EP0249050A1 - Process for the electroslag refining of metals, especially of such metals containing components with a high oxygen affinity - Google Patents
Process for the electroslag refining of metals, especially of such metals containing components with a high oxygen affinity Download PDFInfo
- Publication number
- EP0249050A1 EP0249050A1 EP87107038A EP87107038A EP0249050A1 EP 0249050 A1 EP0249050 A1 EP 0249050A1 EP 87107038 A EP87107038 A EP 87107038A EP 87107038 A EP87107038 A EP 87107038A EP 0249050 A1 EP0249050 A1 EP 0249050A1
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- European Patent Office
- Prior art keywords
- slag
- metals
- percent
- weight
- remelting
- Prior art date
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Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/16—Remelting metals
- C22B9/18—Electroslag remelting
Definitions
- the invention relates to a process for the electroslag remelting of metals which are at least 50 percent by weight in the form of at least one current-carrying melting electrode, in particular one with oxygen-affine alloy components, unmelted through a molten slag bath to form a block.
- the metallic starting material is remelted through a liquid or molten slag layer to an ingot or block, on the top of which a liquid zone, the so-called melting lake, is maintained.
- the block can be held stationary (in a so-called stand mold) or withdrawn continuously (from a so-called strand mold).
- the starting material can be added both in the form of a melting electrode and in the form of piece goods or particles.
- the melting and process heat is generated by the electrical resistance of the liquid slag, and the current can be supplied both by the melting electrode and (in the case of particulate starting material) by a special permanent electrode.
- the block and / or the mold is the electrical opposite pole. It is known to carry out the electroslag remelting process either by means of direct voltage or alternating voltage.
- the Ab requires that the ingots be manufactured by the well-known vacuum remelting process (VAR), since remelting under vacuum leads to relatively pure blocks that have a very low gas content.
- VAR vacuum remelting process
- the blocks are usually free of macro-segregation, some typical signs of segregation, such as “freckles", ring patterns and “white spots” can occur in the blocks. While segregation phenomena such as the "freckles" and ring patterns can be controlled more or less by carefully setting the melting parameters, the formation of the "white spots” appears to be independent of the melting conditions.
- Another source of the "white spots" which, according to the inventor's own experience, can consist of particles which can originate from the cast electrode if it is made of a superalloy which very often tears open along the stem crystals. It is therefore very difficult, if not impossible, to rule out these errors in a VAR block.
- the remelting is carried out under an overheated slag bath, the temperature of which is usually more than 300 ° C. above the liquidus temperature of the superalloy.
- the denidrite skeletons or the particles broken out of the electrode necessarily fall through the overheated slag and consequently have sufficient time to melt before they reach the melting lake.
- the invention is therefore based on the object of specifying a method of the type described at the outset in which oxidation is prevented, degassing takes place and neither "freckles", nor ring patterns, nor "white spots” occur. It is crucial that the task in question is solved simultaneously with regard to all subtasks.
- a protective gas atmosphere consisting of inert or inert gas
- a pressure of at most 900 mbar can be used.
- vacuum it is particularly useful to work in a pressure range between 200 and 10 ⁇ 2 mbar. In all cases there is sufficient degassing of the melt and any oxidation of the electrode metal and the alloy components is effectively eliminated without sacrificing the advantages of the ESR method in terms of a good block surface, metallurgical work and the avoidance of "white spots" must become.
- the slag composition is also of particular importance. So it is e.g. known from the literature that gaseous fluorine compounds continuously escape from slag mixtures with high fluorine contents due to the chemical reactions of the fluorine compound with oxidic slag contents. If such a slag with high fluoride contents were used under vacuum, the reaction would be shifted towards the formation of further volatile fluorides due to the lowering of the partial pressure, so that the process would be difficult to control.
- a slag which consists of at least 80 percent by weight of oxidic components whose boiling points are above 2000 ° C.
- the slag composition remains stable.
- Pure oxide systems such as, for example, come into question CaO, Al2O3 and MgO. It can be particularly advantageous to have CaO and Al2O3 at 48% each and MgO at 4% by weight.
- the height of the slag bath above the block was 70 mm.
- the slag consisted of 48 percent by weight of CaO and Al2O3 and 4 percent by weight of MgO.
- the electrode was operated with a voltage of 35 V and a current of 2300 A. operated. After a remelting period of 15 minutes under a vacuum of 5 ⁇ 10 ⁇ 1 mbar, the electrode was melted down to the remainder.
- the block removed from the mold after cooling had a clean, smooth surface and had no "crown".
- Cross-sectional images showed that the block was free of freckles, white spots and ring patterns over its entire length and its entire diameter.
- the alloy composition corresponded largely to that of the electrode, ie no erosion of aluminum and titanium was observed.
Abstract
Description
Die Erfindung betrifft ein Verfahren zum Elektroschlackeumschmelzen von Metallen, die zu mindestens 50 Gewichtsprozent in Form mindestens einer stromführenden Abschmelzelektrode, insbesondere einer solchen mit sauerstoffaffinen Legierungsbestandteilen, durch ein geschmolzenes Schlackenbad hindurch zu einem Block ungeschmolzen werden.The invention relates to a process for the electroslag remelting of metals which are at least 50 percent by weight in the form of at least one current-carrying melting electrode, in particular one with oxygen-affine alloy components, unmelted through a molten slag bath to form a block.
Beim Elektroschlackeumschmelzen wird das metallische Ausgangsmaterial durch eine flüssige bzw. geschmolzene Schlackeschicht hindurch zu einem Ingot oder Block umgeschmolzen, an dessen Oberseite eine flüssige Zone, der sogenannte Schmelzsee, aufrechterhalten wird. Der Block kann dabei stationär (in einer sogenannten Standkokille) festgehalten werden oder kontinuierlich (aus einer sogenannten Strangkokille) abgezogen werden. Das Ausgangsmaterial kann sowohl in Form einer Abschmelzelektrode zugesetzt werden, als auch in Form von Stückgut oder Partikeln. Die Schmelz- und Prozeßwärme wird durch den elektrischen Widerstand der flüssigen Schlacke erzeugt, wobei die Stromzufuhr sowohl durch die Abschmelzelektrode als auch (im Falle von partikelförmigem Ausgangsmaterial) durch eine besondere Permanentelektrode erfolgen kann. In der Regel ist der Block und/oder die Kokille der elektrische Gegenpol. Es ist bekannt, das Elektroschlackeumschmelzverfahren wahlweise mittels Gleichspannung oder Wechselspannung durchzuführen.In electroslag remelting, the metallic starting material is remelted through a liquid or molten slag layer to an ingot or block, on the top of which a liquid zone, the so-called melting lake, is maintained. The block can be held stationary (in a so-called stand mold) or withdrawn continuously (from a so-called strand mold). The starting material can be added both in the form of a melting electrode and in the form of piece goods or particles. The melting and process heat is generated by the electrical resistance of the liquid slag, and the current can be supplied both by the melting electrode and (in the case of particulate starting material) by a special permanent electrode. As a rule, the block and / or the mold is the electrical opposite pole. It is known to carry out the electroslag remelting process either by means of direct voltage or alternating voltage.
Durch die DE-OS 14 83 646 ist es bekannt, ds Elektroschlackeumschmelzverfahren auch unter unteratmosphärischem Druck, d.h. unter einem Druck unterhalb 1 bar durchzuführen. Für die Stromzuführung sind hierbei allerdings stets Permanentelektroden vorgesehen.From DE-OS 14 83 646 it is known that the electroslag remelting process also under subatmospheric pressure, i.e. to be carried out under a pressure below 1 bar. However, permanent electrodes are always provided for the power supply.
Für die Herstellung von Werkstücken mit hohen Anforderungen, insbesondere aus Superlegierungen für rotierende scheibenförmige Teile in Luftfahrttriebwerken, wird von den Ab nehmern verlangt, daß die Ingots durch das bekannte Vakuum-Umschmelzverfahren (VAR) hergestellt werden, da das Umschmelzen unter Vakuum zu relativ reinen Blöcken führt, die einen sehr geringen Gasgehalt aufweisen. Trotz der Tatsache, daß beim VAR-Verfahren aufgrund einer gerichteten Erstarrung die Blöcke normalerweise frei von Makroseigerungen sind, können einige typische Segregationserscheinungen, wie beispielsweise "Freckles", Ringmuster und "White Spots" in den Blöcken auftreten. Während Segregationserscheinungen wie die "Freckles" und Ringmuster mehr oder weniger durch sorgfältige Einstellung der Schmelzparameter beherrscht werden können, erscheint die Ausbildung der "White Spots" unabhängig von den Schmelzbedingungen zu sein. Kürzlich durchgeführte Untersuchungen haben gezeigt, daß die Ausbildung von "White Spots" nicht die Folge unregelmäßiger Erstarrungsbedingungen an der Erstarrungsfront sind. Es kann angenommen werden, daß die Bestandteile der "White Spots" folgende sind:
- Skelette aus Denidriten, die während des Abschmelzens von der gegossenen Abschmelzelektrode herabfallen,
- Teilchen, die von der sogenannten "Krone" am oberen Blockrand herunterfallen (die "Krone" ist ein dünner, scharfer Rand oberhalb des Schmelzsees durch Kondensation bzw. Erstarrung von Dämpfen und Spritzern),
- Ablösung von Teilchen von der Erstarrungskante des Schmelzsees.For the production of workpieces with high requirements, especially from super alloys for rotating disc-shaped parts in aviation engines, the Ab requires that the ingots be manufactured by the well-known vacuum remelting process (VAR), since remelting under vacuum leads to relatively pure blocks that have a very low gas content. Despite the fact that in the VAR process, due to directional solidification, the blocks are usually free of macro-segregation, some typical signs of segregation, such as "freckles", ring patterns and "white spots" can occur in the blocks. While segregation phenomena such as the "freckles" and ring patterns can be controlled more or less by carefully setting the melting parameters, the formation of the "white spots" appears to be independent of the melting conditions. Recent studies have shown that the formation of "white spots" is not the result of irregular solidification conditions on the solidification front. It can be assumed that the components of the "white spots" are as follows:
- skeletons of denidrites falling off the cast-off electrode during the melting process,
- particles falling from the so-called "crown" at the top of the block (the "crown" is a thin, sharp edge above the melting lake due to condensation or solidification of vapors and splashes),
- Detachment of particles from the solidification edge of the melting lake.
Eine weitere Quelle der "White Spots", die nach eigenen Erfahrungen des Erfinders aus Teilchen bestehen kann, die aus der gegossenen Elektrode Stammen können, wenn diese aus einer Superlegierung besteht, die sehr häufig entlang der Stengelkristalle aufreißt. Es ist daher sehr schwer, wenn nicht gar unmöglich, diese Fehler bei einem VAR-Block auszuschliessen.Another source of the "white spots" which, according to the inventor's own experience, can consist of particles which can originate from the cast electrode if it is made of a superalloy which very often tears open along the stem crystals. It is therefore very difficult, if not impossible, to rule out these errors in a VAR block.
Bei dem eingangs beschriebenen ESU-Verfahren wird das Umschmelzen unter einem überhitzten Schlackebad durchgeführt, dessen Temperatur üblicherweise mehr als 300 °C über der Liquidus-Temperatur der Superlegierung liegt. DieDenidriten-Skelette oder die aus der Elektrode herausgebrochenen Teilchen fallen notwendigerweise durch die überhitzte Schlacke und haben infolgedessen ausreichend Zeit zum Aufschmelzen, bevor sie den Schmelzsee erreichen. Auch gibt es beim ESU-Verfahren keine Ausbildung einer Krone am oberen Blockrand. Infolgedessen führt das ESU-Verfahren auch nicht zur Ausbildung von "White Spots".In the ESU process described at the outset, the remelting is carried out under an overheated slag bath, the temperature of which is usually more than 300 ° C. above the liquidus temperature of the superalloy. The denidrite skeletons or the particles broken out of the electrode necessarily fall through the overheated slag and consequently have sufficient time to melt before they reach the melting lake. There is also no formation of a crown at the top of the block in the ESU procedure. As a result, the ESU procedure does not lead to the formation of "white spots".
Obwohl die aus dem ESU-Verfahren hervorgegangenen Blöcke mindestens ebenso gut sind wie die aus dem VAR-Verfahren hervorgegangenen Blöcke, fordern die Abnehmer bei Superlegierungen regelmäßig die Anwendung des VAR-Verfahrens für die Herstellung rotierender Scheiben von Luftfahrtriebwerken. Der Grund hierfür ist darin zu sehen, daß bei den üblichen ESU-Verfahren nicht nur keine Entgasung des Materials stattfindet, sondern sogar in gewissen Fällen eine zusätzliche Gasaufnahme zu befürchten ist. Hierbei spielen Wasserstoff und Stickstoff die gefährlichste Rolle.Although the blocks resulting from the ESR process are at least as good as the blocks resulting from the VAR process, customers of superalloys regularly request the use of the VAR process for the production of rotating disks for aircraft engines. The reason for this is to be seen in the fact that not only does no degassing of the material take place in the usual ESR processes, but in certain cases there is even a fear of additional gas absorption is. Hydrogen and nitrogen play the most dangerous role here.
Eine weitere, sehr wesentliche, Gefahr besteht in der Bildung von Oxiden und oxidischen Einschlüssen durch Oxidation des Metalls, insbesondere der sauerstoffaffinen Legierungsbestandteile, durch den umgebenden Luftsauerstoff. Bei diesen sauerstoffaffinen Legierungsbestandteilen handelt es sich um die Elemente Aluminium, Bor, Titan, Zirkonium u.a. Durch die Oxidation derartiger Legierungsbestandteile entsteht dann ein entsprechender Mangel.Another, very important, danger is the formation of oxides and oxidic inclusions through oxidation of the metal, in particular the alloy components with an affinity for oxygen, by the surrounding atmospheric oxygen. These alloy components with an affinity for oxygen are the elements aluminum, boron, titanium, zirconium and others. A corresponding deficiency then arises from the oxidation of such alloy components.
Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren der eingangs beschriebenen Gattung anzugeben, bei dem eine Oxidation verhindert wird, eine Entgasung stattfindet und weder "Freckles", noch Ringmuster, noch "White Spots" auftreten. Es ist dabei ganz entscheidend, daß die betreffende Aufgabe im Hinblick auf alle Teilaufgaben gleichzeitig gelöst wird.The invention is therefore based on the object of specifying a method of the type described at the outset in which oxidation is prevented, degassing takes place and neither "freckles", nor ring patterns, nor "white spots" occur. It is crucial that the task in question is solved simultaneously with regard to all subtasks.
Die Lösung der gestellten Aufgabe erfolgt bei dem eingangs beschriebenen Verfahren erfindungsgemäß durch die Kombination der Merkmale, daß man
- a) den Umschmelzprozeß unter unteratmosphärischem Druck durchführt,
- b) als Schlacke eine zu mindestens 80 Gewichtsprozent oxidische Schlacke aus solchen Oxiden verwendet, deren Siedepunkte über 2000 °C liegen, und
- c) die Schlacke mittels Wechselstrom beheizt.
- a) carries out the remelting process under subatmospheric pressure,
- b) used as slag at least 80 percent by weight oxidic slag from oxides whose boiling points are above 2000 ° C, and
- c) the slag is heated by means of alternating current.
Sofern eine Schutzgasatmosphäre aus Inert- oder Edelgas verwendet wird, kann mit einem Druck von höchstens 900 mbar gearbeitet werden. Bei Verwendung von Vakuum ist es besonders zweckmäßig, in einem Druckbereich zwischen 200 und 10⁻² mbar zu arbeiten. In sämtlichen Fällen findet eine ausreichende Entgasung der Schmelze statt, und jegliche Oxidation des Elektrodenmetalls und der Legierungsbestandteile wird wirksam ausgeschaltet, ohne daß dabei auf die Vorteile des ESU-Verfahrens hinsichtlich einer guten Blockoberfläche, einer metallurgischen Arbeit und die Vermeidung der "White Spots" verzichtet werden muß.If a protective gas atmosphere consisting of inert or inert gas is used, a pressure of at most 900 mbar can be used. When using vacuum, it is particularly useful to work in a pressure range between 200 and 10⁻² mbar. In all cases there is sufficient degassing of the melt and any oxidation of the electrode metal and the alloy components is effectively eliminated without sacrificing the advantages of the ESR method in terms of a good block surface, metallurgical work and the avoidance of "white spots" must become.
Von ganz besonderer Bedeutung ist dabei auch die Schlackezusammensetzung. So ist es z.B. aus der Literatur bekannt, daß aus Schlackenmischungen mit hohen Fluoranteilen infolge der chemischen Reaktionen der Fluorverbindung mit oxidischen Schlackenanteilen laufend gasförmige Fluorverbindungen austreten. Würde man eine derartige Schlacke mit hohen Fluoridanteilen unter Vakuum verwenden, so würde aufgrund der Herabsetzung des Partialdrucks die Reaktion in Richtung auf die Bildung weiterer flüchtiger Fluoride verschoben, so daß der Prozeß schwer kontrollierbar würde.The slag composition is also of particular importance. So it is e.g. known from the literature that gaseous fluorine compounds continuously escape from slag mixtures with high fluorine contents due to the chemical reactions of the fluorine compound with oxidic slag contents. If such a slag with high fluoride contents were used under vacuum, the reaction would be shifted towards the formation of further volatile fluorides due to the lowering of the partial pressure, so that the process would be difficult to control.
Wenn man erfindungsgemäß eine Schlacke verwendet, die zu mindestens 80 Gewichtsprozent aus oxidischen Komponenten besteht, deren Siedepunkte über 2000 °C liegen, so bleibt die Schlackezusammensetzung stabil. In Frage kommen insbesondere reine Oxid-Systeme wie beispielsweise solche aus CaO, Al₂O₃ und MgO. Mit besonderem Vorteil können dabei CaO und Al₂O₃ zu je 48 % und MgO zu 4 Gewichtsprozent vorhanden sein.If, according to the invention, a slag is used which consists of at least 80 percent by weight of oxidic components whose boiling points are above 2000 ° C., the slag composition remains stable. Pure oxide systems such as, for example, come into question CaO, Al₂O₃ and MgO. It can be particularly advantageous to have CaO and Al₂O₃ at 48% each and MgO at 4% by weight.
Die Vorteile des erfindungsgemäßen Verfahrens lassen sich wie folgt darstellen:
- 1. Anwendung von Wechselstrom zur besseren Steuerung der gewünschten metallurgischen Reaktionen und zur Vermeidung von gleichgerichteten Magnetfeldern, die die Frecklesbildung im Umschmelzblock begünstigen würden,
- 2. Anwendung des Vakuums zur Beseitigung der Einflüsse von Wasserstoff und Stickstoff sowie zur Vermeidung der Oxidation von Schlacke und Metall,
- 3. Anwendung einer oxidischen, reaktionsfähigen Schlacke zur Erzielung eines besseren Reinheitsgrades als beim VAR-Verfahren und
- 4. Vermeidung von "White Spots".
- 1. use of alternating current to better control the desired metallurgical reactions and to avoid rectified magnetic fields which would favor the formation of freckles in the remelting block,
- 2. Use of the vacuum to eliminate the effects of hydrogen and nitrogen and to avoid the oxidation of slag and metal,
- 3. Use of an oxidic, reactive slag to achieve a better degree of purity than with the VAR process and
- 4. Avoidance of "white spots".
Eine Abschmelzelektrode aus Inconel 718, eine Nickel-Basis-Legierung mit hohen Gehalten an Titan und Aluminium, und mit einer Länge von 500 mm und einem Durchmesser von 90 mm wurde in einer wassergekühlten Standkokille mit einem Innendurchmesser von 150 mm zu einem Block umgeschmolzen. Die Höhe des Schlackenbades über dem Block betrug 70 mm. Die Schlacke bestand zu je 48 Gewichtsprozent aus CaO und Al₂O₃ und zu 4 Gewichtsprozent aus MgO. Die Elektrode wurde mit einer Spannung von 35 V und einer Stromstärke von 2300 A betrieben. Nach einer Umschmelzdauer von 15 Minuten unter einem Vakuum von 5 × 10⁻¹ mbar war die Elektrode bis auf einen Rest abgeschmolzen. Der nach Abkühlung aus der Kokille entnommene Block hatte eine saubere glatte Oberfläche und besaß keinerlei "Krone". Schnittbilder ergaben, daß der Block über seine gesamte Länge und seinen gesamten Durchmesser frei von Freckles, White Spots und Ringmustern war. Die Legierungszusammensetzung entsprach äußerst weitgehend derjenigen der Elektrode, d.h. es wurde keinerlei Abbrand von Aluminium und Titan beobachtet.A melting electrode made of Inconel 718, a nickel-based alloy with a high content of titanium and aluminum, and with a length of 500 mm and a diameter of 90 mm, was remelted into a block in a water-cooled stand mold with an inner diameter of 150 mm. The height of the slag bath above the block was 70 mm. The slag consisted of 48 percent by weight of CaO and Al₂O₃ and 4 percent by weight of MgO. The electrode was operated with a voltage of 35 V and a current of 2300 A. operated. After a remelting period of 15 minutes under a vacuum of 5 × 10⁻¹ mbar, the electrode was melted down to the remainder. The block removed from the mold after cooling had a clean, smooth surface and had no "crown". Cross-sectional images showed that the block was free of freckles, white spots and ring patterns over its entire length and its entire diameter. The alloy composition corresponded largely to that of the electrode, ie no erosion of aluminum and titanium was observed.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT87107038T ATE65551T1 (en) | 1986-06-07 | 1987-05-15 | METHOD FOR ELECTRIC SLAG REMELTING OF METALS, ESPECIALLY THOSE WITH OXYGEN-AFFINED ALLOY COMPONENTS. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3619293A DE3619293C2 (en) | 1986-06-07 | 1986-06-07 | Process for electroslag remelting of metals, in particular those with alloy components with affinity for oxygen |
| DE3619293 | 1986-06-07 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0249050A1 true EP0249050A1 (en) | 1987-12-16 |
| EP0249050B1 EP0249050B1 (en) | 1991-07-24 |
Family
ID=6302575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP87107038A Expired - Lifetime EP0249050B1 (en) | 1986-06-07 | 1987-05-15 | Process for the electroslag refining of metals, especially of such metals containing components with a high oxygen affinity |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4726840A (en) |
| EP (1) | EP0249050B1 (en) |
| JP (1) | JP2588895B2 (en) |
| AT (1) | ATE65551T1 (en) |
| DE (2) | DE3619293C2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2302551B (en) * | 1995-06-22 | 1998-09-16 | Firth Rixson Superalloys Ltd | Improvements in or relating to alloys |
| WO1999020804A1 (en) * | 1997-10-22 | 1999-04-29 | General Electric Company | Method for dissolution of nitrogen-rich inclusions in titanium and titanium alloys |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5332197A (en) * | 1992-11-02 | 1994-07-26 | General Electric Company | Electroslag refining or titanium to achieve low nitrogen |
| US6113666A (en) * | 1998-08-11 | 2000-09-05 | Jaroslav Yurievich Kompan | Method of magnetically-controllable, electroslag melting of titanium and titanium-based alloys, and apparatus for carrying out same |
| WO2001062992A1 (en) * | 2000-02-23 | 2001-08-30 | General Electric Company | Nucleated casting systems and methods |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1483646A1 (en) | 1965-06-11 | 1969-09-25 | Suedwestfalen Ag Stahlwerke | Method and device for the production of cast blocks, preferably steel blocks |
| US3777041A (en) * | 1972-03-24 | 1973-12-04 | British Iron Steel Research | Electroslag refining apparatus |
| US4117253A (en) | 1977-03-01 | 1978-09-26 | Wooding Corporation | High integrity atmosphere control of electroslag melting |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE795856A (en) * | 1972-02-24 | 1973-08-23 | Air Liquide | IMPROVEMENT OF THE ELECTRIC REFINING PROCESS BY DAIRY CALLED "E.S.R. PROCESS" |
| US3759311A (en) * | 1972-04-04 | 1973-09-18 | Allegheny Ludlum Steel | Arc slag melting |
-
1986
- 1986-06-07 DE DE3619293A patent/DE3619293C2/en not_active Expired - Fee Related
- 1986-08-15 US US06/896,937 patent/US4726840A/en not_active Expired - Lifetime
-
1987
- 1987-05-15 AT AT87107038T patent/ATE65551T1/en not_active IP Right Cessation
- 1987-05-15 DE DE8787107038T patent/DE3771586D1/en not_active Expired - Lifetime
- 1987-05-15 EP EP87107038A patent/EP0249050B1/en not_active Expired - Lifetime
- 1987-06-04 JP JP62139091A patent/JP2588895B2/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1483646A1 (en) | 1965-06-11 | 1969-09-25 | Suedwestfalen Ag Stahlwerke | Method and device for the production of cast blocks, preferably steel blocks |
| US3777041A (en) * | 1972-03-24 | 1973-12-04 | British Iron Steel Research | Electroslag refining apparatus |
| US4117253A (en) | 1977-03-01 | 1978-09-26 | Wooding Corporation | High integrity atmosphere control of electroslag melting |
Non-Patent Citations (2)
| Title |
|---|
| NEUE HÜTTE, Band 24, Nr. 4, April 1979, Seite 157, Nr. 2716, VEB Deutscher Verlag für Grundstoff-Industrie, Leipzig, DD; "Forschungsberichte des Landes Nordrhein-Westfalen" * |
| ZEITSCHRIFT, NEUE HÜTTE, vol. 4, April 1979 (1979-04-01), pages 157 |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2302551B (en) * | 1995-06-22 | 1998-09-16 | Firth Rixson Superalloys Ltd | Improvements in or relating to alloys |
| WO1999020804A1 (en) * | 1997-10-22 | 1999-04-29 | General Electric Company | Method for dissolution of nitrogen-rich inclusions in titanium and titanium alloys |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2588895B2 (en) | 1997-03-12 |
| US4726840A (en) | 1988-02-23 |
| ATE65551T1 (en) | 1991-08-15 |
| DE3771586D1 (en) | 1991-08-29 |
| DE3619293C2 (en) | 1993-10-14 |
| JPS63259031A (en) | 1988-10-26 |
| DE3619293A1 (en) | 1987-12-10 |
| EP0249050B1 (en) | 1991-07-24 |
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