JP2004009110A - Method of continuously casting magnesium alloy - Google Patents

Method of continuously casting magnesium alloy Download PDF

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Publication number
JP2004009110A
JP2004009110A JP2002167479A JP2002167479A JP2004009110A JP 2004009110 A JP2004009110 A JP 2004009110A JP 2002167479 A JP2002167479 A JP 2002167479A JP 2002167479 A JP2002167479 A JP 2002167479A JP 2004009110 A JP2004009110 A JP 2004009110A
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Japan
Prior art keywords
magnesium alloy
mold
cover
molten metal
continuous casting
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JP2002167479A
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Japanese (ja)
Inventor
Hideo Mizukami
水上 英夫
Toshihiko Murakami
村上 敏彦
Minoru Ishikawa
石川 稔
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Nippon Steel Corp
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Sumitomo Metal Industries Ltd
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Priority to JP2002167479A priority Critical patent/JP2004009110A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous casting method for obtaining a magnesium alloy cast slab of a high yield and high quality without using any protective gas or flux. <P>SOLUTION: In a method of continuously casting magnesium alloy where a molten metal is fed into a mold by using a dipping nozzle, a cover having a hole to pass the dipping nozzle through is arranged above the mold to cover the entire surface of the molten metal, and inert gas is fed into a space surrounded by the molten metal surface, the inner wall of the mold and the cover. <P>COPYRIGHT: (C)2004,JPO

Description

【0001】
【発明の属する技術分野】
本発明は、マグネシウム合金の連続鋳造方法に関し、さらに詳しくは、鋳型内の湯面から発生する合金成分蒸気の飛散、酸化物の生成ならびに溶湯への酸素および水素の吸収を抑制する連続鋳造方法に関する。
【0002】
【従来の技術】
溶融マグネシウム合金は気相と接触すると、その表面から主成分がマグネシウムである蒸気が発生する。この蒸気は大気と接触すると発火あるいは爆発の危険性を有する。また、溶融マグネシウム合金は大気に接触すると、大気中の酸素および水素を吸収して、製品の機械的特性を低下させる。これらを防止するためには、発生した蒸気の捕集、および溶融マグネシウム合金と大気との接触の遮断が必要である。
【0003】
したがって、マグネシウム合金を連続鋳造する場合においても、鋳型内のマグネシウム合金の溶湯が大気と接触する場合には、前述のように多量の蒸気が発生して発火あるいは爆発の危険性があり、安全な操業は困難である。また、溶融マグネシウム合金は、大気中の酸素との反応性が極めて高いことから、多量の酸化物が生成する。この酸化物は溶融マグネシウム合金よりも密度が大きいことから鋳型内の溶湯中を沈降し、凝固シェルに捕捉されて欠陥を形成しやすい。
【0004】
さらに、マグネシウム合金中の水素の溶解度は大きいため、大気中の水分と反応すると、容易に水素を吸収する。連続鋳造により製造された鋳片中の水素濃度が高くなると、圧延時に割れが発生するとともに、製品の成形性も著しく低下する。
【0005】
このような理由から、従来のマグネシウム合金の連続鋳造においては、比重の大きなSFガスやSFとCOとの混合ガスなどの保護ガス雰囲気下で鋳造を行うとともに、溶湯の酸化防止策として湯面上にフラックスを散布する方法がとられている。しかし、このような鋳造方法では、保護ガスの供給設備が新たに必要となる。
【0006】
また、SFガスは、地球温暖化の効果が極めて高いことから、環境対策上使用すべきではなく、さらに、SFガスは腐食性が強いことから、設備および建屋の防食対策も必要となる。もちろん、作業者の健康を害するという問題もある。しかも、マグネシウム合金は、その含有成分が蒸発しやすいことから、真空雰囲気下での連続鋳造は困難である。
また、マグネシウム合金の溶解では、大気との接触を絶つためにフラックスが用いられる場合がある。しかし、このフラックスの密度は、溶融マグネシウム合金の密度よりも大きいため、連続鋳造時の湯面の被覆用として用いると、フラックスが溶湯中を沈降し、凝固シェルに捕捉されて製品の欠陥を発生することとなる。このため、連続鋳造時にフラックスを用いて湯面を被覆することも困難である。
【0007】
【発明が解決しようとする課題】
本発明は、前述したマグネシウム合金の連続鋳造における問題点に鑑みてなされたものであり、その課題は、保護ガス雰囲気で鋳造する必要も、湯面をフラックスにより被覆する必要もなく、歩留りおよび品質に優れたマグネシウム合金鋳片および製品を得ることのできる連続鋳造方法を提供することにある。
【0008】
【課題を解決するための手段】
本発明者らは、上述の課題を解決するため、種々の条件におけるマグネシウム合金の連続鋳造試験結果に基づいて、歩留りおよび品質に優れた鋳片の製造方法につき検討を実施し、以下の知見を得た。
【0009】
(a)マグネシウム合金の連続鋳造時に、保護ガスやフラックスを用いずに、溶湯を大気に接触させると、マグネシウムを主成分とする蒸気が発生し、安全操業が不可能になるとともに、酸化物の生成、ならびにマグネシウム合金中の酸素および水素濃度の上昇を招く。
【0010】
(b)上記(a)の問題を解決し、製品の品質低下を防止するためには、鋳型内溶湯の湯面全体をカバーにより覆い、大気を遮断した状態で連続鋳造することが有効である。
【0011】
本発明は、上記の(a)および(b)の知見に基づいて完成されたものであり、その要旨は、下記のマグネシウム合金の連続鋳造方法にある。
【0012】
「浸漬ノズルを用いて鋳型内に溶湯を供給するマグネシウム合金の連続鋳造方法であって、浸漬ノズルを貫通させる孔を設けたカバーを鋳型上方に配置して溶湯表面の全体を覆うとともに、溶湯表面と鋳型内壁と前記カバーとで囲まれる空間部に不活性ガスを供給するマグネシウム合金の連続鋳造方法。」
本発明において、「マグネシウム合金」とは、マグネシウムの純金属、およびマグネシウムに合金元素が添加されたマグネシウム合金のいずれをも含む。
「浸漬ノズルを貫通させる孔を設けたカバー」とは、浸漬ノズルの貫通用の孔を有するカバーであって、前記孔は浸漬ノズルとの間のシール機構を有し、マグネシウム合金の蒸気の飛散を防止できる構造であることが望ましい。さらに、カバーと浸漬ノズルとが一体化したものであっても良い。
【0013】
「溶湯表面の全体を覆う」とは、カバーにより合金の溶湯表面全体をくまなく覆うことを意味し、カバーは鋳型上部において鋳型と密着する構造のもの、または鋳型と一体化した構造のものなどの何れでもよい。また、合金成分の蒸発を抑制するため、前記の空間部の雰囲気を加圧できる構造のものであっても良い。
【0014】
【発明の実施の形態】
本発明の内容についてさらに詳しく説明する。
【0015】
マグネシウムおよびマグネシウム合金の溶湯からはマグネシウム合金成分の蒸気が発生しやすい。これを抑制するためにフラックスを用いた場合にはフラックスの巻き込みによる製品品質の低下が著しいこと、保護ガスを用いた場合には環境悪化の問題があることなどから、前記合金溶湯の鋳造には本発明の連続鋳造方法が適している。
【0016】
本発明の連続鋳造方法は、前記のとおり、浸漬ノズルを貫通させる孔を設けたカバーを鋳型上方に配置して溶湯表面の全体を覆い、溶湯表面と鋳型内壁と前記カバーとで囲まれる空間に不活性ガスを供給することを特徴としている。
【0017】
図1は、鋳型上方にカバーを配置して湯面を覆う本発明に係る連続鋳造方法を示す模式図である。タンディッシュ1内のマグネシウム合金溶湯は、浸漬ノズル2を経由して連続鋳造鋳型3内に供給される。鋳型上方には、浸漬ノズルの貫通孔41を有するカバー4が配置されており、合金溶湯湯面の全体を覆って湯面と大気とを遮断している。湯面と鋳型内壁とカバーとで囲まれる空間部には不活性ガス供給口6から不活性ガス11が供給され、排ガス口7からは不活性ガスおよび合金成分の蒸気が排出され、ガス処理装置13を経由して排ガス12として系外に排出される。
【0018】
鋳型内の溶湯8は、鋳型内壁近傍から凝固して凝固シェル9を形成し、下方に引き抜かれて鋳片10を形成する。
【0019】
溶湯を覆うカバーは、マグネシウム合金およびその蒸気と反応しない材質のものが良く、例えばフェライト系ステンレス鋼製などが望ましい。浸漬ノズルの材料は、マグネシウム合金よりも融点が高く、かつ、マグネシウム合金と反応しない材質のものが良く、鋼製あるいはフェライト系ステンレス鋼製が望ましい。
【0020】
カバーに設けた浸漬ノズルの貫通孔への浸漬ノズルの貫通の方式は、O−リングなどのシール機構を介して蒸気の外部への飛散を防止し、かつ、相互の位置関係をスライドさせて変更できる形式のもの、あるいは、カバーと浸漬ノズルとを溶接などにより接合し一体化したものなど何れの形式のものであっても良い。
【0021】
カバーの鋳型への固定については、鋳型上部とカバー縁部との間にシール機構を有して密着する構造のもの、あるいは、鋳型上部とカバーとを溶接などにより接合し一体化したものなど何れの構造のものであっても良い。
また、溶湯表面と鋳型内壁とカバーとで囲まれる空間部に供給する不活性ガスとしては、Arガス、Heガスなどがあるが、合金品質の確保およびガス価格の面から、Arガスが望ましい。不活性ガスの供給量は、カバーの外部からの大気の侵入を防止できる程度の供給量で有ればよいが、合金溶湯表面1m当たり0.2〜10L(リットル)/minとするのが好ましい。
【0022】
また、不活性ガスおよび蒸気は、カバーに設けた排ガス口から前記空間部の外へ導き、ガス処理装置により処理後放散するか、またはマグネシウム分の回収を行うのが好ましい。
【0023】
マグネシウム合金溶湯からの合金成分の蒸発を抑制するために、溶湯表面と鋳型内壁とカバーとで囲まれる空間部の雰囲気をわずかに加圧しても良い。
【0024】
【実施例】
本発明のマグネシウム合金の連続鋳造方法の効果を確認するため、本発明例の試験および比較例の試験を行った。
〔本発明例〕
試験条件:
1)マグネシウム合金:Mg−3%Al−1%Zn(融点632℃)
2)注湯温度:750℃、
3)雰囲気 :大気雰囲気中、
4)鋳型材質:SUS304(内壁表面をアルミニウムコーティング)、
5)鋳型サイズ(内寸):幅700mm×厚み30mm×高さ200mm、
6)カバーの材質:SUS304(表面をアルミニウムコーティング)、
7)浸漬ノズルの材質:SUS304(表面をアルミニウムコーティング)、
8)浸漬ノズルのサイズ:外径20mm×肉厚2mm、
9)浸漬ノズルの加熱方法:シースヒーター加熱、
10)浸漬ノズルの加熱温度:750℃、
11)不活性ガス(Ar)供給量:1L/min、
12)鋳片引き抜き速度:0.5m/min、
13)鋳型オシレーション条件:振動数200cpm、ストローク3mm、サイン状波形。
【0025】
図1に示す方法により本発明の連続鋳造試験を行った。溶融マグネシウム合金をタンディッシュ1から浸漬ノズル2を介して連続鋳造鋳型3内へ供給した。鋳型上部には、カバー4が設置されており、溶湯の湯面全体を覆って、湯面から発生する蒸気の飛散を防止している。このカバーには不活性ガス供給用としてのAr供給口6、および排ガス口7が設けられている。溶湯湯面、鋳型内壁およびカバーにより囲まれる空間部には、不活性ガス供給配管を通してArガスが供給され、当該空間部を不活性ガス雰囲気に保持している。また、Arおよび合金成分の蒸気は、排ガス処理装置13により集塵などの処理を行って系外に排出される。
【0026】
本発明例の連続鋳造方法においては、後述する比較例の試験結果を基準とした鋳片中の酸素および水素の相対濃度は、ともに0.1であって、酸素および水素の吸収も発生せず、また、鋳片の表面に酸化層のない高品質の連続鋳造鋳片を製造することができた。なお、相対操業コストは0.1であり、良好であった。
〔比較例〕
試験条件:
1)マグネシウム合金:Mg−3%Al−1%Zn(融点632℃)
2)注湯温度:750℃、
3)雰囲気 :大気雰囲気中、
4)鋳型材質:SUS304(内壁表面をアルミニウムコーティング)、
5)鋳型サイズ(内寸):幅700mm×厚み30mm×高さ200mm、
6)カバーの使用:なし、
7)浸漬ノズルの材質:SUS304(表面をアルミニウムコーティング)、
8)浸漬ノズルのサイズ:外径20mm×肉厚2mm、
9)浸漬ノズルの加熱:なし、
10)保護用ガス:SF、供給量:5L/min、
11)鋳片引き抜き速度:0.5m/min、
12)鋳型オシレーション条件:振動数200cpm、ストローク3mm、サイン状波形。
【0027】
図2に示す方法により、比較例の連続鋳造試験を行った。鋳型内の湯面全体に保護用としてSFガスを供給して鋳造を行った。鋳型内の湯面近傍で発生する気体の熱対流により、保護ガスが湯面の全体を覆わなくなる場合が発生し、合金成分が大量に蒸発した。また、大気と接触して酸化物が生成し、これが連続鋳造鋳片の表面および表皮下に巻き込まれて欠陥となり、製品鋳片とはならなかった。また、前記酸化物が鋳型に付着して鋳片が拘束され、ブレークアウトが発生した。なお、部分的に引き抜かれた鋳片の分析を行ったところ、多量の酸素および水素が吸収されており、その含有量はともに、0.05質量%に達していた。
なお、前記のとおり、各発明例における鋳片中酸素濃度、鋳片中水素濃度、および相対操業コストは、比較例における各測定値およびブレークアウト回復処理作業などに要した費用を基準(1.0)として、算出した。
【0028】
【発明の効果】
本発明のマグネシウム合金の連続鋳造方法によれば、マグネシウム合金溶湯から発生する合金成分蒸気を飛散させることなく、マグネシウム合金溶湯中での酸化物の生成や酸素および水素の吸収を防止でき、表面品質および内部品質の優れたマグネシウム合金の連続鋳造鋳片を製造できる。
【図面の簡単な説明】
【図1】鋳型上方にカバーを配置して湯面を覆う本発明に係る連続鋳造方法を示す模式図である。
【図2】従来の連続鋳造方法を示す模式図である。
【符号の説明】
1:タンディッシュ、
2:浸漬ノズル、
3:連続鋳造鋳型、
4:カバー、
41:浸漬ノズル貫通孔、
5:加熱装置(シースヒーター)、
6:不活性ガス供給口、
7:排ガス口、
8:マグネシウム合金溶湯、
9:マグネシウム合金の凝固シェル、
10:マグネシウム合金鋳片、
11:不活性ガス、
12:排ガス、
13:排ガス処理装置
14:保護ガス。
[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a continuous casting method for a magnesium alloy, and more particularly to a continuous casting method for suppressing scattering of alloy component vapor generated from a molten metal surface in a mold, generation of an oxide, and absorption of oxygen and hydrogen into a molten metal. .
[0002]
[Prior art]
When the molten magnesium alloy comes into contact with the gas phase, vapor whose main component is magnesium is generated from the surface. This vapor has the danger of ignition or explosion on contact with the atmosphere. Further, when the molten magnesium alloy comes into contact with the atmosphere, it absorbs oxygen and hydrogen in the atmosphere, thereby deteriorating the mechanical properties of the product. In order to prevent these, it is necessary to collect generated steam and to block contact between the molten magnesium alloy and the atmosphere.
[0003]
Therefore, even when the magnesium alloy is continuously cast, when the molten magnesium alloy in the mold comes into contact with the atmosphere, a large amount of steam is generated as described above, and there is a risk of ignition or explosion, which is safe. Operation is difficult. In addition, the molten magnesium alloy has a very high reactivity with oxygen in the atmosphere, so that a large amount of oxide is generated. Since this oxide has a higher density than the molten magnesium alloy, it precipitates in the molten metal in the mold and is easily trapped by the solidified shell to form defects.
[0004]
Further, since the solubility of hydrogen in the magnesium alloy is large, the hydrogen easily absorbs when it reacts with moisture in the atmosphere. When the hydrogen concentration in the slab produced by continuous casting is high, cracks occur during rolling and the formability of the product is significantly reduced.
[0005]
For this reason, in the conventional continuous casting of magnesium alloy, casting is performed in a protective gas atmosphere such as SF 6 gas having a large specific gravity or a mixed gas of SF 6 and CO 2, and at the same time, as a measure for preventing oxidation of molten metal. A method of spraying a flux on a hot water surface has been adopted. However, such a casting method requires a new protective gas supply facility.
[0006]
Further, SF 6 gas, since it is very high effect of global warming, should not be used on environmental, further, since SF 6 gas is highly corrosive, is also required equipment and buildings corrosion protection . Of course, there is also the problem of harming the worker's health. In addition, continuous casting in a vacuum atmosphere is difficult because the components of the magnesium alloy are easily evaporated.
In dissolving a magnesium alloy, a flux may be used to cut off contact with the atmosphere. However, since the density of this flux is higher than the density of the molten magnesium alloy, when used for coating the molten metal surface during continuous casting, the flux sinks in the molten metal and is trapped by the solidified shell, causing defects in the product. Will be done. For this reason, it is also difficult to coat the molten metal surface with a flux during continuous casting.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problems in continuous casting of a magnesium alloy, and the problem is that there is no need to cast in a protective gas atmosphere, nor to coat the molten metal surface with flux, and to improve yield and quality. An object of the present invention is to provide a continuous casting method capable of obtaining a magnesium alloy slab and a product excellent in quality.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present inventors conducted a study on a method for manufacturing a slab excellent in yield and quality based on continuous casting test results of magnesium alloys under various conditions, and obtained the following findings. Obtained.
[0009]
(A) During continuous casting of a magnesium alloy, if the molten metal is brought into contact with the atmosphere without using a protective gas or flux, steam containing magnesium as a main component is generated, making safe operation impossible and reducing oxides. And increase the concentration of oxygen and hydrogen in the magnesium alloy.
[0010]
(B) In order to solve the above problem (a) and prevent the quality of the product from deteriorating, it is effective to cover the entire surface of the molten metal in the mold with a cover and perform continuous casting in a state where the atmosphere is shut off. .
[0011]
The present invention has been completed based on the above findings (a) and (b), and its gist lies in the following continuous casting method of a magnesium alloy.
[0012]
"This is a continuous casting method of a magnesium alloy for supplying a molten metal into a mold by using an immersion nozzle, wherein a cover provided with a hole for penetrating the immersion nozzle is arranged above the mold to cover the entire surface of the molten metal, And a method for continuously casting a magnesium alloy for supplying an inert gas to a space surrounded by the mold inner wall and the cover. "
In the present invention, the “magnesium alloy” includes both a pure metal of magnesium and a magnesium alloy in which an alloy element is added to magnesium.
"The cover provided with a hole for penetrating the immersion nozzle" is a cover having a hole for penetrating the immersion nozzle, wherein the hole has a seal mechanism between the immersion nozzle and the scatter of the magnesium alloy vapor. It is desirable to have a structure that can prevent this. Further, the cover and the immersion nozzle may be integrated.
[0013]
"To cover the entire surface of the molten metal" means to cover the entire surface of the molten metal of the alloy with a cover, and the cover has a structure that adheres to the mold at the top of the mold or a structure that is integrated with the mold. Any of Further, a structure that can pressurize the atmosphere in the space may be used in order to suppress evaporation of the alloy component.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
The contents of the present invention will be described in more detail.
[0015]
From the molten magnesium and magnesium alloy, the vapor of the magnesium alloy component is likely to be generated. When flux is used to suppress this, the product quality is significantly reduced due to the entrainment of the flux, and when a protective gas is used, there is a problem of environmental deterioration. The continuous casting method of the present invention is suitable.
[0016]
As described above, in the continuous casting method of the present invention, a cover provided with a hole for penetrating the immersion nozzle is disposed above the mold to cover the entire surface of the molten metal, and a space surrounded by the surface of the molten metal, the inner wall of the mold and the cover. It is characterized by supplying an inert gas.
[0017]
FIG. 1 is a schematic view showing a continuous casting method according to the present invention in which a cover is arranged above a mold to cover a molten metal surface. The molten magnesium alloy in the tundish 1 is supplied into the continuous casting mold 3 via the immersion nozzle 2. A cover 4 having a through hole 41 of an immersion nozzle is disposed above the mold, and covers the entire surface of the molten alloy so as to shut off the surface of the molten metal from the atmosphere. An inert gas 11 is supplied from an inert gas supply port 6 to a space surrounded by the molten metal surface, the mold inner wall, and the cover, and an inert gas and alloy component vapor are discharged from an exhaust gas port 7. Exhaust gas 12 is discharged out of the system via 13.
[0018]
The molten metal 8 in the mold solidifies from the vicinity of the inner wall of the mold to form a solidified shell 9 and is drawn downward to form a slab 10.
[0019]
The cover for covering the molten metal is preferably made of a material that does not react with the magnesium alloy and its vapor, and is desirably made of, for example, ferritic stainless steel. The material of the immersion nozzle is preferably a material having a higher melting point than the magnesium alloy and not reacting with the magnesium alloy, and is preferably made of steel or ferritic stainless steel.
[0020]
The method of penetrating the immersion nozzle into the through-hole of the immersion nozzle provided on the cover prevents the vapor from scattering to the outside through a sealing mechanism such as an O-ring, and changes the mutual positional relationship by sliding. Any type, such as a type that can be used or a type in which the cover and the immersion nozzle are joined and integrated by welding or the like, may be used.
[0021]
Regarding the fixation of the cover to the mold, there is a structure in which a seal mechanism is provided between the upper part of the mold and the edge of the cover to make a close contact, or a method in which the upper part of the mold and the cover are joined and integrated by welding or the like. It may have a structure of
As the inert gas supplied to the space surrounded by the surface of the molten metal, the inner wall of the mold and the cover, there are Ar gas, He gas and the like, but Ar gas is desirable from the viewpoint of securing alloy quality and gas price. The supply amount of the inert gas may be a supply amount that can prevent the invasion of the atmosphere from the outside of the cover, but is preferably 0.2 to 10 L (liter) / min per 1 m 2 of the surface of the molten alloy. preferable.
[0022]
In addition, it is preferable that the inert gas and the vapor are guided to the outside of the space from an exhaust gas port provided in the cover, and are then dissipated after being treated by a gas treatment device, or magnesium is preferably recovered.
[0023]
In order to suppress the evaporation of alloy components from the magnesium alloy melt, the atmosphere in the space surrounded by the surface of the melt, the inner wall of the mold, and the cover may be slightly pressurized.
[0024]
【Example】
In order to confirm the effect of the continuous casting method of the magnesium alloy of the present invention, a test of the present invention and a test of a comparative example were performed.
(Example of the present invention)
Test condition:
1) Magnesium alloy: Mg-3% Al-1% Zn (melting point 632 ° C)
2) Pouring temperature: 750 ° C,
3) Atmosphere: In air atmosphere,
4) Mold material: SUS304 (the inner wall surface is coated with aluminum),
5) Mold size (inner dimension): width 700 mm x thickness 30 mm x height 200 mm,
6) Cover material: SUS304 (the surface is coated with aluminum),
7) Material of immersion nozzle: SUS304 (the surface is coated with aluminum),
8) Size of immersion nozzle: outer diameter 20 mm x wall thickness 2 mm
9) Heating method of immersion nozzle: sheath heater heating,
10) Heating temperature of immersion nozzle: 750 ° C,
11) Inert gas (Ar) supply rate: 1 L / min,
12) Slab drawing speed: 0.5 m / min,
13) Mold oscillation conditions: frequency 200 cpm, stroke 3 mm, sinusoidal waveform.
[0025]
The continuous casting test of the present invention was performed by the method shown in FIG. The molten magnesium alloy was supplied from the tundish 1 through the immersion nozzle 2 into the continuous casting mold 3. A cover 4 is provided on the upper part of the mold to cover the entire surface of the molten metal and to prevent scattering of steam generated from the surface. The cover is provided with an Ar supply port 6 for supplying inert gas and an exhaust gas port 7. Ar gas is supplied to a space surrounded by the molten metal surface, the mold inner wall, and the cover through an inert gas supply pipe, and the space is maintained in an inert gas atmosphere. Further, the vapor of Ar and the alloy component is subjected to a treatment such as dust collection by an exhaust gas treatment device 13 and discharged out of the system.
[0026]
In the continuous casting method of the present invention, the relative concentrations of oxygen and hydrogen in the slab are both 0.1 based on the test results of the comparative examples described below, and neither absorption of oxygen nor hydrogen occurs. In addition, a high-quality continuous cast slab having no oxide layer on the surface of the slab could be produced. The relative operation cost was 0.1, which was favorable.
(Comparative example)
Test condition:
1) Magnesium alloy: Mg-3% Al-1% Zn (melting point 632 ° C)
2) Pouring temperature: 750 ° C,
3) Atmosphere: In air atmosphere,
4) Mold material: SUS304 (the inner wall surface is coated with aluminum),
5) Mold size (inner dimension): width 700 mm x thickness 30 mm x height 200 mm,
6) Use of cover: none,
7) Material of immersion nozzle: SUS304 (the surface is coated with aluminum),
8) Size of immersion nozzle: outer diameter 20 mm x wall thickness 2 mm
9) Heating of immersion nozzle: none,
10) Protective gas: SF 6 , supply amount: 5 L / min,
11) Slab drawing speed: 0.5 m / min,
12) Mold oscillation conditions: frequency 200 cpm, stroke 3 mm, sine waveform.
[0027]
The continuous casting test of the comparative example was performed by the method shown in FIG. Casting was performed by supplying SF 6 gas for protection to the entire surface of the molten metal in the mold. Due to the thermal convection of the gas generated near the molten metal surface in the mold, a case where the protective gas did not cover the entire molten metal surface occurred, and a large amount of the alloy component evaporated. In addition, oxides were generated in contact with the atmosphere, and were caught in the surface of the continuous cast slab and under the skin under the skin, resulting in defects, and did not become product slabs. In addition, the oxide adhered to the mold, restrained the slab, and caused breakout. The analysis of the partially drawn slab revealed that a large amount of oxygen and hydrogen had been absorbed, and the contents of both had reached 0.05% by mass.
As described above, the oxygen concentration in the slab, the hydrogen concentration in the slab, and the relative operating cost in each of the inventive examples are based on the measured values and the costs required for the breakout recovery process in the comparative example (1. 0).
[0028]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the continuous casting method of the magnesium alloy of the present invention, generation of oxides and absorption of oxygen and hydrogen in the magnesium alloy melt can be prevented without scattering alloy component vapor generated from the magnesium alloy melt, and surface quality can be prevented. And a continuous cast slab of magnesium alloy with excellent internal quality can be manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a continuous casting method according to the present invention in which a cover is arranged above a mold to cover a molten metal surface.
FIG. 2 is a schematic view showing a conventional continuous casting method.
[Explanation of symbols]
1: Tundish,
2: immersion nozzle
3: Continuous casting mold,
4: cover,
41: immersion nozzle through-hole,
5: heating device (sheath heater),
6: inert gas supply port,
7: exhaust gas outlet,
8: molten magnesium alloy,
9: solidified shell of magnesium alloy,
10: Magnesium alloy slab,
11: inert gas,
12: exhaust gas,
13: Exhaust gas treatment device 14: Protective gas.

Claims (1)

浸漬ノズルを用いて鋳型内に溶湯を供給するマグネシウム合金の連続鋳造方法であって、浸漬ノズルを貫通させる孔を設けたカバーを鋳型上方に配置して溶湯表面の全体を覆うとともに、溶湯表面と鋳型内壁と前記カバーとで囲まれる空間部に不活性ガスを供給することを特徴とするマグネシウム合金の連続鋳造方法。A continuous casting method of a magnesium alloy for supplying a molten metal into a mold using an immersion nozzle, wherein a cover provided with a hole for penetrating the immersion nozzle is disposed above the mold to cover the entire surface of the molten metal, A continuous casting method for a magnesium alloy, comprising supplying an inert gas to a space surrounded by a mold inner wall and the cover.
JP2002167479A 2002-06-07 2002-06-07 Method of continuously casting magnesium alloy Pending JP2004009110A (en)

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WO2006003899A1 (en) * 2004-06-30 2006-01-12 Sumitomo Electric Industries, Ltd. Method for producing magnesium alloy product
WO2006100858A1 (en) * 2005-03-24 2006-09-28 Sumitomo Electric Industries, Ltd. Casting nozzle
WO2006118157A1 (en) * 2005-04-27 2006-11-09 Central Glass Company, Limited Protective gas for metal production
WO2007063674A1 (en) * 2005-12-01 2007-06-07 Central Glass Company, Limited Protective gas composition for magnesium/magnesium alloy production and combustion preventing method
CN100434207C (en) * 2006-07-21 2008-11-19 江苏兴利来特钢有限公司 Continuous steel billet casting process and apparatus
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JP2010137255A (en) * 2008-12-11 2010-06-24 Kumamoto Univ Casting device and casting method, and method for manufacturing magnesium alloy billet
US9968994B2 (en) 2005-03-24 2018-05-15 Sumitomo Electric Industries, Ltd. Casting nozzle
CN108465790A (en) * 2018-04-03 2018-08-31 东北大学 It is used to prepare the continuous liquid supply device and application method of the long slab ingot of the big specification of magnesium alloy
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KR100985310B1 (en) * 2004-06-30 2010-10-04 스미토모덴키고교가부시키가이샤 Producing method for magnesium alloy material
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WO2006003899A1 (en) * 2004-06-30 2006-01-12 Sumitomo Electric Industries, Ltd. Method for producing magnesium alloy product
JP4678373B2 (en) * 2004-06-30 2011-04-27 住友電気工業株式会社 Method for producing magnesium alloy material
US7841380B2 (en) 2004-06-30 2010-11-30 Sumitomo Electric Industries, Ltd. Producing method for magnesium alloy material
JPWO2006003899A1 (en) * 2004-06-30 2008-04-17 住友電気工業株式会社 Method for producing magnesium alloy material
US9943904B2 (en) 2004-06-30 2018-04-17 Sumitomo Electric Industries, Ltd. Producing method for magnesium alloy material
WO2006100858A1 (en) * 2005-03-24 2006-09-28 Sumitomo Electric Industries, Ltd. Casting nozzle
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US9968994B2 (en) 2005-03-24 2018-05-15 Sumitomo Electric Industries, Ltd. Casting nozzle
US8863999B2 (en) 2005-03-24 2014-10-21 Sumitomo Electric Industries, Ltd. Casting nozzle
WO2006118157A1 (en) * 2005-04-27 2006-11-09 Central Glass Company, Limited Protective gas for metal production
US8016911B2 (en) 2005-04-27 2011-09-13 Central Glass Company, Limited Use of a protective gas composition for preventing oxidation or combustion of molten magnesium
WO2007063674A1 (en) * 2005-12-01 2007-06-07 Central Glass Company, Limited Protective gas composition for magnesium/magnesium alloy production and combustion preventing method
US7988762B2 (en) 2005-12-01 2011-08-02 Central Glass Company, Limited Protective gas composition for magnesium/magnesium alloy production and combustion preventing method
JP5068665B2 (en) * 2005-12-01 2012-11-07 セントラル硝子株式会社 Magnesium / magnesium alloy production protective gas composition and combustion prevention method
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JP2010137255A (en) * 2008-12-11 2010-06-24 Kumamoto Univ Casting device and casting method, and method for manufacturing magnesium alloy billet
WO2019132498A1 (en) * 2017-12-26 2019-07-04 주식회사 포스코 Highly corrosion-resistant magnesium alloy and manufacturing method therefor
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