CA1128590A - Method and apparatus for producing a solid-section ingot by electroslag remelting - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The method includes remelting consumable electrodes in a melting container and effecting a positive action upon crystallization of the ingot in the course of the melting operation, consisting in that a cooled body is brought into con-tact with the molten metal constituting the metal bath and the contact is maintained till the melting operation is complete by moving the cooled body at a speed close to the melting rate. On completion of the melting operation, the cooled body is extracted from the metal bath. The cooled body may be made in the form of a float or of an extension widened at the bottom and fixedly attached to a movable mould.

Description

s~f sackground of the Invention l. Field of the Invention.
.: , ` The present invention relates to the art of electrometal-lurgy and is specifically concerned with a method and appara-tus for the electroslag remelting process.

The invention is particularly applicable to producing large ingots.
~ 10 i- The term "melting operation", as used throughout the . specification and claims means the process of making one ingot by the electroslag remelting method.
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; 15 The term "melting rate" is used to suggest the rate of molten metal accumulution in a melting container in the course of electroslag remelting of one or more consumable electrodes, expressed th.rough the linear speed o~ movement of the metal ba-th surface along t.he height of the melting container.
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The term "metal bath depth" is used to suggest the dis-tance from the metal bath bottom, i.e. the solid-liquid in-terface in the ingot, to the metal bath surface, measured along the vertical axis of symmetry of the melting container . at the time moment under conslderation.

2. Description of the Prior Art When making a large solid-section ingot by the electro-slag remelting process, it is difficult to attain a compact ' fine-grained metal structure throughout the ingot volume, - -since in the course of crystallization due to decline in the : 35 , : - 2 - :~

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cooling effect of the bottom plate with the increase in height, the centre portion of the metal bath deepens consid-erably as the ingot grows, and the bath bottom acquires the shape of a deep steep-sided funnel; this favours development of ~egregation effects and entrapment of non-metallic inclu-sions in the centre portion of the ingot.
' Various attempts to control crystallization in the process of ingot making by exposing the metal bath to an electromagnetic field, ultrasound oscillations, or mechanical vibration which ensure breakdown of large crystals in the course of their grow-th have been undertaken for levelling the metal bath bottom with the aim of obtaining a sound metal structure.
However, said methods yield a stable effect only in making ingots of not more than 1000 mm in diameter and 2.5 m ; in height. Applying the methods Eor larger inyots entails yreat power losses and fails to yield any adequate results.
There has recently been developed a power modulation techniclue employed in particular in the method for producing an ingot by electroslag remelting, disclosed in U.K. Pat.
No. 1,421,393, Class H2H, 1976.
', 25 This method contemplates connecting each electrode or an electrode group to a separate power source. After steady-state remelting conditions have been attained, the current and voltage fed to each electrode or -to each electrode group are alterna-:. :
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tf~31y decreased and i~craased so that the power ol ~he curren-ft ~, . supplied alter~ately reaches the ma~imum and the minimu2f~f Thls 1 .
.~ procedure ~rovides ~or recurrent-pro~ressi~e or reciproca- -tin~ motion OL the mfaxi~um heat poi~t i~ f~he ~lag ba~h,f w~ich allows a homo~eneous~ compact) a~cl fi~e~-~;raiilefd structure o~ remelted metfal ~fo be ob~ai~ed~
~he above method iff~ applicab1f f Por large-~ectio~ i~f.f~OtS q ~f ~fUt ;yielfl~ a ~arked e~ffeffct or~ fVi~th ref1ative~ fhO~t o~efs~
fef~ides 9 itf~ applicatio~ is con~i~ed to/multielect~ode appara~us~
he method calls ~or c~ber~ome~ complicated, and costly oquipme~t i~cludin~ se~eral powe~ SOUrCe8 ~ mean~ ~or switching t~e~o, a lar~e numbor of current leads interferi~ with acc~
to the ~lorki~g el~ment~ of bhe ap~xatu~ a~d cau~in~ ~onside-rabl~ electric paNe~ lo~ses. ~:
,;, , , .~: Ulell know~ in the art areelectro~lag remelti~g apparatus : ~:
for ~roduci~g holloeJ ingots, which provide for a sound metal : -~t~
struc~ure owing to ~ presence in the meltin~ container o~ a cooled body ~eeded to fo~ a hollow i~ the i~o~. -,, , ~`here ha~ be~n pro~idod, for example~ an ~lectro~lag : :: `
remeltin~ ap~aratus for making hollow in~ots, compri~ a coo-:
l~d body in the Porm o~ a moulding core, linked to a liting '~ device9 i~ a ~ ing co~tai~er Yo~med b~ a mould ~nd a bo~tom - - : pla~e (see1 e~g. 9 U.B~ Pa~. ~o.3~807,487, Class 164-2529 1974).
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In a similar apparatus with a movable mould resting : in its lowermost position on a bottom plate to form therewith a melting container, the core is linked to the lifting device not directly but through the movable mould coupled with the lifting devi~ce, the core being fixedly attached to the mould (see B.E.Paton, V.R.Demchenko et al. "Matematicheskoe opisanie protesessa zatverdevania plogo elektroshlakovogo slitka" in "Rafinirujuschie pereplavy", cdited by B.E.Paton, Member of A.
Sc. of the USSR, No. 2, p~ 35, Fig. 2; Kiev, 1975).
The core in the above apparatus is provided with supporting members allowing the core~to.be secured to -the top end face of the movable mould and with an extension projection downwardly from the end face for a length exceeding that of the movable mould.

The apparatus of the above type also generally compr:ises a liquid metal level detector which is arranged in the wall of the movable mold for proclucing commands whi.ch provide the controls for controlling the vertical movement of the mov-. able mold in accordance with the movement of the slag-metal interface relative to the detector operation.
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The above-described apparatus are unfit for making solid-section ingots, since the cooled body (core) is arranged therein so as to prevent the molten metal of consumable ele.ctrodes from penetration into the core location zone when the core is moved, with the result that a hollow is Eormed in the ingot.
A considerable core-to-mol.ten slag contact area re-sults in great heat losses in the apparatus and hence in an addit;onal power consumption.

~5 The present invention provides a simple and economi-cally efficient method for producing solid-section ingots by ~' ., ,: -. .::

electroslag remelting, ensuring a compact fine-grained metal structure thr,o,ughout the whole ingot volume with any size of ingot.

The present invention also provides an electroslag remelting apparatus for producing ingots, which accomplishes said method with mi,nimum electric power consump-tion.

According to the present invention there is provided :L0 a method for producing a solid-section ingot by electroslag remelting of one or more consumable electrodes in a melting container with formation of metal bath moving upwardly as the ingot grows, including effecting apositive action upon ingot crystalliæation in the course o~ -the melting operation wherein, according to the invention, said action is accomplished by bri-ng-ing a cooled body into contact with the molten metal consti--tuting the metal bath so t.hat sa.id cooled body i.s disposed on the vertlcal axis of symmetry of -the melting containter and by ma.intaininy this unti:L the melting operation is comple-ted by moving said cooled body upwardly at a speed close to the melting rate, with subsequent extraction of said cooled body from the metal bath.

Introduction of the cooled body in-to the central portion of the ingot metal bath speeds up the crystallization process in this zone and promotes the levell.ing of the metal bath bottom which is the solidified front, creating thereby the conditions for unidirectional growth of crystals and forma-tion o~ a fine-grained compact structure throughout the ingot volume. ., Said operation involves no considerable power consump-tion and calls for no complicated equipment for'its accomplish-ment.
It is expedient that the cooled body be brought into '~

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contact with the mo:Lten metal bath prior the moment when sec~
tions inclined to a horizintal line at an angle o~ '15 are formed in the profile of the metal bath bottom and when such sections appe~r within the zone, transverse dimensions there-of on the metal bath surface amount to not less than 7596 of this surface . Said zone is normally symrne trica L with respect to the -vertical axis of symmetry of the rnelting container.

The above condition provides for the optimum direc-tion of crystal growth in the central portion of the ingot.
Introduci:ng the cooled body at a later stage of -the melting operation may bring about the appearance in the ingot of zones, wherein ,~ ~

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, ~: " . :, the direction of crystal growth makes an angle of over 75 with a vertical line, which entails emergence of aggregations of non-metallic inclusions, deteriorating the ingot strength.

To ensure homogeneity of the ingot structure, it is essential that the dep-th of immersion of the cooled body into the metal bath amount to not more than 60% of the bath depth at the moment preceding the immersion of the cooled body.
This depth may be achieved the moment the cooled body is immersed into the metal bath, or after the cooled body immersed into the bath has been momentarily thrust against the bath bottom and moved upwardly to the predetermined level at a speed exceeding the melting rate.

Inasmuch as a crust of solidified metal is formed on the cooled body surface and the direction of cryskal growth of the crust is oppo~ite to that of the crystals of the ingot bulk, a small distance between the cooled body and the metal bath bottom may result in that the thickness of the molten metal interlayer will be insufficient to melt down said crust.

It is to be noted that introducing the cooled body into the metal bath causes the profile of the bath bottom to change which may be accompanied by a shallowing of the bath.
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Im~ersi~g the cooled ~o~y to a d~pth exceedi~g the above~speci~ied one may ~ive rise to emerge~c~ i~ the in~ot o~ zones with multic~rec-tio~al cr~ætall:iæatio~ and9 as a co~seque~ce 9 of clisco~tinui4ies i~ the metal ~tructure~
~ he obaects of t~ inve~tio~ are a;Lso accom~lishe~
i~ an elec-broslag re~elting apparatus for Qroducin~ a solid--sec~ion ingot~ adapted to car~y out the above-described method and comprising in a melt,ing co~ainer9 formed by a mould a~d a bottom plateg a cooled boc~ di~posed o~ the vertical axis of sy~metr~ of said co~tai~er a~d con~ec~ed to a li~ g ~evice, wherein~ accordin~ to the i~ve~tion, said cooled bod~
is a float whose wei~rht i~ heavier tha~ that o~' the mo~te~
havi~ the volume equal to that o~ th~ float a~d lighter tha~ that o~ the molben metal havin~ th~ samc volume~
~he co~truction of the above apparatu~ enable~ solld- ~
sectio~ i~gots with a compact ~i~e-grained structure ~hrou~hou~ ~`
~he volum~ to be obtained; while th~ co~struction of the cooled bod7 allows for its sel~-po~i~ioning i~ the metal bath a~d ~or maintaining a co~tant depth o~ it~ lmmer~io~
into the bath~
With an ~ppropxiate con~iguratio~ of the float, whe~ to the surface area o~ its portio~ projecting above khe mctal bath sur~'ace is small and its innex ~pace to be fillad with :~
a cooli~ fluid is of~et dow~wardly, the-area of i~s contac~
with the slag bath c~n be minimi~ed to reduce the hea~ los~es due to ~he presence of the cooled bo~ in the melti~g contai~erO ~ ;~

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The cooled body has supportin~ members secured to the top end face of the movable mold, and an extension projecting in the downward direction from said end face by a length less than the height of the movable mold. The extension of the cooled body comprises a wide portion disposed below the level of liquid metal level detector location, a narrow portion disposed above said wide portion, and an intermediate portion whose surface is shaped close to a cone, and conjugates said narrow and wide portions, thereby providing for flow of molten metal drops down from the cooled body surface. The cooled body can also be de-fined by a pipe grating.

The extension of the cooled body can be shaped as a coil, and said coil can be a pipe bent to form a loop. Such pipe includes a horizontal portion where said pipe is bent circle-wise, and vertical inlet and outlet portions, disposed symmetrically with respect to the vertical axis of symmetry of the meltiny container, the horizontal plane of symmetry of the horizontal portion o the loop being disposed not lower than the level of the liquid metal level detector location, thereby éxcluding the possibility of freezing the cooled body to the crystallizing metal.

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The float may be provided with a counterweight to con-trol the depth.of its immersion into the metal bath, which ensures the optimum conditions for maintaining the cooled hody in contact with the molten metal constituting the metal bath under different conditions of the melting opera-tion and with different chemical composition of the ingots produced.

The float and counterweight may be mounted on opposite ends of a two-arm lever installed above the mould for rocking with respect to the latter.

The present invention also provides an electroslag remelting apparatus for producing a solid-section ingot lS intended to carry out the above-described method and compris-ing in the melting container, formed by a bottom plate and a movable mould in the lowermost position thereof, a coo:Led body having supporting members secured to the ~op end face of the mould and an extension projecting downwardly from said end face, and comprising also a liEting device for moving the movable mould and a liquid metal level detector connected w-ith said lifting device and installed in the movable mould wall, wherein, according to the invention, the cooled body extension is of a length less than the height of the movable mould and includes a wide portion disposed below the level of the liquid metal level detector location, a narrow portion disposed above said wide portion, and an intermedi-. ~

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ate portio . whos e sux~ace is shaped ~lo~e to a co~e and con ju~at~s tha ~arrow portion a~d the wide portio~, providing therek~ ~or ~low oî molte~ metal drops dow~ ~ro~ the cooled bod;y surîace.
The cons~ruc~ion of the above-describea ~paratus provi~
des for produci~lg therei;~ solid-sectio~ got~ wi~h a compact fi:~e-grained ~tructure throughou1; the whole i~got volume..
The relatiYo dimensions o~ the cool~d bod3~ extension and tha movable mould are such that said exte~sion does ~ot irlter~ere with :Eillir~; by molten m~tal of the space previously occupied by the extenslon aIld then leît by the la tter due to its mo~ement. ~he shape oî the e~ensio~ arrow in iks u~pper portion and wide i~ its lowe~ ~orkion, provides for the op- ;
timum contact ~ith the molt~ m~t~l and a~ th~ same tim~t owing to a reduced ex~en~ion-to-~lag bath contact area ~ cuts down the powor losses caused by the pre~ce o~ the cooled body i~ the melting co~ainer. ~ -The above-described apparatus iæ simple i~ co~strustio~.
Inao.much as the cooled body is not a mouldi~g ~le~e~ and no stri~gent re~uirement~ as to ~tre~th are placed upo~ it, it i~ advantageouæ ~hat it be as light as po~sible a~d ha~e th~ ~orm o~ a pipe gratl~ o~ coil~ .
The coil may be a pipe bent i~ ~he form o~ a loop.
ith a circula~ cross-section ~ould5 such a loop may , i~clude a horizon~al portion where said pipe i~ bent substa~

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tially circlewise~ and ~ertical inlet and outlet portions disposed symmetrically with respect to the vertical axis of ;
symmetry of the melting container. In this case it is essen-tial that the horizontal plane of symmetry of the hori~ontal portion of the loop be disposed not lower than the level of the liquid metal level detector location to exclude the possibility of freezing the cooled ~ody to the crystallizing metal of the ingot.

~rief Description of the Drawings The invention will now be explained with reference to particular em~odiments thereof taken in conjunction with the accompanying drawings, wherein:
Fig. 1 is a diagram illustrating the principle of the method ~or pro~ucing a solid-section ingot hy ~electroslag remelting according to the invention;

Fig. 2 is a partially cut-away diagrammatic view of an electroslag remelting apparatus for producing an ingot accord-ing to the method of the invention;

Fig. 3 is a partially cut-away diagrammatic view of another electroslag remelting apparatus for producing an ingot according -to the method of the inventioni Figs. 4-9 illustrate variously shaped modifications of the cooled body in the apparatus shown in Fig. 3;

j E'ig. 4, in the form of a grating made up of pipes;

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o Fig. 5, in the form of a helical coil;

Fi~. 6, in the form of a pipe bent into a loop;

Fig. 7 is a sectional view taken along the line VII-VII
in Fig. 6;

Fig. 8, in the form of a pipe bent into a loop having a horizontal portion and vertical portions;
Fig. 9 is a sectional view taken along the line IX-I~
in Fig. 8;

Fig. 10 a, b, c represents graphs where calculated liquidus isotherms at different stages of the melting opera-tion for ingots of difEerent sixes and shapes are plotted;

a - or a 1100-mm-diame-ter cylindrical ingot;

b - for a 2700-mm-diameter cylindrical ingot;

c - for a 250 x 1100-mm rectangular cross-section ingot.

Detailed Description of the Invention A method for producing a solid-section ingot by electro-slag remelting is as follows:

A slag bath 4 tFig. 1) is established in a conventional manner in a melting container 1 formed by a mould 2 and a bottom plate 3. Consuma~le elec-trodes 5 are immersed into the slag bath and supplied with electric current. On passing the current, the slag bath 4 heats up and melts the consum-able electrodes 5. Drops of liquid metal from -the ends of the consumable electrodes 5 flow down towards the bottom plate 3, forming a metal ... . . . . . . , :~:

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bath 6. The molten metal of the metal bath 6 cools down and crystallizes at the cooled walls of the mould 2 and in the immediate vicinity of the cooled bottom plate 6. The cry- -stallized metal forms the bottom of the metal bath 6. The effect of the cooled bottom plate 3 reduces with the height of the melting container 1, while the efEect of the cooled walls of the mould 2 remains unchanged. As a result, the bottom profile of the metal bath.6 changes as the ingot grows. The centre of -the bottom starts deepening and the bottom tends to ac~uire the shape of a conical funnel. As ~ soon as the first signs of such a change appear, a cooled ; body 8 is contacted with the molten metal of the meta:L
bath 6.

The change in the bottom profile of the rnetal bath 6 duriny ingot making is determined experimentally or with the use of theoretical calculat.ions be:Eore starting -the melting operation. ~n the experimental determination a test ingot is previously rnade in -the same melting container without immersing the cooled body -therein but under the specified melting conditions, following which the process of change in the metal bath bottom profile is ascertained from the direction of crystal growth on the longitudinal section of the -test ingot and the opti-30 :~

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mum moment for immer$ing the cooled body and the possible depth of its immersion are determined on this basis.

The theoretical determination of the metal bath bottom profile at different moments of the melting operation involves plotting the liquidus isotherms calculated by a conventional procedure ~see s.E.Paton, V.F.Demchenko, Ju.G.Emeljanenko, D.A.Kozlitin, V.I.Machnenko, s.I.Medovar, Ju.~.Sterenbogen.
"Investigation of Temperature Fields of Large Electroslag Remelted Ingo-ts by the Methods of Mathematical Simulation"
in "Special Electro-Metallurgy", Part 1 - Reports of the International Symposium on Special Electrometallurgy, Kiev, June 1972, Naukova Dumka Publishers, Kiev, 1972, pp.l44-154).

In determining the moment for contacting the cooled body 8 with the molten metal, both the demands placed upon the quality of the ingot produced and the economical efficiency, technical feas~bility, and safety o~ the ingot making process are taken into consideration. On the one hand, to obtain ' 20 a sound inyot metal structure, as well as for simplicity of ; construction and safety of the melting operation, it is I preferable that the cooled body be immersed into the molten I metal at an early a stage o~ the ingot making process as possible, while on the other hand, since the presence of a cooled body in the slag bath inevitably calls for an increase in power consumption to ; 35 ' - 15 -~ .. .
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compensate for the heat losses caused thereby, it is advis-able to contact the cooled body with the molten metal at the latest stage of the process possible.

The governing factor in deciding this point is that the angle between the direction of crystal growth and a vertical line must not exceed 45. This is a prerequisite for pro-ducing a high quality ingot, since exceeding this angle causes such a defect of ingot macrostructure as entrapment of non-metallic inclusions between the crystals in the ingot central zone.

The depth of -the immersion of the cooled body 8 into the metal bath 6 is based on the following considerations:
A too deep immersion of the cooled body 8 into the metal bath 6 causes crystals growing towards the bot-tom oE the metal bath 6 to start forming on the cooled body surace.
Intergrowth o these with the crystals growing from the bottom of the metal bath 6 may give rise to such defects as cavities and non-metallic inclusions, in the centre portion ;~
of the ingot.

To avoid such undesirable effects, the cooled body 8 is immersed into the metal bath 6 for not more than 60% of the initial depth of the bath, i.e. of its depth immediately before the immersion. This condition ensures that the crystals emerging on the surface o the cooled body as it con-- _ 16 ,.. ... .

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tacts the metal bath 6 melt down in a shorter time than that needed for their intergro~th with the crystals growing from the bottom of the metal bath 6.

According to another embodiment of the invention, the cooled body 8 is immersed into the metal bath 6 till it ;
momen~arily thrusts against the bath bottom and is then lifted to the predetermined depth, which also must not exceed 60% of the lnitial metal bath depth, at a speed greatly exceeding the melting rate. This technique enables the depth of bath 6 immediately at the moment of immersing the cooled body 8 during the melting operation to be determined, eliminating at the same time the possibility of the above-described effects associated with a location of the cooled body 8 close to the bottom of the metal bath 6.

The cooled body 8 is maintained in contact with the molten metal till the melting operation is complete by moving the cooled body 8 upwardly at a speed close to the melting rate, following which the cooled body is extracted from the bath 6.

The cooled body 8 is generally moved at a speed equal to the melting rate, but modifications with either a higher or a lower speed are possible in principle.

The difference between the speed of movement of the cooled body 8 and the melting rate is restricted by the con-35~

dition that the position occupied by this body in the metal bath 6 must lie between the bath. surface and the critical depth whereat the above-mentioned intergrowth of oppositely growing crystals takes place.
It is reasonable to expect that the optimum action upon the bottom profile of the metal bath 6 would be exerted by -~
the cooled body 8 progressively moved in the course of the melting operation period from the metal bath surface to the maximum possible immersion depth, for which pur.pose the speed of moving the cooled body upwardly would have to be selected less than the melting rate. By appropriately varying the ratio between the melting rate and the speed of the cooled body it will be possible -to provide for a stable bottom profile and for a stable depth of the metal bath 6 during the whole me-l.ting operation. This modification of the method accord.iny to the invention, however, is difficult to achieve at present because the behaviour of the solidi-fied front in the ingot in the presence of a cooled body inside the metal bath depends upon a great many factors, and extensive theoretical and experimental efforts are needed to predict the behaviour.

The simplest for engineering feasability, as will be demonstrated hereinafter by way of two electroslag remelting apparatus for producing ingots, has proved to be tthe above-described modification of the method according to the inven-,¢~

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tion, including immersing a cooled body in the metal bath and subsequent movement of the cooled body at a speed equal to the melting rate.

Fig. 2 illustrates an electroslag remelting apparatus for producing ingots, comprising a mould 2 which is movable and has walls 9 defining an inner space open at the top and bottom ends of the mould, a bottom plate 3 adjoining the bottom end of -the mould 2 when the lat-ter is in its lower-most position and forming therewith a melting container 1 an electrode holder 10 adapted to hold consumable electrodes 5 and disposed above the melting container 1, and a cooled body 8 in the form of a float 11.

The apparatus includes two lifting devices 12 and 13 mounted on a vertical column 14 installed close to the melt-ing container 1.

The lifting devices 12 and 13 are adapted to move the mould 2 and the electrode holder 10, respectively, during the melting operation and are in the form of carriages 15 and 16 mounted for axial movement on the vertical column 14 and provided with drives 17 and 18. The carriage 15 carries the mould 2, and the carriage 16 disposed above the carriage 15 carries the electrode holder 10.

The bot-tom plate 3 of the melting container 1 is mounted on a truck 19 for removing a finished ingot on comple-! 30 :, '~it-.~r s~

tion of the meltin~ operation. The cross-sectional configura- -tion of the float 11 is similar to that defined by walls 9 in the cross-section of the mould 2.

The float 11 has at its bottom a pointed tip 20 to bear against the bottom plate 3 at the initial moment of the melting operation. An enclosed inner space 21 in the float 11 communicates through pipes 22 with a cooling fluid feed system (not shown~
The float 11 is carried by a two-arm lever 23 disposed above the mould 2. A pivot pin 24 of the lever 23 is fi-tted in a yoke 25 attached to the mould 2 on the outside so that a first arm 26 of the lever is disposed substantially in the zone over the mould 2, and a second arm 27, beyoncl this zone.

The float ll,suspended on a hinye pin 29 from an end of the first arm 26 of -the:lever 23 by a bar 2~ rigidly secured to the float,is arranged on the vertical axis of symmetry of the melting container 1. The second arm 27 of the lever 23 carries a counterweight 30 movable along the arm 27 and fixed in the required position thereon by a screw 31 in a threaded hole in the coun-terweight 30 and thrusting against the body of the arm 27. Inasmuch as the mould 2 is operatively connected with the lifting device 12, connection of the pivot pin 24 of~the lever 23 ., .~, .

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to the mould 2 provides for linking the float 11 to the same lifting device 12, which ~s necessary to remove the float 11 from the ingot metal bath on completing the melting operation.

The wall 9 of the mould 2 accommodates a liquid metal level detector 32 electricall~ connected with the drive 17 of the carriage 15 of the lifting device 12 so as -to control the movement of the mould 2. The detector 32 is disposed at a height R from the bottom plate 3, which height is hereinafter referred to as the level of the detector location.
The height a is shown from the lower end of the mould 2.

Before the melting operation is started, the float 11 bears against the bottom plate 3 at the tip 20 under the ;' action of the float gravity.

The float gravity is to be understood as a force acting vertically down the axis of symmetry of -the float, which force in the modification under consideration is conditioned by the difference of the moments of the weight of the float 11 and of the weight of the counterweight 30 with respect to the pivot pin 24 of the lever 23. The difference must be greater than the weight of the molten slag having a volume equal to that of the float 11, but less than the weight of the molten metal having the same volume. The above condition is required for the float 11 to sink in the molten slag, ~ut to be kept afloat in the molten metal.

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On establishing the slag bath 4, the ends of the consum-able electrodes 5 are lowered thereinto, and the melting operation is started. The molten metal accumulates on the bottom plate 3 to form the metal bath 6. As soon as the buoyancy force created by the molten metal exceeds the weight of the float 11, the latter floats up. The depth of float immersion in the floating state is pre-adjusted by shifting the counterweight 30 along the arm 27 of the lever 23. As the molten metal level in the melting container 1 rises, the float 11 moves together with the metal bath 6.
When the bath surface reaches the level Q of the liquid metal level detector 32, the latter actuates the drive 17 of the carriage 15, and the mould 2 starts moving upwardly carrying therewith the lever 23 wlth the float 11. After the melting operation has been completed, the carriage 15 with the mould 2 continues Eor some time moving at a speed equal to the melting rate kill the moment when the mould 2 comes outside the fully solidi.fied ingot. I'he float 11 moving ahead of the b.ottom end of the mould leaves the metal bath before the latter has time to cool down. When changing over from making ingots of one chemical composition to making those of another chemical composition, as well as when changing the melting operation conditions, the depth h of immersion of th.e float 11 can be readjusted by the counterweight 30.

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The above-described construction of the electroslag remelting apparatus for produci:n~ an ingot, comprising a cooled body i;n the form of a float does not represent the only possible embodiment of the invention.

It is to be noted that said principle is also applicable to large apparatus with a stationary mould. A lifting device operatively connected with the float at the final stage of the melting operation should be specially provided for the lQ purpose of removing the float out of the metal bath in this case. Individual units of the apparatus may be variously otherwise constructed. For example, the float gravity may be adjusted by the use of removable elements provided on its body. The coupling of the float to the melting container may take the form of guides restricting its transverse move-ments, while the coupling to the lifting device may be accornpl.ished by means of catchers prov.ided for the purpose.
Other rnod:ifications based on cornbinations of devices kno~n in the art are also possible.
Fig. 3 illustrates another electroslag remelting appara-tus for producing ingots which accomplishes the above-de-scribed method. It differs from the apparatus of Fig. 2 in the construction of the cooled body 8 which is here in the form of an extension 33 fixedly connected to the mould 2 by supporting members 34 resting on the top end of the - . :

- i . :: ~, mould 2. The extension 33 is disposed on the vertical axis of symmetry of the meltin~ container 1. The extension length measured from the top end o~ the mould 2 is less than the height of the mould 2. The extension widens at the bottom.
Its intermediate portion 37 disposed between its narrow portion 35 and wide portion 36 connects both said portions 35 and 36 and is shaped similar to a cone. The wide portion 36 of the extension 33 is arranged below th~ level ~ of the liquid metal le~el detector 32 over the bottom plate 3.
Inasmuch as the dimension a predetermines the liquid metal level at which the cooled body 8 becomes irnmersed to the specified depth h, it must be selected proceeding from the above-mentioned considerations that the metal bath bottom profile at the central portion of the bath should have no sections inclined to a horizontal line at an angle exceeding 45. ~s indicated above, the level is determined by calcu-lation or experimentally and depends on -the size and chernical composition of the ingot to be produced and on the melting operation conditions.
In the same manner the height h of the wide portion 36 of the extension 33 is -found, which height should not exceed 60~ of the depth of the metal bath 6 when the liquid metal level in the melting container 1 corresponds to the level Q
of the detector 32.

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The cooled body 8 in the apparatus shown in Fig. 3 is a hollow cast~ng whose internal space communicates with a cooling system ~not shown~. other modifications of the cooled body are also possible, some of which are shown in Figs. 4-9 of the drawings.

The extension 33 of the cooled body 8 may take the form of a pipe grating as shown in Fig. 4. Figs. 5-9 illustrate the extension 33 in the form of a coil of different config-urations: a helical coil (Fig. 5); a flat vertical loopemployed for a rectangular mould whose narrow face width is not over 500 mm (Figs. 6, 7); and a loop having a horizontal portion 38 wherein the bent pipe forms a nearly complete circle (Figs. 8, 9).
The la-tter modification is applicable to a circular cro.ss-section mould. ~s shown in Fig. 8, the hori~ontal plane ~ of symmetry of the loop portion 38 lies at the level a f the liquid metal level detector 32. The p]ane may also lie somewhat above said level, but not below the latter to avoid freezing of the extension 33 to the crystallizing metal of the ingot. Vertical portions of the loop, inlet one 39 and outlet one 40, are disposed symmetrically with respect to the vertical axis of symmetry of the melting container 1.

The apparatus functions as follows.

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When electric current is fed to the consumable elec-trodes 5 (Fig. 3I lo~ered into the slag bath 4, molten metal rrom their ends flow into the melting container 1, forming the metal bath 6.
Rising during the melting operation, the molten metal of the metal bath 6 contacts the cooled body extension 33 at first only by the surface of the metal bath 6 and then grad-ually reaches the level a at which the depth of immersion of the extension 33 equals the specified depth h. At this moment, on a signal from the detector 32, the lifting device 12 starts lifting the mould 2 and the cooled body 8. Inas- ;
much as the lift proceeds at a speed equal to the melting rate, tKe depth h of immersion of the extension 33 of the cooled body 8 remains constant over the entire melting operation period. On completion of -the melting operation, when khe ingot 7 has reached the specified height, the mould 2 with the cooled body 8 still continues moving at the same speed till the mould 2 comes fully outside the height of the solidified ingot. Being shorter than the mould 2, the extension 33 of the cooled body 8 leaves the metal bath 6 before the latter cools down.

The above-disclosed apparatus is simple in construction and may find application in producing large solid-section ingots for which the above-described production technique has been developed well enough and no correction of the posi-.. ,;
...... .

tio~ o~ ~he detec~or 32 a~d o~ the cooled body 8 in th~ :~
mould 2 is ~eededO
It is quite evident to those 3killed i~ the art t~a~
the inventlon i~ ~o~ limited to the above disclo~ed electro- .
~lag remelting apparatus ~or produci~g a~ i~got a~d ~hat ~ d~
departures ma~ be/thexe~rom i~ accomplishi~ th~ method o~
the inve~tio~.
For a ~uller u~derstanding o~ the ~ature o~ ~he i~en-~io~, ~pecific e~amples o~ a¢complishi~g the m~thod o~ thei~ve~tion are prese~tqd below.
Example 1 A 1100-mm-diamoter, 2300-~m high cyli~drical ingot of ateel co~taining about 0.2~o car~o~ was produced. '~he mel~i~g rate in tsrms of wcight wa~ con~t~nt a~d amounted to about 1000 kg/h which correspo~ded to a li~ear speed o~ V _ 435 mm~hQ
'Nhe~ the molten metal level had reached 300 mm, a cooled body was i~troduced i~to the met~l bath to a depth of 50 mm which amou~ted to 2G% o~ the bath depth, At the mome~t of i~t~oductio~ the gre~be~t angle o~ incli~ation to ~ hori~
zo~bal li~e o~ the bath bottQm profile i~ the ce~-t~al portlon wi~hin a diameter o~ 8~5 mm ~a~ 28.
The bottom profile a~d the metal bath depth have been both here and herei~after determi~ed from the graphs in ~ig. 10 represe~ti~g ~he li~uidus isotherm~ for di~fere~t .. . .

~ 27 -., , ,, .. ... , , ., ... , . .... . ... ... .. . ., . .. ... . . . - -.. . . . . .
, ~ ~ .
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, 35~

moment~ o~ the meltin~ operatio~ i~ maki~ an i~ot o~ a defi~ite size and shapeO ~he i~otheIms correspo~d to the ::
melting operatio~ co~ducted without i~troduci~g a cooled body a~d have been calculated ~ith the k~ow~ procedure (~ee the c~bove-me~tio~ed re~ere~ce to a report in "Special :~
~lectro-Metallurgy"~ Part 1). ~he numeral~ at the ab~cissa axis o~ each ~raph denote the i~got radiu~ and at the ordi-d1'~nc, or1s B nate axi~ the i~got height (The ~ ~ are i~ cm.
l~hs data ~or the example bei~g reported have bee~ take~
~rom the graph i~ Fig. 10a. The cooled body who~e portion ~s brought i~to co~tact with the molten metal had the form o~
a tru~cated co~e co~ve~gin~ dow~wardly and m0a~uri~g dia.
300 :~ dia,500 x 350 mm wa~ after immer~io~ moved upwardl~
at a speed equal to the melti~g xate~ When the molte~ rQetal leve~ had reached 2300 mm9 the cooled body wa~3 rapidly xemoved out o~ the metal bath.
~ he template prepa~ad ~rom the producsd i~got e~{hibited a~ ordere~ e-~;rai~ed~ compact m~tal structux~ ~7ith ~o ~L s~ l~c~A ~ r ~hrinkage deI~ct~. ~he ~ ~ print o~ ~he mul-ten metal bath bottom ha~ a ~ro~ou~ced E~rotubera~ce i~ the central portio~, Exar~ple 2 I~ making an i~got oî th~ ~ame ~i~e a~d compositio~ a~;
tho~e in Example '1, the cooled bod;y (t}~ same as l~ Example1) was immer~ed irrto the molte~ metal to a depth o~ '168 ~ ~Jhich ~8 "

,. ,, " ,. - ;.

5g~3 co:~;tituted ~0~70 o~ the me-tal bath depth at the Dlomellt ~I~J
Ghe maxim~un angle o~ inclinatio~ ~o a ~Lorir~.onlial l.ine o1~ the bath bottor~ proIile i:n the cen-Gral portio~ was 45~ d t~e liquid metal level i:~ the ~elti~3g co~tairLer wa~ 800 mm, (~ee l~ 10a) 0 B 'l~he ~ cooled body wa5 li~ted at a ~p~ed equal -.,o the meltl~g rate a~cl was rapidly ~emoved out o~ ~he metal ba~h o~ compleGio~ o~ ~he melting o~erationO ~o di~co~.,ir~uiGi~s in ~:
the metal s~ructure in the i~;ot c~tral poIGion were i`ound~ :~
Ez~ample ~ -'l'he ingot a~d the melti~g o~e~atio~ co~ditions ~iere Jh~
same a~ in ~xamples 1 and ~. 'l'he cooied bo~ the same a~ in tho abov~ ~xa~ple~ wa~ imm~ræ~d into the metal bath ~'or a depth of 246 ~n which co~stituted 6~/~ of the bath depth at the moment whe~ the ii~uid metal le~el i~ the meltlng co~- ~
tainer ~as 800 mm a~d the ~a~imum angle o~ î~clinatio~ to a ~ `
hori~ontal li~e of the ~etal bath bottom pro~ile i~ the ce~tral po~tio~ o~ the bath wa~ ~r5 (se~ , 10a)0 ~he~ the cooled bod~ wa~ ted at a ~peed e~ual to the mel'ci~ rat~ and wa~ ~apidl~ removed out o~ the metal bath o~ completio~ of the melti~g operabion~
Small de~lectio~ ~rom the commo~ dire¢tio~ o~ cx~J~al ~rowth we:ce obser~ed in the i.Qgot central zo~O ~o segregation and ~hrink~ge defects were found4 ~' `
~ ' - 29 - :
.
';

.

~, 55~
Example 4 The ingot, the melting operation conditions, and the cooled body were the same as in Examples 1-3. The cooled hody was immersed into the metal bath to a depth of 275 mm which constituted 65~ of the ~ath depth at the moment when the liquid metal level in the melting container was 800 mm and the maximum angle of inclination to a horizontal line of the metal bath bottom profile in the central portion of ; 10 the bath was 45 (see Fig. lOa).
.
I Then the cooled body was lifted at a speed equal to the : melting rate and was rapidly removed out of the metal bath on completion of the melting operation.
The ingot structure in the central portion was inhomo-yeneous, crystal yrowth was di.sordered, there were zones with oppositely directed crystallization, shrinkage deects, I aggregations of non-metallic inclusions.
~ Example 5 ! The ingot, the melting operation conditions, and the cooled body were the same as in Examples 1-4. The cooled body was immersed into the metal bath to a depth of 275 mm which consti.-tuted 40% of the bath depth at the moment when the liquid metal level in the melting container was 1420 mm and the maximum angle of inclination to a horizontal line of the metal bath bottom profile in the central portion of the bath was 55 (see Fig. lOa).

:
: 35 .: . .

35~

~ 'he-.-thc~i cooled bo~y was li~ted at a spead equal to the mell;i.~g rate and was rapidly removed out o:e ~ha metal bath on com~l~tion o~` the mel~inO oparatio~O
~ he i~got structure in the ce~-tral ~)ortion was loose9 and a~re~atio~s o~ ~}~e inclusLorls were ~oundv ~xample &
'~he ingot and the meltin~ op~ra-tion co~ditio~s we:re ~he sama as in ~xample~ 1-5, '~Ihe malti~c~ o~eratio~ was co~ducted in tha apparatus shown in ~ig, 20 'l'he ma~imum diarnster o~ :
tha ~loa~ 11 was ~00 mrn. At the initial mome~t OL the ~elti~O
ope~tion~ the tip 20 of th~ ~loat ~1 bore a~ai~st the bottom ~late ~. When th~ ligui(l metal level had re~chod ~0~
th~ ~'loat 11 ~'loated up and the depth of' its i~nersion into the metal bath amounted to 100 mm which corre~pond~d to 50~o of the bath dep-th. On comple~ion o~ the melting opera- -tion, the lif`ting device 12 lif`ted the ~loat 1~ above the liquid metal le~el.
~ he metal structure in the ingot ce~ral portlon was oràered9 ~i~e-grai~d~ compact, with ~o snrinkaOe dsfect~
The bath bottom had a ~ro~ub~rance in tho contral poxtio~, ~ample 7 A 2700-mm-diametor~ 4430-mr~-high c~li~drical in~ot of 200 t i~ wei~ht o~ ~teel co~taini~g about 0~2Yo carbon was :
'- .

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produced in an apparatus OL the type sho-vn i~ ~`ig. ~7 wherei~
the extension j3 of the cooled bo~y 8 had the ~orm. o~ a : pipe grating.~ a~ sho~ ig. 4. '~he ~elti~æ rate i~ terms o~ weight vJas co~stant and amou~ted to 2700 ~g/h which corres~ ~;
pon~ed to a linear ~peed o~ about 60 m~Jh~ 'L~he li~uid me~al leval detec-tor 32 was i~stalled at a level of ~ = 1200 from the bottom plate 3. ~he wide portion 36 OI the e~te~slon had the form o~ a spherical seg~e~t with a ~adiu~ oE' curvacu- ;
re o~ 2400 mmO The diameter o~ the portion was 1900 ~ a~d the height ~60 mm 9 which conditio~ed immersio~ of tn~
cooled bod~ 8 a~ the moment when the sur~ace o~ tho me~al bath 6 had roached a level o~' 1200 ~m to a depbh o~ ~ ~360 conel~tubing 60~ of the metal ba~h ~al~th co~resQor~ to ~aid level i~ a~ in~ot of' the same size produced w1thout introduci~g a cooled bod~ (see ~ig. 10b).
The maximu~L a~gle o:E incliIlatio~ ~o a horizontal li~e OI
the bottom pro~ile of' the metal bath 6 in it~ central portio~
within ~ diameter o~ 2025 rnm wa~; 35 at said mome3::t~
On completion o~ the malti~s operatio~, movi~g thv mould 2 a~d the cooleA bodg 8 at a speed equal GO the melti~g rai-,e continued u~il the mould 2 wa~ removed out~ide tha hei~h-t of the i~otO
~'he ternplate preparad ;erom the ~ oduced ingot exhibited a compact9 ~i~e-~rained, orderad metal structure with no segrega~ion a~d shrinka~e de~ects. The metal ba~h bottom in B the i~;ot ce~tral portiorl was ~3r~ped as a e~ ~u~al~, -? - 32 ~

;. . ... ~.... " ,, , ~ :

s~

~3xample A 250 x 1100-mm-sectio~, 1500-mm-hi~h rec-ta~ular in~o~
of 4 t in weight of steel contai~i~ about 0,2~o carbo~ was produced in a~ apparatus o~ the type shown in ~ig. 3 with the cooled bo~y 8 o~ the ~orm shown i~ ~igr 70 r~he ~elti~c3 rate in terms of weight was consta~t a~d amou~ted to 1~30 k~/h which correspo~ded to a li~ear speed of about soa mm/h~ :-~ he llquid metal level detector 32 was i~tall~d at a height Q = 200 mm from the bottom plate 3. ~he maximumsi~e o~' the ex*ensio~ 33 of the cooled body 8 at the wide portion was ~00 mm measured i~ parallel to a wide f'ace o~ the mould)0 ,.
'rhe hei~ht h ox the wide poxtion ~6 o~' the e~t~s1oll ~3 was ~0 ~m, which co~dibio~ed i~mexsion of' the cooled bod~
at the moment when the surface of the metal bath 6 had reached a level o~ 200 mm to a de~?th o~ h = go mm co~stitu- :
ting 60!7'o of the metal bath depth correspo~ding to said lev~
i~L a~ i~got (oî the ~ame size produced withou~ immersing a , rl C IJI,~ 4t 1 ~
B cooled body (see ~i~;. 10c),, '~he maximum a~le o~` inli~o~
to a horizo~tal li~e o~ the bottom pro~ile o.~ the bath in its ce~tral por-tion (within an area measuri~g 1~8 x 825 ~m) was 45 at said moment~ .
On completion of the melting op~ration, movi~g bhe mould 2 ~nd the cooled bod~ 8 at a speed e~ual to the melti~g rate co~ ued until the mould ~ was removed outside the i~got.
'l`he i~y;o.t ~as cut alon~; the ~7ertical axis o:e symmetry of tha wide ~ace .

- ~3 -.. .- ~

.. . , . : ~

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il'he metal sGructure ~Nas ~ e-~rai~edg compact~ oI~der~d with rlo ~isconti~ulties~
'~`he abo~e-disclosed metr~od and apl,axatus ~or producing soiid-section in~ots b~ electroslag remelti~g e~suxe a -:
high quality OI' the -oroduced i~gots 9 being at tha same -~ime simple~ and more economicall~ e~Iicie~t than the ..~rior axt me~hods a~ apparatus OL t~e same purpose ~hich allow obt~
the ~etal o~ the same ~uality as a resul~ o~ a co~xolled actio~ upo~ the ingot cr~stallizatio~ processO
Whil~ pa-rticular embodim~ts of th~ entio~ have bee~
shown and described, various modif'ications thexeof' will be a~pare~t to those skilled i~ th0 art. V~rious other mo'ifica-tio~s ma~ also bo ~llade ln th~ inve~tio~ without departing f'rom th~ spirit and scope t:hereo~ as de~i~ed in the claim~

~:

Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLU-SIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1, A method for producing a solid-section ingot by electroslag remelting, including remelting at least one con-sumable metal electrode in a slag bath in a melting container to form in said container a molten metal bath progressively crystallizing into an ingot so that the interface between the crystallized metal and the molten metal constituting the metal bath forms the bottom of the bath, the slag-metal bath inter-face moving upwardly as the molten metal is fed into the melting container; bringing a cooled body into contact with the molten metal constituting the metal bath so that said cooled body is disposed on the vertical axis of symmetry of said melting con-tainer; maintaining said cooled body in contact with the molten metal till the melting operation is complete by moving said cooled body upwardly at a speed close to a predetermined solidifying rate to avoid contact with the crystallized metal;
and removing said cooled body from the metal bath after the melting operation is complete.

2. A method according to claim 1, wherein said cooled body is brought into contact with the molten metal prior to the moment when sections inclined to a horizontal line at an angle of 45° are formed in the profile of the metal bath bot-tom and when such sections appear within the zone, the trans-verse dimensions thereof on the metal bath surface amount to not less than 75% of said surface; said zone being normally symmetrical with respect to the vertical axis of symmetry of the melting container.

3. A method according to claim 1, wherein said cooled body is immersed into the molten metal bath to a depth not exceeding 60% of the maximum depth of said bath which it had prior to the moment of immersion of said cooled body therein.

.

4. A method according to claim 1, wherein said cooled body is immersed into said molten metal bath till it momentarily thrusts against the bath bottom and thereafter said cooled body is moved upwardly at a speed exceeding the melting rate to the predetermined level, whereat the depth of immersion of said cooled body into the metal bath does not exceed 60%
of the maximum depth of the metal bath which it had prior to the moment of immersion, of said cooled body therein following which said cooled body is moved upwardly at a speed close to the predetermined solidifying rate.

5. A method according to claim 1, wherein said cooled body is heavier in weight than that of the molten slag displaced by the portion of the cooled body which is immersed into the slag bath when said cooled body is immersed into the metal bath, but lighter in weight than the weight of the molten metal displaced by the portion of the cooled body which is immersed into the metal bath.

6. A method according to claim 1, wherein the cooled body is moved at a speed approximately equal to the melting rate.

7 . An electroslag remelting apparatus for producing a solid-section ingot by remelting at least one consumable metal electrode in a slag bath, comprising: a bottom plate;
an open-ended mold defining an internal space therein and supported on said bottom plate and forming therewith a melting container; a cooled body disposed substantially on the vertical axis of symmetry of said melting container and being a float whose weight is heavier than that of the molten slag having a volume equal to that of the float and lighter than that of the molten metal having the same volume; and a lifing device installed close to said melting containing and connected with said open-ended mold and with said cooled body, which provides for raising the open-ended mold upward during the melting operation and for removing the cooled body from the metal bath when the melting operation is complete.

8. An apparatus according to claim 7, wherein the float is provided by an adjustable counterweight.

9. An apparatus according to claim 8, wherein the float and the counterweight are mounted on opposite ends of a two-arm lever installed above the mold for rocking with res-pect thereto.

10. An electroslag remelting apparatus for producing solid-section ingots by remelting at least one consumable metal electrode in a slag bath, comprising: a bottom plate; a mov-able open-ended mold defining an internal space therein and disposed over said bottom plate for vertical movement and supported in its lowermost position on said bottom plate, form-ing therewith a melting container; a lifting device installed adjacent said melting container and operatively connected with said movable mold; a lever having a first arm, a second arm, and a pivot pin disposed between the first and the second arm, the pivot pin being secured to said mold on the outside thereof so that the first arm is disposed substantially in the zone over the inner space of said mold and the second arm is disposed beyond said zone; a cooled body disposed substantially on the vertical axis of symmetry of said melting container and being a float whose weight is heavier than that of the molten slag having a volume equal to that of the float and lighter than that of the molten metal having the same volume, said float being hinged to the end of the first arm of said lever;
and a counterweight installed on the second arm of said lever and adapted for movement along said lever to adjust the depth of immersion of said float into the metal bath of the ingot being made.

11. An electroslag remelting apparatus for producing a solid-section ingot by remelting at least one consumable metal electrode in a slag bath, comprising; a bottom plate; a mov-able open-ended mold defining an internal space therein and disposed over said bottom plate for vertical movement and supported in its lowermost position on said bottom plate and forming there-with a melting container; a lifting device installed adjacent said melting container and operatively connected with said movable mold; a liquid metal level detector installed in the wall of said movable mold commands wherefrom ensure the con-trolling of the vertical movement of said movable mold in accor-dance with the movement of the slag-metal interface relative to the detector in the course of the melting operation; and a cooled body disposed inside said movable mold on the vertical axis of symmetry of said melting container, said cooled body comprising supporting members secured to the top end face of said movable mold and an extension projecting downwardly from said end face for a length less than the height of said movable mold, the extension of said cooled body including a wide por-tion disposed below the level of said liquid metal level de-tector, a narrow portion disposed above said wide portion, and an intermediate portion whose surface is shaped similar to a cone and connects said narrow and wide portions, thereby providing for flow of molten metal drops down from the surface of said cooled body.

12. An apparatus according to claim 11, wherein the extension of the cooled body is in the form of a grating com-posed of pipes.

13. An apparatus according to claim 11, wherein the extension of the cooled body is in the form of a coil.

14. An apparatus according to claim 13, wherein the coil is a pipe bent in the form of a loop.

15. An apparatus according to claim 14, wherein the pipe bent in the form of a loop has a horizontal portion where said pipe is bent substantially circular and vertical inlet and outlet portions thereof disposed symmetrically with respect to the vertical axis of symmetry of the melting container, the horizontal plane of symmetry of the horizontal portion of the loop being disposed not lower than the level of the liquid metal level detector.

16. An electroslag remelting apparatus for producing a solid-section ingot by remelting at least one consumable metal electrode in a slag bath, comprising: a bottom plate;
an open-ended mold defining an inner space therein and sup-ported on said bottom plate and forming therewith a melting container; a cooled body disposed substantially on the vertical axis of symmetry of said melting container and being a float whose weight is heavier than that of the molten slag having a volume equal to that of the float and lighter than that of the molten metal having the same volume; a lever mounted above said mold for rocking with respect to the latter and having a first arm and a second arm, the first arm of said lever being disposed substantially in the zone over the internal space of said mold and having its end connected with the float, a counterweight operatively associated with said second arm for movement along said lever, and said second arm of said lever being disposed beyond said zone; and a lifting device installed close to said melting container and connected with said open-ended mold and with said cooled body, which provides for raising the open-ended mold upward during the melting operation and for removing the cooled body from the metal bath when the melting operation is complete.

17. An apparatus according to claim 10, wherein said cooled body comprises supporting members secured to the top end face of said movable mold, and an extension projecting downwardly from said end face for a length less than the height of said movable mold, the extension of said cooled body including a wide portion disposed below the level of said liquid metal level detector, a narrow portion disposed above said wide por-tion, and an intermediate portion whose surface is shaped similar to a cone, and connects said narrow and wide portions, thereby providing for flow of molten metal drops down from the surface of said cooled body.