CN112584947A - Method for starting continuous casting of steel - Google Patents
Method for starting continuous casting of steel Download PDFInfo
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- CN112584947A CN112584947A CN201980052761.2A CN201980052761A CN112584947A CN 112584947 A CN112584947 A CN 112584947A CN 201980052761 A CN201980052761 A CN 201980052761A CN 112584947 A CN112584947 A CN 112584947A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/106—Shielding the molten jet
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Abstract
A method for starting continuous casting of steel, wherein, in order to efficiently and easily reduce the oxygen concentration in the atmosphere in a tundish before the molten steel is poured, when the molten steel is poured into the tundish, the molten steel is poured in a state in which the oxygen concentration in the atmosphere in the tundish before the pouring is reduced by the replacement of the gas in the atmosphere in the tundish, and continuous casting is started, at this time, one or more gas discharge holes for replacing the atmosphere in the tundish are provided in addition to a molten steel pouring hole from a ladle in a lid of the tundish, the molten steel pouring hole and the gas discharge hole are arranged so that the distance therebetween satisfies a predetermined relationship with the length of the long side of the tundish, and the inert gas for replacing the atmosphere is supplied so as to satisfy a predetermined flow rate with respect to the tundish volume V.
Description
Technical Field
The present invention relates to a method for starting continuous casting of steel, and more particularly to a method for starting continuous casting by appropriately replacing an atmosphere in a tundish before starting pouring into a mold.
Background
In recent years, the quality and properties of steel materials are required to be improved year by year, and a technique for producing steel having higher cleanliness is required. In particular, non-metallic inclusions (hereinafter, referred to as "inclusions") in steel materials have a great influence on quality and characteristics, and thus reduction thereof is required. The inclusions present in steel include sulfides, nitrides, and the like, but most of them are oxides generated in the deoxidation process in the steel making process.
Therefore, conventionally, various technical developments in secondary refining processes have been made in order to remove inclusions generated during deoxidation. As a result, even for materials requiring high cleanliness, such as bearing steel, materials having an oxygen level of about several ppm in steel can be stably produced.
On the other hand, although molten steel after secondary refining passes through a tundish for dispensing into a continuous casting mold, if air is present in the tundish before molten steel is poured, the poured molten steel reacts with oxygen in the air to form oxide-based inclusions, and therefore, although the inclusions in the steel are reduced at the time of secondary refining, there is a problem that the tundish is contaminated again.
In order to solve such a problem, patent document 1 proposes the following method: the interior of the tundish is purged with an inert gas, and the molten steel is started to be poured into the tundish when the oxygen concentration in the tundish reaches 1 vol% or less.
Documents of the prior art
Patent document
Patent document 1: japanese patent 3642284 (Japanese laid-open publication No. 2002-254148)
Disclosure of Invention
Problems to be solved by the invention
However, the above-described prior art has the following problems. In the technique disclosed in patent document 1, a specific method for reducing the oxygen concentration in the tundish to 1 vol% is not clear, and depending on the flow rate of the inert gas and the form of the tundish at that time, it takes a long time to reduce the oxygen concentration in the atmosphere, and there is a problem of poor operation efficiency.
The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a method for efficiently and easily reducing the oxygen concentration in the atmosphere in a tundish before molten steel is poured in a continuous casting process.
Means for solving the problems
The method of the present invention developed to solve the above problems is a method for starting continuous casting of steel, characterized in that,
when molten steel is poured into a tundish disposed between a ladle for holding molten steel and a continuous casting mold for molten steel, the molten steel is poured in a state where the oxygen concentration in the atmosphere in the tundish before the start of pouring is reduced by replacement of the atmosphere in the tundish, and continuous casting is started,
the cover of the tundish is provided with one or more gas discharge holes for replacing the atmosphere in the tundish in addition to the molten steel injection hole from the ladle, and the cover is arranged so that the distance L between the molten steel injection hole and the gas discharge hole satisfies the following expression (1), and the atmosphere replacement inert gas is supplied to the tundish space from one or more supply pipes provided around the molten steel injection hole at a flow rate Q so that the total area A of the gas discharge holes and the tundish internal volume V satisfy the following expression (2).
W/4≤L≤2W/3…(1)
2.0≤Q2/(A·V)…(2)
Wherein the content of the first and second substances,
w: the inside length (m) of the long side of the tundish,
L: the shortest distance (m) between the center of the hole for pouring molten steel and the center of the hole for discharging the atmosphere replacement gas,
Q: total blowing flow rate (Nm) per unit time of inert gas for atmosphere replacement3Per minute),
A: total area (m) of gas discharge holes2)、
V: internal volume of tundish (m)3)。
The above method of the present invention may be further embodied in the following more preferable embodiments: when the shortest distance from the center of the molten steel injection hole provided in the cover of the tundish to the center of the gas discharge hole of the atmosphere replacement gas is represented by L satisfying the range of the formula (1), the inert gas is blown from at least one upper position separately from the inert gas blown from the periphery of the molten steel injection hole along the molten steel injection hole of the cover of the tundish within the range of 2L/3 from the center of the molten steel injection hole, and the inert gas is blown at an angle of 10 to 80 DEG to the gas discharge hole.
Further, the above method of the present invention may be a more preferred embodiment as follows: when the oxygen concentration in the tundish atmosphere satisfies the following expression (3), the pouring of molten steel in the ladle into the tundish is started.
0.3×M/V≥(O2)…(3)
M: molten steel amount (ton) when the tundish is full
V: internal volume of tundish (m)3)
(O2): oxygen concentration in the tundish atmosphereDegree (volume%)
Effects of the invention
According to the method for starting continuous casting of steel of the present invention having the above-described configuration, contamination of molten steel due to reoxidation can be effectively prevented by appropriately controlling the position of the gas discharge holes for the atmosphere replacement gas provided in the lid of the tundish, the total area of the gas discharge holes, the blowing angle of the inert gas, and the like, and a method extremely effective particularly for continuous casting of highly clean steel can be provided.
Drawings
Fig. 1(a), (b), (c), and (d) are schematic diagrams showing examples of the form of the tundish.
Fig. 2 is a partial cross-sectional view of the tundish.
Fig. 3 is a schematic diagram of the tundish for explaining the inert gas blowing angle.
Detailed Description
The inventors examined a preferable method for preventing contamination of molten steel by reoxidation by performing a process before continuous casting, in which an inert gas as an atmosphere replacement gas is previously blown into the tundish 1, as a treatment before continuous casting, with respect to the tundish 1 having various forms (a) to (d) shown in fig. 1. Fig. 2 and 3 show the specification (I type) of the tundish used as a precondition of the experiment. In these various tundishes, gas sampling holes were provided, and the oxygen concentration in the atmosphere of the tundish was measured by a vibrating suction pump and a gas oxygen concentration meter using an electrochemical oxygen sensor. At the stage of this study, the inventors confirmed that: the replacement time for making the oxygen concentration in the atmosphere in the tundish 1 low varies depending on the presence or absence of the gas discharge holes 3 for the atmosphere replacement gas in the tundish 1, the size and the installation position thereof, the blowing angle of the inert gas for replacement, and the blowing flow rate. As the inert gas used for atmosphere replacement in the tundish, argon, nitrogen, or the like can be used.
In addition, a weir for controlling the flow of molten steel for promoting the floating of inclusions may be provided in the tundish 1, and particularly, in the case where the weir plate 6 is provided downward from the tundish cap 1t, it is preferable to provide a gap at least in part between the weir plate 6 and the tundish cap 1t so as to communicate the space in the tundish 1 before and after the weir plate 6 so that the flow of gas in the tundish 1 is not obstructed even when the amount of molten steel stored in the tundish 1 increases and the lower end of the weir plate 6 is immersed in the molten steel.
From experiments conducted by the inventors at this time, it has been found that simply blowing an inert gas for atmosphere replacement and, if a gas discharge hole for properly discharging the gas is not provided, the blown inert gas or the like stays in the tundish 1 and is finally discharged from the molten steel injection hole 2, and as a result, unexpected movement or staying of the gas occurs in the tundish 1, and the decrease in oxygen concentration is not performed, and the atmosphere replacement takes a long time.
In contrast, it is known that: if the gas discharge holes 3 for discharging the atmosphere replacement gas are provided at appropriate positions of the tundish cover 1t, that is, if one or more gas discharge holes 3 are provided at positions on the tundish cover 1t that satisfy the condition of the following formula (1), a stable flow is formed in a certain direction without stagnation of the gas flow from the position where the inert gas for atmosphere replacement is blown into the gas discharge holes 3, and the atmosphere in the tundish can be replaced with a low oxygen concentration in a short time.
W/4≤L≤2W/3…(1)
Wherein the content of the first and second substances,
w is the inside length (m) of the long side of the tundish,
L is the shortest distance (m) between the center of the molten steel injection hole and the center of the gas discharge hole of the atmosphere replacement gas.
The center of the molten steel injection hole and the center of the atmosphere replacement gas discharge hole are set to the positions of the centers of gravity in the horizontal plane shape of the opening of the tundish cover.
In the present invention, when the gas discharge holes 3 for the atmosphere replacement gas are provided at positions that do not satisfy the condition of the above formula (1), that is, when L < W/4, the inert gas blown for the atmosphere replacement does not reach the entire area of the tundish 1, and the flow of the short-circuit gas toward the gas discharge holes 3 increases. Therefore, L.gtoreq.W/4 is preferred. On the other hand, when L > 2W/3, the position of the gas discharge hole 3 for discharging the atmosphere replacement gas is on the tundish end portion side (outer side), and there is a possibility that an appropriate opening area cannot be secured, so L is preferably 2W/3 or less.
In the present invention, it is also effective to control the total blowing flow rate per unit time of the atmosphere replacement inert gas blown into the tundish 1. That is, the blowing flow rate per unit time of the inert gas supplied into the tundish from one or more supply pipes provided around the molten steel pouring hole needs to satisfy the following expression (2). This is because, when replacing the atmosphere in the tundish before casting, particularly when replacing the ladle during continuous casting, it is necessary to efficiently replace the gas for a limited period of time. That is, in order to replace the atmosphere from the atmospheric atmosphere to the low oxygen concentration in a short time, particularly within about several minutes, it is necessary to supply the flow rate of the inert gas per unit time satisfying the following expression (2) with respect to the area of the gas discharge hole and the volume of the inside of the tundish. If the condition of the formula (2) is not satisfied, Q is changed2If (a · V) < 2.0, the flow rate of the inert gas used for the atmosphere replacement is insufficient for the total area of the gas discharge holes and the internal volume of the tundish, and the outflow rate of the inert gas at the gas discharge holes cannot be secured, so that the influence of the inflow of the air becomes large, and the atmosphere replacement cannot be performed efficiently.
2.0≤Q2/(A·V)…(2)
Wherein the content of the first and second substances,
q is a total blowing flow rate (Nm) per unit time of the inert gas for atmosphere replacement3Per minute),
A is the total area (m) of the gas discharge holes2)、
V is the internal volume (m) of the tundish3)。
Note that, Nm3N of (a) represents a standard state of the gas.
The reason why the total blowing flow rate of the inert gas for atmosphere replacement is limited is that Q needs to be satisfied in order to achieve sufficient atmosphere replacement2/(. A.V) ≧ 2.0, Q is preferably2/(A.V) ≧ 6.0, for this reason, it is effective to install at an appropriate position one or more inert gas blowing pipes 4 described later.
Note that, as long as the gas discharge hole 3 of the inert gas for atmosphere replacement satisfies the above expression (1), not only the tundish cover 1t but also the overflow vessel opening 5 (fig. 1(d)) used in an emergency may be used instead. In this case, L represents the distance between the molten steel inlet hole 2 and the overflow vessel opening 5. In addition, in an actual tundish, there may be a gap between the lid and the lid or between the lid and the tundish shell or the like, and therefore, an inert gas introduced into or blown into the tundish flows out through the gap and an appropriate gas flow cannot be formed, and therefore, the effect of the present invention may not be sufficiently obtained. Therefore, it is preferable to perform curing using a heat-resistant sheet or an unshaped refractory before casting. In the case where the overflow vessel opening 5 is not used as a discharge hole, it is preferable to perform maintenance using a heat-resistant sheet or the like to such an extent that the flow of molten steel is not obstructed in an emergency.
Next, the inventors have also studied the blowing manner of the inert gas into the tundish 1, particularly the blowing angle (θ) of one or more inert gas blowing pipes 4 provided separately from the blowing of the inert gas along the molten steel pouring hole 2. As a result, for example, in the example shown in fig. 2, by providing a predetermined inclination from at least one position toward the gas discharge hole 3 of the atmosphere gas (inert gas), the oxygen concentration in the atmosphere can be more effectively reduced. Here, as shown in fig. 3, the blowing angle θ of the inert gas is a downward angle toward the gas discharge hole 3 with reference to a straight line a-b in a plane passing through the inert gas blowing point a and the center b of the gas discharge hole 3 in the vertical direction. Basically, the inert gas is blown downward, but by inclining a part thereof by 10 to 80 ° toward the gas discharge hole 3, a propulsive force is given to the flow of the gas in the tundish 1, and the atmosphere can be adjusted (replaced with the gas) more efficiently.
The reason why the blowing angle of the inert gas blown from the blowing pipe 4 is inclined by 10 to 80 ° at this time is that, when the blowing angle is less than the inclination (θ) of 10 °, the blown gas flows along the lid of the tundish 1 and does not effectively function. On the other hand, if the blowing angle is larger than 80 °, the air flows almost directly downward, and therefore, this is not effective from the viewpoint of imparting propulsive force. In addition, the angle of inclination is preferably set to be less than 80 ° because the blowing position rather acts to block the flow of inert gas blown from around the molten steel pouring hole 2.
When the shortest distance between the center of the molten steel inlet hole 2 of the tundish cover 1t and the center of the gas discharge hole 3 of the atmosphere replacement gas is L, the position of the inert gas blowing pipe 4 to which the inclination is given is preferably set within a range of 2L/3 of the center of the molten steel inlet hole 2. If the installation position is more than 2L/3, the inert gas blown in from the periphery of the molten steel inlet hole 2 through the inert gas blowing pipe 4' is discharged from the gas discharge hole 3 before the propulsive force is applied to the inert gas, and therefore, the expected effect cannot be obtained.
Therefore, the inert gas is blown from at least one place or more through the inert gas blowing pipe 4 within a range of 2L/3 from the center of the molten steel pouring hole 2 of the tundish cover 1t, separately from the inert gas blown from the periphery of the molten steel pouring hole 2. Further, the effect of the present invention can be obtained only if the horizontal component of the inert gas blown into the pipe is within 20 ° to the left and right of the line ab.
In the above description, the opening area of the gas discharge holes 3 for the atmosphere replacement gas provided in the tundish cover 1t is not particularly limited, but the opening area of the gas discharge holes 3 is made larger than pi (H/4)2In the case of (2), the influence of the inflow of the atmosphere increases. Therefore, in order to more efficiently carry out the present invention, it is preferable that the opening area of the gas discharge hole 3 is pi (H/4)2The following. Here, H is the inner length (m) of the tundish short side. At this time, the heat exchanger is installed in the tundish 1When the overflow vessel for emergency use in (3) is used as one of the gas discharge holes, it is only necessary that the opening area is pi (H/4)2The same effects can be obtained as follows.
Further, as a result of various experiments and studies, it was found that the amount of reoxidation of molten steel is affected by the oxygen concentration in the tundish, the weight of molten steel in the tundish at the time of full charge, and the volume in the tundish. That is, when the oxygen concentration in the tundish at the time of starting the pouring of the molten steel in the ladle into the tundish satisfies the following expression (3), the increase in oxygen in the molten steel due to reoxidation can be greatly reduced, and the increase in oxygen concentration in the molten steel can be made less than 1 mass ppm. On the other hand, if expression (3) is not satisfied, the influence of the oxygen concentration in the tundish atmosphere on the molten steel may increase, and inclusions caused by reoxidation may increase.
Therefore, it is preferable to start pouring molten steel from a ladle to a tundish at a time when the oxygen concentration in the tundish atmosphere satisfies expression (3).
0.3×M/V≥(O2)…(3)
M: molten steel amount (ton) when the tundish is full
V: internal volume of tundish (m)3)
(O2): oxygen concentration in tundish atmosphere (% by volume)
Here, "full" means that the amount of molten steel contained in the tundish is the largest during steady pouring in the continuous casting machine.
Further, as a result of various experiments and studies, it was found that the amount of reoxidation of molten steel is affected by the oxygen concentration in the tundish, the weight of molten steel in the tundish at the time of full charge, and the volume in the tundish. That is, when the oxygen concentration in the tundish at the time of starting the pouring of the molten steel in the ladle into the tundish satisfies the following expression (3), the increase in oxygen in the molten steel due to reoxidation can be greatly reduced, and the increase in oxygen concentration in the molten steel can be made less than 1 mass ppm. On the other hand, if expression (3) is not satisfied, the influence of the oxygen concentration in the tundish atmosphere on the molten steel may increase, and inclusions caused by reoxidation may increase.
Therefore, it is preferable to start pouring molten steel from a ladle to a tundish at a time when the oxygen concentration in the tundish atmosphere satisfies expression (3).
0.3×M/V≥(O2)…(3)
M: molten steel amount (ton) when the tundish is full
V: internal volume of tundish (m)3)
(O2): oxygen concentration in tundish atmosphere (% by volume)
Example 1
Hereinafter, examples of the present invention will be described in comparison with comparative examples. This example is an example of manufacturing bearing steel, which is a representative example of high-cleanliness steel, through the steps of converter, ladle refining furnace, RH vacuum degassing furnace, and continuous casting using a full-scale machine in which the amount of molten steel charged at one time is about 200 tons. The bearing steel comprises the following components: the carbon concentration is 0.90 to 1.10 mass%, the silicon concentration is 0.15 to 0.25 mass%, the manganese concentration is 0.45 mass% or less, the phosphorus concentration is 0.020 mass% or less, the sulfur concentration is 0.0050 mass% or less, the aluminum concentration is 0.030 mass% or less, the chromium concentration is 1.4 to 1.7 mass% or less, and the nitrogen concentration is 0.0050 mass% or less. In each method, a square ingot (having a cross-sectional dimension perpendicular to the ingot drawing direction of 300mm in thickness × 400mm in width) was cast from a ladle through a tundish through a heating stirring treatment and an RH vacuum degassing treatment in a ladle refining furnace at an ingot drawing speed of about 0.70 m/min by a bending type continuous casting machine (having no vertical portion directly below the mold). At this time, various types of tundishes (T-type in fig. 1(a) and I-type in fig. 1(b), (c), and (d)) were used, and first, the interior of the vessel was heated to about 1000 ℃ by flames generated by burning coke oven gas using burners provided at heating positions of the casting bed. Then, the burner is turned off, the tundish is moved to the pouring position, and the inert gas is blown into the tundish through a gas blowing pipe provided separately from the supply pipe of the molten steel injection hole. Then, the molten steel in the ladle is poured into the tundish through a long nozzle attached to a slide nozzle on the bottom surface of the ladle. Further, an index of the total oxygen concentration in the cast slab, in which the sum of the total oxygen concentration in the molten steel before pouring into the tundish, that is, the dissolved oxygen concentration, and the oxygen concentration corresponding to inclusions is 1, is also shown. The total oxygen analysis sample was cut from a position of a thickness 1/4 at the center of the width in the top cross section of the bottommost portion of the cast piece cut at a position reaching about 3 tons from the casting start end, and subjected to analysis by the inert gas melting-infrared absorption method.
Table 1 shows the form of the tundish, the total flow rate of the inert gas, and the oxygen concentration in the tundish atmosphere 3 minutes after the start of the inert gas injection, for the inventive examples and the comparative examples.
As shown in Table 1, the inventive examples all have the following results: the oxygen concentration in the atmosphere in the tundish at the time of starting the injection into the tundish was reduced to 2% by volume or less, and reached a level at which re-oxidation hardly occurred even after the molten steel injection, and the total oxygen concentration in the cast slab was good. On the other hand, as a result of the test using the tundish provided with no gas discharge hole for atmosphere replacement gas, the oxygen concentration at the time of starting the molten steel injection into the tundish was as high as 2.9 vol% to 6.2 vol%. Even when the gas discharge hole is used, if the distance between the molten steel injection hole and the gas discharge hole of the inert gas is shorter than the conditions of the present invention, or if the total flow rate of inert gas blown into the tundish is insufficient relative to the intermediate volume and the area of the gas discharge hole, the oxygen concentration at the time of starting molten steel injection into the tundish is 3 vol% or more, and the level of inhibiting reoxidation of molten steel is not reached. As a result, the total oxygen concentration in the cast piece was increased as compared to before the injection into the tundish, and no good results were obtained.
Example 2
Bearing steel having the same composition as in example 1 was produced in the steps of converter, ladle refining furnace, RH vacuum degassing furnace and continuous casting using a commercial machine having a molten steel amount of about 200 tons in one charge in the same manner as in example 1. At this time, molten steel injection into the tundish is started by using various forms of tundish defined by L and W.
Table 2 shows the form of the tundish, the weight of molten steel when the tundish is full, the total flow rate of inert gas blown into the tundish, and the oxygen concentration in the tundish atmosphere at the time of starting the molten steel injection into the tundish, according to the example of the present invention. Further, an index of the total oxygen concentration in the cast slab, in which the sum of the total oxygen concentration in the molten steel before pouring into the tundish, that is, the dissolved oxygen concentration, and the oxygen concentration corresponding to inclusions is 1, is also shown. The cutting position and the analysis method of the cast piece sample for the total oxygen concentration were the same as in example 1.
As shown in Table 2, the following results were obtained in all the inventive examples: the oxygen concentration in the atmosphere in the tundish at the start of molten steel injection into the tundish was reduced to 2% by volume or less, and the total oxygen concentration in the cast slab was also good. In the examples 15 to 18 of the present invention in which the gas discharge holes for the inert gas were appropriately provided and the inert gas was blown in at an angle, the oxygen concentration in the tundish atmosphere at the time of starting the pouring of the molten steel into the tundish could be more stably reduced than in the case where the inert gas was not blown in at an angle. In addition to the oblique blowing, the oxygen concentration in the tundish atmosphere at the time of starting the molten steel injection into the tundish was set to 0.3 XM/V (M: weight (ton) of molten steel when the tundish was full and V: volume (M) in the tundish3) Inventive examples 19 to 22 below, the oxygen concentration in the atmosphere in the tundish was reduced to 1% by volume or less, and very good results of about 7 or less before injection into the tundish were obtained with respect to the total oxygen concentration in the cast slab.
Industrial applicability
The effects of the present invention are not limited by the components and concentrations of the steel, and can be applied to steels of all component systems.
Description of the symbols
1 tundish
1t tundish cover
2 molten steel injection hole
3 holes for gas discharge
4 inert gas blowing pipe
5 overflow trough opening part
6 weir
Claims (3)
1. A method of starting continuous casting of steel, characterized in that,
when molten steel is poured into a tundish disposed between a ladle for holding molten steel and a continuous casting mold for molten steel, the molten steel is poured in a state where the oxygen concentration in the atmosphere in the tundish before the start of pouring is reduced by replacement of the atmosphere in the tundish, and continuous casting is started,
the cover of the tundish is provided with one or more gas discharge holes for replacing the atmosphere in the tundish in addition to the molten steel injection hole from the ladle, and is arranged so that the distance L between the molten steel injection hole and the gas discharge hole satisfies the following expression (1), and an atmosphere replacement inert gas is supplied into the tundish space from one or more supply pipes provided around the molten steel injection hole at a flow rate Q so that the total area A of the gas discharge holes and the tundish internal volume V satisfy the following expression (2),
W/4≤L≤2W/3…(1)
2.0≤Q2/(A·V)…(2)
wherein the content of the first and second substances,
w: the inside length (m) of the long side of the tundish,
L: the shortest distance (m) between the center of the hole for pouring molten steel and the center of the hole for discharging the atmosphere replacement gas,
Q: total blowing flow rate (Nm) per unit time of inert gas for atmosphere replacement3Per minute),
A: total area (m) of gas discharge holes2)、
V: internal volume of tundish (m)3)。
2. The method of starting continuous casting of steel according to claim 1, wherein when a shortest distance from a center of the molten steel injection hole provided in the lid of the tundish to a center of a gas discharge hole of the atmosphere replacement gas is represented by L satisfying a range of the formula (1), the inert gas is blown from at least one upper position separately from the inert gas blown from around the molten steel injection hole along the molten steel injection hole of the lid of the tundish within a range of 2L/3 or less from the center of the molten steel injection hole provided in the lid of the tundish, and the inert gas is blown at an angle of 10 to 80 ° toward the gas discharge hole.
3. The method of starting continuous casting of steel according to claim 1 or 2, wherein the pouring of the molten steel in the ladle into the tundish is started after a time at which the oxygen concentration in the atmosphere of the tundish satisfies the following formula (3),
0.3×M/V≥(O2)…(3)
m: the quantity of molten steel is one ton when the tundish is full,
V: internal volume of tundish (m)3)、
(O2): oxygen concentration in the tundish atmosphere (% by volume).
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| PCT/JP2019/033828 WO2020045544A1 (en) | 2018-08-31 | 2019-08-29 | Method for starting continuous casting of steel |
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| CN103949628A (en) * | 2014-04-30 | 2014-07-30 | 北京科技大学 | Device and method for eradicating secondary oxidation of tundish during continuous casting |
| CN104364032A (en) * | 2012-06-18 | 2015-02-18 | 杰富意钢铁株式会社 | Method for manufacturing high-purity steel casting, and tundish |
| CN207479546U (en) * | 2017-11-06 | 2018-06-12 | 江阴兴澄特种钢铁有限公司 | A kind of airway applied to continuous casting production blowing argon |
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| JP3394612B2 (en) * | 1994-12-02 | 2003-04-07 | 川崎製鉄株式会社 | Non-oxidizing heat retention method for tundish |
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| JPH04300058A (en) * | 1991-03-28 | 1992-10-23 | Nippon Furnace Kogyo Kaisha Ltd | Inert gas supply device for tandish |
| CN1140490A (en) * | 1994-12-02 | 1997-01-15 | 川崎制铁株式会社 | Non-oxidizing heating method and apparatus therefor |
| JP2002254148A (en) * | 2001-02-28 | 2002-09-10 | Kawasaki Steel Corp | Method for preventing contamination of molten steel in tundish |
| CN104364032A (en) * | 2012-06-18 | 2015-02-18 | 杰富意钢铁株式会社 | Method for manufacturing high-purity steel casting, and tundish |
| CN103949628A (en) * | 2014-04-30 | 2014-07-30 | 北京科技大学 | Device and method for eradicating secondary oxidation of tundish during continuous casting |
| CN207479546U (en) * | 2017-11-06 | 2018-06-12 | 江阴兴澄特种钢铁有限公司 | A kind of airway applied to continuous casting production blowing argon |
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| Publication number | Publication date |
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| JP6841386B2 (en) | 2021-03-10 |
| WO2020045544A1 (en) | 2020-03-05 |
| CN112584947B (en) | 2022-01-11 |
| JPWO2020045544A1 (en) | 2021-03-11 |
| BR112021001763A2 (en) | 2021-04-27 |
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