JPS625213B2 - - Google Patents
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- Publication number
- JPS625213B2 JPS625213B2 JP58130356A JP13035683A JPS625213B2 JP S625213 B2 JPS625213 B2 JP S625213B2 JP 58130356 A JP58130356 A JP 58130356A JP 13035683 A JP13035683 A JP 13035683A JP S625213 B2 JPS625213 B2 JP S625213B2
- Authority
- JP
- Japan
- Prior art keywords
- hot
- less
- gas
- scale
- temperature
- 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
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- 229910000831 Steel Inorganic materials 0.000 claims description 35
- 239000010959 steel Substances 0.000 claims description 35
- 238000010438 heat treatment Methods 0.000 claims description 15
- 238000001816 cooling Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 230000001590 oxidative effect Effects 0.000 claims description 5
- 238000009749 continuous casting Methods 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims description 2
- 230000008018 melting Effects 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 17
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 12
- 238000000034 method Methods 0.000 description 10
- 238000005098 hot rolling Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 229910052717 sulfur Inorganic materials 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 238000007664 blowing Methods 0.000 description 6
- 229910052698 phosphorus Inorganic materials 0.000 description 6
- 238000004804 winding Methods 0.000 description 6
- 238000005452 bending Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 239000004576 sand Substances 0.000 description 5
- 229910052804 chromium Inorganic materials 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000012141 concentrate Substances 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- 238000005554 pickling Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 229910000954 Medium-carbon steel Inorganic materials 0.000 description 2
- 229910052785 arsenic Inorganic materials 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 229910018125 Al-Si Inorganic materials 0.000 description 1
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910018520 Al—Si Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920000298 Cellophane Polymers 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 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
- 238000010411 cooking Methods 0.000 description 1
- -1 dephosphorization Chemical compound 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
- 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後工程でスケー
ルの粉塵が発生し環境上問題になつたり、特に密
着性の悪い端部が使用不可になつたり、或いは酸
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）
本発明は後工程で粉塵が発生せず、コイル全巾
加工用に使用可能な或い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
被覆も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。
本発明の要旨とするところはC0.03〜0.25％、
Si0.05％以下、Mn0.20〜1.00％、P0.020％以下、
S0.020％以下、Cu0.05％以下、Cr0.05％以下、
Al0.08％以下、で残りがFeおよび不可避不純物
からなる鋼を溶製後、連続鋳造して得た熱鋼片を
直ちに加熱炉に装入するかもしくは一旦冷片とし
たのち加熱炉に装入し950〜1200℃で抽出して熱
間圧延を行い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にある。
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
である。
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0.05％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
あり、SiはAlキルド、Al―Siキルド鋼では脱酸の
ため使用されるので不可避的に含有される。本発
明ではSi含有量は少ないほうが良く目的を損なわ
ない範囲は0.05％以下である。
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、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0.020
％以下で適宜決定すべきである。
また、Alを0.08％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0.08％まで好結果が認められたためである。
而して0.08％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0.08％以下とした。
同様にCuを0.05％以下、Crを0.05％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0.05％が限界であ
る。
また、Sn，As，NiもCu，Crと同様に二次スケ
ール密着性を悪化させる元素であり含有されるこ
とは好ましくないが不可避不純物としての混入程
度であれば許容できる。
本発明における前述の成分の鋼は、周知の溶鉄
の脱Ｐ，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熱鋼板状態で加熱炉に
装入するか、一旦冷片状態としたものを再加熱し
て熱間圧延を行うが、前記加熱炉における加熱温
度（抽出温度）は950〜1200℃の温度範囲とす
る。このような950〜1200℃と云う低温加熱を行
う理由は、1200℃超で加熱するとSi，Ｐ，Ｓ，
Cu，Cr，SnおよびAsなどが鋼片とスケール界面
或いは鋼片表面に濃化し、熱延鋼板の表面でも濃
化するため二次スケール密着性を劣化させるので
通常又は高温加熱は好ましくない。また950℃未
満の温度で加熱するのは粗圧延時の噛込性、圧下
性を悪くし、かつ熱延仕上温度の確保が困難とな
るためである。
次に熱間圧延により所望の板厚としたのち550
〜700℃の高温捲取りを行う。
この高温捲取を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。而して
仕上熱延後二次スケールが発生し、捲取後も成長
し、この間にスケールと地鉄界面にSi，Ｐ，Ｓ，
Cu，Crなどが濃縮し二次スケール密着性を悪く
するので、前述の通りこれらの元素および加熱温
度を限定した。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図に非酸化性雰囲気中でのコイルを冷却す
る装置を示す。第１図においてコイル１は砂２
（シールサンド）が敷かれた作業床３に載置され
ついで密閉カバー４によつて気密状態に置かれ
る。密閉カバー４の側壁４ａに設けられた気体送
給管５ａ，５ｂからはN2ガス、同じく気体送給
管６ａ，６ｂからはArガスが送給される。７ａ
〜７ｄは吹込ノズルを示す。８ａ〜８ｄは開閉バ
ルブ、９ａ〜９ｂはN2用、１０ａ〜１０ｂはAr
ガス用の排気管である。
550〜700℃で捲取られたコイルは適宜な搬送手
段で前記作業床３上に搬送され、ついで密閉カバ
ー４でコイル１を覆う。図に示す通り作業床３に
は前述のシールサンド２があるので密閉カバー４
内の気密性は充分に保持される。サンドシールの
代りに水でシールしてもよい。ついで図示してい
ない供給源から吹込ノズル７ａ，７ｂを介してた
とえばN2ガスを吹込むと排気管９ａ，９ｂから
空気が排出され密閉カバー４内はN2ガスでみた
される。ついでバルブ８ａ，８ｂおよび１１ａ，
１１ｂを閉じる。
冷却の必要によつてはバルブ８ａ，８ｂを常開
とし、バルブ１１ａ，１１ｂを開き排気管９ａ，
９ｂから常に排気されるようにしておいても差し
つかえない。N2ガス吹込中はArガス用のバルブ
８ｃ，８ｄ；排気用のバルブ１１ｃ，１１ｄは当
然のことながら閉状態とする。
このように不活性ガス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の含有量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。
実施例 １
第１表に示す成分組成の中炭素鋼を溶製後連続
鋳造し、熱鋼片状態のまま加熱炉に装入し、950
〜1200℃で加熱後熱延仕上温度820℃、捲取温度
575〜650℃で捲取後第１図の装置に装入し、N2
ガスを300／分の流量で30分間吹込み、その後
流量を50／分とし、コイル表面温度が350℃に
達する迄吹込んだ（本発明）。比較材として同一
成分で加熱温度を1280℃にしたものを上と同様の
熱延仕上および捲取温度で捲取つた後N2ボツク
スに装入したもの（比較材Ａ）、または大気中で
ブロワー冷却した（比較材Ｂ）。その後コイル長
手方向中央部より試験材を採取し、巾方向端部と
中央部より曲げ試験片を取り、その試験結果を第
２表に示す。スケール密着性は曲げ半径1.5tで90
゜曲げ試験後曲げ部にセロテープを貼付け、テー
プをはがした後の試験片曲げ部のスケール剥離状
況を目視で観察し、スケールの剥離がなく良好：
〇印、わずかに剥離：△印、やや剥離多い：×
印、きわめて剥離が多く悪い：××印で表示し
た。
(Industrial Application Field) The present invention relates to a method for producing hot rolled steel sheets for pipes, drums, formed steel and other general processing. (Prior art) Steel plates manufactured by hot rolling continuously cast slabs are
Due to the poor adhesion of secondary scale, scale dust may be generated in subsequent processes, which may cause environmental problems, or the edges with particularly poor adhesion may become unusable, or surface treatments such as bonding after pickling may be necessary. After this process, the method was used to form products such as drums and pipes, and then coat the surface. (Objective of the invention) The present invention does not generate dust in the post-process, can be used for processing the entire width of the coil, does not require pickling or bonding, and can be immediately molded and surface coated by the processing manufacturer. An object of the present invention is to provide a method for producing a hot-rolled steel sheet with excellent scale adhesion. (Structure and operation of the invention) As mentioned above, hot-rolled steel sheets manufactured using continuously cast slabs have poor scale adhesion and require various surface treatments. As a result of research and development of a hot-rolled steel sheet with excellent scale adhesion that does not require a complex 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%,
Si0.05% or less, Mn0.20-1.00%, P0.020% or less,
S0.020% or less, Cu0.05% or less, Cr0.05% or less,
After melting steel with Al 0.08% or less and the remainder consisting of Fe and unavoidable impurities, the hot steel slab obtained by continuous casting is immediately charged into a heating furnace, or once it is made into a cold slab, it is loaded into a heating furnace. The coil is heated, extracted at 950-1200℃, hot-rolled, and wound at 550-700℃.
The present invention provides a method for producing a hot-rolled steel sheet with excellent scale adhesion, which comprises cooling to 350°C in a non-oxidizing atmosphere consisting of N 2 gas, Ar gas, or a mixture thereof. This will be explained in more detail below. The reason for limiting the components in the present invention is to provide a steel sheet that is suitable for processing purposes targeted by the present invention. The reason for setting C0.03 to 0.25% is to give the hot rolled steel sheet according to the present invention properties suitable for use in pipes, drums, molded steel, automobile frames, cooking pots, etc. Low carbon to medium carbon steel is suitable. In finished products, most of C becomes Fe 3 C (cementite), which worsens scale adhesion, so it is desirable to have it as low as possible, but automobile frames, building materials, pipes, etc. require strength, so to satisfy both, 0.25 % is the upper limit, and the C component suitable for drum materials etc. is limited to 0.03%, which is why the lower limit of the C component in the present invention is set to 0.03%. Next, the reason why Si is set to 0.05% or less is that if it exceeds this level, it will impair the properties of the steel sheet that is the objective of the present invention.Si is unavoidable because it is used for deoxidation in Al-killed and Al-Si killed steels. contained in In the present invention, the lower the Si content, the better, and the range that does not impair the purpose is 0.05% 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
This is because both P and S concentrate at the interface between the scale and the steel base during heating and hot rolling, impairing secondary 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 should be set to 0.020%, taking into account the economic tolerance.
% or less and should be determined appropriately. In addition, the reason why Al is set to 0.08% or less is that the inclusion of Al is unavoidable when deoxidizing Al for the purpose of manufacturing steel sheets, and as a result of investigating the limit of the effect on the purpose, good results were found up to 0.08%. This is because it was done.
However, if it exceeds 0.08%, economic problems will occur. Therefore, in the present invention, the Al content is set to 0.08% or less. Similarly, the reason for setting Cu to 0.05% or less and Cr to 0.05% or less is that both Cu and Cr concentrate at the interface between the scale and the steel base during heating and hot rolling, impairing secondary scale adhesion. The limit is 0.05%. Furthermore, like Cu and Cr, Sn, As, and Ni are also elements that deteriorate secondary scale adhesion, so it is not preferable to include them, but they are permissible as long as they are included as unavoidable impurities. In the present invention, the steel having the above-mentioned components is melted in a top-, bottom-blowing, or top-bottom blowing converter after the well-known preliminary treatment of molten iron, such as dephosphorization, sulfur removal, and silicone removal, is carried out as necessary. It is 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 apparatus is charged into a heating furnace as it is in the form of a hot steel sheet, or once it is in the form of a cold slab, it is reheated and hot rolled. The heating temperature (extraction temperature) in is in the temperature range of 950 to 1200°C. The reason for performing low-temperature heating at 950 to 1200℃ is that heating above 1200℃ causes the formation of Si, P, S,
Normal or high-temperature heating is undesirable because Cu, Cr, Sn, As, and the like are concentrated at the interface between the steel slab and the scale or on the surface of the steel slab, and also on the surface of the hot-rolled steel sheet, deteriorating secondary scale adhesion. Furthermore, heating at a temperature lower than 950°C worsens the biting and rolling properties during rough rolling, and makes it difficult to secure the hot rolling finishing temperature. Next, after hot rolling to the desired thickness, 550
Perform high temperature winding at ~700℃. 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℃, but below 570℃, it transforms into Fe 3 O 4
It transforms into 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 a favorable result. This is the reason why the lower limit temperature is set at 550°C. That is, below 550°C, 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. Secondary scale is generated after finishing hot rolling and grows after rolling, and during this time, Si, P, S,
Since Cu, Cr, etc. concentrate and deteriorate secondary scale adhesion, these elements and heating temperature were limited as described above. The reason why we limited the cooling end temperature in a non-oxidizing atmosphere to 350℃ is that the iron oxide FeO on the surface of the coil wound at 550 to 700℃ has a transformation temperature (approx.
After transforming into Fe 3 O 4 at temperatures below 570℃, scale adhesion becomes poor when exposed to air at high temperatures.
Since it becomes Fe 2 O 3 , the temperature should be 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. FIG. 1 shows an apparatus for cooling a coil in a non-oxidizing atmosphere. In Figure 1, coil 1 is sand 2
It is placed on a work floor 3 covered with (seal sand) and then placed in an airtight state with an airtight cover 4. N2 gas is supplied from gas supply pipes 5a and 5b provided on the side wall 4a of the airtight cover 4, and Ar gas is supplied from gas supply pipes 6a and 6b. 7a
~7d indicates the blowing nozzle. 8a to 8d are on/off valves, 9a to 9b are for N2 , 10a to 10b are for Ar
This is an exhaust pipe for gas. The coil wound at 550 to 700° C. is conveyed onto the work floor 3 by suitable conveying means, and then the coil 1 is covered with a sealing cover 4. As shown in the figure, since the aforementioned seal sand 2 is on the work floor 3, the airtight cover 4
The airtightness inside is maintained sufficiently. Water sealing may be used instead of sand sealing. Then, for example, N2 gas is blown from a supply source (not shown) through the blowing nozzles 7a and 7b, and air is exhausted from the exhaust pipes 9a and 9b, and the inside of the airtight cover 4 is filled with N2 gas. Then valves 8a, 8b and 11a,
Close 11b. Depending on the need for cooling, valves 8a and 8b are normally open, valves 11a and 11b are opened, and exhaust pipes 9a and 8b are opened.
There is no problem even if the air is always exhausted from 9b. During the N 2 gas blowing, the Ar gas valves 8c and 8d and the exhaust valves 11c and 11d are naturally closed. When the coil is cooled in an inert gas atmosphere in this way, the coil surface, especially the top, bottom, and both edges, which are easily oxidized and generate secondary scale with a high content of Fe 2 O 3 , are exposed to 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. Example 1 Medium carbon steel with the composition shown in Table 1 was melted and continuously cast, charged into a heating furnace in the hot billet state, and heated to 950
After heating at ~1200℃, hot rolling finishing temperature 820℃, winding temperature
After winding it up at 575-650℃, charge it into the equipment shown in Figure 1, and add N 2
Gas was blown in at a flow rate of 300/min for 30 minutes, and then at a flow rate of 50/min until the coil surface temperature reached 350°C (invention). As a comparison material, a material with the same composition heated to 1280℃ was hot-rolled and rolled at the same winding temperature as above, and then charged into an N2 box (comparative material A), or a material was heated using a blower in the air. It was cooled (comparative material B). Thereafter, a test material was taken from the center in the longitudinal direction of the coil, and bending test pieces were taken from the ends and the center in the width direction, and the test results are shown in Table 2. Scale adhesion is 90 at bending radius of 1.5t
゜After the bending test, cellophane tape was attached to the bent part, and after the tape was removed, the condition of scale peeling on the bent part of the test piece was visually observed, and there was no peeling of scale, which was good:
○ mark, slight peeling: △ mark, slightly peeling: ×
mark, extremely peeling and poor: indicated by XX mark.
【表】【table】
【表】
実施例 ２
第３表に示す成分組成の低合金鋼を実施例１と
同じ方法で溶製、熱延、冷却を行つた。二次スケ
ールの密着性を曲げ試験で行つた結果を第４表に
示す。[Table] Example 2 Low alloy steel having the composition shown in Table 3 was melted, hot rolled and cooled in the same manner as in Example 1. Table 4 shows the results of a bending test to determine the adhesion of the secondary scale.
【表】【table】
【表】
以上の実施例から本発明による熱延鋼板はスケ
ール密着性が極めて良く、特に端部は飛躍的に向
上することが判る。
実施例 ３
第５表に示す成分組成の二種類の低合金鋼を実
施例１と同じ方法で溶製熱延、冷却を行つた。二
次スケールの密着性を曲げ試験で行つた結果を第
６表に示す。両成分系ともほぼ同じ結果であつ
た。[Table] From the above examples, it can be seen that the hot rolled steel sheet according to the present invention has extremely good scale adhesion, and the scale adhesion is particularly improved dramatically at the edges. Example 3 Two types of low alloy steels having the compositions shown in Table 5 were hot-rolled and cooled in the same manner as in Example 1. Table 6 shows the results of a bending test to determine the adhesion of the secondary scale. The results were almost the same for both component systems.
【表】【table】
【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、後工程でのスケ
ールによる粉塵が発生せず、コイル全幅にわたり
スケール密着性が良好で、また酸洗やボンデ処理
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 generate dust due to scale in the subsequent process, and has good scale adhesion over the entire width of the coil. It also does not require pickling or bonding, and can be used to manufacture pipes, drums, etc., and can be painted as necessary after forming into groove steel and angle steel. , extremely economical. The present invention provides a means for economically producing such hot rolled steel sheets, and is a highly practical method.
第１図は本発明の方法を実施するための実施例
装置の概略説明図である。
１…コイル、２…シールサンド、３…作業床、
４…密閉カバー、５ａ〜５ｂ…気体送給管（N2
用）、６ａ，６ｂ…気体送給管（Arガス用）、７
ａ〜７ｂ…吹込ノズル、８ａ〜８ｄ…開閉バル
ブ、９ａ〜９ｂ…排気管（N2ガス用）、１０ａ〜
１０ｂ…排気管（Arガス用）、１１ａ〜１１ｄ…
開閉バルブ。
FIG. 1 is a schematic explanatory diagram of an embodiment apparatus for carrying out the method of the present invention. 1...Coil, 2...Seal sand, 3...Working floor,
4... Airtight cover, 5a-5b... Gas supply pipe (N 2
), 6a, 6b...Gas feed pipe (for Ar gas), 7
a~7b...Blowing nozzle, 8a~8d...Opening/closing valve, 9a~9b...Exhaust pipe (for N2 gas), 10a~
10b...Exhaust pipe (for Ar gas), 11a to 11d...
Open/close valve.
Claims (1)
1.00％、P0.020％以下、S0.020％以下、Cu0.05％
以下、Cr0.05％以下、Al0.08％以下、で残りが
Feおよび不可避不純物からなる鋼を溶製後、連
続鋳造して得た熱鋼片を直ちに加熱炉に装入する
かもしくは一旦冷片としたのち加熱炉に装入し
950〜1200℃で抽出して熱間圧延を行い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%, Si0.05% or less, Mn0.20~
1.00%, P0.020% or less, S0.020% or less, Cu0.05%
Below, Cr 0.05% or less, Al 0.08% or less, and the rest
After melting steel containing Fe and unavoidable impurities, the hot steel slab obtained by continuous casting is immediately charged into a heating furnace, or once it is turned into a cold slab, it is charged into a heating furnace.
Extracted at 950-1200℃ and hot rolled to 550-700℃
A method for producing a hot-rolled steel sheet with excellent scale adhesion, characterized by cooling a coil wound at ℃ to 350℃ in a non-oxidizing atmosphere consisting of N 2 gas, Ar gas, or a mixture thereof. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13035683A JPS6024320A (en) | 1983-07-19 | 1983-07-19 | Production of hot rolled steel sheet having excellent scale adhesion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13035683A JPS6024320A (en) | 1983-07-19 | 1983-07-19 | Production of hot rolled steel sheet having excellent scale adhesion |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6024320A JPS6024320A (en) | 1985-02-07 |
| JPS625213B2 true JPS625213B2 (en) | 1987-02-03 |
Family
ID=15032423
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13035683A Granted JPS6024320A (en) | 1983-07-19 | 1983-07-19 | Production of hot rolled steel sheet having excellent scale adhesion |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6024320A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63252812A (en) * | 1987-04-09 | 1988-10-19 | Denson Kk | Object reversing method |
| JPS6433014U (en) * | 1987-08-21 | 1989-03-01 |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6077922A (en) * | 1983-10-05 | 1985-05-02 | Nippon Steel Corp | Production of hot-rolled steel plate having high adhesion to scale |
| JPH01159348A (en) * | 1987-12-16 | 1989-06-22 | Kawasaki Steel Corp | H-shape steel having tight scale and its production |
| JP5520086B2 (en) * | 2010-03-09 | 2014-06-11 | 株式会社神戸製鋼所 | High Si content steel sheet with excellent surface properties and method for producing the same |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5081909A (en) * | 1973-11-27 | 1975-07-03 | ||
| 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 |
-
1983
- 1983-07-19 JP JP13035683A patent/JPS6024320A/en active Granted
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5081909A (en) * | 1973-11-27 | 1975-07-03 | ||
| 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 |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63252812A (en) * | 1987-04-09 | 1988-10-19 | Denson Kk | Object reversing method |
| JPS6433014U (en) * | 1987-08-21 | 1989-03-01 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6024320A (en) | 1985-02-07 |
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