KR101443588B1 - Method for predicting pin-hole defect of slab - Google Patents

Abstract

The present invention relates to a method for predicting pinhole defects in a slab, comprising the steps of obtaining a viscosity (mold) and a casting speed (m / min) of a mold powder to be supplied to the upper end of a molten steel for lubrication of the mold and the solidification shell during continuous casting , Calculating a pinhole generation index (Ipv) by multiplying the obtained mold powder poise by a casting speed (m / min), and calculating a pinhole generation index (Ipv) by multiplying the in- Calculating a ratio Rhf, and predicting a pinhole generation rate of a slab cast using the heat flux ratio Rhf calculated in the above.

Description

METHOD FOR PREDICTING PIN-HOLE DEFECT OF SLAB [0002]

The present invention relates to a slab quality control method, and more particularly, to a slab pinhole defect predicting method for predicting a pinhole defect in a slab by using operating conditions during continuous casting.

In general, a continuous casting machine is a machine which is produced in a steel making furnace, receives molten steel transferred to a ladle by a tundish, and supplies it to a mold for a continuous casting machine to produce a cast steel having a predetermined size. The continuous casting machine includes a ladle for storing molten steel, a casting mold for casting a tundish and molten steel introduced from the tundish into a cast piece having a predetermined shape, and a plurality of casting pieces connected to the mold Of pinch rolls.

In other words, the molten steel introduced in the ladle and the tundish is formed into a cast steel having a predetermined width, thickness and shape in the mold and is conveyed through the pinch roll, and the cast steel conveyed through the pinch roll is cut by a cutter, Or a semi-finished product such as a slab, a bloom, or a billet.

In this way, grooved surface defects, i.e., pinholes, are produced on the surface of the slab produced through continuous casting. These pinholes act as defects in the steel, which may cause deterioration of steel quality.

Related prior art is Korean Patent Publication No. 2005-54058 (published on June 10, 2005, titled: martensitic stainless steel without pinhole defect).

The present invention is to provide a method for predicting a pinhole defect in a slab capable of casting a high-quality slab by anticipating and coping with pinhole defects that may occur in a mold by using operating conditions during continuous casting.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems.

In order to achieve the above object, there is provided a method for predicting pinhole defects in a slab, which comprises the steps of: (a) preparing a mold powder having a viscosity and a casting speed (m / min) for lubrication of a mold and a solidification shell during continuous casting, Respectively; Calculating a pinhole generation index (Ipv) by multiplying the obtained mold powder poise by a casting speed (m / min); Calculating an end-to-end heat flux ratio (Rhf) in the mold by substituting the pinhole generation index calculated above into the following relational expression; And estimating the pinhole generation rate of the slab cast using the heat flux ratio (Rhf) calculated above.

Relation

Here, A1, A2 and A3 are constants of the relationship between the pinhole generation index (Ipv) and the heat flux ratio (Rhf), A1 is a value of 0.040 to 0.044, A2 is a value of 0.024 to 0.027 and A3 is a value of 0.60 to 0.66 .

The predicted pinhole incidence rate is compared with a preset reference value to predict the quality of the slab to be continuously cast, and the predicted pinhole incidence rate is compared with a preset reference value. If the pinhole incidence rate exceeds the reference value, The viscosity of the powder can be increased to reduce the degree of occurrence of pinholes.

Wherein the molten steel is an extremely low carbon steel having a carbon content of 0.03 wt% or less, the thickness T of the slab cast in the above is 200 to 300 mm, the width W of the slab is 1000 to 2000 mm, poise) is from 1.0 to 3.0 poise, and the casting speed can be controlled from 1.0 to 2.0 m / min.

As described above, the present invention can predict the degree of surface defects of a slab cast through a continuous casting condition in advance and improve the surface quality of the slab to be cast by coping with it.

1 is a conceptual view showing a continuous casting machine according to an embodiment of the present invention, focusing on the flow of molten steel.
Fig. 2 is a conceptual diagram showing the distribution of the molten steel M in the mold and its adjacent portion in Fig. 1. Fig.
3 is a photograph showing a pinhole defect of a slab produced by continuous casting in connection with the present invention.
4 is a view illustrating an apparatus for predicting pinhole defects in a slab according to an embodiment of the present invention.
5 is a flowchart illustrating a pinhole defect predicting process according to an embodiment of the present invention.
6 and 7 are graphs showing the relationship between the pinhole generation index, the heat flux ratio, and the pinhole incidence rate according to the embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference symbols whenever possible. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

1 is a conceptual view showing a continuous casting machine according to an embodiment of the present invention, focusing on the flow of molten steel.

Continuous casting is a casting process in which a molten metal is continuously cast into a bottomless mold while continuously drawing a steel ingot or steel ingot. Continuous casting is used to manufacture slabs, blooms and billets, which are mainly rolled materials, and long products of simple cross-section such as square, rectangle, and circle.

The shape of a continuous casting machine is classified into a vertical type and a vertical bending type. In Fig. 1, a vertical bending type is illustrated.

1, a continuous casting machine may include a ladle 10 and a tundish 20, a mold 30, secondary cooling bands 60 and 65, and a pinch roll 70.

A tundish 20 is a container for receiving molten metal from a ladle 10 and supplying molten metal to a mold 30. In the tundish 20, the supply rate of the molten metal flowing into the mold 30 is controlled, the molten metal is distributed to each mold 30, the molten metal is stored, and the slag and the nonmetallic inclusions are separated.

Mold 30 is typically made of water-cooled copper and allows the molten steel taken to be first cooled. The mold 30 has a pair of structurally opposed faces open to form a hollow portion for receiving molten steel. In the case of manufacturing the slab, the mold 30 includes a pair of barriers and a pair of end walls connecting the barriers. Here, the end wall has a smaller area than the barrier. The walls, mainly the walls, of the mold 30 can be rotated to be away from or close to each other to have a certain level of taper. This taper is set to compensate for the shrinkage due to the solidification of the molten steel M in the mold 30. The degree of solidification of the molten steel (M) varies depending on the carbon content according to the steel type, the type of the mold powder (strong cooling type Vs and cold type), the casting speed and the like.

The mold 30 is formed such that a solidified shell or a solidified shell 81 is formed so as to maintain the shape of the casting pluck pulled out from the mold 30 and to prevent the molten metal from being hardly outflowed from flowing out. . The water-cooling structure includes a method using a copper tube, a method of water-cooling the copper block, and a method of assembling a copper tube having a water-cooling groove.

The mold 30 is oscillated by the oscillator 40 to prevent the molten steel from sticking to the wall surface of the mold. A lubricant is used to reduce the friction between the mold 30 and the solidification shell 81 during oscillation and to prevent burning. As the lubricant, there are a flat oil to be sprayed and a mold powder added to the surface of the molten metal in the mold 30. The mold powder is added to the molten metal in the mold 30 to become slag and the lubricant of the mold 30 and the solidification shell 81 as well as the prevention of oxidation and oxidation of molten metal in the mold 30, But also functions to absorb nonmetallic inclusions that float on the surface. A powder feeder (50) is installed to feed the mold powder into the mold (30). The portion of the powder feeder 50 that discharges the mold powder is directed to the inlet of the mold 30.

The secondary cooling bands 60 and 65 further cool the molten steel that has been primarily cooled in the mold 30. The primary cooled molten steel is directly cooled by the spraying means 65 for spraying water while being maintained by the support roll 60 so that the coagulation angle is not deformed. Most of the solidification of the cast steel is accomplished by the secondary cooling.

The pulling device employs a multi-drive type or the like in which a plurality of pinch rolls (70) are used so as to pull out the casting slides without slipping. The pinch roll 70 pulls the solidified leading end portion of the molten steel in the casting direction so that molten steel passing through the mold 30 can be continuously moved in the casting direction.

In the continuous casting machine constructed as described above, the molten steel M contained in the ladle 10 flows into the tundish 20. For this flow, the ladle 10 is provided with a shroud nozzle 15 extending toward the tundish 20. The shroud nozzle 15 extends into the molten steel in the tundish 20 so that the molten steel M is not exposed to the air to be oxidized and nitrided.

The molten steel M in the tundish 20 is caused to flow into the mold 30 by the submerged entry nozzle 25 extending into the mold 30. The immersion nozzle 25 is disposed at the center of the mold 30 so that the flow of the molten steel M discharged from both the discharge ports of the immersion nozzle 25 can be made symmetrical. The start, discharge speed and interruption of the discharge of the molten steel M through the immersion nozzle 25 are determined by a stopper 21 provided on the tundish 20 in correspondence with the immersion nozzle 25. [ Specifically, the stopper 21 can be vertically moved along the same line as that of the immersion nozzle 25 so as to open and close the inlet of the immersion nozzle 25. The control of the flow of the molten steel M through the immersion nozzle 25 may be performed by a slide gate method different from the stopper method. The slide gate controls the discharge flow rate of the molten steel (M) through the immersion nozzle (25) while the plate material slides horizontally in the tundish (20).

Molten steel (M) in the mold (30) starts to solidify from a portion in contact with the wall surface of the mold (30). This is because the periphery of the molten steel M is liable to lose heat by the water-cooled mold 30. The rear portion along the casting direction of the cast slab 80 is formed into a shape in which the non-solidified molten steel 82 is wrapped in the solidifying shell 81 by the method in which the peripheral portion first coagulates.

The non-solidified molten steel 82 moves together with the solidifying shell 81 in the casting direction as the pinch roll 70 (Fig. 1) pulls the tip end portion 83 of the fully-solidified cast slab 80. The non-solidified molten steel (82) is cooled by the spraying means (65) for spraying the cooling water in the up-shifting process. This causes the thickness of the non-solidified molten steel (82) to gradually decrease in the cast steel (80). When the cast steel 80 reaches one point 85, the cast steel 80 is filled with the solidified shell 81 as a whole. The solidification casting 80 having been solidified is cut to a predetermined size at the cutting point 91 and is divided into a slab P such as a slab or the like.

The shape of the molten steel M in the mold 30 and its adjacent portion will be described with reference to Fig. Fig. 2 is a conceptual diagram showing the distribution pattern of the molten steel M in the mold 30 and its adjacent portion in Fig. 1. Fig.

Referring to FIG. 2, a pair of discharge ports 25a are formed on the end sides of the immersion nozzle 25 on the left and right sides in the drawing. It is assumed that the shapes of the mold 30 and the immersion nozzle 25 are symmetrical with respect to the center line C, and only the left side is shown in the drawing.

The molten steel M discharged along with the argon (Ar) gas at the discharge port 25a draws a locus that flows in the upward direction A1 and the downward direction A2 as indicated by arrows A1 and A2 do.

A mold powder layer 51 is formed on the upper portion of the mold 30 by the mold powder supplied from the powder feeder 50 (see Fig. 1). The mold powder layer 51 may include a layer existing in the form in which the mold powder is supplied and a layer sintered by the heat of the molten steel M (the sintered layer is formed closer to the non-solidified molten steel 82). A slag layer or a liquid flowing layer 52 formed by melting the mold powder by the molten steel M is present below the mold powder layer 51. The liquid flowing layer (52) maintains the temperature of the molten steel (M) in the mold (30) and blocks the penetration of foreign matter. A part of the mold powder layer 51 solidifies at the wall surface of the mold 30 to form the lubricant layer 53. [ The lubricating layer 53 functions to lubricate the solidifying shell 81 so that it does not adhere to the mold 30.

The thickness of the solidifying shell 81 becomes thicker along the casting direction. The portion of the solidifying shell 81 located in the mold 30 is thin and an oscillation mark 87 is formed according to the oscillation of the mold 30. [ The solidifying shell 81 is supported by the support roll 60 and thickened by the spraying means 65 for spraying water. The solidifying shell 81 is thickened, and a bulging region 88 is formed in which a portion protrudes convexly.

The mold powder used in the continuous casting process flows in the form of a liquid between the solidifying shell 81 and the mold 30 during casting to transfer heat and lubricate between the mold 30 and the solidifying shell 81 . Carbon is used to control the rate at which the mold powder changes into liquid phase. However, the carbon in the mold powder is burned by the heat provided by the molten steel, and carbon monoxide (CO) is generated by the combustion reaction. The carbon monoxide thus generated is trapped in the solidifying shell 81 during casting, causing a bubble defect such as a pin hole on the surface of the cast slab as shown in FIG. In order to cast various kinds of steel, the mold powder with different physical properties is used in consideration of the solidification characteristics of the steel species.

These pinholes are generated by the argon gas supplied for stirring in the continuous casting process or by the gas generated by the component reaction in the molten steel. When the slab having the pinhole defect is rolled in the hot rolling process, it deforms into a defect accompanied by the bubble shape, and the bubble type defect develops into a defect of a silver defect type in the final cold rolling coil. Therefore, it is necessary to predict and manage the pinhole defects formed on the surface of the slab as disclosed in the present invention.

4 is a block diagram of an apparatus for predicting pinhole defects in a solidification shell according to an embodiment of the present invention. The prediction apparatus 100 includes a storage unit 110, an input unit 130, a main speed detection unit 150, a display unit 170, And a control unit (190).

The storage unit 110 stores at least one operating parameter data of at least one of a steel type collected or inputted from the outside, thickness and width of the slab, casting speed, and physical properties of the mold powder. Here, the physical properties of the mold powder may include poise, C total, CO ₂ generation amount, and LOI (loss of ignition).

The input unit 130 receives and sets data on various operating parameters including the type of steel, the viscosity of the mold powder, the width and thickness of the slab, and the like.

The peripheral speed detecting unit 150 detects the casting speed in real time through the number of revolutions of the pinch roll 70 and stores the detected casting speed in the storage unit 110 according to the control signal. Here, the casting speed may be detected in real time through the main speed detector 150, but it may be received from a user directly through the input unit 130 or from a system for controlling the speed of the pinch roll 70.

The display unit 170 displays a graphical user interface (GUI) screen for inputting various operational parameters, pinhole defect prediction results of slabs, and pinhole incidence rates in characters or graphs.

)를 계산하게 된다. 여기서, 단변은 몰드 측면의 짧은 폭을 갖는 면을 의미하고, 장변은 몰드 전후의 긴 폭을 갖는 면을 의미한다.The control unit 190 calculates the pinhole generation index using the viscosity of the mold powder stored in the storage unit 110 and the casting speed, and calculates the end / long side heat flux ratio in the mold using the calculated pinhole generation index. The control unit 190 can obtain the pinhole incidence rate using the calculated heat flux ratio and estimate the degree of pinhole generation of the slab with the obtained pinhole incidence rate. For example, the control unit 190 calculates the pinhole generation index by multiplying the viscosity of the mold powder by the casting speed, substitutes the calculated pinhole generation index into the set relational expression, and calculates the heat flux ratios in the mold.

). Here, the short side means a face having a short width on the side of the mold, and the long side means a face having a long width before and after the mold.

The control unit 190 calculates the pinhole generation index using the casting speed set in the storage unit 110 through the input unit 130 or the pinhole generation index using the casting speed inputted through the main speed detector 150 in real time . In this case, the viscosity of the mold powder according to the type of steel can be used as the value stored in the storage unit 110 in both of the two methods.

Table 1 below shows the viscosity of the mold powder used for each steel type. In the case of the present invention, the thickness (T) of the slab cast through the mold is 200 to 300 mm and the width (W) of the slab is 1000 to 2000 mm, the carbon content of the molten steel is extremely low carbon steel of 0.03 wt% , The casting speed is 1.0 to 2.0 m / min, and the viscosity of the mold powder is 1.0 to 3.0 poise. If the steel grade, casting speed, mold powder viscosity, and slab specification deviate from each other, a large error occurs in the pinhole generation index and pinhole generation rate due to the prediction relation.

Table 1

That is, the physical properties and the component content of the mold powder may be different depending on the type of the steel. Basically, the physical properties of the mold powder may include basicity, viscosity, C total, CO ₂ generation amount and LOI. The components of these mold powders are provided basically in the composition table of the mold powder.

In the present invention, the physical properties of the mold powder used for the pinhole generation index are viscosities, and such a viscosity may vary according to the type of the steel as shown in Table 1.

As shown in the flow chart of FIG. 5, the method of predicting pinhole defects of a slab of the present invention includes steps S10 and S10 of acquiring the poise and casting speed (m / min) of mold powder during continuous casting, (S30) of calculating an end-to-end heat flux ratio in the mold (S30), estimating a pinhole generation rate of a slab cast using the calculated heat flux ratio (S40), and estimating Adjusting the viscosity of the mold powder or the casting speed to adjust the degree of pinhole generation (S50).

More specifically, when continuous casting is started in the continuous casting machine, the control unit 190 obtains the viscosity (mold) of the mold powder and the casting speed (m / min), respectively (S10). The mold powder is put into the upper end of the molten steel for lubrication of the mold 30 and the solidification shell 81 as shown in Figs. 1 and 2. The control unit 190 can receive the viscosity of the mold powder through the storage unit 110 or the input unit 130 and the casting speed can be provided through the storage unit 110 or the peripheral speed detection unit 150. [

The poise of the mold powder is determined according to the component content of the mold powder prepared in advance. When the mold powder has a high poise, the poise of the mold powder is prevented from being oxidized and retained in the mold 30, The function of absorption is improved while the lubrication of the mold 30 and the solidification shell 81 is lowered and if the viscosity of the mold powder is low, it is possible to prevent the oxidation of the molten steel in the mold 30, The function of absorption of the emerging nonmetallic inclusions is lowered, while the lubrication of the mold 30 and the solidification shell 81 is improved, so that the viscosity of the mold powder is preferably prepared to maintain an appropriate level. Therefore, the mold powder in the continuous casting of the present invention is prepared in a viscosity within a range of 1.0 to 3.0 poise.

The casting speed (m / min) is a rate at which solidified molten steel escapes from the mold 30, and its unit is m / min. The casting speed affects the time the molten steel stays inside the mold 30, which affects the degree to which the molten steel solidifies in the mold 30. That is, the longer the casting speed is, the shorter the time for the molten steel to stay in the mold 30, and if the casting speed is excessively high, the coagulating shell 81 can be discharged to the casting 80 will be. On the contrary, the slower the casting speed, the longer the time for the molten steel to stay inside the mold 30, and if the casting speed is excessively slow, the coagulating shell 81 may be discharged to the casting 80 in an excessively coagulated state It is. Therefore, the casting speed is preferably controlled to an appropriate level, and the casting speed (m / min) of the present invention is limited to the range of 1.0 to 2.0 m / min.

Next, the control unit 190 calculates the pinhole generation index using the obtained mold powder poise and the casting speed (m / min) (S20). At this time, the pinhole generation index can be calculated by multiplying the viscosity of the mold powder (poise) by the casting speed (m / min).

을 의미한다.Subsequently, the calculated pinhole generation index Ipv is substituted into the following relational expression 1 to calculate the in-mold end / long-side heat flux ratio Rhf (S30). The heat flux ratios in the mold are

.

Relationship 1

^{Rhf = -A1 × Ipv 2 + A2} × Ipv + A3

Wherein A 1 is a value between 0.040 and 0.044, A 2 is a value between 0.024 and 0.027, A 3 is a value between 0.60 and 0.66 Lt; / RTI >

The above relational expression 1 is derived from the correlation between the pinhole generation index and the heat flux ratio in FIG. The pinhole generation index is a value obtained by multiplying the viscosity of the mold powder by the casting speed (m / min) as described above. The viscosity of the mold powder of the present invention is a value between 1.0 and 3.0 poise, Considering that the speed is between 1.0 and 2.0 m / min, the pinhole generation index of the present invention has a value between 1 and 6.0.

That is, FIG. 6 is a graph showing the heat flux ratio according to the range of the pinhole generation index of 1 to 6.0, where the dot is the actual data and the solid line is the predictive model fitted with the actual data nonlinearly, (R ² = 0.8823).

Here, the coefficient A1 according to the correlation between the pinhole generation index and the heat flux ratio may preferably be '0.0421', A2 may preferably be '0.251', and A3 may preferably be '0.637' have.

The control unit 190 uses the heat flux ratio to calculate the pinhole generation rate Pph [%] as shown in the following relational expression (2) (S40).

Relation 2

Pph [%] = B1 × Rhf 2 - B2 × Rhf + B3

B1 is a value between 0.0045 and 0.0051, B2 is a value between 0.029 and 0.033, and B3 is a value between 0.28 and 0.30 .

The above relational expression 2 is derived from the correlation between the heat flux ratio and the pinhole incidence rate in FIG. On the other hand, the pinhole grades of the slab can be arbitrarily classified according to the degree of actual pinhole defect, and the degree of pinhole defect is classified as grades 1 to 5 (meaning that the degree of pinhole defects increases from 1 to 5) , But if it is below grade 2, it can be sold as a genuine product, but if it exceeds the grade 2, even if scalloping the slab, some pinholes remain, which may cause problems in sales. Here, the second grade is a case where the pinhole incidence is about 25% or less.

That is, FIG. 7 is a graph showing the pinhole incidence according to the range of the heat flux ratio of 0.89 to 1.07, where dots are actual data and solid lines are nonlinear fitting models of actual data, R ² = 0.8122). Here, the coefficient B1 according to the correlation between the heat flux ratio and the pinhole incidence rate may preferably be 0.0048, B2 may preferably be 0.0313, and B3 may preferably be 0.2896 have.

7, it can be seen that the rate of occurrence of pinholes is less than or equal to 25%, which is the second grade, when the in-mold end / long side heat flux ratio is approximately 0.90 or more to 1.00 or less.

Thereafter, the control unit 190 predicts the quality of the slab cast through the mold by comparing the calculated pinhole incidence with a preset reference value. That is, the control unit 190 compares the predicted pinhole incidence with a preset reference value, and if the pinhole incidence exceeds the reference value, the casting speed or the viscosity of the mold powder is increased to reduce the degree of occurrence of pinholes (S50) . Specifically, when the pinhole incidence rate exceeds the reference value, it is judged as a failure, and when the pinhole incidence rate is lower than the reference value, it is judged as good. Here, the reference value may be '25' [%].

Further, when the quality of the slab to be cast exceeds the reference value, the control unit 190 raises the viscosity of the mold powder used for continuous casting or raises the casting speed (m / min) of the continuous casting machine The degree of pinhole generation can be reduced. Specifically, when there is a limitation of the casting speed (m / min), the mold powder viscosity poise is increased, and when the mold powder having a constant viscosity is used, the casting speed (m / min) is increased .

This makes it possible to control the degree of occurrence of pinhole defects on the surface of the cast slab to be less than or equal to grade 2 (the pinhole generation rate is 25.0% or less) at the time of slab casting using an extremely low carbon steel having a carbon content of 0.03 wt% .

INDUSTRIAL APPLICABILITY As described above, the present invention can predict the degree of surface defects of a slab cast through operating conditions during continuous casting in advance and improve the surface quality of the slab to be cast by appropriately coping with it.

The method for predicting the pinhole defect of the slab is not limited to the construction and the operation of the embodiments described above. The embodiments may be configured so that all or some of the embodiments may be selectively combined so that various modifications may be made.

10: Ladle 15: Shroud nozzle
20: tundish 25: immersion nozzle
30: Mold 40: Mold oscillator
50: Powder feeder 60: Support roll
65: Spray means 70: Pinch roll
80: Casting Casting 81: Solidification Shell
82: non-solidified molten steel 83:
110: storage unit 130: input unit
150: Main speed detecting unit 170:
190: control unit

Claims (7)

Obtaining the viscosity (mold) and casting speed (m / min) of the mold powder to be supplied to the upper end of the molten steel for lubrication of the mold and the solidification shell during continuous casting;
Calculating a pinhole generation index (Ipv) by multiplying the obtained mold powder poise by a casting speed (m / min);
Calculating an in-mold end / long side heat flux ratio (Rhf) by substituting the pinhole generation index calculated above into the following relational expression 1; And
And estimating a pinhole generation rate of the slab cast according to the following relational expression (2) using the heat flux ratio (Rhf) calculated above.
Relationship 1
^{Rhf = -A1 × Ipv 2 + A2} × Ipv + A3
Here, A1, A2 and A3 are constants of the relationship between the pinhole generation index (Ipv) and the heat flux ratio (Rhf), A1 is a value of 0.040 to 0.044, A2 is a value of 0.024 to 0.027 and A3 is a value of 0.60 to 0.66 .
Relation 2
Pph [%] = B1 × Rhf 2 - B2 × Rhf + B3
Here, B1, B2 and B3 are constant constants of the heat flux ratio (Rhf) and the pinhole generation rate (Pph), B1 is a value of 0.0045 to 0.0051, B2 is a value of 0.029 to 0.033, and B3 is a value of 0.28 to 0.30.
The method according to claim 1,
And comparing the predicted pinhole incidence rate with a preset reference value to predict the quality of the slab to be continuously cast.
The method according to claim 1,
Comparing the predicted pinhole incidence with a preset reference value and increasing the casting speed or the viscosity of the mold powder when the pinhole incidence rate exceeds a reference value to reduce the occurrence of pinholes.
delete The method according to claim 1,
Wherein the molten steel is a very low carbon steel having a carbon content exceeding 0 wt% to 0.03 wt%.
The method according to claim 1,
Wherein the thickness (T) of the slab cast in the above is 200 to 300 mm and the width (W) of the slab is 1000 to 2000 mm.
The method according to claim 1,
Wherein the molding powder has a viscosity of 1.0 to 3.0 poise and a casting speed of 1.0 to 2.0 m / min.

Images