JP6102501B2 - High Cr steel continuous casting method - Google Patents

Description

  The present invention relates to a continuous casting method of high Cr steel, and more particularly to a continuous casting method that enables continuous casting of a slab having a circular cross section with good surface properties.

  Seamless steel pipes (hereinafter simply referred to as “steel pipes”) used for oil well pipes and line pipes for transporting oil or natural gas are manufactured by the Eugene pipe manufacturing method, the Mannesmann pipe manufacturing method, or the like. Specifically, by these pipe making methods, a slab having a circular cross section (hereinafter also referred to as “round slab”) is processed into a hollow raw tube, and then the raw tube is drawn and heat-treated. Or manufactured.

  Round slabs that can be used in these pipe making methods include those obtained by split-rolling continuous cast slabs with a rectangular cross section (hereinafter referred to as “rectangular slabs”), or crossing the inner wall surface. Examples thereof include those that are continuously cast using a mold having a circular surface (hereinafter referred to as “circular cross-section mold”).

  In the case of using a rectangular slab, partial rolling is necessary, and thus unsteady portions are formed at both ends of the obtained round slab. The unsteady part needs to be cut as a crop, which contributes to the deterioration of the manufacturing cost of the round cast slab.

  In contrast, a round slab continuously cast using a circular cross-section mold can be manufactured at a lower cost than a round slab obtained by split rolling. Therefore, it is desirable that this inexpensive round slab can be used as it is continuously cast and a steel pipe can be produced without the occurrence of defective parts.

  However, round slabs continuously cast using a circular cross-section mold tend to have poor surface properties as compared to round slabs obtained by split rolling.

  When the inner surface has a rectangular cross section (hereinafter referred to as a “rectangular cross section mold”), the solidified shell formed on the slab has a rectangular cross section. Bulging is more likely to occur than when it is circular. Therefore, even if the solidified shell is deformed due to solidification shrinkage and the mold and the solidified shell are separated, the slab is bulged by the molten steel static pressure, and the mold and the solidified shell are immediately brought into close contact with each other. Due to the ease of bulging, there is no part of the slab where cooling is delayed, and a slab having a good surface property can be obtained as compared with the case of using a circular cross-section mold.

  The reason why the surface properties of round cast pieces continuously cast using a circular cross-section mold are likely to be poor is that the solid cross-section of the solidified shell formed on the cast pieces is circular, and bulging is unlikely to occur. If the slab does not bulge, the mold and the solidified shell are likely to be separated from each other, and cooling is delayed at a portion where the slab is separated from the mold. In parts where cooling is delayed, vertical cracks, depletion, and rashes tend to occur, and surface properties tend to be poor.

  Further, in the case of high Cr steel having a high Cr content in molten steel, the use of a circular cross-section mold tends to cause poorer surface properties. This is because the higher the Cr content of steel, the higher the high-temperature strength, and thus the solidified shell deformed by solidification shrinkage becomes more difficult to bulge.

  Furthermore, in the case of high Cr steel having a high Ni content in the molten steel, the surface properties are more likely to be poor. This is due to the fact that the higher the Ni content, the easier the austenite phase to crystallize as primary crystals or during the solidification process. Since the austenite phase has a higher density than the ferrite phase, when the austenite phase is crystallized, the solidification shrinkage is larger than when the ferrite phase is crystallized, and the mold and the solidified shell are easily separated.

  Longitudinal cracks, depletions, and rashes are generated starting from the detachment between the mold and the solidified shell accompanying the shrinkage of the solidified shell in the initial stage of solidification. Therefore, in order to suppress the occurrence of these surface defects, it is important to suppress the separation between the mold and the solidified shell in the initial stage of solidification.

  In general, when a circular cross-section mold is used, it is difficult to bulge the molten steel once solidified, and it is difficult to bring the mold and the solidified shell into close contact with each other. However, when the molten steel is solidified while being pressed against the mold at the solidification start point near the meniscus, the separation between the mold and the solidified shell due to the solidification shrinkage of the solidified shell is suppressed, and the mold and the solidified shell are easily brought into close contact with each other. .

  As a method for bringing the mold and the solidified shell into close contact with each other, Patent Document 1 discloses a method of pressing the solidified shell at the initial stage of solidification against a mold with a roller installed in molten steel in the mold. However, in this method, when the roller support rod passes through the molten steel and the mold flux at the top of the molten steel, the mold flux is caught in the vortex generated at the rear of the support rod, resulting in an internal defect of the slab. In addition, there is a possibility that problems such as difficulty in operation due to heat removal from the molten steel by the support rod and skinning of the molten steel surface.

  Conventionally, electromagnetic stirring that stirs molten steel in a mold by electromagnetic force has been applied to continuous casting. Patent Document 2 describes the formation of defects in the slab surface, Patent Document 3 forms a white band (negative segregation band on the billet surface layer), Patent Document 4 describes formation of macro-segregation and internal defects, respectively. It is disclosed to suppress by stirring. However, it has not been studied so far to bring the mold and the solidified shell into close contact by electromagnetic stirring.

Japanese Patent Laid-Open No. 3-8536 JP-A-1-180762 Japanese Patent Laid-Open No. 2001-25848 Japanese Patent Laid-Open No. 60-44157

  As described above, when the Cr content of steel is high, there is a problem that due to high strength at high temperatures, the mold and the solidified shell are likely to be separated due to solidification shrinkage, and the surface properties are likely to be poor. In the method disclosed in Patent Document 1, although the mold and the solidified shell can be brought into close contact with each other, there is a problem that the internal quality of the obtained slab is low and continuous casting operation may be difficult.

  The present invention has been made in view of these problems. Even if the Cr content of steel is high, it is possible to easily produce a round slab having good internal quality and good surface properties. An object is to provide a casting method.

  As a method for bringing the mold and the solidified shell into close contact with each other, the present inventors focused attention on the centrifugal force generated by rotating and flowing molten steel in the horizontal direction, and repeated studies. This is because by generating a centrifugal force in the molten steel, the molten steel can be solidified while being pressed against the mold at a solidification start location near the meniscus without providing a member such as a roller in the molten steel in the mold.

  And the range of the flow rate of the molten steel from which a round slab with favorable surface property is obtained when continuously casting a round slab from molten steel with a high Cr content (Cr content: 8 mass% or more and 30 mass% or less) It was found that there exists.

  This invention is made | formed based on this knowledge, The summary exists in the following continuous casting method of high Cr steel.

A continuous casting method of high Cr steel using a mold having a circular inner wall cross section and continuously casting a molten steel having a Cr content of 8% by mass or more and 30% by mass or less into a round cast slab, The maximum flow velocity u (mm / s) in the mold inner wall circumferential direction of the molten steel on the molten metal surface in the mold is set to the Cr content ratio X (mass) in the molten steel. %) In a range represented by the following formulas (1-1) and (1-2).
8 ≦ X <20: 50 ≦ u ≦ 570 (1-1)
20 ≦ X ≦ 30: 20X−350 ≦ u ≦ 570 (1-2)

  In the continuous casting method of high Cr steel of the present invention, the molten steel is rotationally flowed using an electromagnetic stirrer. At this time, the frequency (Hz) of the alternating current applied to the electromagnetic stirrer and the magnetomotive force (AT , Ampere-turn) is preferably 18900 Hz AT or more and 252000 Hz AT or less. The magnetomotive force is the product of the effective value (A) of the alternating current and the number of turns of the coil of the electromagnetic stirrer.

  Moreover, in the continuous casting method of the high Cr steel of the present invention, the molten steel of the high Cr steel contains Ni, and the ratio value (Cr / Ni) of the Cr content (mass%) of the molten steel to the Ni content (mass%). ) Is 2.5 or less, the improvement in the surface property of the slab is large by setting the flow rate of the molten steel within the range defined by the above formulas (1-1) and (1-2).

  In the following description, “mass%” for the component composition of steel is also simply expressed as “%”.

  According to the continuous casting method of high Cr steel of the present invention, it is possible to produce a round slab having a good surface property even when the Cr content of the steel is high. Moreover, since it is not necessary to provide members, such as a roller, in the molten steel in a casting_mold | template, a continuous casting operation can be performed simply.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the linear induction motor type electromagnetic stirring apparatus applicable to the continuous casting method of the high Cr steel of this invention, The figure (a) is the front view shown with the casting_mold | template, The figure (b) is the figure (a) It is sectional drawing by the bb line | wire of (). It is a figure which shows the relationship between the Cr content rate of molten steel, the maximum flow velocity of the circumferential direction of molten steel, and the surface property as a test result of an Example. It is a figure which shows the relationship between the product of the frequency of an alternating current, and a magnetomotive force, and the maximum flow velocity of the circumferential direction of molten steel.

1. Continuous casting method of high Cr steel of the present invention In the continuous casting method of high Cr steel of the present invention, a mold having a circular inner wall cross section is used, and the Cr content of molten steel used for casting is 8% or more and 30%. The following.

In addition, the molten steel in the mold is rotated and flowed in the horizontal direction. At that time, the maximum flow velocity u (mm / s) in the circumferential direction of the inner wall surface of the molten steel on the molten metal surface in the mold is set to the Cr content X (mass) %) In the range represented by the following formulas (1-1) and (1-2). Thereby, a casting_mold | template and a solidified shell can be closely_contact | adhered with the centrifugal force which generate | occur | produces in molten steel, and a slab with favorable surface property is obtained.
8 ≦ X <20: 50 ≦ u ≦ 570 (1-1)
20 ≦ X ≦ 30: 20X−350 ≦ u ≦ 570 (1-2)

  When the maximum flow velocity in the circumferential direction of the molten steel is smaller than the lower limit of the range expressed by the above formulas (1-1) and (1-2), the centrifugal force is not sufficiently generated in the molten steel. Therefore, the force for pressing the molten steel against the mold at the solidification start position near the meniscus in the mold becomes insufficient, the mold and the solidified shell cannot be brought into close contact with each other, and the mold and the solidified shell are easily separated.

  On the other hand, when the maximum flow velocity in the circumferential direction of the molten steel is larger than the upper limit of the range represented by the above formulas (1-1) and (1-2), the centrifugal force generated in the molten steel becomes excessive. When excessive centrifugal force is generated in the molten steel in the mold, the molten steel surface is low in the vicinity of the immersion nozzle and high in the vicinity of the inner wall of the mold, and the difference in height between the two becomes significant. Along with this, the thickness of the mold flux on the molten steel surface becomes thinner as it approaches the inner wall of the mold. Therefore, it is difficult for the mold flux to flow between the mold and the solidified shell, and poor lubrication tends to occur between the mold and the solidified shell.

The maximum flow velocity u (mm / s) in the circumferential direction of the inner wall surface of the molten steel on the molten metal surface in the mold and the Cr content X (mass%) of the molten steel are the following formula (2-1) or formula (2-2): It is desirable to satisfy this relationship.
8 ≦ X <20: 90 ≦ u ≦ 570 (2-1)
20 ≦ X ≦ 30: 22X−350 ≦ u ≦ 570 (2-2)

  The casting speed is 0.3 m / min or more and 2.0 m / min or less. If the casting speed is less than 0.3 m / min, the solidified shell becomes too thick as a whole, and the effect of bringing the mold and the solidified shell into close contact with each other due to the centrifugal force generated in the molten steel cannot be obtained. On the other hand, when the casting speed is higher than 2.0 m / min, the solidified shell becomes too thin, which promotes non-uniform growth of the solidified shell.

  The immersion nozzle disposed in the mold is a so-called single-hole straight nozzle in which only one ejection hole is disposed on the bottom surface of the nozzle, but two or more ejection holes are disposed on the side surface of the nozzle. May be. Anyway, the shape which discharges molten steel is desirable so that the flow of the circumferential direction of molten steel may not be inhibited.

  Ni may be contained in the molten steel having the Cr content of 8% or more and 30% or less. In the molten steel containing Ni, when the ratio value (Cr / Ni) of the Cr content (mass%) to the Ni content (mass%) is 2.5 or less, the flow rate of the molten steel (1- The range of improvement in the surface properties of the slab by being within the range defined by the formulas (1) and (1-2) is large.

  When Cr / Ni is 2.5 or less, the austenite phase is mainly crystallized as primary crystals or in the solidification process. Tends to deviate. This is because the austenite phase has a higher density than the ferrite phase, so that the higher the ratio of the austenite phase to the ferrite phase, the greater the solidification shrinkage.

  However, according to the present invention, even when Cr / Ni is 2.5 or less, the mold and the solidified shell can be brought into close contact with the centrifugal force generated in the molten steel, as in the case where it is larger than 2.5. As a result, a slab having good surface properties can be obtained. Therefore, when Cr / Ni is 2.5 or less, there is a large improvement in the surface property of the slab by setting the flow rate of the molten steel within the specified range of the present invention. This improvement width becomes larger when Cr / Ni is 1.5 or less.

  The mold flux disposed on the molten steel surface in the mold preferably has a freezing point of 1100 ° C. or higher and 1280 ° C. or lower. When the freezing point is lower than 1100 ° C., the crystallization of the mold flux flowing between the mold and the solidified shell is delayed, which may promote the nonuniform growth of the solidified shell. On the other hand, when the freezing point is higher than 1280 ° C., the crystallization of the mold flux flowing between the mold and the solidified shell becomes faster and the mold flux may not flow sufficiently. The freezing point of the mold flux is more preferably 1120 ° C. or higher and 1250 ° C. or lower.

  Moreover, as for mold flux, it is desirable for the viscosity in 1300 degreeC to be 2 poise or more and 8 poise or less. If this viscosity is less than 2 poise, mold flux may flow excessively, and if it is higher than 8 poise, it may not be able to flow sufficiently. The viscosity of the mold flux at 1300 ° C. is more preferably 3 poise or more and 7 poise or less.

2. Method of rotating and flowing molten steel As a method of rotating and flowing molten steel in a mold in a horizontal direction, a method using an immersion nozzle provided with discharge holes so as to form a swirling flow in the circumferential direction of the inner surface of the mold, or the mold itself is rotated. And a method of applying electromagnetic force to molten steel. Among these methods, the electromagnetic stirring method that is widely used at present and stirs by applying electromagnetic force to molten steel is suitable. However, any method may be used as long as the molten steel in the mold can be rotationally flowed at the prescribed flow rate to generate centrifugal force.

  A method of rotating and flowing the molten steel in the mold in the horizontal direction by an electromagnetic stirring method will be described by taking the technique disclosed in Patent Document 4 as an example.

  FIG. 1 is a configuration diagram of a linear induction motor type electromagnetic stirrer that can be applied to the continuous casting method of high Cr steel of the present invention. FIG. 1 (a) is a front view together with a mold, and FIG. It is sectional drawing by the bb line of the same figure (a). The electromagnetic stirring device 11 is arranged along the long side surface of the mold 3. The mold 3 shown in the figure is a rectangular cross-section mold, but the electromagnetic stirrer 11 can also be applied to a circular cross-section mold.

  The electromagnetic stirring device 11 is a linear induction motor type, and includes an iron core 21, a U-phase coil 46, a V-phase coil 47, and a W-phase coil 48. The iron core 21 includes slots 37, 38 and 39 at the center and both ends in the longitudinal direction. A magnetic pole 50 is formed between the slot 37 and the slot 38, and a magnetic pole 51 is formed between the slot 37 and the slot 39.

  The slot 37 and the slot 38 accommodate the U-phase coil 46 so as to surround the magnetic pole 50, and the slot 37 and the slot 39 accommodate the V-phase coil 47 so as to surround the magnetic pole 51. Further, W-phase coil 48 is accommodated in slots 38 and 39 so as to surround U-phase coil 46 and V-phase coil 47.

  In the electromagnetic stirrer 11 configured as described above, an alternating current is supplied to the U-phase coil 46, the V-phase coil 47, and the W-phase coil 48 independently. The U-phase coil 46 and the V-phase coil 47 are energized so that the current phase is asymmetric with respect to the longitudinal center of the iron core 21. The W-phase coil 48 is energized with a phase shift of 2 / 3π so that the U-phase coil 46 adjacent to the slot 38 and the V-phase coil 47 adjacent to the slot 39 are opposite in phase. To do.

  By energizing in this way, the molten steel A in the mold 3 can be rotated and flowed in the direction of the arrow B, that is, in the circumferential direction of the inner wall surface of the mold 3.

  When rotating molten steel in a mold using an electromagnetic stirrer, the product of the frequency (Hz) of the alternating current applied to the electromagnetic stirrer and the magnetomotive force (AT, ampere turn) shall be 18900 Hz AT or more and 252000 Hz AT or less Is desirable. Thereby, the slab with favorable surface property can be obtained. The magnetomotive force is the product of the effective value (A) of the alternating current and the number of turns of the coil of the electromagnetic stirrer, and is generally a value used for evaluating the current value of the electromagnetic stirrer.

  When the present inventors conducted a continuous casting test of high Cr steel having a Cr content of 8% or more and 30% or less, the maximum flow velocity in the circumferential direction of the inner wall surface of the molten steel on the molten metal surface in the mold was 250 mm / s. As described above, it has been found that a slab having a better surface property can be obtained when it is 570 mm / s or less. Furthermore, as a result of examining the relationship between the flow rate of the molten steel and the setting conditions of the electromagnetic stirrer, when the product of the frequency of the alternating current and the magnetomotive force is 18900 Hz AT or more and 252000 Hz AT or less, the maximum flow velocity in the circumferential direction of the molten steel is 250 mm. It was found that it was not less than / s and not more than 570 mm / s.

  In order to confirm the effect of the continuous casting method of the high Cr steel of the present invention, the following tests were conducted and the results were evaluated.

1. Test Method Using the electromagnetic stirrer shown in FIG. 1, round cast pieces were continuously cast while the molten steel in the circular cross-section mold was rotated and flowed in the horizontal direction. The number of turns of each coil of the electromagnetic stirring device was 84 turns. The steel types used were those having the chemical composition shown in Table 1. In any steel type, the Cr content satisfies the range defined by the present invention.

  Table 2 shows the test conditions including the steel type, the ratio of Cr content (% by mass) to the Ni content (% by mass) of molten steel (Cr / Ni), the frequency of the alternating current applied to the electromagnetic stirrer and the effective The current value, the diameter of the inner wall of the mold and the casting speed were shown. In addition, the maximum flow velocity in the circumferential direction of the inner wall surface of the molten steel on the molten steel surface (free surface position) in the molten steel evaluated by numerical analysis simulation is shown. Since the flow rate of the molten steel is difficult to measure, it was calculated using a numerical analysis simulation.

  Test number 1-3 is steel type A, test number 4-9 is steel type B, test number 10 is steel type C, test number 11-14 is steel type D, test number 15-23 is steel type E, test number 24-28 is steel type F molten steel was used.

Test numbers 1, 4, 11, 15, and 24 are comparative examples in which the molten steel was not flowed. In test numbers 16 and 25, the maximum flow velocity u (mm / s) in the circumferential direction of the molten steel is expressed by the following formulas (1-1) and (1-2) according to the Cr content X (mass%) of the molten steel. This is a comparative example that was smaller than the prescribed range. Test numbers 9 and 23 are comparative examples in which the maximum flow velocity in the circumferential direction of the molten steel was larger than the range defined by the following formulas (1-1) and (1-2).
8 ≦ X <20: 50 ≦ u ≦ 570 (1-1)
20 ≦ X ≦ 30: 20X−350 ≦ u ≦ 570 (1-2)

  Test numbers other than these are examples of the present invention that satisfy the specified conditions of the present invention.

2. Test results Table 2 shows the quality evaluation results of the obtained slabs as test results. Quality evaluation was performed by evaluation of surface properties, that is, evaluation of occurrence of vertical cracks, depletion and rashes. In the table, the evaluation is a four-level evaluation of excellent, good, impossible and impossible, and the meaning of each is as follows.
Excellent: No vertical cracks, depletions and rashes occurred, or the depletion occurred slightly to the extent that no grinder maintenance was required. Good: Mild and costly, although vertical cracks, depletions and rashes occurred. The merit was such that it could be removed by maintenance with a grinder within a certain range. Impossible: Severe vertical cracking, depletion and rash occurred, and even if removed by care with a grinder, there was no cost merit. : Severe vertical cracks, depletion and rashes occurred, making continuous casting operation difficult.

FIG. 2 is a graph showing the relationship between the Cr content of molten steel, the maximum flow velocity in the circumferential direction of the molten steel, and the surface properties as test results of the examples. In the figure, the four-stage evaluation of the quality of the slab shown in Table 2 is indicated by symbols (◎, ○, × and ■). ◎ means excellent, ○ means good, × means impossible, ■ means impossible. Further, in the same figure, the circumference of the molten steel defined by the present invention represented by the above formulas (1-1) and (1-2) and the following formulas (2-1) and (2-2) The boundaries of the range of maximum flow velocity in the direction are also shown.
8 ≦ X <20: 90 ≦ u ≦ 570 (2-1)
20 ≦ X ≦ 30: 22X−350 ≦ u ≦ 570 (2-2)

  It can be seen from FIG. 2 that when the Cr content of the molten steel and the maximum flow velocity in the circumferential direction of the molten steel satisfy the provisions of the present invention, a slab having a good surface property can be obtained with good or excellent evaluation. That is, according to the continuous casting method of the high Cr steel of the present invention, it is understood that the detachment between the mold and the solidified shell, which is likely to occur along with the solidification shrinkage due to the large high temperature strength, can be suppressed.

3. Consideration 1
FIG. 3 is a diagram showing the relationship between the product of the frequency of the alternating current and the magnetomotive force and the maximum flow velocity in the circumferential direction of the molten steel. The figure shows the relationship between the product of the frequency of the alternating current and the magnetomotive force and the maximum flow velocity in the circumferential direction of the molten steel for 15 conditions including the conditions shown in Table 2. In the quality evaluation results shown in Table 2, the evaluation was excellent when the maximum flow velocity in the mold circumferential direction of the molten steel was 310 mm / s or more and 560 mm / s or less. From this figure, it is understood that when the product of the frequency of the alternating current and the magnetomotive force is 18900 Hz AT or more and 252000 Hz AT or less, the maximum flow velocity in the mold circumferential direction of the molten steel is within this range, and a slab having good surface properties can be obtained. .

4). Consideration 2
Test numbers 1, 4, 11, 15, and 24 are comparative examples in which the molten steel was not flowed. Of these, test numbers 1 and 4 could not be evaluated, while test numbers 11, 15 and 24 were even lower when evaluation was impossible. The biggest difference between test numbers 1 and 2 and test numbers 11, 15 and 24 is the ratio value (Cr / Ni) of the Ni content (mass%) to the Cr content (mass%) of the steel type used. is there.

  Steel type A used in Test No. 1 had Cr / Ni of 27.3, and Steel Type B used in Test No. 4 was 2.8, both of which were larger than 2.5. In contrast, the steel type D used in test number 11 was 2.2, the steel type E used in test number 15 and the steel type F used in test number 24 were 0.8 and 2.5 or less, respectively.

  As shown in Table 2, in the steel type with Cr / Ni larger than 2.5, the surface property of the obtained slab was only improved or not excellent in the present invention example from the impossibility of the comparative example. On the other hand, in the steel type with Cr / Ni of 2.5 or less, the quality of the example of the present invention was significantly improved from the impossible or impossible of the comparative example.

  That is, it can be said that the effect of the present invention is great in a steel type having Cr / Ni of 2.5 or less.

  According to the continuous casting method of high Cr steel of the present invention, it is possible to produce a round slab having a good surface property even when the Cr content of the steel is high. In addition, since there is no need to provide a roller or other member in the molten steel in the mold, there is no vortex generation of the molten steel and mold flux, and thus the manufactured round cast slab has good internal quality, and on the molten steel surface. Since there is no skinning, stable continuous casting operation is possible.

3: Mold, 11: Electromagnetic stirrer, 21: Iron core, 37, 38, 39: Slot,
46: U-phase coil, 47: V-phase coil, 48: W-phase coil, 50, 51: magnetic pole,
A: Molten steel, B: Flow direction of molten steel

Claims (3)

A continuous casting method of high Cr steel, using a casting mold whose inner wall has a circular cross section and continuously casting a molten steel having a Cr content of 8% by mass or more and 30% by mass or less to a round cast slab,
The molten steel is caused to rotate and flow in the horizontal direction in the mold, and at that time, the maximum flow velocity u (mm / s) in the circumferential direction of the inner wall surface of the molten steel on the molten metal surface in the mold is determined as the Cr content in the molten steel. According to X (mass%), it is set as the range represented by the following (1-1) type | formula and (1-2) type | formula, The continuous casting method of the high Cr steel characterized by the above-mentioned.
8 ≦ X <20: 50 ≦ u ≦ 570 (1-1)
20 ≦ X ≦ 30: 20X−350 ≦ u ≦ 570 (1-2)   The rotational flow of the molten steel is performed using an electromagnetic stirrer. At that time, the frequency (Hz) of the alternating current applied to the electromagnetic stirrer, the effective value (A) of the alternating current, and the electromagnetic stirrer 2. The continuous casting method for high Cr steel according to claim 1, wherein the product of the number of turns of the coil is 18900 Hz AT or more and 252000 Hz AT or less.   The molten steel contains Ni, and a value (Cr / Ni) of a Cr content (% by mass) to a Ni content (% by mass) of the molten steel is 2.5 or less. Or the continuous casting method of the high Cr steel of 2.

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