JP2005028453A - Roll for hot rolling and method for manufacturing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roll for hot rolling which is suitably used for a hot-rolling mill for ferrous materials especially a hot-rolling mill which is subjected to excessive thermal load by action of both large friction and specific pressure because it is excellent in durability. <P>SOLUTION: The cast roll for hot rolling or the forged roll for hot rolling has iron base alloy composition which contains 1.0-2.6% C, ≤ 1.2% Si, ≤ 1.2% Mn, ≤ 3.0% Ni, 1.5-6.0% Cr, 1.5-5.0% Mo and W as (Mo+W), 6.0-12.0% V, ≤ 5.0% Co, at least one kind of ≤ 2.0% Ti or ≤ 2.0% Nb and the balance Fe with inevitable impurities. Furthermore, the cast roll for hot rolling or the forged roll for hot rolling has structure which has an MC type carbide in which the area ratio Sr (%) of the carbide, the equivalent grain size √Sc of which is ≥ 1μm, is ≤ 20% is dispersed so that the average value of its intergranular interval Lc (μm) is ≤ 30 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hot-rolling roll and a method for producing the same, for example, because of its excellent durability, a hot-rolling machine for steel materials, in particular, large friction and surface pressure act together to receive an excessive heat load. The present invention relates to a hot rolling roll, such as a hot rolling casting roll and a hot rolling forging roll, which can be suitably used in a hot rolling mill, and a method for producing the same.

  In the rolling of steel materials in recent years, both improvement in quality of rolled products and improvement in economic efficiency are strongly demanded. Especially in hot strip rolling, durability is increased because the rolling load is increasing and the production cost is greatly reduced by expanding the rolling schedule (rolling amount per unit roll). There is a need for a roll for rolling with even better properties.

  For example, with respect to finish rolling of hot strip, as a roll for rolling that meets such a demand, Patent Document 1 discloses that C: 1.5 to 2.5% (hereinafter, unless otherwise specified, “%” is “ ) And V: rolls for hot rolling made of a high C high V wear-resistant material containing 4.5 to 8.0% are disclosed. With the hot rolling roll made of this high C, high V wear-resistant material, the rolling schedule for hot strip finish rolling has been greatly expanded.

  On the other hand, with regard to rough rolling of hot strips, mainly from the viewpoint of energy saving, reduction of the number of rolling mills, rolling at a high pressure reduction, rolling at low speed and high temperature, and the like are being directed. The appearance of a work roll for hot rolling that can withstand such high heat load rolling and that can greatly expand the rolling schedule is eagerly desired.

  For example, in Patent Document 2, as a work roll of a hot strip rough rolling mill, a core material made of spheroidal graphite cast iron and an outer layer made of high Cr cast steel containing C: 0.9 to 1.2% and Cr: 6 to 15% A high-Cr cast steel roll manufactured by centrifugal casting is disclosed and has been used so far.

In recent years, high C high V rolls by centrifugal casting having an outer layer made of a high C high V wear resistant material have also been applied.
According to Patent Document 3, the present applicant also previously described that the equivalent grain size √Sc when the area of carbide on the roll surface is Sc is 10 μm or more, and that the inter-granular spacing of carbides is 50 μm or less on average. A roll for cold rolling composed of an iron-based alloy having a carbide dispersion characteristic with a maximum particle size of 100 μm was proposed. In this proposal, the carbide can increase resistance to linear scratches caused by free hard particles from the material being rolled into the base structure of the roll surface, and the durability of the roll for cold rolling can be improved.

JP-A-3-219047 Japanese Patent Publication No. 1-1542 Japanese Patent Application No. 2000-91760

  However, when these known work rolls are incorporated into hot strip roughing mills and finish rolling mills to perform high heat load rolling or greatly expand the rolling schedule, it is found that there are problems described below. It was.

  First, the high Cr cast steel rolls have reached their limits in wear resistance and rough skin resistance under the current use conditions in hot strip roughing mills. For this reason, it is virtually impossible to use a high Cr cast steel roll to expand the rolling schedule without relaxing the rolling conditions, and it is difficult to cope with high heat load rolling.

  In addition, according to the high C high V type roll, it is certainly possible to greatly expand the rolling schedule by about 2 to 3 times as high as that of the high Cr cast steel roll in normal heat load rolling. However, it has been found that even with a high-C, high-V roll, if the rolling schedule is further expanded than ever, the wear resistance and the rough skin resistance are insufficient. Especially in high heat load rolling where large friction and surface pressure act, the wear of the base structure increases at an accelerated rate, resulting in insufficient wear resistance or seizure of the rolled material to the roll surface. It turned out that it becomes easy to produce the quality defect of a rolled product.

  In addition, by utilizing the action of carbide in the roll for cold rolling disclosed in Patent Document 3, it can be expected that resistance to linear scratches on the roll for hot rolling is improved. However, even in the hot rolling roll disclosed in Patent Document 3, the surface of the material to be rolled in which the scale is crushed is in metal contact with the roll surface, and high temperature, high surface pressure and high friction are obtained. Under such severe conditions, the material to be rolled and the roll base adhere (micro-seize), and the material to be rolled adheres to the roll surface. For this reason, even if it is based on patent document 3, durability of the roll for hot rolling cannot be improved.

  The present invention has been made in view of the problems of such a conventional technique, and not only is excellent in durability, but also a steel steel hot rolling mill, particularly when large friction and surface pressure act together. An object of the present invention is to provide a hot rolling roll that can be suitably used in a hot rolling mill and a method for manufacturing the same, because no adhesion occurs between the material to be rolled even if it receives an excessive heat load. To do.

  In the present invention, the area ratio Sr (%) of carbide having an equivalent particle size √Sc of 1 μm or more, when Sc is the area of carbide on the surface of the roll layer used in the roll body, is more than 10% and 20% or less. A roll for hot rolling characterized by having a structure in which MC type carbides are dispersed so that the average value of the intergranular spacing Lc (μm) thereof is 30 μm or less.

It is exemplified that the hot rolling roll according to the present invention is manufactured by casting or forging.
These rolls for hot rolling according to the present invention have C: 1.0 to 2.6%, Si: 1.2% or less, Mn: 1.2% or less, Ni: 3.0% or less, Cr: 1.5 to 6.0%, Mo and W are Mo + 0. .5W 1.5 to 5.0%, V: 6.0 to 12.0%, Co: 5.0% or less, Ti: 2.0% or less, or Nb: 2.0% or less, the balance Fe and unavoidable It is exemplified that it has a composition comprising impurities.

From another point of view, the present invention, when producing a roll for hot rolling through casting into a mold and solidification, the cooling rate CR (° C./min) in this solidification indicates that the area of carbide on the roll surface is Sc. In order to satisfy the relationship defined by CR ≧ 5.0 × 10 ³ × Sr ^-1.8 with the area ratio Sr (%) of carbide with an equivalent particle size √Sc of 1 μm or more It is a manufacturing method of the roll for hot rolling characterized by performing.

Further, in the present invention, when forging a forging material to produce a roll for hot rolling, the forging ratio FR in this forging is equivalent particle size √Sc when the area of carbide on the roll surface is Sc. Hot rolling characterized by performing forging so as to satisfy the relationship defined by FR ≧ 2.0 × 10 ⁴ · Sr ^-3.6 with the area ratio Sr (%) of carbides of 1 μm or more It is a manufacturing method of an industrial roll.

  According to the present invention, it is possible to develop a roll material excellent in wear resistance, rough skin resistance, and seizure resistance by controlling the dispersion characteristics of carbides. A roll for hot rolling that can be used in a hot rolling mill that works together with surface pressure and receives an excessive heat load, and can be used for future high heat load rolling, and a method for manufacturing the roll. Can be provided.

Embodiments of a hot rolling roll and a method for producing the same according to the present invention will be described below in detail with reference to the accompanying drawings.
First, basic knowledge items 1 to 3 relating to the hot rolling roll of the present embodiment will be described.

(Basic knowledge 1)
By being subjected to rolling under the severe rolling conditions described above, wear, roughening and seizure in the hot rolling roll are considered to occur by the mechanism described below. In other words, wear and roughening are caused by free hard particles such as fine and hard free scale pieces of the material to be rolled crushed by rolling, which bite into the relatively soft base structure around the carbide on the roll surface in the roll bite. It is generated by generating flaws (micro-abrasion) and proceeds by repetition thereafter. Further, seizure occurs when the surface of the material to be rolled with the scale crushed and the roll surface make metal contact. This metal contact is started from a matrix structure around the carbide that is likely to adhere to the rolled material (micro seizure) because it is relatively close to the chemical composition of the rolled material.

(Basic knowledge 2)
By making the structure having a large amount of coarse carbide with an equivalent particle size √Sc of 1 μm or more when the area of carbide on the roll surface is Sc, against the penetration of free hard particles such as fine free scale pieces into the base structure In addition to functioning as a barrier, it can also function as a barrier that stops seizure growth initiated from the base tissue.

(Basic knowledge 3)
Furthermore, by reducing the intergranular spacing Lc (μm) of this coarse carbide compared to conventional rolls, it is possible to improve wear resistance, rough skin resistance, and seizure resistance. Durability can be improved.

Next, the hot rolling roll according to the present embodiment based on these basic findings 1 to 3 will be described.
First, the roll for hot rolling of this Embodiment is equipped with the rolling use layer which consists of an iron-base alloy which has the novel carbide dispersion characteristic mentioned later.

  In the present embodiment, the following iron-based alloy composition is used as a practically preferable composition. In addition, the composition shown below illustrates the composition of the roll for hot rolling of this Embodiment from a practical viewpoint, Comprising: The roll for hot rolling which concerns on this invention is limited to this composition is not. The main body having the effect of the hot rolling roll of the present invention is not the composition but the dispersed state of MC type carbide in the structure as described in the basic knowledge 2.

C: 1.0% or more and 2.6% or less C is an element effective for both the formation of MC-type carbides and securing the base hardness, and is contained by 1.0% or more. On the other hand, if the C content exceeds 2.6%, coarse eutectic carbides increase, leading to deterioration of mechanical properties, making production difficult, and remarkably degrading heat resistance and crack resistance. Therefore, in this embodiment, the C content is limited to 1.0% or more and 2.6% or less. From the same point of view, the C content is preferably 1.4% or more and 2.6% or less, and more preferably 1.8% or more and 2.6% or less.

Si: 1.2% or less
Si can be incorporated up to 1.2% in the same manner as ordinary steel materials for the purpose of adjusting deoxidation, improving fluidity and improving hardenability. From the same viewpoint, the Si content is desirably 0.5% or less.

Mn: 1.2% or less
Mn is contained up to 1.2% in the same manner as ordinary steel materials for the purpose of adjusting deoxidation, improving fluidity and improving hardenability, as with Si. From the same viewpoint, the Mn content is desirably 0.5% or less.

Ni: 3.0% or less
Ni dissolves in the base and is effective in increasing hardenability and heat resistance. Therefore, Ni is contained in an amount of 3.0% or less. From the same viewpoint, the Ni content is desirably 0.5% or less, and more desirably 0.2% or less.

Cr: 1.5% to 6.0%
Cr is added to increase hardenability and high temperature tempering hardness. If the Cr content is less than 1.5%, such an effect is not observed.On the other hand, if the Cr content exceeds 6.0%, the amount of M ₇ C ₃ type and M ₆ C type coarse eutectic carbides increases, Deteriorates heat resistance and crack resistance. Therefore, in this embodiment, the Cr content is limited to 1.5% or more and 6.0% or less. From the same viewpoint, Cr is desirably 5.2% or less.

Mo + 0.5W: 1.5% to 5.0%
Mo and W are added to increase the hardenability and the high temperature tempering hardness in the same manner as Cr. (Mo + O.5W) value can not be observed such an effect is less than 1.5%, whereas, when the (Mo + O.5W) value exceeds 5.0% M ₇ C ₃ type and M ₆ C-type coarse eutectic carbides The amount of crystallization increases and heat resistance and crack resistance deteriorate. Therefore, in this embodiment, the amount of (Mo + O.5W) is limited to 1.5% to 5.0%. From the same viewpoint, the amount of (Mo + O.5W) is desirably 3.5% or less.

V: 6.0% or more and 12.0% or less V contains 6.0% or more as an element forming MC type carbide. On the other hand, if the V content exceeds 12.0%, V segregation tends to occur in the production of a steel ingot, and it becomes difficult to obtain a homogeneous steel ingot. Therefore, in this embodiment, the V content is limited to 6.0% or more and 12.0% or less. From the same viewpoint, it is preferably 8.0% or more and 12.0% or less.

Co: 5.0% or less
Co is dissolved in the base and effective in increasing hardenability and heat resistance, so 5.0% or less is contained. From the same viewpoint, the Co content is desirably 3.2% or less.

At least one of Ti: 2.0% or less or Nb: 2.0% or less
The affinity between Ti or Nb and C or N is very strong and crystallizes in the form of granular carbide, nitride or carbonitride. Most of the crystallized materials become nuclei during solidification of the eutectic carbide, and have an action of suppressing excessive coarsening of the carbide. Therefore, in this embodiment, at least one of Ti and Nb is added. However, addition of Ti or Nb in excess of 2.0% is not preferable because these compounds segregate and cause deterioration of mechanical properties.

Other than the above are Fe and inevitable impurities.
The roll for hot rolling of the present embodiment having such a composition has a novel carbide dispersion characteristic described below based on the basic findings 1 to 3 described above.

  As described above, in the rolling under severe rolling conditions such as hot strip roughing mill and high heat load rolling in finish rolling mill, free hard such as fine free scale pieces crushed and separated from the surface of the material to be rolled. The particles bite into a relatively soft matrix around the carbide on the roll surface within the roll bite, thereby causing flaws (micro wear), and subsequent repetition causes wear and roughening of the roll for hot rolling. . In addition, the surface of the material to be rolled whose scale has been crushed is in metal contact with the roll surface, and the material to be rolled and the roll base adhere to each other under severe conditions of high temperature, high surface pressure and high friction (micro seizure). The process proceeds to seizure of the material to be rolled onto the roll surface.

  Here, the coarse carbide having an equivalent particle diameter √Sc of 1 μm or more when the area of the carbide on the surface of the rolling roll is Sc is not affected by any progress of these wear, rough skin and seizure. It becomes a barrier that inhibits progression.

  Furthermore, the amount of wear and seizure frequency are reduced by reducing the inter-grain spacing Lc (μm) of MC type carbides with an equivalent grain size √Sc of 1 μm or more from an average value of more than 30 μm to 30 μm or less. Can be significantly reduced. Here, the reason why the MC type carbide is used is that the Vickers hardness is 2100 or more and the wear resistance and the rough skin resistance are excellent.

The roll for hot rolling of this embodiment does not need to specify the manufacturing method, and is generally manufactured by controlling the manufacturing conditions as shown below by casting or forging.
First, when manufactured by casting, the hot rolling roll of the present embodiment is manufactured through casting into a mold and solidification. At this time, the roll production conditions for controlling the inter-granular spacing of the MC type carbide to a predetermined value are the average spacing Lc (μm) between the carbides is the cooling rate CR (° C./mm) during solidification and the carbide area ratio Sr. It is defined as (1) by (%).

Lc = 1.6 × 10 ³・ CR ^-0.47・ Sr ^-0.83・ ・ ・ ・ ・ ・ ・ (1)
The reason why the average interval Lc (μm) is defined by the equation (1) is that the larger the cooling rate, the finer the dendrite structure (solidified structure) and the smaller the dendrite tree. This is probably because carbides crystallize between dendrites, and the interval between carbide grains is determined by the amount of crystallization (the amount of carbides).

For this reason, the manufacturing conditions for controlling the MC type carbide intergranular spacing Lc to 30 μm or less are the parts corresponding to the rolling layer used in the roll body at the completion by setting Lc ≦ 30 in the equation (1). , The cooling rate CR (° C / mm) of the solidification process and the area ratio Sr (%) of carbide with an equivalent particle size of 1 μm or more satisfy CR ≧ 5.0 × 10 ³ · Sr ^-1.8. That's fine.

  Here, in the component system of the present embodiment, the amount of MC type carbide is determined as Sr = 1.4 × (V + 1.06 × Ti + 0.55 × Nb) +2.4 depending on the contents of V, Ti, and Nb. . In the present embodiment, the area ratio Sr is limited to more than 10% in order to ensure the remarkable wear resistance required as a hot rolling roll. However, if the area ratio is increased too much, the surface pressure resistance and the heat damage resistance, which are indispensable as a roll for hot rolling, are lowered. Therefore, the area ratio Sr is limited to 20% or less.

  Next, when manufactured by forging, the roll for hot rolling according to the present embodiment is manufactured by forging a forging material, and a roll for controlling the inter-granular spacing of MC-type carbides to a predetermined value. The production conditions can be expressed as in equation (2) by the average interval Lc (μm) between carbides by the forging ratio FR (cross-sectional area ratio before and after forging) and the carbide area ratio Sr (%) in hot forging.

Lc = 2.8 × 10 ²・ FR ^-0.23・ Sc ^-0.83 ・ ・ ・ ・ ・ ・ (2)
The reason why the average interval Lc (μm) is defined by the equation (2) is considered as follows. Since carbides crystallize between dendritic trees of a dendrite structure (solidified structure), the interval between carbide grains varies depending on the amount of crystallization (the amount of carbide). At least up to a carbide content of about 20%, the larger the carbide content, the smaller the inter-carbide spacing. Furthermore, since the diameter reduction by forging reduces the circumference, the interval between carbide grains is also reduced. The carbide intergranular spacing is the intergranular spacing in the circumferential direction.

For this reason, the manufacturing conditions for controlling the inter-granular spacing Lc of the MC-type carbide to 30 μm or less are the portions corresponding to the roll use layer of the roll body at the time of completion by setting Lc ≦ 30 in the formula (2) The forging ratio FR in forging is between FR and 2.0 × 10 ⁴ between the carbide area ratio Sr (%) having an equivalent particle size √Sc of 1 μm or more when the area of carbide on the roll surface is Sc. ^-Forging should be performed so as to satisfy the relationship defined by Sr- ^3.6 .

  Here, in the component system of the present embodiment, the amount of MC type carbide is determined as Sr = 1.4 × (V + 1.06 × Ti + 0.55 × Nb) +2.4 depending on the contents of V, Ti, and Nb. . In the present embodiment, the area ratio Sr is limited to more than 10% in order to ensure the remarkable wear resistance required as a hot rolling roll. However, if the area ratio is increased too much, the surface pressure resistance and the heat damage resistance, which are indispensable as a roll for hot rolling, are lowered. Therefore, the area ratio Sr is limited to 20% or less.

For the same reason, the lower limit of the forging ratio is preferably 1.2, and more preferably 1.4. On the other hand, the upper limit is preferably 4.0 due to forging restrictions in the actual machine.
With this hot rolling roll of this embodiment, the rolling schedule can be greatly expanded, for example, higher than that of a high C high V roll without relaxing the rolling conditions. It can be increased to about twice that of the system roll. In addition, excellent wear resistance, rough skin resistance and seizure resistance can be exhibited even in severe heat load rolling. For this reason, according to the present embodiment, it is possible to provide a hot rolling roll suitable for use as a work roll of a hot strip rough rolling mill or a finishing rolling mill.

Further, the present invention will be described in detail with reference to examples.
Samples of 10 kinds of chemical composition shown in Table 1 (diameter of 15mm in diameter and 65mm in length) were melted in the center of a heating furnace having a predetermined temperature gradient, then moved at a predetermined speed and solidified from one end. .

  As experimental conditions, the sample was melted at 1550 ° C. and then held at 1450 ° C. for 15 minutes. The moving speed (corresponding to the solidification speed) of sample Nos. 1 to 8 and sample No. 10 was set to 20 mm / min, which is close to the maximum value as the actual roll production conditions, but with the same composition as sample No. 1 The moving speed of a certain sample No. 9 was 5 mm / min. Moreover, Sr (%) of sample No. 1-9 is 20% or less, but Sr (%) of sample No. 10 exceeds 20%.

FIG. 1 is a graph showing the relationship between the cooling rate of each sample and Sr (%). Here, the cooling rate (° C. · min ⁻¹ ) was calculated as the product of the temperature gradient obtained from the measurement result of the furnace temperature and the solidification rate.
After completion of the test, the sample was adjusted so that the carbide could be identified by polishing and corrosion using a cross section perpendicular to the solidification direction as a measurement surface, and then the area ratio of carbide and the average interval between grains were measured by image processing. The above results are summarized in Table 1.

  It can be seen that Samples Nos. 1 to 7 and No. 10 in the examples of the present invention have a cooling rate and a carbide amount satisfying an average interval Lc between carbides of 30 μm or less.

Next, the results of evaluating the durability of the sample of the present invention and the sample of the comparative example will be described.
Of the materials shown in Table 1, four types of the present invention examples (No. 1, 2, 3, 6), comparative example (No. 8), and samples outside the scope of the present invention (No. 9, 10) A cylindrical specimen with a diameter of 90 mm was prepared and brought into rolling contact with a counterpart material of the same shape (backup roll material) at a Hertz contact pressure of 250 kgf / mm ² , and the number of revolutions until the specimen surface peeled was fatigue life As evaluated. The results are summarized in Table 2.

  As shown in Table 2, the four types of the inventive examples showed durability equal to or higher than that of the conventional sample No. 8, whereas Sr of Sample Nos. 9 and 10 has an upper limit. Sample No. 10 that exceeded it had a significant decrease in life.

  In addition, from an ingot with a diameter of 110 mm that was die cast so that the same cooling rate as in Example 1 was obtained so that the carbide spacing of the test material was equivalent to that in Table 1, the Shore hardness was obtained by quenching and tempering. Cylindrical specimens with a diameter of 90 mm adjusted to 80 were prepared and subjected to wear resistance evaluation tests. As test conditions, the wear mass after the contact material (diameter 240mm) was heated to 800 ° C by high frequency induction heating and contacted and rolled 10,000 times with water lubrication with a load of 450kgf, a contact width of 15mm and a slip ratio of 6%. It was measured. The results are shown graphically in FIG.

  As shown in the graph of FIG. 2, it can be seen that the four types of the examples of the present invention in which the carbide interval is 30 μm or less are significantly reduced in wear as compared with the comparative example, and show excellent wear resistance.

  The carbide dispersion characteristics of 12 types of forgings shown in Table 3 were investigated. Here, after melting and adjusting the components in a graphite resistance furnace, the test material was cast to a diameter of 110 mm and a length of 180 mm, heated to 1050 ° C., and hot forged using a 500 kg air hammer.

  Carbide characteristics measurement sample is cut out from the surface of forged steel, the surface side is the measurement surface, and the sample is adjusted so that the carbide can be identified by polishing and corrosion, and then the carbide area ratio and the grain in the circumferential direction of the steel ingot The average interval was measured by image processing.

  The results are summarized in Table 3 and FIG. It can be seen that Samples 1 to 10 of the present invention have forging ratios and carbide amounts that satisfy an average interval Lc between carbides of 30 μm or less.

Next, the results of evaluating the wear resistance of the sample satisfying the scope of the present invention and the sample of the comparative example will be described.
Of the materials shown in Table 3, ingots with a diameter of 220 mm were cast for the four types of the present invention examples (No. 1, 5, 9, 10) and the comparative examples (No. 11, 12), and the diameter was reduced to 110 mm with an air hammer. After hot forging, a cylindrical specimen having a diameter of 90 mm, adjusted to a Shore hardness of 80 by quenching and tempering, was produced. The wear resistance was evaluated by rolling with the mating material (diameter 240mm). As test conditions, the mating material was heated to 800 ° C. by high frequency induction heating, and the wear mass after rolling contact 10,000 times with water lubrication with a load of 450 kgf, a contact width of 15 mm, and a slip rate of 6% was measured.

The results are summarized in FIG. It can be seen that the four types of the present invention examples in which the carbide interval is 30 μm or less are significantly reduced in wear as compared with the comparative examples, and show excellent wear resistance.
In addition, about the sample No. 10 in which the fatigue life (durability) of Example 1 was greatly reduced, it is known that the carbide and the structure are refined by forging to improve the life, so that the durability is improved. Forging was attempted for the purpose. However, cracks occurred during hot forging, and it was found that a material exceeding the upper limit of Sr defined in the present invention is inappropriate in terms of forging processability.

6 is a graph showing a result of a cooling rate in Example 1. 3 is a graph showing test results of Example 1. It is a graph which shows the result of the forge ratio in Example 2. 6 is a graph showing the test results of Example 2.

Claims (6)

  MC type carbide with an area ratio Sr (%) of carbide with an equivalent particle size √Sc of 1 μm or more, when Sc is the area of carbide on the surface of the roll layer used in the roll body, is over 10% and 20% or less. A roll for hot rolling characterized by having a dispersed structure so that the average value of the intergranular spacing Lc (μm) is 30 μm or less.   The hot rolling roll according to claim 1, which is manufactured by casting.   The hot rolling roll according to claim 1 manufactured by forging.   In mass%, C: 1.0-2.6%, Si: 1.2% or less, Mn: 1.2% or less, Ni: 3.0% or less, Cr: 1.5-6.0%, Mo and W are Mo + 0.5W, 1.5-5.0%, V : 6.0 to 12.0%, Co: 5.0% or less, Ti: 2.0% or less, or Nb: 2.0% or less, containing at least one of the remaining Fe and unavoidable impurities. The hot rolling roll according to any one of claims 1 to 3. When producing a roll for hot rolling through casting into a mold and solidification, the cooling rate CR (° C./min) in the solidification is equivalent particle size √Sc when the area of carbide on the roll surface is Sc. Hot solidification characterized in that the solidification is performed so as to satisfy the relationship defined by CR ≧ 5.0 × 10 ³ × Sr ^−1.8 with the area ratio Sr (%) of the carbide that is 1 μm or more. A method for producing rolling rolls. When producing a roll for hot rolling by forging a forging material, the forging ratio FR in the forging is a carbide having an equivalent particle size √Sc of 1 μm or more when the area of the carbide on the roll surface is Sc. The method for producing a hot rolling roll characterized by performing the forging so as to satisfy the relationship defined by FR ≧ 2.0 × 10 ⁴ · Sr ^-3.6 between the area ratio Sr (%) .

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