JP2016073990A - Continuous casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To materialize casting of a through-put of 10 to 15 [ton/min] without using a superconducting magnet.MEANS FOR SOLVING THE PROBLEM: In a continuous casting method, when heat energy per unit volume/unit time of molten steel discharge flow is Eand energy per unit volume necessary for dissolving a coagulation shell on a position to which the discharge flow comes into collision is E, the reciprocal (1/P) of the maximum value Pin a casting mold of P calculated by P=E/Egets to 0.38[s].SELECTED DRAWING: Figure 3

Description

  The present invention relates to a continuous casting method for realizing continuous casting with high throughput using a continuous casting apparatus having an electromagnetic brake.

The continuous casting equipment is equipment for producing slabs, billets and the like by casting molten metal.
In continuous casting of a slab, molten steel stored in a tundish is supplied to the mold through an immersion nozzle connected to the bottom of the tundish. For example, an immersion nozzle having two discharge holes is widely used, and there is one in which molten steel at high speed and high temperature is ejected through the discharge holes in parallel with the mold long side direction.

First, the difference between “casting speed” and “throughput”, which are important terms in describing the present invention, will be described.
The casting speed is a slab drawing speed in a continuous casting machine, and is a physical quantity expressed in units of [m / min]. On the other hand, the throughput is the weight of a slab produced per minute, and is a physical quantity expressed in units of [ton / min].
Accordingly, there is a relationship between throughput and casting speed: throughput [ton / min] = slab cross-sectional area [m ² ] × casting speed [m / min] × specific gravity (7.8) [ton / m ³ ]. It holds.

  Now, the throughput in a general continuous casting apparatus is 5 [ton / min] or less, but it is desired to realize a higher throughput from the viewpoint of improving productivity. For example, if casting exceeding 10 [ton / min] is possible, the number of continuous casting machines for achieving the same production amount can be halved, and the cost can be significantly reduced.

However, the biggest problem that must be solved in order to realize casting exceeding 10 [ton / min] is prevention of breakout.
If the flow velocity of the molten steel ejected from the discharge hole becomes high, the solidified shell on the short side of the mold will be remelted. However, if this solidified shell is melted, a breakout occurs and it is impossible to cast. Because it becomes.

  In order to prevent remelting of the solidified shell due to an increase in the flow rate of molten steel, an electromagnetic force control method called an electromagnetic brake that applies a static magnetic field in a direction perpendicular to the mold thickness is effective.

  In Patent Document 2, for the purpose of stably producing a maintenance-free cast slab in high-speed continuous casting, a static magnetic field is applied between opposing side walls of a continuous casting mold, and the continuous casting is performed through an immersion nozzle. In controlling the jet of molten steel to be fed into the casting mold, molten steel is fed into the continuous casting mold with a throughput of 6 [ton / min] or more, and electromagnets are arranged above and below the immersion nozzle, respectively, for continuous casting. A magnetic field having a magnetic flux density of at least 0.5 [T] at the meniscus portion of the casting mold, and a magnetic flux density of 0.5 [T] or more in the lower region of the molten steel jet ejected from the discharge port of the immersion nozzle A method of simultaneously applying a static magnetic field is disclosed.

That is, the method disclosed in Patent Document 2 uses a superconducting magnet to apply a strong magnetic flux density of 0.5 to 5.0 T, thereby providing a casting technique with a throughput of 6 to 10 [ton / min]. Disclosure. The magnetic flux density generated by an electromagnetic brake of a general continuous casting machine is about 0.1 to 0.5 [T].
However, since the method disclosed in Patent Document 1 uses a superconducting magnet, a large facility for cooling the superconductor with liquid helium is required, which cannot be easily introduced, and is very difficult to maintain. There is a problem that a lot of labor is required.

Patent Document 1 discloses that the carbon content is 0 for the purpose of completely preventing remeltable breakout caused by remelting of the solidified shell at the short side of the slab, which is likely to occur during the casting of medium carbon steel. Continuous casting of 0.08 to 0.16 [mass%] medium carbon steel using a mold whose thickness corresponding to the slab thickness exceeds 240 [mm] and whose length in the casting direction is 1.1 m or less In the case of using a mold flux having CaO / SiO ₂ of 1.2 to 2.5 and a solidification temperature of 1200 to 1280 [° C.], and an immersion nozzle having a discharge hole directed downward from the horizontal direction, the magnetic pole The static magnetic field application device is disposed with the center position in the casting direction below the discharge hole, and a static magnetic field with a magnetic field strength of 0.15 [T] or more applied to the molten steel at the center in the mold thickness direction. Slab solidity index A is 190 or more It discloses a method of casting under conditions to be.

  However, with the method disclosed in Patent Document 1, it is difficult to achieve a throughput exceeding 10 [ton / min].

JP 2010-240711 A JP 2002-316242 A

  An object of the present invention is to realize casting with a throughput of 10 [ton / min] to 15 [ton / min] without using a superconducting magnet.

When the thermal energy per unit volume and unit time of the molten steel discharge flow is E _f , and the energy per unit volume required to dissolve the solidified shell at the position where the discharge flow collides is E _s , P = E _f / E _s (Formula 1)
The physical quantity corresponding to the time required for the solidified shell to dissolve again (hereinafter referred to as “solidified shell remelting time”) is the reciprocal (1 / P _max ) of the maximum value P _max in the mold of P calculated by The inventors have found that.

Further, the inventors calculate P _max based on the data at the time of occurrence of breakout that has already been experienced, and if P _max is 2.66 or less, breakout does not occur, in other words, solidification shell remelting It has been found that by creating a continuous casting facility in which the time is larger than 1 / 2.66≈0.38 [s], it becomes a guideline for preventing the occurrence of breakout.
The present invention has been made based on the above findings, and the gist thereof is as follows.

(1) A continuous casting method of casting at a throughput of 10 [ton / min] to 15 [ton / min] using a continuous casting apparatus having an electromagnetic brake having two iron cores on the long side of the mold. And
When the thermal energy per unit volume and unit time of the molten steel discharge flow is E _f , and the energy per unit volume required to dissolve the solidified shell at the position where the discharge flow collides is E _s , P = E _f / E _s (Formula 1)
The continuous casting method is characterized in that the reciprocal (1 / P _max ) of the maximum value P _max in the mold of P calculated by the above is 0.38 [s] or more.

(2) A continuous casting method of casting at a throughput of 10 [ton / min] to 15 [ton / min] using a continuous casting apparatus having an electromagnetic brake having two iron cores on the long side of the mold. From the iron core center position (x ₀ , y ₀ ) [mm] of the electromagnetic brake, the discharge hole lower end position (x ₁ , y ₁ ) [mm] and the discharge hole angle α of the immersion nozzle, h = y ₁ + (x ₀₋ x ₁ ) tan α−y ₀ (Formula 2)
The distance h in the mold depth direction calculated as follows is 0 [mm] or more,
The magnetic flux density at the mold thickness center is 0.4 [T] to 0.5 [T].
A continuous casting method characterized by that.

(3) The continuous casting method according to (2), wherein the upper end of the discharge hole of the immersion nozzle is at a position of 220 to 400 [mm] from the molten metal surface.

  The method of the present invention has a remarkable effect that continuous casting with a throughput of 10 [ton / min] to 15 [ton / min] can be realized without using a superconducting magnet.

It is a schematic diagram explaining the inside of the casting_mold | template of a continuous casting apparatus. It is a figure explaining the relationship between magnetic flux density and solidification shell remelting time (1 / _Pmax ). It is a figure explaining the continuous casting apparatus which enforces the method of this invention in detail. It is a figure explaining the flow change in a casting_mold | template at the time of changing the discharge hole angle (alpha) by the result of numerical analysis simulation. It is a figure explaining the relationship between mold depth direction distance h and solidification shell remelting time (1 / _Pmax ). It is a figure explaining the relationship between a throughput and the solidification shell remelting time (1 / P _max ) (discharge hole angle α = 35 [°], maximum magnetic flux density 0.45T). It is a figure explaining the relationship between magnetic flux density and solidification shell remelting time (1 / _Pmax ) (discharge hole angle (alpha) = 35 [degree]). It is a figure explaining the example of a numerical analysis simulation result. It is the figure which expanded a part of FIG. It is the graph which calculated and plotted re-solubility index P [1 / s] using the example of a numerical analysis simulation result.

  In the embodiment of the present invention, continuous casting is performed at a throughput of 10 [ton / min] to 15 [ton / min] using a continuous casting apparatus having an electromagnetic brake having two iron cores on the long side of the mold. Is the method.

(First embodiment)
The first embodiment is a method in which the solidified shell dissolution time described below is 0.38 [s] or longer.

[Solidification shell dissolution time]
The solidification shell melting time is defined as the heat energy per unit volume and unit time of the molten steel discharge flow when continuous casting is performed using a continuous casting facility having an electromagnetic brake having two iron cores on the long side of the mold. _f = E _f / E _s (Equation 1) where E _{s is} the energy per unit volume required to dissolve the solidified shell at the position where the discharge flow collides
_Is the reciprocal (1 / P _max ) of the maximum value P _max in the mold of the resolubility index P calculated by

<Resolubility index P [1 / s]>
FIG. 1 is a schematic view for explaining the inside of a mold of a continuous casting apparatus.
FIG. 1 describes the right side of a symmetrical device, but the left side has similar equipment and the like.
In FIG. 1, 1 is the origin (0, 0) [mm], 21 is the mold short side, 4 is the immersion nozzle, 5 is the molten metal surface, 6 is the discharge hole, 61 is the discharge hole angle, 62 is the upper end of the discharge hole, 63 Is a lower end of the discharge hole (x ₁ , y ₁ ) [mm], 64 is a discharge flow, 7 is a solidified shell, the casting direction is y [mm], the mold width direction is x [mm], and the mold thickness direction is z [ mm].
The molten steel discharged from the discharge hole lower end 63 of the immersion nozzle 4 becomes a discharge flow 64 and flows in the direction of the discharge hole angle 61, collides with the solidified shell 7 and remelts the solidified shell.

Now, the thermal energy _{E f} per unit time striking the solidified shell at a very small area (ΔyΔz) is molten steel [rho _L density ^[kg / m 3], the specific heat of _{C P} [J / kg], the collision velocity of u [m / s], it can be expressed as molten steel T temperature [K], the a _{T s} and liquidus temperature [K] (equation 11).
_{E f = ρ L C P u} (T-T s) ΔyΔz = ρ L C P uΔTΔyΔz ... ( Equation 11)

When the thickness of the solidified shell at this position is Γ [m], the energy E _s for dissolving the solidified shell when the solidified shell is adiabatic and stationary is ρ _S is the specific gravity of the solidified shell [kg / m ³ ], ΔH is the latent heat of fusion [J / kg] and can be expressed as (Equation 12).
E _s = ρ _s ΔHΓΔyΔz (Expression 12)
Further, if (Equation 1) is used and the density (ρ _L , ρ _S ) of the liquid phase and the solid phase is small and equal, a resolubility index P can be obtained as in (Equation 13).
_{P = E f / E s =} (ρ L C P uΔTΔyΔz) / (ρ s ΔHΓΔyΔz)
_{= (C P uΔT) / (} ΔHΓ) ... ( Equation 13)
The re-solubility index P in (Equation 13) means the reciprocal of the time until the shell dissolves when the solidified shell is stationary, and the unit is [1 / s].

<Solidification time of solidified shell (1 / P _max ) [s]>
The greater the value of the re-solubility index P, the higher the risk of re-dissolution.
The remeltability index P is calculated in the mold depth direction, the maximum value is P _max , and the reciprocal (1 / P _max ) is the solidified shell remelt time [s]. That is, it is treated as a guideline for evaluating the risk of occurrence of breakout.
In obtaining the solidified shell remelting time (1 / P _max ) [s], calculation was performed by numerical analysis simulation described later using the mold conditions when breakout occurred in the past due to remelting of the solidified shell.

FIG. 2 is a diagram for explaining the relationship between the magnetic flux density and the solidification shell remelting time (1 / P _max ). Simulation was used to calculate the solidification shell remelting time (1 / P _max ) [s].
In FIG. 2, group 1 is a group in which a breakout has occurred, and group 2 is a group in which no breakout has occurred.
Breakout occurred in group 1 with a magnetic flux density of 0.21 [T] or less, and no breakout occurred in group 2 with a magnetic flux density of 0.24 [T] or more. Therefore, 0.38 [s] which is the solidification shell remelting time (1 / P _max ) [s] under the condition when the magnetic flux density of group 2 is 0.24 [T] is set as the limit value.
That is, the solidified shell remelting time (1 / P _max ) [s] is set to 0.38 [s] or more as a guideline.

<Numerical analysis simulation>
Since the molten steel in the mold is at a high temperature of about 1500 [° C.], it is difficult to know by measuring the flow rate and temperature, and at present, prediction by high-precision numerical analysis simulation is the most effective means.
By conducting a numerical analysis simulation considering the flow, heat transfer and solidification of the molten steel in the mold, the solidified shell thickness Γ [m] in the mold, the flow velocity u [m / s] colliding with the solidified shell, and the molten steel temperature T [K] can be obtained.

FIG. 8 is a diagram for explaining an example of the result of the numerical analysis simulation, and FIG. 9 is an enlarged view of a part of FIG.
8 and 9, the solidified shell thickness Γ [m] in the mold at a distance y ₂ from the molten metal surface, the flow velocity u [m / s] colliding with the solidified shell, and the molten steel temperature T [K] are read. A method will be described.
In FIG. 8, 5 is a molten metal surface, 7 is a solidified shell, 8 is a flow of molten steel (the direction of the arrow is the direction of flow, the length of the arrow indicates the flow velocity), 31 is the iron core, and 33 is the center of the iron core. , and the 9 is a measurement point _{y 2.}
The flow 8 of molten steel is indicated by an arrow, the direction of the arrow is the direction of the flow velocity, the length of the arrow represents the flow velocity, and the flow velocity reference 81 (the size of 1 [m / s]) is the upper left of FIG. It is described in.
8, the position where the distance y from the melt surface becomes y ₂ is the measurement point y _{2 (9),} is described in Figure 9 in the vicinity of the measurement point y _{2 (9)} as an enlarged view.

In FIG. 9, 9 is the measurement point y ₂ , and 71 is the thickness Γ [mm] of the solidified shell 7 at the measurement point y ₂ (9).
As shown in FIG. 9, the measurement point y ₂ (9) uses a position where the distance y from the molten metal surface is y ₂ and a position 20 [mm] from the left end of the solidified shell 7.
The flow velocity u [m / s] colliding with the solidified shell is obtained from the length of the arrow indicating the flow (8) of the molten steel at the measurement point y ₂ (9) in FIG.
The molten steel temperature T [K] is the temperature at the measurement point y ₂ (9) in FIG. 9, and T = 26 [K].
The solidified shell thickness Γ [m] in the mold is obtained as the solidified shell thickness 71 on the right side of the measurement point y ₂ (9) in FIG.
The resolubility index P [1 / s] at the measurement point y ₂ (9) is determined by the solidified shell thickness Γ [m] in the mold obtained by the above-described procedure and the flow velocity u [m / s that collides with the solidified shell. ] Using the molten steel temperature T [K]
_{P = E f / E s =} (ρ L C P uΔTΔyΔz) / (ρ s ΔHΓΔyΔz)
_{= (C P uΔT) / (} ΔHΓ)
_{= (C P u (T-} T s)) / (ΔHΓ) ... ( Equation 13)
Calculate more.

FIG. 10 is a diagram for explaining an example of values when the horizontal axis represents the distance y [m] from the molten metal surface and the vertical axis represents the resolubility index P [1 / s]. In FIG. 10, P _max can be obtained at the position of y≈0.35 [m].
Now, the inventors examined y for obtaining P _max .
In FIG. 10, since the position of y≈0.35 [m] at which P _max can be obtained is near the lower end of the immersion nozzle, the heat flux (flow velocity × temperature) is maximized near the lower end of the immersion nozzle, and P _max is given. I found. That is, in order to obtain P _max in a short time, it was found that the re-solubility index P [1 / s] should be precisely calculated in the vicinity of the lower end of the immersion nozzle.

(Second Embodiment)
In the second embodiment, the distance h in the mold depth direction, the magnetic flux density at the center of the mold thickness, and the upper end position of the discharge hole of the immersion nozzle are specified so that the solidified shell dissolution time described below is 0.38 [s] or more. It is a method to do.

[Distance h in the mold depth direction]
FIG. 3 is a diagram for explaining in detail a continuous casting apparatus for carrying out the method of the present invention.
In FIG. 3, 1 is the origin (0, 0) [mm], 2 is the mold, 21 is the mold short side, 22 is the mold long side, 3 is the electromagnetic brake, 31 is the iron core, 32 is the coil, and 33 is the center of the iron core. (X ₀ , y ₀ ) [mm], 4 is an immersion nozzle, 5 is a molten metal surface, 6 is a discharge hole, 61 is a discharge hole angle α [°], 63 is a discharge hole upper end, and 63 is a discharge hole lower end (x ₁ , Y ₁ ) [mm], the casting direction is y [mm], the mold width direction is x [mm], and the mold thickness direction is z [mm].
Since FIG. 3 is symmetrical, the right side will be mainly described in order to simplify the description, but the left side has the same equipment.

The magnetic flux density is maximized at the center position 12 of the iron core 31 of the electromagnetic brake 3.
At this time, the distance h in the mold depth direction is the iron core center position (x ₀ , y ₀ ) [mm] of the electromagnetic brake, the discharge hole lower end position (x ₁ , y ₁ ) [mm] of the immersion nozzle, and the discharge hole. From the angle α [°], h = y ₁ + (x ₀ −x ₁ ) tan α−y ₀ (Expression 2)
Is the calculated value.

<Geometric relationship>
The molten steel flow velocity ejected from the discharge hole of the immersion nozzle has a maximum value below the discharge hole.
That is, it can be considered that the discharge flow is discharged in the direction of the discharge hole angle α [°] starting from the position (x ₁ , y ₁ ).
When h> 0, the discharge flow passes below the maximum magnetic flux density position, and when h <0, the discharge flow passes above the maximum magnetic flux density position.

<Range of distance h in the mold depth direction>
The reason why the distance h in the mold depth direction is set to -20 [mm] or more will be described.
FIG. 5 shows the relationship between the distance h between the discharge flow and the maximum magnetic flux density position and the resolubility index.
From FIG. 5, when h ≧ −20 [mm], the solidified shell remelting time (1 / P _max ) [s] is 0.38 [s] or more, and casting without remelting of the solidified shell is possible. It can be judged that it is possible.

<Relationship with discharge hole angle α [°]>
FIG. 4 is a diagram for explaining the flow change in the mold when the discharge hole angle α [°] is changed by numerical analysis simulation.
For example, (x ₀ , y ₀ ) = (545, 650) [mm], (x ₁ , y ₁ ) = (87.5, 440) [mm], and the discharge hole angle α [°] is 25 [°. ], 30 [°], and 35 [°] are shown in FIGS. 4 (a), 4 (b), and 4 (c), respectively. 4 (a), 4 (b), and 4 (c), 8 is an iron core, and 33 is the center of the iron core.
4 (a), (b), and (c), it is confirmed that the smaller the discharge hole angle α [°], the easier it is for the discharge flow to flow above the mold. That is, as the discharge hole angle α [°] is smaller, h becomes smaller and it is possible to understand the tendency of the discharge flow to collide above the thin mold of the solidified shell.

[Magnetic flux density at mold thickness center]
The magnetic flux density at the mold thickness center is 0.4 [T] to 0.5 [T].
The magnetic flux density is the maximum magnetic flux density at the mold thickness center, and the magnetic flux density is maximized at the iron core center position.
For example, the cross-sectional shape of the electromagnetic brake iron core is 750 × 300 [mm], the direct current applied to the coil is 1000 [A], the number of turns of the coil is 180 [turns], and the iron core material is general. The maximum magnetic flux density at the center of the mold thickness obtained from the electromagnetic field analysis result with soft iron can be about 0.5 [T] at the center position of the electromagnetic brake iron core.
The maximum magnetic flux density at the meniscus portion at the center of the mold thickness can be about 0.01 [T].

<Range of magnetic flux density>
FIG. 7 is a diagram for explaining the result of studying the influence of the magnetic flux density of the electromagnetic brake at the discharge hole angle α = 35 [°].
From FIG. 7, when the throughput is 10.9 [ton / min] and the maximum magnetic flux density is 0.3 [T], the solidification shell remelting time (1 / P _max ) [s] is 0.38 [T]. s] or more. In addition, when the throughput is 15.5 [ton / min], if it is 0.4 [T] or more, the solidification shell remelting time (1 / P _max ) [s] is 0.38 [s] or more. .
In addition, it is difficult to apply a magnetic flux density exceeding 0.5 [T] due to the current flowing in the coil and the limit of the power supply device with a normal electromagnetic brake device.
From the above, the range of the magnetic flux density at the center of the mold thickness is appropriately 0.4 to 0.5 [T]. Preferably it is 0.4-0.5 [T].

[Discharge nozzle top end position]
The discharge hole upper end position 62 of the immersion nozzle 4 is set to 220 to 400 [mm] from the molten metal surface.
FIG. 6 is a view for explaining the relationship between the throughput and the solidification shell remelting time (1 / P _max ) (discharge hole angle α = 35 [°], maximum magnetic flux density 0.45 T).
FIG. 6 shows a graph when the discharge hole upper end position is 320 [mm] and when the discharge hole upper end position is 220 [mm].
When the immersion depth was decreased by 100 [mm], the position of the electromagnetic brake was also decreased by 100 [mm] so that h had the same value.

If the height of the discharge hole opening is 120 [mm], when the discharge hole upper end position is 320 [mm], the discharge hole lower end position is 440 [mm] and the discharge hole upper end position is 220 [mm]. ], The lower end position of the discharge hole is 340 [mm].
As the immersion nozzle depth decreases, the discharge flow collides with the short side above the thin mold of the solidified shell, so the solidified shell remelting time (1 / P _max ) [s] is shortened and breakout occurs. It becomes easy.

In FIG. 6, since the throughput at which the solidification shell remelting time (1 / P _max ) intersects the line of 0.38 [s] is the limit, the discharge hole upper end position is 220 [mm] (discharge hole lower end position is 340). [Mm]), the throughput limit is about 15.5 [ton / min], but when the discharge hole upper end position is 320 [mm] (discharge hole lower end position is 440 [mm]), the throughput limit is limited. Increases to 16 [ton / min].

Thus, the deeper the immersion depth of the immersion nozzle, the lower the risk of remelting.
However, even if it is desired to increase the immersion depth, there is a limit to the device that raises and lowers the tundish. Therefore, a depth of about 400 [mm] is usually the limit at the upper end position of the discharge hole.
Therefore, the depth of the immersion nozzle is appropriately such that the upper end position of the discharge hole is 220 to 400 [mm] from the hot water surface, and preferably the upper end position of the discharge hole is 320 to 400 [mm] from the hot water surface. .

[Example of continuous casting equipment]
A continuous casting apparatus capable of casting with a throughput of 10 [ton / min] or more is, for example, a mold having a width of 1600 [mm] × a thickness of 250 [mm], an immersion nozzle having a two-hole nozzle, and a discharge hole having a height. Although the continuous casting equipment is 120 [mm] × 100 [mm] in width, the present invention is not limited to this.

Table 1 shows the conditions and results of testing the present invention with an actual continuous casting machine.
The “immersion depth” is the discharge hole upper end position 62 of the immersion nozzle 4.
The evaluation is rejected (x) when breakout occurs or it is judged that there is a risk of breakout from the temperature measurement by the thermocouple installed in the mold. ). The cause of failure (x) is underlined.

No. 4, 9, 10, 15, 199, 22, 23, 33, and 37 are comparative examples, and were determined to be rejected (x).
No. 4, 15, 199, 22, 23, 33, and 37, it is considered that h is a negative value, and the solidification shell remelting time (1 / P _max ) is set to a value smaller than 0.38 [s]. .

No. 9 and 10, h takes a positive value, but the magnetic flux density is 0.38 [T] and does not satisfy 0.40 [T], the solidification shell remelting time (1 / P _max ) It is thought that the value was smaller than 0.38 [s].

About a comparative example, it is judged that the breakout has generate | occur | produced during a casting test, or there exists a danger that a breakout will generate | occur | produce.
On the other hand, in the example of the present invention, the solidification shell remelting time is 0.38 [s], which is acceptable (◯), which indicates that the method of the present invention is effective.

  The method of the present invention can be used for high-throughput continuous casting using a continuous casting apparatus having an electromagnetic brake.

1 ... origin (0,0), 2 ... mold, 21 ... mold short side, 22 ... mold long sides, 3 ... electromagnetic brakes, 31 ... core, 32 ... coil, 33 ... center of the core _{(x 0, y} 0) , 4 ... immersion nozzle, 5 ... molten metal surface, 6 ... discharge hole, 61 ... discharge hole angle, 62 ... discharge hole upper, 63 ... discharge hole bottom _{(x 1, y 1),} 64 ... discharge flow, 7 ... solidified shell , 71 ... solidified shell thickness, the 8 ... molten steel flow, 81 ... flow rate reference 1,82 ... velocity reference 2,9 ... measurement point _y 2.

Claims (3)

A continuous casting method for casting at a throughput of 10 [ton / min] to 15 [ton / min] using a continuous casting apparatus having an electromagnetic brake having two iron cores on the long side of the mold,
When the thermal energy per unit volume and unit time of the molten steel discharge flow is E _f , and the energy per unit volume required to dissolve the solidified shell at the position where the discharge flow collides is E _s , P = E _f / E _s (Formula 1)
The continuous casting method is characterized in that the reciprocal (1 / P _max ) of the maximum value P _max in the mold of P calculated by the above is 0.38 [s] or more. A continuous casting method for casting at a throughput of 10 [ton / min] to 15 [ton / min] using a continuous casting apparatus having an electromagnetic brake having two iron cores on the long side of the mold, From the brake iron core center position (x ₀ , y ₀ ) [mm], the discharge hole lower end position (x ₁ , y ₁ ) [mm] of the immersion nozzle and the discharge hole angle α, h = y ₁ + (x ₀ −x ₁ ) tan α-y ₀ (Formula 2)
The distance h in the mold depth direction calculated as follows is 0 [mm] or more,
The magnetic flux density at the mold thickness center is 0.4 [T] to 0.5 [T].
A continuous casting method characterized by that.   The continuous casting method according to claim 2, wherein the upper end of the discharge hole of the immersion nozzle is located at a position of 220 to 400 [mm] from the molten metal surface.