JP5636316B2 - Ingot manufacturing method - Google Patents
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- JP5636316B2 JP5636316B2 JP2011052439A JP2011052439A JP5636316B2 JP 5636316 B2 JP5636316 B2 JP 5636316B2 JP 2011052439 A JP2011052439 A JP 2011052439A JP 2011052439 A JP2011052439 A JP 2011052439A JP 5636316 B2 JP5636316 B2 JP 5636316B2
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- 238000004519 manufacturing process Methods 0.000 title claims description 34
- 238000002844 melting Methods 0.000 claims description 84
- 230000008018 melting Effects 0.000 claims description 84
- 239000002994 raw material Substances 0.000 claims description 81
- 229910052751 metal Inorganic materials 0.000 claims description 75
- 239000002184 metal Substances 0.000 claims description 75
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 54
- 229910052802 copper Inorganic materials 0.000 claims description 54
- 239000010949 copper Substances 0.000 claims description 54
- 230000006698 induction Effects 0.000 claims description 35
- 238000010438 heat treatment Methods 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 13
- 238000004090 dissolution Methods 0.000 claims description 4
- 239000000155 melt Substances 0.000 claims description 3
- 230000007547 defect Effects 0.000 description 48
- 238000000034 method Methods 0.000 description 36
- 239000000956 alloy Substances 0.000 description 28
- 229910045601 alloy Inorganic materials 0.000 description 25
- 239000010410 layer Substances 0.000 description 19
- 238000005266 casting Methods 0.000 description 13
- 238000007711 solidification Methods 0.000 description 9
- 230000008023 solidification Effects 0.000 description 9
- 239000010936 titanium Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229910052719 titanium Inorganic materials 0.000 description 5
- 229910010038 TiAl Inorganic materials 0.000 description 4
- 239000007769 metal material Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 229910001069 Ti alloy Inorganic materials 0.000 description 3
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- 230000003068 static effect Effects 0.000 description 3
- 239000002344 surface layer Substances 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 229910001093 Zr alloy Inorganic materials 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 206010053567 Coagulopathies Diseases 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- -1 Zircaloy Chemical class 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005275 alloying Methods 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
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000009852 coagulant defect Effects 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
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- Continuous Casting (AREA)
Description
本発明は、コールドクルーシブル誘導溶解（ＣＣＩＭ）法で、Ｔｉ、Ｚｒなどの活性金属を含有する合金、或いは、超高清浄度が要求されるＦｅ基合金、Ｎｉ基合金、Ｃｏ基合金などで成る大型で長尺の鋳塊を製造する鋳塊の製造方法に関するものである。 The present invention is an alloy containing an active metal such as Ti or Zr, or an Fe-based alloy, Ni-based alloy, Co-based alloy or the like that requires ultra-high cleanliness, by a cold crucible induction melting (CCIM) method. The present invention relates to an ingot manufacturing method for manufacturing a large and long ingot.
Ｔｉ合金、ジルカロイなどの活性金属を含有する合金や、超高清浄性が要求されるＦｅ基合金、Ｎｉ基合金、Ｃｏ基合金等で成る鋳塊は、現在、工業的には、真空アーク溶解法、プラズマアーク溶解法、電子ビーム溶解法、エレクトロスラグ溶解法などによって製造されている。これらの溶解法は、いずれも水冷された銅材をるつぼ溶解容器として用いる溶解法である。これらの溶解法は、合金原料の全量を一括して溶解せずに、少量ずつ供給して溶解を行い、形成される溶融金属浴を下側から順次凝固させて鋳塊を製造することを特徴としており、現在、１〜１０ｔｏｎ程度の鋳塊がこれらの溶解法を用いて製造されている。但し、これらの溶解方法は、溶湯の攪拌力が小さく、合金成分の不均一が起こりやすいという課題も併せ持っている。 Ingots made of Ti alloys, alloys containing active metals such as Zircaloy, and Fe-based alloys, Ni-based alloys, and Co-based alloys that require ultra-high cleanliness are currently industrially vacuum arc melting. The plasma arc melting method, the electron beam melting method, the electroslag melting method, etc. are used. These melting methods are all melting methods using a water-cooled copper material as a crucible melting container. These melting methods are characterized in that the entire amount of alloy raw material is not melted all at once, but is supplied and dissolved little by little, and the formed molten metal bath is solidified sequentially from the lower side to produce an ingot. Currently, ingots of about 1 to 10 tons are manufactured using these melting methods. However, these melting methods also have the problem that the stirring power of the molten metal is small and the alloy components are likely to be uneven.
これに対し、コールドクルーシブル誘導溶解（ＣＣＩＭ）法は、合金原料を一括で全量溶解して合金化した後に、凝固させて鋳塊を製造する方法である。この溶解方法であれば、合金化が容易であり、合金成分の不均一を発生することなく均質な鋳塊を製造することができるが、このＣＣＩＭ法によって大型の鋳塊を製造する技術自体は、現状ではまだ開発途上の段階である。 On the other hand, the cold crucible induction melting (CCIM) method is a method in which an alloy raw material is melted in a batch to form an alloy and then solidified to produce an ingot. With this melting method, alloying is easy and a homogeneous ingot can be produced without causing non-uniformity of alloy components. However, the technology itself for producing a large ingot by this CCIM method is Currently, it is still in the development stage.
従来からＣＣＩＭ法により比較的大型で長尺の鋳塊を製造する方法として、非特許文献１に記載の製造方法が知られている。この製造方法は、水冷銅るつぼを用いて、その外周部に設置した高周波コイルに高周波電流を通電して、水冷銅るつぼ内に供給した合金原料を誘導溶解し、次いで、水冷銅るつぼの底部を下方に引き抜くことで、大型で長尺の鋳塊を製造する方法である。この製造方法は、水冷銅るつぼと溶湯プールの間にフッ化カルシウム(ＣａＦ２)などのフッ化物系スラグを、精錬効果、電気的絶縁効果、或いは引き抜き時の潤滑効果などを狙って添加することを特徴としている。この方法により、溶解原料としてスポンジＴｉを用いて、直径５インチの長尺鋳塊が製造できることが示されているが、Ｔｉ溶湯に溶融フッ化カルシウム(ＣａＦ２)が接触することとなるため、鋳塊中にフッ素（Ｆ）が数十ｐｐｍほど混入する結果となっており、高清浄な鋳塊を製造するには問題がある。 Conventionally, a manufacturing method described in Non-Patent Document 1 is known as a method for manufacturing a relatively large and long ingot by the CCIM method. In this manufacturing method, using a water-cooled copper crucible, a high-frequency current is passed through a high-frequency coil installed on the outer periphery thereof to inductively dissolve the alloy raw material supplied into the water-cooled copper crucible, and then the bottom of the water-cooled copper crucible is removed. This is a method for producing a large and long ingot by pulling downward. In this manufacturing method, fluoride-based slag such as calcium fluoride (CaF 2 ) is added between the water-cooled copper crucible and the molten metal pool for the purpose of refining effect, electrical insulation effect, or lubrication effect during drawing. It is characterized by. By this method, it is shown that a long ingot having a diameter of 5 inches can be produced using sponge Ti as a melting raw material, but since molten calcium fluoride (CaF 2 ) comes into contact with the molten Ti, As a result, about several tens of ppm of fluorine (F) is mixed in the ingot, and there is a problem in producing a highly clean ingot.
また、ＣＣＩＭ法によって大型で長尺の鋳塊を製造する方法として、フッ化カルシウム(ＣａＦ２)などの精錬材を添加せずに、コイルからの電磁気力により溶融金属浴を保持して、水冷銅るつぼの底部を引き抜くことにより、長尺鋳塊を製造する方法も考えることはできる。しかしながら、たとえこの製造方法で長尺鋳塊を製造したとしても、不適切な操業条件を用いると、鋳塊内部に溶け残り原料が残留したり、鋳塊表面に大きな表面欠陥が発生したりして、歩留まりが大幅に悪化するなどの問題が発生し、健全な鋳塊を製造することは困難である。 In addition, as a method for producing a large and long ingot by the CCIM method, a molten metal bath is held by electromagnetic force from a coil without adding a refining material such as calcium fluoride (CaF 2 ), and water cooling A method of producing a long ingot by pulling out the bottom of the copper crucible can also be considered. However, even if a long ingot is manufactured by this manufacturing method, if inappropriate operating conditions are used, undissolved raw materials may remain inside the ingot or a large surface defect may occur on the ingot surface. Thus, problems such as a significant deterioration in yield occur, and it is difficult to produce a sound ingot.
発明者らは、ＣＣＩＭ法で塊状の合金原料を供給しつつ、水冷銅製るつぼのるつぼ底を下方に引き抜くことで、溶解鋳造の操業条件を最適化することにより、合金原料などの溶け残りのない健全な大型の鋳塊を製造する方法について特許出願している(特許文献１，２)。しかしながら、これらの製造方法においても、少しでも不適切な操業条件を用いると、鋳塊の表面に著しく大きな凹凸が形成されてしまうという課題が残されていた。 The inventors of the present invention do not leave unmelted alloy raw materials or the like by optimizing the operating conditions of the melt casting by pulling the crucible bottom of the water-cooled copper crucible downward while supplying the bulk alloy raw materials by the CCIM method. A patent application has been filed for a method for producing a healthy large ingot (Patent Documents 1 and 2). However, even in these manufacturing methods, there is a problem that extremely large irregularities are formed on the surface of the ingot when a slightly inappropriate operating condition is used.
更に、発明者らは、この課題を解決するために、高周波コイルのコイル電圧を一定値に保持した状態で、上方より供給する前記溶解原料の供給速度の制御、および／または、下方に引き抜く際の鋳塊の引抜速度の制御を行うことで、溶解原料を溶解して溶湯プールとする際に投入する電力値の変動幅を、所定の電力値の±５％の範囲として鋳塊を製造する方法を、特許文献３として提案している。この製造方法を採用して実際に大型で長尺の鋳塊を実験的に製造したところ、確かに鋳塊に鋳造欠陥が発生することは、殆どは抑制することはできたが、初期操業時に鋳塊の表面に形成されるくびれ状欠陥については、抑制することが難しいことを確認した。 Furthermore, in order to solve this problem, the inventors have controlled the supply rate of the melting raw material supplied from above and / or withdraw it downward while keeping the coil voltage of the high frequency coil at a constant value. By controlling the drawing speed of the ingot, the ingot is manufactured with the fluctuation range of the power value input when melting the molten raw material being used as the molten metal pool within a range of ± 5% of the predetermined power value. A method is proposed as Patent Document 3. When this manufacturing method was used to experimentally manufacture a large and long ingot, the occurrence of casting defects in the ingot was almost completely suppressed. It was confirmed that it was difficult to suppress the constricted defects formed on the surface of the ingot.
本発明は、上記従来の問題を解消せんとしてなされたもので、初期操業時に鋳塊の表面に形成されるくびれ状欠陥の発生を抑制することができ、健全な大型の鋳塊を安定して製造することができる鋳塊の製造方法を提供することを課題とするものである。 The present invention has been made as a solution to the above-mentioned conventional problems, and can suppress the occurrence of constricted defects formed on the surface of the ingot during initial operation, and can stably produce a healthy large ingot. An object of the present invention is to provide a method for producing an ingot that can be produced.
請求項１記載の発明は、るつぼ底が上下方向に移動自在に形成された水冷銅製るつぼの内部に供給した初装原料を、その水冷銅製るつぼの周囲を取り巻く高周波コイルによる誘導加熱で溶解して溶湯プールとし、前記るつぼ底を下方に移動させることによりるつぼ底上の前記溶湯プールを、前記高周波コイルによる誘導加熱領域外に引き抜いて下方より凝固させて、前記溶湯プールを所定の容量とした後、前記水冷銅製るつぼの内部に上方より棒状溶解原料で成る追加装入原料を供給して、前記高周波コイルによる誘導加熱で前記棒状溶解原料で成る追加装入原料を下端から溶解しつつ、前記るつぼ底を下方に移動させて、前記溶湯プールを前記誘導加熱領域外に引き抜くことにより、前記溶湯プールを所定の容量を保たせた状態のまま、下方より凝固させて、長尺の鋳塊を製造する鋳塊の製造方法であって、前記棒状溶解原料で成る追加装入原料の下端を前記溶湯プールに浸漬させる直前の溶解電力を、前記棒状溶解原料で成る追加装入原料の下端を前記溶湯プールに浸漬させた後の定常時の溶解電力を１００％とした場合８５％以上９５％未満の範囲の電力値として鋳塊を製造することを特徴とする鋳塊の製造方法である。 According to the first aspect of the present invention, the raw material supplied to the inside of the water-cooled copper crucible having the crucible bottom movable in the vertical direction is melted by induction heating with a high-frequency coil surrounding the water-cooled copper crucible. After making the molten metal pool and moving the crucible bottom downward, the molten metal pool on the bottom of the crucible is pulled out of the induction heating area by the high frequency coil and solidified from below to make the molten metal pool a predetermined capacity. The crucible is supplied to the inside of the water-cooled copper crucible from above with the additional charging material consisting of the rod-shaped melting raw material being melted from the lower end by induction heating by the high-frequency coil. The bottom is moved downward, and the molten pool is pulled out of the induction heating region, so that the molten pool is kept in a state where a predetermined capacity is maintained. By more coagulation, a process for the preparation of the ingot for manufacturing an ingot of long, the dissolution power immediately before immersing the lower end of the additional charging material consisting of the rod-shaped raw material for melting in the melt pool, the bar dissolution The ingot is manufactured with a power value in the range of 85% or more and less than 95% when the melting power in the steady state after the lower end of the additional charging raw material made of the raw material is immersed in the molten metal pool is 100%. It is a manufacturing method of the ingot which makes it.
本発明の鋳塊の製造方法によると、初期操業時に鋳塊の表面に形成されるくびれ状欠陥の発生を抑制することができ、健全な大型の鋳塊を安定して製造することができる。 According to the method for producing an ingot of the present invention, it is possible to suppress the occurrence of constricted defects formed on the surface of the ingot during initial operation, and it is possible to stably produce a healthy large ingot.
以下、本発明を添付図面に示す実施形態に基づいて更に詳細に説明する。 Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
本発明の鋳塊の製造方法によって製造される鋳塊は、図１及び図２に示すような、るつぼ底１が上下方向に移動自在に形成された水冷銅製るつぼ２と、その水冷銅製るつぼ２の周囲を取り巻くように配置された高周波コイル４で成るコールドクルーシブル誘導溶解（ＣＣＩＭ）装置Ａを用いて製造することができる。 The ingot manufactured by the method for manufacturing an ingot of the present invention includes a water-cooled copper crucible 2 in which a crucible bottom 1 is formed so as to be movable in the vertical direction as shown in FIGS. 1 and 2, and the water-cooled copper crucible 2. Can be produced using a cold crucible induction melting (CCIM) apparatus A comprising a high-frequency coil 4 arranged so as to surround the periphery thereof.
このコールドクルーシブル誘導溶解装置Ａを構成する水冷銅製るつぼ２は、複数本の中空軸状の銅製セグメント７を円筒状に組み合わせて構成されており、底部には円形で銅製のるつぼ底１が配置されている。複数本の銅製セグメント７、７、…の間には、０．０５〜２ｍｍのスリット１３が設けられており、それらスリット１３には、電気的絶縁のため、イットリア（Ｙ２Ｏ３）系セメント、或いはアルミナ（Ａｌ２Ｏ３）系セメント等の絶縁材が埋め込まれている。高周波コイル４は、水冷銅製るつぼ２の周囲をその上下端をある程度残し、螺旋状に取り巻くように水冷銅製るつぼ２の表面より僅かに離れて設けられており、大出力の高周波電源８に接続されている。銅製セグメント７、るつぼ底１、高周波コイル４は夫々中空状であり、中空内部には冷却水が注入されている。るつぼ底１は、下方のシリンダ等の引き抜き機構９に連結されて上下方向に移動自在に構成されており、水冷銅製るつぼ２の銅製セグメント７で成る円筒状の本体から下方に引き出すように移動させることができる。 The water-cooled copper crucible 2 constituting the cold crucible induction melting apparatus A is formed by combining a plurality of hollow shaft copper segments 7 in a cylindrical shape, and a circular copper crucible bottom 1 is disposed at the bottom. ing. Between the plurality of copper segments 7, 7,..., 0.05 to 2 mm slits 13 are provided, and these slits 13 are provided with yttria (Y 2 O 3 ) cement for electrical insulation. Alternatively, an insulating material such as alumina (Al 2 O 3 ) cement is embedded. The high-frequency coil 4 is provided slightly apart from the surface of the water-cooled copper crucible 2 so that it surrounds the water-cooled copper crucible 2 around the water-cooled copper crucible 2 while leaving the upper and lower ends to some extent, and is connected to a high-power high-frequency power source 8. ing. The copper segment 7, the crucible bottom 1, and the high frequency coil 4 are each hollow, and cooling water is injected into the hollow interior. The crucible bottom 1 is connected to a drawing mechanism 9 such as a lower cylinder and is configured to be movable in the vertical direction. The crucible bottom 1 is moved so as to be drawn downward from the cylindrical main body formed of the copper segment 7 of the water-cooled copper crucible 2. be able to.
このコールドクルーシブル誘導溶解装置Ａを用いて、Ｔｉ、Ｔｉ合金、ＴｉＡｌ基合金、Ｚｒ、Ｚｒ合金、Ｆｅ基合金、Ｎｉ基合金、Ｃｏ基合金などで成る鋳塊６の製造が行われるが、このコールドクルーシブル誘導溶解装置Ａは、真空チャンバーＢ内に設けられている。また、るつぼ底１の上面には、溶解開始時のスタート材となる底盤１０が取り付けられている。この底盤１０は、純チタン材やチタン合金材、炭素鋼、ステンレス鋼等、製造される鋳塊６の材質を考慮した金属材料で形成されている。 An ingot 6 made of Ti, Ti alloy, TiAl base alloy, Zr, Zr alloy, Fe base alloy, Ni base alloy, Co base alloy or the like is manufactured using this cold crucible induction melting apparatus A. The cold crucible induction melting apparatus A is provided in the vacuum chamber B. Further, a bottom plate 10 serving as a starting material at the start of melting is attached to the upper surface of the crucible bottom 1. The bottom plate 10 is formed of a metal material that takes into account the material of the ingot 6 to be manufactured, such as pure titanium material, titanium alloy material, carbon steel, and stainless steel.
尚、本発明が対象とする大型の鋳塊６については、特にその大きさを限定しないが、例えば、その寸法は、直径２００ｍｍ以上、その直径に対する高さ寸法が１．５倍以上、即ち３００ｍｍ以上とすることが好ましい。前記した寸法に達しない小型の鋳塊６であれば、特にコールドクルーシブル誘導溶解装置Ａを用いなくても比較的容易に製造することができると共に、比重の重い金属材料で製造した鋳塊６であっても５０ｋｇ以下の小型であって、特に実用性もないからである。また、鋳塊６の直径は１０００ｍｍ以下、直径に対する高さ寸法の倍率は５倍以下とすることが好ましい。 Incidentally, the size of the large ingot 6 targeted by the present invention is not particularly limited. For example, the size is 200 mm or more in diameter, and the height dimension with respect to the diameter is 1.5 times or more, that is, 300 mm. The above is preferable. If it is the small ingot 6 which does not reach the above-mentioned size, it can be manufactured relatively easily without using the cold crucible induction melting apparatus A, and the ingot 6 made of a metal material having a heavy specific gravity. Even if it is, it is 50 kg or less and is not particularly practical. The diameter of the ingot 6 is preferably 1000 mm or less, and the magnification of the height dimension with respect to the diameter is preferably 5 times or less.
次に、前記したコールドクルーシブル誘導溶解装置Ａを用い、るつぼ底１を下方に移動させることにより大型の鋳塊６を製造する方法について説明する。 Next, a method for manufacturing a large ingot 6 by moving the crucible bottom 1 downward using the cold-crucible induction melting apparatus A will be described.
コールドクルーシブル誘導溶解装置Ａ等を用いて鋳塊６を製造する作業を始める前に、まず溶解原料３を準備する。溶解原料３には、水冷銅製るつぼ２の内部に操業初期に供給される塊状等の初装原料３ａと、その初装原料３ａの溶解が完了した後、水冷銅製るつぼ２内に供給する複数本の棒状溶解原料等で成る追加装入原料３ｂがある。 Before starting the operation of manufacturing the ingot 6 using the cold crucible induction melting apparatus A or the like, the melting raw material 3 is first prepared. The melted raw material 3 includes, in the water-cooled copper crucible 2, a bulky initial raw material 3 a that is supplied at the initial stage of operation, and a plurality of pieces that are supplied into the water-cooled copper crucible 2 after the initial raw material 3 a is completely dissolved. There is an additional charging raw material 3b made of a rod-shaped melting raw material.
まず、溶解開始時のスタート材となる底盤１０を上面に取り付けたるつぼ底１を所定の高さ位置に配置した状態で、水冷銅製るつぼ２の内部に、初装原料３ａを供給する。この状態で、高周波コイル４に高周波電流を通電することにより、高周波コイル４による誘導加熱領域にある底盤１０の上部と初装原料３ａを同時に溶解する。溶解された底盤１０の上部と初装原料３ａは、図２に示すように、初期の溶湯プール５を形成する。 First, the raw material 3a is supplied to the inside of the water-cooled copper crucible 2 in a state where the crucible bottom 1 with the bottom 10 serving as a starting material at the start of melting is disposed at a predetermined height position. In this state, by applying a high-frequency current to the high-frequency coil 4, the upper part of the bottom plate 10 and the initial raw material 3 a in the induction heating region by the high-frequency coil 4 are dissolved simultaneously. As shown in FIG. 2, the melted upper part of the bottom base 10 and the initial raw material 3 a form an initial molten metal pool 5.
溶解完了後に、るつぼ底１を下方に移動させることにより、るつぼ底１上の溶湯プール５を、高周波コイル４による誘導加熱領域外に引き抜いて下方より冷却凝固させ、初期の鋳塊６を形成する。尚、その鋳塊６の上方に残す溶湯プール５の容量は、次工程で追加装入原料３ｂを供給する際に溶湯プール５を連続して誘導加熱領域外に引き抜くのに適した所定の容量とする。 After the completion of melting, the crucible bottom 1 is moved downward, whereby the molten metal pool 5 on the crucible bottom 1 is drawn out of the induction heating region by the high frequency coil 4 and cooled and solidified from below to form the initial ingot 6. . In addition, the capacity | capacitance of the molten metal pool 5 left above the ingot 6 is a predetermined capacity | capacitance suitable for drawing out the molten metal pool 5 continuously out of an induction heating area | region when supplying the additional charging raw material 3b at the next process. And
次に、るつぼ底１を徐々に下方に引き下げれば、るつぼ底１上の溶湯プール５は、高周波コイル４による誘導加熱領域から徐々に下方に引き抜かれることとなり、その下方から冷却されて凝固を開始する。尚、溶湯プール５のうち水冷銅製るつぼ２の内壁面に接触した外表面から、水冷により事前に凝固を開始して凝固層１２となっているため、溶湯プール５は下方に引き抜いても流れ出すことはない。 Next, if the crucible bottom 1 is gradually lowered downward, the molten metal pool 5 on the crucible bottom 1 is gradually drawn downward from the induction heating region by the high frequency coil 4 and is cooled from below to solidify. Start. In addition, since the solidification layer 12 is started in advance by water cooling from the outer surface in contact with the inner wall surface of the water-cooled copper crucible 2 in the molten metal pool 5, the molten metal pool 5 flows out even if it is pulled downward. There is no.
尚、単に溶湯プール５を下方の誘導加熱領域外に引き抜くだけであると、水冷銅製るつぼ２内の溶湯プール５の容量は徐々に減少するため、その引き抜き量と見合う容量の追加装入原料３ｂを上方より徐々に追加供給して、その下端から順次溶解する。この追加装入原料３ｂの追加供給により、溶湯プール５の容量を常に一定に保つことができる。この引き抜きによって凝固した部位が長尺の鋳塊６となる。尚、上方より供給する追加装入原料３ｂは、例えば、複数本の棒状溶解原料を束にして、真空チャンバーＢの上部に設けた吊り下げ機構１１に吊り下げた状態で、その下端側から溶湯プール５の減少量に見合った量だけ徐々に供給される。 If the molten pool 5 is simply pulled out of the induction heating area below, the capacity of the molten pool 5 in the water-cooled copper crucible 2 gradually decreases, so that the additional charged raw material 3b having a capacity commensurate with the extracted amount. Are gradually added from above and dissolved in order from the lower end. By the additional supply of the additional charging raw material 3b, the capacity of the molten metal pool 5 can be always kept constant. The portion solidified by this drawing becomes a long ingot 6. The additional charging raw material 3b supplied from above is, for example, a molten metal from the lower end side in a state where a plurality of rod-shaped melting raw materials are bundled and hung on a hanging mechanism 11 provided at the upper part of the vacuum chamber B. An amount corresponding to the amount of decrease in the pool 5 is gradually supplied.
この引き抜き鋳造法によって製造される鋳塊６には、一般に行われている重力鋳造法で製造する鋳塊６のように中心部に引け巣欠陥が発生することはなく、健全な鋳塊６となる。特に、ＴｉＡｌ基合金のように割れやすい合金材料の鋳塊の製造方法としては、引け巣欠陥を起因とする割れが発生しないので、この引き抜き鋳造法は適したものということができる。 The ingot 6 manufactured by the pull-out casting method does not have a shrinkage defect in the central portion unlike the ingot 6 manufactured by the generally performed gravity casting method. Become. In particular, as a method for producing an ingot of an alloy material that is easily cracked, such as a TiAl-based alloy, cracks due to shrinkage defects do not occur, and therefore this drawing casting method can be said to be suitable.
しかしながら、単に以上の製造方法で、大型で長尺の鋳塊６を製造した場合、製造条件によれば、鋳塊６の表面に、図３に示すような、深さが２０ｍｍ以上に及ぶくびれ状欠陥ａや、その深いくびれ状欠陥ａに溶湯が流入して二重の凝固組織となった二重肌欠陥ｂといった表面欠陥が生成される可能性がある。このような深いくびれ状欠陥ａや二重肌欠陥ｂのような表面欠陥が鋳塊６の表面に生成されてしまうと、鋳塊６の表面の切削（皮削り）が必要となり、鋳塊６の歩留まりが著しく低下してしまい、条件によれば、使用が不可能なものとなってしまう。 However, when a large and long ingot 6 is manufactured simply by the above manufacturing method, according to the manufacturing conditions, a constriction with a depth of 20 mm or more is formed on the surface of the ingot 6 as shown in FIG. There is a possibility that a surface defect such as a double defect f or a double skin defect b in which the molten metal flows into the deep constriction defect a and a deep solidified defect a. If surface defects such as such deep constriction defects a and double skin defects b are generated on the surface of the ingot 6, the surface of the ingot 6 needs to be cut (skinned). The yield is significantly reduced, and depending on the conditions, it cannot be used.
一方、本発明による適正な製造方法で、鋳塊６を製造した場合、表面に凹凸や割れなどの重大な欠陥が発生しにくく、割れやすい合金材料の代表であるＴｉＡｌ基合金であっても、比較的軽微（深さ５ｍｍ以内）で、使用上問題のないくびれ状欠陥ａしか生成されず、製造される鋳塊６は、鋳塊６として使用可能なものとなる。 On the other hand, when the ingot 6 is manufactured by an appropriate manufacturing method according to the present invention, serious defects such as irregularities and cracks are hardly generated on the surface, and even a TiAl-based alloy that is representative of an alloy material that easily breaks, Only a constricted defect a which is relatively minor (within a depth of 5 mm) and has no problem in use is generated, and the manufactured ingot 6 can be used as the ingot 6.
これら深いくびれ状欠陥ａや二重肌欠陥ｂ、割れ状欠陥等の凝固欠陥の発生を防止するためには、適正な溶解鋳造の操業条件を選択することが不可欠である。操業条件に問題があると、凝固界面での凝固状況が急激に変化することがあり、凝固欠陥が発生する可能性が高くなる。特に、初装原料３ａを溶解し始めてから追加装入原料３ｂを供給するまでの初期操業時に、投入電力の変動や溶湯プール５の容量の変動があると、溶湯プール５の形状に直接的な影響を及ぼすこととなり、凝固欠陥の発生につながることがある。 In order to prevent the occurrence of solidification defects such as the deep constriction defect a, double skin defect b, and crack defect, it is indispensable to select an appropriate operation condition for melting and casting. If there is a problem in the operating conditions, the solidification state at the solidification interface may change abruptly, and the possibility of occurrence of solidification defects increases. In particular, if there is a change in input power or a change in the capacity of the molten pool 5 during the initial operation from the start of melting the initial charged raw material 3a to the supply of the additional charged raw material 3b, the shape of the molten pool 5 is directly affected. May cause solidification defects.
特にコールドクルーシブル誘導溶解装置Ａを用いて、鋳塊６を引き抜く方法で鋳塊６を製造する場合は、凝固欠陥の発生がないように、初期操業時の溶解電力を規定することが肝要であるといえる。 In particular, when the ingot 6 is manufactured by the method of pulling out the ingot 6 using the cold crucible induction melting apparatus A, it is important to define the melting power at the initial operation so that no solidification defects occur. It can be said.
以下、本発明が完成するまでの経緯について詳細に説明する。 Hereinafter, the process until the present invention is completed will be described in detail.
コールドクルーシブル誘導溶解法で、大型の鋳塊６を製造する際の原料となる溶解原料３（初装原料３ａ）を溶解する場合、まず、高周波コイル４に高周波電流を通電し、その初装溶解原料３に発生する誘導電流の抵抗発熱によって、その溶解原料３を加熱し、その加熱温度を溶解原料３の融点（液相線）以上まで上昇させて溶解原料３を溶解することにより溶湯プール５を形成する。その際、図２に示すように、その溶湯プール５内では、誘導磁場による中心方向への磁気力（横向き矢印で示す）が作用して、溶湯静圧（下向き矢印で示す）と釣り合うようになると想定される。原理的には、磁気力と溶湯静圧が釣り合う位置で、溶湯プール５の溶湯が、水冷銅製るつぼ２の内壁面に接触して凝固層１２が形成され始めることになるが、溶湯プール５は電磁気力によりその中央部で盛り上がり、表面を溶湯が流れ落ちるような激しい流動をしている。その結果、溶湯の一部が、前記した釣り合いの位置より更に上方で水冷銅製るつぼ２の内壁面に接触して、形成される凝固層１２は上下に長くなり、凝固層１２で囲まれた内側に溶湯プール５が形成されたような状態となる。 When melting the melting raw material 3 (initial raw material 3a), which is a raw material for manufacturing a large ingot 6, by the cold crucible induction melting method, first, a high frequency current is applied to the high frequency coil 4 and the initial melting is performed. The molten raw material 3 is heated by the resistance heat generation of the induced current generated in the raw material 3, and the molten raw material 3 is melted by raising the heating temperature to the melting point (liquidus) of the molten raw material 3 or higher. Form. At that time, as shown in FIG. 2, in the molten metal pool 5, a magnetic force (indicated by a horizontal arrow) due to the induced magnetic field acts to balance the molten metal static pressure (indicated by a downward arrow). It is assumed that In principle, the molten metal in the molten pool 5 comes into contact with the inner wall surface of the water-cooled copper crucible 2 at a position where the magnetic force and the static pressure of the molten metal are balanced, and the solidified layer 12 starts to be formed. It swells in the center due to electromagnetic force, and it has a violent flow such that the molten metal flows down the surface. As a result, a part of the molten metal comes into contact with the inner wall surface of the water-cooled copper crucible 2 above the above-described balance position, and the formed solidified layer 12 is elongated vertically, and the inner side surrounded by the solidified layer 12 In this state, the molten metal pool 5 is formed.
このような状態で、水冷銅製るつぼ２のるつぼ底１を下方に移動させると、表層に形成された凝固層１２と共に、溶湯プール５が下方に引き抜かれる。しかしながら、上下に長い凝固層１２が形成されている場合、図３に示すように、表層の凝固層１２の一部が、水冷銅製るつぼ２を構成する銅製セグメント７、７間に設けられたスリット１３（図２に示す）に食い込んだような状態となることがあり、特に水冷銅製るつぼ２の内壁面に強固に固着している場合（図３に○で示す）、固着した部位は引き下げられないことになる。その結果、凝固層１２の下部に引っ張り応力が作用することとなり、凝固層１２の下部に亀裂が発生し、その亀裂が成長して大きく深いくびれ状欠陥ａが形成されてしまう。特に溶湯プール５の体積（容量）が大きくて深い状態ではこの影響が助長され、くびれ状欠陥ａの発生確率は更に高くなると考えられる。 In such a state, when the crucible bottom 1 of the water-cooled copper crucible 2 is moved downward, the molten metal pool 5 is drawn downward together with the solidified layer 12 formed on the surface layer. However, when a long solidified layer 12 is formed vertically, as shown in FIG. 3, a part of the solidified layer 12 on the surface layer is a slit provided between the copper segments 7 and 7 constituting the water-cooled copper crucible 2 13 (shown in FIG. 2), and when it is firmly fixed to the inner wall surface of the water-cooled copper crucible 2 (shown by a circle in FIG. 3), the fixed part is pulled down. There will be no. As a result, a tensile stress acts on the lower portion of the solidified layer 12, a crack is generated at the lower portion of the solidified layer 12, and the crack grows to form a large and deep constricted defect a. In particular, when the volume (capacity) of the molten metal pool 5 is large and deep, this effect is promoted, and it is considered that the probability of occurrence of the constricted defect a is further increased.
尚、図３に示すように、追加装入原料３ｂの下端を溶湯プール５に浸漬すると、溶解電力は急激に上昇し、水冷銅製るつぼ２の内壁面に接触して形成された凝固層１２に悪影響を及ぼし、その結果、くびれ状欠陥ａが発生すると考えられる。また、溶湯プール５の体積（容量）が大きいほどくびれ状欠陥ａの発生の可能性は高くなるため、初装原料３ａを溶解することにより形成した初期の溶湯プール５の引き抜き時においても、溶解電力を抑えて操業することが望ましいと考えられる。 In addition, as shown in FIG. 3, when the lower end of the additional charging raw material 3b is immersed in the molten metal pool 5, the melting power rises rapidly, and the solidified layer 12 formed in contact with the inner wall surface of the water-cooled copper crucible 2 is formed. It is considered that a constricted defect a occurs as a result of adverse effects. Moreover, since the possibility of the occurrence of the constriction defect a increases as the volume (capacity) of the molten metal pool 5 increases, even when the molten metal pool 5 formed initially by melting the initial raw material 3a is melted, it is dissolved. It is considered desirable to operate with low power.
前記したように、くびれ状欠陥ａは、溶湯プール５の表層に形成された凝固層１２が水冷銅製るつぼ２の内壁面に強固に固着される結果、その凝固層１２の下方が引っ張り応力を受けることで亀裂が発生し、その亀裂が成長することにより形成される。 As described above, the constriction defect “a” is caused by the fact that the solidified layer 12 formed on the surface layer of the molten metal pool 5 is firmly fixed to the inner wall surface of the water-cooled copper crucible 2. Thus, a crack is generated, and the crack grows to form.
従って、このようなくびれ状欠陥ａの発生を防止するためには、水冷銅製るつぼ２の内壁面に強固に固着する凝固層１２の領域を減少させることが有効と考えられる。凝固層１２は、磁気力と溶湯静圧が釣り合う位置より上側にも形成され、その領域が上方に長くなるほど、亀裂が発生する頻度も増加する。このようなくびれ状欠陥ａの生成を防止するためには、溶湯プール５の容量を少なくすることにより、凝固層１２の上方への成長を防止し、水冷銅製るつぼ２の内壁面へ付着する凝固層１２の領域を少なくすることが有効であると考えられる。 Therefore, in order to prevent the occurrence of the constricted defect a, it is considered effective to reduce the region of the solidified layer 12 firmly fixed to the inner wall surface of the water-cooled copper crucible 2. The solidified layer 12 is also formed above the position where the magnetic force and the static pressure of the molten metal are balanced, and the frequency of cracks increases as the region becomes longer upward. In order to prevent the formation of the constricted defect a, the capacity of the molten metal pool 5 is reduced to prevent the solidified layer 12 from growing upward, and the solidification adhered to the inner wall surface of the water-cooled copper crucible 2. It is considered effective to reduce the area of the layer 12.
一般的な大型の鋳塊６を製造する際のコールドクルーシブル誘導溶解法−重力鋳造法の場合は、極力多量の溶湯プール５を形成させることが高効率となるため、高周波コイル４による誘導加熱領域の全域、即ち高周波コイル４の全高さ範囲に溶湯プール５が存在するように、溶解原料３が装入される。 In the case of the cold crucible induction melting method-gravity casting method when manufacturing a general large ingot 6, it is highly efficient to form a molten metal pool 5 as much as possible. The molten raw material 3 is charged so that the molten metal pool 5 exists in the entire height range of the high frequency coil 4.
溶湯プール５の形状は、前記したように、中央部が盛り上がるドーム状であるが、その溶湯プール５の体積（容量）は、水冷銅製るつぼ２の内部で円柱状になると仮定したときの仮想溶湯プールの高さ（ｈ）を用いて表すことができる。 As described above, the shape of the molten metal pool 5 is a dome shape in which the center portion rises, but the volume (capacity) of the molten metal pool 5 is assumed to be a cylindrical shape inside the water-cooled copper crucible 2. It can be expressed using the height (h) of the pool.
一般的な大型の鋳塊６を製造する際のコールドクルーシブル誘導溶解法−重力鋳造法で用いられる溶湯プール５の体積（容量）は、仮想溶湯プールの高さ（ｈ：単位ｍｍ）と、高周波コイル４の全長（Ｌ：単位ｍｍ）との関係において、０．６＜ｈ／Ｌ＜０．９という数式を満たす範囲である。 The volume (capacity) of the molten pool 5 used in the cold crucible induction melting method-gravity casting method when producing a general large ingot 6 is the height (h: unit mm) of the virtual molten pool and the high frequency. In the relationship with the total length (L: unit mm) of the coil 4, the range satisfies the formula 0.6 <h / L <0.9.
しかしながら、本発明のようなコールドクルーシブル誘導溶解法−引き抜き鋳造法において、溶湯プール５の容量を、前記コールドクルーシブル誘導溶解法−重力鋳造法と同じ量とすれば、水冷銅製るつぼ２の内壁面へ付着する凝固層１２の領域が上下に長くなり、鋳塊６の表面に、くびれ状欠陥ａや二重肌欠陥ｂ等の表面欠陥が生成される可能性が高くなる。 However, in the cold crucible induction melting method-drawn casting method as in the present invention, if the capacity of the molten metal pool 5 is the same as that of the cold crucible induction melting method-gravity casting method, the inner wall surface of the water-cooled copper crucible 2 is used. The region of the solidified layer 12 to be attached becomes longer in the vertical direction, and the possibility that surface defects such as a constricted defect a and a double skin defect b are generated on the surface of the ingot 6 increases.
従って、本発明のようなコールドクルーシブル誘導溶解法−引き抜き鋳造法の場合は、水冷銅製るつぼ２の内壁面へ付着する凝固層１２の領域を少なくすることが、鋳塊６の表面に表面欠陥を生成させないための対策として有効であると考え、実際に溶湯プール５の体積（容量）を変えて試験操業を行った。その結果、表面欠陥を生成しにくくするためには、溶湯プール５が水冷銅製るつぼ２の内部で円柱状になると仮定したときに、仮想溶湯プールの高さ（ｈ：単位ｍｍ）と、高周波コイル４の全長（Ｌ）の関係が、０．１５＜ｈ／Ｌ＜０．５という数式を満たす範囲となることが有効であることが分かった。 Therefore, in the case of the cold crucible induction melting method-drawing casting method as in the present invention, reducing the region of the solidified layer 12 adhering to the inner wall surface of the water-cooled copper crucible 2 can cause surface defects on the surface of the ingot 6. Considering that it is effective as a countermeasure for preventing the generation, the test operation was actually performed by changing the volume (capacity) of the molten metal pool 5. As a result, in order to make it difficult to generate surface defects, when it is assumed that the molten metal pool 5 has a cylindrical shape inside the water-cooled copper crucible 2, the height (h: unit mm) of the virtual molten metal pool and the high frequency coil It was found that it is effective that the relationship of the total length (L) of 4 is in a range satisfying the mathematical formula of 0.15 <h / L <0.5.
しかしながら、溶湯プール５の体積が０．１５＜ｈ／Ｌ＜０．５という数式を満たす範囲内となるようにして操業しても、実際の操業では、様々な条件で溶湯プール５の体積（容量）が変動することがある。更に検討を進めた結果、この溶湯プール５の体積（容量）に見合う溶解電力の負荷量も鋳塊６の表面品質に大きくかかわっていることが分かった。特に、初装原料３ａを溶解する際の溶解電力が大きすぎると、初期の溶湯プール５の形状が大きく変化し、凝固層１２の領域が上下に長くなることで、表面欠陥等の鋳造欠陥が生成される可能性が高くなる。 However, even if the operation is performed so that the volume of the molten metal pool 5 falls within a range that satisfies the formula of 0.15 <h / L <0.5, the actual volume of the molten metal pool 5 under various conditions ( (Capacity) may fluctuate. As a result of further investigations, it was found that the load amount of the melting power corresponding to the volume (capacity) of the molten metal pool 5 is greatly related to the surface quality of the ingot 6. In particular, if the melting power when melting the initial raw material 3a is too large, the shape of the initial molten pool 5 is greatly changed, and the region of the solidified layer 12 becomes longer in the vertical direction, thereby causing casting defects such as surface defects. It is more likely that it will be generated.
特に、追加装入原料３ｂの下端を溶湯プール５に浸漬させるまでの溶解電力は、追加装入原料３ｂと比較して小さな容量の初装原料３ａ等を溶解できれば足りるため、追加装入原料３ｂの下端を溶湯プール５に浸漬させた後の定常時の溶解電力と比較すると、ある程度低い電力値であっても問題はない。具体的には、追加装入原料３ｂの下端を溶湯プール５に浸漬させる直前の溶解電力を、追加装入原料３ｂの下端を溶湯プール５に浸漬させた後の定常時の溶解電力を１００％とした場合８５％以上９５％未満の範囲に制御すれば、初期操業時に形成されるクビレ欠陥の発生を抑制することができる。 In particular, the melting power required to immerse the lower end of the additional charging raw material 3b in the molten metal pool 5 only needs to be able to dissolve the initial charging raw material 3a having a smaller capacity compared to the additional charging raw material 3b. There is no problem even if the power value is somewhat lower than the melting power in a steady state after the lower end of the steel is immersed in the molten metal pool 5. Specifically, the melting power immediately before immersing the lower end of the additional charging raw material 3b in the molten metal pool 5 is 100% of the melting power at the steady state after the lower end of the additional charging raw material 3b is immersed in the molten metal pool 5. If it is controlled within the range of 85% or more and less than 95%, it is possible to suppress the occurrence of constriction defects formed during the initial operation.
初装原料３ａ等を溶解して初期の溶湯プール５を形成した後、るつぼ底１を下方に移動させ、溶湯プール５が所定の容量に達したら、追加装入原料３ｂをその下端から順次溶湯プール５に装入する。その装入速度を、溶湯プール５を誘導加熱領域外に引き抜く量に見合った量だけ溶解するように制御して、追加装入原料３ｂを連続的に装入していくが、溶解電力は追加装入原料３ｂの下端を浸漬すると略同時に上昇していくので、そのオーバーシュートを緩和するためにも、追加装入原料３ｂの下端を溶湯プール５に浸漬させるまでの溶解電力は、出来るだけ低く抑えておく必要がある。 After the initial raw material 3a and the like are melted to form the initial molten pool 5, the bottom 1 of the crucible is moved downward, and when the molten pool 5 reaches a predetermined capacity, the additional charged raw material 3b is sequentially melted from the lower end. Charge the pool 5. The charging speed is controlled so as to melt by an amount commensurate with the amount with which the molten metal pool 5 is pulled out of the induction heating area, and the additional charging raw material 3b is continuously charged, but the melting power is added. When the lower end of the charging raw material 3b is immersed, it rises almost simultaneously. Therefore, in order to alleviate the overshoot, the melting power until the lower end of the additional charging raw material 3b is immersed in the molten metal pool 5 is as low as possible. It is necessary to keep it down.
このように追加装入原料３ｂの下端を溶湯プール５に浸漬させるまでは極力溶解電力を低く抑え（定常時の溶解電力を１００％とした場合８５％以上９５％未満の範囲に制御し）、追加装入原料３ｂの下端を溶湯プール５に浸漬させた後は定常時の溶解電力とし、追加装入原料３ｂの供給速度と鋳塊６の引き抜き速度を適宜調整しながら鋳塊６を製造することで、初期操業時に形成されるクビレ欠陥の発生を抑制できることがわかり、本発明を完成させた。 In this way, until the lower end of the additional charging raw material 3b is immersed in the molten metal pool 5, the melting power is kept as low as possible (controlled to a range of 85% or more and less than 95% when the melting power in the steady state is 100%), After the lower end of the additional charging raw material 3b is immersed in the molten metal pool 5, the ingot 6 is manufactured while adjusting the supply speed of the additional charging raw material 3b and the drawing speed of the ingot 6 as appropriate by using the melting power at the steady state. As a result, it was found that the occurrence of a neck defect formed during the initial operation can be suppressed, and the present invention has been completed.
尚、特許文献３に記載していると同様に、定常時の鋳塊６の引き抜きは、追加装入原料３ｂの供給速度と鋳塊６の引き抜き速度を適宜調整しながら、溶解電力を制御範囲の±５％の範囲とすれば、引き抜きに伴うくびれ状欠陥ａや二重肌欠陥ｂといった凝固欠陥の発生を抑制することができる。 Note that, as described in Patent Document 3, the ingot 6 is drawn out in a steady state while the supply power of the additional charging raw material 3b and the drawing speed of the ingot 6 are appropriately adjusted, and the melting power is controlled within a control range. If it is within the range of ± 5%, it is possible to suppress the occurrence of coagulation defects such as constriction defect a and double skin defect b associated with drawing.
以下、実施例を挙げて本発明をより具体的に説明するが、本発明はもとより下記実施例によって制限を受けるものではなく、本発明の趣旨に適合し得る範囲で適宜変更を加えて実施することも可能であり、それらは何れも本発明の技術的範囲に含まれる。 EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and the present invention is implemented with appropriate modifications within a range that can meet the gist of the present invention. These are all included in the technical scope of the present invention.
コールドクルーシブル誘導溶解装置を用いて、鋳塊を下方に引き抜く方法で鋳塊を製造する試験を実施した。試験ではコイル電圧を一定値に保持した条件下で、投入電力の変動に応じて、溶解原料の降下速度（装入速度）を変化させたり、或いは、鋳塊の引き抜きを一時停止させたりして鋳塊を製造した。使用したコールドクルーシブル誘導溶解装置等の基本仕様は以下に示す通りである。 The test which manufactures an ingot by the method of pulling out an ingot downward using the cold crucible induction melting apparatus was implemented. In the test, under the condition that the coil voltage is held at a constant value, the descending speed (charging speed) of the melting raw material is changed according to the fluctuation of the input power, or the ingot drawing is temporarily stopped. An ingot was produced. The basic specifications of the cold crucible induction melting apparatus used are as shown below.
コールドクルーシブル誘導溶解装置は、周波数：３０００Ｈｚ、出力：５００ｋＷ（Ｍａｘ）の高周波電源を有しており、整合盤を介して、水冷ケーブルにより高周波コイルと接続されている。高周波コイルは水冷銅製るつぼの外周を７周に亘り取り巻いており、その高さは２５６ｍｍである。水冷銅製るつぼは、円筒状に組まれた２４本の水冷銅製セグメントと、引き抜き機構に取り付けられたるつぼ底より構成されている。水冷銅製セグメント、るつぼ底等の内部には冷却水が流されており、その冷却水の流量は４００Ｌ／ｍｉｎである。また、コールドクルーシブル誘導溶解装置が収容された真空チャンバーの内容量は１０ｍ３である。 The cold crucible induction melting apparatus has a high frequency power source having a frequency of 3000 Hz and an output of 500 kW (Max), and is connected to a high frequency coil by a water-cooled cable via a matching panel. The high-frequency coil surrounds the outer periphery of the water-cooled copper crucible over 7 turns, and its height is 256 mm. The water-cooled copper crucible is composed of 24 water-cooled copper segments assembled in a cylindrical shape and the crucible bottom attached to the drawing mechanism. Cooling water is flowing inside the water-cooled copper segment, the crucible bottom, etc., and the flow rate of the cooling water is 400 L / min. The internal volume of the vacuum chamber in which the cold crucible induction melting apparatus is accommodated is 10 m 3 .
製造する鋳塊の材質は、ＴｉＡｌ基合金（Ｔｉ−３０Ａｌ−３Ｃｒ−３Ｖ−４Ｍｎ合金（質量％））とし、内径が２５０ｍｍの水冷銅製るつぼを用いて鋳塊を製造した。 The material of the ingot to be manufactured was a TiAl-based alloy (Ti-30Al-3Cr-3V-4Mn alloy (mass%)), and the ingot was manufactured using a water-cooled copper crucible having an inner diameter of 250 mm.
鋳塊の製造は、るつぼ底の上面に、溶解開始時のスタート材となる工業用純チタン材で成る底盤を取り付け、底盤の上面を高周波コイルの下端部より５〜２０ｍｍ上方の位置に配置した状態で、水冷銅製るつぼの内部に、製造される鋳塊と同じ金属材料で成る２０〜２５ｋｇの初装原料を装入して開始する。 For the production of the ingot, a bottom plate made of an industrial pure titanium material that is a starting material at the start of melting is attached to the top surface of the crucible, and the top surface of the bottom plate is arranged at a position 5 to 20 mm above the lower end of the high-frequency coil. In this state, 20 to 25 kg of the initial material made of the same metal material as the ingot to be manufactured is charged into the inside of the water-cooled copper crucible.
追加装入原料も初装原料と同様に鋳塊と同じ金属材料（Ｔｉ−３０Ａｌ−３Ｃｒ−３Ｖ−４Ｍｎ合金（質量％））で成るが、この実施例では束状ではなく１本の棒状鋳塊を用いた。その直径は２００ｍｍ、長さは１０００ｍｍで、質量は約１１０ｋｇである。尚、この追加装入原料は、真空チャンバーの上部に設けられた吊り下げ機構に吊り下げた状態で、その下端から水冷銅製るつぼの内部に順次連続して供給する。 The additional charging raw material is made of the same metal material (Ti-30Al-3Cr-3V-4Mn alloy (mass%)) as the ingot as in the case of the initial loading raw material. A lump was used. Its diameter is 200 mm, its length is 1000 mm, and its mass is about 110 kg. In addition, this additional charging raw material is continuously supplied from the lower end to the inside of the water-cooled copper crucible while being suspended by a suspension mechanism provided at the upper part of the vacuum chamber.
まず、底盤の上面を前記した所定の位置に配置し、水冷銅製るつぼの内部に初装原料を供給した。次に、真空チャンバーの内部の空気を拡散ポンプで６．７×１０−２Ｐａになるまで真空排気した後、高純度Ａｒを最高７８ＫＰａになるまで充填して不活性ガス雰囲気とした。次いで、高周波電源の出力を入れて、５０ｋＷ（１０分間）→２００ｋＷ（１０分間）→２５０ｋＷ（１０分間）→３５０ｋＷ（１０分間）で保持して、初装原料と底盤の上部を溶解し、初期の溶湯プールを形成した。 First, the upper surface of the bottom plate was placed at the predetermined position described above, and the initial raw material was supplied into the water-cooled copper crucible. Next, the air inside the vacuum chamber was evacuated to 6.7 × 10 −2 Pa with a diffusion pump, and then filled with high-purity Ar to a maximum of 78 KPa to form an inert gas atmosphere. Next, turn on the output of the high frequency power supply and hold at 50 kW (10 minutes) → 200 kW (10 minutes) → 250 kW (10 minutes) → 350 kW (10 minutes) to dissolve the initial material and the upper part of the bottom plate, Formed a molten metal pool.
その後、出力を下げて一定時間保持するが、この時、すなわち追加装入原料の下端を溶湯プールに浸漬させる直前の溶解電力を、表１に示すように、追加装入原料の下端を溶湯プールに浸漬させた後の定常時の溶解電力１００％とした場合、８０％以上１０４％の範囲の６種類の電力値に夫々設定し、るつぼ底を下方に移動させることで溶湯プールが所定の容量になるまで引き抜きを行った。尚、引き抜き開始と共に溶湯プールの容量は減少してゆき溶解電力は変化するので、溶解電力が一定の電力値を維持するように調整した。 Thereafter, the output is lowered and held for a certain time. At this time, as shown in Table 1, the melting power immediately before immersing the lower end of the additional charging raw material in the molten pool is set at the lower end of the additional charging raw material. When the melting power at steady state after being immersed in 100% is set to six power values in the range of 80% or more and 104%, the molten metal pool has a predetermined capacity by moving the crucible bottom downward Pulled out until. In addition, since the capacity | capacitance of the molten metal pool decreased and melting power changed with the start of drawing | extracting, it adjusted so that melting power might maintain a fixed electric power value.
溶湯プールの容量が所定量になったのを確認した後、吊り下げ機構に吊り下げた追加装入原料を下方に下げてその下端から溶湯プール内に連続して装入した。尚、溶湯プールの容量が所定量を維持するように溶湯プールの下方への引き抜きも同時に開始した。追加装入原料の下端が溶湯プールに浸漬されると、表１に示すように、急激に溶解電力も上昇して最高の電力値を示した。この溶解電力は、追加装入原料の装入速度が遅いこともあり、引き抜きの進行と共に徐々に低下していくが、電力値が高い場合は溶湯プールの容量が減少するように、逆に電力値が低い場合は溶湯プールの容量を増やすように、追加装入原料の装入速度と引き抜き速度を夫々調整して操業を行った。その試験結果を表１に示す。 After confirming that the capacity of the molten pool reached a predetermined amount, the additional charged raw material suspended by the suspension mechanism was lowered downward and continuously charged into the molten pool from its lower end. In addition, pulling out downward of the molten metal pool was started at the same time so that the capacity of the molten metal pool was maintained at a predetermined amount. When the lower end of the additional charging raw material was immersed in the molten metal pool, as shown in Table 1, the melting power suddenly increased and the maximum power value was shown. This melting power may gradually decrease as the charging speed of the additional charging raw material is slow, and gradually decreases with the progress of drawing, but conversely, if the power value is high, the capacity of the molten metal pool decreases. When the value was low, the operation was carried out by adjusting the charging speed of the additional charging raw material and the drawing speed so as to increase the capacity of the molten metal pool. The test results are shown in Table 1.
表１によると、追加装入原料の下端を溶湯プールに浸漬させる直前の溶解電力を、追加装入原料の下端を溶湯プールに浸漬させた後の定常時の溶解電力と比較して、９６％〜１０５％の範囲の電力値とした比較例１〜３では、溶解電力の変動（最高の電力値が高い）が大きくなり、その結果、引き抜き後の鋳塊にくびれ状欠陥の発生が認められた。一方、追加装入原料の下端を溶湯プールに浸漬させる直前の溶解電力を、追加装入原料の下端を溶湯プールに浸漬させた後の定常時の溶解電力と比較して、８０％の電力値とした比較例４では、溶湯プールの表面に凝固が観察され、以後の操業自体ができなかった。 According to Table 1, the melting power immediately before immersing the lower end of the additional charging raw material in the molten metal pool is 96% compared with the melting electric power at normal time after the lower end of the additional charging raw material is immersed in the molten metal pool. In Comparative Examples 1 to 3 in which the power value is in the range of ˜105%, the fluctuation of the melting power (the highest power value is high) becomes large, and as a result, the occurrence of constricted defects in the ingot after drawing is recognized. It was. On the other hand, the electric power value of 80% is compared with the electric power for melting just before the lower end of the additional charged raw material is immersed in the molten metal pool and the electric power for melting after the lower end of the additional charged raw material is immersed in the molten metal pool. In Comparative Example 4, the solidification was observed on the surface of the molten metal pool, and the subsequent operation itself was not possible.
これに対し、追加装入原料の下端を溶湯プールに浸漬させる直前の溶解電力を、追加装入原料の下端を溶湯プールに浸漬させた後の定常時の溶解電力と比較して、８５％以上９５％未満の範囲の電力値とした発明例１および２では、引き抜き後の鋳塊にくびれ状欠陥の発生は認められず、良好な鋳肌を呈していた。 On the other hand, the melting power immediately before immersing the lower end of the additional charging raw material in the molten metal pool is 85% or more in comparison with the melting electric power at normal time after the lower end of the additional charging raw material is immersed in the molten metal pool. In Invention Examples 1 and 2 having power values in the range of less than 95%, no constricted defects were observed in the ingot after drawing, and a good casting surface was exhibited.
１…るつぼ底
２…水冷銅製るつぼ
３…溶解原料
３ａ…初装原料
３ｂ…追加装入原料
４…高周波コイル
５…溶湯プール
６…鋳塊
７…銅製セグメント
８…高周波電源
９…引き抜き機構
１０…底盤
１１…吊り下げ機構
１２…凝固層
１３…スリット
ａ…くびれ状欠陥
ｂ…二重肌欠陥
Ａ…コールドクルーシブル誘導溶解装置
Ｂ…真空チャンバー
DESCRIPTION OF SYMBOLS 1 ... Crucible bottom 2 ... Water-cooled copper crucible 3 ... Melting raw material 3a ... Initial raw material 3b ... Additional charging raw material 4 ... High frequency coil 5 ... Molten pool 6 ... Ingot 7 ... Copper segment 8 ... High frequency power supply 9 ... Extraction mechanism 10 ... Bottom plate 11 ... Suspension mechanism 12 ... Solidified layer 13 ... Slit a ... Constriction defect b ... Double skin defect A ... Cold crucible induction melting device B ... Vacuum chamber
Claims (1)
前記水冷銅製るつぼの内部に上方より棒状溶解原料で成る追加装入原料を供給して、前記高周波コイルによる誘導加熱で前記棒状溶解原料で成る追加装入原料を下端から溶解しつつ、前記るつぼ底を下方に移動させて、前記溶湯プールを前記誘導加熱領域外に引き抜くことにより、前記溶湯プールを所定の容量を保たせた状態のまま、下方より凝固させて、長尺の鋳塊を製造する鋳塊の製造方法であって、
前記棒状溶解原料で成る追加装入原料の下端を前記溶湯プールに浸漬させる直前の溶解電力を、前記棒状溶解原料で成る追加装入原料の下端を前記溶湯プールに浸漬させた後の定常時の溶解電力を１００％とした場合８５％以上９５％未満の範囲の電力値として鋳塊を製造することを特徴とする鋳塊の製造方法。 The raw material supplied to the inside of the water-cooled copper crucible formed so that the bottom of the crucible can move up and down is melted by induction heating with a high-frequency coil surrounding the water-cooled copper crucible to form a molten metal pool. The molten metal pool on the bottom of the crucible by moving downward is pulled out of the induction heating area by the high frequency coil and solidified from below, to make the molten metal pool a predetermined capacity,
The crucible bottom is supplied to the inside of the water-cooled copper crucible from above with the additional charging raw material consisting of a rod-shaped melting raw material being melted from the lower end by induction heating by the high frequency coil. Is moved downward, and the molten pool is pulled out of the induction heating region, so that the molten pool is solidified from below while maintaining a predetermined capacity to produce a long ingot. A method for producing an ingot, comprising:
The dissolution power immediately before the lower end of the additional charging material consisting of rod-dissolved material is immersed in the molten metal pool, the bar dissolution of additional charging material consisting of raw material lower end of the steady state after being immersed in the melt pool A method for producing an ingot, wherein the ingot is produced with an electric power value in a range of 85% or more and less than 95% when the melting power is 100%.
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