JPS6111290B2 - - Google Patents
Info
- Publication number
- JPS6111290B2 JPS6111290B2 JP56001411A JP141181A JPS6111290B2 JP S6111290 B2 JPS6111290 B2 JP S6111290B2 JP 56001411 A JP56001411 A JP 56001411A JP 141181 A JP141181 A JP 141181A JP S6111290 B2 JPS6111290 B2 JP S6111290B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- temperature
- annealing
- tin plate
- soft
- 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 57
- 239000010959 steel Substances 0.000 claims description 57
- 238000000137 annealing Methods 0.000 claims description 44
- 239000005028 tinplate Substances 0.000 claims description 42
- 238000001816 cooling Methods 0.000 claims description 20
- 238000004519 manufacturing process Methods 0.000 claims description 18
- 238000009749 continuous casting Methods 0.000 claims description 15
- 230000009466 transformation Effects 0.000 claims description 4
- 239000010960 cold rolled steel Substances 0.000 claims description 3
- 238000000034 method Methods 0.000 description 22
- 239000000463 material Substances 0.000 description 16
- 238000005098 hot rolling Methods 0.000 description 13
- 238000002474 experimental method Methods 0.000 description 10
- 239000000203 mixture Substances 0.000 description 7
- 238000005096 rolling process Methods 0.000 description 7
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 6
- 238000005554 pickling Methods 0.000 description 6
- 229910000859 α-Fe Inorganic materials 0.000 description 6
- 229910001567 cementite Inorganic materials 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000007747 plating Methods 0.000 description 3
- 230000001376 precipitating effect Effects 0.000 description 3
- 238000005496 tempering Methods 0.000 description 3
- 229910001208 Crucible steel Inorganic materials 0.000 description 2
- 229910000655 Killed steel Inorganic materials 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000004931 aggregating effect Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000010420 art technique Methods 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000004804 winding 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
- 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 Sheet Steel (AREA)
- Heat Treatment Of Steel (AREA)
Description
本発明は連続焼鈍による軟質ぶりき板の製造方
法に係り、特に連続鋳造アルミキルド鋼を使用す
る連続焼鈍法による耐食性および加工性にすぐれ
た軟質ぶりき板の製造方法に関する。
ぶりき板は、その調質度をJIS G3303におい
て、ロツクウエルＴ硬さ（ＨR30T）の値をもつ
て表わすことが規定され、軟質のものからＴ―１
（ＨR30T：46〜52）、Ｔ―２（50〜56）、Ｔ―２１／２
（52〜58）、Ｔ―３（54〜60）、Ｔ―４（58〜64）、
Ｔ―５（62〜68）およびＴ―６（67〜73）に区分
されている。このうちＴ―３以下の軟質板は、従
来主として箱焼鈍法による長時間焼鈍によつて製
造されており、生産能率および熱効率は低い。
かかる軟質ぶりき板の製造に連続焼鈍を用いれ
ば、生産能率、熱効率を改善し、更に鋼板形状を
も良くすることができるが、連続焼鈍法では箱焼
鈍法に匹敵する軟質ぶりき板が得られないとして
実用化されるに至つていない現状である。軟質ぶ
りき板の製造に連続焼鈍法が実用化されなかつた
大きな理由の一つは、適正素材と関連する熱延条
件、焼鈍条件が確立されていなかつたことによる
ものである。
連続焼鈍法によれば前記生産能率、熱効率の改
善のみならず、箱焼鈍に比して鋼帯に付与される
熱履歴を鋼帯長手方向に対して均一にでき、その
結果鋼帯長手方向の材質変動を小さくできるとい
う利点がある。すなわち、成分変動の少いぶりき
板用材としては連続鋳造鋼が最も適しており、連
続鋳造鋼を使用する連続焼鈍法による軟質ぶりき
の製造法の確立が期待されていた。しかし従来、
連続鋳造鋼を用いると、一般に焼鈍後の結晶粒が
微細化し硬質になる傾向があり軟質ぶりき板の製
造が困難であつた。
連続鋳造鋼を用いて軟質ぶりき原板を製造する
従来技術としては特開昭50―121118号にて開示さ
れたものがある。この方法は同公報実施例によれ
ば次の如くである。すなわち、Ｃ：0.03〜0.07
％、Mn：0.2〜0.4％、Al：0.01〜0.09％、Ｎ：
〓〓〓〓
0.003〜0.014％を含む連続鋳造スラブを熱間圧延
における仕上げ温度を720〜790℃、巻取温度を
580〜710℃とし、更に冷間圧延した後、均熱温度
640〜680℃で焼鈍し、その後11〜14℃/secの冷却
速度にて常温まで冷却するか、更にその後300〜
5500℃に再加熱して過時効処理する方法であり、
この方法によつて調質度Ｔ―１〜Ｔ―３の軟質ぶ
りき板を製造することができるとしている。
しかし、この方法の大きな欠点は熱延後の巻取
温度が高いことである。通常熱延鋼帯の巻取温度
は500〜580℃であるが、この方法は好ましい温度
範囲として580〜680℃とし、実施例には前記の如
く580〜710℃の高温巻取りが示されている。熱延
鋼帯の巻取温度が高くなると、表面に生成される
酸化被膜がマグネタイト（Fe3O4）を主成分とし
て緻密になるので脱スケール性が極端に低下す
る。そのため通常の熱延板と同程度の酸洗速度で
酸洗すると、脱スケール不良となり、最終製品に
表面欠陥が発生し易くなる。元来ぶりき板は表面
性状が極めて重要な製品であるので表面欠陥は致
命的な欠陥となる。そのため従来は580℃以上の
高温で巻取つた熱延鋼帯は、その脱スケールの酸
洗時に酸洗ラインの通板速度を落して操業してい
るが、このこと自体は生産性の低下となるので工
業生産では大きな不利益を招来することとなる。
更に他の一つの問題は、巻取温度が高いと、熱
延板中のカーバイドが通常の低温巻取材の如くフ
エライト中に微細に析出せず粒界に凝集した組織
になり、この組織は冷延、焼鈍、調質圧延を経て
めつき工程まで保持されるので、ぶりき板の耐食
性を著しく劣化させる結果となることである。
かくの如く、連続鋳造材による連続焼鈍法をと
る軟質ぶりき板製造の従来技術には、生産性の低
下、表面性状の劣化等の問題がある。かかる問題
があるにも拘らず軟質ぶりき板を連続焼鈍法で製
造するに当り熱延鋼帯を600℃以上の高温で巻取
る理由は、鋼中のＮをAlNとしてセメンタイトと
共に熱延板中に粗大に凝集析出させることによ
り、フエライト中の固溶Ｎを減少させて結晶粒の
成長を促進し軟質ぶりき原板を製造できる利点が
あるからである。
かくの如く、連続鋳造材、連続焼鈍法による軟
質ぶりき板の従来の製造方法には、幾多の未解決
の問題が残されており、未だ実用の域には達して
いない現状にある。
本発明の目的は、連続鋳造材、連続焼鈍法によ
る軟質ぶりき板製造の前記従来技術の欠点を克服
し、表面性状、耐食性にすぐれた軟質ぶりき板を
低コストで製造し得る製造方法を提供するにあ
る。
本発明の要旨とするところは次の如くである。
すなわち、重量比にてＣ：0.01〜0.03％、
solAl：0.003〜0.02％、Ｎ：0.004％以下を含む鋼
を連続鋳造にてスラブとする工程と、前記スラブ
を熱間圧延後450℃以上550℃以下の温度で巻取つ
た後酸洗し冷間圧延する工程と、前記冷延鋼帯を
連続焼鈍炉にて680℃以上A1変態点以下の温度に
20秒以上保持した後500℃以下の温度まで10〜500
℃/secの冷却速度で冷却する工程と、前記冷却し
た鋼帯を350〜500℃の温度範囲に30秒以上保持し
た後冷却する工程と、を有して成ることを特徴と
する連続焼鈍による軟質ぶりき板の製造方法であ
る。
前述の如く、従来熱延鋼帯を高温にて巻取る理
由は、鋼中のＮをAlNとしてセメンタイトと共に
粗大に凝集析出させることによつてフエライト中
の固溶Ｎを減少させ結晶粒の成長を促進すること
にあつたが、本発明者らは巻取温度を高温にせず
とも、従つて固溶ＮをAlNとして熱延板中に析出
させなくても、Ｃ、AlおよびＮ量を適当量に調
整することにより結晶粒の成長性がよく、軟質の
ぶりき原板が製造できることを見出し、多くの実
験を重ねた結果本発明を得たものである。
本発明の構成要件を得るに至つた実験結果につ
いて記載する。
(A) 先ず適正なsolAl量とＮ量との関係を明らか
にするためＣ：0.02％の鋼を基準としてsolAl
量を0.003％から0.080％まで変化させ、Ｎを
0.0018％から0.0060％まで変化させたAlキルド
鋼を転炉で溶製し、連続鋳造でスラブとした
後、熱延条件中熱延仕上げ温度を860〜890℃、
巻取温度を520℃として28mm厚さの熱延鋼帯と
し、酸洗後0.32板厚に冷間圧延した。この冷延
鋼板を710℃に加熱して再結晶焼鈍し、該温度
から500℃まで50℃/secの冷却速度で急冷後、
400℃で１分間保持する過時効処理を含む連続
焼鈍を行ない、しかる後1.5％の調質圧延を施
し、これを電気めつきラインを通して製品とし
〓〓〓〓
た。かくして得た多く供試材の硬さを測定した
結果をsolAl量およびＮ量と共に第１図に示
す。第１図において、ＨR30Tが59以下の調質
度Ｔ―３以下の軟質板となつたのは斜線枠内の
供試材であり、この枠内の供試材のsolAll、Ｎ
量はそれぞれ0.02％以下および0.004％以下の
範囲であつた。すなわち、solAlが0.02％を越
える場合、もしくはＮ量が0.004％を越える範
囲では硬度が著しく高くなり、軟質ぶりき板を
製造できないことが判明した。これは、固溶
Ｎ，AlおよびAlNの増加に伴ない連続焼鈍の如
き短時間焼鈍では結晶粒の成長性が著しく阻害
され、その結果軟質にならないためと考えられ
る。
この実験でsolAl量を0.003％以上としたの
は、solAlが0.003％より少い場合には連続鋳造
の鋳込時にCO気泡が発生し、鋳込作業を困難
にするばかりでなく、スラブにブローホールが
多発し、製品の表面性状を著しく悪化させるか
らである。この実験より使用する連続鋳造鋼は
solAl：0.003〜0.02％、Ｎ：0.004％以下に限定
すべきであることが判明した。
(B) 次に本発明者らは軟質ぶりき板を得るため
に、solAl、Ｎ量のほかにＣを適正にすべきで
あるとの考えから次の実験を行つた。すなわ
ち、solAl：0.01％、Ｎ：0.003％を基準として
Ｃ量を0.006％から0.06％まで変化させて(A)と
同一条件で実験した。この実験は焼鈍時に過時
効処理を施す場合()と、施さない場合()と
についてそれぞれ実験し、それぞれの結果の硬
さとＣ量との関係を第２図に示した。
第２図より明らかな如く、400℃で１分間保
持する過時効処理を施さない鋼板は全範囲に亘
つてＨR30Tが60を越し、Ｔ―３に該当するも
のが得られなかつた。一方、過時効処理した鋼
板の硬さはＣ量と共に特異な挙動を示し、Ｃ量
が0.01〜0.03％の範囲でＨR30Tが59以下の軟質
となることが判明した。この理由は、Ｃ量が
0.03％を越すとセメンタイト量が増加するので
当然硬くなり、0.01％未満では急冷後の固溶Ｃ
の過飽和度が小さいので過時効が十分進行しな
いために軟質とならない。Ｃ量が0.01〜0.03％
の範囲では、セメンタイト量が少く、かつ十分
過時効処理の効果が現れることにより最も軟質
となるものと考えられる。従つて連続鋳造鋼中
のＣ量は0.01〜0.03％に限定すべきであること
が判明した。
(C) 連続鋳造鋼の硬度に及ぼす熱延鋼帯の巻取温
度の影響を調査する実験を行つた。前記(A)、(B)
の実験において熱延鋼帯の巻取温度を520の低
温にてもＴ―３に該当する軟質ぶりき原板を得
ることができることを確認したが、ここでは
(A)、(B)にて限定することができた成分を有する
鋼として、Ｃ：0.02％、solAl：0.01％、Ｎ：
0.003％のNo.１鋼と、限定外のＣ：0.02％、
solAl：0.04％、Ｎ：0.05％のNo.２鋼を用い、
巻取温度の影響をみるために熱延後の巻取温度
を500〜700℃に変化させたほかは(A)、(B)と同一
条件でぶりきの製造試験を実施した。
結果は第３図に示す如く、(A)，(B)にて限定し
た成分外のNo.２鋼では巻取温度の低下と共に硬
度は急激に上昇するが、限定内のNo.１鋼では
550℃以下で巻取つても硬度の上昇が認められ
なかつた。従つて(A)、(B)にて限定した成分を有
する連続鋳造鋼の場合には熱延後のあることが
判明した。しかし巻取温度が過時に低くなると
熱延板の形状が劣化するので本発明では450℃
以上550℃以下の温度に限定した。
しかしながら素材の成分及び熱延後の巻取温
度を限定するだけでは十分軟質のぶりき板が得
られず適切な焼鈍条件が必要である。連続焼鈍
によつて軟質な鋼板を得る先行技術としては特
公昭33―2116号にて開示され、既に公用されて
いる再結晶焼鈍後過時効処理する方法がある。
本発明者らは上記先行技術を基本として(A)、(B)
にて限定することができた鋼成分および上記巻
取温度550℃以下を条件として軟質ぶりき板を
得るための最高焼鈍条件を次の(A)にて記載する
実験にて見出すことができた。
(A) 再結晶焼鈍条件を求めるために(A)、(B)にて限
定した適正成分鋼を使用し、焼鈍時間を6600〜
850℃の間に温度を変えて実験し、焼鈍後の硬
度ＨR30Tを測定した。なお、該焼鈍時間にお
ける保持時間はすべて20秒とした。結果は第４
図に示すとおりである。
第４図より明らかなとおり、焼鈍温度は680
℃以上であればＨR30Tが59以下の十分軟質の
鋼が得られることが判明した。更に保持時間に
〓〓〓〓
ついて調査したところ680℃以上の場合20秒以
上であれば十分再結晶し軟化することが判明し
た。しかし焼鈍温度がA1変態点を越すとパー
ライト組織が生成し耐食性が劣化するので上限
をA1変換点の温度に限定すべきである。
(E) 再結晶焼鈍後の急冷条件については、その後
の過時効処理時間を短縮するために10℃/sec以
上500℃/sec以下の冷却速度で500℃以下の温度
まで冷却する必要がある。その理由は次の如く
である。すなわち、10℃/sec未満の冷却速度で
は、冷却中にセメンタイトが析出し、Ｃの過飽
和度が低くなるためその後の過時効が十分進行
しない。また、500℃/secを越す急速冷却を行
うと、ぶりき板の表面形状が著しく悪化するの
で好ましくない。更に500℃を越す高い温度で
急冷を中止すると、その温度でのフエライト中
のＣの平衡溶解度近傍までのＣの固溶度が減少
し、この場合も過時効が進行しない。従つて再
結晶焼鈍後の急速冷却条件は10〜500℃/secの
冷却速度で500℃以下の温度まで冷却すべきで
ある。
(F) 次に過時効処理の条件については、次の理由
で350〜500℃の温度範囲に30秒以上保持すべき
である。すなわち、350℃未満の温度ではＣの
拡散速度が小さく過時効が進行せず、また500
℃を越す高い温度では、Ｃの固溶限が大きいの
で固溶Ｃ量を低く抑えることができず、更に保
持時間が30秒未満では十分過時効が完了しない
からである。
上記(A)、(B)、(C)、(D)、(E)、(F)にて限定した条
件で、連続焼鈍および過時効処理した後、調質
圧延し、その後錫めつきを施したぶりき板はＴ
―３以下の十分軟質で加工性のすぐれた製品を
得ることができる。
実施例 １
第１表に示す如き成分の鋼を転炉で溶製し、供
試材No.１〜14について仕上温度860〜890℃、巻取
温度520℃で板厚2.6mmに熱間圧延後、板厚0.32mm
まで冷間圧延した。
この冷延板を710℃の温度に20秒保持して連続
焼鈍を行い、次に50℃/secの冷却速度で400℃ま
で冷却し、400℃に30秒保持した
The present invention relates to a method of manufacturing a soft tin plate by continuous annealing, and more particularly to a method of manufacturing a soft tin plate with excellent corrosion resistance and workability by a continuous annealing method using continuously cast aluminum killed steel. JIS G3303 stipulates that the degree of tempering of tin plate is expressed by the Rockwell T hardness (H R 30T), which ranges from soft to T-1.
(H R 30T: 46-52), T-2 (50-56), T-21/2 (52-58), T-3 (54-60), T-4 (58-64),
It is divided into T-5 (62-68) and T-6 (67-73). Among these, soft plates of T-3 and below are conventionally manufactured mainly by long-time annealing using the box annealing method, and the production efficiency and thermal efficiency are low. If continuous annealing is used to manufacture such soft tin plate, production efficiency and thermal efficiency can be improved, and the shape of the steel sheet can also be improved, but continuous annealing method cannot produce soft tin plate comparable to box annealing method. At present, it has not been put into practical use because it cannot be done. One of the major reasons why the continuous annealing method has not been put to practical use in the production of soft tin plate is that appropriate materials and related hot rolling and annealing conditions have not been established. The continuous annealing method not only improves the production efficiency and thermal efficiency, but also makes the thermal history imparted to the steel strip uniform in the longitudinal direction of the steel strip compared to box annealing. This has the advantage of reducing material variation. In other words, continuous casting steel is most suitable as a material for tinplate plates with little variation in composition, and it was hoped that a method for manufacturing soft tinplate by continuous annealing using continuous casting steel would be established. However, conventionally,
When continuous casting steel is used, the crystal grains generally tend to become fine and hard after annealing, making it difficult to produce soft tin plate. A conventional technique for manufacturing a soft tin plate using continuous casting steel is disclosed in Japanese Patent Application Laid-Open No. 121118/1983. This method is as follows according to the example of the publication. That is, C: 0.03-0.07
%, Mn: 0.2-0.4%, Al: 0.01-0.09%, N:
〓〓〓〓
Continuously cast slabs containing 0.003~0.014% are hot rolled at a finishing temperature of 720~790℃ and a coiling temperature of 720~790℃.
After further cold rolling at 580-710℃, soaking temperature
Annealed at 640-680℃, then cooled to room temperature at a cooling rate of 11-14℃/sec, or further after that at 300-680℃
This is a method of overaging treatment by reheating to 5500℃,
It is said that by this method, it is possible to produce soft tin plate with a tempering degree of T-1 to T-3. However, a major drawback of this method is that the coiling temperature after hot rolling is high. The coiling temperature of hot-rolled steel strip is usually 500 to 580°C, but the preferred temperature range for this method is 580 to 680°C, and as mentioned above, high temperature coiling of 580 to 710°C is shown in the examples. There is. When the coiling temperature of the hot-rolled steel strip increases, the oxide film formed on the surface becomes dense and consists mainly of magnetite (Fe 3 O 4 ), resulting in extremely poor descaling performance. Therefore, if pickling is performed at the same pickling speed as for ordinary hot-rolled sheets, descaling will be insufficient and surface defects will easily occur in the final product. Since tinplate is a product for which surface quality is extremely important, surface defects can be fatal. For this reason, hot-rolled steel strips that are conventionally coiled at high temperatures of 580°C or higher are operated by reducing the pickling speed during pickling to descale them, but this in itself leads to a decrease in productivity. This results in a major disadvantage in industrial production. Another problem is that when the coiling temperature is high, the carbide in the hot-rolled sheet does not precipitate finely in the ferrite like in ordinary low-temperature coiled material, but forms a structure that aggregates at the grain boundaries. Since the steel is kept through rolling, annealing, and temper rolling until the plating process, the corrosion resistance of the tin plate is significantly deteriorated. As described above, the conventional technology for manufacturing soft tin plate using continuous annealing using continuous casting materials has problems such as decreased productivity and deterioration of surface quality. Despite these problems, the reason why hot-rolled steel strips are rolled at a high temperature of 600°C or higher when producing soft tin plate using the continuous annealing method is that the N in the steel is replaced with AlN and the hot-rolled steel strips are mixed with cementite in the hot-rolled sheets. This is because by coarsely aggregating and precipitating ferrite, there is an advantage that solid solution N in ferrite can be reduced and growth of crystal grains can be promoted to produce a soft tin plate. As described above, the conventional manufacturing method of soft tin plate using continuous casting materials and continuous annealing method has many unresolved problems, and the current state is that it has not yet reached the level of practical use. An object of the present invention is to overcome the drawbacks of the conventional techniques of manufacturing soft tin plate using continuous casting materials and continuous annealing, and to provide a manufacturing method that can produce soft tin plate with excellent surface texture and corrosion resistance at low cost. It is on offer. The gist of the present invention is as follows.
That is, C: 0.01 to 0.03% by weight,
A process of continuously casting steel containing solAl: 0.003 to 0.02% and N: 0.004% or less into a slab, and after hot rolling the slab, it is rolled up at a temperature of 450°C or more and 550°C or less, and then pickled and cooled. The step of inter-rolling the cold-rolled steel strip in a continuous annealing furnace to a temperature of 680℃ or higher and lower than the A1 transformation point.
10~500 to a temperature below 500℃ after holding for more than 20 seconds
Continuous annealing characterized by comprising a step of cooling at a cooling rate of ℃/sec, and a step of holding the cooled steel strip at a temperature range of 350 to 500℃ for 30 seconds or more and then cooling it. This is a method for manufacturing soft tin plate. As mentioned above, the reason why hot-rolled steel strips are conventionally coiled at high temperatures is to reduce the solid solution N in the ferrite by coagulating and precipitating the N in the steel as AlN, coarsely agglomerating and precipitating it together with cementite, and thereby inhibiting the growth of crystal grains. However, the present inventors were able to increase the amount of C, Al, and N in appropriate amounts without raising the coiling temperature and without causing solid solution N to precipitate as AlN in the hot rolled sheet. The inventors discovered that by adjusting the temperature, crystal grains can grow well and a soft tin plate can be manufactured, and as a result of many experiments, the present invention was obtained. The experimental results that led to obtaining the constituent elements of the present invention will be described. (A) First, in order to clarify the relationship between the appropriate solAl content and N content, C: solAl based on 0.02% steel.
Varying the amount from 0.003% to 0.080%, N
After melting Al killed steel varying from 0.0018% to 0.0060% in a converter and making it into a slab by continuous casting, the hot rolling finishing temperature was set at 860 to 890℃ during hot rolling conditions.
A hot-rolled steel strip with a thickness of 28 mm was obtained at a coiling temperature of 520°C, and after pickling, it was cold-rolled to a thickness of 0.32. This cold-rolled steel plate was heated to 710°C and recrystallized annealed, and after rapidly cooling from this temperature to 500°C at a cooling rate of 50°C/sec,
Continuous annealing including over-aging treatment held at 400℃ for 1 minute is performed, followed by 1.5% temper rolling, which is then passed through an electroplating line to become a product.
Ta. The results of measuring the hardness of many test materials thus obtained are shown in FIG. 1 together with the amount of solAl and the amount of N. In Fig. 1, the specimens in the shaded frame are soft plates with H R 30T of 59 or less and a tempering degree of T-3 or less.
The amounts ranged from 0.02% and 0.004%, respectively. That is, it has been found that when solAl exceeds 0.02% or when the N content exceeds 0.004%, the hardness becomes extremely high and it is impossible to produce a soft tin plate. This is thought to be because the growth of crystal grains is significantly inhibited in short-time annealing such as continuous annealing due to the increase in solute N, Al, and AlN, and as a result, the steel does not become soft. The reason why the solAl content was set at 0.003% or more in this experiment is because if the solAl content is less than 0.003%, CO bubbles will be generated during continuous casting, which not only makes the casting process difficult, but also blows into the slab. This is because holes occur frequently and the surface quality of the product is significantly deteriorated. From this experiment, the continuous casting steel used is
It was found that the content should be limited to solAl: 0.003-0.02% and N: 0.004% or less. (B) Next, the present inventors conducted the following experiment based on the idea that in addition to solAl and N amounts, C should be appropriate in order to obtain a soft tin plate. That is, an experiment was conducted under the same conditions as (A) by changing the amount of C from 0.006% to 0.06% based on solAl: 0.01% and N: 0.003%. This experiment was conducted with and without overaging treatment during annealing (), and the relationship between hardness and C content for each result is shown in Figure 2. As is clear from FIG. 2, H R 30T exceeded 60 over the entire range of steel sheets that were not subjected to overaging treatment held at 400° C. for 1 minute, and no material corresponding to T-3 was obtained. On the other hand, it was found that the hardness of an over-aged steel sheet exhibits a peculiar behavior with the amount of C, and the steel sheet becomes soft with H R 30T of 59 or less when the amount of C is in the range of 0.01 to 0.03%. The reason for this is that the amount of C is
If it exceeds 0.03%, the amount of cementite will increase and it will naturally become hard, and if it is less than 0.01%, solid solution C after quenching will occur.
Since the degree of supersaturation is small, overaging does not proceed sufficiently and the material does not become soft. C content is 0.01~0.03%
In the range of , it is considered that the amount of cementite is small and the effect of overaging treatment is sufficiently exerted, so that it becomes the softest. Therefore, it has been found that the amount of C in continuously cast steel should be limited to 0.01 to 0.03%. (C) An experiment was conducted to investigate the effect of coiling temperature of hot-rolled steel strip on the hardness of continuously cast steel. (A) and (B) above
In an experiment, it was confirmed that it was possible to obtain a soft tin plate corresponding to T-3 even when the coiling temperature of hot-rolled steel strip was as low as 520℃.
As steel having the components that could be limited in (A) and (B), C: 0.02%, solAl: 0.01%, N:
0.003% No.1 steel and non-limited C: 0.02%,
Using No. 2 steel with solAl: 0.04% and N: 0.05%,
In order to examine the effect of the coiling temperature, a tinplate production test was conducted under the same conditions as in (A) and (B) except that the coiling temperature after hot rolling was varied from 500 to 700°C. The results are shown in Figure 3. For No. 2 steel whose composition is outside the limits specified in (A) and (B), the hardness increases rapidly as the coiling temperature decreases, but for No. 1 steel within the limits.
No increase in hardness was observed even after winding at temperatures below 550°C. Therefore, it has been found that in the case of continuous casting steel having the components specified in (A) and (B), there are certain conditions after hot rolling. However, if the coiling temperature becomes too low, the shape of the hot rolled sheet will deteriorate, so in this invention
The temperature was limited to 550℃ or less. However, it is not possible to obtain a sufficiently soft tin plate simply by limiting the composition of the material and the coiling temperature after hot rolling, and appropriate annealing conditions are required. As a prior art technique for obtaining a soft steel plate by continuous annealing, there is a method of performing overaging treatment after recrystallization annealing, which is disclosed in Japanese Patent Publication No. 33-2116 and is already in public use.
Based on the above prior art, the present inventors have made (A) and (B)
The maximum annealing conditions for obtaining a soft tin plate were found through the experiment described in the following (A), using the steel composition that could be limited by . (A) In order to find the recrystallization annealing conditions, use steel with the appropriate composition specified in (A) and (B), and annealing time 6600~
Experiments were conducted by varying the temperature between 850°C and the hardness H R 30T after annealing was measured. Note that the holding time in the annealing time was all 20 seconds. The result is the 4th
As shown in the figure. As is clear from Figure 4, the annealing temperature is 680
It has been found that a sufficiently soft steel with H R 30T of 59 or less can be obtained if the temperature is above ℃. Further retention time〓〓〓〓
Upon investigation, it was found that at 680°C or higher, 20 seconds or more can sufficiently recrystallize and soften the material. However, if the annealing temperature exceeds the A1 transformation point, a pearlite structure will be formed and the corrosion resistance will deteriorate, so the upper limit should be limited to the temperature of the A1 transformation point. (E) Regarding the rapid cooling conditions after recrystallization annealing, it is necessary to cool to a temperature of 500°C or less at a cooling rate of 10°C/sec or more and 500°C/sec or less in order to shorten the subsequent overaging treatment time. The reason is as follows. That is, at a cooling rate of less than 10° C./sec, cementite precipitates during cooling and the degree of supersaturation of C becomes low, so that subsequent overaging does not proceed sufficiently. Furthermore, if the cooling rate exceeds 500°C/sec, the surface shape of the tin plate will deteriorate significantly, which is not preferable. Furthermore, if the rapid cooling is stopped at a temperature higher than 500°C, the solid solubility of C decreases to near the equilibrium solubility of C in ferrite at that temperature, and in this case too, overaging does not proceed. Therefore, the rapid cooling conditions after recrystallization annealing should be cooling to a temperature of 500°C or less at a cooling rate of 10 to 500°C/sec. (F) Next, regarding the conditions for overaging treatment, the temperature should be maintained in the range of 350 to 500°C for 30 seconds or more for the following reasons. In other words, at temperatures below 350°C, the diffusion rate of C is small and overaging does not proceed;
At a high temperature exceeding .degree. C., the solid solubility limit of C is large, so the amount of solute C cannot be kept low, and if the holding time is less than 30 seconds, overaging will not be completed sufficiently. After continuous annealing and overaging treatment under the conditions specified in (A), (B), (C), (D), (E), and (F) above, skin pass rolling is performed, followed by tin plating. The applied tin plate is T
It is possible to obtain a product with a rating of -3 or less that is sufficiently soft and has excellent workability. Example 1 Steel having the composition shown in Table 1 was melted in a converter, and test materials No. 1 to 14 were hot rolled to a plate thickness of 2.6 mm at a finishing temperature of 860 to 890°C and a coiling temperature of 520°C. After, plate thickness 0.32mm
Cold rolled to This cold-rolled sheet was held at a temperature of 710°C for 20 seconds to perform continuous annealing, then cooled to 400°C at a cooling rate of 50°C/sec, and held at 400°C for 30 seconds.
【表】
後常温まで冷却した。
その後、1.5％の調質圧延を施した後、錫めつ
きおよび溶錫処理を施した。結果は第２表に示す
とおりである。第２表より明らかなとおり供試鋼
No.１〜７の本発明鋼を使用する場合には、製品ぶ
りきは常に安定してＨR30Tが59以下の軟質のぶ
〓〓〓〓
りき板を得ることができるが、本発明の限定外の
組成の比較鋼No.８〜11では、いずれも調質度ＨR
30Tが60以上の硬質となることが示されている。
なお、第１表の比較鋼No.８〜11の成分中、アンダ
ーラインを施しているのは本発明の限定外成分で
ある。[Table] After cooling to room temperature. Thereafter, it was subjected to 1.5% temper rolling, followed by tin plating and hot tin treatment. The results are shown in Table 2. As is clear from Table 2, the test steel
When using Nos. 1 to 7 of the invention steel, the product tin is always stable and has a soft tint with an H R 30T of 59 or less.
However, comparative steel Nos. 8 to 11 with compositions outside the limits of the present invention all have a heat treatment degree of H R
It has been shown that 30T is harder than 60T.
In addition, among the components of comparative steel Nos. 8 to 11 in Table 1, the underlined components are components outside the scope of the present invention.
【表】
実施例 ２
第１表にて示した成分と同一供試材No.１〜No.11
を用いてより軟質材を得る目的で、熱延仕上温度
を760〜790℃と実施例１より低くして、その他の
条件を実施例１と同一として製造したぶりきにつ
いて調質度ＨR30Tを測定した結果は第３表に示
すとおりである。
第３表より明らかな如く、本発明鋼を使用する
場合には、ＨR30Tが52〜58のＴ―２１／２レベルのぶ
りきが得られることが判明した。しかし比較鋼は
この処理によつても本発明鋼よりはるかに硬質で
あることが分る。[Table] Example 2 Sample materials No. 1 to No. 11 with the same components as shown in Table 1
In order to obtain a softer material using the heat rolling process, the tinplate was produced with the hot rolling finishing temperature of 760 to 790°C, lower than that of Example 1, and with the other conditions being the same as in Example 1. The results of the measurements are shown in Table 3. As is clear from Table 3, it has been found that when the steel of the present invention is used, a T-21/2 level tinplate having an H R 30T of 52 to 58 can be obtained. However, it can be seen that the comparative steel is much harder than the invention steel even after this treatment.
【表】
第３表には更に比較のため過時効処理を行わな
かつた場合についても示した。過時効処理を行わ
なかつた場合には、いずれの供試鋼においても過
時効処理を行つたものに比し硬質であつて、熱延
条件のうち仕上温度の低い場合においても過時効
処理が必須要件であることを明示している。
上記実施例より明らかな如く、本発明はＣ、
solAl、Ｎの限定成分を有する連続鋳造鋼を使用
し、熱間圧延後の巻取温度を従来より低くして
550℃以下とし、かつ連続焼鈍条件を適当に規制
し、しかる後適正温度で過時効処理することによ
り、次の如き大なる効果を収めることができた。
(イ) 常に安定してJIS G3303にて規定するＨR30T
がＴ―３以下の軟質ぶりき板を製造することが
できる。
(ロ) 本発明法は熱延後の巻取温度を550℃以下と
低くしたので脱スケールが容易であり、酸洗ラ
インの通板速度を大とすることができるばかり
ではなく、熱延板中のカーバイドがフエライト
中に微細に析出するのでめつき板の耐食性を向
上させることができた。
(ハ) 本発明は軟質ぶりき板製造における最も好ま
しい製造方法、すなわち、連続鋳造鋼を使用す
る連続焼鈍法によつたので鋼板長手方向の材質
〓〓〓〓
が均一であるほか、従来法の箱焼鈍に比較すれ
ば格段の生産性の向上が可能となり、従つてコ
ストの大幅低減が可能となつた。
(ニ) 本発明法により得られた軟質ぶりきは加工性
にすぐれていることは勿論、鋼板形状および表
面性状も著しく良好である。
なお、本発明はぶりき板のみについて記載した
が、本発明法によるぶりき原板を用いてテインフ
リー鋼板を製造する場合には、ぶりき製造時の如
き溶錫化処理による硬度の上昇がないので、ぶり
きより更に一層の軟質テインフリー鋼板を得るこ
とができることは明らかである。[Table] Table 3 also shows the case where no overaging treatment was performed for comparison. If over-aging treatment was not performed, all of the sample steels were harder than those subjected to over-aging treatment, and over-aging treatment was required even under hot rolling conditions where the finishing temperature was low. It is clearly stated that it is a requirement. As is clear from the above examples, the present invention provides C,
Continuous casting steel with limited components of solAl and N is used, and the coiling temperature after hot rolling is lower than before.
By keeping the temperature at 550°C or lower, appropriately regulating the continuous annealing conditions, and then performing overaging treatment at an appropriate temperature, we were able to achieve the following great effects. (a) Always stable H R 30T specified by JIS G3303
It is possible to produce soft tin plate with a hardness of T-3 or less. (b) Since the method of the present invention lowers the coiling temperature after hot rolling to 550°C or less, descaling is easy, and not only can the pickling line speed be increased, but the hot rolled sheet Since the carbide inside was finely precipitated in the ferrite, the corrosion resistance of the plated plate could be improved. (c) Since the present invention is based on the most preferable manufacturing method for producing soft tin plate, that is, the continuous annealing method using continuous casting steel, the material quality in the longitudinal direction of the steel plate is
In addition to being uniform, productivity can be significantly improved compared to conventional box annealing, and costs can therefore be significantly reduced. (d) The soft tin plate obtained by the method of the present invention not only has excellent workability, but also has extremely good steel plate shape and surface quality. Note that although the present invention has been described only with respect to tin plate, when a stain-free steel plate is manufactured using a tin base plate according to the method of the present invention, there is no increase in hardness due to hot tin treatment as in the case of manufacturing tin plate. Therefore, it is clear that a softer, stain-free steel sheet can be obtained that is even softer than tinplate.
第１図は連続鋳造鋼においてＣ：0.02％を基準
とすsolAlおよびＮ量の最終ぶりき板の硬さに及
ぼす影響を示す相関図、第２図は連続鋳造鋼にお
いて、solAl：0.01％、Ｎ：0.003％を基準とする
場合のＣ含有量のぶりき板の硬さに及ぼす影響を
示す相関図であり、()は過時効処理の場合、
()は過時効処理不実施の場合である。第３図は
本発明鋼と比較鋼との熱延後の巻取温度差による
ぶりき板の硬さに及ぼす影響を示す相関図、第４
図は本発明による限定成分鋼の焼鈍温度差による
ぶりき板の硬さに及ぼす影響を示す相関図であ
る。
〓〓〓〓
Figure 1 is a correlation diagram showing the influence of solAl and N content on the hardness of the final tin plate in continuous casting steel, based on C: 0.02%, Figure 2 is a correlation diagram showing the influence of solAl: 0.01%, solAl: 0.01%, It is a correlation diagram showing the influence of C content on the hardness of tin plate when N: 0.003% is the standard, and () is in the case of over-aging treatment;
Cases in parentheses () are cases in which over-aging treatment is not implemented. Figure 3 is a correlation diagram showing the influence of the difference in coiling temperature after hot rolling between the invention steel and comparative steel on the hardness of tin plate;
The figure is a correlation diagram showing the influence of the annealing temperature difference on the hardness of a tin plate of limited component steel according to the present invention. 〓〓〓〓
Claims (1)
〜0.02％、Ｎ：0.004％以下を含む鋼を連続鋳造
にてスラブとする工程と、前記スラブを熱間圧延
後450℃以上550℃以下の温度で巻取つた後酸洗し
冷間圧延する工程と、前記冷延鋼帯を連続焼鈍炉
にて680℃以上A1変態点以下の温度に20秒以上保
持した後500℃以下の温度まで10〜500℃/secの冷
却速度で冷却する工程と、前記冷却した鋼帯を
350〜500℃の温度範囲に30秒以上保持した後冷却
する工程と、を有して成ることを特徴とする連続
焼鈍による軟質ぶりき板の製造方法。1 C: 0.01-0.03% by weight, solAl: 0.003
~0.02%, N: 0.004% or less into a slab by continuous casting, and the slab is hot-rolled and then coiled at a temperature of 450°C or more and 550°C or less, pickled, and cold rolled. and a step of holding the cold rolled steel strip in a continuous annealing furnace at a temperature of 680°C or more and below the A1 transformation point for 20 seconds or more, and then cooling it to a temperature of 500°C or less at a cooling rate of 10 to 500°C/sec. and the cooled steel strip.
A method for producing a soft tin plate by continuous annealing, comprising the steps of holding at a temperature in the range of 350 to 500°C for 30 seconds or more and then cooling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP141181A JPS57114618A (en) | 1981-01-08 | 1981-01-08 | Production of mild tin plate by continuous annealing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP141181A JPS57114618A (en) | 1981-01-08 | 1981-01-08 | Production of mild tin plate by continuous annealing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57114618A JPS57114618A (en) | 1982-07-16 |
| JPS6111290B2 true JPS6111290B2 (en) | 1986-04-02 |
Family
ID=11500737
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP141181A Granted JPS57114618A (en) | 1981-01-08 | 1981-01-08 | Production of mild tin plate by continuous annealing |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57114618A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5993826A (en) * | 1982-11-18 | 1984-05-30 | Nippon Kokan Kk <Nkk> | Manufacture of soft sheet for tinning |
| JPS59173222A (en) * | 1983-03-24 | 1984-10-01 | Nippon Steel Corp | Manufacture of soft surface treating stock sheet |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS50121118A (en) * | 1974-03-12 | 1975-09-22 |
-
1981
- 1981-01-08 JP JP141181A patent/JPS57114618A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS50121118A (en) * | 1974-03-12 | 1975-09-22 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57114618A (en) | 1982-07-16 |
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