JP4659706B2 - Continuous casting mold - Google Patents

Description

The present invention relates to a continuous casting mold used for manufacturing a slab.

Conventionally, molten steel is supplied to a continuous casting mold (hereinafter also simply referred to as a mold) 80 shown in FIG. 10 to cast a slab having a plate width of 600 mm or more. The mold 80 is a state in which a pair of short piece members (also referred to as short side members) 81 and 82 composed of copper plates opposed to each other with a gap therebetween, and the short piece members 81 and 82 sandwiched from both sides in the width direction. And a pair of long piece members (also referred to as long side members) 83 and 84 formed of copper plates opposed to each other.
The short piece members 81 and 82 are mirror-symmetrical and have the same configuration, and a large number of water guide grooves are provided in the vertical direction on the back side. The back plate (cooling box) is provided on the back side of the short piece members 81 and 82 by bolts. (Also called) 85 and 86 are fixed. The long piece members 83 and 84 are also provided with a large number of water guide grooves in the vertical direction on the back surface side, and back plates 87 and 88 are fixed to the back surface side of the long piece members 83 and 84 by bolts (for example, , See Patent Document 1).
It should be noted that bolts 89 are attached to both ends of the back plates 87 and 88 fixed to the opposing long piece members 83 and 84, and are fixed with nuts 90 via springs (not shown).

During continuous casting, cooling water is poured into a number of water guide grooves, and while cooling the short piece members 81 and 82 and the long piece members 83 and 84, molten steel is poured from above the mold 80 to perform initial solidification of the molten steel. The solidified slab is drawn continuously at a constant speed from below the mold to produce a slab.
In the solidification process of the molten steel, solidification shrinkage occurs, so that a gap is generated between the inner surface 91 of the mold and the solidified shell formed on the mold contact surface side of the molten steel in the slab drawing direction. The cooling efficiency of the part was lower than the other parts, and solidification delay occurred.
Therefore, the interval w between the short piece members 81 and 82 which is wider than between the long piece members 83 and 84 is narrowed corresponding to the solidification contraction shape of the slab in the drawing direction of the slab.

JP 2005-59034 A

However, the distance between the pair of opposed long pieces constituting the conventional mold does not correspond to the solidified shrinkage shape of the slab, and the long pieces are inclined at the same rate from the molten metal surface position to the lower end position. (Also called a single taper). For this reason, in the solidification process of the molten steel, a gap is generated between the inner surface of the long piece member side of the mold and the solidified shell formed on the mold contact surface side of the molten steel in the slab drawing direction. As a result, the cooling efficiency of the corner portion on the long piece member side of the slab is lower than the other portions, and the solidification delay of the slab at the mold corner portion occurs, leading to a reduction in the quality of the slab.
In particular, this phenomenon becomes conspicuous as the slab drawing speed is increased, and there is a limit to further improving the production efficiency of the slab.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a continuous casting mold that can suppress and further prevent the delay in solidification of the slab at the mold corner and can manufacture a slab of good quality. And

The continuous casting mold according to the present invention that meets the above-mentioned object is arranged to face each other with an interval of 600 mm or more and 3000 mm or less at the upper end, and a pair of short piece members that can change the interval, and 50 mm to 300 mm at the upper end. A pair of long piece members arranged opposite to each other with the short piece member sandwiched from both sides in the width direction with the following interval, and supplied to the space formed by the short piece member and the long piece member In the continuous casting mold for producing the slab, the molten steel is drawn down while being cooled and solidified by the short piece member and the long piece member,
The short piece member and the long piece member have a vertical length of 600 mm or more and 1200 mm or less,
The inner cross-sectional shape of the pair of long piece members is the same in the width direction, and as the distance from the molten steel to the lower side of the molten steel increases, the taper rate increases at a reduced rate.
Moreover, the continuous casting mold is characterized in that the inner cross-sectional shape of the pair of long piece members satisfies the following expression in a range from the molten steel surface to 200 mm downward and in a range lower than 200 mm: .
(1) 0 ≦ X ₁ ≦ 200
−3.85 × 10 ⁻⁸ X ₁ ² + 2.54 × 10 ⁻⁵ X ₁ ≦ Y ₁ ≦ −14.05 × 10 ⁻⁸ X ₁ ² + 8.48 × 10 ⁻⁵ X ₁
(2) 200 <X ₁
1.78 × 10 ⁻³ × lnX ₁ −5.89 × 10 ⁻³ ≦ Y ₁ ≦ 4.91 × 10 ⁻³ × lnX ₁ −14.72 × 10 ⁻³
The distance X ₁ is downward from the melt surface of the longitudinal strip (mm), Y ₁ is the amount of decrease in the opposing distance of the strips on the basis spacing apart at the melt surface position of the opposing longitudinal strips Is divided by the reference interval.

In the continuous casting mold according to the present invention, the inner cross-sectional shape of the pair of short piece members is the same in the width direction, and the taper ratio increases as the distance from the molten steel to the lower side increases. The taper becomes a multi-taper with a reduced rate, and the inner cross-sectional shape of the pair of short piece members satisfies the following formulas in the range from the molten steel surface down to 200 mm and in the range below 200 mm: And
Moreover, it is preferable that the taper amount of the short piece member is larger than that of the long piece member.
(1) 0 ≦ X ₂ ≦ 200
−3.85 × 10 ⁻⁸ X ₂ ² + 2.54 × 10 ⁻⁵ X ₂ ≦ Y ₂ ≦ −14.05 × 10 ⁻⁸ X ₂ ² + 8.48 × 10 ⁻⁵ X ₂
(2) 200 <X ₂
1.78 × 10 ⁻³ × lnX ₂ −5.89 × 10 ⁻³ ≦ Y ₂ ≦ 4.91 × 10 ⁻³ × lnX ₂ −14.72 × 10 ⁻³
Here, X ₂ is a distance (mm) downward from the molten metal surface of the short piece member, and Y ₂ is a reduction amount of the facing distance of the short piece member with the interval at the molten metal position of the opposed short piece member as a reference interval. The value divided by the interval.

In the continuous casting mold according to the present invention, both sides in the width direction of each of the short piece members are shaved corresponding to the inner shape of the long piece member, and each of the short piece members is changed in order to change the interval of the short piece members arranged to face each other. When the short piece member is inclined, it is preferable that a gap generated between both end faces of the short piece member and the inner face of the long piece member is 0.3 mm or less.
In the continuous casting mold according to the present invention, it is preferable that a coating layer by thermal spraying is formed on the inner surface side of the short piece member.
In the continuous casting mold according to the present invention, it is preferable that a coating layer by thermal spraying is formed on the inner surface side of the long piece member.

The continuous casting mold according to any one of claims 1 to 5, wherein the interval between the opposing short piece members and the interval between the opposing long piece members correspond to the solidification shrinkage shape of the slab, and the inner cross-sectional shape of the pair of long piece members is predetermined. Since the shape is defined, the slab solidification delay at the mold corner can be suppressed and further prevented, and a slab of good quality can be manufactured.
Further, since the solidification delay of the slab at the mold corner can be suppressed and further prevented, the slab drawing speed can be further improved, and the production efficiency of the slab can be improved as compared with the current situation.
In addition, because the inner cross-sectional shape of the pair of long piece members is defined as a predetermined shape, it is possible to suppress and further prevent the solidification delay of the long piece side corner portion of the slab, which could not be improved with conventional molds, and breakout Further improvements in stability and high productivity can be achieved.

In particular, since the continuous casting mold according to claim 2 defines the inner cross-sectional shape of the pair of short piece members to a predetermined shape, the solidification delay of the short piece side corner portion can be suppressed and further prevented, and breakout can be prevented. Thus, further improvements can be achieved with respect to stability and high productivity.
In the continuous casting mold according to claim 3, since both sides in the width direction of each short piece member are cut in correspondence with the inner shape of the long piece member, between the both end faces of the short piece member and the inner face of the long piece member. The generated gap can be reduced as much as possible. In addition, although the short piece member arranged oppositely inclines each short piece member in order to change the space | interval, by making the magnitude | size of the clearance gap produced in that case into 0.3 mm or less, for example, the molten steel leak from a clearance gap is carried out. Can be prevented.
In the continuous casting mold according to claims 4 and 5, since the coating layer by thermal spraying is formed on the inner surface side of the short piece member, the life of the short piece member can be extended. Moreover, since the coating layer by thermal spraying is formed on the inner surface side of the long piece member, the life of the long piece member can be extended.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIGS. 1A and 1B, a continuous casting mold (hereinafter also simply referred to as a mold or a four-set mold) 10 according to an embodiment of the present invention is disposed to face each other with a gap W1. In addition, a pair of short piece members (also referred to as short side members) 11 and 12 capable of changing the interval W1, and a pair of long piece members (which are opposed to each other with the short piece members 11 and 12 sandwiched from both sides in the width direction) (Also referred to as long side members) 13 and 14, and the molten steel supplied into the space 15 formed by the short piece members 11 and 12 and the long piece members 13 and 14, the short piece members 11 and 12 and the long piece member The slab having a plate width of 600 mm or more is manufactured by cooling down at 13 and 14 and pulling it downward while solidifying. The short piece members 11 and 12 and the long piece members 13 and 14 are made of copper or a copper alloy (also referred to as a short side copper plate or a long side copper plate). This will be described in detail below.

Each short piece member 11, 12 has a width of about 50 mm or more and 300 mm or less, and a vertical length of about 600 mm or more and 1200 mm or less. Further, each of the long piece members 13 and 14 has, for example, a width (inner width of the mold) of about 600 mm or more and 3000 mm or less and a vertical length of the same length as that of the short piece member.
Accordingly, the interval W1 between the pair of short pieces 11 and 12 arranged to face each other is about 600 mm to 3000 mm, the interval W2 between the pair of long pieces 13 and 14 is about 50 mm to 300 mm, and the mold 10 The vertical length is about 600 mm or more and 1200 mm or less. In addition, the space | interval W1 can change the short piece members 11 and 12 arrange | positioned facing within the above-mentioned range.
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.

The intervals W1 and W2 between the pair of short piece members 11 and 12 and the pair of long piece members 13 and 14 are narrowed according to the solidification contraction shape of the slab in the slab pulling direction.
In particular, the cross-sectional shape inside the long piece members 13 and 14 (surface side in contact with the molten steel) is the same in the width direction of the long piece members 13 and 14, and as shown in FIG. As the distance from the distance increases, the taper rate increases, that is, a multitaper shape. The multitaper is a slab solidification shrinkage profile in the mold 10 (from the meniscus position 16 to the mold outlet 17) using one or both of a curve (defined by a plurality of functions) and a plurality of straight lines. It is approximated and applied to the inner cross-sectional shape of the long piece members 13 and 14.
Hereinafter, the multitaper determination method will be described.

Multitaper is an FEM analysis that considers the following conditions, and also considers solidification shrinkage of the three-dimensional slab and thermal deformation of the mold based on the actual measurement results (analysis using the finite element method) It is demanded by.
B) Slab shape, slab size, or casting conditions (for example, casting temperature, drawing speed, mold cooling conditions, etc.).
B) Physical quantities derived from the components of cast steel (for example, liquid phase temperature, solid phase temperature, transformation temperature, linear expansion coefficient, rigidity value, etc.).
C) 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).
This amount of contact heat transfer is greatly influenced by, for example, the type of lubricant used at the time of casting or the difference in the surface properties of the slab (depending on the steel type, oscillation conditions, and type of lubricant). Therefore, it is necessary for determining the multitaper to grasp the actual amount of contact heat transfer for each casting condition as accurately as possible.

The actual amount of contact heat transfer is ascertained based on the temperature difference (and flow rate) between the inlet side and outlet side of the mold cooling water and the temperature measured by the thermocouple installed in the mold.
Further, it may be necessary to consider thermal deformation of the mold. In the corner-matching portion of the mold with weak rigidity or the four-set mold, the mold thermal deformation is partially reverse-tapered in the shrinking direction of the slab, and the amount thereof cannot be ignored. In such a case, a multitaper that takes into account the thermal deformation of the mold is applied in advance so that when the mold is thermally deformed, the multitaper matches the contraction profile of the slab.
An example of the analysis result obtained based on the above conditions is shown in FIG. The vertical axis in FIG. 2 indicates the taper ratio, that is, the length of the long piece members 13 and 14 with the interval at the molten metal surface (meniscus) position of the opposed long piece members 13 and 14 shown in FIG. The ratio (%) of the value obtained by dividing the decrease amount of the facing distance by the reference interval is shown, and the horizontal axis shows the distance (mm) from the hot water surface of the long piece members 13 and 14 downward.

The appropriate range of the taper ratio shown in FIG. 2 is expressed by the following relational expression. Incidentally, X ₁ is (corresponding to the horizontal axis of FIG. 2) the distance downward from the melt surface of the longitudinal strip, Y ₁ is divided by the reference interval the decrease of the opposing distance of opposing longitudinal strips value (FIG. 2 Corresponding to the taper rate). Therefore, the inner cross-sectional shape of the long piece member on one side is half (1/2) of the following relational expression.
(1) 0 ≦ X ₁ ≦ 200
−3.85 × 10 ⁻⁸ X ₁ ² + 2.54 × 10 ⁻⁵ X ₁ ≦ Y ₁ ≦ −14.05 × 10 ⁻⁸ X ₁ ² + 8.48 × 10 ⁻⁵ X ₁
(2) 200 <X ₁
1.78 × 10 ⁻³ × lnX ₁ −5.89 × 10 ⁻³ ≦ Y ₁ ≦ 4.91 × 10 ⁻³ × lnX ₁ −14.72 × 10 ⁻³

Furthermore, the inner cross-sectional shape of the pair of short piece members 11 and 12 is also the following in the range from the molten steel surface down to 200 mm and the range below 200 mm over the width direction of the short piece members 11 and 12. Satisfy the formula Accordingly, the inner cross-sectional shape of the short piece member on one side is half (1/2) of the following relational expression.
(1) 0 ≦ X ₂ ≦ 200
−3.85 × 10 ⁻⁸ X ₂ ² + 2.54 × 10 ⁻⁵ X ₂ ≦ Y ₂ ≦ −14.05 × 10 ⁻⁸ X ₂ ² + 8.48 × 10 ⁻⁵ X ₂
(2) 200 <X ₂
1.78 × 10 ⁻³ × lnX ₂ −5.89 × 10 ⁻³ ≦ Y ₂ ≦ 4.91 × 10 ⁻³ × lnX ₂ −14.72 × 10 ⁻³
Here, X ₂ is a distance (mm) downward from the molten metal surface of the short piece member, and Y ₂ is a reduction amount of the facing distance of the short piece member with the interval at the molten metal position of the opposed short piece member as a reference interval. The value divided by the interval.

Here, FIG. 3 shows an application example of the multitaper obtained using the above-described relational expression when the interval W1 between the short pieces is 1000 mm and the interval W2 between the long pieces is 250 mm. Since the numerical values obtained from the relational expression described above are values obtained from the distance between the pair of short piece members and values obtained from the distance between the pair of long piece members, the shape shown in FIG. It is half.
Since the interval W1 between the short piece members opposed to each other is wider than the interval W2 between the long piece members, the amount of solidification shrinkage increases, and the cross-sectional shapes of the short piece member and the long piece member are the shapes shown in FIG.

In addition, as shown to FIG. 1 (A), (B), the width direction both sides of each short piece member 11 and 12 are shaved corresponding to the inner surface side shape of the long piece members 13 and 14. FIG. Note that, as described above, the inclination of each of the short piece members 11 and 12 arranged to face each other is changed according to the interval W1. Here, when each short piece member 11, 12 is inclined, a gap is generated between both end faces of the short piece members 11, 12 and the inner face of the long piece members 13, 14.
However, it is possible to prevent molten steel leakage from the contact portion between the long piece members 13 and 14 and the short piece members 11 and 12 by designing and manufacturing the gap amount to be 0.3 mm or less.

A coating layer by thermal spraying is formed on the inner surface side of the short piece members 11 and 12, and a coating layer by thermal spraying is formed on the inner surface side of the long piece members 13 and.
The coating layer for thermal spraying may be formed over the entire surface of the copper plate used for one or both of the short piece member and the long piece member, and plural kinds of components may be formed on the copper plate. May be formed in different regions in the vertical direction according to the function of each component.
Each of the short piece member and the long piece member described above is manufactured by forming a coating layer on the surface of the copper plate and then performing a conventionally known machining process for a predetermined shape within the range of the above-described mathematical formula.

As this coating layer, there are a fusing type that is used by heat treatment after spraying the copper plate surface, and a fusingless type that is used without heat treatment.
As the fusing type material, a Cr—Si—B based alloy based on Ni or Co can be used, and a cermet added to it can be used as necessary.
The fusingless type material includes any one of Co, Ni, or alloys thereof, carbides such as WC (tungsten carbide), nitrides such as TiN, and borides such as CrB. Or what added 2 or more can be used.
Any of the types of materials described above can be applied to the short piece member and the long piece member, but considering the change in the shape of the copper plate after the heat treatment is completed, a fusing type material is used for the short piece member. It is preferable to apply a fusingless type material to each of the long piece members.
The coating layer may be plated. As a material for the plating, for example, a Co alloy such as Co—Ni, a Ni alloy such as Ni—Fe, or Ni can be used.

Next, examples carried out for confirming the effects of the present invention will be described.
First, when manufacturing a slab using a mold in which the distance between a pair of short pieces arranged opposite to each other is set to 1000 mm, the results of numerical analysis of the thickness of the solidified shell formed at the mold corner are shown in FIGS. This will be described with reference to FIG. 5 and 6 show the results when the distance between the short piece members of the mold shown in FIG. 4 numerically analyzed with the distance between the short piece members being 1000 mm is 1200 mm and 1400 mm, respectively, by inclining the short piece members.
The distance between the pair of long piece members arranged to face each other is 250 mm.

4 to 6, each (A) is a result of using the current single taper (taper (decrease) amount per 1 m from the molten metal surface: short piece member interval 15 mm, long piece member interval 1.25 mm), (B) is a result of the inner cross-sectional shape of the long piece member and the short piece member being both in a predetermined shape within the above-described condition range, and (C) is a single taper having a large inclination angle (water surface) Taper (reduction amount per 1 m from the distance: 2.5 mm between the long piece members) and the inner cross-sectional shape of the short piece member as a predetermined shape within the above-mentioned condition range, (D) shows the inside of the long piece member The cross-sectional shape is the above-described current single taper, and the inner cross-sectional shape of the short piece member is a predetermined shape within the above-described condition range. In addition, in FIGS. 4-6, each solidified shell thickness of the position of 200 mm (thick line), the position of 400 mm (dashed line), and the position of 790 mm (thin line) from the molten metal surface position is shown.

As is clear from FIG. 4B, the inner cross-sectional shape of the long piece member and the short piece member are both set to a predetermined shape within the above-described condition range, so that the thickness of the solidified shell at the mold corner is equal to that of other portions. It can be seen that the cooling was performed under good conditions. This is clear even when compared with the other FIGS. 4 (A), (C), and (D).
As apparent from FIGS. 5 (B) and 6 (B), the gap between the pair of short piece members arranged opposite to each other is easily increased, so that a gap is easily generated between the inner surface of the mold and the solidified shell. The thickness of the solidified shell at the mold corner is gradually reduced as compared with FIG. However, it can be confirmed that the thickness of the solidified shell can be increased even when compared with other conditions shown in FIGS. 5 (A), (C), (D), and FIGS. 6 (A), (C), (D). It was.

Subsequently, as a result of numerical analysis of the maximum gap amount (maximum gap amount) generated between the corner portion on the inner surface side of the short piece member and the formed solidified shell using the mold obtained from FIGS. 4 to 6. Will be described with reference to FIGS.
As is clear from FIGS. 7A to 7C, the conditions in FIGS. 4 to 6B are significantly different from those in FIGS. 4 to 6C. Although not, it was confirmed that the maximum gap amount could be reduced as compared with (A) of FIGS.
Furthermore, the result of numerical analysis of the maximum gap amount (maximum gap amount) generated between the corner portion on the inner surface side of the long piece member and the formed solidified shell using the mold obtained from FIGS. Will be described with reference to FIGS.
As is clear from FIGS. 8A to 8C, the conditions of FIG. 4 to FIG. 6B are compared with those of FIGS. 4 to 6 A, C, and D. Thus, it was confirmed that the maximum gap amount can be greatly reduced.

Here, the results of numerical analysis of the magnitude of the contact surface pressure exerted on the inner surface of the corner portion of the short piece member by the formed solidified shell using the mold obtained from FIGS. ) To (C). This contact surface pressure is prominently generated when the taper amount of the gap between the opposed short piece members or the taper amount of the gap between the opposed long piece members is set excessively than the solidification shrinkage amount of the slab. In this figure, the surface pressure generated at the corner of the short piece member is integrated over the width direction of the short piece member.
As is clear from FIGS. 9A to 9C, the condition of FIG. 4 to FIG. 6B is the contact surface pressure substantially equal to that of FIGS. 4 to 6C. However, it was confirmed that the contact surface pressure could be reduced as compared with (A) of FIGS. As a result, the problem of transverse cracks occurring at the corner of the slab can be reduced, wear at the corner at the bottom of the mold can be reduced, and the mold life can be extended.
From the above, it was confirmed that by using the continuous casting mold of the present invention, the solidification delay of the slab at the mold corner can be suppressed and further prevented, and a slab of good quality can be manufactured. Moreover, it has confirmed that it was effective also in the suppression of the fall of the corner quality of the slab resulting from an excessive taper (excessive restraint), and reduction of the early stage wear of a mold corner part.

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 embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, the case where the continuous casting mold of the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
In the above-described embodiment, the inner cross-sectional shape of the long piece member, and further the inner cross-sectional shape of the short piece member are defined by two continuous curves with a position of 200 mm downward from the molten metal surface position, In addition, although the lower limit and the upper limit of the specified curve are set, any shape in which the inner cross-sectional shape falls within this range is included in the scope of the present invention.

Further, the surface shape above the molten metal surface position of the long piece member and the short piece member may be a shape parallel to the respective back surface, and the inclination of the mold downward from the molten metal surface position is set at the upper end of the mold. It may be extended to. Furthermore, from the mold surface position of the mold to about 30 mm in the mold upper end direction, the downward inclination from the mold surface position of the mold may be extended, and the upper part thereof may be parallel to the respective back surfaces.

(A) and (B) are a perspective view and a partial perspective view, respectively, of a continuous casting mold according to an embodiment of the present invention. It is explanatory drawing which shows the appropriate range of the taper rate formed in the long piece member and short piece member of the same casting mold. It is explanatory drawing of the taper amount formed in the long piece member and short piece member of the same casting mold. (A)-(D) is explanatory drawing which shows the relationship between the short piece member and long piece member when the space | interval of the short piece member arrange | positioned facing each is 1000 mm, and solidified shell thickness. (A)-(D) is explanatory drawing which shows the relationship between the short piece member and long piece member when the space | interval of the short piece member arrange | positioned facing each is 1200 mm, and solidified shell thickness. (A)-(D) is explanatory drawing which shows the relationship between the short piece member and long piece member when the space | interval of the short piece member arrange | positioned facing each is 1400 mm, and solidified shell thickness. (A)-(C) is explanatory drawing which shows the maximum gap amount of the short piece member side corner part at the time of changing the space | interval of the short piece member arrange | positioned facing each. (A)-(C) is explanatory drawing which shows the largest gap amount of the long piece member side corner part at the time of changing the space | interval of the short piece member arrange | positioned facing each other. (A)-(C) is explanatory drawing which shows the contact surface pressure concerning the short piece member side corner part at the time of changing the space | interval of the short piece member arrange | positioned facing each. It is a top view of the casting mold for continuous casting which concerns on a prior art example.

10: mold for continuous casting, 11, 12: short piece member, 13, 14: long piece member, 15: space, 16: meniscus position, 17: mold outlet

Claims (5)

A pair of short piece members that are opposed to each other with an interval of 600 mm or more and 3000 mm or less at the upper end, and that can change the interval, and the short piece members that have an interval of 50 mm or more and 300 mm or less at the upper end on both sides in the width direction. A pair of long piece members that are opposed to each other in a state of being sandwiched between, and the molten steel supplied in the space formed by the short piece member and the long piece member is the short piece member and the long piece member In a continuous casting mold that produces slabs while cooling and solidifying and pulling down,
The short piece member and the long piece member have a vertical length of 600 mm or more and 1200 mm or less,
The inner cross-sectional shape of the pair of long piece members is the same in the width direction, and as the distance from the molten steel to the lower side of the molten steel increases, the taper rate increases at a reduced rate.
Moreover, the continuous casting mold is characterized in that the inner cross-sectional shape of the pair of long piece members satisfies the following expression in a range from the molten steel surface to 200 mm downward and in a range lower than 200 mm: .
(1) 0 ≦ X ₁ ≦ 200
−3.85 × 10 ⁻⁸ X ₁ ² + 2.54 × 10 ⁻⁵ X ₁ ≦ Y ₁ ≦ −14.05 × 10 ⁻⁸ X ₁ ² + 8.48 × 10 ⁻⁵ X ₁
(2) 200 <X ₁
1.78 × 10 ⁻³ × lnX ₁ −5.89 × 10 ⁻³ ≦ Y ₁ ≦ 4.91 × 10 ⁻³ × lnX ₁ −14.72 × 10 ⁻³
The distance X ₁ is downward from the melt surface of the longitudinal strip (mm), Y ₁ is the amount of decrease in the opposing distance of the strips on the basis spacing apart at the melt surface position of the opposing longitudinal strips Is divided by the reference interval. 2. The continuous casting mold according to claim 1 , wherein the inner cross-sectional shape of the pair of short piece members is the same in the width direction, and the taper ratio is increased as the distance from the molten steel surface downward is increased. In the multitaper where the rate of increase is small, and the inner cross-sectional shape of the pair of short piece members is in the range from the molten steel surface down to 200 mm and below 200 mm, Satisfied,
Moreover, the continuous casting mold is characterized in that the taper amount of the short piece member is larger than that of the long piece member.
(1) 0 ≦ X ₂ ≦ 200
−3.85 × 10 ⁻⁸ X ₂ ² + 2.54 × 10 ⁻⁵ X ₂ ≦ Y ₂ ≦ −14.05 × 10 ⁻⁸ X ₂ ² + 8.48 × 10 ⁻⁵ X ₂
(2) 200 <X ₂
1.78 × 10 ⁻³ × lnX ₂ −5.89 × 10 ⁻³ ≦ Y ₂ ≦ 4.91 × 10 ⁻³ × lnX ₂ −14.72 × 10 ⁻³
Here, X ₂ is a distance (mm) downward from the molten metal surface of the short piece member, and Y ₂ is a reduction amount of the facing distance of the short piece member with the interval at the molten metal position of the opposed short piece member as a reference interval. The value divided by the interval. 3. The continuous casting mold according to claim 1, wherein both sides in the width direction of each short piece member are shaved corresponding to the inner shape of the long piece member, and the interval between the short piece members arranged to face each other is changed. Therefore, when the respective short piece members are inclined, a gap formed between both end faces of the short piece member and the inner surface of the long piece member is set to 0.3 mm or less. The continuous casting mold according to any one of claims 1 to 3, wherein a coating layer by thermal spraying is formed on an inner surface side of the long piece member and the short piece member, and the coating layer of the long piece member is The coating material of the short piece member is formed by a fusingless type material that is used without being subjected to heat treatment after spraying the surface of the long piece member, and the coating layer of the short piece member is heat treated after spraying the surface of the short piece member. A mold for continuous casting, characterized in that it is formed of a fusing type material to be used. 5. The continuous casting mold according to claim 4, wherein the fusingless type material is added with one or more of carbide, nitride, and boride to Co, Ni, or an alloy thereof. And
The fusing type material is a Cr-Si-B alloy based on Ni or Co or a cermet added to the alloy, or a continuous casting mold.

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