JP2013031867A - Casting mold for continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a casting mold for continuous casting that can prevent the inner corners of short sides positioned opposite each other between long sides positioned opposite each other from cracking and wearing.SOLUTION: The casting mold 10 for continuous casting includes the opposite long sides 11 and 12, and the opposite short sides 13 and 14 disposed between the long sides 11 and 12. In the device, the inner corners of the short sides 13 and 14 abutting on the interior surfaces of the long sides 11 and 12, or the inner corners which are the lower regions of the short sides 13 and 14 including meniscus parts and abutting on the long sides 11 and 12 are chamfered, and a space 19 is provided between the inner corners and the interior surfaces of the long sides 11 and 12, thus preventing the inner corners of the short sides 13 and 14 from getting damaged.

Description

The present invention relates to a continuous casting mold having long sides opposed to each other and short sides arranged opposite to each other so as to be laterally movable between the long sides.

Conventionally, in continuous casting using a continuous casting mold having a long side opposed to each other and a short side arranged so as to be laterally movable between the long sides, the solidification delay of the corner portion of the cast slab is made. In order to prevent quality abnormalities such as slab corner cracking due to corner solidification delay, the inner width of the long side facing the inner side of the long side corresponds to the solidification shrinkage shape of the slab. A continuous casting mold (multi-taper mold) in which a multi-taper is formed so as to narrow in the casting direction is used (see, for example, Patent Document 1). In the multitaper mold, the corner of the slab moves while always contacting the inner surface of the mold, which causes a problem of increased wear damage on the inner surface of the mold. A coating (for example, a thermal spray coating made of a Cr-Si-B alloy based on Ni) is formed to suppress wear on the inner surface of the mold.

Generally, in a continuous casting mold, the outer side is water-cooled during continuous casting and the inner side is heated by the injected molten steel, so that the thermal expansion of the inner surface of the short side is larger than the thermal expansion of the outer surface of the short side. And since the short side arranged oppositely is in a state of being pressed from both sides in the width direction of the short side by the long side arranged oppositely, thermal expansion in the width direction of the short side is restricted. A large strain (stress concentration) due to restraint is generated in a lower region including the meniscus portion in the inner corner portion. For this reason, in a multitaper mold in which a hard film is formed on the inner side of the short side, a high stress exceeding the strength of the hard film is applied to the inner corner (hard film) of the short side that contacts the inner surface of the long side. Occur. And since a hard film is inferior to ductility (plastic deformability), the problem that a chip | tip generate | occur | produces in a hard film (inner side of a short side) arises. Therefore, a chip having excellent ductility (plastic deformability) such as Ni plating is formed on the side end surface of the short side that is in contact with the inner surface of the long side, and the inner corner portion of the short side is plastically deformed. It is prevented from occurring.

JP 2008-49385 A

However, when a film having excellent ductility such as Ni plating is formed on the side edge of the short side, the film having excellent ductility is inferior in wear resistance, and therefore, wear damage occurs early on the inner corner of the short side. The problem arises. For this reason, there exists a problem that the lifetime of a multitaper mold becomes very short.

The present invention has been made in view of such circumstances, and provides a continuous casting mold capable of preventing chipping and abrasion of the inner corners of the short sides arranged oppositely between the long sides arranged opposite to each other. With the goal.

A continuous casting mold according to the present invention that meets the above-mentioned object is a continuous casting mold having a long side opposed to each other and a short side arranged oppositely between the long sides.
Chamfering the inner corner of the short side that contacts the inner surface of the long side, or the inner corner of the lower side that includes the meniscus portion of the short side and contacting the inner surface of the long side, A space was formed between the inner corner and the inner surface of the long side to prevent damage to the inner corner of the short side.

In the continuous casting mold according to the present invention, the chamfer dimension is 0.3 mm or more and 1 mm or less with respect to the width direction of the short side, and is 0.3 mm or more and 2 mm or less with respect to the thickness direction of the short side. be able to.

In the continuous casting mold according to the present invention, it is preferable that a wear-resistant reinforcing film made of a sprayed coating is formed on the inner corner portion of the short side where the chamfering is performed.

In the continuous casting mold according to the present invention, the sprayed coating may be a Ni- or Co-based Cr-Si-B alloy.
The thermal spray coating may be a composite material obtained by adding one or more of carbide, nitride, and boride to a Co, Ni, or Co—Ni alloy.

In the continuous casting mold according to the present invention, the inner corner of the short side, which is in contact with the inner surface of the long side, or the lower region including the meniscus portion of the short side, which is in contact with the inner surface of the long side Since chamfering was performed on the part, and a space was formed between the inner corner and the inner surface of the long side, the inner corner of the short side in the region where thermal expansion is remarkable inside the short side during continuous casting is It is possible to thermally expand to the inner surface side of the long side without being constrained, and to prevent distortion (stress concentration) associated with the constraining from occurring at the inner corner of the short side. As a result, it is possible to form a hard coating on the inner corner of the short side.

In the continuous casting mold according to the present invention, when the chamfering dimension is 0.3 mm or more and 1 mm or less with respect to the width direction of the short side and is 0.3 mm or more and 2 mm or less with respect to the thickness direction of the short side, It is possible to prevent the molten steel injected into the casting mold from entering the space. Thereby, a slab can be easily moved within a continuous casting mold.

In the continuous casting mold according to the present invention, when a wear-resistant reinforcing coating made of a thermal spray coating is formed on the inner corner of the short side to be chamfered, the inside of the short side due to contact with the slab Corner wear can be prevented.
And, when the thermal spray coating is made of a Cr-Si-B alloy based on Ni or Co, by performing the fusing treatment, the densification of the reinforcing coating and the bondability with the short side can be improved, The life of the reinforcing film can be extended.
Further, when the sprayed coating is made of a composite material in which any one or more of carbide, nitride, and boride is added to a Co, Ni, or Co—Ni alloy, scuffing occurs in the reinforcing coating. This can be prevented and the wear resistance can be further improved.

It is a perspective view of the continuous casting mold which concerns on one embodiment of this invention. It is sectional drawing of the long side of the same continuous casting mold. (A) is a partial side view of the short side of the continuous casting mold, and (B) is a view taken in the direction of arrows Q-Q of (A). It is a plane sectional view showing an inner corner part of a short side. In the continuous casting mold of an Example, it is a graph which shows the relationship between the fracture | rupture distortion rate which generate | occur | produces in the meniscus part of an inner side corner part of a short side at the time of continuous casting, and the chamfering dimension of the chamfer provided in an inner side corner part of a short side. In the continuous casting mold of an example, it is a graph which shows the relation between the crushing distortion rate which occurs in the position of 400mm below the meniscus of the short side inner corner at the time of continuous casting, and the chamfer dimension of the chamfer provided in the short side inner corner. is there.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIG. 1, a continuous casting mold 10 according to an embodiment of the present invention has long sides 11 and 12 that are opposed to each other, and a short side that is arranged so as to be laterally movable between the long sides 11 and 12. The slab forming part 15 which has the sides 13 and 14 and penetrated in the up-and-down direction (casting direction) is formed, and molten steel 16 (see FIG. 2) is supplied to the slab forming part 15 to cool the slab. (Not shown).

And the multitaper which the inner width of the opposing long sides 11 and 12 narrows toward the downward direction from which the slab is pulled out is formed inside the long sides 11 and 12. Further, in the short side lower portion 18 which is a lower side region including the meniscus portion of the short sides 13 and 14, the inner corner portion contacting the inner surface of the long sides 11 and 12 is chamfered, and the inner corner portion and A space portion 19 is formed between the inner surfaces of the long sides 11 and 12. Further, a wear-resistant reinforcing film 20 made of a sprayed coating is formed on the inner side of the long sides 11 and 12, and an inner surface and inner corners of at least the short side lower portion 18 of the short sides 13 and 14 are made of a sprayed coating. Abrasive reinforcing films 21 are formed respectively. Details will be described below.

A plurality of bolts (not shown) arranged in the vertical direction (casting direction) on the outer surfaces of the long sides 11 and 12 and the short sides 13 and 14 (the surface opposite to the surface in contact with the molten steel 16). A back plate (not shown) is attached via a fastening means group consisting of: Thereby, the cooling water is caused to flow from a water supply section (not shown) provided at the lower portion of the back plate to a large number of water guide grooves (not shown) provided on the outer surfaces of the long sides 11 and 12 and the short sides 13 and 14. Thus, the long sides 11 and 12 and the short sides 13 and 14 are cooled, and the molten steel 16 supplied to the slab forming portion 15 is cooled to produce a slab.

The short sides 13 and 14 have a thickness (thickness including the reinforcing coating 21) of, for example, about 5 mm to 100 mm, a width of about 50 mm to 300 mm, and a vertical length of about 600 mm to 1200 mm. is there. In addition, the long sides 11 and 12 have a thickness (thickness including the reinforcing film 20) of, for example, about 5 mm to 100 mm, and a distance between a pair of short sides 13 and 14 that are opposed to each other (a width in contact with the slab). ) In the range of 600 mm or more and 3000 mm or less, and the length in the vertical direction is approximately the same as the short sides 13 and 14. Thereby, for example, a slab having a width of about 600 mm to about 3000 mm and a thickness of about 50 mm to about 300 mm can be manufactured.

First, the multitaper configuration of the long side 11 shown in FIG. 1 (the same applies to the long side 12) will be described.
As shown in FIG. 2, on the inner surface of the long side 11, the molten steel surface position (meniscus position, sometimes simply referred to as the molten surface position) of the molten steel 16 is the upper position P1 across the width direction of the long side 11. A multitaper formed of a bulging portion 22 projecting toward the cast slab forming portion 15 is formed with a position 300 mm or more lower than the upper position P1 as a lower position P2. The molten steel surface position is within a range of 50 mm or more and 150 mm or less (here, about 100 mm) with the upper end position of the long side 11 as a base point. In addition, although the protrusion amount to the slab formation part 15 side of the bulging part 22 is slight, it has exaggerated in FIG. 1, FIG. 2 for convenience of explanation.

The reason why the upper position P1 of the bulging portion 22 is set as the molten metal surface position is that it is the starting position of the cooling of the molten steel 16. Further, the lower position P2 of the bulging portion 22 is set to a position of 300 mm or more downward from the upper position P1 between the solidified shell formed on the mold contact surface side of the molten steel 16 and the inner surface of the long side 11. This is because the range in which the gap is generated is within this range. From the above, the formation position of the bulging portion 22 is set to the upper position P1 from the molten metal surface position of the molten steel 16, and from the upper position P1 to the lower position P2 of 300 mm or more downward, the lower position P2 is the upper position. It is preferable that the position is at least 500 mm below P1 and further the lower end position of the short sides 13 and 14 and the long sides 11 and 12.

The inner surface contour line of the longitudinal section of the bulging portion 22 is composed of three or more and eight or less (three in the present embodiment) continuous linear portions L1 to L3 from the upper position P1 to the lower position P2. In addition, the inner surface of the long side 11 is composed of three or more inclined surfaces having different inclination angles. Here, when the number of straight portions constituting the bulging portion is less than three (two or less), the number of straight portions is too small, and the vertical cross-sectional shape of the bulging portion becomes an extreme shape that partially protrudes. The contact resistance with the slab increases, and wear damage is likely to occur at the bulge portion. On the other hand, when the number of straight portions exceeds eight (9 or more), the number of straight portions is too large, the processing of the bulging portion becomes complicated, and the manufacturing cost increases. From the above, the bulging portion 22 is composed of the three straight portions L1 to L3. However, the lower limit of the number of straight portions is preferably four, and the upper limit is preferably six.

For the straight line portions L1 to L3, the uppermost straight line portion L1, the angle θ1 formed by the second straight line portion L2 adjacent to the straight line portion L1, and the straight line portion L2 and the third straight line portion L3 from the top are formed. The angle θ2 is in the range of 174 degrees or more and 179.97 degrees or less, respectively. Note that the angles θ1 and θ2 are the same angle, but may be different angles. Here, when the angle θ formed by the adjacent straight portions is less than 174 degrees, the shape of the bulging portion in a side cross-sectional view becomes an extreme shape that partially protrudes, and the contact resistance with the slab increases. Wear damage is likely to occur in the bulging portion. On the other hand, when the angle θ formed by the adjacent straight portions exceeds 179.97 degrees, the number of straight portions increases and the processing of the bulging portion becomes complicated, resulting in an increase in manufacturing cost. From the above, the angles θ1 and θ2 formed by the adjacent straight line portions L1 to L3 are set in the range of 174 degrees or more and 179.97 degrees or less, respectively, but the lower limit is 178.0 degrees, and further 179.0 degrees. It is preferable to set the upper limit to 179.90 degrees.

The above-mentioned connection point X1 between the uppermost straight line portion L1 and the next straight line portion L2, the connection point X2 between the straight line portion L2 and the next straight line portion L3, and the lower position P2 from the upper end position of the long side 11 to the long side 11 Are provided at different intervals S1 to S3 in the vertical direction. In addition, you may provide each connection location X1, X2 and the lower position P2 by the equal space | interval S about a part or all of the up-down direction of the long side 11. FIG. Here, the uniform interval S includes a case where each interval differs within a range of ± 20% (preferably ± 5%) with respect to an average value of each interval.

As shown in FIG. 2, the maximum height h of the bulging portion 22 with the straight line L4 connecting the upper position P1 and the lower position P2 as the base (the connection between the first straight portion L1 and the second straight portion L2 from the top). The height of the portion X1) is in the range of 0.2 mm or more and 5 mm or less. Here, when the maximum height h is less than 0.2 mm, the amount of protrusion of the bulging portion toward the space is too small, and the surface shape of the bulging portion cannot follow the solidification shrinkage of the slab, and the bulging portion A gap is formed between the surface of the steel and the solidified shell formed on the mold contact surface side of the molten steel. On the other hand, when the maximum height h exceeds 5 mm, the longitudinal section of the bulge part becomes an extreme shape that partially protrudes, the contact resistance with the slab increases, and wear damage occurs in the bulge part. It becomes easy. From the above, the maximum height h of the bulging portion 22 is set in the range of 0.2 mm to 5 mm, but the lower limit is preferably 0.5 mm, more preferably 0.55 mm, and the upper limit is 2.5 mm. Furthermore, it is preferable to set it as 2.2 mm.

The formation position of the bulge part shown above, the number of straight parts constituting the bulge part, the angle formed by the adjacent straight parts, and the maximum height h of the bulge part (that is, the formation position and shape of the multitaper) Is based on FEM analysis (analysis using the finite element method) considering the solidification shrinkage of the three-dimensional slab and the thermal deformation of the mold based on the conditions shown below and the actual measurement results. It is preferable to determine within the above-mentioned range.
1) Shape of slab, size of slab, or casting conditions (for example, casting temperature, drawing speed, mold cooling conditions, etc.).
2) Physical quantities derived from components of cast steel (for example, liquid phase temperature, solid phase temperature, transformation temperature, linear expansion coefficient, rigidity value, etc.).
3) The amount of contact heat transfer between the mold and the slab (the amount of shrinkage of the slab is greatly affected by this amount).
Since this contact heat transfer amount is disclosed in Japanese Patent Application Laid-Open No. 2008-49385, the detailed contents thereof are omitted.

Each of the long sides 11 and 12 has a long side base material 23 formed of copper or a copper alloy, and a reinforcing coating 20 formed on the inner surface of the long side base material 23. 1 and 3, each of the short sides 13 and 14 has a short side base material 24 formed of copper or a copper alloy, and the short side base material 24 is an upper end of the short side lower part 18. The short side upper base material 25 which is a base material of the short side upper portion 17 and the short side lower base material 26 which is a base material of the short side lower portion 18 are connected. Further, the short sides 13 and 14 are reinforcing films formed respectively on the inner surface of the short side base material 24 (short side upper base material 25 and short side lower base material 26) and on the inner corner of the short side lower base material 26. 21 and a protective coating 27 formed on the side end face of the short side upper base material 25 and having ductility.

Here, the reinforcing coatings 20 and 21 may be a thermal spray coating made of a Cr—Si—B alloy based on Ni or Co, or a carbide (eg, WC) on a Co, Ni, or Co—Ni alloy. In addition, a sprayed coating made of a composite material to which any one or more of nitride (for example, TiN) and boride (for example, CrB) is added can be used. By making the reinforcing coatings 20 and 21 sprayed coatings, the thickness of the reinforcing coatings 20 and 21 can be easily adjusted. The protective film 27 can be a metal film having excellent ductility such as Ni plating.

In the case of a thermal spray coating made of a Cr-Si-B alloy based on Ni or Co, the reinforcing coatings 20 and 21 are densified by performing a fusing treatment, and the reinforcing coating 20 and the long-side base material 23 are formed. The connectivity between the reinforcing coating 21 and the short side base material 24 can be improved, and the life of the reinforcing coatings 20 and 21 can be extended. On the other hand, in the case of a thermal spray coating made of a composite material in which any one or more of carbide, nitride, and boride is added to a Co, Ni, or Co—Ni alloy, it occurs in the reinforcing coatings 20 and 21. It is possible to further prevent abrasion and improve the abrasion resistance of the reinforcing coatings 20 and 21.

The thicknesses of the reinforcing film 20 formed on the inner surface of the long side base material 23 and the reinforcing film 21 formed on the inner surface of the short side base material 24 are 0.01 mm or more and 5 mm or less, for example, 0.5 mm.
As shown in FIGS. 3A and 3B, the protective film 27 provided on the short side upper base material 25 is arranged so that the short side upper base material 25 extends from the side end surface 28 to the center in the width direction of the short side upper base material 25. The distance a (0.5 mm or more and 1 mm or less, for example, 0.8 mm) is removed (for example, ground), the removed portion is filled with a metal film having excellent ductility, and further formed on the inner surface of the short side base material 24. It is formed by laminating until the same height as the surface of the reinforcing film 21 is reached.

Further, as shown in FIGS. 3A, 3B, and 4, the reinforcing film 21 formed on the inner corner of the short side lower base material 26 has the short side lower base material 26 short from the side end face 28. A distance b (0.5 mm or more and 1 mm or less, for example, 0.8 mm) at the center in the width direction of the lower side base material 26, and a distance c (0.3 mm or more and 1 mm from the inner surface to the outer surface side of the short side lower base material 26. In the following, for example, 0.7 mm) is removed (for example, ground), and the removed portion is filled with a sprayed coating, and further, the surface is the same height as the surface of the reinforcing coating 21 formed on the inner surface of the short side base material 24. It is formed by laminating.

And as shown in FIG. 4, the dimension d of the chamfering performed with respect to the width direction of the short sides 13 and 14 is 0.3 mm or more and 1 mm or less, for example, 0.35 mm, and with respect to the thickness direction of the short sides 13 and 14. The dimension e of the chamfering performed is 0.3 mm or more and 2 mm or less, for example 0.35 mm. Therefore, the chamfering applied to the inner corner portion of the short side lower portion 18 is applied to the portion of the reinforcing film 21 formed on the inner corner portion of the short side lower base material 26. As a result, a space portion 19 is formed between the inner corner portion of the short side lower portion 18 and the inner surfaces of the long sides 11 and 12.

In the present embodiment, the space portion 19 is formed at the inner corner portion of the short side lower portion 18, which is the lower region including the meniscus portion of the short sides 13, 14, but abuts against the inner surface of the long sides 11, 12. It is also possible to chamfer the entire inner corner of the short side so that the inner corner of the short side does not contact the inner surfaces of the long sides 11 and 12. In addition, the shape of the chamfer provided on the entire inner corner of the short side can be the same as the shape of the chamfer described in the embodiment, and the inner corner of the short side and the inner surfaces of the long sides 11 and 12 The shape of the space formed between the two can be the same as the shape of the space 19 described in the embodiment.

Then, the effect | action of the continuous casting mold 10 which concerns on one embodiment of this invention is demonstrated.
During continuous casting, the inner corners of the short side lower portion 18 including the region where the thermal expansion is remarkable inside the short sides 13 and 14 are chamfered, and the inner corners of the short side lower portion 18 and the inner surfaces of the long sides 11 and 12 are chamfered. By forming the space 19 therebetween, the inner corner portion of the short side lower portion 18 can be thermally expanded to the inner surface side of the long sides 11 and 12 without being restricted during continuous casting. For this reason, it is possible to prevent the strain associated with the thermal expansion constraint from being localized in the inner corners of the short sides 13 and 14 and to prevent the occurrence of stress concentration due to the localized strain.

As a result, even if a reinforcing film made of a hard film is formed on the inner corners of the short sides 13 and 14 opposed to each other between the long sides 11 and 12 opposed to each other, the reinforcing film formed during continuous casting is lacking. Can be prevented. As a result, it becomes possible to stably provide a reinforcing coating made of a hard coating on the inner corners of the short sides 13 and 14, and the inner corners of the short sides 13 and 14 that have been a problem in the multitaper mold. Thus, it is possible to prevent early wear damage of the multi-taper mold and to extend the life of the multi-taper mold.

The chamfer dimension formed at the inner corner of the short side lower portion 18 is 0.3 mm or more and 1 mm or less with respect to the width direction of the short sides 13 and 14, and 0 with respect to the thickness direction of the short sides 13 and 14. Since it is 3 mm or more and 2 mm or less, even if the space portion 19 is formed between the inner surface of the long sides 11 and 12 and the inner corner portion of the short side lower portion 18, it is possible to prevent the molten steel from entering (inserting). . For this reason, molten steel does not solidify in the space part 19, and the slab can be easily moved in the continuous casting mold 10.

(Experimental example 1)
The long side in which a reinforcing coating made of a thermal spray coating of a Cr-Si-B alloy based on Co is formed on the inner surface of the long side base material, the inner surface of the short side upper base material, and the short side lower base material A reinforcing coating made of a thermal spray coating of a Cr-Si-B alloy based on Co is formed on the inner surface of the lower side base metal and Ni plating on the side of the upper side base metal. A continuous casting mold was constructed using the short side on which the protective film was formed, and the strain generated at the inner corner of the short side during continuous casting was determined by the finite element method. Here, a chamfering process is performed on the inner corner of the lower part of the short side to form an angle of 45 degrees with the inner surface of the short side (lower part of the short side).
FIG. 5 shows the strain level generated in the meniscus portion when the width (chamfer chamfer dimension) of the surface formed by chamfering is changed, and FIG. 6 shows the strain level generated at a position 400 mm below the meniscus. 5 and 6, the fracture strain rate obtained by dividing the strain obtained by calculation by the strain at the time of fracture of the reinforcing film (standardized) is used.

As shown in FIGS. 5 and 6, by providing a reinforcing coating made of a Co-based Cr-Si-B alloy and chamfering the inner corner of the lower part of the short side, the breaking strain rate generated can be reduced. , Fracture strain rate generated in the meniscus portion of the inner corner portion of the short side when Ni plating is formed on the side end surface of the short side (that is, the upper limit level of the preferred fracture strain rate in which no chipping occurs in the inner corner portion of the short side )), Which is less than 6.3%, and chipping of the inner corners at the bottom of the short side can be prevented. In addition, as the oblique chamfer dimension increases, the breaking strain rate gradually decreases. However, when the oblique chamfer dimension is 0.5 mm or more, the effect of decreasing the fracture strain rate is not observed. Therefore, it can be seen that it is sufficient that the bevel chamfer dimension of the chamfer provided at the inner corner of the reinforcing coating is 0.5 mm.

(Experimental example 2)
The long side in which a reinforcing coating made of a thermal spray coating of a Cr-Si-B alloy based on Co is formed on the inner surface of the long side base material, the inner surface of the short side base material, and the inner side of the short side base material A continuous casting mold is formed using a short side on which a reinforcing coating made of a thermal spray coating of a Co-based Cr-Si-B alloy based on Co is formed at the corner, and at the inner corner of the short side during continuous casting The generated strain was determined by the finite element method. Here, the inner corner of the short side is chamfered to form an angle of 45 degrees with the inner surface of the short side.
FIG. 5 shows the strain level generated at the meniscus portion when the oblique chamfer dimension formed by chamfering is changed, and FIG. 6 shows the strain level generated at a position 400 mm below the meniscus.

As shown in FIGS. 5 and 6, a reinforcing coating made of a Cr-Si-B alloy based on Co is provided, and the inner corner of the short side is chamfered to give a fracture strain rate of 6.3. The value can be made less than%, and chipping of the inner corners of the short sides can be prevented. It can also be seen that the chamfer dimension of the chamfer provided at the inner corner of the reinforcing coating is sufficient to be 0.5 mm.

(Experimental example 3)
A long side formed with a thermal spray coating of a Ni—Cr alloy spray coating on the inner surface of the long-side base material, and an inner surface of the short-side base material and an inner corner of the short-side base material are respectively Ni—Cr. Short side chamfered so that a 45 ° sloped surface is formed at the inner corner of the reinforcing coating formed at the inner corner of the short side base material, with a reinforcing coating made of a thermal spray coating of an alloy The continuous casting mold was constructed using and, and the strain generated at the inner corner of the short side during continuous casting was determined by the finite element method. Here, the inner corner of the short side is chamfered to form an angle of 45 degrees with the inner surface of the short side.
FIG. 5 shows the strain level generated at the meniscus portion when the oblique chamfer dimension formed by chamfering is changed, and FIG. 6 shows the strain level generated at a position 400 mm below the meniscus.

When a reinforcing film made of a Ni-Cr alloy is formed and the inner corner of the reinforcing film is not chamfered (the chamfer dimension is 0 mm), as shown in FIG. 5, the breaking strain generated in the meniscus part The rate is about 115%, and it can be expected that chipping occurs at the inner corner of the short side. In addition, as the oblique chamfer dimension applied to the inner corner of the short side increases, it is possible to reduce the breaking strain rate generated in the meniscus, but the oblique chamfer dimension provided at the inner corner of the reinforcing coating. Even when the thickness is 0.6 mm or more, the fracture strain rate is about 30%, and the “upper limit level of the fracture strain rate with less chipping damage” obtained from experience through actual use of a continuous casting mold is 15.6%. Over. The breaking strain rate generated at a position 400 mm below the meniscus is a value near 15.6% regardless of the size of the chamfer chamfer dimension as shown in FIG. For this reason, there is a high possibility that the inner corner portion of the short side is chipped.

(Experimental example 4)
A long side with a Co-based Cr-Si-B alloy spray coating formed on the inner surface of the long side base metal, and a Co-based Cr base on the inner surface of the short side base material -A continuous casting mold is formed by using a reinforcing coating made of a thermal spray coating of an Si-B alloy and a short side formed with a protective coating made of a Co-Ni alloy plating on the side of the short side base material. The strain generated at the inner corner of the short side during continuous casting was determined by the finite element method. Here, the inner corner of the short side is chamfered to form an angle of 45 degrees with the inner surface of the short side.
FIG. 5 shows the strain level generated at the meniscus portion when the oblique chamfer dimension formed by chamfering is changed, and FIG. 6 shows the strain level generated at a position 400 mm below the meniscus.

As shown in FIG. 5, if a protective film made of Co—Ni alloy plating is provided and the inner corner of the protective film is not chamfered, the breaking strain generated in the meniscus portion as shown in FIG. The rate is about 55%, and there is a high possibility of chipping at the inner corners of the short sides. In addition, as the oblique chamfer dimension applied to the inner corner of the short side is increased, it is possible to reduce the breaking strain rate generated in the meniscus, but the oblique chamfer dimension provided at the inner corner of the protective coating. Is 0.6 mm or more, the breaking strain rate is about 10%, exceeding the “preferable upper limit level of breaking strain rate” of 6.3%. On the other hand, the breaking strain rate generated at a position 400 mm below the meniscus has a value of less than 6.3% as shown in FIG. As a result, for this reason, when a protective film made of Co-Ni alloy plating is provided, even if the inner corner of the protective film is chamfered, the inner corner of the short side corresponding to the meniscus is not chipped. May occur.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above-described embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included.
Further, the present invention also includes a combination of components included in the present embodiment and other embodiments and modifications.
For example, in this embodiment, the long side is a multitaper, but the long side and the short side may be a multitaper.
In this embodiment, chamfering is performed on the inner corner of the reinforcing film provided on the side of the short side base material constituting the short side, but the reinforcing film does not exist on the short side base material. Furthermore, it is also included in the present invention to chamfer the inner corner of the short side base material.

10: Continuous casting mold, 11, 12: Long side, 13, 14: Short side, 15: Cast piece forming part, 16: Molten steel, 17: Upper part of short side, 18: Lower part of short side, 19: Space part, 20, 21: Reinforcing film, 22: bulging part, 23: long side base material, 24: short side base material, 25: short side upper base material, 26: short side lower base material, 27: protective film, 28: side end face

Claims (5)

In a continuous casting mold having a long side opposed to each other and a short side arranged oppositely between the long sides,
Chamfering the inner corner of the short side that contacts the inner surface of the long side, or the inner corner of the lower side that includes the meniscus portion of the short side and contacting the inner surface of the long side, A continuous casting mold, wherein a space is formed between an inner corner and an inner surface of the long side to prevent damage to the inner corner of the short side. 2. The continuous casting mold according to claim 1, wherein the dimension of the chamfer is 0.3 mm or more and 1 mm or less with respect to the width direction of the short side and is 0.3 mm or more and 2 mm or less with respect to the thickness direction of the short side. A continuous casting mold characterized by being. 3. The continuous casting mold according to claim 1, wherein a wear-resistant reinforcing film made of a sprayed coating is formed on an inner corner portion of the short side where the chamfering is performed. Casting mold. 4. The continuous casting mold according to claim 3, wherein the thermal spray coating is made of a Cr-Si-B alloy based on Ni or Co. 4. The continuous casting mold according to claim 3, wherein the thermal spray coating is made of a composite material obtained by adding one or more of carbide, nitride, and boride to a Co, Ni, or Co—Ni alloy. Continuous casting mold characterized by.

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