DE2828327A1 - STUBBLE MANUFACTURING PROCESS - Google Patents

Description

1. Tsentralny Nauchno-Issledovatelsky Institute Chernoi Metallurgii imeni I. P. Bardina

2. Donetsky Politekhnichesky Institute

STICK MANUFACTURING PROCESS

The present invention relates to metallurgy, in particular to a process for the production of billets for subsequent processing in "shaped steel and tubular mills".

The present invention can be used in the unification or combination of the continuous casting with the rolling in the Manufacture of billets from high-alloy steels and alloys, to be applied to the greatest advantage.

The practice of producing billets has shown that in recent years there has been a tendency towards the production of semi-finished products by continuous casting. With good structural stability and chemical homogeneity of the ingot

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lengthways there is a clear secondary cavity and segregation zone of chemical elements in the cross-section of the billet. There are currently no sufficiently effective methods of acting on the metal in the continuous casting process that are able to eliminate the axial segregation. The quality of the central part of the

Knüppels in the manufacture of products, their 'operational characteristics are dependent on the degree of development of the axial segregation, e.g. in the manufacture of ball bearing, Tool, corrosion-resistant steels and the like,

The presence of the axial segregation in the finished profile steel of high-alloy tool steels does not offer the possibility of _{delivering it according to the} order, where the macrostructure and microstructure are checked, in particular because of the carbidic inhomogeneity. The uneven distribution of carbon and alloying elements in the finished product results in uneven distribution of the carbide phase. The operational characteristics of the finished product are determined by the local accumulation of carbides and

the carbidic strip structure deteriorated significantly. Since the cutting edges of the tools break off when the carbide strip structure is present, their service life is increased shorter.

At the same time, continuous casting is much more economical than other billet manufacturing processes. The development of a new billet manufacturing process that

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the billet without macro-shrinkage errors and, as a consequence, an extension of the service life and a safety

simultaneous

of the finished products with ν lower costs guaranteed, therefore represents a current problem for stainless steel manufacturers and consumers.

A billet manufacturing process for

products that are still in use that are completely homogeneous

the

and require dense metal. For this purpose, an ingot is irfKokille poured, then rolled and scooped in a rolling mill for heavy semi-finished products.

At this time, the size of the tail drop exceeds 20% and it

there are additional costs associated with processing the receipt

to the

blocks ^v billets are connected. The prime costs of the finished products are therefore extremely high.

For more responsible orders takes place in world practice the electroslag remelting process is widely used .. However, the cost increases in this case compared to the production according to the above described variant by 2 to 2.5 times. Widespread is a process for making billets that are necessary for responsible jobs, the one in disposal the clear .. secondary slump and segregation zone in machine tools for machining. Of the fiohblock is divided into two or four parts along the longitudinal axis cut up, of which afterwards the axial segregation zone removed by planing. A variation of this process

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is used in the manufacture of hollow bodies such as high-pressure vessels Use·

In this case, the axial block part is drilled out and the blook is then subjected to a mandrel deformation. By mechanical removal of the secondary cavities and those accompanying them Segregation is naturally the finished product ion considerably more expensive.

A continuous casting process in which the cast billet is deformed with a liquid core is more progressive (see, for example, Federal Patent No. I 220 973, filed in 1961, IEK class ² B22D).

Disadvantages of the solutions described and similar are the deterioration in quality of the billet to be produced depending on the pouring as a result of an increase in concentration of Segregation elements as well as discontinuity errors that occur in Blocking occur in the two-phase state.

A method for improving quality of finished rolling, _a n ch is known to to give delimits a Bohbramme in calibres with a number of sipes is rolled, the segregation zone in the central stick. The hand sticks are free of segregation (see, for example, Federal Patent No. 805 154, filed in 1948, Class 7a, Group I).

However, this scheme for the production of high-quality billets produces a very high level of metal waste, around 33%, because the middle billet is only suitable for remelting.

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A method of making ronlings has found limited use for cutting tool used in casting a hollow block with a rectangular cross-section with an aspect ratio of 1: 2, which is then cut lengthways into two equal parts. Each of the two halves of the new block is then subjected to non-cutting shaping.

One disadvantage of the known method is its high cost due to poor cutting performance and considerable metal loss (see e.g. FR patent specification No. I 489 187, registered in 1966, class B2IB).

Multi-line and multi-beam systems are well known (see e.g. Germann B. "Der Strangguß" / "Nepreryvnoe litie" /, Moscow, "Metallurgizdat", I96I / Translation from German /, Pp. 155 to 154, Figs. 441 to 445). When pouring in a Kokile of this type are separated from each other and boards connected to the common central block part shaped. In the cross-section there is a completely star-shaped one Block.

However, the size of the waste (central part) over 15% of the block weight, and there is no guarantee for the flawlessness of the billet beams (legs).

A mold is known which contains cooling walls which form a working cavity with a star-shaped profile. When casting in this mold, a complete block with a star-shaped cross-section and central symmetry relative to the central axis is created (see, for example, SU copyright certificate no. 226 796,

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Class B22D 11/04, 1965).

A disadvantage of the known design is above all the formation of such a raw block, when it is separated into Billet there is a reduced yield of usable billets without an axial zone error. Considering that the width of the base of each part of the mold cavity at the joints with other parts is greater than the opposite base, the longitudinal separation of the beam from the block is difficult and from accompanied by a large loss of metal. In this process, the yield of usable billets is good. Shrinkage-related Macro error not more than 70%

It is the purpose of the present invention to eliminate the drawbacks mentioned above.

The invention is based on the object of an economical To develop methods of manufacturing billets free of macro-defects of void origin.

This object is achieved in that comprises in a billet manufacturing method which comprises generating e ^ symmetry ines complete ingot with a star-shaped cross-section and central, _ relative to the central longitudinal axis of the entire ingot, according to the invention, the segregation zone is led out of the rays of the complete Rohblooks , whereby the segregation zone is delimited in the central part of the complete ingot and then the rays of the complete ingot are separated from the central part.

1 ** 163/083?

When this process is carried out, secondary cavities will appear and the accompanying segregation zone in the Blasting the entire ingot eliminated.

It is preferable to create a complete Eohblock,

which has a star shape in cross section with at least two

each has len, with a base ^ of the rays of the complete Sohbloeks in the connection zone with the central one Part of the complete ingot 0.72 to 2.3 and the two

the

te foot is 0.5 to I, O ^v beam height.

In this lall, the delimitation of the segregation zone in the central part of the entire raw block is assured. There is practically no segregation of chemical elements in the cross-section of the rays. Apart from that, the non-pre-eminence leads
presence of secondary voids in ^v rays in the case of using the method according to the invention to reduce the minimum required decrease in the billet, in other words to abolish the rolling processing in billet

e
Rolling mills. In addition, this process offers the possibility of reducing the number of continuous casting plants by a factor of two because of the increase in their performance (cross-sectional area).

It is advisable to produce a complete ingot with a star-shaped cross-section, with one of the flanks 3 to 15% longer for each beam of the complete ingot than the other must be.

This shape of the complete ingot offers the possibility of measuring the quality of the rays at the points of their separation.

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from the central part by eliminating the need to turn the To improve rays at their separation.

In accordance with one of the implementation variants of the invention are the beams of the complete ingot with a star-shaped cross-section at the same time separated from the central part.

At the same time, the expenses associated with the separation are completely eliminated by reducing the number and the Steel requirements of the continuous casters made up for.

After another. Implementation variant of the invention are initially two beams from the complete ingot with a star-shaped cross-section with three beams and then the central part separated from the rest of the beam.

This beam separation scheme offers the opportunity to intensify the separation process.

In a number of cases it proves favorable to the rays by the action of a

respectively
Roll caliber to separate the flanks of the beam from the central part of the complete ingot one after the other.

There is the possibility of

existing rolling mills without their redesign

to take advantage of what significantly reduces the effort required to separate the rays.

When the shift direction after the shift

that of the beam by a magnitude of 0.57 to 0.92 ^v beam height

is changed to the opposite, the upper

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surface quality of the rays at the points of their separation from the central part better.

It is useful to create a T-profile from the complete ingot with a star-shaped cross-section with three beams to shape, then to separate from this two opposing rays, being relative to the rest Part of the profile to be moved, after which the central part of the complete ingot is separated from the remaining beam.

This makes it possible to increase the rolling mill output when separating the beams from the complete ingot.

In some cases it is very beneficial

if first two opposing beams are pushed in the rollers from the complete Raw block with a star-shaped cross-section with four rays and then the two remaining rays from the central one Part to be separated.

That offers the possibility of sticking out more regularly geometric shape with a high rolling mill output.

It is useful to have a complete ingot with a star-shaped cross-section with four rays with a ratio the axial dimensions of the mutually perpendicular rays of 1.05 to 1.5 establish and simultaneously with the separation of the two opposing beams to pre-block the rest of the block part from a lower height, whereby smaller rays with a cross-sectional area that is around

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1.05 to 1.5 times larger than the cross-sectional area the billets to be made from these beams.

The yield of usable high-quality billets is increased and the process of beam separation is simplified.

It is advisable to create an unfinished ingot with a rectangular cross-section before producing the complete ingot continuously cast with an aspect ratio of 1.0 to 1.8, of which in the rollers a complete ingot with a star-shaped cross-section with four beams with one beam height the

from under I / 3 ^V side of the ingot to be poured and a ratio of the axial dimensions of the opposing beams of 1.0 to 2.8 and then separating the beams from the central part of the complete ingot.

In this case, the continuous casting process is simplified and the billets can be discharged without any macro-defects of segregation character elevated.

According to another implementation variant of the invention, each of the beams after taking out the segregation zone from the rays of the entire ingot by 10 to 30% in a direction perpendicular to the radius of the beam direction _y deformed whereby the segregation zone by simultaneous forming with the beam blooming process of the central part of the complete ingot is introduced into the beam, after which the beams with a height ranging from 1.02 to 1.5faohea of

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the starting height is to be separated.

In this case, the process of separating rays from the central part of the complete ingot is significantly simplified.

The next implementation variant offers the possibility of spreading on billets with guaranteed quality of the Increase macrostructure. This is achieved in that the complete raw block with a star-shaped cross-section with two Blasting is generated from a continuously cast slab with an aspect ratio of 1.05 to 2.0, for which purpose the slab in the segregation concentration zone is rolled down, wherein

ei ~ T

If the segregation zone by Oji ^ Bramraendicke strong and 0.4 to 0.7 ^v slab thickness in the central wide part delimits 0.3, and then the rays of the entire ingot to be separated from the central part.

It is desirable to have the rays of the complete ingot separated from the central part at a temperature of the means
tails from 0.37 to 0.48 ^v melting point of the metal, with the rays being shifted by 40 to 65% relative to their starting position.

The process of radiation separation is intensified with this heat transfer.

A similar effect can be achieved if there is a build-up of stress leading cross cuts e.g. 0.07

the

Up to 0.2 ^v beam height deep and 0.02 to 0.1 beam height wide notches before the separation of the beams of the complete ingot from the central part at the connection points of the

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Rays are formed.

The invention is explained below with the aid of implementation examples, explained in more detail with reference to the accompanying drawings. Bs shows:

Fig. I a cross section through the complete ingot with a star-shaped cross-section with three rays,

Pig. 2 the shearing of one jet from the complete Hollow block in the rollers in side view;

Pig. 3 the section along the line

II in Pig. 2;

Pig. 4, 5 the rolling stock cross-section in the stage according to FIG. and a further stage of beam separation;

Pig. 6 a diagram of the separation of the beams of the complete fiohblock using the counter thrust,

Pig. 7 shows a diagram of the separation of the rays from the complete Raw block after one of the beams has already been separated,

Pig. 8 the same, but with thrust in the opposite direction,

Pig. 9, IO a scheme of the final separation of the rays from the core,

Pig. 11 after separating the complete ingot. preserved billets,

Pig. 12 a cross section through the complete ingot with different lengths of the planks of the beams,

Pig. IJt a scheme of separating the rays from that in Pig. 12 complete ingot shown,

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14, 15 a diagram of the formation from the complete Ingot with three beams with T-shaped cross-section,

Figures 16-18 are a schematic of simultaneous separation the rays from the complete ingot with three rays,

19 to 21 a diagram of the separation of the central Part of the rays of the complete ingot,

22 shows a cross section through the complete ingot with four rays,

23 to 25 a diagram of the separation of the beams from the Raw block with four rays,

26 to 28 a diagram of the separation of the central Part of the rays after the separation of two rays,

29 billets obtained after the separation of the complete ingot with four beams,

30 shows a cross section through the complete ingot with different rays,

Figures 31 through 33 are a diagram showing the separation of the beams from the ingot shown in Fig.

Figures 34-36 show a diagram of the separation of the remaining ones Rays from the central part,

37 billets made from the complete ingot,

38 shows a cross section through the complete ingot with four rays,

39 to 41 a diagram of the separation of the rays from the central part of the complete ingot,

Ίί> ·

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42 shows a block cross-section,

43 to 45 a diagram of the formation of a cruciform complete ingots,

Fig. 46, 47 a diagram of the beam separation,

48 shows a diagram of the separation of the remaining rays from the central part,

49 is a diagram of the final beam separation,

Fig. 50-51 is a diagram of the extension of the rays of the complete ingot by introducing the segregation zone in the rays,

Fig. 52, 53 a diagram of the separation of the beams from the complete ingot with three beams, 54 shows a cross section through the raw slab,

Fig. 3ϊ> to 57 a scheme of the formation of the complete drilling block,

5 ^{8 shows} a cross section through the complete ingot with cross-sectional incisions leading to stress accumulations.

I ^ a continuous caster is a complete ingot I (Fig.I) cast. Conventionally, it can be made up of several parts u.z. from legs 2, 3 »4 and a central part 5 consisting of represent. In other words, the raw block I has a star shape in cross section with several, in the present case three beams 2, 3 and 4 connected to the central part 5 are. The rays 2, 3 and 4 are symmetrical, relative arranged to the center of the complete ingot I i.e. the angles between the flanks of rays 2 and

* hereinafter referred to as "rays" throughout

3, 3 and 4, 4 and 2 are the same as each other. The separation of the segregation zone 6 from the beams 2, 3 and 4 and its delimitation in the central part 5 of the complete ingot I is achieved primarily by the selection of the size ratio of the complete ingot I. If each of the beams 2, 3, 4 in the zone of connection with the central part 5 of a base "c" has having the 0.72 to 2.3 times ^v height "a" of the beam 2,3,4, wherein the second base area "b ·· of the rays 2, 314, which is 0.5 to 1. Of the height of the ray" a ", the rays 2, 3» 4 have no shrinkage and segregation errors in the axial zone. With the separation of the beams 2, 31 4- from the central part 5, the size of the waste associated with the return of the central part 5 for remelting decreases significantly , reached 90%.

With a base "c" of rays 2, 3 and 4 in the zone of their connection with the central part 5 from below 0.72 beam height (c / a <0.72) is like experiments

ζβη showed that the occurrence of secondary cavities and segregation 'in the axial zone of rays 2, 3 _f 4 · possible. On the other hand, is the base "c" of rays 2, 3, 4 in the zone

that of their connection with the central part 5 ₍ greater than 2.3 ^v height "a" of the beams 2, 3 »4 (c / a> 2, 3), the discharge of usable billets without defects in the axial zone is less than 75%. If the base area "b" of rays 2, 3,

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less than ^ the height of which, then in the axial zone of rays 2, 3, 4, shrinkage defects and sections with accumulation of segregation occur due to bridging during crystallization between rays 2, 3 »4 and the central part 5. With a base area "b" of the beams 2, 3, 4 of more than 1.0 height "a ^{M of} these beams (b / a> 1.0), the discharge of usable billets goes back to a level of less than 80%, with the metal waste during the separation of the beams 2, 3, 4 from the central part 5 of the complete ingot I increases.

When forming the complete ingot with a three-beam cross-sectional shape with a ratio of the dimensions c / a = 0.72 and b / a = 0.72 in a mold is the yield of usable billets after the radiation separation 90.6%.

A particular difficulty in billet production is the problem of separating the beams from the central part of the complete ingot. The beam separation in the rollers of a voting machine has proven to be extremely effective. In this pail a complete strand I is cast in a continuous caster, the segregation zone being concentrated in the central part 3 , and the beams 2, 3, 4- show no defects in the axial zone. After casting, the strand I is cut to length, preheated to the rolling temperature and fed to the rolling train. In the rolls 7 and 8 (Fig. 2) of the rolling mill, the beam 2 is opposite the beams 3 and 4 and the central part 3

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(Fig. 3). · The offset of the beam 2 takes place by pre-rolling the flank of beam 2 with the caliber of roller 7. The beams 5 and 4-

as well as the central part 5 before displacement in the vertical plane held back by rollers 7 and 8. The size of the one-time displacement of the beam 2

the

when it is separated from the central part 3, it is

the

speed of the rolling mill parts and ^v gripping conditions of the rolls 7 and 8 given. During further rolling (FIGS. 4 and 5) the jet 2 is completely detached from the central part 5 (FIGS. 4, 5) under the influence of the upsetting surface of the caliber of the roller 7 (FIG. 3). However, it is more appropriate to change the direction of displacement in the opposite direction, as shown in FIG. 6, after the beam 2 has been sheared by an amount of 0.57 to 0.92 beam height. When the swaging and therefore the sliding surface of the caliber previously belonged to a roller, it is now part ² ^ r opposite. In this case, the energy force parameters of the separation rolling process decrease, the angles of the beams to be separated are rounded and the base area of the beam on which the separation took place is of higher quality. The best position for beam separation is when the flank of the beam to be burned is parallel to the roller axis. After the separation of the beam 2 from the central part 5, the pre-rolled rolled product is therefore turned by 120 ° about the longitudinal axis. Furthermore, the beam 3 is made by pre-rolling the

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Beam 3 (Pig. 7) with the caliber of the roller 9 separated from the central part 5 (Pig. 8). Then the beam 4 (Pig.9) is separated from the central part 5 in a similar way (Pig.10). As a result of the process technology described above, three billets 10, 11 and 12 (Pig. II) free of shrinkage macro defects are produced, which are used for further processing into highly stressed Pertiger products. During the beam separation, the central part 13 is also formed with segregation enrichments, which is passed into a steel smelter for remelting.

When the beams of the complete billet are separated in the rollers of a rolling mill, a complete strand is formed on the continuous caster, which has a three-beam profile in cross section. The rays of the complete strand are free from shrinkage macro-defects. The length of the planks differs from each of the rays at the ends of their base areas by 3 to 15%. A ratio of 1.03 to 1.15 between the lengths of the planks of the beams offers the possibility of concentrating the segregation zone in the central part of the complete strand and at the same time simplifies the process of beam separation because it prevents the beam to be separated from turning in the roller caliber will.

The complete strand with rays 14, 15, 16 (Pig. 12) is fed to the rolling train, where the beams 14, 15, 16 be separated from the central part. ^ 1.7 of the complete strand. Each beam 14, 15, 16 is in cross section in the shape of a

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<it
^

<it
Right-angled trapezoid ^ with an ^{equal base n} c "in the zone of connection with the central part 17. The other base of the beams 14, 15, 16 is also equal to" c ", and the planks of the beams 14, 15, 16 are perpendicular to the base in the zone of connection with other rays. One of the flanks of the rays 14, 15, 16 is equal to "a", the other "a" + Ah, where Ah is 3 to 15% of "a" Separation in the rolls 18 and 19 (^ ig · 13) of a two-high rolling mill stand due to the difference in length between the flanks of the beam 14 forces occur which prevent a turning of the beam 14 to be separated from the central part 17. This eliminates the distortion of the beam and conditions for the pure shear when the beam 14 is displaced relative to the central part 17 is created.

Bs is easier to make the rays from the complete strand of a three-ray star cross-sectional shape Separate, if an ingot of T-shaped cross-section is made from it beforehand is shaped. For this purpose, a complete strand cast with three rays. When doing the base of the beam in the zone of connection with the central part 0.72 to 2.3 beam height and the other The base area of the beam is 0.5 to 1.0 beam height, so the whole segregation zone becomes in the central part of the complete Strand localized. The rays 20, 21, 22 of the complete strand are secondary cavities and, what is

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is bound, segregation-free, and the metal is tight here and homogeneous. In the rolling mill, the jets 20 and 21 (! "Figs. 14 and 15) in the first and second pass are relative turned towards the beam 22 until the flanks of the beams 20 and 21 are perpendicular to the rolls of the rolling mill. In the next stitch, the rays 20 and 21 are shifted simultaneously by moving them relative to the central part 25 can be moved. The flanks of the beams 20 and 21 (FIG. 16) coincide with the boundary surface of the roller caliber pre-rolled and de ;. ' Beam 22 and the central part 23 secured against vertical displacement. After that, will the amount of mutual displacement of the opposing rays 20 and 21 relative to the central part 23 increased (Fig. 17). By pre-rolling the flanks of the beams 20 and 21 (Fig. 18), which are the originally to be pre-rolled are opposite, the rays 20 and 21 are finally separated from the central part 23 in the next stitch. Thereupon the rough rolled product is rotated 90 ° and the beam 22 (Figs. 19 to 21) is similar to that described above separated from the middle part 23. The yield at. usable high quality billets is not less than 87.5%.

In a number of cases, e.g. in the absence of forming equipment, the simultaneous separation proves to be the case of the rays of the complete Eohblock from its central part as effective. For this purpose, the complete raw block with a star-shaped tyuersGimitt with three equal and symmetrical arranged beams with scarfing machines in the longitudinal direction

the base of the rays in the zone of connection with the central part separated, whereby the rays from the separated in the middle. Using autogenic ! "eyecatchers and laser cutting torches, impulse cutting, The beams of the entire hollow block can be sawed and the like at the same time separate from the central part.

The separation of the rays from the complete ingot with a star-shaped cross-section with three beams is by necessity of the veneer a Sonderwal ζ armature ER- schw ^e3rt and requires a complicated design of the rollers for separation rollers. In continuous rolling mills, the use of a complete strand with four beams is preferred.

The complete strand with a star-shaped cross-section with four rays is ⁱⁿ . cast in a continuous caster.

If a symmetrical complete line with four beams

the
len with a 0.72 to 2.3 ^v 'beam height equal base area

of each of the rays in the zone of communication with the

the central part and with a second 0.5 to!, Ο ** ray height

If the same base area is poured, then there are secondary lunts ker and accompanying segregation> in the central part

urged, which is the last to crystallize.

This line can conventionally be divided into five sections

be horny, namely: in the central part 24 (Fig. 22)

with segregation zone, which arises in the crystallization process, and in four free from segregation and cavities

'ν. ι '

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Rays 25, 26, 2? and 28. The central strand part is separated as follows. The rollers 29 and 30 (FIG. 23) form, with caliber incisions, a caliber in which a deformation of the cross-shaped strand occurs. Displacement of the beams 26 and 28 relative to the remaining part of the rough rolled product takes place. The further displacement of the beams 26 and 28 takes place in the next caliber formed by the rollers 31 and 32 (FIG. 24). The successive displacement is carried out in such a way that the beams 26 and 28 are not separated from the remaining part of the rough rolled product. The final separation of the beams 26 and 28 (IFig. 25) takes place in the rollers by means of their displacement in a direction opposite to the displacement in the previous gauges. The remaining part of the rough rolled product is rolled together with the central part 24 and the jets 25 and 27 in a pass formed by the rolls 33 (FIG. 26), while the central part 24 is displaced relative to the jets 25 and 27. The further shifting takes place in gauges similar to that shown in Fig. 27 without the parts of the rough rolled product being brought to complete separation. Then the gauges are rolled, where the central part 24 is displaced in the opposite direction until the beams 25 and 27 are separated from the central part 24 (FIG. 28). As a result, five individual billets 34, 35 »36, 37, 38 (Fig. 29) are produced, ^< ^ ex \ vpn those which do not have a segregation zone, and

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a billet 36 with segregation zone can be used for production used by little-used products or for. Remelting are conducted

When using the complete strand with four jets, the application can be carried out on usable billets increase as follows. A complete strand is cast. Taking into account the best parameters of the continuous casting process and geometric proportions of the rays 39 »40» 41 and 42 (Fig. 30) and the central part 43 is the Segregation zone in the central part 43 of the complete strand localized. In doing so, a zone of dense and homogeneous metal is formed at the boundary of the joint of each of the Rays 39, 40, 41, 42 with the central part 43 out. the Rays 39 and 41 are 1.05 to 1.5 times larger than the rays 40 and 42, the height ratio of the mutually perpendicular rays is 1.0 to 1.5. ■ The rays 39, 40, 41 and 42 are in the following sequence separated from the central part 43. With the rollers of a rolling mill, the beams 39 and 41 are simultaneously Displacement of beams 40 and 42 (Pig. 31) relative to the remaining part of the rough rolled product rolled down. Pig. 32 shows one of the intermediate phases of separating rolling. Here, the deformation mode is selected so that that there is no separation of the beams 40 and 42 from the remainder of the rough rolled product. The separation takes place in the caliber (Pig. 33), where the rays 39 and 41 simultaneously with the counter-thrust of the rays

40 and 42 are finally here to be rolled. This rolling scheme allows the central part 43 to be deformed compress and its cross-sectional area compared to that original to zoom out. Then the separation rolling of the beams 39 and 41 (Figs. 34 to 36) is carried out, which takes place by displacement and subsequent counter-displacement relative to the central part 43. From all separate parts 44, 45, 46, 47i 48 of the complete strand (Jig. 37) are four parts 44, 45, 47 and 48 suitable for further rolling the billets.

A similar effect can be obtained as follows. A cross-shaped strand with the central part 49 (Fig. 38) and four beams 50, 51, 52, 53 is cast in a continuous casting machine. The beams 50 and 51 are formed so that the cross-sectional area i ¹ ^ of each of them is 1.05 to 1.5 times larger than the cross-sectional area F _{2 of} the billet produced from the beams 50 and 51 after the separation rolling. The change in the cross-sectional area of the rays is essentially made by changing the size C compared to C ₂ . The range of change in the size ratio H / h si, 05 to 1.5 is conditioned by the following boundary conditions. The lower limit of 1.05 was based on the required size of the height adjustment. ... FormuBgsgradee of the vertical element of the complete strand selected during the rolling process, the vertical deformation'aich results from the reaction of the metal to forces that cause shear deformation of the beams 50 and

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which are expended. In its final phase y is going into a shift Shear over, and the minimum degree of deformation is within 1.1 to 1.05. The upper limit of 1.5 of the area ratio is due to the crystallization condition of the complete strand limited. When the rays 50 and 51 are separated (FIGS. 59 to 41) they deform in the direction the reduction of the base areas, whereby their cross-sectional area becomes smaller.

In those babble if it is expedient to i _n a continuous casting machine to be cast billet to unify in a comprehensive steel grade composition of the strand is cast 5 ^ (FIG · 42) having a rectangular cross-section and an aspect ratio of 1.0 to 1.8 . The secondary lunker and related segregation ¹ of chemical elements is concentrated in the central part of the strand 54. In cross section, the segregation zone 55 has the shape of an ellipse, the axis ratio of which depends on the aspect ratio of the strand 54 to be cast. With an aspect ratio of the strand 54 to be cast within 1.0 to 1.8, the segregation zone, as theoretical calculations and practice have shown, has the shape of an ellipse or a circle with an area that does not exceed

the
6 to 10 $ cross-sectional area of the strand. When casting the strand with a square cross-section, the segregation zone in the Hegel has a shape that is close to a circle whose diameter 1/3 side of the strand is not

exceeds. With strict adherence to the casting process parameters If the segregation does not go beyond the scope of the permitted steel grade composition, its

the

however, its presence worsens mechanical properties of the steel, the grain size increases and the inhomogeneity of the structure increases. In a number of cases e.g. in the production of billets from ball bearing and other steels with a functionally important purpose, the Formation of a flawless central zone of the billets where there is no segregation zone, the main problem because it affects the operational characteristics of the finished product significantly influenced.

The question of the complete elimination of the segregation zone in the casting process has not yet been resolved. It therefore seems expedient to eliminate the segregation zone in the subsequent processing. For this purpose, a cross-shaped profile 56 is formed from the strand 54 in several stitches (FIGS. 43 to 45). The shaping takes place in the rolls of a rolling mill, for example a two-way reversing block mill. The segregation zone 3 ^ is located in the central part of the cruciform ingot 56.

During the formation of the cruciform ingot 56 are the horizontal jets (sections to be pre-rolled) are divided into sections by a flow disk, which are at the center Block part. As a result of transverse displacements, the metal overflows into the central part of the block. This will make the

the

Segregation zone 55 contracted according to width. With consideration on ι that all elements of the raw block have a common stretch coefficient and that a longitudinal and Cross-interaction between them comes about, the portion of the cross-sectional area of the rough block remains, which the Seiger ung assumes constant during the formation of the cruciform ingot 56. Will be the complete hollow block without periodic Rotation formed around the longitudinal axis, the length ratio of the mutually perpendicular rays 2.8 achieve what the unification of the manufactured Stick in the way. It is useful to make the cross-shaped profile with periodic rotation of the rough rolled product to form 90 °, which compensates for the length of each other perpendicular rays leads.

The length of the segregation zone increases with the Increase in elongation. The base of the rays therefore becomes smaller in advance than the width of the segregation zone Starting block taken. In view of the fact that the stretching in the standardization of the cruciform ingot within 1.5 to 2.0 fluctuates, the base area is within:

a - (0.5 to 0.9) D.
chosen, where

a height of the base of the beam,
D is the diameter of the segregation zone in the starting block.

The cruciform ingot that is produced is rolled in the rolls of a rolling mill, initially two of which are each other

opposing rays (Figs. 46 and 47) can be shifted until they are completely separated. After that, that will Pre-rolled rolled product turned by 90 ° and the two remaining beams separated from the central part 48 and 49).

As a result of the sequence of operations mentioned, there is a minimal amount of metal waste when the segregation zone is disposed of guaranteed. The waste size is practically of that Shape and dimensions of the segregation zone in the starting block addicted.

When separating the jets from the complete ingot with three jets in the rolling mills, the following procedure proves to be effective: the jets 57 »58 and 59 (Figs Beams 571 58 and 59 are applied, rolled down by 10 to J> 0%. As a result of the rough rolling, the base areas of the jets 57 »58, 59 become smaller, with the metal of the central part 60 migrating into the jets 57» 58, 59 with accumulations of segregation. The size of the penetration of the segregation zone into the rays 571 58, 59 depends on the length of the sections of the central part 60 which are deformed simultaneously with the rays ^ ₁ 58, 59, and on the degree of deformation. In this way, a continuation of the rays 57, 58, 59 is formed in the zone of their connection with the central part 60. The portion of the cross-sectional area taken up by the segregation remains invariable. After that, the beam

58 (FIGS. 52 to 53) separated from the central part 60. By pre-rolling the flank of the beam 58 perpendicular to its radius, the roller does not act over the entire length of the beam 58, but rather on the section with the metal which is free from segregation. With regard to the fact that the rough rolled product has previously been deformed by 10 to 30% and that the length of the side surface of the beams 57 »58 and 59 has increased by 2 to 50% compared to the original one by their deformation and artificial elongation the elimination of 1.02 to 1.5 times the original size of the flank of the beam 58 the possibility of achieving the required effect - the production of a billet of guaranteed quality. The process of beam separation is thereby significantly simplified due to the prevention of the influence of the beam to be displaced on the remaining elements of the ingot. During the displacement of the beam 58 and is kept in the on-center T _e il 60 abutting portion, the segregation zone is in the. As a result, the beam 58 is shifted without deforming the beams 57 and 59. In other words, a continuation of the beams 57, 58, 59 is formed from the central part of the block serve as a support due to the mutual displacement. If a raw slab is produced in the continuous caster, high-quality billet rods can be made from it as follows

produce. The starting slab 62 (FIG. 54) has a segregation zone 63 concentrated in its central part. The height of segregation zone 63 is approximately 0.3 times its width. Then the central part of the slab is opened and a complete raw block, consisting of two beams 64 and 65 (Fig. 55), in the rolls 66 of a rolling mill shaped. The opening of the central part of the starting slab 62 is carried out by preferably gate rolling the slab 62 in the segregation concentration zone 63. Thereupon: a complete Rohbloek, which consists of two rays 67 and 68 (Fig. 56), which with the central part 69 with a

the
Thickness of 0.3 to Ο, Ι'ΉοΙιβ of the starting slab 62 are connected, formed. In a caliber with two incisions of the rollers 70, the segregation is carried out on the opposite sides of the complete ingot and its concentration in the central part 69, the width of which is 0.4 to 0.7 times the height of the starting slab 62. By pre-rolling the slab 62, preferably in the region of the segregation concentration up to a thickness of 0.3 to 0.1 height of the starting slab 62, the segregation zone 63 is led out onto the surface of the central

from

Part 69 taking into account ^ its decrease in height in Rolling process guaranteed. When the segregation zone 63 is opened, there is an increase in width in addition to the expansion this zone in front of you. By shaping the central part 69 of the complete ingot with a width of 0.4 to 0.7

Above the starting slab 62, the delimitation of the segregation zone 63 in the central part 69 is ensured, taking into account the width of the segregation zone 63 in the rolling process with different aspect ratios of the starting slab 62 (within 1.05 to 2.0). After delimiting the segregation zone 63 in the central part 69 of the complete ingot, the rough rolled product is formed, which consists of two with the central part 73 in a caliber 74, where the minimum presence of the non-segregated metal in the zones 75 and 76 of the junction of the beams 71 and associated beams 71 and 72 (Fig. 57) is ensured 72 with the mitti _r gene part 73 is formed. Thereafter, the beams 71 and 72 are separated from the central part 73 in the zones 75 and 76, for example by cutting the rough rolled product with saws in the longitudinal direction.

When the process of separating the rays from the central part of the complete ingot in the longitudinal direction in the Rolling of a rolling mill runs where one of the beams is held and the beams adjacent to these are below the influence of the upsetting surface of the caliber are shifted,

hang,. "

so y * the parameters of this process and its business management Key figures especially from the. Temper at ural conditions its implementation. With the increase in temperature, the degree of mutual displacement increases Rays that must be given to them to separate them from the central part, too. As the temperature decreases, it increases strengthens the rays intensively, which leads to the wax

iiü83 / Il37 ORIGINAL INSPECTED

turn of the energy force parameters of the separation process leads. The optimum for high-alloy steels the process guide interval in the beam separation is a temperature range of 570 to 74o C. ⁰ With respect to the melting point of the metal is it from 0.37 to 0.48. The degree of displacement of the rays, which is necessary for their separation, does not exceed 65%. With this variant, it is possible to combine a continuous caster, with which the complete strand is produced, with a rolling mill, where the beams are separated from the central part of the complete strand.

In various methods of separating the beams of the complete ingot from its central part, it makes sense to make changes in the cross-section at the junctions of beams 77 and 78, 78 and 79, 79 and 77 (S ¹ Ig. 58) that lead to stress accumulations . The cross-sectional changes leading to stress accumulations can have various shapes, for example as notches 80, 81 and 82. The depth of the notches 80,81 and 82 must

the
be less than 0.07V beam height, and their maximum width and depth are limited by the conditions of the application of the cross-sectional changes leading to stress accumulations. During the subsequent separation of the beams 77, 78 and 79 in the rolls of the rolling mill, the notches 80, 81 and 82 considerably simplify the separation process.

The practice of the invention offers the possibility of secondary cavity growth (s-free billets in continuous casting

Wt $ Ö3 / Ö837

process to produce. At the same time as the quality improvement of the billets produced, the present invention has a high level of economic effectiveness. By improving the quality of the metal, selecting the optimal separation process and increasing the performance of the continuous casting plants, the cost of finished products is reduced by 17 to 21%, while the costs associated with processing the separated central part increase the cost by around 7%.

The previous lack of usable procedures to eliminate segregation during crystallization of the block suggests that the special solution described in the present invention is economically advantageous and is easy to implement. The yield of usable high-quality billets is 82 to 92%.

I83 / Ö837

eerseite

Claims (14)

PATEHTLISM: 1. Single-bar manufacturing process, which is the production complete raw blocks with star-shaped, centrally symmetrical This is a cross-section relative to the central longitudinal axis of the complete raw block, characterized in that the segregation zone (6, -55, 63) consists of the rays (2, 3, 4, 14, 15, 16, 20, 21, 22, 25 , 26, 27, 28, 39, 40, 41, 42, 50, 51, 52, 53, 57, 58, 59, 64, 65, 67, 68, 71, 72, 77, 78, 79) of the complete ingot is led out, whereby the segregation zone (6, ^ _t 63) is delimited in the central part (5, 17, 23, 24, 43, 49, 60, 69, 73) of the complete ingot (I) and then the rays (2, 3, 4, 14, 15, 16, 20, 21, 22, 25, 26, 27, 28, 39 »40, 41, 42, 50, 51, 52, 53, 57, 58, 59, 64, 65, 67, 68, 71, 72, 77, 78, 79) of the complete ingot (I) from the central part (5, 17, 23, 24, 43, 49, 60, 69, 73). 2. billet manufacturing process according to claim I, d a through characterized in that the complete ingot (I) with a star-shaped cross-section with at least two rays (2, 3, 4, 14, 15, 16, 20, 21, 22, 25, 26, 27, 28, 39, 40, 41, 42, 50, 51, 52, 53, 57, 58, 59 , 64, 65, 67, 68, 71, 72, 77, 78, 79) is generated, the one base area of each of the beams (2, 3, 4, 14, 15, 16, 20, 21, 22, 25, 26, 27, 28, 39, 40, 41, 42, 50, 52, 55, 57, 58, 59, 64, 65, 68, 71, 72, 77, 78, 79) in the connection zone with the central part (5, 17, 23, 24, 43, 49, 60, 69, 73) of the of the complete raw block (I) 0.72 to 2.3 ^ hull of the beam 109883/0037 (2, 3, 4, 14, 15, 16, 20, 21, 22, 25, 26, 27, 28, 39, 40, 41, 42, 50, 51, 52, 53, 57, 58, 59, 64 , 65, 67, 68, 71, 72, 77, 78, 79) and the other base area 0.5 to 1 ^v height of the beam (2, 3, 4, 14, 15, 16, 20, 21, 22, 25, 26, 27, 28, 39, 40 , 41, 42, 50, 51, 52, 53, 57, 58, 59, 64, 67, 68, 71, 72, 77, 78, 79). 3. billet manufacturing method according to claim 2, characterized in that a complete ingot is produced with a star-shaped cross-section, in which one of the flanks of each beam (14, 15, 16) of the complete ingot is 3 to 15 % longer than the other. 4. Billet production method according to claim I, d adurch characterized in that the rays of the complete ingot with a star-shaped cross-section be separated from the central part at the same time. 5. billet manufacturing method according to claim!, Characterized characterized in that first two beams (20, 21) from the complete Sohblock with star-shaped Cross-section with three beams (20, 21, 22) and then the central part (23) of the remaining beam (22) be separated. 6. billet manufacturing method according to claim I, d adurch characterized in that the beams (2, 3, 4) by the action of the caliber of a roller (7, 8, 9) on one of the planks of only one beam (2, 3, 4) from the central part (5) of the complete ingot after another s / be separated. 109883/0837 7 · Billet manufacturing method according to claims I and 6, -ä -ä durchgeke η η ζ calibrate η et that the W & x direction of displacement after the displacement of the beam dor (2, 3, 4) by a size of 0.57 to 0.92 ^ height of the ray (2, 3, 4) is changed into. The opposite. 8. billet manufacturing process according to claims I and 5 »dad arch marked that from the Complete raw block with a star-shaped cross-section with three rays (20, 21, 22) formed a T-profile, then from this two opposing beams (20, 21) are separated, being relative to the remaining part of the profile be moved, after which the central part (23) of the complete Ingot is separated from the remaining beam (22). 9. billet manufacturing method according to claim I, characterized in that first two opposing jets (26 and 28) by shear deformation in the rollers (29, 30, 31 »32, 33) from the complete Raw block with a star-shaped cross-section with four rays (25 »26, 27, 28) and then the two remaining ones Beams (25 and 27) separated from the central part (24) will. 10. billet manufacturing method according to claims I and 9, characterized in that a Complete ingot with a star-shaped cross-section with four rays (39, 40, 41, 42, 50, 51, 52, 53) with a ratio the axial dimensions of the mutually perpendicular rays of 109883/0837 1.05 to 1.5 produced and the rest of the block part at the same time with the separation of the two opposing beams (40, 42, 50, 51) of lesser height is, the smaller rays (40, 42, 50, 51) with a cross-sectional area that is 1.05 to 1.5 times is larger than the cross-sectional area of the parts (44, 45, 47, 48) to be produced from these beams (40, 42, 50, 51) be separated. 11. Billet manufacturing method according to claim!, Characterized characterized in that before the production of the complete ingot, a strand (54) with a Cross-section in the form of a rectangle with a side c \ "Ί ^ ^! OTT) Ratio of 1.0 to 1.8 continuously cast, from ν in the rolls a complete ingot (56) with a star-shaped cross-section the with four rays with a ray height of less than a quarter of a quarter of the ingot (54) to be cast and with a ratio of the axial dimensions of the opposing beams of 1.0 to 2.8 and then the beams are separated from the central part of the complete ingot (56). « 12. Billet manufacturing method according to claims I and 2, characterized in that each of the beams (57, 58 »59) after leading out of the segregation zone from the beams (57, 58, 59) of the complete ingot by 10 to 50% in one to the radius of the beam _{i37 9} 58, 59) is deformed in the perpendicular direction, whereby the segregation zone is deformed simultaneously with the beam (57, 58, 59) 169683/0837 χ 282832? taking place forrolling the central part (60) of the complete Eohblocks is inserted into the strand (57, 58, 59), after which the rays (57, 58, 59) with a height that 1.02 to 1.5 times the original height, separately turn around, 13 * billet production method according to claim 1, by characterized in that the complete JRohar block with a star-shaped cross-section with two rays a continuously cast slab (62) having an aspect ratio from 1.05 to 2.0 is produced, for which purpose the slab (62) is rolled down in the segregation concentration zone, wherein the segregation zone (6J) in the middle 0.3 to 0.1 ^v thickness that of the slab (62) thick and 0.4 to 0.7 ^ DiCkC of the slab (62) wide part (69, 73), and then the rays (64, 65, 67, 68, 71, 72) of the complete ingot separated from the central part (69, 73). 14. billet production method according to claims 1.5 to 13, characterized in that the Separation of the rays (2, 3, 4, 14, I5, 16, 20, 21, 22, 25, 26, 27, 28, 39, 40, 41, 42, 50, 51, 52, 53, 57, 58, 59) <3rd complete block from the central part (5, I7, 23, 24, 43, 49, tiO, 69, 73) at a temperature of the metal from 0.37 to of
0 _f 48v the melting point of the metal is made, with the rays (2, 3, 4, 14, 15, 16, 20, 21, 25, 26, 27, 28, 39, 40, 41, 42, 50, 51, 52, 53, 37, 58, 59) can be shifted by 40 to 65% relative to their starting position. 109883/0837 - i / - . 282832? 15 · Longitudinal billet manufacturing process according to. Claims 1.5 up to 13y. characterized in that a cross-section leading to stress accumulations is included, the
E.g. 0.07 Dis 0.2 ^v hones of the ray (77 t 78, 79) deep and the 0.02 to 1/8 height of the ray (77, 78, 79) wide notches (80, 81, 82) before the separation of the rays (77, 78, 79) of the complete ingot from the central part at the junction of the rays (771 78, 79). 109883/0837