SU1736673A1 - Method of continuous ingot casting vertical and curvilinear installations - Google Patents

Abstract

The invention relates to metallurgy, in particular to the casting of metals in a continuous manner. Liquid metal is supplied from the tundish to the mold through a submerged refractory tube and pulsatedly mixed in the mold by periodically filling and displacing the metal from the refractory tube. The initial hydraulic diameter of the expelled jet is determined by the proposed relationship. On curvilinear installations, the metal jet, displaced from the refractory tube, is directed toward the curvature of the ingot at an angle to the vertical, equal to 24-28 R a57. where 24-28 is an empirical coefficient. 1 hp f-ly. 4 ill., 1 tab. sl C

Description

The invention relates to metallurgy, in particular to the casting of metals in a continuous manner, and can be used in the casting of ingots on curvilinear and vertical machines.

A known method for the continuous casting of metals involves the periodic filling of the ceramic pipe additionally introduced into the mold and forcing it out into the volume of the mold by varying the pressure of the inert gas in the pipe proportional to the movement of the mold.

The disadvantage of the method is the absence of conditions for effective mixing of the metal, since it is expelled from the pipe and filled with metal at a relatively low speed determined by the frequency and pattern of movement of the mold. Along with this, the use of an additional refractory tube for the impact on the metal, which is not located along the ingot axis, increases the consumption of refractory materials on the one hand, and structural and chemical heterogeneity of uninterruptedly cast billets on the other.

Closest to the invention is a method for continuous casting of ingots, which includes feeding metal from a tundish into the mold through a refractory tube and pulsating stirring of the liquid phase of the ingot by periodically filling and displacing the metal from the refractory tube

vj with about o- vj

CJ

speed (3-4) displacement of the metal from the tundish, and the filling time is

0.0-1.1),

where d is the diameter of the jet of metal flowing from the tundish, m;

D is the diameter of the jet of metal flowing from the refractory tube, m;

Ah - fluctuation of the metal level in the crystallizer in the process of pulsation, m;

V - pouring speed, m / min.

The disadvantages of the known method of continuous casting are the formation, at the indicated rates of displacement of metal from the refractory tube, of gas-containing vortices of an annular shape, which, falling down, come into contact with the shell of the hardening ingot in the crystallizer and the secondary cooling zone. In the process, the crystallization shell is smeared with gas-containing vortices and the metal is saturated with the gas introduced by them, which leads to breaks of the ingot crust under the crystallizer, causes the formation of macrostructure defects: cracks, blotchy liquidation, chemical and physical inhomogeneity,

As laboratory studies and castings have shown, the formation of a gas vortex in the process of displacing metal from the refractory tube is due to the fact that the stream of metal flowing from the tundish, entering the pipe, injects gas from it, located in a part of the pipe immersed in it, and distributed in the metal as separate bubbles. When the pressure in the pipe is increased, the metal is displaced from it, and at the exit from the pipe the metal flow acquires a rotational-translational motion in a vertical plane, forming a ring vortex of toroidal shape, which descends into the liquid phase of the ingot. The reason for the occurrence of such a vortex is due to the formation of a boundary layer metal near it when the metal moves in it, which is torn off at the edge of the pipe, resulting in a thin metal layer with significant vorticity. Then there is a folding of this layer, which leads to the formation of a vortex.

As the metal is expelled from the pipe, the vortex moves downward with a simultaneous increase in the outer diameter and cross-section. Rotational

the movement of the metal in the vortex reduces the static pressure in it. This leads to the fact that gas bubbles, displaced together with the metal flow from the refractory tube, are drawn into the vortex, forming a closed toroidal gas ring around its center of rotation,

By the time the direction of movement of the liquid metal in the pipe changes, the rotational-translational movement acquires almost the entire flow of metal displaced from it. At the same time, at the exit from the pipe, the speed of the translational motion of the vortex is equal to the speed of displacement of the metal. As the ingot is lowered in the liquid phase, the speed of movement of the gas vortex decreases. Upon reaching a certain depth, the gas ring under the action of buoyancy forces and the viscosity of the metal breaks down into separate bubbles that float in the liquid phase of the ingot onto the surface of the metal in the crystallizer. In this case, the mixing of the molten metal in the ingot occurs not only due to the annular gas-containing vortices moving downwards, but also by the bubbles of gas emerging after their destruction.

However, the destruction of the vortex occurs as a result of contact with the solid shell of the ingot, primarily with the crystals growing towards its center, which leads to their breaking. In this case, the speed of the vortex decreases, but it still continues to move down. The complete destruction of the vortex occurs after its contact with the hard shell of the ingot. If the center of the vortex coincides with the axis of a continuously cast ingot, then the contact of the vortex with the shell occurs at a depth where the outer dimension of the vortex is equal to the transverse size of the liquid well of the ingot.

When the vortex moves away from the ingot axis, the vortex collides with the shell at a smaller depth, i.e., when the size of the vortex is smaller than the transverse size of the well.

Thus, the maximum distance in the liquid phase of the ingot passes the vortex if it does not come into contact with its shell, and the minimum distance does not coincide with the center of the vortex with the axis of the ingot. With a decrease in the transverse size of the vortex, all other things being equal, the depth of its penetration into the liquid phase of the ingot increases.

Upon contact of the annular gas-containing vortex with the shell of the ingot within the mold, where the shell of the ingot is thin and has low strength, it is eroded, causing the formation of cracks and breakthroughs of the metal.

For example, when casting steel ShKh15 on machines of the vertical type in accordance with the parameters given in the exemplary embodiment of the prototype: ingot cross section 265x340 mm, inner diameter of the cup in the tundish 25 mm, casting speed 0,0108 m / s, inner diameter of the refractory pipe 100 mm, the depth of its immersion in the metal is 0.6 m, the rate of outflow of the jet from the tundish glass is 2.0 m / s.

Under these conditions, it has been found that the vortex strikes the ingot envelope at a distance of 0.77 m from the metal meniscus in the mold.

If the annular gas-containing vortex is in contact with the ingot shell in the secondary cooling zone, then a part of gas bubbles floating up in the metal after the vortex is immersed is entangled between the growing crystals of the dendritic form. During the solidification of the ingot, these bubbles diffuse and accumulate there the harmful gases contained in the metal, nonmetallic inclusions, liquidating elements, which cause the appearance of such defects of the macrostructure of the ingot as spotty segregation, point heterogeneity, etc. These conditions are created if, in accordance with example given in the prototype, get ingots section 335x400 mm, pouring them through a glass inner diameter of 31 mm. It was established that in such a case the gas vortex is in contact with the ingot shell at a distance of 2.09 m from the metal meniscus in the crystallizer, i.e. in the secondary cooling zone. The final destruction of the vortex occurs at a distance of 3.2 m from this level. This reduces the thickness of the zone of columnar crystals due to a corresponding increase in the size of the zone of equiaxed crystals. However, part of the gas remains in the ingot, which leads to the indicated defects of the macrostructure.

Using a prototype for casting on curved machines is practically impossible, since it does not provide a positive result.

In such conditions, the trajectory of the gas-containing vortex, moving with a straight line, does not coincide with the longitudinal axis of the ingot, curved under a certain radius. As a result, there is an undermining of the solidifying shell of the ingot along a large radius. If, using various techniques, even to ensure the coincidence of the axes of the ingot and the vortex in order to eliminate this drawback, the issue of the removal of gas from the ingot by the vortex remains unresolved. On curvilinear machines, due to the curvature of the solidifying ingot, the likelihood of a delay of vertically emerging gas bubbles formed after the destruction of a vortex is much higher than in ingots molded on vertical machines, which causes the appearance of defects in the macrostructure.

Thus, it is practically impossible to significantly reduce the chemical and physical inhomogeneity of the ingot only by pulsation mixing of the metal.

The purpose of the invention is to improve the quality of continuously cast ingot by reducing its chemical and physical heterogeneity.

This goal is achieved due to the fact that according to the method of continuous casting of ingots, which includes feeding metal from the tundish into the mold through a refractory tube and pulsating stirring of the liquid phase of the ingot by periodically filling and displacing the metal from the refractory tube with gas, the following methods are provided.

The metal is displaced from the refractory tube to form a jet with an initial hydraulic diameter.

2, 5a + 0,0115h- 2J -0.016

J

The displacement of metal from the refractory tube is carried out at a rate (o) ensuring the formation of annular gas-containing vortices in the liquid phase of the ingot, and when lowering the ingot in the liquid phase, the annular gas-containing vortices do not contact the shell of the ingot. In this case, annular gas-containing vortices penetrate into the liquid phase of the ingot to a depth that prevents the gas introduced by them from delaying in the ingot.

When casting metal on vertical machines, the rate of metal displacement from a pipe is chosen within

f 0.6

-pi to

Li-h

0.6

When casting metal on curvilinear machines, the metal jet displaced from the refractory tube is directed toward the curvature of the ingot at an angle to the vertical a (24-28), and the speed of displacing the metal from the refractory tube depending on the ratio of the distances along the ingot axis from the meniscus. metal in the mold to

contact point of gas-containing vortex with the shell of the ingot

./ 2k / 2io2,

4 No. r0 092 (2D-a 0 023h)

0.046

and to the point of penetration of the gas-containing vortex into the liquid phase, above which it is not possible to remove their ingot by the gas introduced by the vortex, 017R (90-80) is determined from the expressions:

16 s / p - h

D

ri -2; 16s / p -h

D

0.6

sh

L-2-h 5

1G

F

0.6

sh

H)

D

0.6

with L2,

where d is the hydraulic diameter of the metal stream flowing from the tundish, m;

a is the thickness of a continuously cast ingot, m;

h is the depth of immersion of the refractory pipe in the metal, m;

K - metal solidification coefficient, m / min;

V - metal casting speed, m / min;

R is the base radius of the curvilinear machine, m;

f, F is the cross-sectional area of the metal jet, respectively, flowing out of the tundish and displaced from the refractory tube, m2;

s is the cross-sectional area of the ingot, m;

P is the perimeter of the ingot cross section, m.

FIG. Figure 1 shows the flow pattern of the gas vortex in the liquid phase of the ingot; in fig. 2 is a diagram of the emergence of gas bubbles in the liquid phase of the ingot, resulting from the destruction of the gas-containing vortex; in fig. 3 is a diagram of the penetration of a gas-containing vortex into the liquid phase of the ingot with on FIG. 4 too. at.

The essence of the proposed method for continuous casting of ingots is as follows.

In the mold 1 (Fig. 1) with a liquid metal 2, a refractory tube 3 is immersed, hermetically connected to the tundish 4. The metal is expelled from the refractory tube by increasing

the pressure in it is due to the supply of gas through the nozzle 5. The filling of the refractory pipe with metal occurs as a result of a decrease in the pressure in it when it is connected to the internal cavity with the atmosphere or with a suction device.

The hydraulic diameter of the jet of metal displaced from the refractory tube is.

ten

2.2d, 5a + 0.0115h1, 183 K

-0,016.

15

20

25

thirty

35

The displacement of the metal from the refractory tube is carried out at a rate that ensures the formation of annular gas-containing vortices in the liquid phase of the ingot 6. During each period of the displacement of metal from the pipe, one vortex is formed. The gas enters the vortex from the refractory tube 3 due to the injection of its metal jets coming from the tundish 4.

The gas-containing vortices 6, when lowering the ingot in the liquid phase, do not come into contact with its shell 7, which prevents its erosion. Having reached a certain depth, gas-containing vortices under the action of buoyancy forces and metal viscosity are destroyed with the formation of gas bubbles 1 (Fig. 2) that float to the surface of the metal in the crystallizer. In this case, the gas introduced by the vortex is completely removed from the ingot.

When casting metal on vertical-type machines, the metal jet stream displaced from the refractory tube coincides with the longitudinal axis of the ingot, i.e. angle a 0, and the rate of displacement of metal from this pipe is chosen within

40

f} 0 6

-pi w

Li-h

0.6

five

0

five

3-0.57

When ingots are produced on curvilinear machines, a jet of metal displaced from the refractory tube is directed toward the curvature of the ingot at an angle to the vertical.

a (24-28) K

In such conditions, the trajectory of the gas-containing vortex coincides with the longitudinal axis of the ingot, curved under a certain radius, which eliminates the contacting of the vortex with the ingot shell.

On curvilinear-type machines, the rate of displacement of metal from the refractory tube, depending on the ratio of the distances along the axis of the ingot from the metal meniscus in the mold to the point of contact

gas gas rye alkali vortex with ingot sheath (Fig. 3, 4)

IM / 2k

4 + No. r0l092 (2D 0 0 | 023hl

0.046

and up to the point of penetration of the gas-containing vortex into the liquid phase, when exceeded, which does not ensure the removal of the ingot introduced by the gas vortex,

, 017R (90-80Va05) is determined from the expressions:

, 0.6,. ,, 6

16s / p-h / 1

D with Li L.2;

16s / p-h (1

tm (o

L2-h

V5

0.6

sh

C - h / f

VrJ IF

0.6

at.

It has been established that if the hydraulic diameter of the metal jet displaced from the refractory tube,

D 0.5a + 0.0115h- - 0.016,

A7

then the gas-containing vortices that arise are in contact with the shell of the ingot within the mold, and this is accompanied by its erosion and may lead to a breakthrough of the metal below the mold.

When the hydraulic diameter of the metal jet

2d

the gas content of the metal in the refractory pipe increases dramatically, which is associated with a similar increase in the injecting effect of the metal jet, which increases with a decrease in the ratio of cross sections of the metal jets flowing out of the tundish and displaced from the refractory pipe. Under such conditions, the metal loses continuity, as a result of which the space between the inner walls of the refractory tube and the metal stream emanating from the tundish is filled with foam, when displaced into the liquid phase of the ingot, no vortices form.

In the proposed range, the change in the hydraulic diameter of the metal jet displaced from the refractory tube, its reduction, all other things being equal, causes an increase in the gas content of the metal in the tube without loss of continuity. However, the mass of metal displaced from the refractory tube is reduced, and the volume

0

five

the gas in the vortex increases, which requires an increase in the rate of displacement of the metal from the pipe to obtain gas-containing vortices reaching a predetermined depth in the liquid phase of the ingot.

The optimum limit on the hydraulic diameter of the metal jet displaced from the refractory tube is reached when the specified diameter is above its lower claimed limit by 20-60% of the difference between the upper and lower limits, i.e.

, 2d + (0.5a + 0.0115h- 1 183K 20-60

-0,016-2,2d)

100

20

25

thirty

35

40

At lower values of the hydraulic diameter of the metal jet at the exit of the refractory pipe, the quality of the unbroken ingot does not noticeably improve, but at the same time the costs of implementing the invention increase substantially due to the need to ensure high speeds of metal displacement from the pipe. Exceeding the optimum value of the hydraulic diameter of the metal jet is accompanied by a decrease in the distance from the metal meniscus in the mold to the point of contact between the gas-containing vortex and the ingot shell, i.e. a decrease in the depth of its penetration into the liquid phase of the ingot, and this causes an increase in the length of the zone of columnar crystals and an increased segregation in the ingot.

It has been established that, for the conditions of metal casting on vertical machines, the rate of displacement of metal from the refractory tube, which ensures the occurrence of annular gas-containing vortices that mix the liquid phase of the ingot in the secondary cooling zone without saturating the metal with gas,

16s / p-h / h iF

v

D

0.6 ± 0)

C-h

0.6

When displacing the metal from the refractory tube at a speed lower than the proposed path of movement of the annular gas-containing vortex does not exceed the depth of propagation of the metal jet during ordinary casting, which does not achieve its goal. The displacement of the metal from the refractory tube at a speed higher than that claimed is accompanied by the ingot being saturated with gas introduced by the vortex, because in this case the vortex movement path, taking into account the depth of the refractory tube into the metal in the mold, exceeds the distance from the metal meniscus to the point of gas-containing contact whirl with ingot shell.

The most intensive mixing of the solidifying metal in the secondary cooling zone and its stable quality are ensured at the optimum rate of metal displacement, which is less than the upper claimed limit by 5–15% of the difference between its upper and lower limits, i.e.

Li-hm ° -6 Ki-n / n0-6 VD iF

0.6

5-15,100

The displacement of the metal from the refractory tube at a speed below the optimum, although it provides for the averaging of the composition of the metal during its crystallization, but does not allow for a significant reduction in the length of the zone of columnar crystals, as is the case at optimum speeds. The displacement of the metal from the refractory tube at a speed higher than optimal is characterized by the instability of the quality of the metal due to the not always complete displacement of the gas from the ingot by the vortex.

When casting on curvilinear machines, the displacement of a stream of metal from the refractory pipe in the direction of the ingot bending at an angle to the vertical

a (24-28)

provides the maximum path of movement of the vortex in the liquid phase of the ingot and eliminates the one-sided washing away of its hard shell. When the jet axis is tilted to the vertical at an angle below the claimed annular vortices break up into the ingot shell of a larger radius, and above a smaller radius, in one case causing one-sided erosion. In addition, in both cases, the path of movement of the ring vortex is significantly shortened, which reduces the intensity of mixing.

The optimum angle of inclination of the jet axis to the vertical is determined by obtaining the highest quality metal, which is achieved with

a (25-27) I am 0 57,

ensuring the coincidence of the axis of motion of the vortex with the longitudinal axis of the ingot. This allows the vortex to go the longest way and, accordingly, to maximize its energy for mixing the liquid phase of the curved ingot. However, it is unlimited to increase the vortex movement path in these ingots, as in

vertical, it is not possible, since the gas introduced by the vortex may, starting with some kind of limiting distance from the metal meniscus to the point of the vortex penetration into the liquid phase

ingot, remain in it, causing defects in its macrostructure. It is established that the maximum distance from the metal meniscus in the mold to the point of penetration of the gas-containing vortex into the liquid phase

an ingot, in which the gas introduced by the vortex is not removed from it (Fig. 3, 4), is

, 017R (90-80 ° ° 05). At this or a greater distance, the gas contained in the vortex, floating upwards in the form of bubbles, comes into contact with the shell of the ingot of a smaller radius and, therefore, with dendritic crystals, whose axes are located due to the curvature of the ingot.

in relation to the vertical, not under a blunt one, as in vertical ingots, but under a straight or even acute angle, which causes the ingress of bubbles into intercrystalline regions, from where they are not able to

spontaneously float to the surface of the metal in the mold.

Depending on the radius of the curvilinear machine, the parameters of the ingot and the casting conditions L.2 may be less than U (Fig. 3),

equal to or greater than it (Fig. 4). In any case, if the path of movement of the vortex in the liquid phase of the ingot in sum with the immersion depth of the refractory tube exceeds Li for Li or I.2 for (Fig. 3), then

gas bubbles remain in the ingot, which causes a decrease in its quality.

An important technological parameter determining the path of the annular vortex in the liquid phase of the ingot is the speed of displacement of the metal from the refractory tube, which for casting conditions on curvilinear machines is selected depending on the ratio and LL If (Fig. 3), then the restriction in the path of motion

the vortex is and the rate of extrusion is found by the following empirical expression:

16s / p-h (i

Tgg

06

(

L2-h

0.6

five

and if (fig. 4), then the limitation on the path of the vortex is the distance LL. In this case, the speed of displacement of the metal from the refractory tube is determined from the inequality

, 0.6, u .6

L / p-h (lY (

V

D

D

which is also used for casting conditions on vertical machines.

When displacing metal from a refractory tube at a rate of

16s / p-h ffN ° 6

Vd f

. below the lower claimed limit, the path of the vortex does not exceed the depth of the metal stream in the ingot flowing from the tundish, which does not ensure the mixing of the metal in the secondary cooling zone.

Displacement of metal from the refractory tube with speed

ABOUT)

U-h

Vd

0.6

at which annular gas-containing vortices penetrate a distance equal to or greater than La, from which gas bubbles after vortex destruction cannot completely float to the metal surface in the crystallizer, leads to saturation of the ingot with gas, mostly in the area adjacent to the shell of a smaller radius.

The optimum rate of displacement of the metal from the refractory tube with Li below the upper claimed limit is 5-15% of the difference between the upper and lower limits, i.e.

(i

0.6

L2-h / T

Vd

0.6

0.6

5-15,100

At these values of the rate of displacement of the metal from the refractory tube, the highest and stable quality of continuously cast steel is ensured. The displacement of the metal from the refractory tube at lower than optimal rates is accompanied by a deterioration in the quality of the metal due to insufficient mixing of the liquid phase of the ingot during its crystallization. Under the conditions of exceeding the optimal values of the speeds, the instability of the quality of the metal increases due to the gas that is not always completely released from the ingot by the vortex.

The reason for saturation of curvilinear ingots introduced by a vortex with gas is identical to that considered for the conditions for casting vertical ingots. Therefore, the justification of the claimed limits and the optimal rate of displacement of the metal from the refractory tube for curvilinear

ingots in this case coincide with those described for vertical ingots.

Examples The proposed method is illustrated by the following 2 examples of its implementation, of which Examples 1-9 relate to a vertical caster, and Examples 10-22 are of a curvilinear type, Example 23 refers to the prototype method. On vertical and curvilinear type continuous casting machines, continuously cast billets are cast with a cross section of 265x340 and 335x400 mm, respectively, from steel 20 of the following chemical composition,%: C 0.19; Mp 0.55; Si 0.3; S 0.035; P 0.035; Ni 0.25; Si

5 0.25; Cr 0.25; AI 0.02. In all examples, the temperature of the steel in the tundish is in the range of 1530-1550 ° C, the height of the metal in it is 0.67 m, the speed of pouring and discharge of the metal stream from the intermediate ladle is 0,0108 and 2.0 m / s, respectively immersing the refractory tube intended for pulsating mixing and protecting the metal jet from the secondary oxidation in the area of the intermediate ladle-mold, is 0.6 m or 0.9 of the height of the metal in the tundish. All refractory tubes have a cylindrical shape with a wall thickness of 30 mm. Isolation of the metal surface in the crystallizer from the oxidizing atmosphere is ensured by the introduction of slag in it consisting of 15% cryolite, 8% boric anhydride, and 77% graphite.

5 The displacement of the metal from the refractory tube is carried out with argon. The supply of the latter to the refractory pipe and the removal of exhaust gases from it are carried out using a piping system and shut-off

0 fittings consisting of metal pipes with an internal diameter of 15 mm, control valves, inlet and exhaust valves connecting the cavity of the refractory pipe in its upper part, respectively, but with the argon pipeline and atmosphere. The argon pressure in the line is 0.6 MPa, and the change in its limits in the cavity of the refractory tube is from atmospheric to 135-137.3 kPa, which is

Depending on the outer diameter of the pipe and the cross section of the mold, the metal level in it is lowered by 0.5 m. The displacement rate is controlled by changing the argon inlet time, i.e. him

5 flow, with the help of control valves.

The perimeter of the ingot produced by the vertical machine is 1.21, and on the curvilinear - 1.47 m. The base radius of the curvilinear machine is m. The hydraulic diameter of the metal stream flowing from the tundish during metal casting on a vertical and curvilinear caster is respectively 0.025 and 0.031 m. The same values correspond to the diameters of the pouring cup of tundishes.

Example (all parameters claimed are optimal values. The solidification coefficient of the metal in this and other examples is assumed to be 0.028

m / min0 5).

The hydraulic diameter of the jet of metal displaced from the refractory tube, exceeding the lower claimed limit by 40% of the difference between the upper and lower limits, is

D 2.2 0.025 + (0.5 0.265 + 0.0115x 1.183 0.028

HO, 60, 0108 60 40

-0.016-2.2x

x 0.025), 066 m.

Since the hydraulic diameter of the cylindrical refractory tube (D) is equal to its inner geometrical diameter (DB), i.e.

D

4 p Rv 2/4 KDB

 DE

Then, the specified hydraulic diameter of the metal jet is achieved using a refractory tube with an inner diameter of DB of 0.066 m. The outer diameter of the refractory tube (DH) with a wall thickness of 30 mm is + 2 0,, 066 + 2 0, 126 m. When the metal is displaced from this refractory tube, an annular gas-containing vortex appears, moving into the deep layers of the liquid phase of the ingot. The distance from the axis of the ingot from the meniscus of the metal in the mold to the point of contact between the vortex and the hard shell of the ingot is

2-0.02V

, +

Lr

vlO.CH08.60 SHOSHV-60,

/ 2-0,028 g. /

(ol J-Q092 (2-Q066-a265-0-023 0-6)

0.046

The optimum rate of displacement of the metal from the refractory tube below the upper claimed limit of 10% of the difference between the upper and lower limits is

2.05-0.6 / 0. G2.05-0.6g 1o.06b (0,0bbg / .066 /O.Q252 ° -6 (6-0.34-0.265 / 4.21-0.630

0.066

/ 0,025 Y 6 0. 66m / s

U.0662 / J 100

Such a rate of displacement of the metal from the refractory tube is achieved with the duration of the inlet of argon into it

with a flow rate that during this time provides an increase in pressure in the pipe from atmospheric to 45–9.81 05 (1 +

C2 0 .028 / g 0.028 2,

o o fed0, 046

-2.05m

five

0

3.14 -0.0662 / 4

five

five

+ 1

105

0.265 0.34-3.14 -0.1262 / 4 135.8 KPa, where 7000 is the density of the liquid steel, kg / m3;

9 81 - acceleration of body strength, m / s2;

1 -10 - atmospheric pressure, Pa. EXAMPLE 2. The hydraulic diameter of the metal jet displaced from the refractory tube is lower than claimed and constitutes 1.8 hydraulic diameters of the metal jet flowing from the tundish, i.e.

, 3d 1.8 0,, 045 m

The internal diameter of the cylindrical refractory tube (DB) is equal to the hydraulic diameter of the metal jet displaced from it.

, 045 m

The outer diameter of the refractory tube 2 0, 045 + 2 0, 105 m.

The distance along the ingot axis from the metal meniscus in the mold to the point of contact of the annular gas-containing vortex that occurs in this case with the ingot envelope is

2.98 m.

The rate of metal displacement is optimal, i.e.

2.9fc-0.6 / 0,, 6 2.98-0.6

.045 0,, 045 /0..6 16.Q34--0.265M.21-Ot6.

0.025 2 ° .6 0.045e |

40 100

 5.1gm / s.

The argon inlet time of the pipe is 10

OS

g, 098m, oh, 12

and the pressure in it at the end of the displacement period

 -9.81 -0.5 (1 +

+

3.14 0.0452 / 4

0.04-6

The rate of displacement of the metal from the refractory tube, the corresponding optimum, is

E.53-0.6 | 0, o, 6 153-0.6

oz, yy i. . ;

I6.0,5t- 0,265 / 1, l2i-0.6f0, .6 (О

- - -. L h I | I -

2.97m | s. 25

boo

-10, .0562 / j 100

Argon inlet time to the refractory tube - 0.5

, 5 0.265 S, 0115 x 1.183 0.028

HO, 60, 0108 60

-0.016 0.082m.

t

0.17s.

The internal diameter of the refractory tube is equal to

W 30,082 m

The argon pressure in it at the end of the period is external

displacement of DH DB + 2-0,, 082 -2 0, 142 m.

  9.81 0.5 (1 + Distance along the ingot axis from the meniscus

314-0 0552 / 4metal in the mold to the confluence point +: - + 1 10 35 ticking of the annular gas-containing

0.265 -0.34-3.14 -0.11 / 4 wihr with ingot casing is 135.3 kPa.

2, 0.028

1- 0.028

, + l11

40,0108-60 N40,0108-60

one

0.046

The rate of displacement of metal from the refractory tube

M1-0.6 / 0.025 g 0.6 1.4-1-0, l / 0.0252

4o, oaa o.osi2, ov2 oooag1

6 O.M-0,2Ј5 /), OO, b / 0, oy5 g ofi

l1o, ovg o.ochg

0.6

 1 ° L °

0.66 m / s.

This rate of displacement of the metal is provided during the intake of argon into the pipe

0

five

135.0 kPa.

EXAMPLE 3: Corresponds to the conditions of casting, in which the rate of displacement of metal from a refractory pipe is optimal. The hydraulic diameter of the jet of metal displaced from this pipe is equal to the lower claimed limit, i.e.

D 2.2d 2.2 0.025 0.055 m.

Internal diameter of refractory tube

, 055 m, and the outer + 2 0,, 055 + 2 0,, 115m.

The distance along the ingot axis from the metal meniscus in the mold to the point of contact of the annular gas-containing

 2.53 m

EXAMPLE 4 The rate of displacement of metal from a refractory pipe corresponds to the optimum, and the hydraulic diameter of the metal stream displaced from the pipe corresponds to the upper stated limit, i.e.

 0.265 S, 0115 x 1.183 0.028

0, 0108 60

-0.016 0.082m.

-0.092 (2-0.082-0.265-0.023- 0, b)

To “LL.

Т ш ° -76с-Argon pressure in the pipe at the end of the period of displacement of metal from it is 9.81 -0.5 (1 +

3.14 0.0822 / 4

+1

105

0.265 0.34-3.14 -0.1422 / 4 136.8 kPa,

PRI me R 5. The rate of displacement of metal from the refractory tube is optimal. The hydraulic diameter of the metal jet exceeds the claimed limit and is D 0.09 m. This value corresponds to the internal diameter of the refractory tube.

DB, 09 m.

/ Ј.0.028

2.0,028 2

L, | l | o0108 b6 + 1l10 .0108-60

I

0.04

The rate of displacement of metal from the refractory tube

W-0.6 / 0,025 .6

AfaW (o, o902 |

0.025g | 0.6 1b.O.E4-0.ab5 / 4.21-0. &

O.OQO2- / 0.040

 0, .6

{Q W 0.36m / s.

0.0902 /

The duration of the argon inlet into the refractory tube

t- 0.5 1 × 8, 36 J

The nitrogen pressure in it at the end of the displacement period is 9.81-0.5 (1 +

3.14 0.092 / 4

+

) +1

105

0.265 0.34-3.14 0.152 / 4

 137.3 kPa.

EXAMPLE 6 The rate of displacement of metal from a refractory tube is lower than claimed and is 0.62 m / s. The displacement time of the metal from the refractory tube, i.e. Argon tube admission time

g $ 1 0.8, p.

The hydraulic diameter of the metal jet displaced from the pipe is 0.066 m, i.e. answers the best. All other parameters of the method required for its reproduction are as described in Example 1.

Example. The rate of displacement of the metal from the refractory tube corresponds to the lower stated limit

I) IJ..T4- II.IKJ / .Л - U.U U.

0)

V,

0.066

V0,6

0.066

 0.72 m / s.

The argon inlet time to the refractory tube is

g (S SShsOther parameters of the method correspond to those considered in example 1.

PRI me R 8. The rate of displacement of metal from the refractory pipe from

The outer diameter of the refractory tube is + 2 0,, 09 + 2 0,, 150 m. The distance along the axis of the ingot from the metal meniscus in the mold to the point of contact between the annular gas-containing vortex and the shell of the ingot

- Q, 09Јfo. 0.090-0.265-0.023-0.6

-60

0.046

Mm

the upper stated limit is 2.05-0.0 (o, 0252G 176m / s

sh

n), obb obb2

The duration of the argon inlet into the refractory tube

g 0,28s.

The remaining parameters of this example are the same as in example 1.

EXAMPLE 9 The rate of displacement of metal from a refractory pipe is higher than the claimed and equal to 1.90 m / s. The argon admission time into the pipe is

Г т1г0 26с. The remaining parameters correspond to those given in example 1.

I'll try it on. In this example, metal casting on a curved caster, all the proposed method parameters correspond to their optimum values. The hydraulic diameter of the metal jet displaced from the refractory pipe exceeds the lower claimed limit by 40% of the difference between the upper and lower limits, t. e.

D 2.2 0.031+ (0.5 0.335+ 0.0115 0.6 1, 183 0.028

0,0108 60

-0,016-2,2 0,088 m

d

45

The inner diameter of the refractory tube, since it is cylindrical, corresponds to the hydraulic diameter of the metal jet displaced from it, 088 m

The outer diameter of the refractory tube DH DB + 2 0,, 088 + 2 0,, 148 m.

The argon pressure in the pipe at the end of the displacement period is

  9.81 0.5 (1 + +3.14 0.0882 / 4

0.335 0.4 -3.14 0.1482 / 4 x 10 136.1 KPa.

-) + 1 x

The angle of inclination of the jet axis and the corresponding distance 55 along the ingot axis from the meniscus

but a refractory pipe to the vertical of the metal to the point of contact of the gas line 26 5.78 ° or 5 ° 47. holding the vortex with the ingot shell

2-0,028 / 2.0,028 2

4o.o8-bo NUobio3-60

 -0.092. (2, -0.088 -0.5-0.023 -O.b) (

0.046

The distance from the meniscus of the metal in the crystallizer to the point of penetration of the gas-containing vortex into the liquid phase, above which the gas cannot be removed from the ingot, is

12 0,017 14/90-80 (0,0108 60U ° 05

 1.96m

This distance remains constant for other examples of metal casting on a curved caster, since it depends only on the basic radius of the machine and the casting speed, which are the same for all experiments.

Since, the rate of displacement of metal from the refractory tube is determined from the expression

0.6

il sh

L2-h

D

Pub f

The optimal value of the metal displacement rate, which is lower than the upper claimed limit by 10% of the difference between its upper and lower limits, is

ABOUT

|,% - oh, b / o. "p.db-o.b / o.oz1 o

ad8PO.O & vg1 Shi1 0.088 ° - 160.5E5-0.4M.4t-0.6 | d.O

WA.Web

., J (00

(, 26M (s.

H - 0.028

L, 40, (M08-60

:, +

: 2 0,028 2-a092 (2.0,057-0, I5-a, 02E.O.b

0.046

Since, the rate of displacement of the metal from the refractory tube is chosen by Time of displacement or the duration of

 0.5

from the expression 16s / P-h / f

Vd f

0.6

 I

The optimum displacement rate of the metal, which is below the upper claimed limit of 10% of the difference between its upper and lower limits, is

.1 oer1i% .as / 0,

(.0572)

(6.0, I6 0.4 / 1.47-0, b (0, OE1g

1L6-0. & / 0, ОЯ1 °. «Г

(T

l | 0.057

0.05T

0.6 0

- -v.64 ", p.

 2.62m

Argon inlet time to the refractory tube

t 0.5 1.26

0.40 s.

0

five

0

five

PRI me R 11. The hydraulic diameter of the metal jet displaced from the refractory tube is lower than claimed and is 0.057 m. The speed of displacement of the metal from this tube and the angle of inclination of the jet axis to the vertical correspond to the optimum. The internal diameter of the refractory tube, since it is cylindrical, is equal to the hydraulic diameter of the jet of metal displaced from it, i.e.

, 057 m.

The outer diameter of the refractory tube + 2-0, 057 + 2 0, .117 m.

Argon pressure in the pipe at the end of the displacement period

  9.81 0.5 (1 + -ЗЛ Щ. х

0.335 0.4-3.14 0.1172 / 4

x, 0 kpa.

The angle of inclination of the axis of the metal jet to the vertical, as in Example 10, is 5 ° 47.

The distance along the ingot axis from the metal meniscus to the point of contact of the gas-containing vortex with the ingot shell is equal to

 4,0m

Time of displacement of metal from the pipe or the duration of the inlet of argon into it

0

g

 0.5

 0.19c.

five

0

2.64

EXAMPLE 12 The rate of displacement of metal from a refractory pipe and the angle of inclination of the axis of the metal jet displaced from it to the vertical correspond to the optimum, and the hydraulic diameter of this jet at the exit of the refractory pipe corresponds to the lower claimed limit, i.e.

, 2 0., 068 m. The same value corresponds to the inner diameter of the refractory pipe

, 068 m. Outer diameter of this pipe

 + 2 0,, 068 + 2 0,, 128 m

Argon pressure in the pipe at the end of the displacement period

  9.81- 0.5 (1 +

3.14 0.0682 / 4

Since Li is greater, the rate of displacement of the metal from the refractory tube is chosen from the expression

i6s / p-hm0-6 QJ L j.f-0-6

-lD (

The optimum rate of displacement of the metal from the refractory tube below the upper claimed limit of 10% of the difference between the upper and lower limits is

196-0,6

CJ 0, 031

0.0682

0.6 G 1.96-0.6

0, .6 16.0, 0.4 / 1.47-0.6

- hhbm / s. 100

0,, 068

(0.068) Argon intake time in refractory pipeT-J- 026c, 96

EXAMPLE 13 The rate of displacement of a metal from a refractory pipe and the angle of inclination. Since U L2, the rate of displacement of metal from a refractory pipe is determined from the following expression

168 / p-h 06

 m

The optimum rate of displacement of the metal from the refractory tube is

141-0.6 / 0, ODlV-b | 4 H-0.6 / 0.031 V 6

, 47 0, W (l10.Ts7 0, H7

6- 0.335-0.4 / U7-0.6 / 0.031 Yu ibTTfTI 0.11 H

The argon inlet time in the tube of the CRC 1.04s.

FDVm / s

x, 4 kpa.

The angle of inclination of the jet axis to the vertical, as in Example 10, is 5 ° 47.

The distance along the ingot axis from the metal meniscus to the point of contact between the gas

on the axis of the metal jet to the vertical displaced from it correspond to the optimum, and the hydraulic diameter of this jet at the exit of the pipe corresponds to the upper claimed limit, i.e.

, 5 0.335-0.0115 0.6-JS.

The internal diameter of the refractory tube corresponds to its hydraulic diameter, i.e.

DB D 0,117m. Outer pipe diameter + 2-0, .117 -2 0.03-0.177 m. Argon pressure in the pipe at the end of the displacement period i

  9.81 0.5 (1 3.14 0,1172 / 4

0.335 0.4-3.14 0.1772 / 4

x .7 kpa.

The angle of inclination of the jet axis to the vertical, as in Example 10, is 5F47.

The distance along the ingot axis from the metal meniscus to the point of contact between the gas-containing vortex and the ingot shell

EXAMPLE 14 The rate of displacement of a metal from a refractory tube and the angle of inclination of the axis of the metal being displaced from it to a 35 vertical line are optimal. The hydraulic diameter of this jet at the exit of the refractory tube exceeds the upper claimed limit and is D 0.130 m.

40 The inner diameter of the refractory tube corresponds to its hydraulic diameter, i.e.

About (), 130m. The outer diameter of the pipe is 45 DH DB + 2 0.03 - 0.130 m 2-0.03-0.190 m.

Argon pressure in the pipe at the end of the displacement period

  9.81 05 (1 f

- 25173667326

314-0 1302 / 4УГАЛ slope ° jet stream to the vertical, as

) + 1 hiv example 10, is 5 ° 47. Distance 0, 35 0.4 3.14 0.190 / 4e along the axis of the ingot from the metal meniscus to

5 points of gas contact

x 10 138.4 KPa.5. whirlwind with ingot shell

| / H. 0,028

H} .09Ј (2-0, "0-0.445-0.023-0.b) |

P 0,0108-60

0.046

Since U L2, then the rate of extrusion is Qfi-nfi / Yimi:

«« A-ronna r / io nri-immnnuni / i-rnufiui ПППРПРЛа - /, i - I t3O U, U vJ.UOl

no metal from the refractory pipe is defined)

are from the expression H), 088 0.088

i6s / p-h m ° 6ts-wM

0.6

1.31 m / s.

-, -p w -g10 Metal displacement time and, correspondingly D V / D V / argon inlet into the refractory tube

constitutes

Optimal displacement rate of QC

tal of refractory tube was 1, - 0.38s.

15 PRI me R 18. Speed displacement

(° Ј111 0 6 G5 1 | 6-metal refractory pipe exceeds

 -Jo.tio о.оо1 | L -4o. Actual, the upper claimed limit is

16.ed5-о.4й.47-о..о31а ° -61 (о1 5 m / s. Argon inlet duration

U.U51 ilU., ....

7, - "0.2m (е.n rnufiv

lipoi O.IO JtOOBTpyby

20t, 33c.

The time of argon inlet into the pipe

T - -FTn 2,5 reproduction of the claimed method, from, is described in Example 10.

Example 15: Displacement rate. Example 16. The angle of inclination of the metal stream from the refractory tube is lower than that of the vessel crowded from the refractory tube to.

0.78 m / s vertically below the claimed limit of

The argon inlet time to the tube is

 Oi64c

All other parameters, allowing users to reproduce the claimed method, correspond to those specified in Example 10. The remaining parameters of the method correspond to Example 16. The displacement rate shown in Example 10.

metal from a refractory pipe corresponds to 2Q angle J metal

the lower claimed limit of the ela VB | ityesnam with a refractory pipe, to

Verticals corresponds to the lower claimed

16 0.335 0.4 / 1.47 - 0.6 fo.0312 | limit, i.e.

W W 00882 a 24 14 533 OR 5 ° 2 °

 n Q0, i.iou, All other parameters of the method, respectively, S5 M / S - l

It is specified in Example 10.

The duration of the argon inlet in tru-PRI me R 21. The angle of inclination of the metal jet to the vertical corresponds to the upper claimed limit

0545a 28 14 ° 57 6.22 or 6 ° 13.

c - tgEe 0.6 s. The remaining parameters are the same as in

The remaining parameters of the method are identical to the example 10. considered in Example 10. Example 17: The inclination angle of the metal stream Figure 17. All the parameters of the method, a la vertical, exceeds the claim

in addition to the rate of displacement of metal from the fire, 5 2 ° / ° and the EST for the thrust pipe and the argon inlet time z ° 28 8 °.

it is the same as in example 10. Speed W

displacement corresponds to the upper claimed ALL OTHER parameters of the method correspond to those considered in example 10.

8-60

0.046

0.94M.

0.6

1.31 m / s.

PRI me R 23. Meets the conditions for casting the prototype method on a vertical continuous casting machine for casting an ingot with a cross section of 265x340 mm at a speed of 0.0108 m / s. The hydraulic diameter of the metal stream flowing out of the tundish d and displaced from the immersion tube D is 0.025 and 0.1 m, respectively. The depth of the refractory tube into the metal is 0.6 m, and the flow rate of the stream from the tundish is 2, 0 m / s

L, Chemical heterogeneity of continuous cast ingots was assessed by the degree of axial segregation of sulfur, and physical heterogeneity by the macrostructure of their transverse templates.

The results of these analyzes for all considered examples are presented in the table.

The table shows that the minimum extent of the columnar crystal zone and the smallest degree of axial segregation of sulfur are achieved in ingots cast on vertical and curvilinear machines, respectively, according to examples 9 and 18, in which the rate of displacement of metal from the refractory pipe exceeded the upper limit. , and all other required parameters were optimal.

However, these ingots were affected by bloody segregation, which led to the rejection of these ingots.

Casting metal according to examples 19 and 22. providing the angle of inclination of the axis of the metal jet displaced from the refractory pipe to the vertical, respectively, below and above the claimed limit, was not possible as a result of the metal breaking through the ingot shell at the outlet of the crystallizer due to its one-sided washing off.

Indicators of the macrostructure and chemical heterogeneity of ingots cast in examples 3, 4, 7, 8, 12, 13, 17. 17. 20. 21. Each of which implemented one of the casting parameters at the lower or upper required limits at optimal values the rest, somewhat worse, were obtained under the casting conditions of examples 1, 10, which correspond to the optimal values of all the proposed parameters, respectively, on machines of vertical and curvilinear type.

Using the proposed method of continuous casting of ingots in comparison with the prototype, while reducing the length of the column zone, the rate of metal leakage from the immersion pipe is (3-4) d / D of the flow of the metal stream when it flows out of the tundish and is equal to on average

o, 3.5 -2 1.75 m / s.

The distance along the ingot axis from the metal meniscus in the mold to the point of contact between the vortex and the hard shell of the ingot

0.046

0.77 fA

crystals and the degree of axial segregation of sulfur to avoid the breakthrough of liquid metal through the shell of the ingot below

Claims (2)

the crystallizer and bloody segregation in connection with the ingot saturation with gas, which ensures a reduction in rejects by 0.13-0.18%. Claims 1. Method for continuous casting of ingots on installations of vertical and curvilinear type, including the flow of liquid metal from the tundish into the mold through a submersible refractory tube, pulsation mixing metal in the mold by periodically filling and displacing the metal with gas from the refractory tube, forming an ingot and pulling it out of the mold, characterized in that. what with the purpose improving the quality of the ingot by reducing its chemical and physical heterogeneity, the displacement of metal from the refractory pipe is produced by a jet with an initial hydraulic diameter determined by the dependence 2.2d, 5a 0.0115h - blpj -0.016 BUT/ with speed d) jets within 40 oh,  but Li- h / f 0.6   VD IFJ at, and at an, the speed and is determined from the expression 0 16s / Ph VfJ pi ft; L2 - h D 0.6 where Li is the distance along the axis of the ingot from the metal meniscus to the zone of contact between the gas-containing vortex and the ingot shell, defined by the ratio 2k LI4I f. N 1 / l 4 ° r ° 092 (2D a 0 023h1 0.046 L2 is the distance along the axis of the ingot from the metal meniscus to the point of penetration of the gas-containing vortex into the liquid phase, determined from , 017R (90-80 V005); d is the hydraulic diameter of the metal jet flowing from the tundish, m; a is the thickness of the ingot, m; h is the depth of immersion of the refractory pipe in the metal, m; K - metal solidification coefficient, m / min ° 5; V- metal casting speed, m / min; R is the radius of curvature of the ingot axis, m; and 88 48 100 1.26 1.26 1.26 1.26 1.75 , 20 6 ° 13 e ° 0.046 f, F is the cross-sectional area of the metal jet flowing from the tundish and displaced from the refractory tube, respectively, m2; s is the cross-sectional area of the ingot, m; P is the perimeter of the ingot cross section, m. 2. A method according to claim 1, characterized in that, in curvilinear installations, a jet of metal displaced from the refractory tube is directed toward the curvature of the ingot at an angle a to the vertical, equal to (24-28), where 24-28 is empirical co-15 effect 1.96 1.96 1.96 1.96 that liquation Casting is discontinued due to the breakthrough of the liquid metal through the shell of an ingot of a larger radius of 13.25V I.O55 Casting ceased due to metal breakthrough through the shell of the ingot of a smaller radius Cracking and metal breakthroughs Sch / g.2 Editor M.Kelemes №4 Compiled by V. Yakovlev Tehred M.MorgentalKorrektor O.Kundrik