JP4759326B2 - Continuous casting mold - Google Patents

Description

The present invention relates to a continuous casting mold for producing a slab by solidifying molten steel.

Conventionally, as shown in FIG. 4A, a continuous casting mold (hereinafter also simply referred to as a mold) 80 used in a continuous casting facility is a pair of short side members (also referred to as narrow cooling members or short piece members). 81 and 82, and a pair of long side members (also referred to as wide cooling members or long piece members) 83 and 84 disposed so as to sandwich the short side members 81 and 82, and the long side members 83 and 84 facing each other. Bolts (not shown) are attached to both ends of each, and fixed with nuts via springs. As shown in FIG. 4B, a sprayed layer 85 is formed on the molten steel contact surface side of the short side members 81 and 82, respectively, and Ni ( Nickel) or Co (cobalt) plating layers 86 are respectively formed.

The mold 80 has a configuration in which a pair of opposed short side members 81 and 82 are movable, and is formed in the mold 80 by adjusting the distance between the short side member 81 and the short side member 82. Cooling is performed while pouring high-temperature molten steel (for example, about 1600 ° C.) into the space 87 to continuously produce slabs. For this reason, due to the movement of the short side members 81, 82, the contact surface side of the short side members 81, 82 with the long side members 83, 84 is worn out. Therefore, in order to protect the long side member contact surface side of the short side member, a Ni plating layer 88 is formed on the long side member side end of the short side member, or the width of the short side member reduced by wear. In order to restore the dimensions, a Ni plating layer 89 is formed on the worn portion (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 57-82440 (Fig. 2)

However, the plating layer 88 formed on the contact surface side of the short side member 82 (the same applies to the short side member 81) with the long side member 83 is the sprayed layer formed on the contact surface side of the short side member 82 with the molten steel. Since the wear resistance is inferior to 85 (for example, the wear resistance of the Ni plating layer is about ¼ of the wear resistance of the Ni-based sprayed layer), the contact surface side of the plating layer 88 with the molten steel is partially As shown in FIG. 4B, a stepped portion 90 is formed on the contact surface side of the short side member 82 with the molten steel. And in this level difference part 90, for example, abnormal insertion of molten steel occurs, or due to this, chipping or peeling 91 occurs in the sprayed layer 85, and heat removal at the corners inside the mold 80 becomes worse. The problem occurs.
In particular, when restoring the width dimension of the short side member 82, the end of the short side member 82 is cut by about 0.5 mm in order to remove the remaining plating layer, and then the cut portion is plated. The layer 89 is applied and reproduced. For this reason, as shown by the alternate long and short dash line in FIG. 4B, the plating thickness of the short side member 82 increases by about 0.5 mm each time restoration is performed, so the above phenomenon occurs more remarkably.
This causes a breakout, and there is a possibility that the slab cannot be stably manufactured.
In addition, when both thermal spraying and plating are used for manufacturing a short piece member, both processes are required, the manufacturing process cannot be shortened and simplified, and the manufacturing cost is high and it is not economical. Inefficiency and productivity may be reduced.

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 capable of shortening and simplifying the manufacturing process as compared with the prior art and capable of stably producing a slab.

A continuous casting mold according to the present invention that meets the above-described object includes a pair of movable short-side members that are opposed to each other with a gap therebetween, and a pair of long-side members that are disposed with the short-side member interposed therebetween. In a continuous casting mold for producing a slab by pouring molten steel into a space formed by the pair of short side members and the pair of long side members to solidify the inner surface of the pair of long side members, A plating layer is formed , and a thermal spray layer is formed on the long side member contact surface of the short side member in contact with the long side member , and the hardness of the thermal spray layer on the long side member contact surface is the pair of long sides It is made smaller than the hardness of the plating layer formed on the inner facing surface of the member.

Continuous casting mold according to claim 1, wherein, since having a sprayed layer in a long side member contact surface of the short side members, can improve the wear resistance of the short side members, a conventional generator to have partial abrasion It can be suppressed and further prevented. As a result, for example, abnormal insertion of molten steel into the worn part, chipping or peeling of the sprayed layer due to this, and heat extraction failure at the corner inside the continuous casting mold can be suppressed and further prevented. Can be stably implemented.
Also, as compared with the conventional case where a continuous casting mold is manufactured by combining thermal spraying and plating, the short side member can be manufactured only by thermal spraying, so that the manufacturing process can be shortened and simplified. Thus, productivity can be improved and manufacturing cost can be reduced.

And since the hardness of the thermal spray layer of the long side member contact surface of the short side member is smaller than the hardness of the plating layer formed on the inside facing surface of the pair of long side members, for example, the inside facing of the pair of long side members When the short side member moves on the surface, damage to the plating layer can be reduced, and the life of the mold can be extended.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1A is a plan view of a continuous casting mold according to an embodiment of the present invention, FIG. 1B is a partially enlarged explanatory view of the inside of the dotted line in FIG. Partial enlarged plan views of the continuous casting mold, FIGS. 3A to 3E are explanatory views of the method for manufacturing the continuous casting mold according to one embodiment of the present invention.

As shown in FIGS. 1 (A) and 1 (B), a continuous casting mold (hereinafter also simply referred to as a mold) 10 according to an embodiment of the present invention is disposed to face each other with a distance D, and is moved by movement. A pair of short-side members (also referred to as narrow cooling members or short piece members) 11 and 12 capable of adjusting the distance D, and a pair of long-side members (wide cooling members) arranged to face each other with the short-side members 11 and 12 interposed therebetween (Also referred to as long piece members) 13 and 14, and molten steel is poured into a space 15 formed by the pair of short side members 11 and 12 and the pair of long side members 13 and 14, and solidified to produce a slab. In this case, the molten steel contact surface 16 and the long-side member contact surface 17 of the short-side members 11 and 12 are provided with a sprayed layer 18 that maintains a right angle of the angle in plan view. Since the pair of short side members 11 and 12 have substantially the same configuration, the short side member 12 will be described in detail below.

The short side member 12 has, for example, a cooling plate 19 made of copper or a copper alloy having a thickness of 30 mm or more and 50 mm or less. A water guide groove is formed, and a stainless steel back plate (not shown) is attached to the back surface thereof.
The sprayed layer (hereinafter also referred to as a molten steel side sprayed layer) 20 formed on the molten steel contact surface side which is the surface side of the cooling plate 19 has a thickness T1 of, for example, 0.3 mm to 1.5 mm. The sprayed layer (hereinafter also referred to as a long-side member-side sprayed layer) 21 formed on the long-side member side of the cooling plate 19 has a thickness T2 of, for example, 0.3 mm to 2.5 mm (here 1 mm). ing.
The molten steel side end surface 22 of the long side member side sprayed layer 21 is covered with the molten steel side sprayed layer 20.

The molten steel side sprayed layer 20 is, for example, Cr: 0 or more than 0 and 18% by mass or less, B: 1.0% by mass to 4.5% by mass, Si: 1.5% by mass to 5.0% by mass C: 1.1 mass% or less, Fe: 5.0 mass% or less, Co: 1.0 mass% or less, Mo: 4.0 mass% or less, Cu: 4.0 mass% or less, and balance Ni It is made of a Ni-based self-fluxing alloy.
Further, the hardness of the long-side member-side sprayed layer 21 is, for example, Hv10 from the hardness (for example, about Hv200) of the Ni plating layer 23 formed on the inner (surface side) facing surface of the pair of long-side members 13 and 14. Above (preferably Hv30 or more, more preferably Hv50 or more) is small. Examples of the thermal spray material capable of obtaining such hardness include Ni: 5 mass% to 30 mass%, Si: 1.0 mass % to 4.0 mass%, and B: 0.5 mass% to 3. There is a Cu-based self-fluxing alloy (for example, about Hv180) such as 0% by mass or less and the balance Cu. Since this Cu-based self-fluxing alloy has better thermal conductivity than the Ni plating layer, the heat removal at the corners inside the mold 10 is also improved.

In addition, it is preferable to add a cermet to the molten steel side sprayed layer and the long side member side sprayed layer, using the above-mentioned alloy as a matrix. Here, as the wear-resistant hard ceramic constituting the cermet, for example, any one or more of carbide, oxide, boride, nitride, and silicide can be used.
The molten steel side sprayed layer and the long side member side sprayed layer can be formed by spraying directly on the surface of the cooling plate, but are formed by spraying on the cooling plate through a plating layer of Ni or an alloy mainly composed of Ni. It is also possible.
As shown in FIG. 2, the long-side member-side end surface 25 of the molten steel-side sprayed layer 24 formed on the cooling plate 19 can be covered with the long-side member-side sprayed layer 26.
In this case, since the end surface 27 of the long-side member-side sprayed layer 26 comes into contact with the molten steel, there is a possibility that partial wear due to the molten steel occurs. For this reason, it is preferable that the hardness of the molten steel side sprayed layer 24 and the long-side member-side sprayed layer 26 is set to the same level as the hardness of the molten steel side sprayed layer 20.

When using the mold 10, the pair of short side members 11, 12 is centered on the center in the longitudinal direction of the pair of long side members 13, 14 in order to adjust the distance D according to the size of the slab to be manufactured. Are moved in line symmetry, so that the ends of the short side members 11 and 12 are worn out. For this reason, the reduced portion of the width of the short side member is regenerated by thermal spraying. As this method, it is possible to perform thermal spraying from above without cutting the worn part at the end of the short side member. However, as in the case of forming a conventional plating layer, the side surface of the cooling plate and the thermal spray layer After cutting from the boundary portion to the cooling plate side, for example, by about 1 mm or less (preferably 0.5 mm or less), thermal spraying can also be performed.
In this way, the worn part generated at the end of the short side member can be regenerated by thermal spraying, and the short side member can be restored, so there is no need to perform plating as in the conventional case, and the work process can be shortened and simplified. Can be planned.

Next, a method for manufacturing a continuous casting mold according to an embodiment of the present invention will be described with reference to FIGS. 1 and 3A to 3E.
First, as shown in FIG. 3A, a cooling plate 19 constituting the short side member 12 (the same applies to the short side member 11) is prepared, and as shown in FIG. 3B, both end faces of the cooling plate 19 are prepared. The above-described Cu-based self-fluxing alloy is sprayed on the long-side member contact surface side to form the temporary long-side member-side sprayed film 28.
Next, as shown in FIG. 3C, the above-described Ni-based self-fluxing alloy is sprayed on the surface of the cooling plate 19 on which the temporary long-side member-side sprayed film 28 is formed in contact with the molten steel, A temporary molten steel side sprayed film 29 is formed.
Thereby, the end surface 30 on the molten steel side of the temporary long side member-side sprayed film 28 is covered with the temporary molten steel-side sprayed film 29.

In addition, after reversing the order of the thermal spraying shown in FIG. 3 (B) and FIG. 3 (C), after forming the temporary molten steel side sprayed film on the surface of the cooling plate 19 on the contact side with the molten steel, It is also possible to form a temporary long-side member-side sprayed film on both end surfaces (long-side member contact surface side). When the short side member is manufactured by this method, as shown in FIG. 2, the end surface 27 of the long side member-side sprayed layer 26 is in contact with the molten steel, so that the molten steel side sprayed layer 24 and the long side member-side sprayed layer 26 are configured. For example, the same Ni-based self-fluxing alloy is preferably used as the thermal spraying material.
In addition, when regenerating the reduced width of the used short side member 12, the worn portion is ground smoothly as necessary, and the cooling plate side is also separated from the boundary between the side surface of the cooling plate and the sprayed layer. After grinding, the thermal spraying is performed from above to restore the short side member.

Then, as shown in FIG. 3 (D), Ni-based self-fluxing alloy is further sprayed onto the end face 31 of the provisional molten steel side sprayed film 29, and supplementary spraying is applied to the sprayed shortage portion at the end of the provisional molten steel side sprayed film 29. Layer 32 is formed. This supplementary sprayed layer may not be formed according to the thickness of the sprayed layer 18.
After forming the temporary sprayed layer 33 (comprised of the temporary long-side member-side sprayed film 28, the temporary sprayed steel-side sprayed film 29, and the supplementary sprayed layer 32) on the cooling plate 19, the sprayed layer 33 is heated to 900 ° C. or higher and 1100 ° C. Heat treatment (fusing) is performed below (here, 980 ° C.). This heat treatment is preferably performed in an oxygen-free atmosphere or in an inert atmosphere filled with nitrogen gas, for example, for about 10 minutes to 30 minutes. The method is preferably performed in a furnace using a heating furnace from the viewpoint of uniform mold quality, but can also be performed using, for example, a burner or a laser.
Thus, by performing heat processing at 900 degreeC or more, while performing the solution treatment of a cooling plate, the fusion | melting process of a sprayed layer is performed and the adhesive force to the cooling plate of a sprayed film improves. On the other hand, the heat treatment is set to 1100 ° C. or lower because the melting point of the sprayed film is about 1100 ° C.

The temporary sprayed layer 33 formed on the portion excluding the back surface side of the cooling plate 19 by the above method is cut (ground) at the position indicated by the one-dot chain line in FIG. Long-side member-side sprayed layers 21 having a thickness T2 are formed. Thus, the thermal spraying layer 18 which made the angle | corner a right angle can be formed by machining.
As shown in FIG. 1B, the long-side member is plated with Ni or Co on the surface of the cooling plate 34 which is a surface where the pair of long-side members 13 and 14 face when the mold 10 is formed. Layer 23 is formed and manufactured.

After attaching a back plate to the back side of the cooling plates 19 and 34 of the pair of short side members 11 and 12 and the pair of long side members 13 and 14, as shown in FIGS. The short-side members 11 and 12 are opposed to each other with a distance D, and the pair of long-side members 13 and 14 are arranged with the short-side members 11 and 12 sandwiched therebetween, and a continuous casting mold 10 having a space 15. Manufacturing. In addition, formation of the water guide groove to each cooling plate of the short side member and the long side member is performed in advance before the back plate is attached.
When using this mold 10, depending on the shape of the slab to be manufactured, the pair of short side members 11, 12 are moved symmetrically about the center in the longitudinal direction of the pair of long side members 13, 14 After adjusting the distance D, the molten steel is poured into the space 15 and solidified to produce a slab.
From the above, as in the prior art, for example, without performing a plating process for protecting the end face of the short side member, and without performing a welding process for restoring the worn part at the end of the short side member, Since the short side member can be manufactured, the manufacturing process can be shortened and simplified.

As described above, the present invention has been described with reference to one embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and is described in the claims. Other embodiments and modifications conceivable within the scope of the above are also included. For example, the case where the continuous casting mold of the present invention and the manufacturing method thereof are configured by combining some or all of the above-described embodiments and modifications are also included in the scope of the present invention.
Further, the material of the sprayed layer is not limited to those described in the above embodiment, and can be appropriately selected according to casting conditions (for example, molten steel temperature or casting speed).

(A) is a top view of the casting mold for continuous casting according to an embodiment of the present invention, and (B) is an explanatory view in which the inside of the dotted line in (A) is partially enlarged. It is the elements on larger scale of the continuous casting mold which concerns on a modification. (A)-(E) are explanatory drawings of the manufacturing method of the casting mold for continuous casting which concerns on one embodiment of this invention. (A) is a top view of the casting mold for continuous casting according to the conventional example, (B) is an explanatory view partially enlarged in the dotted line of (A).

10: mold for continuous casting, 11, 12: short side member, 13, 14: long side member, 15: space, 16: molten steel contact surface, 17: long side member contact surface, 18: sprayed layer, 19: cooling plate 20, 21: sprayed layer, 22: molten steel side end surface, 23: plated layer, 24: molten steel side sprayed layer, 25: long side member side end surface, 26: long side member side sprayed layer, 27: end surface, 28: temporary Long side member side sprayed film, 29: Temporary steel side sprayed film, 30, 31: End face, 32: Supplementary sprayed layer, 33: Temporary sprayed layer, 34: Cooling plate

Claims (2)

A pair of short side members that are arranged to be opposed to each other with a gap and movable, and a pair of long side members that are sandwiched between the short side members, and the pair of short side members and the pair of long side members In a continuous casting mold for producing a slab by pouring molten steel into a space formed by and solidifying, a plating layer is formed on the inner facing surface of the pair of long side members, and the long side member is in contact with the long side member A thermal spray layer is formed on the long side member contact surface of the short side member, and the hardness of the thermal spray layer of the long side member contact surface is higher than the hardness of the plating layer formed on the inner facing surface of the pair of long side members. A continuous casting mold characterized by its small size. 2. The continuous casting mold according to claim 1, wherein the plating layer formed on the inner facing surface of the long side member is a Ni plating layer, and the thermal spray material forming the thermal spray layer is Ni: 5 mass% or more and 30%. Continuous casting, characterized in that it is a self-fluxing alloy comprising: mass% or less, Si: 1.0 mass % or more and 4.0 mass% or less, B: 0.5 mass% or more and 3.0 mass% or less, and the balance Cu. Mold.

Images