JPS625214B2 - - Google Patents
Info
- Publication number
- JPS625214B2 JPS625214B2 JP58185190A JP18519083A JPS625214B2 JP S625214 B2 JPS625214 B2 JP S625214B2 JP 58185190 A JP58185190 A JP 58185190A JP 18519083 A JP18519083 A JP 18519083A JP S625214 B2 JPS625214 B2 JP S625214B2
- Authority
- JP
- Japan
- Prior art keywords
- coil
- less
- gas
- hot
- rolled
- 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
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 34
- 239000010959 steel Substances 0.000 claims description 34
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 6
- 238000002844 melting Methods 0.000 claims description 5
- 230000008018 melting Effects 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 4
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 3
- 230000006698 induction Effects 0.000 claims description 3
- 230000001590 oxidative effect Effects 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 21
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 16
- 238000000034 method Methods 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 238000007664 blowing Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 238000005098 hot rolling Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 238000007789 sealing Methods 0.000 description 6
- 238000004804 winding Methods 0.000 description 6
- 238000001816 cooling Methods 0.000 description 5
- 238000011282 treatment Methods 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000005452 bending Methods 0.000 description 3
- 239000012141 concentrate Substances 0.000 description 3
- 238000009749 continuous casting Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005554 pickling Methods 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 208000023514 Barrett esophagus Diseases 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229920000298 Cellophane Polymers 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010411 cooking Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Description
（産業上の利用分野）
本発明はパイプ、ドラム、成型形鋼その他一般
加工用の熱延鋼板の製造方法に関する。
（従来技術）
連続鋳造鋳片を熱間圧延して製造した鋼板は、
二次スケールの密着性が悪いため、酸洗後ボンデ
処理等の表面処理を実施したのち成形加工を行な
いドラム、パイプ等の製品としその後表面被覆す
る方法が採用されていた。
（発明の目的）
本発明は酸洗やボンデ処理の必要がなく、加工
メーカーで直ちに成形加工し表面被覆を行うこと
が可能なスケール密着性の優れた熱延鋼板の製造
法を提供することにある。
（発明の構成・作用）
前述の如く、連続鋳造鋳片を素材として製造し
た熱延鋼板はスケール密着性が悪いため、種々の
表面処理加工を必要としていたが、経済性に不利
であるため、従来のような複雑な表面処理工程を
必要としないスケール密着性の優れた熱延鋼板の
開発研究を行つた結果本発明者等はより簡易な手
段により目的を達成できる方法の開発に成功し
た。
本発明の要旨は、C0.03〜0.25％，Si0.03％以
下、Mn0.20〜1.00％，P0.020％以下、S0.020％以
下、Al0.05％以下、Cu0.03％以下、Cr0.03％以下
であつて、さらに、残りがFeおよび不可避不純
物からなる低炭素鋼を溶製後、連続鋳造した鋳片
を直接熱間圧延するか、もしくは誘導加熱装置、
ガス加熱装置などによつて端部等の温度低下しや
すい部分を軽加熱した後熱間圧延し、550〜700℃
で捲取つたコイルをN2ガスあるいはアルゴンガ
スもしくはそれらの混合ガス雰囲気中で350℃に
達するまで冷却することを特徴とするスケール密
着性の優れた熱延鋼板の製造方法、であつて、以
下さらに詳細に説明する。
本発明における成分の限定理由は、本発明の目
的とする加工用途に適応した鋼板を提供するため
であり、C0.03〜0.25％とする理由は、本発明に
かかる熱延鋼板の用途、即ちパイプ、ドラム、成
型型鋼、自動車フレーム、料理用鍋などに適した
特性を与えるためで、これらには主に低炭素〜中
炭素鋼が適している。Ｃは成品では大部分Fe3C
（セメンタイト）となり、スケール密着性を悪化
させるので、出来るだけ低目が望ましいが、自動
車のフレーム、建材、パイプ等では強度が必要
で、両者を満足させるには0.25％が上限となり、
またドラム材等に適当なＣ成分は0.03％が限度と
なり、これが本発明におけるＣ成分の下限を0.03
％とする理由である。
次にSiを0.03％以下とする理由は、これ以上で
は本発明の目的とする鋼板の特性を損ねるためで
ある。Siは加熱中または熱延中および捲取後地鉄
表面に濃化し、地鉄とスケール密着性を悪くす
る。特に通常加熱すると悪くなるので、本発明で
は連続鋳片を直接圧延し、かつSi含有量は少ない
ほうが良く、0.03％以下がよい。
またMnを0.20〜1.00％とする理由は、Mnは二
次スケールの密着性に望ましい元素であるが、
0.20％未満では本発明の目的とする鋼板の強度上
問題があり、また1.00％超では経済性を失なうた
めである。
次にＰ，Ｓを0.020％以下とする理由は、Ｐ，
Ｓともに二次スケールと地鉄界面に濃化し、スケ
ール密着性を悪くするためで、0.020％が限界で
ある。目的のためにはＰ，Ｓともに含有量がたと
えば0.010％以下が望ましいが、脱Ｐ，脱Ｓとも
に処理コストが嵩むので経済上の許容範囲を考慮
して、含有量は0.030％以下で適宜決定すべきで
ある。
また、Alを0.05％以下とする理由は、目的とす
る鋼板製造のためAl脱酸した場合、Alの含有は
不可避的であり、目的に対し影響の限界を調査し
た結果0.05％まで好結果が認められたためであ
る。而して0.05％超では経済的に問題が生ずる。
そこで本発明ではAlの含有量を0.05％以下とし
た。
同様にCuを0.03％以下、Crを0.03％以下とす
る理由はCu，Crともに加熱および熱延中にスケ
ールと地鉄界面に濃化し二次スケール密着性を悪
くするためでCu，Crともに本発明では0.03％が
限界であり、Cuの下限は0.003％，Crは0.005％
である。
本発明は再加熱の代りに直接圧延法を採用して
いるため再加熱時の高温度、長時間の加熱がな
く、そのため地鉄表面への不純物元素の濃化が少
なくなり、鋼成分中のSi，Ｐ，Ｓ，Cu，Crなど
を再加熱材よりやや高目にとつても熱延鋼板のス
ケール密着性が良好になる利点がある。
本発明における前述の成分の鋼は、周知の溶銑
の脱Ｐ，脱Ｓや脱Siなどの予備処理を必要に応じ
て適宜実施したのち、上あるいは底吹きもしくは
上底吹きの転炉によつて溶製し、次にRH処理等
の事前処理をするか、もしくはしないで連続鋳造
装置によつて鋳片、たとえばスラブあるいはブル
ームに鋳造する。
ついで該連続鋳造装置によつて得られた高温鋳
片をそのまま直接熱間圧延するかあるいは軽加
熱、即ち誘導加熱装置、ガス加熱装置などによつ
て端部等の温度低下しやすい部分を加熱しさら
に、粗および仕上圧延装置により熱間圧延して所
望の板厚とし、ついで550〜700℃の高温巻取りを
行う。本発明では直接圧延するため、スケールと
地鉄界面に濃縮する元素例えばSi，Ｐ，Ｓ，
Cu，Crなどが低くなり、二次スケール密着性を
向上する。
この高温巻取を550〜700℃に限定する理由は次
の通りである。
一般に酸化鉄は570℃以上で、主にFeO相であ
るが、570℃以下で変態し、Fe3O4相とαFeに変
態する。しかし急冷すると変態が完全に進行せず
密着性のやや悪いFeO相を含む酸化鉄になる。徐
冷すると密着性のよいFe3O4相（αFeを含む）に
完全変態するので、変態温度直下の550℃以上で
熱延鋼板を捲取るとコイルの保有熱により徐冷さ
れFe3O4に変態し好ましい結果が得られる。これ
が下限温度を550℃とする理由である。即ち550℃
以下では酸化鉄中にFeO相が増加し好ましくな
い。次に700℃超で捲取るとスケール厚さが厚く
なり、スケール密着性が悪くなるため、捲取温度
は700℃が上限となる。
次に該高温巻取コイルを第１図に示すような実
施例装置に装入しコイル平均温度が350℃に達す
るまで冷却する。非酸化性雰囲気での冷却終了温
度を350℃と限定した理由は、550〜700℃で巻き
取られたコイル表面に酸化鉄のFeOが変態温度
（約570℃）以下でFe3O4に変態した後、高い温度
で空気中にさらされるとスケール密着性の悪い
Fe2O3になるので、出来るだけ低い温度、即ち
350℃位まで非酸化性雰囲気中で冷却すると
Fe3O4の含有分が多い二次スケールを有するもの
となり、二次スケール密着性の優れた熱延鋼板と
なる。第１図において、コイル１は水シール装置
３を有する作業床２に設けられた支承台４に載置
され、ついで密閉カバー８によつて気密状態に置
かれる。而して水シールの代りにサンドシールや
両者を組合せたものでもよい。
密閉カバー８には側壁にN2ガス，Arガス等の
気体送給管５ａ〜５ｆに接続された吹込ノズル６
ａ〜６ｆが固着されている。７ａ〜７ｆは開閉バ
ルブで、９ａはN2用、９ｂはAr用の排気管であ
る。
さて、熱間圧延され550〜700℃で巻取られたコ
イルはテーブルロール，クレーン等の適宜な搬送
手段で前記支承台４上に載置され密閉カバー８が
かぶせられる。密閉カバーの端縁８ａは水中に浸
漬し、気密性を保持する。
ついで図示していない供給源から吹込ノズル６
ａ〜６ｆを介してたとえばN2ガスを吹込むと排
気管９ａから空気が排出され、密閉カバー８内が
N2ガスで充満された後、バルプ１０ａを閉じ
る。
冷却の必要によつてはバルブ１０ａを常開とし
排気管９ａから常に排気させるようにしておいて
も差しつかえない。
なお１１ａ〜１１ｅは気体送給管の１部をなす
伸縮自在管であつて、密閉カバー８を図示してい
ないクレーンによつて吊上，吊下げする場合に伸
縮して移動を容易ならしめ作業性を高める目的に
用いる。この伸縮自在管１１ａ〜１１ｅにかえ
て、作業性のよいガス管用の着脱自在な弁継手を
用いても良い。
さてこのように不活性雰囲気においてコイル冷
却を行うと、通常の空冷ではコイル表面特にトツ
プ、ボトムおよび両縁部など酸化してFe2O3の含
有分が多い二次スケールの生成しやすい部位が
Fe3O4の含有分の多い二次スケールを有するもの
となり、二次スケール密着性の優れた熱延鋼板と
なる。本発明におけるスケール密着性は、曲げ試
験片の中央部外面にセロテープを貼付後試験片厚
みと同じ曲率半径で90゜曲げた後セロテープをは
がし判定した。スケール密着性が良好なものを〇
印、一部剥離し、やや不良のものを△印、大部分
剥離し、不良のものを×印とした。
このような測定結果から本発明において650℃
の場合、両端部はもとより全長、全幅にわたりス
ケール密着性は極めて良いことが判る。
第２図は本発明の方法を実施するための異なつ
た装置の概略説明図であつて、作業床２に穿設さ
れたピツト１７を囲繞して設けられた支持台１２
の上面に、フレキシブルシール台１３を介して密
閉カバー８０が着脱自在に配置されており、コイ
ル１は図示していないクレーン等の運搬装置によ
り支持台１２に架設された有孔支持板１８上に載
置されるが、当然のことながらその前に図示して
いない吊上クレーンによつて密閉カバー８０を吊
上げておきコイル１の載置が済んだのち吊下げ
る。
６ｇ，６ｈは密閉カバー８０と前記作業床２の
ピツト１７に設けられた吹込ノズルで多孔の吹込
口１４ａ，１４ｂ、マニホールド１４ｃ，１４ｄ
を備え不活性ガス供給管１６ａ，１６ｂに接続さ
れている。１５は開閉バルブを示す。
９０ａ，９０ｂは排気管であり、上下の方向か
ら吹込ノズル６ｇ，６ｈを介し図示していない
N2，Ar等の不活性ガス供給装置から所定量のガ
スを供給するとコイルの下側では有孔支持板１８
に設けられた貫通孔（図示していない）を通り、
上側では直接にコイル１の端面にガスが吹きつけ
られる。ついで密閉カバー８０の内側は速やかに
不活性ガスで充満されコイル１の両端面および縁
部を含めその全表面に密着性の優れたスケールが
生成される。
前記装置例の有孔支持板１８よるコイル１の支
持にかえて支持台１２に横梁を適宜数配設し、コ
イル１を支持するとガスが横梁間の空間を通りコ
イル１の下端面に達するので、同様に端縁の酸化
防止を効果的に達成できる。
このように目的の範囲を逸脱しない範囲におい
て、装置の設計を変えても差しつかえない。
実施例 １
第１表に示す成分組成の低炭素鋼を溶製後、連
続鋳造し直接圧延により熱延仕上温度840℃、巻
取温度550℃，650℃で巻取後、第１図の装置に装
入し、N2ガスを800／分の流量で３分間吹込み
その後、流量を100／分としコイル表面温度が
350℃に達するまで吹込んだ。
比較材として同一成分の鋼を575℃，650℃で巻
取後空冷（ブロワーよる強制冷却）した。その結
果空冷材の幅方向端部のスケール密着性はテーピ
ング曲げ試験で悪く、それに対し本発明の方法に
よるコイルについては全長，全幅において良好で
あつた。その比較を第３図に示す。
第３図は、横軸にコイル中央部巾方向寸法をと
り、縦軸にスケール密着性をとつて、巻取温度
650℃，550℃におけるN2シールした本発明の場
合と通常の空冷のコイルついて比較したもので、
本発明では特に端部のスケール密着性は飛躍的に
向上していることが判る。650℃捲取後空冷した
コイルの巾方向端部はFe2O3の多いスケールで密
着性がとくに悪い。
(Industrial Application Field) The present invention relates to a method for producing hot rolled steel sheets for pipes, drums, shaped steel and other general processing. (Prior art) Steel plates manufactured by hot rolling continuously cast slabs are
Because of the poor adhesion of secondary scale, a method has been adopted in which surface treatment such as bonding treatment is carried out after pickling, followed by molding to produce products such as drums and pipes, followed by surface coating. (Objective of the invention) The present invention provides a method for producing hot rolled steel sheets with excellent scale adhesion, which does not require pickling or bonding treatment and can be immediately formed and surface coated at a processing manufacturer. be. (Structure and operation of the invention) As mentioned above, hot-rolled steel sheets manufactured from continuously cast slabs have poor scale adhesion and require various surface treatments, but these are disadvantageous economically. As a result of conducting research and development to develop a hot rolled steel sheet with excellent scale adhesion that does not require the conventional complicated surface treatment process, the present inventors succeeded in developing a method that achieves the objective by simpler means. The gist of the present invention is C0.03-0.25%, Si0.03% or less, Mn0.20-1.00%, P0.020% or less, S0.020% or less, Al0.05% or less, Cu0.03% or less, After melting a low carbon steel with a Cr content of 0.03% or less and the remainder consisting of Fe and unavoidable impurities, the continuously cast slab is directly hot rolled or an induction heating device is used.
After lightly heating the edges and other areas where the temperature tends to drop using a gas heating device, hot rolling is performed to 550 to 700℃.
A method for producing a hot-rolled steel sheet with excellent scale adhesion, characterized by cooling a coil wound with N2 gas, argon gas, or a mixture thereof until it reaches 350°C, the method comprising: This will be explained in more detail. The reason for limiting the components in the present invention is to provide a steel sheet that is suitable for the processing applications targeted by the present invention, and the reason for setting C0.03 to 0.25% is to provide a steel sheet that is suitable for the processing applications targeted by the present invention. This is to give properties suitable for pipes, drums, molded steel, automobile frames, cooking pots, etc., and low to medium carbon steels are mainly suitable for these. C is mostly Fe 3 C in finished products
(cementite) and worsens scale adhesion, so it is desirable to have it as low as possible, but automobile frames, building materials, pipes, etc. require strength, and to satisfy both, 0.25% is the upper limit.
In addition, the limit of the C component suitable for drum materials, etc. is 0.03%, which is the lower limit of the C component in the present invention of 0.03%.
This is the reason why it is set as %. Next, the reason why Si is set to 0.03% or less is that if it exceeds this, the properties of the steel sheet that are the object of the present invention will be impaired. Si concentrates on the surface of the steel base during heating or hot rolling and after rolling up, impairing the adhesion of the scale to the base steel. In particular, heating usually deteriorates the quality, so in the present invention it is better to directly roll the continuous slab and have a lower Si content, preferably 0.03% or less. Also, the reason why Mn is set at 0.20 to 1.00% is that Mn is a desirable element for adhesion of secondary scales, but
If it is less than 0.20%, there will be a problem in terms of the strength of the steel sheet, which is the object of the present invention, and if it exceeds 1.00%, it will be uneconomical. Next, the reason for setting P and S to 0.020% or less is that P,
This is because both S concentrates at the interface between the secondary scale and the steel base, impairing scale adhesion, and the limit is 0.020%. For this purpose, it is desirable for the content of both P and S to be 0.010% or less, but since processing costs for both P and S removal increase, the content is determined as appropriate at 0.030% or less, taking into account the economic tolerance range. Should. In addition, the reason why Al is set at 0.05% or less is that when deoxidizing Al for the purpose of manufacturing steel sheets, the inclusion of Al is unavoidable, and after investigating the limit of the effect on the purpose, good results were found up to 0.05%. This is because it was recognized. However, if it exceeds 0.05%, an economic problem will occur.
Therefore, in the present invention, the Al content is set to 0.05% or less. Similarly, the reason for setting Cu to 0.03% or less and Cr to 0.03% or less is that both Cu and Cr concentrate at the interface between the scale and the steel base during heating and hot rolling, worsening secondary scale adhesion. In the invention, the limit is 0.03%, the lower limit for Cu is 0.003%, and for Cr is 0.005%.
It is. Since the present invention uses a direct rolling method instead of reheating, there is no need for high temperatures or long heating times during reheating, which reduces the concentration of impurity elements on the surface of the steel base, and reduces the concentration of impurity elements in the steel components. Even if the content of Si, P, S, Cu, Cr, etc. is slightly higher than that of the reheated material, there is an advantage in that the scale adhesion of the hot rolled steel sheet is improved. In the present invention, the steel having the above-mentioned components is prepared by carrying out the well-known preliminary treatment of hot metal, such as deP, S, and Si, as necessary, and then using a top-, bottom-blowing, or top-bottom blowing converter. It is melted and then cast into a billet, e.g. slab or bloom, in a continuous casting machine with or without pre-treatment such as RH treatment. Next, the high-temperature slab obtained by the continuous casting device is directly hot-rolled as it is, or it is lightly heated, that is, by heating the parts where the temperature tends to drop, such as the ends, using an induction heating device, a gas heating device, etc. Further, the sheet is hot-rolled to a desired thickness using rough and finish rolling equipment, and then coiled at a high temperature of 550 to 700°C. In the present invention, since direct rolling is performed, elements such as Si, P, S,
Cu, Cr, etc. are reduced, improving secondary scale adhesion. The reason why this high temperature winding is limited to 550 to 700°C is as follows. In general, iron oxide is mainly in the FeO phase at temperatures above 570°C, but at temperatures below 570°C it transforms into the Fe 3 O 4 phase and αFe. However, if it is rapidly cooled, the transformation does not proceed completely and it becomes iron oxide containing a FeO phase with slightly poor adhesion. Slow cooling completely transforms into Fe 3 O 4 phase (including αFe) with good adhesion, so when a hot rolled steel sheet is rolled up at 550°C or higher, just below the transformation temperature, Fe 3 O 4 is slowly cooled by the heat retained in the coil. This results in favorable results. This is the reason why the lower limit temperature is set at 550°C. i.e. 550℃
In the following, FeO phase increases in iron oxide, which is not preferable. Next, the upper limit of the winding temperature is 700°C because the scale becomes thicker and the scale adhesion deteriorates if it is rolled at a temperature higher than 700°C. Next, the high-temperature wound coil is placed in the embodiment shown in FIG. 1 and cooled until the average coil temperature reaches 350°C. The reason why we limited the cooling end temperature in a non-oxidizing atmosphere to 350℃ is that iron oxide FeO on the surface of the coil wound at 550 to 700℃ transforms to Fe 3 O 4 below the transformation temperature (approximately 570℃). After that, if exposed to air at high temperature, scale adhesion will be poor.
Since it becomes Fe 2 O 3 , the temperature is as low as possible, i.e.
When cooled to about 350℃ in a non-oxidizing atmosphere,
The hot-rolled steel sheet has secondary scale with a high content of Fe 3 O 4 and has excellent secondary scale adhesion. In FIG. 1, the coil 1 is placed on a support 4 provided on a work floor 2 with a water sealing device 3 and then placed in an airtight state by means of a sealing cover 8. Instead of the water seal, a sand seal or a combination of both may be used. The airtight cover 8 has a blowing nozzle 6 connected to the gas supply pipes 5a to 5f for N 2 gas, Ar gas, etc. on the side wall.
a to 6f are fixed. 7a to 7f are on-off valves, 9a is an exhaust pipe for N2 , and 9b is an exhaust pipe for Ar. Now, the coil that has been hot-rolled and wound at 550 to 700 DEG C. is placed on the support base 4 using an appropriate conveyance means such as a table roll or a crane, and covered with a sealing cover 8. The edge 8a of the sealing cover is immersed in water to maintain airtightness. The blowing nozzle 6 is then supplied from a supply source (not shown).
If, for example, N 2 gas is blown through a to 6f, air will be exhausted from the exhaust pipe 9a, and the inside of the airtight cover 8 will be
After being filled with N 2 gas, valve 10a is closed. Depending on the need for cooling, the valve 10a may be kept open to constantly exhaust air from the exhaust pipe 9a. Note that 11a to 11e are expandable tubes that form part of the gas supply tube, and are expanded and contracted to facilitate movement when the airtight cover 8 is lifted or suspended by a crane (not shown). Used for the purpose of enhancing sex. Instead of the telescopic tubes 11a to 11e, detachable valve joints for gas pipes with good workability may be used. Now, when the coil is cooled in an inert atmosphere as described above, the parts of the coil surface that are easily oxidized and generate secondary scale containing a large amount of Fe 2 O 3 , especially the top, bottom and both edges, are susceptible to oxidation during normal air cooling.
The hot-rolled steel sheet has secondary scale with a high content of Fe 3 O 4 and has excellent secondary scale adhesion. Scale adhesion in the present invention was determined by attaching cellophane tape to the outer surface of the central part of a bending test piece, bending it by 90 degrees with the same radius of curvature as the thickness of the test piece, and then peeling off the cello tape. Those with good scale adhesion were marked with ◯, partially peeled off, those with slightly poor scale adhesion were marked with △, and most of them were peeled off, and those with poor scale were marked with ×. Based on these measurement results, in the present invention, 650℃
In the case of , it can be seen that the scale adhesion is extremely good not only at both ends but also over the entire length and width. FIG. 2 is a schematic explanatory diagram of different apparatuses for carrying out the method of the present invention, in which a support stand 12 is provided surrounding a pit 17 drilled in the work floor 2.
A sealing cover 80 is removably arranged on the upper surface via a flexible seal stand 13, and the coil 1 is mounted on a perforated support plate 18 which is constructed on the support stand 12 by a transportation device such as a crane (not shown). However, before that, the sealing cover 80 is lifted up by a lifting crane (not shown), and after the coil 1 has been placed, it is hung down. 6g and 6h are blowing nozzles provided in the airtight cover 80 and the pit 17 of the work floor 2, including porous blowing ports 14a and 14b, and manifolds 14c and 14d.
and is connected to inert gas supply pipes 16a and 16b. 15 indicates an on-off valve. 90a and 90b are exhaust pipes, which are not shown through blow nozzles 6g and 6h from above and below.
When a predetermined amount of gas is supplied from an inert gas supply device such as N 2 or Ar, a perforated support plate 18 is formed on the lower side of the coil.
through a through hole (not shown) provided in the
On the upper side, gas is blown directly onto the end face of the coil 1. Then, the inside of the airtight cover 80 is quickly filled with inert gas, and a highly adhesive scale is formed on the entire surface of the coil 1, including both end faces and edges. Instead of supporting the coil 1 by the perforated support plate 18 in the above device example, if an appropriate number of cross beams are arranged on the support base 12 to support the coil 1, gas will pass through the space between the cross beams and reach the lower end surface of the coil 1. Similarly, edge oxidation prevention can be effectively achieved. In this way, it is permissible to change the design of the device as long as it does not deviate from the intended scope. Example 1 After melting low carbon steel having the composition shown in Table 1, it was continuously cast and directly rolled at a hot rolling finishing temperature of 840°C and a coiling temperature of 550°C and 650°C. N2 gas was blown into the coil at a flow rate of 800/min for 3 minutes, then the flow rate was increased to 100/min, and the coil surface temperature was
Blowing was continued until the temperature reached 350°C. For comparison, steel with the same composition was rolled up at 575°C and 650°C and then air cooled (forced cooling using a blower). As a result, the scale adhesion at the widthwise ends of the air-cooled material was poor in the taping bending test, whereas the coil produced by the method of the present invention was good over the entire length and width. A comparison is shown in FIG. In Figure 3, the width direction of the central part of the coil is plotted on the horizontal axis, the scale adhesion is plotted on the vertical axis, and the winding temperature is plotted.
This is a comparison between the case of the present invention sealed with N2 at 650℃ and 550℃, and the case of a normal air-cooled coil.
It can be seen that in the present invention, scale adhesion, especially at the edges, is dramatically improved. The ends in the width direction of the coil, which were air-cooled after being wound at 650°C, had a scale containing a lot of Fe 2 O 3 and had particularly poor adhesion.
【表】
実施例 ２
第２表に示す組成の鋼を溶製後、連続鋳造し直
接圧延により熱延仕上温度820℃、巻取温度600℃
で巻取り後、第１図に示す装置に装入し左右の供
給管からN2ガスを１m3／分の流量で２分間吹込
み、その後0.1m3／分の流量でコイル巾方向端部
の表面温度が350℃に達するまで吹込んだ。N2ガ
スの吹込量は総計約35m3であつた。
比較材としては連続鋳造して得た熱鋼片を1270
℃で加熱して得られたコイルをN2ガス中で冷却
し、350℃以下としたものを製造し、そのスケー
ル密着性を比較した。
本発明の方法によつて製造したコイルはすべて
スケール密着性が良く、比較材は劣つている。そ
の比較を第４図に示す。[Table] Example 2 After melting steel with the composition shown in Table 2, it was continuously cast and directly rolled to a hot-rolled finish temperature of 820°C and a coiling temperature of 600°C.
After winding up the coil, it is loaded into the device shown in Figure 1, and N 2 gas is blown into the left and right supply pipes at a flow rate of 1 m 3 / min for 2 minutes. Blowing was continued until the surface temperature reached 350℃. The total amount of N 2 gas blown was about 35 m 3 . As a comparative material, hot steel slabs obtained by continuous casting were used as 1270
A coil obtained by heating at ℃ was cooled in N 2 gas to a temperature of 350℃ or less, and the scale adhesion was compared. All of the coils manufactured by the method of the present invention had good scale adhesion, whereas the comparative materials were inferior. The comparison is shown in FIG.
【表】
第４図は、同様にコイル中央部巾方向寸法をと
り、縦軸にスケール密着性をとつて、巻取温度
600℃におけるN2シールした本発明の場合と通常
の再加熱したコイルについて比較したもので、本
発明では平均してスケール密着性は向上する。こ
れに対し再加熱のコイルは特に端部のスケール密
着性がやや劣つており地鉄とスケール界面での
Ｃ，Siの濃化が直接圧延材に比べ高い。
実施例 ３
第３表に示す組成の鋼を溶製後、連続鋳造し直
接圧延により熱延仕上温度840℃、巻取温度650℃
で巻取り後、第１図に示す装置に装入し左右の供
給管からN2ガスを0.8m3／分の流量で２分間吹込
み、その後0.1m3／分の流量でコイル巾方向端部
の表面温度が350℃に達するまで吹込んだ。N2ガ
スの吹込量は総計で約33m3であつた。
本発明の成分で製造したコイルは第５図に示す
様にスケール密着性が良く、成分の高目の比較材
は本発明材に比べSi，Ｐ，Ｓ，Cr，Cuなどが地
鉄／スケール界面で高く、スケール密着性が劣つ
ている。[Table] Figure 4 similarly shows the width direction dimension of the central part of the coil, scale adhesion on the vertical axis, and the winding temperature.
This is a comparison between the case of the present invention sealed with N 2 at 600°C and the conventional reheated coil, and the scale adhesion is improved on average in the present invention. On the other hand, the scale adhesion of reheated coils, especially at the ends, is somewhat poor, and the concentration of C and Si at the interface between the steel base and scale is higher than that of directly rolled materials. Example 3 After melting steel with the composition shown in Table 3, it was continuously cast and directly rolled to a hot rolling finish temperature of 840°C and a coiling temperature of 650°C.
After winding the coil, it is loaded into the device shown in Figure 1, and N 2 gas is blown into the left and right supply pipes at a flow rate of 0.8 m 3 / min for 2 minutes. Blowing was continued until the surface temperature of the part reached 350℃. The total amount of N 2 gas blown was approximately 33 m 3 . As shown in Figure 5, the coil manufactured with the components of the present invention has good scale adhesion, and the comparison material with higher components has less Si, P, S, Cr, Cu, etc. on the base metal/scale than the present invention material. It is high at the interface and has poor scale adhesion.
【表】
（発明の効果）
前述の通り、本発明の方法により製造したスケ
ール密着性の優れた熱延鋼板は、酸洗やボンデ処
理する必要がなくパイプ、ドラム等の製造に用い
たり、さらにフオーミング加工による溝型鋼や山
形鋼などの製造を行つた後、必要に応じて塗装す
ることが可能であり、極めて経済性に富む。本発
明は、かかる熱延鋼板を経済的に製造する手段を
提供するもので、実用効果の高い方法である。[Table] (Effects of the invention) As mentioned above, the hot-rolled steel sheet with excellent scale adhesion produced by the method of the present invention does not require pickling or bonding treatment, and can be used for manufacturing pipes, drums, etc. After manufacturing channel steel, angle steel, etc. by forming processing, it is possible to paint as necessary, making it extremely economical. The present invention provides a means for economically producing such hot rolled steel sheets, and is a method with high practical effects.
第１図は本発明の方法を実施するための実施例
装置の概略説明図、第２図は本発明の方法を実施
するための異なつた装置の概略説明図、第３図、
第４図、第５図は本発明に係るコイルと比較材コ
イルとのスケール密着性を比較したグラフであ
る。
１…コイル、２…作業床、３…水シール装置、
４…支承台、５ａ〜５ｆ…気体送給管、６ａ〜６
ｆ…吹込ノズル、７ａ〜７ｆ…開閉バルブ、８…
密閉カバー、９…排気管、１０…バルブ、１１ａ
〜１１ｅ…伸縮自在管、１２…支持台、１３…フ
レキシブルシール台、１４ａ，１４ｂ…吹込口、
１４ｃ，１４ｄ…マニホールド、１５…開閉バル
ブ、１６ａ，１６ｂ…不活性ガス供給管、１７…
ピツト、１８…有孔支持板、９０ａ，９０ｂ…排
気管。
FIG. 1 is a schematic explanatory diagram of an embodiment apparatus for implementing the method of the present invention, FIG. 2 is a schematic explanatory diagram of different apparatuses for implementing the method of the present invention, and FIG.
FIGS. 4 and 5 are graphs comparing scale adhesion between the coil according to the present invention and a comparison material coil. 1...Coil, 2...Working floor, 3...Water seal device,
4...Support stand, 5a-5f...Gas feed pipe, 6a-6
f...Blowing nozzle, 7a-7f...Opening/closing valve, 8...
Airtight cover, 9...exhaust pipe, 10...valve, 11a
~11e... Telescopic tube, 12... Support stand, 13... Flexible seal stand, 14a, 14b... Inlet,
14c, 14d...manifold, 15...open/close valve, 16a, 16b...inert gas supply pipe, 17...
Pit, 18... Perforated support plate, 90a, 90b... Exhaust pipe.
Claims (1)
1.00％、P0.020％以下、S0.020％以下、Al0.05％
以下、Cu0.03％以下、Cr0.03％以下であつて、
残りがFeおよび不可避不純物からなる低炭素鋼
を溶製後、連続鋳造した鋳片を直接熱間圧延する
か、もしくは誘導加熱装置、ガス加熱装置などに
よつて端部等の温度低下しやすい部分を軽加熱し
た後熱間圧延し、550〜700℃で巻き取つたコイル
をN2ガスあるいはArガスもしくはそれらの混合
ガスからなる非酸化性雰囲気中で350℃に達する
まで冷却することを特徴とするスケール密着性の
優れた熱延鋼板の製造方法。1 C0.03~0.25%, Si0.03% or less, Mn0.20~
1.00%, P0.020% or less, S0.020% or less, Al0.05%
Below, Cu is 0.03% or less, Cr is 0.03% or less,
After melting low-carbon steel, the remainder of which is Fe and unavoidable impurities, the continuously cast slab is directly hot-rolled, or parts where the temperature tends to drop, such as the edges, are heated using an induction heating device, gas heating device, etc. After being lightly heated, the coil is hot-rolled at 550 to 700℃ and then cooled in a non-oxidizing atmosphere consisting of N2 gas, Ar gas, or a mixture thereof until it reaches 350℃. A method for producing hot-rolled steel sheets with excellent scale adhesion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18519083A JPS6077922A (en) | 1983-10-05 | 1983-10-05 | Production of hot-rolled steel plate having high adhesion to scale |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18519083A JPS6077922A (en) | 1983-10-05 | 1983-10-05 | Production of hot-rolled steel plate having high adhesion to scale |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6077922A JPS6077922A (en) | 1985-05-02 |
| JPS625214B2 true JPS625214B2 (en) | 1987-02-03 |
Family
ID=16166426
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18519083A Granted JPS6077922A (en) | 1983-10-05 | 1983-10-05 | Production of hot-rolled steel plate having high adhesion to scale |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6077922A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01159348A (en) * | 1987-12-16 | 1989-06-22 | Kawasaki Steel Corp | H-shape steel having tight scale and its production |
| JP5343035B2 (en) * | 2010-04-30 | 2013-11-13 | 株式会社神戸製鋼所 | High Si content steel sheet with excellent surface properties and method for producing the same |
| JP5949167B2 (en) * | 2012-05-31 | 2016-07-06 | Ｊｆｅスチール株式会社 | Manufacturing method of steel sheet excellent in laser cutting property and steel sheet excellent in laser cutting property |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54109022A (en) * | 1978-02-14 | 1979-08-27 | Sumitomo Metal Ind Ltd | Manufacture of low strength hot rolled mild steel sheet |
| JPS5681632A (en) * | 1979-12-07 | 1981-07-03 | Sumitomo Metal Ind Ltd | Manufacture of hot rolled steel hoop having excellent scale adhesion |
| JPS6024320A (en) * | 1983-07-19 | 1985-02-07 | Nippon Steel Corp | Production of hot rolled steel sheet having excellent scale adhesion |
-
1983
- 1983-10-05 JP JP18519083A patent/JPS6077922A/en active Granted
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54109022A (en) * | 1978-02-14 | 1979-08-27 | Sumitomo Metal Ind Ltd | Manufacture of low strength hot rolled mild steel sheet |
| JPS5681632A (en) * | 1979-12-07 | 1981-07-03 | Sumitomo Metal Ind Ltd | Manufacture of hot rolled steel hoop having excellent scale adhesion |
| JPS6024320A (en) * | 1983-07-19 | 1985-02-07 | Nippon Steel Corp | Production of hot rolled steel sheet having excellent scale adhesion |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6077922A (en) | 1985-05-02 |
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