a hard steel wire comprising the steps of expanding it in a band and performing controlled air cooling, characterized in that the controlled air cooling is performed at a cooling rate shown in Table 1 below depending on the carbon content. This is a method for producing a high-strength, high-toughness hard steel wire rod.

第１表 本発明者らはステルモアの空冷処理について種々検討し
空冷モデルの解析結果から判断して次の方法により高強
度で高靭性の線材を製造できることを見い出した。Table 1 The present inventors conducted various studies on the air cooling treatment of Stelmore, and judging from the analysis results of the air cooling model, they found that a wire rod with high strength and high toughness can be manufactured by the following method.

（Ａ）　　仕上圧延によし圧延された線材を巻取後、共
析変態までの冷却速度をマルテンサイト変態が発生しな
い範囲で大としてオーステナイトを過用し共析変態濃度
を降下させることにより強度低下の原因となる一次フエ
ライトの析出を抑え、同時にパーライト発生の際の核生
成サイトを分散させ組織の微細化を図る。(A) After winding the wire rod that has been finished rolled, the cooling rate until eutectoid transformation is increased to the extent that martensitic transformation does not occur, and austenite is used excessively to lower the eutectoid transformation concentration, thereby reducing the strength. It suppresses the precipitation of primary ferrite, which causes pearlite, and at the same time disperses the nucleation sites when pearlite occurs, resulting in a finer structure.

（ＢＪ　　共析変態後の冷却は主として最終組織の結晶
粒度調整により均一化を図るために上記（幻に比し、冷
却速度を低下させ除冷する。(BJ Cooling after the eutectoid transformation is performed by slowing down the cooling rate and gradually cooling it, compared to the above (illusion), in order to achieve uniformity mainly by adjusting the crystal grain size of the final structure.

本発明で使用するステル上１線材冷却装置を第１図によ
り説明する。第４図で説明した従来装置と同一もしくは
相当部分の説明は省略するが強制風冷却帯１２は従来が
６区分であるのに対し、第１図で示す本発明装置では１
２区分（ＩＡ、ＩＢ・・・・・・ＭＡ、ＶＩＢ）に細分
され、それに従ってブロ７１６も増強されａＩ数も倍増
され冷却能力を強化されている。A single wire cooling device on a stell used in the present invention will be explained with reference to FIG. Although the description of the same or equivalent parts as in the conventional device explained in FIG. 4 will be omitted, the conventional forced air cooling zone 12 has six sections, whereas in the device of the present invention shown in FIG.
It is subdivided into two sections (IA, IB, . . . MA, VIB), and accordingly the blower 716 is also strengthened, the number of aI is doubled, and the cooling capacity is strengthened.

本発明は第１図に示した装置でコンベアエ４に展開され
た線材を強制風冷却を行うが、炭素含有量を０．４０〜
０．８５％の範囲に限定したのは次の理由による。すな
わち、Ｃが０．４０％未満でば風冷効果が現われず高強
度が得られなく、また反対にＣが０．８５％を越すと高
強度は得られるものの靭性が劣化するので、本発明では
Ｃ：　ｏ、　４０〜０．８５％の線材を使用することと
した。The present invention uses the apparatus shown in FIG. 1 to perform forced air cooling on the wire spread out on the conveyor 4.
The reason for limiting the range to 0.85% is as follows. That is, if the C content is less than 0.40%, the wind cooling effect will not appear and high strength will not be obtained.On the other hand, if the C content exceeds 0.85%, although high strength will be obtained, the toughness will deteriorate. In C: o, we decided to use a 40 to 0.85% wire rod.

本発明においては急冷限界温度を越える温度まで急冷す
るが、これは炭素の含有量により異なる。In the present invention, quenching is performed to a temperature exceeding the quenching limit temperature, but this varies depending on the carbon content.

すなわち、炭素含有量の多い鋼種ではマルテンサイトの
発生限界が低冷却速度側へ移行する。従って適冷による
オーステナイト域の拡大が発生する場合でも、急冷限界
温度Ｔ、ば０．６０％≦Ｃ≦０．８５％ではＴＬ　＝６
５０℃、０．４０％≦Ｃく００６０％ではＴ、＝６００
℃が限界であり、これ以下まで急冷するとマルテンサイ
トが発生する。That is, in steel types with a high carbon content, the limit of martensite generation shifts to the lower cooling rate side. Therefore, even if the austenite region expands due to proper cooling, if the quenching limit temperature T is 0.60%≦C≦0.85%, TL = 6.
At 50℃, 0.40%≦C0060%, T = 600
℃ is the limit, and if it is rapidly cooled below this temperature, martensite will occur.

次に急冷限界温度Ｔｔを越える温度における冷却速度は
０．６０％≦Ｃ≦０＃８５％の場合、２５〜ｂ すとオーステナイトの適冷限界濃度が６５０℃未満まで
拡がり、反面工程生産時には断面方向の鋼材温度勾配等
Ｈｒよる不均一から核生成が不均一となるので最終組織
が不均一となり、一部がマルテンサイトになる場合もあ
り、絞り値が低下する。Next, when the cooling rate at a temperature exceeding the quenching limit temperature Tt is 0.60%≦C≦0#85%, the appropriate cooling limit concentration of austenite expands to less than 650°C. Since nucleation becomes non-uniform due to non-uniformity due to Hr such as the steel material temperature gradient in the direction, the final structure becomes non-uniform, and a part of the structure may become martensite, resulting in a decrease in the reduction of area.

また２５℃／Ｓ未満では従来法と同一となり本発明の目
的が達成されない。これらの理由から急冷限界温度を越
える温度域の冷却速度を２５〜ｂの範囲に限定した。Moreover, if it is less than 25° C./S, it will be the same as the conventional method and the object of the present invention will not be achieved. For these reasons, the cooling rate in the temperature range exceeding the quenching limit temperature was limited to a range of 25 to b.

次に０．４０％≦Ｃ＜０．６０％の場合の冷却速度につ
いても同様な傾向にあるが、含有炭素量が少ないのでマ
ルテンサイト発生限界の冷却速度も高炭素の場合に比し
大きくすることが可能のため、高速側を拡大して２５〜
ｂ た。Next, the cooling rate in the case of 0.40%≦C<0.60% has a similar tendency, but since the amount of carbon contained is small, the cooling rate at the limit of martensite generation is also higher than in the case of high carbon. Since it is possible to enlarge the high speed side and
b.

急冷限界温度を炭素の含有量に応じて６００℃もしくは
６５０℃を越える濃度域に限定したが、実際に急冷を停
止する急冷停止温度はこの急冷限界温度を大きく上まわ
らないのが望ましい。Although the quenching limit temperature is limited to a concentration range exceeding 600°C or 650°C depending on the carbon content, it is desirable that the quenching stop temperature at which quenching is actually stopped does not greatly exceed this quenching limit temperature.

次に急冷限界温度から４００℃までの冷却速度は炭素含
有量に関係なく、フェライト−パーライト組織の成長を
均一１と行わせるため１０〜ｂの冷却速度で冷却する必
要がある。２０℃／Ｓを越えると細粒化し、１０℃／Ｓ
未満では粗粒化し適当な粒度が得られないので冷却速度
を１０〜ｂの範囲に限定した。また、２次冷却の下限を
４００℃に限定したのは４００℃未満では変態も完了し
結晶粒の成長もほぼ完了しているため冷却速度を限定す
る必要がないからである。Next, the cooling rate from the quenching limit temperature to 400° C. must be 10 to 10 b in order to uniformly grow the ferrite-pearlite structure, regardless of the carbon content. When the temperature exceeds 20℃/S, the particles become fine, and when the temperature exceeds 10℃/S
The cooling rate was limited to a range of 10 to b because if it is less than 1, the particles become coarse and an appropriate particle size cannot be obtained. Further, the lower limit of the secondary cooling is set to 400°C because the transformation is completed and the growth of crystal grains is almost completed below 400°C, so there is no need to limit the cooling rate.

第２図に本発明法と従来法における強制風冷却帯の線材
の冷却状態を比較して概念的に示したが、急冷限界温度
を越える温度域まで急冷するのに、従来法においては第
４図で示す強制風冷却帯の半分の第夏区分まで必要であ
ったが、本発明法においては冷却能力が増加したので、
短時間に急冷することが可能になった。Figure 2 conceptually shows a comparison of the cooling state of the wire in the forced air cooling zone between the method of the present invention and the conventional method. Although half of the forced air cooling zone shown in the figure was required in the summer section, the method of the present invention has increased cooling capacity.
It became possible to rapidly cool the product in a short period of time.

第３図はＣ：０．５５％の場合における本発明法と従来
法を００７曲線で比較して示しているが、本発明法は従
来法に比較して短時間側で変態を修了した後、有効な除
冷を行うことにより、鉛パテンテイング（ＬＰ）処理に
接近していることがわかる。Figure 3 shows a 007 curve comparing the method of the present invention and the conventional method in the case of C: 0.55%. , it can be seen that by performing effective slow cooling, it approaches lead patenting (LP) treatment.

本発明は上記の如くステル上１線材冷却装置を使用して
、Ｃ：０．４０〜０．８５％の硬鋼線材を使用して、鉛
パテンテイング処理を省略した直接伸線用の高強度、高
靭性硬１１４＃Ｉ材を安定して製造することができろ。As described above, the present invention uses a single wire cooling device on the stell, and uses a hard steel wire rod with C: 0.40 to 0.85% to provide high strength wire rods for direct wire drawing without lead patenting treatment. It would be possible to stably produce high-toughness hard 114#I material.

〔実施例〕〔Example〕

第２表に成分を示した径５．５ｍｍの３種の供試材を冷
却速度を変えて直接空冷熱処理を行った。Three types of test materials with diameters of 5.5 mm whose components are shown in Table 2 were subjected to direct air cooling heat treatment at different cooling rates.

すなわち、本発明実施例は強制風冷却帯の１区分長さ４
．５ｍであり最大冷却速度４０℃／Ｓの装置で第３表に
示す冷却速度で冷却した。That is, in the embodiment of the present invention, the length of one section of the forced air cooling zone is 4.
．． It was cooled at the cooling rate shown in Table 3 using an apparatus with a length of 5 m and a maximum cooling rate of 40° C./S.

従来例は強＄１１風冷却帯の１区分の長さが９ｍの装置
において第３表の条件で冷却したが、冷却能力が低いの
で急冷には強制風冷却帯の大半を必要とした。In the conventional example, cooling was performed under the conditions shown in Table 3 in an apparatus in which the length of one section of the strong $11 wind cooling zone was 9 m, but since the cooling capacity was low, most of the forced wind cooling zone was required for rapid cooling.

また、比較例として他の装置を使用して最大冷却速度を
４０℃／Ｓまで冷却能力を強化した装置で、第３表の条
件によって冷却した場合も併せ記載した。In addition, as a comparative example, a case in which cooling was performed under the conditions shown in Table 3 using another device in which the cooling capacity was enhanced to a maximum cooling rate of 40° C./S is also described.

これらの供試材の引張強さおよび絞りを調査しその結果
を第３表に示した。The tensile strength and area of area of these test materials were investigated and the results are shown in Table 3.

９３表から、本発明実ｍｆＰ４ば、急冷停止濃度もしく
は急冷速度が本発明の条件を満足しない従来例に比し引
張強さが２〜Ｓ　ｋｇ　／　ｗｍ　”すぐれ、急冷速度
の大なる比較例に比較しても、なお絞りが２〜４％向上
していることがわかる。From Table 93, the actual mfP4 of the present invention has a tensile strength of 2 to S kg/wm, which is superior to the conventional example whose quenching stop concentration or quenching rate does not satisfy the conditions of the present invention, making it a comparative example with a large quenching rate. Even when compared, it can be seen that the aperture is still improved by 2 to 4%.

〔発明の効果〕〔Effect of the invention〕

本発明は上記実施例からも明らかな如く、硬鋼線材の製
造方法において、炭素含有量に応じて、急冷限界温度を
設定し、急冷中と急冷後の冷却速度を限定する制御風冷
を行うことによって鉛パテンイングを行うことなく高強
度高靭性のすぐれた硬Ｗ４線材を製造することができた
。As is clear from the above embodiments, the present invention is a method for manufacturing hard steel wire rods, in which a quenching limit temperature is set according to the carbon content, and controlled air cooling is performed to limit the cooling rate during and after quenching. As a result, it was possible to produce a hard W4 wire with excellent strength and toughness without performing lead patterning.

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

第１図は本発明で使用するステルモア線材冷却装置を示
す模式配置図、第２図は本発明法と従来法におけろ強制
風冷却帯における線材の冷却状態を概念的に示した線図
、第３図は本発明法と従来法とを比較して示した連続冷
却変態曲線、第４図は従来のステルモア線材冷却装置の
模式配置図、第５図は炭素鋼の連続冷却変態曲線である
。Fig. 1 is a schematic layout diagram showing the Stelmore wire cooling device used in the present invention, Fig. 2 is a diagram conceptually showing the cooling state of the wire in the forced air cooling zone in the method of the present invention and the conventional method. Figure 3 is a continuous cooling transformation curve comparing the method of the present invention and the conventional method, Figure 4 is a schematic layout of a conventional Stelmore wire cooling device, and Figure 5 is a continuous cooling transformation curve of carbon steel. .

Claims (1)

【特許請求の範囲】[Claims] （１）重量比でＣ：０．４０〜０．８５％を含有し仕上
圧延機で圧延された線材を水冷帯で水冷しリング状に巻
取る段階と、前記巻取られた線材を強制風冷却帯で展開
して制御風冷する段階と、を有して成る硬鋼線材の製造
方法において、前記制御風冷を炭素含有量に応じて下記
第１表に示す冷却速度で冷却することを特徴とする高強
度高靭性硬鋼線材の製造方法。 第１表 ▲数式、化学式、表等があります▼(1) A step in which a wire rod containing 0.40 to 0.85% C by weight and rolled in a finishing mill is water-cooled in a water-cooling zone and wound into a ring shape, and the wound wire rod is subjected to forced winding. A method for manufacturing a hard steel wire comprising the steps of expanding in a cooling zone and cooling with controlled air, the controlled air cooling being performed at a cooling rate shown in Table 1 below depending on the carbon content. A method for producing high-strength, high-toughness hard steel wire. Table 1▲Contains mathematical formulas, chemical formulas, tables, etc.▼