JP4521879B2 - Continuous casting method of lead-containing steel - Google Patents
Continuous casting method of lead-containing steel Download PDFInfo
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- JP4521879B2 JP4521879B2 JP2006157886A JP2006157886A JP4521879B2 JP 4521879 B2 JP4521879 B2 JP 4521879B2 JP 2006157886 A JP2006157886 A JP 2006157886A JP 2006157886 A JP2006157886 A JP 2006157886A JP 4521879 B2 JP4521879 B2 JP 4521879B2
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- 229910000831 Steel Inorganic materials 0.000 title claims description 75
- 239000010959 steel Substances 0.000 title claims description 75
- 238000000034 method Methods 0.000 title claims description 20
- 238000009749 continuous casting Methods 0.000 title claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 229910000915 Free machining steel Inorganic materials 0.000 claims description 17
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 26
- 101100348084 Drosophila melanogaster CDase gene Proteins 0.000 description 9
- 239000000377 silicon dioxide Substances 0.000 description 9
- 239000004576 sand Substances 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 4
- 229910000423 chromium oxide Inorganic materials 0.000 description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009848 ladle injection Methods 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
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Description
この発明は、鉛快削鋼を連続鋳造にて製造する際に、モールド内で鋳片につかまって内蔵され、大型欠陥の要因となる、取鍋注入孔およびその周辺に沈降している鉛を取鍋からタンディッシュに注入することを防止する技術に関する。 In this invention, when lead free-cutting steel is produced by continuous casting, the lead settled in the ladle injection hole and its periphery, which is held by a slab in a mold and causes large-scale defects. The present invention relates to a technique for preventing pouring from a ladle into a tundish.
鋼の連続鋳造方法では、溶鋼を取鍋からタンディッシュに注入し、このタンディッシュから連続鋳造装置のモールドに溶鋼を鋳込んで連続鋳片を得る。この際タンディッシュには１台の取鍋の溶鋼が注入し終わると、次の取鍋から溶鋼を注入してタンディッシュには継続して注入する。 In the steel continuous casting method, molten steel is poured from a ladle into a tundish, and the molten steel is cast from the tundish into a mold of a continuous casting apparatus to obtain a continuous slab. At this time, when the molten steel of one ladle is completely poured into the tundish, molten steel is poured from the next ladle and continuously poured into the tundish.
この連続鋳造方法により鉛鋼を製造する場合、前回の取鍋から溶鋼をタンディッシュへの注入が終了し、次の取鍋から注入するとき、その注入初期に取鍋に沈降した溶鋼に未溶解の鉛が紛れ込みタンディッシュを通過して連続鋳造装置のモールド内に注入され鋳片にトラップされて重大な品質トラブルである大型の欠陥となることがある。 When producing lead steel by this continuous casting method, when molten steel is poured into the tundish from the previous ladle and then poured from the next ladle, it is not dissolved in the molten steel that has settled in the ladle at the beginning of the pouring. The lead of lead in may pass through the tundish and be injected into the mold of the continuous casting apparatus and trapped in the slab, resulting in a large defect that is a serious quality trouble.
ところで、溶鋼を取鍋からタンディッシュに注入する際に取鍋底のスライディングノズルを開口して注入するが、このスライディングノズルを開口する際に、ノズルの詰め物の珪砂あるいは珪砂とクロム酸化物あるいは小鉄屑の酸化物などの汚染源などがタンディッシュ中に落とし込まれ、さらに取鍋からの溶鋼流によって鋳造初期モールド中に混入されて非金属介在物の発生源となる。そこで、これらの珪砂あるいは珪砂やクロム酸化物や金属酸化物などの汚染源混入を阻止する方法を出願人は既に開発している（例えば、特許文献１参照。）。 By the way, when the molten steel is poured from the ladle into the tundish, the sliding nozzle at the bottom of the ladle is opened and poured, and when this sliding nozzle is opened, the silica padding or silica sand and chromium oxide or small iron scraps in the nozzle filling are filled. Contamination sources such as oxides are dropped into the tundish, and further mixed into the casting initial mold by the molten steel flow from the ladle to become a source of non-metallic inclusions. Therefore, the applicant has already developed a method for preventing contamination sources such as silica sand, silica sand, chromium oxide, and metal oxide from being mixed (see, for example, Patent Document 1).
さらにタンディッシュの底部および壁部に張設したアルミナ煉瓦上の表面層であるＭｇＯ系ボードの割れや剥離により、溶鋼中に混入する酸化物系介在物を低減し、溶鋼の清浄度を維持したまま連続鋳造する方法を同じく出願人は開発している（例えば、特許文献２参照。）。 Furthermore, the oxide inclusions mixed in the molten steel were reduced and the cleanliness of the molten steel was maintained by cracking and peeling of the MgO board, which is the surface layer on the alumina brick stretched on the bottom and wall of the tundish. The applicant has also developed a continuous casting method (see, for example, Patent Document 2).
しかし、上記の各特許文献に記載の方法の、取鍋やタンディッシュの壁材から生ずる珪砂あるいは珪砂とクロム酸化物や金属酸化物などを連続鋳造のモールド内に流入し鋳片に混入することをなくす方法では、鉛快削鋼の連続鋳造方法には適用できなかった。 However, in the method described in each of the above patent documents, silica sand generated from a ladle or tundish wall material or silica sand and chromium oxide or metal oxide is allowed to flow into a continuous casting mold and be mixed into the slab. This method cannot be applied to the lead free cutting steel continuous casting method.
鉛快削鋼の連続鋳造方法においては、溶製した溶鋼を取鍋からタンディッシュに注入する際に、取鍋内において溶鋼に未溶解で沈降する鉛がある場合がある。鉛は溶鋼に対して僅かな溶解度を有しているが、これが鋼塊の凝固冷却過程において金属鉛として析出するため、微細な直径約２μｍ程度の鉛粒が鋼中に微細に分布する。しかし、上記の溶解度を超える量の鉛は、鉛の比重が溶鋼よりも大きいため、主として取鍋の底に設けた注入孔およびその付近で溶鋼に未溶解で沈降して溶融鉛となっている。この溶鋼に未溶解で沈降した溶融鉛はタンディッシュに入り込むとモールドに移行して鋳片にトラップされ、得られた鋳片に重大な品質トラブルをもたらすこととなる。 In the continuous casting method of lead free-cutting steel, when molten steel is poured from a ladle into a tundish, there may be lead that settles undissolved in the molten steel in the ladle. Although lead has a slight solubility in molten steel, it precipitates as metallic lead in the solidification cooling process of the steel ingot, so that lead grains having a fine diameter of about 2 μm are finely distributed in the steel. However, the amount of lead exceeding the above-mentioned solubility is larger than that of molten steel, so it mainly settles undissolved in molten steel at the injection hole provided in the bottom of the ladle and in the vicinity thereof to become molten lead. . When the molten lead that has not yet dissolved in the molten steel enters the tundish, the molten lead moves to the mold and is trapped in the slab, resulting in serious quality troubles in the resulting slab.
そこで、本発明が解決しようとする課題は、これら鉛快削鋼の溶鋼に未溶解の沈降した溶融鉛を取鍋からタンディッシュへ溶鋼を注入する際に伴われて注入されないようにする方法を提供することである。 Therefore, the problem to be solved by the present invention is a method of preventing the molten molten lead that has not been dissolved in the molten steel of the lead free-cutting steel from being poured when the molten steel is poured from the ladle into the tundish. Is to provide.
上記の課題を解決するための本発明の手段は、鉛快削鋼の連続鋳造における方法であり、取鍋から溶鋼を溶鋼をタンディッシュに注入開始するに当たり、予めタンディッシュの湯落ち部以外の位置に捨湯鍋を保持し、溶鋼に未溶解で取鍋底部に沈降する溶融鉛を含有する取鍋底部の溶鋼を、上記の湯落ち部以外の位置に保持した捨湯鍋に、排出して捨湯し、次いで捨湯した取鍋をタンディシュの湯落ち部に移行し、この湯落ち部に、取鍋の捨湯した残りの溶鋼を注入することからなるタンディッシュ内の溶鋼に未溶解鉛の混入を防止する鉛快削鋼の連続鋳造方法におけるものである。 Means of the present invention for solving the above problems is a method in continuous casting of lead free-cutting steel , and in advance to start injecting molten steel from a ladle into the tundish, a portion other than the tundish pouring portion in advance. Hold the hot water ladle at the position, and discharge the molten steel at the bottom of the ladle containing molten lead that has not melted into the molten steel and settles to the bottom of the ladle into the hot water ladle held at a position other than the above-mentioned hot water dropping part and discard it. The ladle that has been boiled and then discarded is transferred to the tundish, where the undissolved lead is added to the molten steel in the tundish that consists of pouring the remaining molten steel from the ladle. This is a continuous casting method of lead free-cutting steel that prevents mixing.
すなわち、請求項１の発明では、取鍋から鉛快削鋼の溶鋼をタンディッシュに注入開始するに当たり、予めタンディッシュの湯落ち部位外の位置に捨湯鍋を保持し、溶鋼に未溶解で取鍋底部に沈降する溶融鉛を含有する取鍋底部の溶鋼を、上記の湯落ち部以外の位置に保持した捨湯鍋に排出して捨湯し、次いで捨湯した取鍋をタンディッシュの湯落ち部に移行し、該湯落ち部に取鍋の捨湯した残りの溶鋼をタンディッシュに注入する方法において、予め捨湯鍋に排出して捨湯する取鍋底部の溶鋼は、取鍋の溶鋼量１００トン当たり１００〜１０００ｋｇの溶鋼量とすることを特徴とするタンディッシュ内の溶鋼中への未溶解鉛の混入を防止する鉛快削鋼の連続鋳造方法である。 That is, according to the first aspect of the invention, in order to start pouring molten steel of lead free-cutting steel from the ladle into the tundish, the hot water ladle is held in advance at a position outside the tundish, and the undissolved steel is taken off. The molten steel at the bottom of the ladle containing molten lead that settles at the bottom of the pan is drained and drained into a ladle held at a position other than the above-mentioned ladle. In the method of injecting the remaining molten steel from the ladle into the tundish, the molten steel at the bottom of the ladle that is drained into the ladle beforehand and discarded is the amount of molten steel in the ladle. It is a continuous casting method of lead free-cutting steel that prevents undissolved lead from being mixed into molten steel in a tundish, characterized in that the amount of molten steel is 100 to 1000 kg per 100 tons.
上記の手段において捨湯する溶鋼量は、上記のとおり溶鋼量１００ｔ当たり１００〜１０００ｋｇとするが、この量は取鍋の状態、操業条件、鉛添加量により変化する。ところで０．１〜０．３質量％の鉛を含有する鉛快削鋼においては、溶鋼量１５０ｔの取鍋一基当たり、５００ｋｇの捨湯量とすることで、タンディッシュ内の溶鋼中への未溶解鉛の混入を防止することは達成できる。これらの捨湯量は当然に鍋の容量・形状により変わるものである。 The amount of molten steel discarded in the above means is 100 to 1000 kg per 100 ton of molten steel as described above, but this amount varies depending on the state of the ladle, operating conditions, and the amount of lead added. By the way, in the lead free-cutting steel containing 0.1 to 0.3% by mass of lead, the amount of hot water of 500 kg per ladle with a molten steel amount of 150 t can be reduced to the molten steel in the tundish. Preventing the inclusion of dissolved lead can be achieved. Naturally, the amount of hot water varies depending on the capacity and shape of the pan.
例えば、上記の特許文献１に記載の方法では、取鍋のスライディングノズルの詰め物である珪砂あるいは珪砂とクロム酸化物等がスライディングノズルのそのままの開口により、あるいは小鉄屑を詰めて酸素と可燃ガスにより加熱して強制開口することにより、スライディングノズル部で発生した珪砂や酸化鉄などが注入初期にタンディッシュに流れ込み不純物となる。そこで、この場合に予め捨湯するが、その捨湯量は取鍋のスライディングノズルの開口分のみであるので１００〜５００ｋｇと少なくてよい。
For example, in the method described in the above-mentioned
これに対し、鉛快削鋼の場合は、上記のように通常の予備カッティングの捨湯量では不十分であり取鍋の底部に沈降する溶融鉛を除去するためには１００〜１０００ｋｇの捨湯が必要で、このように沈降する溶融鉛をその周囲の溶鋼と共に排出し、溶鋼のみをタンディッシュに注入するものである。 On the other hand, in the case of lead free-cutting steel, the amount of normal preliminary cutting water is not sufficient as described above, and 100 to 1000 kg of hot water is required to remove the molten lead that settles at the bottom of the ladle. It is necessary to discharge the molten lead that settles in this way together with the surrounding molten steel, and only the molten steel is injected into the tundish.
本発明は、鉛快削鋼の連続鋳造において、取鍋の底部の溶鋼に溶解しないで沈降する溶融鉛を予め捨湯鍋に底部の溶鋼と共に排出することで、未溶融解鉛を含有しない鉛快速鋼の溶鋼だけをタンディッシュに注入することができ、得られた連続鋳片に未溶解鉛の混入による品質トラブルを防止することができ、信頼度の高い自動車などの機械部品が得られるなど、本発明は優れた効果を奏する。 In the continuous casting of lead free-cutting steel , the present invention discharges the molten lead that does not dissolve in the molten steel at the bottom of the ladle in advance together with the molten steel at the bottom to a hot water ladle so that it does not contain unmelted lead. Only molten steel of steel can be injected into the tundish, quality troubles due to mixing of undissolved lead into the obtained continuous cast slab can be prevented, and highly reliable machine parts such as automobiles can be obtained. The present invention has an excellent effect.
本発明を実施するための最良の形態を説明する。通常、鉛快削鋼は自動車用部品とする場合、自動車工業会では機械構造用鋼全般について０．１〜０．３％のＰｂを含有するものとし、Ｌ鋼と称すると規格に定めている。このような鉛快削鋼を連続鋳造する場合において、溶製した溶鋼を取鍋１からタンディッシュ４に注入開始するに当たり、図２および図３に示すスイングタワー３に取鍋１を載置する。スイングタワー３には取鍋１と反対側に次ヒートに注入する取鍋２を設置可能としている。スイングタワー３に取鍋１の下にはタンディッシュ４がある。予めタンディッシュ４の湯落ち部外であるタンディッシュ４の側部に捨湯鍋５が台車８に配設されている。
The best mode for carrying out the present invention will be described. In general, when lead free-cutting steel is used for automobile parts, the automobile industry association shall contain 0.1 to 0.3% of Pb for machine structural steel in general, and is defined in the standard as L steel. . In the case of continuously casting such lead free-cutting steel , the
スイングタワー３によりタンディッシュ４側に取鍋１が移されると、取鍋１のスライディングノズル６から樋７が捨湯鍋５に配置される。次いで、連続鋳造のため、図１に示すように、取鍋１からタンディッシュ４に溶鋼の注入を開始するに際し、タンディッシュ４の溶鋼１１中に未溶解でかつ取鍋１の底部に沈降している未溶解の溶融鉛を含有する溶鋼１２をタンディッシュ４の湯落ち部に入り込まないようにして樋７から取鍋１の底部の未溶解の溶融鉛を含有する溶鋼１２を沈降する未溶解の鉛と共に捨湯鍋５に受け入れる。この場合、図３に示すように、スライディングノズル６を開口する際にノズルの詰め物を先ず捨湯鍋５に落とし込む。取鍋１から初期の未溶解の溶融鉛を含有する溶鋼１２を捨湯鍋５に受け入れた後、スライディングノズル６を半開口とした状態で、取鍋１からの溶鋼１１の流れをタンディッシュ４に移し、その後スライディングノズル６を全開とし、溶鋼１１をタンディッシュ４に注入する。かくして、タンディッシュ４内の溶鋼１１に未溶解鉛の混入を防止しながら鉛含有鋼の溶鋼１１をタンディッシュ４から連続鋳造装置のモールドに注入して連続鋳造する。なお、図２で示す矢印１０は取鍋１を注入し終わるとスイングタワー３を回転して取鍋２と切り替えるためのスイングタワー３の回転方向を示すものである。
When the
上記の方法において、質量％で、Ｐｂ：０．２１％を含有する鉛快削鋼を溶製して溶鋼１１とし、この溶製した溶鋼１１を入れた１５０トンの取鍋１の底部に沈降する未溶解の鉛を含む溶鋼１２を予め捨湯鍋５に排出して捨湯する。この場合、取鍋１の底部に沈降する未溶解の鉛を含む溶鋼１２の捨湯する量を種々に変更して連続鋳造片を得て、上記の捨湯量を０ｋｇとして連続鋳造したものから得られた鋳片への未溶解の大きな鉛の混入割合を１００と指数で表わし、この指数に対比して、捨湯量を１００ｋｇ、２００ｋｇ、３００ｋｇ、５００ｋｇとしたときの未溶解の大きな鉛の混入割合の値をそれぞれ指数で表示して表１に示した。この表１から判るように、鋳片への未溶解の大きな鉛の混入する割合の指数は、捨湯量１００ｋｇで２、捨湯量２００ｋｇで０．５であり、捨湯量３００ｋｇのもので０、捨湯量５００ｋｇのもので０であった。
In the above method, lead free-cutting steel containing Pb: 0.21% in mass% is melted to form
ところで、鉛快削鋼は、上記したように自動車用の部品では０．１〜０．３％のＰｂを含有するので、この１５０トンの溶鋼を収容する取鍋１基当たりの捨湯量は１００〜１０００ｋｇの溶鋼とすることが望ましい。 By the way, as described above, lead free-cutting steel contains 0.1 to 0.3% of Pb in automobile parts, so the amount of hot water per ladle that accommodates 150 tons of molten steel is 100. It is desirable to use molten steel of ˜1000 kg.
１ 取鍋
２ 取鍋
３ スイングタワー
４ タンディッシュ
５ 捨湯鍋
６ スライディングノズル
７ 樋
８ 捨湯鍋台車
１０ 矢印
１１ 溶鋼
１２ 未溶解の溶融鉛を含有する溶鋼
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| JP2006157886A JP4521879B2 (en) | 2006-06-06 | 2006-06-06 | Continuous casting method of lead-containing steel |
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| JP4521879B2 true JP4521879B2 (en) | 2010-08-11 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61126954A (en) * | 1984-11-22 | 1986-06-14 | Nippon Steel Corp | Pouring method of molten metal in vessel |
| JPH08206795A (en) * | 1995-01-30 | 1996-08-13 | Daido Steel Co Ltd | Manufacture of pb steel |
| JP2003285143A (en) * | 2002-03-25 | 2003-10-07 | Sanyo Special Steel Co Ltd | Continuous casting method for pouring molten steel into tundish without mixing in contamination source |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61126954A (en) * | 1984-11-22 | 1986-06-14 | Nippon Steel Corp | Pouring method of molten metal in vessel |
| JPH08206795A (en) * | 1995-01-30 | 1996-08-13 | Daido Steel Co Ltd | Manufacture of pb steel |
| JP2003285143A (en) * | 2002-03-25 | 2003-10-07 | Sanyo Special Steel Co Ltd | Continuous casting method for pouring molten steel into tundish without mixing in contamination source |
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| JP2007326115A (en) | 2007-12-20 |
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