JPS6099493A - Production of clad plate - Google Patents

Abstract

PURPOSE:To obtain a three-layered clad plate having good adhesiveness and corrosion resistance by inserting, by casting, the metallic plate joined via a release agent into the 2nd metal, blooming the plate and separating the plates from the joined part, hot-rolling the separated plate, further inserting, by casting, the separated plate into the 3rd metal and rolling the plate. CONSTITUTION:Two sheets of the 1st metallic plates 1 consisting of Ni, etc. are joined to each over via a release agent 5 and are suspended in a casting mold 3. The 2nd metal 2 such as stainless steel or the like is cast into the mold to insert the 1st plates 1 by casting into said metal. The cast ingot consisting of two kinds of such metallic layers are subjected to soaking and blooming and are separated to two parts from the agent 5 part. The two billets are hot-rolled to form clad metallic plates. After the surfaces of two sheets of the clad plates 7 are cleaned, the plates are symmetrically suspended in the mold 3 and the 3rd metal such as molten cast steel or the like is cast between the two plates 7 to obtain the cast ingot consisting of at least three kinds of the metallic layers. Such cast ingot is subjected to soaking, blooming and cutting by which the clad plate having a desired size is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a clad plate comprising two metal layers on each side of a base metal.

More specifically, the present invention relates to a method of manufacturing a clad plate having two metal layers on both sides that have good adhesion to the base metal.

Conventional and ■ Clad materials are inexpensive, long-life steel materials with corrosion resistance and strength, which are made by bonding a relatively expensive dissimilar metal with corrosion resistance to an inexpensive base metal. expensive.

Various methods are commonly known for producing cladding materials, such as crimping, explosion bonding, welding, and casting.

Various types of cladding materials are manufactured that are composed of two types of metal layers, or three or more types of metal layers. By the way, when manufacturing these clad materials, a particular problem is the adhesive strength between the base material and the laminated material.

The first factor that affects adhesive strength is the diffusion and transfer of carbon from the base metal into the laminated material due to hot working or heat treatment during or after the manufacture of the cladding material. This is because when the base material is carbon steel and the bonding material is stainless steel, the problem of carbon diffusion migration cannot be ignored because there is a difference in bonding affinity between Fe-C and Cr-C. As carbon diffuses and transfers from the base metal to the laminated material, a carburized layer is formed near the interface of the laminated material, which embrittles the interface and reduces adhesiveness. Furthermore, the formation of a carburized layer reduces the effective thickness of the laminated material and also reduces the corrosion resistance function of the laminated material.

Furthermore, as carbon diffuses and transfers from the base metal into the laminated material, elements in the laminated material, such as Cr, and carbon diffused from the base metal combine and precipitate as carbides. This leads to product defects, which not only reduces the adhesion between the base metal and the composite material, but also reduces the extensibility of the cladding material itself, resulting in poor formability.

Another problem with the cladding material is peeling due to poor adhesion caused by manufacturing conditions between the base metal and the composite material. For example, when dissimilar metal plates are bonded together by rolling, depending on conditions such as the cleanliness of the bonding surfaces, rolling pressure, rolling temperature, etc., poor adhesion may occur and peeling may occur.

Furthermore, in the welding method, the surface may be oxidized due to the surrounding oxidizing atmosphere during welding in the atmosphere, or adhesion failure may occur due to slag being involved during welding.

Furthermore, in the casting method, which is carried out to reduce adhesion defects in rolling and welding methods, the interface where the metal plate to be cast and the molten metal come into contact may be affected by poor cleanliness on the surface of the metal plate or in the molten metal. Adhesion is not necessarily good due to the capture of floating scum, etc.

In view of the above-mentioned defects of the cladding material, an example of a method for manufacturing a clad steel plate composed of multiple layers by a casting method is described in JP-A-57-121853 and JP-A-56-26666. has been done.

The method described in JP-A-57-121853 is as follows:
After forming a thin layer by plating or spraying Cr, Nb, Mo, V, etc. on the surface of the laminated material, NN is applied on the thin layer.
4 This is a method in which a borofluoride such as BF4, KBF4 or NaBF+ is applied, and then the laminated material is poured and poured with molten metal. In this method, borofluoride is vaporized just before the laminate material and molten metal come into contact with each other, thereby preventing scum from being drawn in and improving adhesion. On the other hand, the presence of a thin layer sprayed or plated on the surface of the laminated material can prevent the diffusion of carbon from the base metal into the laminated material. There is a limit to its effectiveness, and if the thickness is increased, the adhesive quality remains questionable and costs increase.

The method described in Japanese Patent Application Laid-open No. 56-26666 involves separating metal plates of the same type or different types, the surfaces of which are coated with evaporable metals such as Ca and Mg, from each other in a mold, and
This method involves placing the metal plate away from the inner wall of the mold and casting it with molten metal, but due to the presence of evaporable metals such as Ca and Mg coated on the surface of the metal plate and the distance of the metal plate from the inner wall of the mold, Although adhesion is improved, since the metal layers formed are one on each side of the base metal, diffusion of carbon from the base metal into the laminated material cannot be prevented.

Furthermore, it is possible to manufacture a cladding material consisting of two layers by rolling or welding the laminating material in advance, and then casting it in molten metal to manufacture a cladding material consisting of three layers. Since the adhesive is rolled or welded in advance, poor adhesion cannot be sufficiently resolved, making the process complicated and impractical.

It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a method for manufacturing a clad plate made of at least three types of metal layers that has excellent corrosion resistance and does not peel off. .

More particularly, it is an object of the present invention to provide a process by which clad plates containing at least three metal layers that are well adhered to each other can be produced economically and in large quantities.

As a result of many years of experimentation and research, the inventors of the present invention have found that the basic technique of conventional technology, which involves applying an intermediate metal layer by conventional thermal spraying or plating, then casting with another metal layer, and rolling this. Defects and their causes are clarified.

In other words, the cast metal layer and the sprayed or plated metal layer cannot maintain an appropriate layer thickness ratio as a result of subsequent rolling.
Therefore, the effect of interposing the intermediate metal layer in the finished clad plate is lost.

In order to solve this problem, the present inventors propose to manufacture all metal layers by casting when manufacturing a clad plate with an appropriate layer thickness ratio in consideration of thickness reduction due to rolling.

Therefore, according to the present invention, in the method for manufacturing a clad plate comprising at least two types of metal layers on both sides of a base metal layer, two first metal plates are bonded via a release agent, and this bonding The clad metal plate is cast into a second metal to produce a clad ingot having the second metal on both sides, and after the clad ingot is bloomed, it is divided from the part of the release agent in the center. Two layers of cladding metal layers are each obtained, the cladding metal pieces are hot-rolled to form two cladding metal plates, and the two cladding metal plates are arranged symmetrically inside the mold. , a third metal is cast into the space Q between them to form a three-layer clad ingot consisting of three types of metal layers,
There is provided a method for producing a cladding plate comprising at least two types of metal layers on each side of a base metal by rolling the 3N cladding ingot.

Here, the release agent applied to the two first metal plates is a 5i02 series refractory, etc., which can be easily divided into two by driving a wedge or the like by cutting the end of the clad ingot after rolling it. Similarly, it is preferable to join two metal plates by temporarily welding the ends of the metal plates so that the ingot after rolling can be easily divided into two parts. preferable.

According to a preferred embodiment of the invention, the base metal 4 is common steel, the first metal is Ni-Nokel, and the second metal forming the outer layer of the finished clad plate is stainless steel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1-3 are schematic diagrams illustrating the steps of an example embodiment of the present invention.

First, the composition shown in Table 1 that forms the intermediate layer has dimensions of 30
A stripping agent 5 such as 5i02 refractory is applied to the surface of two first metal Ni metal plates 1 with a thickness of 750 mm at a layer thickness of about 3
After coating and overlapping, the periphery is tack welded to join. After that, N1148F4, KBF 4, or N1148F4, KBF4, or N1148F4, KBF4, or N
Apply a borofluoride such as aBF4.

Next, the joined first metal plates 1 are suspended in a mold 3 by a support plate 4 as shown in FIG. By under-pouring, the casting speed is 500 mm/min to 1000 m.
m/min at a casting temperature of 1600°C to form the first metal plate 1.
is coated with a second metal 2.

In this case, as shown in FIGS. 1 and 2, the first metal]
The purpose of forming the coating layer 6 containing borofluoride on the surface of the F6 steel sheet is to decompose the borofluoride with the heat of the molten steel and generate gas immediately before the metal plate 1 and the molten steel 2 come into contact with each other. This is to prevent floating scum from being captured on the adhesive surface. If scum is captured, it will naturally cause poor adhesion.

The reason for setting the casting speed to 500 mm/min to 1000 mm/min is that if it is slower than 500 mm/min, the borofluoride-containing layer 52 will be heated by the molten metal before the metal plate and the molten metal surface come into contact. This is because when the first metal plate I comes into contact with the hot water surface due to vaporization, sufficient gas is not generated and scum is trapped on the adhesive surface. If the speed is too slow than 1000 mm/min, the borofluoride will not be completely vaporized and will remain on the adhesive surface, causing poor adhesion and inclusion defects.

Next, the cast dimensions are 800mm thick x 800mm1i
After soaking the ingot made of two types of metal layers in J, it was rolled by blooming rolling and the top and bottom parts were cut off, and then a wedge was driven into the part coated with release agent 5 to divide it into two parts. Two pieces of slab. The two obtained slabs are hot rolled at a rolling temperature of about 1300° C. to produce a clad metal plate having second metal layers on both sides.

The two manufactured clad metal plates 7 are each 40 mm thick.
Thickness x 750 mm 1 l], the surface was cleaned by descaling pickling, coated with borofluoride, and suspended symmetrically inside the mold 3 by a support plate 4 as shown in FIG. Between them is a third base metal having the composition shown in Table 1.
of metal, i.e. carbon steel molten steel 8, is poured by pouring 500
Cast at a speed of mm/min to 1000 mm/min and a casting temperature of 1480°C.

In this case, the purpose of cleaning the surfaces of the two clad metal plates 7 suspended in the mold and applying borofluoride is the same as when casting the first metal 1 with the second metal 2. .

When two metals 7 are symmetrically suspended in the mold 3, 2
It is necessary that each of the sheets be 10 mm to 5 Q mm away from the mold wall surface. This is the metal 7 suspended within the mold 3.
When the metal plate 7 comes into close contact with the inner wall surface of the mold, the metal 7 becomes integrated with the mold and acts as a part of the mold wall, so a gap is created between the solidified molten metal 8 and the metal plate 7, and oxygen is absorbed into this part. is supplied, resulting in poor adhesion. If the gap 9 between the mold wall surface and the metal plate 7 is 10 mm or less, it will be difficult for the molten metal 8 to enter.
Moreover, if it is 50 mm or more, this portion will be cut and removed after producing the ingot, resulting in a decrease in yield.

The reason why the casting speed is set to 500 mm/min to 1000 mm/min is the same as the case where the first metal 1 is poured with the second metal 2.

The dimensions of the three metal layers obtained in this way were 80 mm.
A three-layer clad ingot with a thickness of 0 mm and a width of 800 mm is soaked, bloomed into desired dimensions, and cut in the longitudinal direction of the ingot using a slab cutter. At this stage, the portion where the mold wall surface and the metal plate 7 were close to each other is cut away until the surface of the metal plate 7 is exposed. After that, it was hot rolled at a rolling temperature of 1300°C to provide two types of metal layers on both sides of the base metal, and the layer thickness ratio of stainless steel, Ni, and base metal was 40:3:4, respectively.
EXAMPLE 1 A 20 mm thick x 1800 mm rll clad plate made of 00 was manufactured.

A three-layer rad plate product with two types of metal layers on each side of the base metal manufactured by the method shown in the above-mentioned example was found to have no defects such as inclusion defects on the adhesive surface in the UST flaw detection test. Defects are rarely seen, and the results of microstructural observation using a microscope show that carbon diffusion is blocked by the Ni layer interposed between the laminated material and the base material, and almost no carburized layer is formed in the stainless steel. It had not been done.

As detailed above, the method of the present invention prevents the diffusion of carbon from the base material into the bonding material, which is an inherent problem with cladding materials, and achieves excellent corrosion resistance and good adhesion that can eliminate bonding defects. Can be secured.

[Brief explanation of the drawing]

1 to 3 are schematic diagrams illustrating the steps of a method according to an embodiment of the present invention, in which FIG. 1 shows a cross section of a clad ingot made of first and second metals in a casting condition; Figure 2 shows its horizontal cross section, and Figure 3 does not show the cross section of the third metal, that is, molten steel, being poured between the 2N clad plates. 1. Ni metal plate 2. Stainless steel molten steel 3. Mold 4. Support plate 5. Release agent 6. Coating layer (borofluoride) 7. Stainless steel + Ni metal plate 8. Carbon steel molten steel Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney Kazuhiko Arai Figure 1 Figure 2

Claims (1)

[Claims] In a method for manufacturing a clad plate comprising at least two types of metal layers on both sides of a base metal, two first metal plates are bonded via a release agent, and the bonded metal plate is bonded to a second metal plate. A clad ingot having a second metal layer on both sides is cast, and after the clad ingot is bloomed and rolled, it is divided into two layers of clad metal pieces from the peeling material part in the center. The clad metal piece was hot-rolled to make a two-layer clad metal plate, and the above two layers were placed inside the mold.
Layers of clad metal plates are arranged symmetrically, a third metal is cast into the space between them to cast a three-layer clad ingot consisting of three types of metal layers, and the three-layer clad ingot is cast. A method for manufacturing a clad plate comprising at least two metal layers on each side of a base metal by rolling.