DE1433028A1 - Method and device for monitoring and controlling the foaming and calming of steel during continuous casting - Google Patents

Description

Center National de Recherches M4tallurglquea,

"Process and device from ülserwaoheja and taxes ä® & foaming uud the calming of steel in the continuous GuS

Me present invention relates primarily to a method of monitoring and controlling foaming and the calming of steel during continuous casting

In de ^m process for the continuous casting of steel it 1st begannt that the blocks obtained from an unkilled steel Iasen I in its mass in the depth distributed cavities or of very different kinds have · However, a surface layer, the thickness depending on the type of the metal and depending on the casting conditions changes, free of bubbles, and the surface quality of the Walser products depends precisely on the presence of this layer, usually known as "bacon"

The dioke of the bacon is directly related to

the degree of foaming of the metal, ie the intensity of the

809802/0302

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day _; Solidification of the steel accompanying gas development. This gas development results mainly from the formation of. . Carbon monoxide and carbon dioxide during the cooling of the steels by the .Reaktion of carbon and oxygen "at the time the casting @@ d in d @ m-mentioned steel were dissolved" - By, one controls the end of this reaction, - man: , seeing the »foaming of Stahl® hehezr and consequently influencing the« thick © & ®b bacon · ". '* ·

I £ g * .1 'd @ ff drawing, just as an example - but nieht is to be interpreted in a limiting sense _9. provide an understanding of the invention »It shows the appearance and distribution of the bubbles in a cross section of blocks with different degrees of foaming.

The? -. & © rsehßitt a 1st- #. © r of a JBloQkß from a completely calmed steel "while b, c " . d "e _f f and g are the cross-sections - of iESiei · starter.-foaming blocks are · How isER sees? For Er-EieliMig plx & em Speeke -w & n of sufficient thickness, more intensive blistering must be brought about than when casting blocks of type d. After all, excessive foaming is sa. avoid, because it complicates the OSPs and calls strengthens Metallauswürfe M © Rvor, AEIS the origin of serious O'bsrflädh®nfehl @ r @ ä v Block® are and DI® flbe ^ elles Major

to have

Wünaeht mmm schäumead® Block® aus @? S @ ugen ₉ , the extraction of structures of the types e> f is to be strived for. The structure g is also acceptable, but brings with it the danger of steel owls being thrown out of the blockfora.

809802/0302 -3-

It is advisable to regulate the foaming of the steel between very narrow limits so that a structure of the type e, f or g bit is obtained with a thickness of bacon which, according to practical advice, must be at least 15 ■■.

As has already been said, the degree of the Foaming of steel essentially depends on the relationship of the surselt of pouring carbon into the block fora la metal and oxygen »b. For this reason, nan -was lix.upi; mainly concerns the soft and super-soft steels that are at the end of the fresh * have an excessive oxygen content in comparison to sub carbon content - at the time of casting, e.g. in the pan, a certain amount of a deoxidizing agent » such as carbon or manganese. For reasons of economy, the amount of these additions is limited to the minimum, so that the metal in the ladle generally has a high oxygen content in relation to its carbon content and the formation of carbon monoxide and carbon dioxide by reaction of the carbon dissolved in the steel and oxygen is initiated as soon as the cooling begins. If the reaction occurs too strongly in the pan itself, it will through Adding a small amount of aluminum to the steel moderately binds part of the oxygen without developing gas The steel to be cast retains a sufficient amount of oxygen to ensure good foaming in the block form.

809802/0302

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BAD OBlQSNAL

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Bas 4eia Sevens-taad "tier ETt iadisag feIM @ sd © · ¥ © rfate @ a ist .. la des · Haiipt® @ © fe © Iadmrsfe gekeaEseiöfenet ^ ta§ a» © ine® Bleek des £ ort2airf © &<i @ s Suase's elm © Si © lite® © asiaag this Blchteaeaieimg.eeneiis Aase ± e & ea .'- ffte:? BIocSt «alsi®leitet m-Λ la 'Aibliiiigigkeit ^ on the admission τοη Deexydatlonsadttelii» aa steel is regulated in iha the corresponding to the degree of calming desired

Gain structure. .

8 0 9802/0302

This density measurement is advantageously carried out by penetrating electromagnetic rays of a certain wavelength, preferably gamma rays sent through the block and the intensity values of these rays before and after the Passage through the block can be measured «We know that the absorption of radiation through a certain thickness of the Body depending on the presence and extent of structural irregularities, and in the case of metals from The presence of bubbles in the path of the rays changes "

Preferably, low energy gamma rays are used, whose radiation source has a sufficiently long service life, such as cobalt 60 or cesium 137

R-in an important application of the method according to the invention consists in that the bundle of the passing through the block Radiation is aligned so that its axis is at least one Place that limited by the minimum layer of bacon you want Zone of the block hits "

It has been found advantageous to link the determination of the last addition of sedatives to the steel with the ratio of the intensity values of the radiation passing through the block after and before passage through the block are «The addition of sedatives can be in solid form (ζ. B. in wire form) or in liquid form«

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BATH ORIGINAL

8098 02/0302

: 1433G28

The present invention also has one device stubborn Exercise of the procedure described above for counter

.Measuring device is Ib-.we seat borrowed · characterized » that they are a source of penetrating radiation » preferably for gamma rays ». as well as a recipient for this radiation and a device for adding tranquilizers au »steel contains»

The continuously working gate direction for the addition of the sedatives to the steel from the radiation receiver made dependent.

The following are not limiting but are examples only

the drawing ^ figures to be understood, the understanding of the Principle »facilitate density measurement according to the invention. In all of these figures the same reference numerals are used represent the same elements.

FIGS. 2 and 3 show, in a simplified ^{manner, the case of a radiation, which} a block 29 in a parallel to a side 36 of the cross-section of that blook 29, namely in the case of a compact area and in the case of a non-compact area because of internal bubbles 33 present Area of metal *.

The _{intensity of the incident radiation 30 is designated by l o} , the intensity of the radiation 31 exiting in the case of FIG. 2 with I, and the intensity of the radiation 34 exiting in the case of FIG. 2 by X *.

BATH ORIGINAL

809802/0302,. '~ ^η ~

The amount of the ratio I ^ characterizes the

Density of the irradiated area 35 · This amount becomes detected by a receiver 39 of some known type, for example a scintillation counter, a Geiger counter or an ionization chamber. The one from the radiation receiver detected energy is amplified and by means of a device known per se and not shown Transferred to appropriate Beiais, either a scoreboard or actuate the signal generator if the kinstelluag of the feed regulator for the clesoxidizing agent done by hand » or on a suitable mechanism that automatically influences the supply government, if one has an automatic dependence or cessation of that supply wants to bring about · in particular lall the use of a deoxidizer in wire form (e.g. aluminum wire) the relays can have a speed controller control, which sets the speed of the unwinding of the wire spool and, as a result, the amount of in the liquid steel 8 introduced deoxidizer regulates

You see Figures 4 and 5 see mat Ib oh the case of one Cast ingots 29 of rectangular cross-section. The radiation 30 is then directed parallel to the shorter hexagonal ridge 37 »

In this case, as in the case of blocks with square « intersects the axis of the incident radiation 30 in "Ine" Distance 38 from the surface 37 of the block 29 is set, at least the minimum thickness prescribed for the bacon equal to 1st «

80 98 0 2/03 02

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If you want to prevent the consumption of an excessive amount of deexydatioasElttels * β © Sunday «maa _p as shown schematically in Fig. 6>'cugleloti two parallel radiations 30 and 40 use» sera axes different® distance © toe of the frontal surface «37 half »namely the one a distance 38 equal to the minimum _{thickness of the Speek s} the ariter® of a distance 4IgIsIaSx that of the Sgeekdiet not zm. The limit value "Under & i @ s && Bedlngrages. the Styahlungeasseiger 39 comes into action" vm. to increase the credibility of the Desoxvdatlonssittsls " _: as soon as the ratio I _n der lateaeitäts ^ srt © Sex ¹ » and a ns trot ends ö, radiations - eia @ a srfabs'iängsaäiig vü> n known @ n kfitiscsh © ^ M®tw & g üfeersekreit © t »$ ääire & $ 4 © r aweit®

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In this "Aneeiger 42 ant er 39-neß .teritisofcea - amount" sinks _for what "in-Ansei © h © -ffi See ¥ l511igem ferQ © hwimt1, © a" Äer "" bubbles 33 ie fiefen- -abBt " and 41. voa the "Oberfliehe 37 would be"; - ^v -: -.--

der StsraMl ^ ii 3®. Hfe @ K © t®igt _f: becomes Si®; eehematieeh la. flg-ur T "

Bia Stomhlisiag JO becomes nics & t

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wise inclined at 45 ° »Mtei a 2®il | e.ne @ Queraobnlttain «Ines Etetsnd 44 voa - .. the edge 45 durohetr & lt: -will ^ Distance with de? M part? O2? H @ rg @ li @ nd @ E examples considered en Route 38 In the following relation atelit

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FIG. 8 schematically shows the case of a block 29 circular cross section again

You Figures 9, 10 and U represent schematically a measuring device for the impermeability of the block after the Present Invention FIG. 9 is an elevation view of FIG Zentrlerrolle, Figure 10 is a partial plan in the Rohe of Centering rollers of the device placed on the continuous block 29 and FIG. 11 a partial section of this device in height

the measuring radiation between the radiation source 46 and the Radiation indicator 39 "

In these figures, 47 and 48 designate the rollers for centering the measuring device on the block 29x46 is the radiation source, 39 the receiver of the beam emerging from the block 2 $ , 49 the carrier of the rollers 47 and 48. This carrier is on the Arm 50 is suspended and is pressed against the block 29 by the springs 51 in such a way that the rollers 47 and are kept in contact with the block 29 46 and 39 wears 55 1st a radiation protection screen

Figures 9 to 11 do not show the apparatus for measurement the intensity ratio of the incoming and outgoing radiation, and also, neither the amplifiers nor the measuring effects on the display devices or on those controlled by them Servo motors transmitting relays, since these facilities of known commercial type are * Yes »is by the way self-mutually

"80 980 2/030 2 BADORiGlNAL

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Of course, the measuring device can be carried out in various ways, without leaving the principle of the invention itself. -.

One thing to note is that the radiation source and receiver existing device 46-39 below the Blockfora in one Height should be arranged where the children of block 29 a Thickness has reached which is the desired minimum thickness of the bacon exceeds.

The minimum distance to be adhered to in order to achieve that thickness between the exit level of the block form and the level of the Radiation device 46-39 is by empirical study d greater than or equal to L ~ Y given, also for horizontal continuous cast applies? where d means the specified distance in meters,

% the amount of the desired thickness of the bacon, expressed in centimeters, ie the bubble-free circumferential layer of the block, V the speed of exit from the fora in meters per minute ·

Is for example the thickness of the bacon to be achieved L 2.2 ok and the exit velocity V * 0.6 a / aln, so is the! find st distance of their radiation device tob Exit the gate "

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If necessary, when adding the deoxidizing agent

so the correction to be applied is known as a delay of

SAD OBIGlNAL

803802/030 2

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In the following exercise and examples the special case of the use of aluminum as a deoxidizing agent is assumed for the sake of simplification »although the considerations made also apply to the case remain valid in which other deoxidizers ale aluminum to be used.

The addition of aluminum in the Blockfora takes place in general in the solid state "Sas aluminum is then either la JPorm smaller pieces (granules, lozenges and the like), or added in the form of a continuous wire * in de ^a immediate area is brought the Stahlgaßstrahls" 17a di »

a

To facilitate handling »If the aluminum supply is on egg coil moved by an automatic mechanism » which run the wire at a manually adjustable speed »b ~ Gives. In the case of using aluminum in a liquid form for deoxidation the stock of the latter is in elnea Of # a contain «the one above the peeling point of the aluminum lying! temperature is let · Des melted aluminum is led from the furnace to the block mold through its suitable pipe », as iigur 12 shows · In this figure 12 the container 2 flows contained steel 1 through the nozzle 3 in a continuous · »jet 4 into the block form 5 * w © he forms the continuous block 6 *

of the liquid part 7 continuously through the liquid aluminum 8 from an oven heated by means of electric heaters 10 § "This is calmed down on one above its melting point Aluminum 8 kept at a constant temperature flows continuously through the nozzle 11 and the line 12 in a jet 13 the load

809802/0302 ■ »« «« «■ _ ₁₂ _

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in the ■ © f © a. f -sslMi, @ S! t @ 2ii i ^ m @ lsl®ltiffig 17 regulated something

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«Ims® Unt @? Te £ @ k9 mng®MQgm $ der in one at 20 ' L & li-mtig 21. on dl» -.- Leltvag 1® a ^ sgeil ^ t «&& dmrekein i @ f ®l®ygaa 22 is controlled ·: Di © Äa ^ HiBgeBSliwiaätgleit dee .8 let tor @ h Se »M? eä & ant® £ s® & i © d 23 swiss ^ s" des ies Al ^ iimiia ^ ales 8 * tuid; i * r «tira Müsäsag 24 der -taitlaat * M® «s © Mündusg 24 i © fäit © 1®« ® (in de?

ni © fet en) H®g®lst®pfes' ¥ © rs © k @ Ss Help with souls ©

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regulates the 8 aluminum feed and closes it completely with the suction

An especial "important variation of the device shown in üg · 15 · In this fi _fc for iet © in at 13 * S sealed furnace equipped with a lifter 19, which the

directs molten aluminum 8 into the block mold 5 the supply of aluminum 8 is regulated by changing the gas pressure inside the furnace 9

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80 98 0 2/0 30 2

Claims (9)

Claims 1.) Procedure for monitoring and controlling the Foaming and calming of steel with continuous Casting, characterized in that a density measurement is carried out on a steel block that is being cast continuously made, from this exact indications about the structure of the block can be derived, and as a function of these indications the addition of deoxidizing agents in
to the steel is regulated to / this the desired Maintain a structure that corresponds to the degree of calming. 2.) Method according to claim 1, characterized in that that the density measurement is carried out by a penetrating electromagnetic radiation through the block "of a certain wavelength looked through and..." a comparison is made of the intensity values of this radiation before and after the passage through the block 3.) Method according to claim 2 ₉ characterized in that the radiation consists of gamma rays. 4.) The method according to claim 3, characterized in that the gamma-ray weak energy and have a long radiation level. lifespan is used. 5 ·) Method according to one of claims 2 ■ - 4, characterized in that as a radiation source Cobalt 60 or Cesium 137 is used. 6.) The method according to any one of claims 2-5, characterized in that the bundle of the penetrating Radiation is passed through the block in such a way that its axis is at least one of its Make the inner area of the block, delimited by the minimum layer of bacon you want. 7 «) Method according to claim 6, characterized in that that the sizing of the addition of sedatives to the steel on the amount of the ratio the radiation penetrating the block after passage and is made dependent either manually or automatically before passing through the block. 8.) Method according to claim 7, characterized in that the final addition of sedatives takes place in solid form, for example in wire form, or as a liquid. 9.) Apparatus for exercising the process according to one of claims 1 - 8, characterized by a radiation source, preferably for gamma rays, a receiver for this radiation and a device for adding sedatives to the steel. 10 ·) Device according to claim 9, characterized in that the continuously operating device for the addition of calming agents to the steel is made dependent on the information provided by the radiation recipient / The patent attorneys Weir, Seiler, Stehmano 809802/0302