JP2005226147A - Stainless steel wire manufacturing method - Google Patents

Stainless steel wire manufacturing method Download PDF

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JP2005226147A
JP2005226147A JP2004037819A JP2004037819A JP2005226147A JP 2005226147 A JP2005226147 A JP 2005226147A JP 2004037819 A JP2004037819 A JP 2004037819A JP 2004037819 A JP2004037819 A JP 2004037819A JP 2005226147 A JP2005226147 A JP 2005226147A
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stainless steel
rolling
wire
temperature
cr
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Takufumi Hayashi
Yoshiyuki Shibata
琢文 林
佳幸 柴田
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Daido Steel Co Ltd
大同特殊鋼株式会社
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Abstract

PROBLEM TO BE SOLVED: To provide a ferritic stainless steel wire manufacturing method for manufacturing a product having cold workability substantially not different from that of conventional heat-treated products even when the heat treatment after rolling the wire is omitted and the manufacturing cost is reduced.
SOLUTION: Wires of ferritic stainless steel containing ≤ 0.10% C are rolled at a temperature equal to or lower than the γ transformation point but ≥ 700°C, and gradually cooled at a cooling rate of 0.3°C/sec. (the temperature transition as shown by the plot of black squares in the figure). Thus, rolling is completed while avoiding deposition of martensite, and production of a Cr-depleted layer can also be avoided. As a result, a flexible wire product can be obtained, in which the tensile strength is reduced, and the drawing value is enhanced.
COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、ステンレス鋼、とくにフェライト系ステンレス鋼の線材を製造する方法に関する。 The present invention is stainless steel, to a method particularly for producing a wire of the ferritic stainless steel.

ステンレス鋼、とくに13〜19%のCrを含有するフェライト系ステンレス鋼から線材を製造する工程においては、熱間圧延ののち、必ず熱処理および酸洗を行なう。 Stainless steel, in the step of producing a wire from a ferritic stainless steel containing in particular 13 to 19% of Cr, after the hot rolling is performed always heat treatment and pickling. 圧延におけるポイントは、製品の外観および品質を良好にするため、材料を比較的高い温度に加熱し、圧延中の温度を常に950〜1100℃程度に保ち、圧延後は空冷する、という手順が一般に採用されている。 Points in rolling, in order to improve the appearance and quality of the products, heating the material to a relatively high temperature, the temperature during rolling always maintained at about 950-1100 ° C., after rolling to cooling, procedure is generally called It has been adopted. 温度の推移を、加熱炉からの抽出にはじまって、初段−中段−終段の圧延段階まで追うと、図1に白抜き丸のプロットで示したようになる。 The transition temperature, starting the extraction from the heating furnace, the first stage - middle - the follow up rolling phase the final stage, becomes as shown in the plot of white circles in FIG.

熱間圧延により製造した線材は、多くの場合、冷間で伸線してそのまま、またはさらに加工を加えて最終製品にすることが多く、冷間引き抜き、曲がり矯正などの処理を受ける。 Wire produced by hot rolling is often as it is drawn cold, or further processed in addition often to a final product, drawing cold, subjected to processing such as straightening. こうした冷間の加工に当たって、割れや折損を生じることのない線材を製造することを企てた出願人は、フェライト系ステンレス鋼の組織を結晶粒度6以上の細粒とすべきこと、それが、熱間圧延速度を調節して圧延終止温度を800〜930℃の範囲にすれば実現することを知り、すでに開示した(特許文献1)。 When processing between these cold, applicants attempted to be produced that no wire causing cracking and breakage, it should be a structure of ferrite stainless steel with grain size 6 or more fine grains, it, know that by adjusting the hot rolling speed to achieve if the rolling termination temperature in the range of eight hundred to nine hundred and thirty ° C., already disclosed (Patent Document 1).
特開2002−167619 Patent 2002-167619

いうまでもなく熱処理はコストのかかる工程であるから、なるべく簡略化または省略したい。 Since mention heat treatment is a process costly want as much as possible simplified or omitted. しかし、熱処理を行なわなければ、圧延材は硬すぎて、伸線などの冷間加工に適しないものになる。 However, to be performed heat treatment, the rolled material is too hard, the ones not suitable for cold working such as wire drawing. 代表的なフェライト系ステンレス鋼であるSUS430についていえば、望ましい冷間加工性を得るには、引張り強さが540N/mm 2以下、絞りが60%以上という軟らかさをもつことが要求される。 As for a typical ferritic stainless steel SUS430, in order to obtain the desired cold workability, tensile strength of 540N / mm 2 or less, the diaphragm is required to have a softness of 60% or more.

本発明の目的は、フェライト系ステンレス鋼線材の製造において、線材圧延後の熱処理を省略しても、熱処理したものと実質上違わない冷間加工性を有する製品を製造する方法を提供することにある。 An object of the present invention, in the manufacture of ferritic stainless steel wire, be omitted heat treatment after wire rolling, to provide a method for producing a product having a heat treated ones with substantially no different cold workability is there.

上記の目的を達成する本発明のステンレス鋼線材の製造方法は、C含有量0.10%以下のフェライト系ステンレス鋼を、700℃以上であってγ変態点以下の温度において線材圧延し、0.3℃/秒以下の冷却速度で徐冷することからなる。 Method for producing a stainless steel wire of the present invention to achieve the above object, the C content 0.10% of the ferritic stainless steel, and rolled wire at 700 ° C. or higher in an in γ transformation point temperature, 0 It consists of annealing in the following cooling rate .3 ° C. / sec. 本発明に従う圧延の一例について温度の推移を追うと、図1に黒角のプロットで示したような経過をたどり、圧延の開始時と終止時とで、温度はほとんど変わらない。 When follow changes in temperature of an example of rolling according to the present invention, follows a course as shown in the plot of black square in Figure 1, in a time of end and at the beginning of rolling, the temperature hardly changes.

本発明の方法に従ってステンレス鋼線材を製造すれば、圧延の間γ変態点以下の温度が維持されているから、マルテンサイトの析出を避けて圧延を完了することができる。 Be manufactured of stainless steel wire in accordance with the method of the present invention, because the temperature below the transformation point γ between rolling is maintained, it is possible to complete the rolling avoid the precipitation of martensite. 圧延後は徐冷することにより、クロムの炭化物Cr 236の析出が少なく、かつ、比較的高い温度が維持されている間にCrが拡散するので、Cr欠乏層の生成を避けることができる。 By after the rolling is slow cooling, less precipitation of carbides Cr 23 C 6 chromium, and because Cr is diffused while relatively high temperatures are maintained, it is possible to avoid the formation of Cr-depleted layer . その結果、引張り強さが低下し、絞り値は向上する上、耐食性の向上も期待できる。 As a result, the tensile strength is lowered, the aperture value is on the increase, improvement in the corrosion resistance can be expected. 従来の圧延方法によるときは、マルテンサイトの析出が不可避であり、圧延に続く熱処理が必要であったが、本発明により、熱処理は不要になった。 When the conventional rolling method, precipitation of martensite is unavoidable, but the heat treatment following the rolling was needed, the present invention, heat treatment is no longer needed. これにより工程の簡略化とコストの低減が可能になった。 This enabled to reduce the simplification and cost process.

Fe−17%Crの系において、炭素量と温度とにより決定される相をサーモカルクにより状態図に画くと、図2のようになる。 In the system of Fe-17% Cr, the draw phase determined by the carbon content and temperature in the phase diagram by Samokaruku, it is as shown in FIG. この図から、γ変態点は、940℃近辺にあると推定される。 From this figure, gamma transformation temperature is estimated to be near 940 ° C.. 従来の比較的高い加熱温度を採用した圧延は、図2の破線で囲んだ領域において行なわれていたものであるが、本発明の圧延は、実線で囲んだ領域において行なうことになる。 Rolling that employs a conventional relatively high heating temperature, but is what was done in the area surrounded by a broken line in FIG. 2, the rolling of the present invention will be carried out in a region surrounded by a solid line. C:0.10%という上限は、α単相ではなく、α+γの二相域を設けるC量、という理由で設けたものである。 C: upper limit of 0.10% is not a alpha single phase, C content providing two-phase region of alpha + gamma, those provided on the grounds that. この限界内のC含有量で0.03%を超える比較的高炭素の鋼も、ほぼ940℃以下の温度で加熱炉から抽出し圧延することにより、マルテンサイトの析出を避けて圧延することができる。 Relatively high carbon steel of greater than 0.03% in C content in this limit, by extracting rolling from the furnace at approximately 940 ° C. temperature below be rolled to avoid the precipitation of martensite it can. C含有量0.03%以下の低炭素の鋼は、基本的にα単相の圧延が可能である。 C content more than 0.03% of the low-carbon steels, it is possible to rolling essentially α single phase.

従来の高温で行なう圧延は、フェライト(α)+オーステナイト(γ)の混合相であって、γ相中のC量が高いものを対象にしている。 Rolling performed in a conventional high temperature, a mixed phase of ferrite (alpha) + austenite (gamma), are directed to those C amount of gamma phase is high. α相は再結晶しにくいため圧延方向に伸長し、γ粒界から一部α相再結晶粒が析出する。 α phase is extended in the rolling direction for difficult to recrystallization, partial α phase recrystallized grains are precipitated from the γ grain boundaries. このような組織を有する圧延材を放冷すると、γがマルテンサイトに変態するとともにCr 236が析出し、その近傍には欠乏層ができる。 When cool the rolled material having such a structure, gamma is Cr 23 C 6 precipitates with transformed to martensite, the in the vicinity can depletion layer. それゆえ、熱処理を行なわなければならないわけである。 Therefore, it is not must be performed to a heat treatment. これに対し、本発明にしたがって低温で圧延を進めると、γ相が存在しないためα粒が成長し、圧延方向に伸長する。 In contrast, when advancing the rolling at a low temperature in accordance with the present invention, alpha particle because γ-phase is not present to grow and extend in the rolling direction. この圧延材を放冷すると、マルテンサイトの析出はないものの、Cr 236が析出し、その近傍に欠乏層ができることは同じである。 When cool the rolled material, although deposition is no martensite, Cr 23 C 6 are precipitated, it is the same that can depletion layer in the vicinity thereof. そこで徐冷すれば、ある程度高い温度に長時間置かれることにより、α粒は若干成長すると思われるが、前記のようにCrの拡散が起こってCr 236が消失し、かつ、加工硬化が解消して、軟らかい材料となる。 So if slow cooling, by being placed prolonged somewhat higher temperatures, but it seems α grains grow slightly, Cr 23 C 6 happening diffusion Cr as described above disappears and work hardening It has been eliminated, the soft material.

上記の圧延温度と徐冷の模様は、図3(従来法)および図4(本発明)に見るとおりである。 Pattern rolling temperature and slow cooling above is as seen in Figure 3 (conventional method) and 4 (present invention). 従来法(図3)は、たとえば1150℃というような高温から圧延が始まり、次第に温度が低下してCr 236ノーズを横ぎる。 Conventional method (FIG. 3) is, for example, hot rolling begins as of 1150 ° C., the horizontal Gill Cr 23 C 6 nose gradually lowered temperature. 冷却速度が、たとえば2〜3℃/秒といった通常の冷却であると、Cr欠乏層を形成する領域(斜線部分)に触れ、かつ、マルテンサイトの析出を見る。 The cooling rate is, for example, is a normal cooling such 2 to 3 ° C. / sec, touching the area (hatched portion) forming a Cr-deficient layer, and observing deposition of the martensite. Cr欠乏層の形成を避けるためには、0.1℃/秒以下の、非常に遅い冷却をしなければならない。 In order to avoid the formation of Cr-depleted layer is of 0.1 ° C. / sec or less, it must be very slow cooling. 遅い冷却を実施したとしても、マルテンサイトができているため、熱処理をしなければならない。 Even if carried out slow cooling, because they can martensite, must be heat-treated.

これに対し、本発明(図4)では、α単相の領域で圧延が進行し、マルテンサイトの析出もない。 In contrast, in the present invention (FIG. 4), the rolling proceeds in the region of the α single phase, there is no precipitation of martensite. Cr欠乏層の形成を避けるためには、やはり徐冷が必要であるが、前記したように0.3℃/秒以下の冷却速度で、通常は足りる。 In order to avoid the formation of Cr-depleted layer is again but slow cooling is necessary, at a cooling rate of 0.3 ° C. / sec or less as described above, usually sufficient. しかしこの場合も、できれば0.1℃/秒程度の遅い冷却をすることが望ましい。 But in this case, it is desirable to slow cooling of about 0.1 ° C. / sec if possible. 前述の機構にかんがみれば、徐冷に当たってある温度にある時間、たとえば後記する実施例の830℃×7分間とか9分間とか保持することが、Crの拡散による欠乏層の消滅や加工硬化の解消をもたらす上で有効である。 Given the foregoing mechanism, the time in the temperature that is hitting the slow cooling, for example, be held Toka 830 ° C. × 7 min Toka 9 minutes Examples described below, the elimination of disappearance and work hardening depletion layer due to the diffusion of Cr it is effective in providing.

フェライト系ステンレス鋼SUS430(C:含有量0.04%)を溶製し、表1に記した温度条件で線材圧延して、径13mmの線材コイルとした。 Ferritic stainless steel SUS430: smelted and (C content 0.04%) and rolled wire rod at the temperature conditions noted in Table 1, was wire coil diameter 13 mm.
表1 Table 1
抽 出 巻取時 Extraction of the winding
比較例 1100℃ 850℃ Comparative Example 1100 ℃ 850 ℃
実施例 900℃ 820℃ EXAMPLE 900 ° C. 820 ° C.
コイルの冷却に当たっては、下記の3種の条件を試みた: When the coil cooling, tried three of the following conditions:
(1)ループコンベア上でヘビーパックの状態で放冷した(冷却速度約0.1℃/秒) (1) was allowed to cool in a state of heavy pack on the loop conveyor (cooling rate of about 0.1 ° C. / sec)
(2)上記に加え、830℃の大気炉内に7分間置いた(3)上記に加え、830℃の大気炉内に9分間置いた (2) In addition to the above, in addition to 830 ° C. of at 7 minutes to the atmosphere furnace (3) above, it was placed 9 minutes in air oven at 830 ° C.

得られた線材について、引張り強さと絞りを測定して冷間加工性を評価するとともに、腐食減量を測定して耐食性を確認した。 The obtained wire, together with measuring the strength and stop pulling evaluating cold workability, to confirm the corrosion resistance by measuring the corrosion weight loss. 結果を表2に示す。 The results are shown in Table 2.
表2 Table 2
比較例 実施例 Comparative Example Example
冷却条件 (1) (2) (3) (1) (2) (3) Cooling conditions (1) (2) (3) (1) (2) (3)
引張り強さ(kg/cm 2 ) 71.0 61.5 61.0 55.5 45.1 44.4 Tensile strength (kg / cm 2) 71.0 61.5 61.0 55.5 45.1 44.4
絞り(%) 56.2 56.9 59.7 73.2 81.3 84.2 Iris (%) 56.2 56.9 59.7 73.2 81.3 84.2
腐食減量(g/m 3 /hr) 12.7 0.75 0.60 9.3 0.72 0.29 Corrosion weight loss (g / m 3 / hr) 12.7 0.75 0.60 9.3 0.72 0.29

上記の試験において、目標としたレベルは、引張り強さが55kg/cm 2以下、絞りが75%以上、腐食減量が1.0g/m 3 /hr以下である。 In the above test, the level with the goal, the tensile strength of 55 kg / cm 2 or less, the diaphragm 75% or more, the corrosion weight loss is less than 1.0g / m 3 / hr. 本発明の実施例は容易に目標を超えたが、比較例は圧延条件が満たされていないため、耐食性以外は不満足なものであった。 Examples of the present invention has been exceeded readily goals, because the comparative example unmet rolling conditions, except the corrosion resistance was unsatisfactory. 実施例においては、冷却の途中で加熱保持が効果的であることがわかる。 In the embodiment, it is understood that heating maintained during the cooling is effective.

上記した本発明の実施例で得たものと同じ材質の線材であって、径5.5mmのものを、径2.0mmまで伸線した。 A wire of the same material as those obtained in Example of the present invention described above, those of diameter 5.5 mm, was drawn to diameter 2.0 mm. その間における種々の冷間の加工率段階で、引張り強さを測定した。 In processing rate stage between various cold in the meantime, it was measured tensile strength. その結果を、従来法で(圧延後の熱処理を伴う)製造したものと比較して、図5に示す。 The results, in the conventional method (with heat treatment after rolling) compared to those produced, shown in Figure 5. 本発明の方法で製造した線材が、従来法によるものと同等の冷間加工性を有することが、このグラフから確認できる。 Wire material manufactured by the method of the present invention, to have cold workability equivalent to that by the conventional method, can be confirmed from the graph.

加熱炉からの抽出および圧延における材料温度の時間の経過に伴う変化を追って示した図。 It illustrates chasing changes over time of the material temperature in the extraction and rolling from the heating furnace. 白抜き丸のプロットは従来法、黒角のプロットは本発明。 Conventional methods plot of white circles, the plot of black angles present invention. Fe−17%Crの系において、炭素量と温度とにより決定される相をサーモカルクにより画いた状態図。 In the system of Fe-17% Cr, state diagram Egai by Samokaruku the phase determined by the carbon content and the temperature. 圧延材の温度変化をCr 236ノーズとの関連において示したグラフであって、従来の方法の場合。 The temperature change of the rolled material a graph showing the relation between the Cr 23 C 6 nose, in the conventional method. 図3と同様、圧延材の温度変化をCr 236ノーズとの関連において示したグラフであって、本発明の方法にしたがった場合。 Similar to FIG. 3, when the temperature change of the rolled material a graph showing the relation between the Cr 23 C 6 nose, in accordance with the method of the present invention. 本発明の方法で製造した線材の冷間加工性を示す図であって、種々の加工率における引張り強さを、従来法により製造した線材のそれと比較したグラフ。 A diagram showing the cold workability of the wire material manufactured by the method of the present invention, a graph of the tensile strength at various processing rates, and compared with that of the wire material manufactured by the conventional method.

Claims (2)

  1. ステンレス鋼の線材を製造する方法であって、C含有量0.10%以下のフェライト系ステンレス鋼を、700℃以上であってγ変態点以下の温度において線材圧延し、0.3℃/秒以下の冷却速度で徐冷することからなるステンレス鋼線材の製造方法。 A method of manufacturing a wire of stainless steel, the C content 0.10% of the ferritic stainless steel, and rolled wire at 700 ° C. or higher in an in γ transformation point temperature, 0.3 ° C. / sec method for producing a stainless steel wire made of gradual cooling in the following cooling rates.
  2. 圧延後の徐冷を、ループコンベア上にある圧延材に対し、ヒーターの熱を与えることにより0.1℃/秒以下の冷却速度で実施する請求項1のステンレス鋼線材の製造方法。 Slow cooling after rolling, to the rolling member in the loop conveyor, the production method of the stainless steel wire of claim 1 carried out in the following cooling rate 0.1 ° C. / sec by applying heat of the heater.
JP2004037819A 2004-02-16 2004-02-16 Stainless steel wire manufacturing method Pending JP2005226147A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2457911C1 (en) * 2011-02-10 2012-08-10 Открытое акционерное общество "Магнитогорский металлургический комбинат" Method of producing hot-rolled wire

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2457911C1 (en) * 2011-02-10 2012-08-10 Открытое акционерное общество "Магнитогорский металлургический комбинат" Method of producing hot-rolled wire

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