Horizontal continuous casting of steel

ISSN 09670912, Steel in Translation, 2010, Vol. 40, No. 1, pp. 3846. Allerton Press, Inc., 2010.Original Russian Text M.N. Popkov, V.V. Reshetov, A.I. Trushin, 2010, published in Stal, 2010, No. 1, pp. 2432.

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Research into the horizontal continuous casting ofmetal began in the first half of the nineteenth century,when Lining (USA) was awarded a patent for a systemused in the production of lead pipe [1]. This was probably the first patent relating to continuous casting,according to [2].

The industrial introduction of horizontal machinesbegan with the casting of nonferrous metals and hotmetal, which presented no particular difficulty sincethe molds could be made from materials whose melting point exceeded that of the alloys being cast. By themidtwentieth century, the horizontal continuouscasting of metals was widely employed.

However, casting methods for nonferrous alloys areinapplicable for steel, on account of its high meltingpoint, its aggressiveness with respect to refractories,and the higher productivity required. At the sametime, the development of horizontal continuous casting of steel was attractive on account of benefits of horizontal casting such as the low height of the equipment, the protection of the liquid steel from secondaryoxidation by sealing of the joints between the metalintake system and the mold, and the lack of deformation of the solidifying billet.

At present, more than 40 horizontal machines areoperating around the world; this accounts for less than1% of the total number of casting machines (in termsof the number of strands) [3]. At the same time,around 2530% of the patents for the continuouscasting of steel relate to horizontal machines [4].

The first horizontal machine for casting steel billetabout which we have information was patented byJacques (Belgium) [1]. It was intended for the production of six strands corresponding to billet of cross section 100 100 and 150 150 mm. Experiments on theJacques machine continued from 1943 to 1954 butproved unsuccessful, since there was no provision forperiodic billet extension or rocking of the mold.

Abroad, horizontal continuous casting underwentits greatest development at the end of the 1960s,

thanks to work by Davy Loewy (later DavyAshmore,Britain) and General Motors (United States) [5]. Successful designs for a reliable joint between the metalintake and the mold were proposed. These firmsemployed separating rings of silicon nitride or boronnitride to ensure satisfactory initial shaping of theingot casing and, correspondingly, stability of the casting process.

Operation of the DavyAshmore experimentalmachine proved very successful. This machine permitted the casting of steel from a 0.5t ladle as billet with adiameter of 100 mm or a cross section of 100 100 mm.Subsequently, the machine was reconstructed in semiindustrial form (Fig. 1). In 1972, it was installed in thesteelcasting shop of the Davy Roll plant (Jarrow,England), to produce billet with a diameter of 75150 mm or a cross section of 95 95 mm from carbon,lowalloy, alloy, highalloy, chromonickel, and bearingsteel [6]. Besides refinement of the design for the jointbetween the metal intake and the mold, it was established during the operation of this machine that, withperiodic extension at a rate of 5560 min1, the billetsurface is satisfactory for subsequent rolling. The casting time from a 6t ladle was 1 h.

On the General Motors machine installed at theOldsmobile plant in Lansing (United States), billetwith a diameter of 96 mm for autoindustry forgingswas obtained. This was the beginning of the industrialintroduction of horizontal continuous casting of steel

Horizontal Continuous Casting of SteelM. N. Popkov, V. V. Reshetov, and A. I. Trushin

OOO Spetsmash, Moscow, Russia

AbstractThe history of horizontal casting of steel is considered. Some features of horizontal machines arenoted: low height; no ingot deformation in casting; no secondary oxidation of the metal; the ability to castsmall cross sections. The basic characteristics of Russian systems are described, along with operational experience. The prospects for horizontal machines in metallurgical micro mills and in the reconstruction of existing mills are discussed.

DOI: 10.3103/S0967091210010109

1 2 3 4 5 6

Fig. 1. DavyAshmore semiindustrial horizontal continuouscasting machine [6]: (1) intermediate ladle; (2) mold;(3) secondarycooling zone; (4) extension unit; (5) screwmechanism; (6) exit roller conveyer.

STEEL IN TRANSLATION Vol. 40 No. 1 2010

HORIZONTAL CONTINUOUS CASTING OF STEEL 39

outside the Soviet Union. Horizontal castingmachines were also produced by Technica Guss,Bhler, Krupp (Germany), SKE (United States),VstAlpine (Austria), Kobe Seikose (Japan), andother firms. By 1983, 30 horizontal machines were inoperation outside the Soviet Union [7]. In that period,the basic concept that horizontal machines are bestused in casting highquality steel was developed.

In Soviet metallurgy, work on the horizontal continuous casting of steel began with the construction ofan inclined conveyertype continuouscastingmachine in 1946 (the Goldobin machine), shown inFig. 2 [8]. The mold in this machine consisted of tworows of halfmolds attached to two conveyer belts. Theingot was formed in the cavities between the halfmolds and moved without slip of the housing relativeto the mold. This horizontalcasting method was notwidely adopted, on account of the leakage of steel intothe joints between the molds, which impaired billet lifeand quality. Nevertheless, billet of cross section from100 100 to 150 150 mm was cast from a 40t ladleat speeds up to 5 m/min on the Goldobin machine.The acceptance rate of the billet was 90%.

Subsequently, research on the horizontal continuous casting of steel continued at the Ukrainian ScientificResearch Institute of Metals (Kharkov), the AllUnion ScientificResearch Institute of MetallurgicalMachinery (Moscow), Tulachermet Scientific Production Center, the Central ScientificResearch Institute of Ferrous Metals (Moscow), the AllUnionInstitute of Aviation Materials (Moscow), and Uralmash Production Center (Sverdlovsk).

In 1960, an experimental horizontal machine forthe production of round (80200 mm), square (130 130 mm), and rectangular (75 500 mm) billet wasbuilt at the Ukrainian ScientificResearch Institute ofMetals (Fig. 3) [9]. The steel was cast from a 1.0t arcfurnace by means of continuous ingot extension androcking of the metal intake with the mold. Numerousexperiments provided information on the temperatureof the liquid metal, the solidifying ingot, and the moldduring casting, the solidification parameters of theblank in different cross sections, and the surface quality and internal structure of the metal as a function ofthe casting conditions. Various junctions of the graphitefireclay supply nozzle with the mold were tested:for round billet, sleeves with and without a collar at thejunction point; for square and rectangular billet, insertion into a hole in the end wall.

Experimental trials of the horizontal machine atthe Ukrainian ScientificResearch Institute of Metalspermitted the development and construction of a twostrand experimental industrial system at TulachermetScientific Production Center in 1974 (Fig. 4) [10].This was the first use of modular molds with drilledcooling channels and subsequently with a thinwalledsleeve developed at the AllUnion ScientificResearchInstitute of Metallurgical Machinery. A graphitefire

clay nozzle with a special coating was used at the junction of the metal intake and the mold. Secondary cooling of the billet beyond the molds was ensured by aforced roller system. Each strand was provided with anindependent extension mechanism; its hydraulic driveensured periodic extraction of the blank from the moldin joltpause mode, by means of shaped shoes. Theperiodicextension increment was 2050 mm; the frequency was 2040 min1. Carbon and lowalloy steel

12 3

4

Fig. 2. Goldobin machine [8]: (1) basic ladle; (2) intermediate ladle; (3) dosing unit; (4) mold.

12

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Fig. 3. Experimental horizontal continuouscastingmachine at the Ukrainian ScientificResearch Institute ofMetals [9]: (1) metal intake; (2) mold; (3) extension cell;(4) seeding unit.

567 1234

Fig. 4. Horizontal continuouscasting machine at Tulachermet Scientific Production Center [10]: (1) metalintake; (2) mold; (3) secondarycooling zone; (4) extensionunit; (5) gas cutter; (6) dummy bar; (7) offloading system.

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was cast. In rolling billet with tenfold extension, theproperties of the product satisfied State StandardGOST 1050.

The characteristics of the horizontal machine at Tulachermet Scientific Production Center are as follows:

A gas cutter is used to chop the rolled steel intomeasured lengths.

Operational experience with the machine at Tulachermet Scientific Production Center provided thebasis for the Soviet technology used in horizontal continuous casting of steel. For example, the horizontalmachine acquired a small inclination of the technological axis (57), so as to ensure high productivityeven when casting individual melts, with only slightincrease in height of the equipment. The possibility ofcasting highquality square billet in a mold with a circular input hole was demonstrated. In casting individual melts, it proved possible to use graphitefireclaysupply nozzles rather than ceramic nitride nozzles inconnecting the metal intake with the mold.

The most significant finding from the operation ofthat machine was the efficiency of horizontalmachines in casting not only alloy and highalloy steel

Billet cross section, mm Diameter 130, 80 80120 120

Number of strands 2

Ladle capacity, t 10

Number of metal intakes 1

Metalintake capacity, t 2

Inclination of technological axis, deg

7

Billetextension mechanism Hydraulic

Mean casting speed, m/min 0.42.0

Rated power, kV A 150

Length; width; height, m 24; 10.5; 5.1

Mass of equipment, t 85

but also regular carbon steel. Note that this changedthe opinion of numerous foreign specialists regardingthe composition of cast steel. It became obvious thatthe horizontal method is effective in highvolumecasting of steel (including carbon steel). A major benefit of this process is the considerable reduction incapital expenditures [11].

In 1966, research on the horizontal continuouscasting of steel began at the AllUnion ScientificResearch Institute of Metallurgical Machinery. Anexperimental machine for the production of round,square, and rectangular billet from steel of a range ofcompositions was constructed at the Institute (Fig. 5).Carbon, alloy, and highalloy steel was cast, as well asnickel alloys smelted in a 1.5t arc furnace.

The characteristics of the horizontal machine atthe AllUnion ScientificResearch Institute of Metallurgical Machinery are as follows:

The molds (modular or detachable with drilled cooling channels) and metal intake may perform reciprocating motion on a common frame, but rocking of themold with a motionless metal intake and supply nozzleis also possible. The path of the reciprocating motion is380 mm; the frequency is 2080 min1. In addition,the machine is equipped with a device for periodicextension of the billet in joltpause mode by automaticopening and closing of the rollers in the extension cell.Beyond the mold, there is a zone of secondary screenedcontact cooling or forced cooling.

In the experiments, most attention was paid to thejunction of the metal intake with the mold and theinfluence of the refractory configuration in the moldand the extension conditions on the surface quality ofthe billet. Various junction configurations were considered: end to end (Fig. 6a); with insertion of themetal line in a simple mold (Fig. 6b) or a mold with acollar (Fig. 6c). A metal line consisting of a refractorynozzle in a watercooled copper disk (a seal) was alsoemployed, to permit rocking of the mold with amotionless metal line (Fig. 6d). To compensate for theheat losses from the liquid metal on moving through

Billet cross section, mm Diameter 120150, 120 120140 140

Number of strands 1

Metalintake capacity, t 0.3

Length of mold, mm 840

Billetextension mechanism Fourroller extension cell with electric drive

Mean casting speed, m/min 0.26.0

Dimensions, m:

overall length 29

working length 9

height 2


Fig. 5. Experimental horizontal continuous castingmachine at the AllUnion ScientificResearch Institute ofMetallurgical Machinery.



the metal line, a highfrequency current inductor wasinstalled on the refractory nozzle (Fig. 6e). Graphitefireclay nozzles were mainly used.

A notable feature of horizontal continuous castingis that the billet exhibits characteristic tracks associated with the periodicity of the process. Consider theformation of the ingot casing in the initial shapingzone (Fig. 7), with billet extension according to thecommonest system: joltinverse passpause. Inextension at constant speed, with rocking of the mold,there is little qualitative change in the process. Thestate of the crust in the initialshaping zone at the endof the pause ( = 0) is shown in Fig. 7a. At the jolt(Fig. 7b), billet is extracted from the mold and beginsto form the crust for the new increment; some is created at the end of the metal line, and some at thedeparting end of the crust from the previous increment. A traveling discontinuity I appears; a junction IIis formed between the crusts in the present and preceding extension increments. At the end of the extension phase when = ex (Fig. 7c), the billet stops; thetwo parts of the new crust coalesce, and a junction ofthe solidification fronts forms at the traveling discontinuity. Then the inverse pass begins (Fig. 7d); duringthis phase, the junction in the solidification fronts ishealed and sealed. At the end of the inverse phase(Fig. 7e), the pause begins; the crust thicknessincreases while the billet is motionless.

The junction of the solidification fronts is notregarded as a surface defect but mainly influences thestrength of the ingot casing that forms. The casingstrength must be sufficient to withstand the frictionalforce of the billet at the mold in the next jolt. The presence of the junction between the increments is moresignificant, since it may impair the surface quality ofthe rolled metal, depending on the design of the junction between the metal line and the mold and also onthe casting parameters.

In experimental casting at the AllUnion ScientificResearch Institute of Metallurgical Machinery,the best results were obtained with the insertion of themetal line in a simple mold or a mold with a collar(Figs. 6b and 6c). It is found that for an extension(rocking) cycle of 4050 min1, the depth of the increment junctions is no more than 1.01.5 mm, whichhas no influence on the rolling of carbon and lowalloysteel billet. This is consistent with the findings for theDavyAshmore experimental horizontal machine.However, for alloy and highalloy steel, the frequencymust be increased to 80 min1 or more. In that case,the junction depth is no more than 0.5 mm. The collarhas no influence on the depth of the increment junctions, which confirms the validity of casting square billet in a mold with a round input. Later, this was notedby NKK (Japan) specialists in experiments on a horizontal machine at Keihin [12].

The microstructure of the billet obtained at the AllUnion ScientificResearch Institute of MetallurgicalMachinery is basically the same as for billet from radialmachines, except that the thermal center of solidification is displaced above the billet axis by 37 mm.

In the 1960s, at the same time as the research at theAllUnion ScientificResearch Institute of Metallurgical Machinery and the Ukrainian ScientificResearch Institute of Metals, a horizontal machine forcasting consumable nickelalloy electrodes in vacuumarc remelting furnaces was produced and putinto operation at the AllUnion Institute of AviationMaterials [13]. For electrodes produced by conventional ingot rolling, the acceptance rate is no morethan 50%. In electrode casting in molds, problemsarise in their extraction after solidification; in remov

1 2 3

4 5

(a) (b) (c)

(d) (e)

Fig. 6. Options for insertion of metal line in mold: (ae) asexplained in text; (1) metal intake; (2) metal line;(3) mold; (4) seal; (5) highfrequency current inductor.

1

2

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I II

vex

(a)

vin

(b)

(c)

(d)

(e)

( = 0)

(0 < < ex)

( = ex)

(ex < < ex + in)

(ex + in < < f)

Fig. 7. Solidification of horizontal continuouscast billetin initial shaping zone: (1) separating ring; (2) mold;(3) ingot crust; (4) liquid metal; vex, extension rate; vin,speed in inverse pass.

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able molds, the electrodes are characterized by flashing and transverse cracks.

In the new technology, the metal was smelted in a200kg induction furnace and poured directly into themetal intake, with no casting ladle. A modular moldand a graphite metal line were employed. The billetextension unit was not described in detail but evidentlyconsisted of a mechanical clamp on a frame thatmoved along the strand by means of adjustment screwsdriven by an asynchronous electric motor. The lengthof the billet produced was 3 m; the casting rate was0.70.8 m/min. The surface quality of the electrodesobtained by horizontal casting was much better thanfor other casting methods. The depth of the junctionsbetween increments was 13 mm; they had no oxidefilms and were not regarded as defects.

At Uralmash Production Center, continuous castingof highquality round billet was investigated in the 1980s[14]. In the horizontal machine developed, extension ofthe billet was accompanied by its rotation from themotionless mold. Billet (diameter 140150 mm) wascast at a mean rate of up to 3 m/min. The extensionincrement was 30 and 50 mm; the ingots rotation speedwas 100 and 60 rpm. Casting with rotation eliminateddisplacement of the thermal center, reduced chemicalinhomogeneity over the cross section and geometricdistortion, reduced the thermal stress in the ingot crust,and hence reduced the likelihood of longitudinalcracks.

Successful operation of the experimental horizontal machines at the AllUnion ScientificResearchInstitute of Metallurgical Machinery and the Ukrainian ScientificResearch Institute of Metals, as well as

the machine at Tulachermet Scientific ProductionCenter, prompted the adoption of a construction program for horizontal machines in openhearth shopswithin the Soviet Union, so as to replace chill castingwith continuous casting [15]. The first such system wasa fourstrand machine based on the design developedby the AllUnion ScientificResearch Institute ofMetallurgical Machinery and went into operation in1986 in bar production at Karagandinsk MetallurgicalWorks (Fig. 8) [16, 17]. On that machine, billet wasproduced from carbon and lowalloy structural steel,for subsequent rolling to periodic profile, so as toobtain rebar for ferroconcrete structures.

The design of the machine employed modularthickwalled molds with drilled cooling channels. Inpractice, molds of new design with a thinwalled sleevewere introduced. These molds, developed by the AllUnion ScientificResearch Institute of MetallurgicalMachinery, were characterized by a square workingcavity and cylindrical hole for insertion of the metalline. This permitted reduction in copperalloy consumption by a factor of 45, thanks to the lower flowrate and longer life of the sleeve. As a result of theincreased heat supply from the ingot to the sleeve, thenumber of gaps in the liquid steel beyond the mold wasreduced. The characteristics of the horizontal continuouscasting machine at Karagandinsk MetallurgicalWorks are as follows:

The metal intakes and molds were connected bygraphitefireclay metal lines, whose working life corresponded to 20 t per strand [18, 19]. Separating ringsmade of hotpressed ceramic (based on boron nitride)were tested in some castings. The life of the ringsextended to three or four successive castings; the massof the cast metal was 62 t per strand [19]. Between1986 and 1995, around 200000 t of steel were cast. Theactual capacity of the steelcasting ladle was almosttwice the design value. The machine was shut downwhen bar production at Karagandinsk MetallurgicalWorks was eliminated.

Billet cross section, mm 145 145160 160

Number of strands 4

Ladle capacity (design value), t 64

Number of metal intakes 2

Metalintake capacity, t 4

Inclination of technological axis, deg

5

Billetextension mechanism Hydraulic

Mean casting speed, m/min Up to 2.2 m/min

Type of cutter Hydraulic pendulum cutters

Rated power, kV A 1000

Length; width; height, m 35.0; 11.2; 4.8


Fig. 8. Horizontal machine at Karagandinsk MetallurgicalWorks [16].



After the successful introduction of a horizontalmachine at Karagandinsk Metallurgical Works, a twostrand machine developed jointly by Ukrainian ScientificResearch Institute and the AllUnion ScientificResearch Institute of Metallurgical Machinery wasintroduced at Sulinsk Metallurgical Plant. Thismachine was used to cast carbon and lowalloy steelfrom a 30t ladle as 160 160 and 175 175 mm billet.The machine operated from 1990 to 1993. The operation of the horizontal machines at Karagandinsk Metallurgical Works and Sulinsk Metallurgical Plant demonstrated the possibility and expediency of using suchmachines in the reconstruction of metallurgicalplants.

The actual source of Soviet designs for horizontalcontinuouscasting machines is the machine developed at AllUnion ScientificResearch Institute ofMetallurgical Machinery in the 1970s under the guidance of Molochnikov and Patrikeev. All the horizontalmachines considered earlier may be characterized asunits with unidirectional billet extension, in which theliquid steel is supplied to the mold at one end, and thebillet extends from the opposite end. In view of theperiodic character of casting and the need for an endwall at the point of metal supply (a collar in the moldor refractory nozzle), the process in such machines isnot continuous, in fact; rather, it corresponds to periodic growth of the ingot crust.

In the new type of machine developed at the AllUnion ScientificResearch Institute of MetallurgicalMachinery, the liquid metal is supplied to the mold atthe center of the working cavity through a hole in theroof (Fig. 9). In this case, during the simultaneouscontinuous extension of two ingots with reciprocatingmotion of the mold, there is always some distance Lbetween the casings that form, when the crust thickness is practically zero. Hence, in this bidirectionalmethod, billet with a smooth surface may be obtained;the junctions between increments that are seen in unidirectional casting are not formed in this case.

To investigate this process, two experimentalmachines were manufactured and installed. Billet ofnozzle round, square, and rectangular cross section

(characteristic crosssectional dimension up to175 mm) was cast on one of the machines (Fig. 10).The metal was smelted in a 1.5t arc furnace. The second machine casts 350 400 mm blooms and 150 500 mm slabs. The steel is cast in a 5t arc furnace. Arange of materialsfrom carbon steel of regular quality to highalloy corrosion and heatresistant steel, aswell as nickel alloys (including pure nickel)was caston these machines [20]. In developing the design ofthe machine components and in trial casting runs,methods of restraining ingot rupture in the middle ofthe moldat the point of metal supplywere investigated. In that case, there were practically no traces ofmold rocking at the ingot surface over the wholeperimeter. Together with the elimination of secondarycooling of the steel between the metal intake and themold, this permits the production of highalloy steelbillet that may be rolled without surface trimming on abidirectional horizontal machine. To confirm thisfinding, an experimental batch of X18H10T steel wascast to 140 140 mm billet at the AllUnion ScientificResearch Institute of Metallurgical Machinery,with the assistance of specialists from the Central ScientificResearch Institute of Ferrous Metals. At Serp iMolot Metallurgical Plant, the billet was then rolled tostrip without the surface trimming usually employedfor this steel [21].

The production of thin 4050 500 mm slabs and150 150 mm bimetallic billet (layerthickness ratio inthe range from 1 : 1 to 1 : 4) was also attempted on theexperimental machines.

On the basis of the experimental machines at theAllUnion ScientificResearch Institute of Metallurgical Machinery, a fourstrand horizontal continuouscasting machine was designed and manufactured forKramatorsk Metallurgical Plant. The machine wasused to cast 175 175 mm billet from a 65t ladle.After hot tests with the participation of specialists fromthe Central ScientificResearch Institute of FerrousMetals, economic problems prevented the industrialoperation of the machine. The AllUnion ScientificResearch Institute of Metallurgical Machinery supplied an analogous twostrand machine for the casting

1

23

45

L

Fig. 9. Horizontal continuouscasting machine with bidirectional ingot extension: (1) metal intake; (2) metal line;(3) mold; (4) ingot; (5) extension cell.

Fig. 10. Twostrand horizontal continuous barcastingmachine at the AllUnion ScientificResearch Institute ofMetallurgical Machinery.

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of 145 145 mm billet to Japan, for one of theKawasaki Steel plants (Fig. 11). The machine was usedto cast carbon and alloy steel from 30t ladles.

It is obvious that considerable experience in thedevelopment and operation of horizontal continuouscasting machines was acquired in the Soviet Union. Atpresent, however, no horizontal continuouscastingmachine is in operation within the Commonwealth ofIndependent States, although its benefits are obvious,especially for mini mills.

In our view, it is wrong to regard radial and horizontal machines as opposites. They cannot and shouldnot be competitors; rather, they represent two differentapproaches. Horizontal machines are inappropriate atplants with highspeed oxygen converters or powerfularc furnaces of moderate or large capacity and withladletreatment systems, where casting in large seriesis possible and infinite rolling and casting technologyis applicable. On the other hand, we are presentlyinterested in mini and even micro mills with smeltersof capacity 612 t, where highproductivity radialmachines are inconceivable [22]. In that case, horizontal continuouscasting machines may prove useful.

We now consider some engineering aspects of horizontal continuouscasting machines.

It is especially important to reduce capital costswhen planning output of 100000120000 t/yr or less.In that case, the plant should make the maximum possible use of existing production buildings and infrastructure. The construction of new buildings for suchsmall plants is economically unviable. In that case, itmakes sense to use a horizontal continuouscastingmachine, whose height fits within shops equipped withgantry cranes of height 78 m. Given the smaller massof the horizontal machine in comparison with anequivalent radial machine, we may expect (25)foldreduction in capital expenditures, depending on theproductivity.

The small size of the horizontal continuouscastingmachine may prove valuable not only in setting up a

new plant but in reconstructing existing systemsforexample, where it is necessary to organize the production of a broader billet range. In that case, it is possibleto install equipment in existing free space, and considerations of size and mass may be decisive in selectingthe best option.

When reconstruction at the Chapparal Steel plant(Baltimore, United States) boosted the output of thesteelsmelting department, there was a need to supplement the existing radial bloomcasting machine withanother continuouscasting machine [11]. A twostrand horizontal machine was installed for reasons ofspace and steel quality.

Another example is the installation of a horizontalmachine in the early 1980s at Serp i Molot Metallurgical Plant, for the production of consumable electrodesused in electroslagremelting furnaces. To reduce production costs here, rolled electrodes were replaced bycontinuouscast electrodes. A small horizontalmachine was introduced within the electroslagremelting department. Some of the metal previouslysent to the radial machine was cast on the horizontalmachine.

Note that the size and mass of horizontal machinespermit their use in processing ferrousmetal scrap ininaccessible regions of Siberia and the Far Northinother words, in locations where capital outlays form avery large proportion of total operating costs [22].

The sealed joint between the metal intake and moldin horizontal machines permits the casting of highalloy steel and alloys with little liquidmetal heatingand low casting rates. A wide range of steel may be cast(with sufficient billetextension frequency), thanks tothe lack of secondary oxidation of the metal. On SMSDemag, Krupp (Germany), and Davy Loewy(France) horizontal machines, a wide range of steelsmay be cast, besides carbon and alloy steel, accordingto [23]: austenitic chromonickel and chomumnickelmolybdenum steel (including steel with highS, Ti, and Cu contents); ferritic chromomolybdenumsteel (including steel with high S and Ti content); corrosionresistant chrome steel (containing 0.31.1% C);ledeburitic chrome steel (up to 1.52.1% C); andhighspeed steel.

Casting at low rates yields highly satisfactory billetmacrostructure. At the BGH Edelstahl Siegen plant(Germany), a casting speed of 1.61.9 m/min ismaintained on a sixstrand SMS Demag machine forbillet with a diameter of 12090 mm, in order to suppress axial liquation [24].

On account of the direct connection of the metalintake and the mold in horizontal continuouscastingmachines, billet of small cross section may beobtained. This permits the use of the machine in theproduction of rolled steel at extremely small volumes:up to 30000 t/yr for carbon and alloy steel and even500010000 t/yr for highalloy steel and alloys. Theeconomic benefit is largely due to the reduced mass

Fig. 11. Horizontal continuouscasting machine with bidirectional billet extension for a Kawasaki Steel plant.



and size not so much of the continuouscastingmachine as of the rolling equipment.

Casting to round billet is difficult on any continuouscasting machine, owing to the likelihood of ovaldistortion with nonuniform cooling on shrinkage andconsequently to the appearance of longitudinal cracks.On horizontal machines, in view of the high ferrostaticpressure in the zone of initial ingot formation, solidification is relatively uniform, which facilitates thecasting of round billet. Note that 28 continuouscasting machines producing small round billet (cross section less than 150 mm) were in operation around theworld in 1990. Of these, 19 (68%) were horizontalcontinuouscasting machines [25].

Horizontal machines with bidirectional billetextension are of interest for the production of smallproducts whose manufacture generally involves technological difficulties (for example, in working withcorrosionresistant steel that contains titanium or withelectricalengineering steel that has an elevated siliconcontent). Bidirectional horizontal continuous slabcasting machines may be used in casting 40150 250700 mm highalloy steel and alloy billet from25t ladlesin other words, where radial continuouscasting machines for slabs and thin slabs are uneconomical [20].

The good prospects for horizontal machines areconfirmed by numerous queries from potential customers, within and outside Russia. As yet, however, noindustrially operating machine exists as a demonstration model for customers.

In the 1980s, horizontal continuouscasting wasmainly regarded in the Soviet Union as another optionfor the reconstruction of metallurgical enterprises(Karagandinsk Metallurgical Works, Sulinsk Metallurgical Plant, Kramatorsk Metallurgical Plant).(Elsewhere, by contrast, horizontal machines wereregarded as a means of casting highquality steel.)Moreover, manufacturers were interested in horizontal continuouscasting machines. Thus, specialists atAllUnion ScientificResearch Institute of Metallurgical Machinery considered the possibility of installingsuch machines at Usolmash Production Enterprise(Irkutsk region) and at a manufacturing plant in Orotukan (Magadansk region). However, economic difficulties not only terminated those projects but eveneliminated existing machines.

In the 1990s, horizontal machine were regarded ascompetitors of traditional continuouscastingmachines. The development of horizontal continuouscasting was hindered mainly by the 50% lower productivity relative to radial casting, the shorter mold life, andthe demand for ceramic nitride in the metal lines.

Certainly, the life of the mold sleeves in horizontalcontinuouscasting machines is less than in radialmachines. However, the consumption of copper components in the machine at Karagandinsk MetallurgicalWorks is 0.12 kg/t, which corresponds to an expendi

ture of no more than 100 rub/t (at mid2008 prices).Ideally, this figure would be lower. But what alternativeis there for a mini mill of output 100000 t/yr? In casting single melts from lowcapacity furnaces, a capitalintensive radial continuouscasting machine would beidle for half the year.

The need for a separating ring in horizontal continuouscasting machines is on a par with the need for asubmersible tube and dosing nozzle in radialmachines. Depending on the grade of steel and thecasting time, the nozzle material may be selected:from graphite fireclay to pure boron nitride. The life ofnitride rings permits their use in casting individualmelts several times in a row [19]. Their contribution tothe final production cost is even less than for themolds. Contrary to the prevailing view among designers of horizontal machines, the issue of the separatingring leaves scope for discussion.

Note that the foregoing applies to the casting ofcarbon and lowalloy steel. In the case of alloy andhighalloy steel, the productivity of the machine, themold life, and the need for a separating ring are of noconcern. Lately, however, metallurgists have grownfirmer in their opposition to horizontal continuouscasting machines. We may hope that these misunderstandings can be resolved in discussions with specialists. At present, doubts regarding the applicability ofhorizontal continuouscasting machines on thegrounds that none are currently operational in thiscountry may be traced mainly to entrepreneurs, whoare uncomfortable with the risk involved in selectingthis technology. However, the experience gained bySoviet specialists in developing and implementinghorizontal continuous casting is enormous, and horizontal machines are operational in countries aroundthe world.

Conditions today are more favorable for the use ofsuch materials. We need new principles for the creation of micro mills characterized by low capital outlays, short technological cycles, flexibility, and lowoutput.

Various problems must be solved in the organization of micro mills. Thus, smelting and casting linesmust be created on the basis of smallcapacity furnaces, for which largescale casting is inappropriate.The cross section of the continuouscast billet must bereduced as much as possible, so as to permit the use ofsmaller and lighter rolling equipment. The micro millmust incorporate existing structuresas a rule, manufacturing buildings, characterized by small height (bymetallurgical standards). Horizontal continuouscasting machine may play a considerable role in the solution of these problems.

REFERENCES

1. Schwartzmeyer, W., Continuous Casting: Developmentand Application (Russian translation), Moscow: Metallurgizdat, 1962.

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2. Chukhrov, M.V. and Vyatkin, I.P., Nepreryvnoe gorizontalnoe lite slitkov metallov i splavov (Horizontal Continuous Casting of Metal and Alloy Ingots), Moscow:Metallurgiya, 1968.

3. Perevalov, N.N. and Filimonov, V.A., Trends in Continuous Casting with Similar Cross Sections of the CastBillet and the Final Product. II. Production of Cast Billet of NearFinal Cross Section on Horizontal CastingMachines, Chern. Metall.: Byull. NTI, 1996, no. 4,pp. 1928.

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Horizontal continuous casting of steel