JPS61286044A - Continuous casting method for clad slabs - Google Patents

Abstract

PURPOSE:To prevent sticking of coating slag onto the surface of a solid material to be fed into a casting mold and to make possible the satisfactory joining of a molten metal and the non-limitation of an outside dimension by heating the surface of the solid material to the temp. at which said material can be metallurgically joined to the other molten material. CONSTITUTION:The solid material 4 which is continuously fed into the casting mold 1 is heated by a heater 3 to the temp. at which the surface thereof can be metallurgically joined to the other material 13 in a molten state. The metallic molecules of both materials intersect consequently with each other at the joint boundary and since the surface of the material 4 is heated to a high temp., the sticking of the coating slag to the surface thereof is obviated. As a result, an alloy layer 12 having excellent affinity is formed at the intermediate of both metallic compsns. of the other material (base metal) 13 and the solid material (cladding metal) 11. The base metal 13 and the cladding metal 11 are securely joined in the clad ingot 10 produced in the above-mentioned manner and therefore these metals do not peel even if the two metals have the considerably different coeffts. of expansion. The material supplied in the solid state is therefore hot limited in the outside dimension.

Description

[Detailed Description of the Invention] "Objective of the Invention" (Industrial Field of Application) The metal material includes a base material of an inexpensive ordinary material having a desired strength, and a base material for the chemical industry, the atomic crab industry, and the marine industry. 9. There is a clad metal material that is integrally bonded with a special material laminate that has been used in the food industry, etc. 0. The present invention is based on continuous casting of a clad slab, which is the raw material for the above-mentioned clad metal material. Relating to a method of manufacturing. It is something.

(Conventional continuous casting method) Conventionally, a belt-shaped composite material made of a special material is fed into the mold of continuous casting equipment, and molten metal to be a base material of a different material from the composite material is fed into the mold. There is a method of manufacturing clad slabs by injection. For example, JP-A-51-111458
The technical content described in the 0M first application publication is one example.
As shown in the figure, a band-shaped laminate made of a corrosion-resistant material, D, is fed along the inner wall of the long side of the mold A according to the casting speed, and a tundish B is placed in the remaining inner space of the mold A. Melting &
The purpose is to manufacture a crushed slab in which a corrosive resistant material and a base material of ordinary steel are joined by injecting and pulling out IC. In other words, one side of the room-temperature laminate material, D, which is fed into the mold A, is slightly melted by the heat of the high-temperature molten steel, and the laminate material, D, and molten GK
C are welded together.

(The problem that the invention attempts to solve) In the technique of the prior application publication, the laminated material is laminated at room temperature.

In order to make the welding between D and molten steel C complete and strong, the molten steel must be a room-temperature laminate to be welded.

Heat must be distributed to D to raise the temperature of its surface above the melting temperature. Therefore, the casting temperature of molten steel C must be kept quite high. Moreover, it takes a certain amount of heat transfer time for the surface of the room-temperature laminate D to melt due to contact with the molten C. This heat transfer time becomes longer with the increase in heat capacity symbolized by the thickness of the laminate D, and the casting speed is also inevitably retarded.

The thickness of D is accompanied by 1jJIa. Also, if the casting temperature of molten steel C is made higher in order to shorten the heat transfer time, the time required for solidification will increase, so in this case as well, the casting speed will be delayed and the casting This leads to a decrease in efficiency. As described above, the technology disclosed in the prior application contradicts the requirement of having a strong bonded state and the requirement of improving casting efficiency, making it extremely difficult to implement the technology from an operational point of view. Ta.

By the way, generally the molten wiC+ injected into mold A
A covering slag is formed floating on the upper surface.

The purpose of the coating slag is to absorb impurities and non-metallic inclusions floating from the molten steel, prevent heat dissipation from the top surface of the molten steel CI, and provide lubrication between the mold A and the slab Z. Therefore, it is extremely important for continuous casting.

However, as mentioned above, the temperature of the laminated material D is raised only when it comes into contact with the molten C1, so when it comes into contact with the coating slag, it is still at room temperature plus the ambient temperature. It's just that. Laminated material with low surface temperature.

Naturally, coating slag tends to adhere to D,
Laminating material, D,! : Non-metallic inclusions of the coating slag are mixed into the joint with the melt & IC+, resulting in the formation of an unhealthy segregation layer. Therefore, even though the laminate material D and the base material C obtained by solidifying the molten steel CI appear to be temporarily welded to each other, a strong bond has not been reached. Such an unhealthy and brittle joint state is particularly serious when there is a significant difference between the linear expansion coefficient of the laminate D and that of the base material C1! During the cooling process, the shearing force due to the shrinkage difference between the laminate D and the base metal C acts on the bonding interface between the laminate D and the base material C.
This had a serious drawback in that the parts 8 and 8 would peel off.

Especially in continuous casting equipment where the drawing form is curved,
When pulling out a clad slab made of two layers of laminated material D and the base material, and subsequently straightening it, tensile stress acts on one layer between the two and causes stress on the other layer. Since compressive stress acts, the shearing force is further amplified, making it difficult to avoid the occurrence of peeling between the two. These fatal defects become more serious as the cross-sectional area of the laminate increases.

Additionally, the technique disclosed in the earlier application can be implemented when the laminated material D is solid at room temperature and the base material C1 is supplied in a molten state, but in the opposite case, it is almost impossible to implement it. It's impossible.

The present invention has been made in view of the above-mentioned circumstances. Firstly, even when using a laminate material that is solid at room temperature, the thickness is not limited, and secondly, the coating slag is suspended in the mold. Even if the bonding interface between the bonding material and the base material is mixed with non-metallic inclusions, an unhealthy segregation layer will not be generated, and thirdly, the base material is solid at room temperature and the bonding material is supplied in a molten state. The continuous casting method (hereinafter referred to as the "Continuous Casting Method") is a method that can be carried out even in cases where the cladding material and the base material are firmly joined, so there is no risk of peeling, and that clad slabs can be manufactured with high efficiency. ).

"Structure of the Invention" (Means for Solving the Problems) The gist of the present continuous casting method is to continuously inject one of the base material and the laminate material, which are of different materials, into a mold in a solid state. When producing a clad slab in which the two are joined by continuously injecting the other in a molten state between the inner wall of the mold and the solid material, the solid material fed into the mold. The method is to heat the surface of the molten pool to a temperature at which it can be metallurgically bonded to the molten pool material.

(Function) The solid material fed into the mold is heated to a temperature at which its surface can be metallurgically bonded to other companies in a molten state.
Regardless of whether either the base material or the laminate is in a solid state or the other is in a molten state, the metal molecules of both will cross each other at the bonding interface, and the surface of the solid material will be at a high temperature, so Since coating slag does not adhere, a layer of non-metallic inclusions is not generated at the bonding interface, and an alloy layer with excellent affinity for the metal composition of the base material and laminate is formed. Become. As described above, in the clad slab manufactured by the present continuous casting method, the base metal and the laminated metal are strongly bonded, so even if the coefficients of linear expansion of the respective metals are significantly different, However, no peeling occurs during the shrinking process. Of course, no peeling occurs even in continuous casting equipment where the drawing form is curved. Therefore,
In the present continuous casting method, there are no restrictions on the external dimensions of the material supplied in a solid state, regardless of whether it is used as a laminate or as a base material. In addition, since the surface of the solid material fed into the mold is heated, the amount of heat transfer from the molten metal to the solid material and the heat transfer time are reduced, making it possible to increase the casting speed. There is.

(Example) The present invention will be described below based on drawings showing examples thereof.

FIG. 1 is a front sectional view schematically showing the present continuous casting method.

In this embodiment, a strip-shaped solid 4 to be made of a special material laminate 11 is continuously fed along one side of the inner wall in the mold 1, while a molten metal to be made to be a base material 13 made of a normal material is fed continuously. 5
is continuously injected into the mold 1 from the tundish 2, and the clad slab 10 in which the cladding material 11 and the base material 13 are integrally joined via the alloy layer 12 is pulled out from the mold 1. be.

The most distinctive method of this embodiment is to heat the surface of the band-shaped solid material 4 for the cladding material fed into the mold 1 to a temperature at which it can be metallurgically bonded to the molten metal 5 for the base material. be. Here, the metallurgical joining of the strip-shaped solid material 4 and the molten metal 5 means that an alloy layer 12 in which mutual metal molecules are mixed is formed at the joint portion of the strip-shaped solid material 4 and the molten metal 5, and this alloy layer 12 has an excellent affinity for both the laminating material 11 and the base material 13, and the temperature at which metallurgical bonding is possible means that the metal molecules of the band-shaped solid material 4 and the molten metal 5 This refers to the temperature at which the metal molecules in the band can move between each other.When looking at the band-shaped solid material 4, the range of solidus temperature to liquidus temperature (hereinafter referred to as melting temperature) of the metal or alloy constituting it is the temperature at which the metal molecules of temperature range).

In other words, in order to achieve a metallurgical bond, at least the bonding surface of the band-shaped solid material 4 with the molten metal 5 must be melted.

Basically, the higher the temperature when heating the surface of the band-shaped solid material 4, the better. This is to prevent the coating slag floatingly formed on the upper surface of the molten metal 5 in the mold 1 from adhering to the surface of the band-shaped solid material 4. But in reality,
It is determined based on the relationship between the melting temperature range of the band-shaped solid material 4 and the casting temperature of the molten metal 5.

Here, let us consider a case where the casting temperature of the molten metal 5 is higher than the melting temperature range of the band-shaped solid material 4. In other words,
Since the molten metal 5 is maintained in a state sufficient to distribute its own heat to the band-shaped solid material 4 and melt its surface, the heating temperature at this time is equal to the surface of the band-shaped solid material 4. The temperature may be set with consideration given to shortening the heat transfer time until 4a reaches the melting temperature range as much as possible. Specifically, it is slightly lower than the melting temperature range of the band-shaped solid material 4.

Therefore, the band-shaped solid material 4 is heated and melted by coming into contact with the molten metal 5, and after the band-shaped solid material 4 and the molten metal 5 are metallurgically joined, the molten metal 5 is heated by the cooling action received from the mold 1. coagulates with the coagulation of

Also, in contrast to the above case, consider a case where the melting temperature range of the band-shaped solid material 4 is higher than the casting temperature of the molten metal 5. That is, not only cannot the band-shaped solid material 4 be expected to receive heat from the molten metal 5, but also the heat of the band-shaped solid material 4 is released toward the molten metal 5, and sometimes receives a cooling effect. Conceivable. Therefore, the heating temperature at this time is
Before the strip-shaped solid material 4 is fed into the mold 1, it is necessary to ensure that the temperature reaches the melting temperature range or higher. However, if the band-shaped solid material 4 is melted too much, the alloy layer 12 with the molten metal 5 may become thicker than necessary, making it impossible to maintain a predetermined cladding ratio. It is desirable to keep the melting temperature slightly higher than the melting temperature range.

Further, the bonding surface 4 of the band-shaped solid material 4 with the molten metal 5
It is also possible to heat only a to a temperature higher than the melting temperature range. Therefore, the band-shaped solid material 4 begins to cool and solidify from the moment it comes into contact with the molten metal 5, and is metallurgically joined at the joint portion with the molten metal IE5.

As shown in FIG. 1, in this embodiment, the band-shaped solid material 4 was heated at a position directly above the mold 1 using a heating device 3 consisting of a high-frequency induction coil. However, as mentioned above (in the case where only the joining surface 4a of the band-shaped solid material 4 with the molten metal 5 is heated),
Heating may be performed using a gas burner (not shown) or the like, or heating may be performed by directly applying electricity to the band-shaped solid material 4.

Note that the reference numeral 6 in the figure indicates an electromagnetic stirring device. The electromagnetic stirring device 6 is embedded so as to surround the inside of the mold 1, and homogenizes the composition and temperature of the molten metal 5.
This is intended to promote metallurgical bonding with the melted surface of the band-shaped solid material 4 and prevent the occurrence of peeling and the like. In addition, when the linear expansion coefficient of the strip-shaped solid material 4 and the linear expansion coefficient of the molten metal 50 are approximate, for example, the material of the molten metal 5 serving as the base material 13 is general structural carbon steel such as 5S41, and the laminated material is 1
When the material of the band-shaped solid material 1 is special-purpose carbon steel, ferritic stainless steel, etc., the electromagnetic stirring device 6 can be omitted.

As described above, the band-shaped solid material 4 and the molten gold Wk5 are completely metallurgically joined, and the molten metal 5 gradually solidifies starting from the layer closest to the inner wall of the mold 1. At the stage of being pulled out from the mold 1, even if an unsolidified portion remains in the core, the band-shaped solid material 4 becomes the laminate material 11, the molten metal 5 becomes the base material 13, and the two are integrated through the alloy layer 12. This results in a clad slab 10 that is symmetrically joined.

The present inventor manufactured a clad slab by the present continuous casting method, and specific numerical values regarding the manufacturing conditions at that time are shown in Fragrances 1 to 4 in the table below.

In addition, a comparative example in which the band-shaped solid material was not heated was manufactured using a band-shaped solid material similar to the above-mentioned fragrances 1 to 4, so the specific numerical values regarding this comparative example are shown in the same table. It is also listed in fragrances 5 to 8.

As is clear from the table below, the clad slab produced by the continuous casting method has an incomparably strong bonding strength compared to the case where the solid strip material is not heated, based on the data on "interfacial shear strength". I can see that

On the other hand, in Comparative Examples, especially in perfumed slabs 5 and 7, peeling already occurred when they were pulled out as slabs, and some of them were not able to be manufactured into cracked slabs in the first place. Furthermore, when comparing the casting speed between the continuous casting method of the present invention and that of the comparative example, it can be seen that the continuous casting method of the present invention can achieve manufacturing efficiency that is more than twice that of the comparative example. Furthermore, in the present continuous casting method, by heating the strip-shaped solid material, the temperature of the molten metal can be kept as low as possible, which results in a faster time for the molten metal to cool and solidify. table>
Although not described in , the inventor of the present invention feeds two strips of solid material to be made of a special material along two opposing walls of a mold, and inserts a strip of ordinary material between the two strips of solid material. We have also succeeded in manufacturing double-sided clad slabs by injecting molten metal to serve as the base material. In addition, contrary to the above embodiment, when a clad slab is manufactured by feeding a base material made of a normal material as a solid strip and injecting a material made of a special material in a molten state. was also carried out. In other words, while feeding a thick strip-shaped solid material to the center of the mold to serve as the base material, molten metal is injected into each gap between the opposing surfaces of the thick strip-shaped solid material and the inner wall of the mold to form a double-sided clad slab. Manufacture.

Note that the method of the present invention can also be applied to the production of cast slabs for clad metal materials made of non-ferrous metals other than steel materials. Furthermore, the solid material may be of any shape other than a strip, such as a bar or a tube.In addition, in the manufacturing method shown in FIG. 1, the inner surface of the solid material (4), that is, the molten metal By heating only the side surface in contact with the solid material (4), it is possible to replace the solid material (4) as a mold, and it is also possible to omit one side of the mold.

(The following is a blank space) Continued on the next page "Effects of the Invention" As is clear from the above explanation, according to the method for continuous casting of clad slabs according to the present invention, the surface temperature of the solid material to be the clad material or the base material By being heated, the coating slag is prevented from adhering to the surface of the solid material, good metallurgical bonding with the molten metal, unlimited external dimensions of the base material and clad slab, streamlining of casting speed, It has become possible to suppress the temperature of molten steel. Of course, the clad slab produced by this continuous casting method has a good alloy layer formed at the joint between the special metal and the ordinary metal, which has an affinity for each of the materials, so there is no possibility of peeling. etc. will never occur.

[Brief explanation of drawings]

Figure 1 is a front sectional view schematically showing the continuous casting method in question;
FIG. 2 is a schematic sectional view showing the technical content described in the prior application publication. 1...Mold 2...Tandish 3.
... Heating device 4 ... Band-shaped solid material 5 ... Molten metal 7 ... Electromagnetic stirring device 10 ... Clad slab 11 ... Lamination material 12 ... Alloy 1iii13
...Base material patent applicant Sumitomo Kinku Kogyo Co., Ltd. Representative Patent attorney 1) Toshihiko Figure 2

Claims (1)

[Claims] 1. Continuously feeding one of the base material and laminate material, which are of different materials, into the mold in a solid state, and continuously feeding the other in a molten state between the inner wall of the mold and the solid material. A cladding characterized by heating the surface of the solid material fed into the mold to a temperature at which it can be metallurgically joined to another molten material when producing a clad slab in which both are bonded by injection. Continuous casting method for slabs.