JPH0229428B2 - SHINZAINOKYOJINNAFUKUGOROORUNOSEIZOHOHO - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing a composite roll having a strong core material. (Prior art) In rolling rolls, the surface of the roll body that comes into contact with the rolled material is generally coated with wear-resistant, crack-resistant,
Surface roughness resistance is required, while the core is required to have the toughness to withstand rolling loads, so the outer shell layer of the body is made of high-alloy grain material, high-alloy chilled material, high-alloy ductile cast iron material, etc. It is made of a high-alloy cast iron material with high hardness carbide inside, while the core and neck part are usually made of a composite material made of a strong material such as low-alloy high-grade cast iron or ductile cast iron in consideration of economic efficiency. rolls are being used. However, with recent changes in rolling conditions, there is a tendency to increase the rolling reduction ratio and to roll low-temperature materials, and for this reason, the core material that forms the body core and neck portion needs to be stronger. However, in the case of work rolls for hot stripping, it is necessary to increase the rigidity of the core material to reduce deformation of the roll, so the core material has an elastic modulus. It is desired to use a material with a large value. In order to meet these demands, the applicant has proposed a composite roll in which the core material is made of stronger cast steel, graphite cast steel, or adamite (see Utility Model Application Nos. 170075 to 170077). (Problem to be Solved by the Invention) However, when forming the core material from such a strong material, while the outer shell layer is formed from a cast iron material with a relatively low melting point, The melting point of the core material is higher than that of the outer shell layer material, and therefore it is necessary to raise the casting temperature, which causes the following problems in manufacturing. In other words, when casting this type of composite roll, after casting the outer shell layer according to the normal centrifugal casting method, when the molten core material is cast to be welded and integrated with the outer shell layer, the melting of the outer shell layer material Since the temperature of the core material molten metal is considerably high compared to the temperature, not only the amount of erosion on the inner surface of the outer shell layer increases, but also the thickness (a + b)
The problem is that a considerably thick portion b on the inner surface side of the outer shell layer 1 is reheated by the high-temperature core material 3, and a portion is formed in which the carbides in the outer shell layer cast iron structure become graphitized. To explain this more specifically, when the core material is also made of cast iron material for the cast iron material that forms the outer shell layer, the casting temperature of the core material is 1300 to 1400°C; The thickness of the graphitized portion b on the inner surface of the layer is approximately 3 to 7 mm. However, when the core material is cast steel, the casting temperature is 1400 to 1550℃.
The thickness of the graphitized part b is 10~
It reaches 20mm, and as a result, the effective use layer a of the outer shell layer
The wall thickness becomes that much thinner. In this way, as a core material, cast steel materials with low C content, graphite cast steel materials, or adamite materials,
Particularly in the case of composite rolls that use a material that is tough and has a higher melting point than the outer shell material, a thick graphitized part with poor wear resistance inevitably occurs on the inner surface of the outer shell layer during casting. There is a problem in that it is difficult to obtain a roll with a particularly thick outer shell layer because the effective usable layer decreases and at the same time, the amount of erosion on the inner surface of the outer shell layer increases. (Means for Solving the Problems) The method for manufacturing a composite roll with a strong core material according to the present invention, which has been made in order to solve the above-mentioned problems, includes high-alloy grain material, high-alloy chilled material, high-alloy ductile cast iron material, etc. The outer shell layer is centrifugally cast using a high-alloy cast iron material that has highly hard carbides in its structure and has a melting point of around 1150℃, and after the outer shell layer solidifies, the C content is added to its inner surface.
An intermediate layer material made of cast iron such as high-grade cast iron or ductile cast iron containing 2.5 to 3.7% by weight is centrifugally cast, the inner surface of the outer shell layer is remelted, the intermediate layer is welded and integrated, and cast steel is applied to the inner surface of the intermediate layer. , graphite cast steel, adamite materials, etc.
The structure of the invention is to weld and integrate the core material onto the inner surface of the intermediate layer by casting a material having a melting point of 1300° C. or higher. (Function) The outer shell layer is centrifugally cast, and after solidification of the outer shell layer, an intermediate layer made of cast iron with a C content of 2.5 to 3.7% by weight is centrifugally cast on the inner surface. It is less likely to be eroded by the molten metal of the intermediate layer material, and further reduces the eroding damage of the inner surface of the outer shell layer due to casting of the intermediate layer, compared to when the molten metal of the intermediate layer material is cast when the inner surface of the outer shell layer is not yet solidified. be able to. The C content of the intermediate layer cast iron material is 2.5 to 3.7% by weight.
The reason for specifying this is that within this range, the melting point is comparable to that of the outer shell layer material, and therefore the casting temperature does not need to be raised, which contributes to preventing melting damage on the inner surface of the outer shell layer.
That is, if C is less than 2.5%, the melting point of the intermediate layer will be high, and the casting temperature will inevitably also be high, making it impossible to meet the technical purpose of the present invention. On the other hand, if the C content exceeds 3.7%, the melting point is low, which is advantageous from the viewpoint of casting temperature, but it lacks toughness from the viewpoint of a roll material and is not suitable from the viewpoint of roll function. Because it will disappear. The other alloy components of the material used for the intermediate layer do not have as great an effect on the melting point, but the alloy components and their content may be adjusted as appropriate from the viewpoint of hardness and strength as a roll material. be adjusted. When the intermediate layer is welded and integrated with the inner surface of the outer shell layer and a high melting point core material such as cast steel is cast into the inner surface, the core material melts the inner surface of the intermediate layer and reduces the thickness of the intermediate layer, but the outer shell layer Since the inner surface is not directly damaged by melting, it is possible to significantly reduce melting damage and graphitization of the outer shell layer due to casting of the core material. That is, the intermediate layer acts as a buffer zone against erosion and graphitization of the inner surface of the outer shell layer during casting of the core material. (Example) To carry out the present invention, first, a high-alloy cast iron material having the required properties as a layer used in a rolling roll is cast into a centrifugal casting mold, and an outer shell layer is placed on the inner surface of the mold using centrifugal force. to cast. Centrifugal force casting methods include horizontal type,
It is applicable to both inclined type and rigid type. As the outer shell layer material, the following high-alloy grain material, chilled material, or ductile material containing 2.5 to 3.7% by weight of C is usually used. In addition to the components listed below, special components such as Ti, V, Nb, and W may also be included, but in any case, the C content is 2.5 to 3.7.
%, has high hardness carbide in the structure, 1150
It typically has a melting point around ℃. Outer shell layer composition (wt%, remainder substantially Fe) High alloy grain material C: 2.5 to 3.7%, Si: 0.5 to 1.2%, Mn: 0.4 to 1.0%, P: less than 0.15%, S: 0.1% Ni: 2.0 to 5.0%, Cr: 1.0 to 2.5%, Mo: 0.1 to 1.0% B High alloy chilled material C: 2.5 to 3.7%, Si: 0.1 to 0.7%, Mn: 0.1 to 0.6%, P: Less than 0.5%, S: less than 0.1%, Ni: 2.0 to 5.0%, Cr: 0.5 to 1.2%, Mo: 0.1 to 1.0% C High alloy ductile material C: 3.0 to 3.7%, Si: 1.0 to 2.0%, Mn : 0.2 to 1.0%, P: less than 0.1%, S: less than 0.015%, Ni: 2.0 to 5.0%, Cr: 0.3 to 1.0%, Mo: 0.1 to 1.0% Mg: 0.03 to 0.08% Next, the outer shell layer After solidifying, a cast iron material such as high-grade cast iron or low-alloy ductile cast iron with a C content of 2.5 to 3.7% by weight is cast on the inner surface, and an intermediate layer is centrifugally cast on the inner surface of the outer shell layer. This intermediate layer is for preventing the core material molten metal from coming into direct contact with the inner surface of the outer shell layer and causing melt damage and graphitization during casting of the core material, which will be described later. By casting the intermediate layer, as shown in Figure 3,
A portion (T ₃ ) of the inner surface of the outer shell layer (casting thickness T ₁ ) is remelted and melted into the molten intermediate layer material to form a new intermediate layer (thickness T ₄ ). In the diagram, a ₁ is the final (product)
The thickness of the outer shell layer 1, T ₂ is the casting thickness of the intermediate layer. A preferred composition example of the new intermediate layer when high-grade cast iron or ductile cast iron is used as the intermediate layer material is shown below. New intermediate layer composition (wt%, remainder substantially Fe) High-grade cast iron C: 2.5-3.7%, Si: 0.8-1.5%, Mn: 0.4-1.0%, P: less than 0.3%, S: less than 0.1%, Ni: 0.2-3.0%, Cr: 1.0-1.5%, Mo: 0.1-0.5% Ductile cast iron C: 2.5-3.7%, Si: 1.0-2.0%, Mn: 0.2-1.0%, P: less than 0.3%, S: less than 0.1%, Ni: 0.2-3.0%, Cr: 0.1-1.5%, Mo: 0.1-0.5% Mg: 0.01-0.08% Next, toughness is determined when all or most of the new intermediate layer has solidified. A core material made of cast steel or cast iron with excellent properties is cast. Specific examples of the core material include cast steel, graphite steel, or adamite material with a low C content, as described below. Their melting point is usually 1300℃
The casting temperature is 1400 to 1500°C. Cast iron material C: 0.4-1.1wt% Graphite steel material C: 1.0-2.2wt% Adamite material C: 1.0-2.5wt% By casting the core material, a new intermediate layer (thickness T ₄ ) is created as shown in Figure 3. The inner surface (thickness T ₅ ) is remelted by the molten core material, or when the inner surface of the new intermediate layer is unsolidified, it directly melts into the molten core material, and this is solidified to form the product core material 3. In the figure, C is the thickness of the final intermediate layer 2. Note that the composition of the final intermediate layer is the same as that of the new intermediate layer. Examples of suitable compositions for the product core material are shown below. The composition below provides not only the toughness in the core but also the wear resistance required for the bearing part of the neck part. Core material composition (weight%, remainder substantially Fe) A Cast steel material C: 0.4 to 1.1%, Si: 0.1 to 1.5%, Mn: 0.1 to 1.5%, P: less than 0.05%, S: less than 0.03%, Ni : 0.01~1.5%, Cr: 0.01~1.5%, Mo: 0.01~1.0% B Graphite steel C: 1.0~2.2%, Si: 1.0~2.0%, Mn: 0.1~1.5%, P: less than 0.05%, S : Less than 0.03%, Ni: 0.01-1.5%, Cr: 0.01-1.0%, Mo: 0.01-1.0% C Adamite material C: 1.0-2.5%, Si: 0.1-1.5%, Mn: 0.1-1.5%, P : less than 0.05%, S: less than 0.03%, Ni: 0.01 to 1.5%, Cr: 0.3 to 2.0%, Mo: 0.01 to 1.0% In the above manner, as shown in FIG. A composite roll is manufactured in which three layers, the (final) intermediate layer 2 and the (product) core material 3, are welded and integrated. Here, the casting thicknesses of the outer shell layer and the intermediate layer of the composite roll having the above three-layer structure will be described. The casting thickness of the outer shell layer is determined, of course, by the intended thickness of one side of the roll. That is, it is determined by taking into consideration the machining allowance for the shell surface, the erosion loss allowance for the inner surface due to the molten metal cast as the intermediate layer, and a slight margin necessary for the thickness of one wall. On the other hand, when determining the casting thickness of the intermediate layer, there is a limit to the difference between the body diameter and the neck diameter for roll products, so from this point of view, the casting thickness of the intermediate layer can be determined by rolling. There is an upper limit due to the shape, and on the other hand, if the amount of the middle layer molten metal is too small, the temperature of the molten metal in the ladle will drop significantly, which will hinder work, so there is a lower limit to the casting thickness. It must be kept in mind that there are practical limits to this.
In addition, the casting thickness may be appropriately selected within the above-mentioned practical limits depending on the material forming the outer shell layer and the combination conditions with the core material. Since the purpose is to reduce the unfavorable thermal influence on the outer shell layer due to molten metal casting, it is not necessary to make it too thin. Considering these conditions comprehensively, for rolls with normal shapes and dimensions,
The appropriate casting thickness of the intermediate layer is T ₂ =15 to 80 mm. In this case, the casting weight of the intermediate layer material is 200Kg.
Approximately 2 tons is sufficient, and when the core material is directly cast (for medium to large rolls, the amount reaches approximately 10 to 15 tons).
Its heat capacity is much smaller than that of the outer shell layer, and even if part of the inner surface of the outer shell layer is remelted by casting the middle layer, the temperature of the cast middle layer itself will drop rapidly. The majority of the wall thickness other than the inner surface side is not significantly affected by heat. Also, if the erosion loss on the inner surface of the outer shell layer is approximately T ₃ = 3 to 15 mm, the thickness of the new intermediate layer newly formed by welding with the outer shell layer is T ₄ = 18 to 15 mm. If the thickness is 95 mm, and if the corrosion loss due to core casting is estimated to be T ₅ =15 to 40 mm, the final intermediate layer thickness in the as-cast product will be C = 3 to 55 mm. Next, specific examples of the present invention are listed below. Example 1 A composite roll having a body size of 600φ×2057 mm was manufactured using the following casting components and casting conditions for the outer shell layer, intermediate layer, and core material. The middle layer molten metal was cast immediately after the outer shell layer had solidified (the same applies to the following examples).

【table】

[Table] In this composite roll, the inner surface of the outer shell layer is 10mm
was remelted into the molten intermediate layer and mixed with the molten intermediate layer to form a new 40 mm thick intermediate layer with the following components:

[Front] This new intermediate layer is made of core material that has a thickness of 15 to 15 mm on the inner surface.
With 20 mm melted away, the final intermediate layer thickness in the as-cast product was 20-25 mm. The thickness of the graphitized portion on the inner surface of the outer shell layer was 4 to 5 mm, and a composite roll having a thick outer shell layer as an effective usable layer was obtained. Example 2 A composite roll having the same dimensions as Example 1 was manufactured using the following casting components and casting conditions.

【table】

[Table] In this composite roll, the inner surface of the outer shell layer is approximately 13
mm was remelted into the intermediate layer molten metal and mixed with the intermediate layer molten metal to form a new intermediate layer with a thickness of 43 mm with the following components:

[Front] This new intermediate layer has an inner surface of 19~19 mm due to core material casting.
With 25 mm melted away, the final intermediate layer thickness in the as-cast product was 18-24 mm. The thickness of the graphitized portion on the inner surface of the outer shell layer was 5 to 6 mm, and a composite roll having a thick outer shell layer as an effective usable layer was obtained. Example 3 A composite roll having the same dimensions as in Example 1 was manufactured using the following casting components and casting conditions.

【table】

[Table] In this composite roll, the inner surface of the outer shell layer is 10mm
was remelted into the molten intermediate layer and mixed with the molten intermediate layer to form a new 40 mm thick intermediate layer with the following components:

[Front] This new intermediate layer is made of core material that has been cast into an inner surface of 25~25mm
With 30 mm melted away, the final intermediate layer thickness in the as-cast product was 10-15 mm. In this case, since the core material was cast steel, the casting temperature was high and the amount of erosion in the intermediate layer was large. The thickness of the graphitized part on the inner surface of the outer shell layer was also slightly larger at 6 to 10 mm, but it was much less than when no intermediate layer was provided, and the composite roll has a sufficiently thick outer shell layer for effective use. was gotten. Example 4 A composite roll having the same dimensions as Example 1 was manufactured using the following casting components and casting conditions.

【table】

[Table] In this composite roll, the inner surface of the outer shell layer is 15mm
was remelted into the molten intermediate layer and mixed with the molten intermediate layer to form a new 45 mm thick intermediate layer with the following components:

[Front] This new intermediate layer is made of core material that has a thickness of 10 to 10 mm on the inner surface.
After 15 mm was melted away, the final intermediate layer thickness in the as-cast product was 30-35 mm. In this case, the core material is adamite material and the casting temperature is lower than in other examples, so there is less heat influence, and the thickness of the graphitized part on the inner surface of the outer shell layer is about 5 mm, so the thick outer shell has an effective usable layer. A composite roll with layers was obtained. In the above examples, we mainly talked about the casting conditions and chemical composition, but when the manufactured composite roll is commercialized, after rough processing, it is subjected to strain relief heat treatment or heat treatment at 900 to 1000℃ to improve the toughness of the core material. Subjected to high temperature heat treatment. In this case, in order to maintain the wear resistance of the outer shell layer, a step of normalizing or isothermal transformation heat treatment to transform the base structure into a bainite or martensitic structure may be included. In addition to the above-mentioned examples, preferable materials for the outer shell layer, intermediate layer, and core material of the composite roll according to the present invention may be any combination of the following specific examples depending on the purpose. can be done. Outer shell layer: High alloy grain material, high alloy chilled material, high alloy ductile cast iron material Middle layer: High grade cast iron material, ductile cast iron material Core material: Cast iron material, graphite steel material, Adamite material (effects of the invention) As explained above, According to the method for manufacturing a composite roll of the present invention, the outer shell layer is centrifugally cast using a high alloy cast iron material such as a high alloy grain material, and after solidification of the outer shell layer, the inner surface of the cast iron is coated with a C content of 2.5 to 3.7%. The intermediate layer material made of wood is centrifugally cast, the inner surface of the outer shell layer is remelted, and the intermediate layer is welded and integrated, so the inner surface of the outer shell layer is less likely to melt or become graphitized, and furthermore, the inner surface of the outer shell layer is not left unfinished. Compared to the case where the intermediate layer material is cast during solidification, melting damage on the inner surface of the outer shell layer due to the casting of the intermediate layer material can be further reduced. Furthermore, since a high melting point core material such as cast steel is cast into the inner surface of the intermediate layer after forming the intermediate layer, the intermediate layer acts as a buffer zone and the outer shell Erosion damage and graphitization due to the core material on the inner surface of the layer can be significantly reduced, and a thick effective layer in which highly hard carbide is present in the outer shell layer can be easily obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the structure of a composite roll according to the present invention. FIG. 2 is a cross-sectional explanatory diagram for comparison, showing the problems when high-temperature core molten metal is directly cast into the inner surface of the outer shell layer. FIG. 3 is an explanatory cross-sectional view showing variations in thickness of the composite roll outer shell layer and intermediate layer according to the present invention. 1... Outer shell layer, 2... Middle layer, 3... Core material.

Claims (1)

[Claims] 1 The outer shell layer is centrifugally cast using high-alloy cast iron materials such as high-alloy grain materials, high-alloy chilled materials, and high-alloy ductile cast iron materials that have high hardness carbides in their structures and have a melting point of around 1150℃. After solidifying the shell layer, an intermediate layer material made of cast iron material such as high-grade cast iron or ductile cast iron with a C content of 2.5 to 3.7% by weight is centrifugally cast on the inner surface of the shell layer, and the inner surface of the outer shell layer is remelted to form the intermediate layer. A core characterized in that a material having a melting point of 1300°C or higher, such as cast steel, graphite cast steel, or adamite material, is cast onto the inner surface of the intermediate layer, and a core material is integrally welded onto the inner surface of the intermediate layer. A method of manufacturing a composite roll made of strong materials.