JPH1161322A - Rolling roll outer layer material and rolling roll using the material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling roll outer layer material and a rolling roll using the material which has a low friction coefficient, is excellent in heat crack resistance, seizure resistance and skin roughening resistance while maintaining wear resistance and is capable of realizing quality improvement of a rolled product and high productivity of rolling work. SOLUTION: The rolling roll outer layer material has a composition consisting of, by weight, 1.5-3.0% C, 0.2-3.0% Si, 0.2-2.0% Mn, 7.0-20.0% Cr, <=6.0% Mo, <=6.0% W, <=6.0% V and the balance essentially Fe with inevitable impurities, further having a M7 C3 type eutectic carbide as well as a carbide area in the structure, which satisfies M7 C3 >=(M2 C+M6 C+MC)×3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling roll outer layer material and a rolling roll using the same.

[0002]

2. Description of the Related Art A roll material for hot rolling is required to have abrasion resistance, surface roughness resistance, and accident resistance (crack resistance).
Alternatively, as disclosed in JP-A-1-96355
A high-speed roll material containing Cr, Mo, W, V, Co, etc., each containing several weight% is known. Since this high-speed roll material has good abrasion resistance at high temperatures, it is suitable as an outer layer material for forming a use layer of a composite roll. Further, as a manufacturing technique of the high-speed composite roll, a composite continuous casting method, a centrifugal casting method, a powder HIP method, and the like are known.

However, since the conventional high-speed roll material has a structure mainly composed of very hard MC type carbide in order to improve wear resistance, the difference in hardness between the MC type carbide and the base during use is large. As a result, the base is worn preferentially, and as a result, carbides protrude, and there is a problem in that roughening is likely to occur due to an increase in wear coefficient, deterioration of seizure resistance, or lack of protruding carbides.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems of the conventional high-speed roll material, and has a low friction coefficient and a low heat resistance for hot rolling while maintaining good wear resistance. It is an object of the present invention to provide a roll outer layer material which is excellent in cracking property, seizure resistance, and surface roughening resistance, can improve the quality of a rolled product and realize high productivity of a rolling operation, and a roll for roll using the same. .

[0005]

In order to solve the above-mentioned problems, an outer layer material for a rolling roll according to the present invention comprises 1.5 to 3.0% by weight of C, 0.2 to 3.0% by weight of Si, 0.2 to 2.0% by weight of Mn,
7.0 to 20.0% by weight of Cr, 6.0% by weight or less of Mo, 6.0% by weight of W
Wt% or less, the V contained 6.0 wt% or less, the balance being a chemical composition consisting essentially of Fe and disabled impurities, mainly M ₇
Together with a C ₃ -type eutectic carbides, carbide area in the tissue is first characterized in that the _{M 7 C 3 ≧ (M 2} C + M 6 C + MC) × 3. Further, the outer layer material of the roll for rolling of the present invention has C
1.5 to 4.0% by weight, 0.2 to 3.0% by weight of Si, 0.2% of Mn
~ 2.0 wt%, Cr 7.0 ~ 20.0 wt%, Ni 1.5 ~ 6.0
Wt%, Mo 6.0% or less, W 6.0% or less, V
6.0% by weight or less, the balance being substantially composed of Fe and non-impurities, and having a chemical composition obtained by adding a spheroidizing element of graphite, and having a carbide area in the structure of M ₇ C ₃ ≧ (M ₂ C +
The second feature is that M ₆ C + MC) × 3 and spherical graphite is crystallized in the structure. On the other hand, the roll for rolling according to the present invention is obtained by welding a molten steel of an outer layer material having a chemical composition shown in the first feature or the second feature and having a microstructure to a steel-based core material by a continuous casting method. The third feature is that they are integrated. Further, the rolling roll of the present invention, the molten metal of the outer layer material having the chemical composition shown in the first feature or the second feature and having a microstructure, and the molten inner layer material of ductile cast iron or graphite steel, The fourth feature is that they are integrated by welding by a centrifugal casting method.

In the roll outer layer material having the first feature, the content of C is 1.5 to 3.0% by weight. C
Combines with Cr, Mo, W, and V to form high hardness carbides (M ₇ C
₃ type, M ₂ C type, M ₆ C type, MC type etc.) to increase the abrasion resistance of the roll. If the content is less than 1.5% by weight, the amount of carbide generated is insufficient, and the wear resistance during hot operation is insufficient. On the other hand, if it exceeds 3.0% by weight, the amount of carbide is too large,
Decreases toughness and heat crack resistance.

[0007] The content of Si is 0.2 to 3.0% by weight. Si
Has the effect of improving the deoxidation of the molten metal and the castability. If it is less than 0.2% by weight, the effect is insufficient, while if it exceeds 3.0% by weight, toughness and mechanical properties are deteriorated.

The content of Mn is 0.2 to 2.0% by weight. Mn
Has an effect of deoxidizing the molten metal. If the content is less than 0.2% by weight, a sufficient effect cannot be obtained, and if it exceeds 2.0% by weight, the toughness of the material decreases, which is not preferable.

The content of Cr is 7.0 to 20.0% by weight. Cr
Combines with C to form a high hardness M ₇ C ₃ type eutectic carbide,
It has the effect of increasing wear resistance and toughness. In addition, a part is dissolved in the base to strengthen the base. On the other hand, in conventional high-speed roll materials, MC type carbides are mainly used, whereas M ₇ C ₃
By mainly using type carbide, the friction coefficient has been reduced and the surface roughness resistance has been successfully improved. However, the Cr content is 7.
If the amount is less than 0% by weight, these effects are insufficient, and if it exceeds 20.0% by weight, the carbide becomes coarse and the amount thereof becomes excessive, and the toughness and the heat crack resistance deteriorate. When the carbide area ratio in the structure is set to M ₇ C ₃ ≧ (M ₂ C + M ₆ C + MC) × 3, the friction coefficient is low as a hot rolling roll,
It is important for improving the heat crack resistance, the seizure resistance and the rough surface resistance.

The content of Mo is set to 6.0% by weight or less including zero. Mo dissolves in the base, improves the hardenability,
In addition to improving the high-temperature softening resistance, it has the effect of forming a high-hardness double carbide such as M ₂ C-type carbide and M ₆ C-type carbide by combining with C to improve the wear resistance during hot working. However, if the content exceeds 6.0% by weight, coarse M ₂ C-type carbides increase, leading to a decrease in toughness.

The content of W is set to 6.0% by weight or less including zero. W forms a solid solution in the matrix to increase tempering softening resistance and heat resistance, and combines with C to form a high-hardness double carbide such as M ₂ C type or M ₆ C type, thereby improving wear resistance. Improve. However, when the content exceeds 6.0% by weight, carbides are coarsened and segregation tends to occur during production.

The content of V is set to 6.0% by weight or less including zero. V combines with C to form a hardened MC-type carbide most effective for improving wear resistance. However, if it exceeds 6.0% by weight, the abrasion resistance is improved, but the improvement of the rough surface resistance, which is the object of the present invention, cannot be achieved.

The roll outer layer material having the second characteristic is a material having excellent seizure resistance by crystallizing graphite in the structure, but the content of C is 1.5 to 4.0% by weight. . C binds Cr, Mo, W, is V, the high hardness of the carbide (M ₇ C ₃ type, M ₂ C type, M ₆ C-type, MC type) or alone to form a graphite resistance of the roll Increases abrasion and seizure resistance.
If the content is less than 1.5% by weight, the amount of carbide and graphite formed is insufficient, the wear resistance during hot operation is insufficient, and the seizure resistance is not improved. On the other hand, if it exceeds 4.0% by weight, the amount of carbides increases and the toughness decreases.

The Ni content is 1.5-6.0% by weight. Ni
Is an element necessary for crystallizing graphite in the structure, and has an effect of improving hardenability. Its content
If the content is less than 1.5% by weight, these effects are insufficient, while 6.
If it exceeds 0% by weight, an unstable structure such as the presence of retained austenite is formed.

The components of Si, Mn, Cr, Mo, W, and V are the same as the conditions of the components in the first feature. In the second feature, the carbide area ratio in the structure is M ₇ C ₃ ≧ (M ₂ C + M ₆ C + MC) × 3,
The condition is that spheroidal graphite cast iron is crystallized in the structure. By the spheroidal graphite being appropriately crystallized in the structure,
It becomes a roll outer layer material for rolling with a lower coefficient of friction and excellent seizure resistance.

In the outer layer material according to the second feature,
By adjusting the contents of C, Si, and Ni, graphite is crystallized in the structure. By further adding a spheroidizing element of graphite, the graphite to be crystallized is made into spherical graphite. As the spheroidizing element of graphite to be added, for example, two or one of Ca and Mg is used, and by adding the element to, for example, a molten metal, spheroidal graphite is crystallized in the structure. Although the addition amount of Ca and Mg may be small, an amount suitable for spheroidizing the crystallized graphite and having no other undesired effects is obtained in advance by experiments.

The rolling roll according to the third aspect of the present invention is characterized in that the rolling roll has a first or second roll relative to the steel core material.
A roll for rolling can be obtained by welding and integrating the molten metal of the outer layer material having the characteristic of (1) by a continuous casting method of continuously casting the outer periphery of the steel core material.

The rolling roll according to the fourth aspect of the present invention is characterized in that the melt of the outer layer material having the first or second aspect is first subjected to centrifugal casting, and then the inner layer of ductile cast iron or graphite steel having high toughness is formed. The roll of the roll can be obtained by putting the molten metal of the material inside the outer layer material, centrifugally casting and welding and integrating them. Further, the roll material manufactured as described above, quenching for texture and hardness adjustment,
A tempering treatment and an annealing treatment for removing residual stress and stabilizing the structure are performed to obtain a roll for rolling according to required characteristics.
Rolling roll outer layer material and rolling roll of the present invention, in addition to wire rod rolling, finishing work roll for hot rolling,
The present invention can be applied to any roll used in a hot state, such as a roll for strip steel rolling and a roll for steel pipe.

[0019]

Examples Examples of the roll outer layer material according to the first feature of the present invention were produced as No. 1 and No. 2. The chemical composition is shown in Table 1. Although the chemical composition condition according to the first feature is satisfied, the carbide area is M ₇ C ₃ ≧ (M ₂ C + M ₆ C + MC)
Those that were out of the condition of × 3 were melted as Comparative Examples No. 3 to No. 5. The chemical composition is shown in Table 1. Further, conventional high-speed materials were melted as conventional examples No. 6 to No. 9. The chemical composition is shown in Table 1. Similarly, Examples of the roll outer layer material according to the second feature of the present invention were produced as No. 10 and No. 11. Table 2 shows the chemical composition. Although the chemical composition condition according to the second feature is satisfied, the carbide area is
What has become a condition outside of _{M 7 C 3 ≧ (M 2} C + M 6 C + MC) × 3, was melted as Comparative Examples No.12 ~ No.14. Table 2 shows the chemical composition. Further, conventional high-speed materials were melted as No. 15 to No. 17 in the conventional example. Table 2 shows the chemical composition.
Shown in In Tables 1 and 2, the underlined component values and the like indicate that the values are out of the range of the components in the present invention.

[0020]

[Table 1]

[0021]

[Table 2]

Each roll outer layer material is subjected to a heat treatment (1000-1200 ° C.) for structure adjustment, hardness adjustment and residual stress removal.
Quenching and tempering at 500-600 ° C)
Was given.

As an evaluation of each of these outer layer materials, the Shore hardness was measured, the area ratio of carbide was measured, and a friction and wear test was performed.
A burn-in test was performed. Table 3 shows the results. In the measurement of the area ratio of the carbide, the area ratio for each carbide form was measured by EPMA surface analysis and image analysis (in the case of graphite crystallization, the area ratio of graphite was also measured). In the friction and wear test, the friction coefficient and the wear loss were measured under the following conditions.
In the seizure test, the seizure load and the seizure torque were measured by the following Falex method. [Friction wear test] Test method: Pin-on-disk method Test piece temperature: 300 ° C Load: 5 kg / cm ² Rotational speed: 100 m / min Sliding distance: 20000 m [Seizure test] Test method: Falex method (K- F type seizure test machine) Test piece size: φ10 (φ6.5) × 32L Counterpart material (V block): SUS304 Rotation speed: 284rpm

[0024]

[Table 3]

In Examples No. 1 and No. 2 of the roll outer layer material according to the first feature of the present invention, as is clear from Table 3, Comparative Examples No. 3 to No. compared to example Nanba6～nanba9, although somewhat abrasion loss is large and tends seen with M ₇ C ₃ type carbide is increased, there is the friction coefficient is low tendency and seizure resistance is improved Is obtained. From the results shown in Table 3, Examples No. 1 and No. 2 have the effect of considerably improving the problems of the rough surface resistance and the seizure resistance of the conventional high-speed roll material (conventional examples No. 6 to No. 9). We can expect that there is. An actual roll was manufactured using a material considered to be optimal among the outer roll materials for the rolling rolls of Examples No. 1 and No. 2, and a rolling test was performed using this roll for a wire rod intermediate stand. As a result, we succeeded in obtaining the desired satin-like rolled skin.

In Examples No. 10 and No. 11 of the roll outer layer material according to the second feature of the present invention, as is apparent from Table 3, Comparative Examples No. 12 to No. Example No.15
Compared with No.17, the amount of graphite increased in proportion to the increase in Ni content (although there was a relationship with the Si content), and graphite was spheroidized by the addition of Ca and Mg. . And it became clear that the coefficient of friction tends to decrease and the seizure resistance improves with the crystallization amount. Examples
An actual machine roll was manufactured using the material considered to be optimum from the outer roll materials of the No. 10 and No. 11 rolling rolls, and this was actually used as a vertical roll for H-section steel, and a rolling test was actually performed. As a result, compared to conventional high speed rolls, there is no seizure,
Demonstrated good results.

[0027]

According to the roll outer layer material for hot rolling according to the first aspect, while maintaining good wear resistance and heat crack resistance in hot rolling, very good rough surface resistance is exhibited. It is possible to reduce the coefficient of friction and improve seizure resistance. Therefore, it is possible to improve the quality of the rolled product and realize high productivity of the rolling operation. In addition, according to the roll outer layer material of claim 2, by including Ni, crystallized graphite can be obtained in the structure, and the graphite is spheroidized by the addition of a spheroidizing element. Therefore, it is possible to provide a roll for rolling that has reduced friction coefficient and excellent seizure resistance and heat crack resistance while maintaining good wear resistance in hot rolling. Therefore, it is possible to improve the quality of the rolled product and realize high productivity of the rolling operation. Claim 3
According to the rolling roll described in the above, while maintaining abrasion resistance and heat crack resistance, it is possible to exhibit very good surface roughness resistance, reduce the friction coefficient, and improve seizure resistance. be able to. Therefore, it is also possible to improve the quality of the rolled product and achieve high productivity of the rolling operation. According to the rolling roll of the fourth aspect, while maintaining good wear resistance in hot rolling, the friction coefficient can be reduced, and seizure resistance and heat crack resistance can be improved. . Therefore, it is also possible to improve the quality of the rolled product and achieve high productivity of the rolling operation.

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[Procedure amendment]

[Submission date] September 11, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Rolling roll outer layer material and rolling roll using the same

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling roll outer layer material and a rolling roll using the same.

[0002]

2. Description of the Related Art A roll material for hot rolling is required to have abrasion resistance, surface roughness resistance, and accident resistance (crack resistance).
Alternatively, as disclosed in JP-A-1-96355
A high-speed roll material containing Cr, Mo, W, V, Co, etc., each containing several weight% is known. Since this high-speed roll material has good abrasion resistance at high temperatures, it is suitable as an outer layer material for forming a use layer of a composite roll .

However, since the conventional high-speed roll material has a structure mainly composed of very hard MC type carbide in order to improve wear resistance, the difference in hardness between the MC type carbide and the base during use is large. As a result, the base is worn preferentially, and as a result, carbides protrude, and there is a problem in that roughening is likely to occur due to an increase in wear coefficient, deterioration of seizure resistance, or lack of protruding carbides.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems of the conventional high-speed roll material, and has a low friction coefficient and a low heat resistance for hot rolling while maintaining good wear resistance. It is an object of the present invention to provide a roll outer layer material which is excellent in cracking property, seizure resistance, and surface roughening resistance, can improve the quality of a rolled product and realize high productivity of a rolling operation, and a roll for roll using the same. .

[0005]

In order to solve the above-mentioned problems, an outer layer material for a rolling roll according to the present invention comprises 1.5 to 3.0% by weight of C, 0.2 to 3.0% by weight of Si, 0.2 to 2.0% by weight of Mn,
7.0 to 20.0% by weight of Cr, 6.0% by weight or less of Mo, 6.0% by weight of W
Wt% or less, the V contained 6.0 wt% or less, the balance being a chemical composition consisting essentially of Fe and disabled impurities, mainly M ₇
Together with a C ₃ -type eutectic carbides, carbide area in the tissue is first characterized in that the _{M 7 C 3 ≧ (M 2} C + M 6 C + MC) × 3. Further, the outer layer material of the roll for rolling of the present invention has C
1.5 to 4.0% by weight, 0.2 to 3.0% by weight of Si, 0.2% of Mn
~ 2.0 wt%, Cr 7.0 ~ 20.0 wt%, Ni 1.5 ~ 6.0
Wt%, Mo 6.0% or less, W 6.0% or less, V
6.0% by weight or less, the balance being substantially composed of Fe and non-impurities, and having a chemical composition obtained by adding a spheroidizing element of graphite, and having a carbide area in the structure of M ₇ C ₃ ≧ (M ₂ C +
The second feature is that M ₆ C + MC) × 3 and spherical graphite is crystallized in the structure. On the other hand, the rolling roll of the present invention, the molten metal of the outer layer material to be and organizational structure has a chemical composition shown in the first aspect or the second aspect, and a steel-based core material is integrated soluble adhesive Is a third feature. Further, the rolling roll of the present invention, the molten metal of the outer layer material having the chemical composition shown in the first feature or the second feature and having a microstructure, and the molten inner layer material of ductile cast iron or graphite steel, The fourth feature is that they are integrated by welding by a centrifugal casting method.

In the roll outer layer material having the first feature, the content of C is 1.5 to 3.0% by weight. C
Combines with Cr, Mo, W, and V to form high hardness carbides (M ₇ C
₃ type, M ₂ C type, M ₆ C type, MC type etc.) to increase the abrasion resistance of the roll. If the content is less than 1.5% by weight, the amount of carbide generated is insufficient, and the wear resistance during hot operation is insufficient. On the other hand, if it exceeds 3.0% by weight, the amount of carbide is too large,
Decreases toughness and heat crack resistance.

[0007] The content of Si is 0.2 to 3.0% by weight. Si
Has the effect of improving the deoxidation of the molten metal and the castability. If it is less than 0.2% by weight, the effect is insufficient, while if it exceeds 3.0% by weight, toughness and mechanical properties are deteriorated.

The content of Mn is 0.2 to 2.0% by weight. Mn
Has an effect of deoxidizing the molten metal. If the content is less than 0.2% by weight, a sufficient effect cannot be obtained, and if it exceeds 2.0% by weight, the toughness of the material decreases, which is not preferable.

The content of Cr is 7.0 to 20.0% by weight. Cr
Combines with C to form a high hardness M ₇ C ₃ type eutectic carbide,
It has the effect of increasing wear resistance and toughness. In addition, a part is dissolved in the base to strengthen the base. On the other hand, in conventional high-speed roll materials, MC type carbides are mainly used, whereas M ₇ C ₃
By mainly using type carbide, it is effective in reducing the coefficient of friction and improving the surface roughness resistance. However, if the Cr content is 7.0
If the amount is less than 20% by weight, these effects are insufficient.
If it exceeds 300, the carbide becomes coarse and the amount thereof becomes excessive, and the toughness and the heat crack resistance deteriorate. When the carbide area ratio in the structure is set to M ₇ C ₃ ≧ (M ₂ C + M ₆ C + MC) × 3, as a roll for hot rolling, the coefficient of friction is low, heat crack resistance, seizure resistance, and It is important in improving skin roughness.

The content of Mo is set to 6.0% by weight or less including zero. Mo dissolves in the base, improves the hardenability,
In addition to improving the high-temperature softening resistance, it has the effect of forming a high-hardness double carbide such as M ₂ C-type carbide and M ₆ C-type carbide by combining with C to improve the wear resistance during hot working. However, if the content exceeds 6.0% by weight, coarse M ₂ C-type carbides increase, leading to a decrease in toughness.

The content of W is set to 6.0% by weight or less including zero. W forms a solid solution in the matrix to increase tempering softening resistance and heat resistance, and combines with C to form a high-hardness double carbide such as M ₂ C type or M ₆ C type, thereby improving wear resistance. Improve. However, when the content exceeds 6.0% by weight, carbides are coarsened and segregation tends to occur during production.

The content of V is set to 6.0% by weight or less including zero. V combines with C to form a hardened MC-type carbide most effective for improving wear resistance. However, if it exceeds 6.0% by weight, the abrasion resistance is improved, but the improvement of the rough surface resistance, which is the object of the present invention, cannot be achieved.

The roll outer layer material having the second characteristic is a material having excellent seizure resistance by crystallizing graphite in the structure, but the content of C is 1.5 to 4.0% by weight. . C binds Cr, Mo, W, is V, the high hardness of the carbide (M ₇ C ₃ type, M ₂ C type, M ₆ C-type, MC type) or alone to form a graphite resistance of the roll Increases abrasion and seizure resistance.
If the content is less than 1.5% by weight, the amount of carbide and graphite formed is insufficient, the wear resistance during hot operation is insufficient, and the seizure resistance is not improved. On the other hand, if it exceeds 4.0% by weight, the amount of carbides increases and the toughness decreases.

The Ni content is 1.5-6.0% by weight. Ni
Is an element necessary for crystallizing graphite in the structure, and has an effect of improving hardenability. Its content
If the content is less than 1.5% by weight, these effects are insufficient, while 6.
If it exceeds 0% by weight, an unstable structure such as the presence of retained austenite is formed.

The components of Si, Mn, Cr, Mo, W, and V are the same as the conditions of the components in the first feature. In the second feature, the carbide area ratio in the structure is M ₇ C ₃ ≧ (M ₂ C + M ₆ C + MC) × 3,
The condition is that spheroidal graphite cast iron is crystallized in the structure. By the spheroidal graphite being appropriately crystallized in the structure,
It becomes a roll outer layer material for rolling with a lower coefficient of friction and excellent seizure resistance.

In the outer layer material according to the second feature,
By adjusting the contents of C, Si, and Ni, graphite is crystallized in the structure. By further adding a spheroidizing element of graphite, the graphite to be crystallized is made into spherical graphite. As the spheroidizing element of graphite to be added, for example, two or one of Ca and Mg is used, and by adding the element to, for example, a molten metal, spheroidal graphite is crystallized in the structure. Although the addition amount of Ca and Mg may be small, an amount suitable for spheroidizing the crystallized graphite and having no other undesired effects is obtained in advance by experiments.

The rolling roll according to the third aspect of the present invention is characterized in that the rolling roll has a first or second roll relative to the steel core material.
The molten outer layer material having the characteristics can be integrated soluble adhesive on the outer periphery of the steel-based core, obtaining a rolling roll.

The rolling roll according to the fourth aspect of the present invention is characterized in that the melt of the outer layer material having the first or second aspect is first subjected to centrifugal casting, and then the inner layer of ductile cast iron or graphite steel having high toughness is formed. The roll of the roll can be obtained by putting the molten metal of the material inside the outer layer material, centrifugally casting and welding and integrating them. Further, the roll material manufactured as described above, quenching for texture and hardness adjustment,
A tempering treatment and an annealing treatment for removing residual stress and stabilizing the structure are performed to obtain a roll for rolling according to required characteristics.
Rolling roll outer layer material and rolling roll of the present invention, in addition to wire rod rolling, finishing work roll for hot rolling,
The present invention can be applied to any roll used in a hot state, such as a roll for strip steel rolling and a roll for steel pipe.

[0019]

Examples Examples of the roll outer layer material according to the first feature of the present invention were produced as No. 1 and No. 2. The chemical composition is shown in Table 1. Although the chemical composition condition according to the first feature is satisfied, the carbide area is M ₇ C ₃ ≧ (M ₂ C + M ₆ C + MC)
Those that were out of the condition of × 3 were melted as Comparative Examples No. 3 to No. 5. The chemical composition is shown in Table 1. Further, conventional high-speed materials were melted as conventional examples No. 6 to No. 9. The chemical composition is shown in Table 1. Similarly, Examples of the roll outer layer material according to the second feature of the present invention were produced as No. 10 and No. 11. Table 2 shows the chemical composition. Although the chemical composition condition according to the second feature is satisfied, the carbide area is
What has become a condition outside of _{M 7 C 3 ≧ (M 2} C + M 6 C + MC) × 3, was melted as Comparative Examples No.12 ~ No.14. Table 2 shows the chemical composition. Further, conventional high-speed materials were melted as No. 15 to No. 17 in the conventional example. Table 2 shows the chemical composition.
Shown in In Tables 1 and 2, the underlined component values and the like indicate that the values are out of the range of the components in the present invention.

[0020]

[Table 1]

[0021]

[Table 2]

Each roll outer layer material is subjected to a heat treatment (1000-1200 ° C.) for structure adjustment, hardness adjustment and residual stress removal.
Quenching and tempering at 500-600 ° C)
Was given.

As an evaluation of each of these outer layer materials, measurement of Shore hardness , measurement of the area ratio of carbide , friction wear test, and seizure test were performed. Table 3 shows the results. In the measurement of the area ratio of the carbide, the area ratio for each carbide form was measured by EPMA surface analysis and image analysis (in the case of graphite crystallization, the area ratio of graphite was also measured). In the friction and wear test, the friction coefficient and the wear loss were measured under the following conditions. In the seizure test, the seizure load and the seizure torque were measured by the following Falex method. [Friction wear test] Test method: Pin-on-disk method Test piece temperature: 300 ° C Load: 5 kg / cm ² Rotational speed: 100 m / min Sliding distance: 20000 m [Seizure test] Test method: Falex method (K- F type seizure test machine) Test piece size: φ10 (φ6.5) × 32L Counterpart material (V block): SUS304 Rotation speed: 284rpm

[0024]

[Table 3]

In Examples No. 1 and No. 2 of the roll outer layer material according to the first feature of the present invention, as is clear from Table 3, Comparative Examples No. 3 to No. compared to example Nanba6～nanba9, although somewhat abrasion loss is large and tends seen with M ₇ C ₃ type carbide is increased, there is the friction coefficient is low tendency and seizure resistance is improved Is obtained. From the results shown in Table 3, Examples No. 1 and No. 2 have the effect of considerably improving the problems of the rough surface resistance and the seizure resistance of the conventional high-speed roll material (conventional examples No. 6 to No. 9). We can expect that there is. An actual roll was manufactured using a material considered to be optimal among the outer roll materials for the rolling rolls of Examples No. 1 and No. 2, and a rolling test was performed using this roll for a wire rod intermediate stand. As a result, we succeeded in obtaining the desired satin-like rolled skin.

In Examples No. 10 and No. 11 of the roll outer layer material according to the second feature of the present invention, as is apparent from Table 3, Comparative Examples No. 12 to No. Example No.15
Compared with No.17, the amount of graphite increased in proportion to the increase in Ni content (although there was a relationship with the Si content), and graphite was spheroidized by the addition of Ca and Mg. . And it became clear that the coefficient of friction tends to decrease and the seizure resistance improves with the crystallization amount. Examples
An actual machine roll was manufactured using the material considered to be optimum from the outer roll materials of the No. 10 and No. 11 rolling rolls, and this was actually used as a vertical roll for H-section steel, and a rolling test was actually performed. As a result, compared to conventional high speed rolls, there is no seizure,
Demonstrated good results.

[0027]

According to the roll outer layer material for hot rolling according to the first aspect, while maintaining good wear resistance and heat crack resistance in hot rolling, very good rough surface resistance is exhibited. It is possible to reduce the coefficient of friction and improve seizure resistance. Therefore, it is possible to improve the quality of the rolled product and realize high productivity of the rolling operation. In addition, according to the roll outer layer material of claim 2, by including Ni, crystallized graphite can be obtained in the structure, and the graphite is spheroidized by the addition of a spheroidizing element. Therefore, it is possible to provide a roll for rolling that has reduced friction coefficient and excellent seizure resistance and heat crack resistance while maintaining good wear resistance in hot rolling. Therefore, it is possible to improve the quality of the rolled product and realize high productivity of the rolling operation. Claim 3
According to the rolling roll described in the above, while maintaining abrasion resistance and heat crack resistance, it is possible to exhibit very good surface roughness resistance, reduce the friction coefficient, and improve seizure resistance. be able to. Therefore, it is also possible to improve the quality of the rolled product and achieve high productivity of the rolling operation. According to the rolling roll of the fourth aspect, while maintaining good wear resistance in hot rolling, the friction coefficient can be reduced, and seizure resistance and heat crack resistance can be improved. . Therefore, it is also possible to improve the quality of the rolled product and achieve high productivity of the rolling operation.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takashi Kobe 403 Yoshimi, Otsu-ku, Himeji-shi, Hyogo Pref.

Claims (4)

[Claims] C: 1.5 to 3.0% by weight Si: 0.2 to 3.0% by weight Mn: 0.2 to 2.0% by weight Cr: 7.0 to 20.0% by weight Mo: 6.0% by weight or less W: 6.0% by weight or less V: 6.0% by weight Contains the following, and the balance is substantially a chemical composition consisting of Fe and non-impurities, and has mainly M ₇ C ₃ type eutectic carbide, and the carbide area in the structure is M ₇ C ₃ ≧
(M ₂ C + M ₆ C + MC) × 3, which is a roll outer layer material for rolling. 2. C: 1.5 to 4.0% by weight Si: 0.2 to 3.0% by weight Mn: 0.2 to 2.0% by weight Cr: 7.0 to 20.0% by weight Ni: 1.5 to 6.0% by weight Mo: 6.0% by weight or less W: 6.0% by weight % V: 6.0% by weight or less, the balance being substantially composed of Fe and non-impurities, and having a chemical composition of adding a spheroidizing element of graphite, and having a carbide area in the structure of M ₇ C _3. ≧
(M ₂ C + M ₆ C + MC) × 3 and a roll outer layer material for rolling, characterized in that spheroidal graphite is crystallized in the structure. 3. A rolling roll obtained by welding and integrating a molten steel of an outer layer material having a chemical composition and a structural structure according to claim 1 or 2 and a steel core material by a continuous casting method. . 4. A fusion of the molten outer layer material having the chemical composition and the structural composition shown in claim 1 and the inner layer material made of ductile cast iron or graphite steel by a centrifugal casting method. Roll for rolling.