DE1433464A1 - Process for the production of cast steel or cast iron - Google Patents

Description

364 / CE 2389A / LPC A 68653

Dr. Expi.

Applicant: Combustion Engineering, Inc _e Windsor, Connecticut, uSAe

Process for the production of cast steel BEZW. Cast iron

This invention relates to cast iron type and iron alloys particularly relates to a new and advantageous method for the production of iron alloys

Generally speaking, the cornerstone of the invention is a new iron alloy to deliver which has the advantages of ordinary cast iron and which combines other practical advantages »

Other general considerations are to provide a new method of making an iron alloy capable of producing a To withstand volume expansion when exposed to repeated periods of heat and cold over a wide temperature range and which can also be poured into molds without one must take into account the shrinkage of the dimensions of the casting.

A special point of view is that this iron alloy with With the help of metal smelting and casting equipment such as those available in a conventional foundry that usually makes gray cast iron o

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Another task is to carry out the production of the Iron alloy using conventional metal melting and ussing equipment with the further use of certain additional devices that can be adapted to the usual equipment.

A part of the gate of the invention consists in the elimination of rejects. The cost is no greater than the ordinary "cast iron" > The foundry staff does not need to be specially trained either to become"

According to the invention, this is achieved in that the melt After the withdrawal, silicon-containing additives are added first, so that the melt then undergoes an inoculation process with calcium carbide and, more rarely Earth for the purpose is subjected to the sulfur content to reduce, to refine the grain size of the coal and at least Part of the coal from the liquid into "the granular form." to transfer and that finally the melt obtained in this way is poured into a mold.

An embodiment of the invention is shown in the accompanying drawings. 'Drawings shown. . ■. ■ .

Fig. 1 is a sectional view of a cupola furnace showing the particular Contains filling and whose pouring channel is equipped with devices; around the filling when they put the oven in melted Leaves form to supply a first biliziümlegierungselement measured ^

i'ig. 2 is a sectional view of a ladle, which is disposed under the Kupolofenausflußriniie containing the molten metal ·, the first added the üiliziumlegierungselement · 'to increase, after previously another "silicon alloying element has been placed in the ladle lsi ^r

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Figure 3 is a top plan view of the ladle as seen from line 3-3 the Pig. 2;

Fig. 4 "tilts the ladle", the figures 2 and 3 "after it has picked up the molten metal filling and from the cupola of Fig. 1 to another location (Fig. 4) was brought; there a vaccination device (also there Teranachau light) is lowered into the molten metal in order to inoculating it with calcium carbide and other additives;

Fig. 5 shows the ladle of the previous figures after it was taken to a third or a place for pouring the metal, where the contents are poured into hand pans was transferred to pour it into molds for making clay castings.

Fig. 6 is a cross-sectional view of one of the aforementioned molds as they are removing molten metal from the aforementioned hand pouring pans takes in;

7 is a view of a typical casting as shown in FIG after solidification of the cast metal from the casting form of Fig. 6 has been taken.

Exemplary embodiment for the composition of the metal

The present invention provides a ferrous product that includes approximately $ 90 iron and others listed below Components contains:

Total carbon content 3 »25 % minimum

Bound carbon 0.5u $ 6 maximum

Silicon 3.80 # - 4.20 %

Sulfur 0.01 % maximum

LIagnesitUB 0.14 # maximum

ο η r \ ο " '■>' η r * n η

Phosphorus $ 0.25 maximum

Manganese $ 0.50 minimum

The alloy according to the invention generally has the appearance from solidified cast iron, but is easy to work with.

It is somewhat harder than ordinary cast iron and has brinell * see hardness numbers of 220 - 25U and has a "considerable" greater tensile strength in the order of more than 422 kg / cm (6,000,000 lbs per sq..in »j when dropped or is struck, it emits a bell-like sound, similar to ötahl, · This shows a general i'ehlen of carbon in the form of a cam and that at least a part of the carbon is in granular form. That is lietall somewhat more brittle compared to steel and in this respect is comparable to ordinary cast iron.

The metal has a solidification time very similar to that of Ootahl, but it is found that all castings are the same. Have dimensions like the molds in which they were cast. To put it another way, the models that are needed to build the molds for this metal do not need to take into account the shrinkage of the finished casting. This characteristic of the light shrinkage has been tested for castings of small dimensions up to 304 mm (1 foot) proven., but also applies to castings of larger dimensions _o

For practical use it is synonymous with the fact that this new cast iron alloy combines the advantages of ordinary cast iron with further resistance to bulking when exposed to repeated periods of heat and cold over a wide temperature range. Δ, ~ Ά _Ο is found on the basis of experiments that a casting made of this metal, which has the shape of a grate holder like ", Figo 7, up to 25 repeated periods of heat and cold from room temperature to 870 ⁰ C (160O ⁰ P) can withstand, with an associated change in volume, which is limited to a maximum of 6.50% o

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For applications "exchanging for furnaces and anueren heat systems such as boilers and similar is" b this üharakteristikum small increase in volume "at elevated operating temperatures extremely valuable and makes the new metal from the economic point of view very advantageous sudden be holders for fire grates ι * of this metal under the same Cast iron conditions several times more and are equally better than the low chromium materials previously used for grates.

The new semolina technique for the production of the new metal.

Figures 1-7 cLsr drawing illustrate foundry equipment with which the metal described above successfully and in an economical and reliable way and with extremely low reject losses. can be produced _o

Such devices consist of: a common cupola furnace C, which is supplemented at its outflow channel 10 by a measuring device 24 in the manner of FIG. 1; a ladle K, also of the usual The type shown in Figures 2-5 having a capacity of 3175 kg (7,000 pounds); a special vaccination device (shown schematically in I Fig. 4)> that on a-second Point of the production aisle can be lowered into the ladle K; Hand pouring pans of the usual design, which at H in the Figures 4 and 5 are shown, and with which molten metal they are at a third point in the production run from the Main pouring ladle K have received in molds M for the production of the castings (^ is poured »

As shown in FIG. 1, the manufacturing process is started with the loading of cupola C with successive layers usual additions. The cupola itself has the usual drainage

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gutter 10, and the heat will melt the metal filling through the usual coke combustion 11 with the help of combustion air, blown in by a fan 12 through tube openings 13 is generated, the heat released in this way "brings the metal over the lower bed of coke to melt, and drops, this one Metal flows down between the coke pieces 11 and out of the cupola via the discharge channel 10.

The additions for a 2900 kg (64u0 pound) heavy metal filling, which the ladle K is to receive after melting is placed over the coke layer 14, which here consists of 181.2 kg (400 pounds) Coke is made. A layer 15 is placed over it, which weighs 453 »6 kg (1000 pounds) of mold steel is made of various shapes commonly available in foundries, but mostly free of rust or Is oxidation. A further layer 16 is laid on top of this 90.8 kg (200 pounds) of coke, whose primary purpose it is, is the carbon content the special filling to enlarge. Over 16 is one 680 kg (1500 pounds) layer 17 laid by a lump, which have a relatively low sulfur and phosphorus content has (typical of the Pittsburgh area. There is one on I7 200 pound (90.8 kg) layer of coke 18, similar to 16 previously described, and over 18 is another 226.5 kg (500 pounds) sheet I9 of structural steel. Above a number of equal layers are arranged in these filling layers, which are denoted by 14 * to 19 *, lim metal of the desired To obtain composition, instead of layers 19 and 19 'of structural steel, equal amounts of scrap material of the present Process to be used »

These filling layers 14 - 19 'are of the cupola C, which is in the usual Way works, fused other cupola fills below and above 14 - 19 'add some metal to that special one Add charge so that approximately 29U0 kg (64OO pounds) of molten Filling can flow into the main pouring pan K via the spout 10.

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Before the melt is drawn off, at 2u - 5U kg (110 pounds) are placed on the bottom of the semolina pan K. This is a granulate and can be transferred to the location of the main pouring ladle K indicated in FIG. 2 in suitable containers, such as buckets of the pig . 2, to be worn. The range of grain sizes for this material can vary between 19 mm (3/4 in.) And 342 mm (12 in.) Screen fineness. The chemical additions of the silicon iron used here consist of: silicon 84.8 to 89.9 %

Carbon 0. 7 to 0.098 %

Manganese 0.09 to 0.165 %

Phosphorus 0.009 "to 0.015 #

Sulfur 0.005 t> is 0.015 %

Titanium 0.10 to U, 30 #

Copper 0.04 to 10 %

Calcium 0.20 to 0.50 <f>

Nitrogen $ 0.094>

Aluminum. 1.20 to 1.50 <f>

Iron rest

The temperature at the outlet of the molten charge from the cupola should, in order to achieve the best results in the .Bereich of 1472 - 154O ⁰ C (2680 - 28CiO ⁰ F) are kept. When the molten material drips down from the trough 1U into the ladle K, it hits the silicon iron 20 just described. The material 20 is melted so that the silicon in the molten iron goes into solution, while the other additions preferably form a slag, which rises to the surface of the molten metal.

.before the semolina pan K removes the melted filling 14 - 19 * from the Cupola U and the material 20 from the buckets 22 takes on, it is important that the interior of the ladle K is clean and free of is undesirable substances that could contaminate the melt to the detriment of the end product.

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A measuring trioliter 24 is placed above the spout 10 of the cupola, as in Pig. 1 is shown; this will add 70 »8 kg (156 pounds) Heat Generating Silicon Spilled This is also a granulate with a grain size smaller than 202.8 mm (8 in.) sieve fineness. This heat generating material 20 consists:

Silicon 61 %

Aluminum 1.25 %

Calcium 0.50 %

Magnesium. 2.75 S ^

Chile nitrate 13i5O #

Iron rest

The container 24 has a small opening in the bottom through which the material 25 slowly falls into the molten iron flowing below in the trough 10 of the cupola furnace. This flow of the melted Metal may be started before the 70.8 kg (I56 pounds) of the heat-generating silicon 25 brought into the measuring container 24 have been »during the supply of this material 25 through the container opening Then everything flows down into the stream of molten material before the molten filling is completely out of the Cupola has leaked.

The entry of the heat generating material 25 into the molten Metal flow in the trough 10 is caused by a chemical reaction that creates violent currents and strands, the result of the released exothermic liärme accompanies.

While the silicon iron 20 together with the molten iron in the semolina pan K absorbs heat and therefore cools the metal, the heat generating silicon 25 falls into the molten metal flowing in the trough 10 of the cupola and generates Y / poor as before noticed. Both sources 20 and 25 of the silicon supply are felt to be desirable in practice: if the entire silicon requirement were brought into the pouring ladle K at point 20, the entire cooling effect would be too strong, and if everything were in the exothermic l'orm in the Trough 10 would be sprinkled, would

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the exothermic reaction will become too violent. They also revealed Try to add too much silicon in place-20 that not all of the addition went into solution.

Inoculation process at the ötelle shown in FIG

The 2900 kg (64υΟ pounds) heavy iron melt has a temperature within the previously mentioned range of 1472 - 1540 C (268υ 2800 ° i ^|% ) when the main pouring ladle K has finally taken it ο At this point in time, the u-pouring ladle is out of its The slag layer, which is denoted by 29 (Fig. 4) and which has collected on the surface of the metal in the semolina pan, is removed to remove the first position of FIGS. 1 and 2 to the second position of FIG. 4 for the inoculation treatment To enable oxides and other gases to flow out of the melt «The ochlack is also removed in order to create space in the pouring pan for the slag that is produced during the inoculation of the melt.

jüs is extremely important for the best vaccination and other results, that the molten material 28 and. the u-ießpfanne K in Fig. 4 a temperature in the narrower range of 1470 - 1484 0 (2680 27ΟΟ υ ") at the start of vaccination.

the temperature of the metal rises within this range, when the ladle α is transported to the point of FIG. 4, the inoculation can be started immediately. If, however, the 'i' temperature is above 1484 ° ^ (27üO ° ü ^f ), the ladle K is left open long enough to allow cooling to the range of 1472 ⁰ 1487 ° C (268Ü - 27OO ° ü ') to effect. Experience shows that the metal UHiIp cools ⁰ U (5 ° F) per minute. With the help of this fixed measure, the cooling time is chosen each time so that the metal temperature is brought down to the desired range.

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Once such a suitable temperature has been reached, a lid 27 'is attached ^{to the ladle IC of the 5 1} Xg _{0 4} , 3 mm (2 in.) Thick top layer of insulation over it. The lid 27 prevents undesirable loss of the molten metal 28 during the inoculation treatment that now follows.

Jas ietall 28 (Fig * 4) contained in the ladle is now ready for vaccination treatment, τ / ährena the calcium carbide and at the same time other admissions, introduced v / earth.

As shown in Fig. 4, the inoculation device consists of an injection tube 30 which leads down through an opening into the lid 27 of the pouring ladle and ends approximately 381 mm (15 in.) Above the floor of the pouring ladle. The tube itself is made of a carbon material that is resistant to the great heat of the molten metal. In the form shown, it has an inner diameter of 12.7 mm (1/2 in.) And an outer diameter of 508 mm (2nd in _e ). From the top of the tube 30 upwards a flexible or tubular connection 31 leads to a fork 32, the main branch of which connects with a built-in valve 33 to the lower end of an outer vessel or container 34. Within this outer vessel 34, an inner container 35 »^ ^he an isolated, having 34 concentric bottom opening to the outer container, which is a little higher than that of the outer container 34th To prepare for the inoculation process, the inner container 35 mu »31» 7 kg (70 pounds) calcium carbide 37 is filled »The material 37 has a granular character with grain sizes varying between 508 mm (20 in«) and 0 mm oil fineness. It consists of the following chemical components:

Carbon '' 27.95 %

Calcium 59.96 %

Sulfur 0.437 %

Phosphorus 0.0065 #

Calcium oxide (burnt lime) remainder

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On the bottom of the outer container 34 is 9.98 kg (22 pounds) this same calcium carbide material as "at 37 'i * i Also shown in Figure 4 is the outer container, over the lower material 37 ', 21.2 kg (46.5 pounds) of calcium carbide (93 #) and rare Krden 7i ») with an additional 0.8496 kg (1 pound and 14 oz.) of magnesium. This mix is 38 in Fig. 4 denotes.

All three ingredients are grainy. The calcium carbide component of mixture 38 has the same composition as the mixture una 37 * (Fig · 4) · The constituent part of the rare earths of Jäisch has the following composition:

Ceria 52.3 %

Lanthanum oxide 27.3 #

Praseodymium Oxide 5.0 #

Neodymium oxide 14 %

Neutral material 10 - 15% consisting of

üarium Sulfur-el-Magnesium Oxide Silica iron oxide iron

The structure of the containers 34 and 35 just described is shown in FIG the position of FIG. 4 held by a chain 40. Connected to the top of the outer container 34 is a pressure cylinder or a pressure line 41, of which at appropriate times a neutral one compressed gas is introduced. Because of the re-vaccination process, which will be described hereinafter, it is convenient to use nitrogen as the neutral gas. A branch 43 of the main gas line passes some of the compressed gas through a needle valve 44 directly into the Iarpfzuleitung 31 and thus into the injection tube 30. This Derived current keeps the tube 30 always open and ready, the JLalcium carbide material from containers 34 and 35 into the molten one To convey metal in the main ladle K.

The neutral uas in the pressure line 41 is under a constant

ο
maintained at approximately 2.12 kg / cm (30 lbs.per sq.in.) and

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! the needle valve 44 is adjusted so that the pressure in the o υ at approximately "Beren part of the container 34", from 562 to 0.703 kg / cm (8 to 10 sq Ibs.per _o · in.j is jJas is a pressure gauge 39. The pressure at the tip of the outer container 34 is present

inner part of the
also in the upper ^ container 35

in order to begin the inoculation treatment, the otherwise closed valve 33 is opened between the containers 34 and 35 and the Line 31 is arranged «As a result, the calcium carbide 37 flows initially downward out of the inner container 35 and then into the molten metal 28 via the injection tube 30 · thereby the .pressurized gas acts as a carrier. During this part of the vaccination process a valve 45 on the pressure cylinder 42 is set so that the gas from the cylinder with a pressure of 2.12 kg / cm (30 lbs » per sqoin.) o through line 41 at a rate of 3 »68 m / h A gas meter 45 streamed on cylinder 42 (13U cubic feet per hour) is used to measure this amount.

We need approximately 6 minutes from the emptying of the calcium carbide 37 from the inner container 35 i ^{n a} s ^ molten metal 28 in the Giespfanne K. At this point the control valve 45 is adjusted to flow about 5.65 m / h (230 cubic feet per hour). During this part of the inoculation process, the contents of the outer container 34, which is 9.98 kg (22 pounds; Calcium carbide 37 'and 21.2 kg (46.5 pounds) of a LIischung of calcium carbide, oxides, rare ". earths and magnesium 3 ⁸ contains, ο introduced into the melt Ga', further 5 minutes are required to transfer the content ax to cause the outer container into the molten metal. the introduction of the contents of the seed tank has a duration of approximately 12 minutes · Mach completion of the vaccination of the melt with the aforementioned materials, but before <fer removal of Impfgerätes from the s _c hmelze is Pure nitrogen is blown through the melt through the injection tube 30 for a period of time and at such a rate that approximately 0.085-0.1412 tor (3 - 5 cubic feet) of gas enter the melt flow of the injection vehicle for a while after the flow of the injection particles has ceased. This nitrogen flow becomes

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Maintain one to five minutes to achieve the desired results »

Inoculation treatment aims to reduce the sulfur content in the molten metal 28, homogenize and refine the grain structure size of the metal and should at least slightly improve the graphite structure of the Turning carbon into granular form

Without such inoculation, the metal 28 would settle in the ladle K at the point in FIG. 4 is not very common Distinguish gray cast iron with a high silicon content. The resistance to expansion during periodic heating and cooling just described would not be present and therefore the main purpose of the invention would not be achieved φ In addition, the! use of the described Double container 34 and 35 the time for the complete vaccination to be kept within the desired duration of 12 minutes · This is the use of two single containers or two refills a single container during each vaccination process: to draw »An important advantage of the short period of 12 minutes is the! limitation of" heat loss during vaccination to a Vi TTiTnnair bie causes a temperature drop of approximately

90 ⁰ C (1OU ⁰ F) during the inoculation time of 12 minutes If this period were extended, the heat loss and the temperature drop would be correspondingly greater preferred range of 1392 * - 1407 ° C (2510 - 253O ⁰ F) when vaccination has ended,

j-dese inoculation with nitrogen creates a high degree of Vortex in the melt, which serves to reduce the effect of the inoculant to improve the base metal. It was also found that nitrogen is the transformation of a part of the pearlitic Raw material in iron rings around graphite grains and in agglomerated flakes, which are interspersed in the raw material, favorably influenced, iuoh the added nitrogen, the molten metal has its granular or the structure of the

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agglomerated flakes upright for a prolonged period of time and it is now possible to obtain the desired metal structure even if the cooling time is over a few Minutes extended. If nitrogen was not added during a post-inoculation, it was necessary to remove the molten metal during A duration of 10-12 meows to pour into the molds so that the granular structure before it is transformed into graphite flakes to preserve the U-cast iron. One of the addition of nitrogen through a melt subjected to re-inoculation will retain its microstructure for a duration longer than JO minutes .. That is highly desirable because it reduces the scrap that results from improper composition of the melt.

While the main ladle K is at the point of the inoculation of FIG. 4, after the inoculation on the slag layer 29 a further insulating layer 48 (FIG. 5), <üe a thickness of approximately 25.4 mm (1 in.). A suitable Insulating material can be used.

Casting process C Figo 5 and 6)

The thus prepared K ladle is brought together with the molten metal 28 contained therein from the site of Figure "4 to a third or" casting subheading ⁿ in FIG. 5. Here, the ladle is supported by a crane, not shown, of tilting a A metal shield with an asbestos back is placed over the ladle at this point to protect foundry workers from the radiation and to further prevent heat loss.

At the location of Fig. 5, a number of molds M (Fig. 6) for making castings Q (Fig. 7) have been prepared to pour the molten metal from the main ladle K into their pouring openings.

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nas metal is in the usual way in the molds k with the help poured from hand pouring pans H. Each is filled with molten metal as shown in Figure 5 and then closed by hand the molds M failed »

The casting work shown in FIGS. 5, 6 and 7 is for the most part conventional shows to be withheld. An arrangement is preferred which allows the entire contents of the main ladle K to be poured into the provided molds for a period of 20-30 minutes 1392 - 1407 ° C (2510 - 2530 ^O i ') lie This l'emperature remains experience has shown that during the casting operation.' iatsächlich that is the Hauptgießpfanne K extracted metal 28 when it is only partially emptied, a little warmer than that when it is completely full or almost empty.

.jie much better quality of the castings

As mentioned earlier, the castings y and solidification can be taken from the molds M of Fig. 6, the same Dimensions like the molds in which they were cast. It is particularly difficult for such original permits to be preserved to explain. However, such a result is realized and educated an advantageous characteristic of the new cast iron.

with the previously described "resistance to volume increase paired under repeated temperature periods outside of wide areas, makes the new cast iron highly attractive for applications like z, i>. for grate supports for furnaces, in

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Tubes of steam boilers and other heat-exchanging systems and the like. The comparatively high silicon content denotes Material brings about an advantageous' resistance to corrosion, ojie high tensile strength of the material (4220 Kg / cm (60000 pounds per sq.in. and more)) increases its practicality Possible application.

Significant reduction in scrap

jj ± e new cast iron alloy, which is made on the new Y / eg · described here, has the important part of the goal of being relatively free of scrap losses under the end castings Q. These losses can easily be kept below 5 / &, and can even be can be reduced to 2% if the various "controls * of the production process already described are strictly adhered to.

xde great reduction of the committee is due to both the feed the nitrogen pour (as mentioned earlier) as well as the additive traced back the üiliziums in the ü-ießpfanne K (Fig. 2).

It has been shown that the addition of the silicon prior to the inoculation treatment with calcium carbide (shown in Fig. 4) is far better than adding any amount of silicon after this vaccination is done. Bolch a re-vaccination with even a few silicon grains tend to create a gaseous metal, its In the mold M ascending ± slasen Gub pieces 14 produce, the grass pores and have other errors. This one cause of gaseous metal has been corrected in accordance with the invention by restricting all silicon additions to the molten metal filling before inoculating that metal with calcium potassium (Fig. 4) was made. This advantageous result of the pre-inoculation with an addition of silicon is surprising, since it is precisely In contrast to the usual over-the-top experience and the teachings of

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Gangenheit stands «which is why the invention represents a practical one Port step of a high degree »

Even if all the silicon is added before the inoculation treatment (Fig. 4), it is also found that the metal that is in the molds M of the Pig. 6 is poured, again has gaseous character traits when the melted filling 14-19 äer Pig. · 1 is subtracted from the cupola C at a temperature above 154O ° G (2800 ⁰ P) In these conditions, the castings ^ of Pig. 6 and 7 again gas pores and other defects due to the rise of gas bubbles in the molten metal 28 as it is poured into the molds M from the pans H and K. Therefore, it is important in the production of the cast iron alloy, the molten filling 14 - 19 & ^ex Figo 1 (F 2800 ⁰⁾ is subtracted from the cupola C at a temperature below ⁰ C 154U. Experiments have shown that the temperature of the withdrawn metal can be brought down to 1472 ° u (268O ⁰ J! ') In order to enable a satisfactory "sequence of the production process shown in FIGS. 1-7". This is followed by the range mentioned earlier of 1472-154O ⁰ C (2680-2800 ° P). If the metal is withdrawn below 1472 ⁰ O (2680 ⁰ P), the molten metal can cool down too much before it is poured into the casting molds M of FIG and that is the reason that set the lower limit

The inoculation at the location of Fig. 4 is another factor in the production process, because of which the temperature conditions described must be carefully observed, ΰο it was determined that the relatively narrow temperature range of 1472 - 1487 ° u (2680 -

P) , in which the temperature of the molten metal 28 in the pouring ladle K at the start of the pouring process, should be maintained as precisely as possible. The lower temperature limit is given by the fact that the metal 28 is still hot enough during casting (FIGS. 5 and 6).

First, the metal should not have any after being transported to the casting site t have excess temperature so that no shrinkage of the castings occurs.

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This is partly due to the size of the cast cones and the vertical sifter reached the mold M, but for molds of normal size and usual structure could be found that the casting the cast iron alloy is best at temperatures that 1389 C (2530 °]?) Is not exceeded. ■.

various controls of both temperature and the Time is therefore an essential part of the manufacturing process. according to Fig. 1-7 »because the critical factors mentioned above must be taken into account. "

Production control summary

"Dm the ones used in the improved production process and here To summarize the controls described above, the melted mill should be 14-19 'at a temperature in the range of 1472-150 ° C (268O - 28uO F) can be withdrawn from cupola C of FIG. At the start of the inoculation treatment according to FIG. 4, the molten Metal 28 in the ladle K have a temperature in the range of 1472-1487 ° C (268Ü - 27üO ° F). Separate this from the ladle K in 2 is initially too hot, it should be at least 1487 ° C (27 ° F) before the start of the inoculation according to FIG. let cool down.

Then, the seeding treatment should itself in FIG. 4 was carried out within 12 minutes, the accompanying drop in temperature so that the metal 28 to approximately 288 ⁰ C (Ι6ϋ ° ϊ) is limited, "A larger temperature drop from said ladle K to the casting station from. Fig. 5 Let transported metal get too cold. Any minor temperature drop will cause a waiting or cool-down time that will affect the quality of the metal. If the metal is poured too hot, the tendency to shrink in the mold M is correspondingly higher.

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Claims (1)

Request a patient Process for the production of cast steel., The coal partly in granular Form, and contains other additives, as they are customary for the production of gray cast iron, characterized in that the melt after the fume cupboard are first of all added high silicon additives, then the melt is subjected to an inoculation process with calcium carbide and rarely Earth for the purpose is subjected to the sulfur content to reduce, to refine the grain size of the oil and at least to convert part of the coal from the flaky to the granular form, and that finally the melt obtained in this way is poured into a mold " Method according to claim 1, characterized in that an inert G-as into the molten metal simultaneously with the inoculation with valcium carbide, magnesium and rare earths is introduced, and that the supply of the inert gas after ± seenaigung the inoculation process is continued. 3. The method according to claim 1 or 2, characterized in that a ! Mixture of calcium carbide, magnesium and rare earth elements in the melt is inserted with the help of a tube which is inserted into the melt immersed, and that the inert ü-as is also fed through this pipe will. 4. Method according to one of the preceding claims, characterized in that that the introduced into the melt after the inoculation process Gas is nitrogen. 5. Method according to one of the preceding claims, characterized in that the melt is kept at a temperature between 1470 - 1484 ° C (2680 - 2700 ⁰ I- ') during the inoculation process » 809810/0620 6. Process according to one of the preceding claims, characterized in that the melt is removed from the furnace at a temperature between 1472-154O ⁰ G (2680-28 <10 ° -b ^l ), and that in this temperature range the high-silicon additives are supplied, and that only then is the vaccination process carried out. 7β method according to claim 6, characterized in that during the withdrawal of the melt a certain amount of exothermic silicon is fed, that then the metal treated in this way is poured into a container containing a certain amount of ferrosilicon contains, and that then the melt is inoculated with calcium carbide, magnesium and rare earths. 8ο Method according to one of the preceding claims, characterized in that that the supply of the inert gas continues for one to five minutes after the vaccination process has ended. S>. Method according to one of the preceding claims, characterized in that the inoculation process lasts about 12 minutes and is accompanied by a temperature drop in the melt of 90 ^ (I6u i ¹ '). 809810/0620