JP3004646B1 - Rolling roll - Google Patents

Abstract

An object of the present invention is to provide a roll having good abrasion resistance and excellent seizure resistance and skin roughness, which can be preferably used for hot rolling. SOLUTION: The material constituting the outer layer portion of the rolling roll is:
By weight percent, C: 2.0-3.8%, Si: 1.
0 to 3.5%, Mn: 0.1 to 2.0%, Ni: 0.5
To 10.0%, Cr: 7.0 to 15.0%, Mo: 6.
0% or less, W: 6.0% or less, V: less than 1.0%, C
o: not more than 10.0% (including 0%)
The balance consists essentially of Fe and C- (0.7V +
0.3Mo + 0.2W) ≧ 1.0 and 2.0 ≦ Ni + Co
<10.0, and crystallized graphite is dispersed in the structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rolling roll.

[0002]

2. Description of the Related Art In a rolling roll for hot rolling, a material constituting an outer layer portion is generally required to have rough surface resistance, wear resistance, accident resistance and the like. Examples of roll materials that can meet such demands to some extent include, for example, JP-A-1-96355 and JP-A-2-88745.
High carbon-based high-speed materials, such as those disclosed in Japanese Unexamined Patent Application Publication Nos. WO 88/07594 and WIPO International Publication WO 91/19824, are known. The high-speed material contains several percent of Cr, Mo, W, V, etc., and is suitable as an outer layer material of a hot rolling roll in that it has good wear resistance at high temperatures.

[0003]

However, the above-mentioned conventional HSS material has a structure mainly composed of a very hard MC type carbide, and the hardness difference between the carbide and the matrix is large. There was a problem that the base was worn preferentially and the carbides protruded to the surface, thereby easily increasing the friction coefficient, deteriorating the seizure resistance, or deteriorating the rough surface resistance due to the shedding of the protruded carbides. Further, as a high-speed material in which graphite is crystallized in the structure in order to improve seizure resistance, JP-A-1-287248, JP-A-7-60
No. 30, JP-A-8-209299, etc. are provided, but none of them have yet sufficiently satisfied abrasion resistance, seizure resistance, skin roughness and the like.

Accordingly, the present invention solves the above-mentioned problems related to the conventional rolling rolls, and has excellent wear resistance and excellent seizure resistance and surface roughness resistance, and can be preferably used for hot rolling. To provide

[0005]

According to the present invention, there is provided a roll according to the present invention, wherein a material constituting an outer layer portion of the roll comprises:
By weight percent, C: 2.0-3.8%, Si: 1.
0 to 3.5%, Mn: 0.1 to 2.0%, Ni: 0.5
To 10.0%, Cr: 7.0 to 15.0%, Mo: 6.
0% or less, W: 6.0% or less, V: less than 1.0%, C
o: not more than 10.0% (including 0%)
The balance consists essentially of Fe and C- (0.7V +
0.3Mo + 0.2W) ≧ 1.0, 2.0 ≦ Ni + Co
The first feature is to satisfy <10.0 and disperse crystallized graphite in the structure. The second feature of the rolling roll of the present invention is that, in addition to the first feature, an outer layer is welded and integrated with the outer periphery of the steel core material.

According to the first aspect of the present invention, by forming the outer layer of the roll with a material having the components and structures defined in the above aspect, the roll has good wear resistance as a roll, It is possible to provide a roll that exhibits excellent seizure resistance and surface roughness resistance to a material to be rolled. In addition, when the material constituting the outer layer portion has the above-described composition, the M ₇ C ₃ type eutectic carbide can be mainly dispersed, and the MC type carbide can be suppressed to a low level. M ₇ C
By mainly using type ₃ carbide, wear resistance and toughness of the material can be increased, and improvement in seizure resistance and improvement in skin roughness due to reduction in friction coefficient are expected. Further, by dispersing the crystallized graphite in the structure as the above-mentioned component constitution, the friction coefficient is reduced by the lubricating action, and the seizure resistance is improved. As described above, it is possible to provide a roll particularly excellent in hot rolling.

According to the second aspect, in addition to the above-mentioned effects of the first aspect, since the inner layer is formed of a steel core material, the outer layer having high wear resistance has sufficient toughness. Rolled rolls are expected to be combined with the inner layer part having a good quality and have sufficiently high accident resistance and toughness.

The reason for limiting the content range of each component element in the outer layer material constituting the outer layer portion of the rolling roll of the present invention will be described below.

[0009] The content of C is not less than 2.0% by weight and not more than 3.8% by weight. C combines with Cr, Mo, W, and V to form carbides of high hardness, such as M ₇ C ₃ , M ₂ C, M ₆ C, and MC, and enhances the wear resistance of the rolling roll. If the content is less than 2.0% by weight, the amount of carbide generated is insufficient, and the wear resistance during hot operation is insufficient. On the other hand, when the content exceeds 3.8% by weight, the amount of carbide increases, and the toughness and the heat crack resistance decrease. Therefore, the upper limit is set to 3.8% by weight. Preferably 2.2-
3.5% by weight. The amount of C is C- (0.7V + 0.3Mo + 0.2W) ≧ to obtain a preferable amount of graphite.
It is necessary to satisfy 1.0% by weight.

[0010] The content of Si is 1.0% by weight or more and 3.5% or more.
% By weight or less. Si is an element necessary for ensuring the fluidity of the molten metal and for crystallizing and precipitating graphite. Content is 1.
If it is less than 0% by weight, the desired effect cannot be obtained. On the other hand, 3.
If the content exceeds 5% by weight, the amount of graphite becomes excessive, and there is a possibility that abrasion starting from graphite may become remarkable.
0 to 3.5% by weight. Preferably, it is set to 1.4 to 3.0% by weight. In order to promote the crystallization of graphite, it is preferable that the amount of Si before casting is set to be smaller than the above component range, inoculation is performed at the time of casting, and the content is adjusted within the above range with the components of the final product.

The content of Mn is 0.1% by weight or more and 2.0% or more.
% By weight or less. Mn has a function of increasing the curing ability. Further, it is an element effective for forming MnS by combining with S and preventing embrittlement due to S. On the other hand, if the content is too large, the toughness is reduced. Preferably, it is 0.4 to 1.2% by weight.

Ni is at least 0.5% by weight and 10.0% by weight
The following is assumed. Ni is added for the purpose of improving the base structure and crystallizing and precipitating graphite. If the content is less than 0.5% by weight, the effect is small. If the content exceeds 10.0% by weight, graphite becomes excessive, and retained austenite increases, resulting in a decrease in wear resistance and accident resistance. Therefore, 0.5 to 1
It is specified as 0.0% by weight. Preferably, it is 1.5 to 6.0% by weight. In order to obtain a stable amount of graphite, Ni
If + Co is less than 2.0% by weight, a predetermined amount of graphite cannot be obtained, and if it exceeds 10.0% by weight, the graphitization accelerating effect is saturated, and the retained austenite increases to reduce wear resistance and accident resistance. 2.0 ≦ Ni + Co <10.
It must satisfy 0% by weight.

The content of Cr is not less than 7.0% by weight and 15.
0% by weight or less. Cr combines with C to form high hardness M ₇
To form a C ₃ -type eutectic carbides, the wear resistance, an effect of increasing the toughness. Some also form a solid solution in the base, strengthening the base. On the other hand, the structure of high-speed steel roll
By mainly using M ₇ C ₃ type carbides instead of being mainly C type carbides, seizure resistance and skin roughness resistance were successfully improved with a reduction in the coefficient of friction. However, if the Cr content is less than 7.0% by weight, these effects are insufficient. On the other hand, if it exceeds 15% by weight, the carbides become coarse and the amount of carbides becomes excessive, and the toughness and the heat crack resistance deteriorate. Therefore, the content of Cr is set to 7.0 to 15.0% by weight.

Mo is to be contained in an amount of 6.0% by weight or less. Mo forms a complex carbide of M ₆ C type and M ₂ C type,
Increases room temperature hardness and high temperature hardness, contributing to improvement of wear resistance. However, if the content is too large, it becomes difficult to obtain a desired amount of graphite. Therefore, the upper limit is set to 6% by weight.
Preferably, it is 2.0 to 4.0% by weight.

It is assumed that W is contained in an amount of 6.0% by weight or less. W also binds to C to form M ₂ C type, M ₆
It forms a C-type composite carbide, increases normal-temperature hardness and high-temperature hardness, and contributes to improvement of wear resistance. However, if the content is too large, it becomes difficult to obtain a desired amount of graphite. Therefore, the upper limit is set to 6% by weight. Preferably 1.0 to 3.0
% By weight.

V is contained in an amount of less than 1.0% by weight. V easily combines with C to mainly form MC-type carbides and contributes to improvement of wear resistance. However, if it is contained too much, carbide segregation occurs, C is consumed for carbide formation, and it greatly inhibits crystallization as graphite. Preferably 0.5
To 0.9% by weight.

It is assumed that Co is contained by 10.0% by weight or less (including 0% by weight). Co forms a solid solution in the matrix, and has an effect of improving the hardness of the matrix and increasing the solid solution amount of carbide forming elements such as Cr and Mo in the matrix at a high temperature. Thereby, a large amount of secondary carbides can be precipitated during tempering, and the wear resistance can be improved. If the content exceeds 10.0% by weight, the effect is saturated. Therefore, the content of Co is set to 0 to 10.0% by weight. Preferably, it is 0 to 7.0% by weight. Further, Co is a graphitization promoting element, and in order to obtain a desired amount of graphite, 2.0 ≦ Ni
It is necessary to satisfy + Co <10.0% by weight.

The material of the present invention having the above-mentioned component composition is subjected to quenching and tempering treatment for adjusting the structure and hardness, and annealing treatment for removing residual stress and stabilizing the structure, thereby adjusting to a preferable structure. For example, after casting once, 95
It is quenched from a temperature of 0 ° C. or more and 1100 ° C. or less, tempered at a temperature of 500 ° C. or more and 600 ° C. or less, and used.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the rolling roll of the present invention will be described below. The test material was cast with the target content shown in FIG. 1 and then quenched from 950 to 1100 ° C. as a heat treatment for adjusting the structure and adjusting the hardness and removing the residual stress.
Tempering was performed at 00 to 600 ° C. No. 1 to No. 5
The following are examples of materials constituting the outer layer of the roll used in the rolling roll of the present invention as examples. As a conventional example, a conventional high-speed material was used. 6-No. It is shown in FIG.

As the evaluation of each of these test materials, Shore hardness, area ratio of crystal precipitate, friction and wear test, and seizure test were performed. FIG. 2 shows the evaluation results. The area ratio of the crystal precipitates was determined by EPMA surface analysis and image analysis to measure the area ratio for each carbide form and the graphite area ratio. The friction and wear test was performed by measuring a friction coefficient and a wear loss under the following conditions. In the baking test, a baking load and a baking torque were measured by the following Falex method. <Friction and wear test> Test method: Pin-on-disk method Test piece temperature: 300 ° C Load: 5 kg / cm ² Rotational speed: 100 m / min Distance: 20000 m <Seizure test> Test method: Falex method (KF type seizure tester) Test piece size: φ10 (φ6.5) × 32L Counterpart material (V block): SUS304 Rotation speed: 284 rpm

FIGS. 1 and 2 show that each material No. 1 to
No. In the case of No. 5, although there is a relationship with Si, it became clear that the amount of graphite increases with the increase of Ni, and the friction coefficient decreases with the amount of crystallization, thereby improving seizure resistance.
The effect of improving the surface roughness resistance and seizure resistance of the conventional high-speed roll material is expected. In the embodiment, the No. 1 to N
o. In comparison with No. 2, 3-No. 5 in the _M 7 _{C 3}
The amount of type carbide and graphite is large, and the shear hardness, friction coefficient,
It can be seen that the values of wear loss, seizure load, and seizure torque are better values.

[0022]

According to the present invention, there is provided a rolling roll according to the first aspect, wherein the outer layer of the roll is constituted by a material having components and structures limited in the above features. In addition, the present invention can provide a roll having excellent abrasion resistance as a roll and exhibiting excellent seizure resistance and rough surface resistance to a material to be rolled. That is, while the material constituting the outer layer portion has the above component composition, the M ₇ C ₃ type eutectic carbide is mainly dispersed,
MC-type carbides can be kept low, whereby the wear resistance and toughness of the structure can be increased, and the seizure resistance and the skin roughness can be improved by reducing the friction coefficient. Further, by dispersing the crystallized graphite in the structure, the friction coefficient can be reduced by the lubricating action, and seizure resistance can be improved. As described above, it is possible to provide a roll particularly excellent in hot rolling. According to the rolling roll of the second aspect, in addition to the effect of the first aspect, the outer layer is welded and integrated with the outer periphery of the steel core, so that the inner layer is formed of the steel core. By being composed,
The outer layer portion having high wear resistance is combined with the inner layer portion having sufficient toughness, so that a roll having sufficiently excellent accident resistance (crack resistance) and toughness can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between each specimen No. of the embodiment of the present invention. 1 to No. 5
And each sample No. of the conventional example. 6-No. 9 is a diagram showing components and their target contents in FIG.

FIG. 2 is a diagram showing evaluation test results.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ryuji Tsuji 403 Yoshimi, Otsu-ku, Himeji-shi, Hyogo Pref. 41072 (JP, A) JP-A-9-41091 (JP, A) JP-A-8-209299 (JP, A) JP-A-5-311334 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 27/00 B22D 19/16 C22C 38/00 302 C22C 38/58 C21D 9/38

Claims (2)

(57) [Claims] The material constituting the outer layer portion of the roll is, as weight percent, C: 2.0 to 3.8% Si: 1.0 to 3.5% Mn: 0.1 to 2.0% Ni : 0.5 to 10.0% Cr: 7.0 to 15.0% Mo: 6.0% or less W: 6.0% or less V: Less than 1.0% Co: 10.0% or less (0% And the balance substantially consists of Fe, and C- (0.7V + 0.3Mo + 0.2W) ≧ 1.0;
A rolling roll characterized by satisfying 2.0 ≦ Ni + Co <10.0 and dispersing crystallized graphite in the structure. 2. The rolling roll according to claim 1, wherein an outer layer portion is welded and integrated with the outer periphery of the steel core material.