WO2000051756A1

WO2000051756A1 - Roll for rolling

Info

Publication number: WO2000051756A1
Application number: PCT/JP2000/001020
Authority: WO
Inventors: Yasuhiro Jinbo
Original assignee: Kanto Special Steel Works, Ltd.
Priority date: 1999-02-26
Filing date: 2000-02-23
Publication date: 2000-09-08
Also published as: DE10084289T1; KR20010103013A; TW446588B; GB2367075A; AU2690000A; BR0008967A; GB0122689D0

Abstract

A roll for rolling which has a base material made from a steel containing 0.60 to 1.1 % of C, 0.15 to 3.0 % of Si, 0.15 to 3.0 % of Mn, 3.0 to 12.0 % of Cr, 0.5 to 5.0 % of Mo and 0.5 to 10 % of Co and, on the surface thereof, a hard coating film formed through a surface modification treatment using the PVD method or the CVD method, wherein carbide grains being dispersed on the surface of the basic material to be treated have a maximum equivalent grain diameter of 20 νm or less. The roll has excellent resistance to wear, seizure and accident, and also is excellent in grindability, and moreover can be manufactured at a low cost, which result in marked improvement in the productivity and the surface quality of steel plates.

Description

Description Rolling roll Technical field

The present invention relates to a roll for rolling. More specifically, the present invention relates to a rolling roll suitable for use in cold rolling of thin steel sheets such as common steel and stainless steel, for example. The purpose is to improve the surface quality of thin steel sheets. Background art

Rolls for cold rolling used as tools in the production of thin steel sheets are, of course, required to have excellent wear resistance. In addition, the rolls for cold rolling are required to have excellent grinding properties capable of imparting a predetermined surface condition and roughness, and are also required to be used when an accident such as sheet breakage occurs during rolling. It is also required that the damage is small, that is, the accident resistance is excellent.

On the other hand, in recent years, with the aim of dramatically improving productivity, operations under severe conditions of high speed and high pressure with increased rolling speed and reduction rate have been increasing. When operating under such severe conditions, the temperature of the interface between the cold-rolling roll and the rolled material increases, and the oil film on this interface breaks and seizure easily occurs. For this reason, it is required that the cold rolling roll itself does not easily cause seizure, that is, the seizure resistance.

Furthermore, in order to produce a rolled material with excellent surface quality, the thickness of the oil film at the interface between the cold rolling roll and the rolled material should be made as small as possible. It is also important to transfer the surface condition of the roll to the rolled material as accurately as possible. <As described above, the roll for cold rolling has excellent wear resistance that can maintain the surface condition and roughness over a long period of time, Excellent seizure resistance that does not cause seizure even when the thickness of the oil film is small is required.

By the way, conventionally, as a roll for cold rolling, a high-Cr steel and a high-speed steel In this specification, it is abbreviated as “high speed steel”. ) -Based forged steel rolls have been widely used. Until now, these forged steel pipes have been improved in wear resistance and accident resistance by gradually increasing the alloy while ensuring sufficient grinding performance.

On the other hand, in order to achieve a drastic improvement in productivity and a remarkable improvement in the surface quality of the steel sheet, a roll with small diameter or short length for cold rolling is required to ensure abrasion resistance and seizure resistance. It has also been proposed to use ceramic rolls or carbide rolls having an integral structure or a composite structure with a steel core material.

However, with the wear resistance and accident resistance of the degree obtained by high Cr and high steel forged steel rolls, it is not possible to achieve a dramatic improvement in productivity and a marked improvement in steel sheet surface quality. .

Ceramic rolls and cemented carbide rolls have the desired abrasion resistance and seizure resistance, but have essentially poor ductility and poor accident resistance. Furthermore, these ceramic rolls and carbide rolls are difficult to grind and are expensive. Therefore, it is actually difficult to use these rolls for cold rolling. Disclosure of the invention

It is an object of the present invention to have excellent wear resistance and seizure resistance, which can dramatically improve productivity and significantly improve the surface quality of steel sheets, and also have excellent accident resistance and grindability. Another object of the present invention is to provide a low-cost rolling roll, particularly a cold rolling roll for thin steel sheets.

In order to solve the above-mentioned problems, the present inventor has paid attention to coating a hard film by performing a surface modification treatment on the surface of a roll made of a steel base material. This surface modification treatment is already widely performed in fields other than rolling rolls, for example, in the fields of various cutting tools and dies. However, even when a hard film is formed on the surface of a rolling roll by surface modification treatment, the hard film formed easily peels off under conditions such as cold rolling where high load and high slip are applied. Resulting in. For this reason, use of a roll that has been subjected to a surface modification treatment as a roll for cold rolling has hardly been performed so far. Only the hard chrome roll is realized as a roll for cold rolling, and its excellent wear resistance can extend the life of the roll. Only However, even with this hard Cr plating roll, the Cr plating film is partially exfoliated during rolling, which is excellent enough to dramatically improve productivity and significantly improve the steel sheet surface quality. Abrasion resistance: seizure resistance cannot be obtained at all.

Therefore, the present inventor originally focused on the PVD method and the CVD method as surface modification methods other than the plating method with insufficient adhesion strength for the reasons described below. Actually, cutting tools, dies, and the like in which a hard coating is coated on a predetermined steel composition base material by these methods have already been put to practical use. However, according to the study of the present inventor, even when a hard film is formed by a surface modification treatment using a PVD method or a CVD method, the hard coating between the matrix and the hard film is formed under severe conditions equivalent to cold rolling. It was found that the adhesion strength was insufficient, and considerable improvement was required for its practical use.

Therefore, the present inventor has conducted intensive studies by returning to the root cause of peeling of the hard coating surface-modified by the PVD method or the CVD method. As a result, the present inventors have obtained the new findings (i) to (V i) listed below and completed the present invention.

(i) The maximum equivalent particle size d of the carbide dispersed on the surface of the base material has a strong influence on this peeling. Here, the maximum equivalent particle diameter d _mai of the carbide means the maximum value of the equivalent particle diameter ^ Sc obtained from the area Sc of the carbide particles. The area of each carbide particle is determined using an image analyzer with the surface of the roll substrate as an inspection surface. The maximum equivalent particle diameter d _ma , of the carbide of the steel composition base material for surface modification by the conventional PVD or CVD method was about 30 to 50 m.

Specifically, if the maximum equivalent particle diameter d _{ra ai} of the carbide is 20 im or less, the adhesion between the base material and the hard coating increases, and the rolling conditions under which high load and high slip act are applied. The hard coating does not peel off. For this reason, for example, in the cold rolling of a thin steel sheet such as ordinary steel or stainless steel, it is possible to dramatically improve productivity and remarkably improve the surface quality of the steel sheet.

(ii) This peeling occurs because the structure of the surface layer of the base material under high load and high slip conditions is altered and becomes brittle.

Therefore, by optimizing the composition of the base material so that the surface layer of the base material is unlikely to be degraded, more specifically, by optimizing the C content, the Si content, and the Ni content. To maintain sufficient and long-term adhesion between the substrate and the hard coating even under severe conditions. Can be. For this reason, for example, in the cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and remarkably improve the steel sheet surface quality.

(iiii) This peeling is caused by the difference in rigidity between the carbide of the base material at the interface between the hard coating and the base material and the matrix (matrix).

Therefore, by optimizing the ratio (Cr / C) between the C content of the base material and the Cr amount that balances it, the carbides are softened, and even in cold rolling under severe conditions, the base material and the hard film are hardened. And sufficient adhesion between them can be secured. For this reason, for example, in cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and remarkably improve the steel sheet surface quality.

(i V) This peeling occurs because the structure of the surface layer of the base material under high load and high slip conditions is altered and becomes brittle.

Therefore, it is necessary to optimize the composition of the base material so that the surface layer of the base material is unlikely to be structurally degraded. Specifically, one or more types selected from the group consisting of Ti, Zr, Nb and Ta By adding an appropriate amount of, it is possible to maintain the adhesion between the substrate and the hard coating sufficiently and for a long period of time even under severe conditions. For this reason, for example, in the cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and remarkably improve the steel sheet surface quality.

(V) This peeling occurs in the case of a relatively small-diameter cold rolling roll having a diameter of 300 mm or less because tensile stress remains on the base material surface before surface modification.

Therefore, by adjusting / improving the chemical composition of the base material, quenching it, and using the stress on the base material surface after tempering as the compressive stress, the adhesion between the base material and the film is strong, and the high load / high load Even under severe conditions, peeling of the hard coating can be prevented. For this reason, for example, in cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to achieve a drastic improvement in productivity and a remarkable improvement in steel sheet surface quality.

(Vi) This peeling occurs due to the difference in rigidity between the carbide of the base material at the interface between the hard film and the base material and the matrix as the base.

Therefore, it is necessary to improve the chemical composition of the base material. Specifically, while using a high-speed material with finely dispersed hard carbide for the base, the group consisting of Ti, Zr, Nb, and Ta By adding one or more of the selected ones in an appropriate amount, the adhesion between the base material and the hard coating can be sufficiently maintained, and the hard coating can be peeled even under high load and high slip rolling conditions. Can be prevented. For this reason, for example, in cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and significantly improve the surface quality of steel sheets.

Here, the gist of the present invention is a rolling roll including a steel base material and a hard film formed on the surface of the base material by a surface modification treatment. a rolling roll to a maximum equivalent diameter d _max of the carbide dispersed in the wood table surface is characterized the this is less than 20 / m.

In the rolling roll according to the present invention, the base material is C: 0.60 to 1.1% (hereinafter, unless otherwise specified, "%" means "% by mass" ), Si: 0.15 to 3.0%, Mn: 0.15 to 3.0%, Cr: 3.0 to 12.0%, Mo: 0.5 to 5.0%, Co: 0.5 to 10% is exemplified. ◊

From another viewpoint, the present invention provides: C: 0.30% to less than 0.60%, Si: 0.15% to less than 0.30%, Mn: 0.15 to 3.0%, Ni : 0.3-3.0%, Cr: 2.0-8.0%, Mo: 0.2-3.0%, and surface modification of the surface of this substrate A roll for cold rolling, comprising: a hard coating formed by a treatment.

From another viewpoint, the present invention provides: C: 0.60 to 3.5%, Si: 0.15 to 3.0%, Mn: 0.15 to 3.0%, Mo: 0.5 to 5.0%, Co: 0.5 to 10%, Cr: C ratio (Cr / C) 1 to 4 containing steel base material and surface modification of the surface of this base material And a hard film formed by the treatment.

Further, from another viewpoint, the present invention provides: C: 0.3 to 1.0%, Si: 0.15 to 3.0%, Mn: 0.15 to 3.0%, Cr: 2 0 to 8.0%, Mo: 0.2 to 3.0%, V: 0.05 to 2.0%, and one or more selected from the group consisting of Ti, Zr, Nb, and Ta A total of two or more types: characterized by comprising a steel base material containing 0.01 to 0.50% and a hard coating formed by surface modification on the surface of this base material. It is a roll for rolling.

Further, from another viewpoint, the present invention provides: C: 0.4 to 1.0%, Si: 0.15 to 1.0%, Mn: 0.15 to 1.0%, Cr: 1 0 to 3.0%, Mo: 0.15 to 3.0%, V: 0.5 to 5.0%, and Co: 0.50 to 10.0%, and the surface Zero or compressed surface A rolling roll comprising a steel substrate to which a stress is applied, and a hard coating formed on the surface of the substrate by a surface modification treatment.

From another viewpoint, C: 0.8 to 1.8%, Si: 0.15 to 3.0%, Mn: 0.15 to 3.0%, Cr: 2.0 to 8.0%, Mo: 2.0 to 10.0%, V: 1.0 to 5.0 %, Co: 10.0% or less, and one or more selected from the group consisting of Ti, Zr, Nb and Ta: Total of steel base containing 1.0% or less, and this base material And a hard coating formed by a surface modification treatment on the surface of the roll.

Further, in the rolling roll according to the present invention, it is exemplified that the surface modification treatment is performed by a PVD method or a CVD method. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph showing the results of the adhesion evaluation test in Example 1; FIG. 2 is a graph showing the results of the adhesion evaluation test in Example 2 FIG. 3 is a graph showing the adhesion in Example 3 FIG. 4 is a graph showing the results of the adhesion evaluation test in Example 4. FIG. 5 is a graph showing the results of the adhesion evaluation test in Example 5. FIG. 6 is a graph showing the results of the adhesion evaluation test in Example 5. It is a graph which shows the result of the adhesion evaluation test in Example 6, Detailed description of the invention

Hereinafter, embodiments of the rolling roll according to the present invention will be described in detail for each invention.

(First Embodiment)

〔Base material〕

First, the rolling roll according to the present invention includes a steel base material. Specifically, the roll for rolling according to the present invention comprises: C: 0.60 to 1.1%, Si: 0.15 to 3.0%, Mn: 0.15 to 3.0%, Cr: 3.0 to 12.0%, Mo: 0.5 to 5.0%, Co: : Contains 0.5 to 10%. Hereinafter, the reasons for limiting the composition of the base material will be described.

C: 0.60 to 1.1%

C has a significant effect on both the base hardness of the base material and the formation of carbides. base Is mainly governed by the amount of dissolved C. If the C content is less than 0.60%, the base hardness becomes insufficient, while if the C content exceeds 1.1%,

Due to the relationship with the content of (mainly Cr), coarse _carbides whose maximum equivalent particle diameter d _max exceeds are crystallized, and the adhesion between the base material and the hard coating formed by the surface modification treatment is Is deteriorated. Therefore, in the present invention, the C content is limited to 0.60% or more and 1.1% or less. From the same viewpoint, the lower limit of the C content is preferably 0.7%, and the upper limit is preferably 1.0%.

Si: 0.15 to 3.0%

Si is contained as a deoxidizing agent. Further, as described later, since the base material in the present invention is generally subjected to a high-temperature tempering treatment at a temperature exceeding 400 ° C. before the surface modification treatment, it is necessary to increase the softening resistance during the high-temperature tempering. Is also contained. From these viewpoints, the present invention contains 0.15% or more of Si. On the other hand, if the Si content exceeds 3.0%, hot workability and toughness decrease. Therefore, in the present invention, the Si content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the lower limit of the Si content is desirably 1.0%.

Mn: 0.15 to 3.0%

Mn is contained in the present invention for the same purpose as Si. For this reason, in the present invention, the Mn content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the lower limit of the Mn content is preferably 0.5%, and the upper limit is preferably 2.0%.

Cr: 3.0-12.0%

Cr is a carbide forming element, and when contained at 3.0% or more, has an effect of precipitating fine carbides during tempering to suppress softening. On the other hand, when the Cr content exceeds 12.0%, coarse carbides having a maximum equivalent particle diameter d _ma , exceeding 20 m are crystallized. Therefore, in the present invention, the Cr content is limited to 3.0% or more and 12.0% or less. From the same viewpoint, the upper limit of the Cr content is desirably 10.0%.

Mo: 0.5 to 5.0%

When the Mo content is 0.5% or more, the tempering softening resistance is improved. However, if the Mo content exceeds 5.0%, the toughness deteriorates. Therefore, in the present invention, the Mo content is limited to 0.5% or more and 5.0% or less. From the same viewpoint, the upper limit of the Mo content is 2.0 % Is desirable.

Co: 0.5 to 10%

If the Co content is 0.5% or more, agglomeration of carbides during high-temperature tempering is delayed, and softening is suppressed. The softening inhibitory effect of 10% is sufficient, and adding more than this will only increase the cost. Therefore, in the present invention, the Co content is limited to 0.5% or more and 10% or less. From the same viewpoint, it is desirable that the upper limit of the Co content be 5%.

The base material according to the present invention may be Ni: 2% or less, W: 2% as an optional additive element for the purpose of improving the quenchability of the base material, suppressing tempering softening, and reducing the size of carbides. Hereinafter, V: less than 0.8% may be contained as necessary.

Other than the above, Fe and inevitable impurities.

As described above, since the base material in the present invention has a steel composition, the base material has excellent grinding properties and low cost.

Further, the substrate in the present invention is subjected to a tempering treatment at a temperature exceeding a treatment temperature of a surface modification treatment described later (for example, a temperature exceeding 400 ° C.). It is desirable that the hardness is not less than a predetermined value from the viewpoint of wear resistance. Here, the predetermined hardness is a hardness that does not cause plastic deformation of the base material itself even under the action of a high load during rolling, or a base that does not cause dents and scratches on the surface-modified roll due to foreign matter that has entered during rolling. It is the hardness of the material, specifically, HS 70.

[Surface modification treatment, hard coating]

The roll for rolling according to the present invention is subjected to a surface modification treatment to form a hard coating on the surface of the substrate.

In the present embodiment, the surface modification treatment is performed by a PVD method (physical vapor deposition method) or a CVD method (chemical vapor deposition method). In general, surface modification methods include PVD and CVD, plating, thermal spraying, and TRD (thermal reaction deposition / diffusion). Of these, the plating method and the thermal spraying method originally have a relatively low adhesion strength between the coating and the base material, and are subjected to high load and high slip such as cold rolling. In this case, the coating formed by the plating method or the thermal spraying method is easily peeled off and cannot be put to practical use. On the other hand, according to the TRD method, the substrate is processed at a high temperature exceeding 800 ° C. Is managed. For this reason, if the surface modification treatment is performed after the base material is finished into a roll, the base material having the steel composition undergoes transformation. Is not suitable.

On the other hand, the processing temperature of both the PVD method and the CVD method is usually 200 to 400 ° C, and it is possible to form a film having sufficient adhesion strength to the substrate having the above composition. It does not peel off even under severe cold rolling conditions.

Here, as the PVD method, a vacuum evaporation method, a sputtering method, and an ion plating method can be used. As the CVD method, a plasma CVD method characterized by processing at a lower temperature and lower pressure (the lower limit is 200 ° C and 1 Torr, respectively) is used as compared with a general-purpose thermal CVD method. Is desirable.

[Maximum equivalent particle size of carbide on substrate surface _dmail ]

As mentioned above, a cutting tool in which a base material made of dies and high-speed steel such as SKD11 and SKH51 of J1S standard tool steel is subjected to surface modification treatment by PVD or plasma CVD. And molds are known so far. However, the carbide present on the surface of a substrate such as a cutting tool or a mold is usually coarse carbide having a maximum equivalent particle size of 30 to 50 m. If this is applied to rolling rolls as it is, under rolling conditions such as cold rolling where high loads and high slips are applied, the film will form due to the difference in rigidity between the coarse carbides and the matrix (matrix). It will peel off. Therefore, in the present invention, in order to ensure sufficient peel resistance of the film, the maximum equivalent particle size ^, of carbide on the surface of the substrate is limited to 20 m or less. From the same viewpoint, it is desirable that the maximum equivalent particle diameter d _{raa of the} carbide is 15 im or less.

By limiting the maximum equivalent particle size d _max of the carbide on the surface of the base material to 20 wm or less, a grinding scratch on the surface of the base material is also prevented. That is, the base material is subjected to a grinding finish or the like before the surface modification treatment to give a predetermined surface state.If the maximum equivalent particle diameter d _max of carbide on the surface of the base material is 20 m or less, the grinding wheel The abrasive grains are prevented from falling off, making it difficult for scratches to occur. Scratch in grinding finish etc. has a depth of about 1 to 5 wm and the film thickness is usually about 3 m, so it remains after the surface modification treatment, and the rolled material or the other roll during rolling use In the contact area with the surface, it becomes a source of stress concentration and causes film peeling, but in the present invention, scratches are generated. Since it is difficult to remove, the peeling of the film is also suppressed from this point.

Thus, according to the present invention, it has excellent wear resistance and seizure resistance, which can dramatically improve productivity and significantly improve the surface quality of steel sheets, as well as accident resistance. Rolling rolls with excellent grinding characteristics and low cost are provided.

(Second embodiment)

〔Base material〕

First, the cold rolling roll according to the present invention includes a steel base material. Specifically, the roll for rolling according to the present invention comprises C 0.30% or more and less than 0.60%, Si: 0.15% or more and less than 0.30%, Mn: 0.15 to 3.0%, Ni: 0.3 to 0.3%. 3.0%, Cr: 2.0-8.0%, Mo: 0.2-3.0%. Hereinafter, the reasons for limiting the composition of the base material will be described.

C: 0.30% or more and less than 0.60%

C is one of the main elements that significantly affect various properties in steel materials, and is also an important element in the present invention. If the C content is less than 0.30%, it becomes impossible to obtain the hardness required for a base material described later. On the other hand, if the C content is 0.60% or more, the structural change and embrittlement of the base material are promoted, and the adhesion between the base material and the hard coating cannot be ensured. Therefore, in the present invention, the C content is limited to 0.30% or more and less than 0.60%. From the same viewpoint, it is preferable that the lower limit of the C content is 0.4%.

Si: 0.15% or more and less than 0.3QQ / _Q

Si is contained in an amount of 0.15% or more as a deoxidizing agent. On the other hand, if the Si content is 0.30% or more, the carbides are eccentrically shaped like chains, which promotes embrittlement. Therefore, in the present invention, the Si content is limited to 0.15% or more and less than 0.30%.

Mn: 0.15-3.0%

Mn acts as a deoxidizer. Further, as described later, since the base material in the present invention is usually subjected to a high-temperature tempering treatment exceeding 400 ° C. before the surface modification treatment, Mn is added to increase the softening resistance during the high-temperature tempering. To be included. From this viewpoint, Mn is contained in an amount of 0.15% or more, but if it is contained more than 3.0%, the base material becomes brittle. Therefore, in the present invention, the Mn content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the upper limit of the Mn content is desirably 2.0% or less.

i: 0.3 to 3.0% Ni is an element effective for improving the toughness of a steel material. In particular, in the present invention, there is an effect of delaying tissue deterioration of the base material, and its role is important. When the Ni content is 0.3% or more, such an effect is exhibited. However, when the Ni content exceeds 3.0%, the toughness is rather deteriorated. Therefore, in the present invention, the Ni content is limited to 0.3% or more and 3.0% or less. From the same viewpoint, the lower limit is preferably 0.5%, and the upper limit is preferably 2.0%, and particularly preferably the upper limit is 1.5%.

Cr: 2.0 to 8.0%

Cr is a carbide-forming element and is the element that is most easily dissolved in a base when heated to a high-temperature austenitic state. If the Cr content is 2.0% or more, quenching at a high temperature of 1000 ° C or more and tempering at a high temperature of over 400 ° C will result in significant secondary hardening, which is necessary as a base material High hardness can be ensured. However, when the Cr content exceeds 8.0%, coarse carbides become remarkable, and the toughness is lowered and the hardness is also lowered. Therefore, in the present invention, the Cr content is limited to 2.0% or more and 8.0% or less. From the same viewpoint, the lower limit is desirably 4.0%, and the upper limit is desirably 6.0%.

Mo: 0.2 to 3.0%

Mo is not only a strong carbide-forming element like Cr, but also an element having a stronger effect on tempering resistance and precipitation hardening than Cr. If the Mo content is less than 0.2%, such effects are small, while if it exceeds 3.0%, the toughness is significantly reduced. Therefore, in the present invention, the Mo content is limited to 0.2% or more and 3.0% or less. From a similar viewpoint, the lower limit is desirably 0.5%, and the upper limit is desirably 2.0%.

The base material in the present invention is, as an optional additive element, W: 2% or less, V: 0.8 for the purpose of improving the quenchability of the base material, suppressing temper softening, and reducing the size of carbides. % May be contained as needed.

Other than the above, Fe and inevitable impurities.

Thus, since the base material in the present invention has a steel composition, it has excellent grinding properties and low cost.

Further, the substrate in the present invention is subjected to a tempering treatment at a temperature exceeding a treatment temperature of a surface modification treatment described later (for example, a temperature exceeding 400 ° C.). It is desirable from the viewpoint of abrasion resistance that the surface of the substrate and its vicinity have a predetermined hardness or more. Here, the predetermined hardness is a hardness that does not cause plastic deformation of the base material itself even under the action of a high load during rolling, or a base that does not cause dents and scratches on the surface-modified roll due to foreign matter that has entered during rolling. The hardness of the material, specifically HS70.

[Surface modification treatment, hard coating]

Since the hard coating in the present invention is formed by the same surface modification treatment as the hard coating in the first embodiment described above, the description is omitted.

In the roll for cold rolling according to the present invention having such a configuration, since the composition of the base material, in particular, the C content, the Si content, and the Ni content are all optimized, the structural deterioration of the base material is reduced. It is unlikely to occur. For this reason, even in severe cold rolling, the adhesion between the base material and the hard coating can be sufficiently maintained for a long time. Thus, for example, in cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and to significantly improve the surface quality of steel sheets.

(Third embodiment)

〔Base material〕

The rolling roll according to the present invention includes a steel base material. Specifically, the roll for rolling according to the present invention comprises: C: 0.60 to 3.5%, Si: 0.15 to 3.0%, Mn: 0.15 to 3.0%, Mo: : 0.5 to 5.0%, Co: 0.5 to 10%, satisfying Cr to C ratio (Cr / C) of 1 to 4. Hereinafter, the reasons for limiting the composition of the base material will be described.

C: 0.60-3.5%

C is an element that is necessary for both carbide formation and matrix hardness. In particular, since the substrate in the present invention is tempered at a high temperature exceeding 400 ° C. as described later, 0.60% or more is contained to secure sufficient hardness in this tempering. On the other hand, if the C content exceeds 3.5%, the toughness is significantly deteriorated. Therefore, in the present invention, the C content is limited to 0.60% or more and 3.5% or less. From the same viewpoint, the upper limit of the C content is preferably 1.0%, and more preferably less than 1.0%. Si: 0.15-3.0%

Si is contained as a deoxidizing agent. Also, Si is contained because it has an effect of increasing softening resistance during high-temperature tempering. From this viewpoint, Si is contained at 0.15% or more, but if the Si content exceeds 3.0%, hot workability and toughness are reduced. Therefore, in the present invention, the Si content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the lower limit of the Si content is desirably 1.0%.

Mn: 0.15 to 3.0%

Mn is contained for the same purpose as Si. Therefore, in the present invention, the Mn content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the lower limit of the Mn content is preferably 0.5%, and the upper limit is preferably 2.0%.

Mo: 0.5 to 5.0%

Mo is contained in an amount of 0.5% or more to improve the tempering softening resistance. However, if the Mo content exceeds 5.0%, the toughness of the substrate deteriorates. Therefore, in the present invention, the Mo content is limited to 0.5% or more and 5.0% or less. From the same viewpoint, the upper limit of the Mo content is desirably 2.0%.

Co: 0.5 to 10%

Co has a function of delaying the agglomeration of carbides during high-temperature tempering and suppressing softening, so that it is contained at least -0.5%. However, this effect saturates at a content of 0%, and adding more than this only increases the cost. Therefore, in the present invention, the Co content is limited to 0.5% or more and 10% or less. From the same viewpoint, the upper limit of the Co content is preferably 5%.

Cr: C ratio (Cr / C) 1 to 4

Cr is a carbide forming element, and in the present invention, the type of carbide to be formed is regulated by limiting the relationship with the above-mentioned C content. If the (Cr / C) ratio is 4 or less, the resulting carbides are mainly M ₃ C carbides with a hardness Hv of about 1000, whereas if the (Cr / C) ratio exceeds 4, the hardness Mainly harder M ₇ C ₃ carbide with Hv of about 1800. Therefore, at the interface between the hard coating and the base material, the base material carbide and matrix (matrix hardness: less than HvlOOO) The difference in rigidity of the hard coating increases, and the adhesion between the hard coating and the substrate deteriorates. On the other hand, if the (Cr / C) ratio is less than 1, the hardenability deteriorates and the base hardness is insufficient. Become. Therefore, in the present invention, the (Cr / C) ratio is limited to 1 or more and 4 or less. From the same viewpoint, it is desirable that the upper limit of the (O / C) ratio is 3.

The base material in the present invention may have V: less than 0.8% as an optional additive element for the purpose of improving the hardenability of the base material, suppressing temper softening, and further reducing the size of carbide. May be contained.

Other than the above, Fe and inevitable impurities.

As described above, since the base material of the present invention has a steel composition, it has excellent grinding properties and low cost.

Further, the base material in the present invention is tempered at a temperature higher than a processing temperature of a surface modification process described later (for example, a temperature higher than 400 ° C.). It is desirable from the viewpoint of abrasion resistance that the hardness be equal to or higher than the hardness. Here, the predetermined hardness is such that the base material itself does not undergo plastic deformation even under the action of a high load during rolling, or dents and scratches occur on the surface-modified roll due to foreign matter that has entered during rolling. There is no substrate hardness, specifically, HS70.

[Surface modification treatment, hard coating]

The roll for cold rolling according to the present invention having such a configuration is characterized in that the composition of the base material, in particular, the ratio (Cr / C) of the C content of the base material and the Cr content that balances it, is optimized. Is softened. For this reason, the difference in rigidity between the carbide of the base material and the matrix (matrix hardness: less than Hvl OOO) at the interface between the hard coating and the base material is suppressed to a small value, and cold rolling under severe conditions is performed. In this case, the adhesion between the substrate and the hard coating can be sufficiently ensured. For this reason, for example, in cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and remarkably improve the steel sheet surface quality.

(Fourth embodiment)

[Base material〕

The roll for cold rolling according to the present invention includes a steel base material. Specifically, Rolls for rolling are as follows: C: 0.3% or more and 1.0%, S i: 0.15% or more and 3.0% or less, Mn: 0.5 to 3.0%, Cr: 2. 0 to 8.0%, Mo: 0.2 to 3.0%, V: 0.05 to 2.0%, one or more selected from the group consisting of Ti, Zr, Nb and Ta : Contains 0.01 to 0.50%. Hereinafter, the reasons for limiting the composition of the base material will be described.

C: 0.3% or more and 1.0% or less

C is one of the main elements that significantly affect various properties in steel materials, and is also an important element in the present invention. If the C content is less than 0.3%, it becomes difficult to obtain the hardness required for the base material described later. On the other hand, if the C content exceeds 1.0%, the structure of the base material is deteriorated and embrittlement is promoted, and it becomes impossible to secure the adhesion between the base material and the hard coating. Therefore, in the present invention, the C content is limited to 0.3% or more and 1.0% or less. From the same point of view, it is desirable that the lower limit of the C content is 0.4% and the upper limit is 0.6%.

S i: 0.15% or more and 3.0% or less

Si is added in an amount of 0.15% or more as a deoxidizing agent and to increase the softening resistance when a high-temperature tempering treatment exceeding 400 ° C is performed before the surface modification treatment. On the other hand, if the Si content exceeds 3.0%, the hot workability and toughness decrease. Therefore, in the present invention, the Si content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the upper limit of the Si content is preferably 2.0%.

Mn: 0.15 to 3.0%

Mn acts as a deoxidizer. Further, as described later, since the base material in the present invention is usually subjected to a high-temperature tempering treatment exceeding 400 ° C before the surface modification treatment, the base material contains Mn in order to increase the softening resistance during the high-temperature tempering. Let it. From this viewpoint, Mn is contained in an amount of 0.15% or more, but if it is contained more than 3.0%, the hot workability is reduced and the base material becomes brittle. Therefore, in the present invention, the Mn content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the upper limit of the Mn content is desirably 2.0%.

Cr: 2.0 to 8.0%

Cr is a carbide-forming element and is the element that is most easily dissolved in a base when heated to a high-temperature austenitic state. If the Cr content is 2.0% or more, quenching from a high temperature of 1000 ° C or more and tempering at a high temperature of more than 400 t will result in remarkable secondary hardening, and the hardness required for the base material Can be secured. However, the Cr content is 8. If it exceeds 0%, coarse carbides become remarkable, and as the toughness decreases, the hardness also decreases. Therefore, in the present invention, the Cr content is limited to 2.0% or more and 8.0% or less. From the same viewpoint, the lower limit is desirably 4.0%, and the upper limit is desirably 6.0%.

Mo: 0.2 to 3.0%

Mo is not only a strong carbide-forming element like Cr but also an element having a stronger effect on tempering resistance and precipitation hardening than Cr. If the Mo content is less than 0.2%, the effect is small. On the other hand, if the Mo content exceeds 3.0%, the decrease in toughness becomes remarkable. Therefore, in the present invention, the Mo content is limited to 0.2% or more and 3.0% or less. From the same viewpoint, the lower limit is desirably 0.5%, and the upper limit is desirably 2.0%.

V: 0.05 to 2.0%

V is a strong carbide-forming element that combines with C to form stable carbides. V is an element that hardly forms a solid solution in the matrix than Cr and Mo and, like Mo, has a strong effect on wear resistance and grindability. Thus, since V is a strong carbide-forming element, the amount of V is greatly restricted by the amount of C. If the V content exceeds 2.0%, the C content in the matrix decreases, and the desired hardness cannot be obtained. On the other hand, if the V content is less than 0.05%, the amount of carbide having excellent wear resistance is reduced, and the effect on the desired properties is significantly reduced. Therefore, in the present invention, the V amount is limited to 0.05% or more and 2.0% or less in consideration of the C amount. From the same viewpoint, the lower limit of the V content is preferably 0.1%, and the upper limit is preferably 1.5%.

One or more selected from the group consisting of Ti, Zr, Nb and Ta: 0.01 to 0.50

%

The affinity between these elements and C and N is very strong, and they are crystallized in the form of granular carbide, nitride or carbonitride. These compounds have an effect of preventing crystal grains from being coarsened during quenching of the base material before the surface modification treatment, so that a base material having a fine crystal grain size can be obtained. With a surface-modified roll using this as a substrate, it is possible to suppress the structural alteration and embrittlement of the surface layer of the substrate during rolling. Further, in a base material containing these compounds, softening due to tempering of the base material can be suppressed, so that sufficiently high hardness can be obtained even in high temperature tempering. However, if added excessively, these compounds will segregate, Causes the deterioration of the mechanical properties and the grindability of the base material. Therefore, in the present invention, one or more selected from the group consisting of Ti, Zr, Nb and Ta is limited to 0.01% or more and 0.50% or less in total. It is desirable that the lower limit of these elements is 0.05% and the upper limit is 0.30%.

The base material in the present invention is Ni: 2.0% or less, W: as an optional additive element for the purpose of improving the quenchability of the base material, suppressing tempering softening, and reducing the size of carbides. 2.0% or less, Co: 5.0% or less may be contained as necessary.

Other than the above, Fe and inevitable impurities.

As described above, since the base material in the present invention has a steel composition, it has excellent grinding properties and low cost.

Further, the base material in the present invention is tempered at a temperature higher than a processing temperature of a surface modification process described later (for example, a temperature higher than 400 ° C.). It is desirable from the viewpoint of abrasion resistance that the hardness be equal to or higher than the hardness. Here, the predetermined hardness is a hardness that does not cause plastic deformation of the base material itself even under the action of a high load during rolling, or a base that does not cause dents and scratches on the surface-modified roll due to foreign matter that has entered during rolling. The hardness of the material, specifically HS70.

[Surface modification treatment, hard coating]

The roll for cold rolling according to the present invention having such a configuration is intended to contain a suitable amount of one or two or more selected from the group consisting of T i. Zr, Nb and Ta. Is unlikely to cause organizational deterioration. For this reason, even in severe cold rolling, the adhesion between the base material and the hard coating can be sufficiently maintained for a long time. For this reason, for example, in the cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and remarkably improve the steel sheet surface quality.

(Fifth embodiment)

〔Base material〕 The roll for cold rolling according to the present invention includes a steel base material. Specifically, the rolls for rolling according to the present invention are: C: 0.4% or more and 1.0% or less, Si: 0.15% or more and 1.0% or less, Mn: 0.15 to 1. 0%, Cr: 1.0 to 3.0%, Mo: 0.15 to 3.0%, V: 0.5 to 5.0%, Co: 0.5 to 10.0% At the same time, zero or compression stress is applied to the surface modified surface. Hereinafter, the reason for limiting the composition of the base material will be described together with the surface stress state.

C: 0.4% or more and 1.0% or less

C is an element that has a significant effect on the hardness of the matrix and carbide formation. The hardness of the matrix is mainly governed by the amount of dissolved C. If the C content is less than 0.4%, the base hardness is insufficient. On the other hand, if the C content exceeds 1.0%, coarse carbides are crystallized, and the toughness is deteriorated. Therefore, in the present invention, the C content is limited to 0.4% or more and 1.0% or less. From the same viewpoint, the lower limit of the C content is desirably 0.6%.

S i: 0.15% or more and 1.0% or less

Si is added in an amount of 0.15% or more as a deoxidizing agent and to increase the softening resistance when a high-temperature tempering treatment exceeding 400 ° C. is performed before the surface modification treatment. On the other hand, if the Si content exceeds 1.0%, hot workability and toughness deteriorate. Therefore, in the present invention, the Si content is limited to 0.15% or more and 1.0% or less. From the same viewpoint, the upper limit of the Si content is desirably 0.5%.

Mn: 0.15 to 0%

Mn acts as a deoxidizer. In addition, as described later, since the substrate in the present invention is usually subjected to a high-temperature tempering treatment exceeding 400 ° C. before the surface modification treatment. In order to increase the softening resistance during the high-temperature tempering, Mn is added. To be included. From this viewpoint, Mn is contained in an amount of 0.15% or more, but if it is contained more than 1.0%, the hot workability is deteriorated and the base material becomes brittle. Therefore, in the present invention, the Mn content is limited to 0.15% or more and 1.0% or less. From the same viewpoint, the upper limit of the Mn content is preferably 0.5%.

Cr: 1.0 to 3.0%

Cr is a carbide-forming element and is the element that is most easily dissolved in a base when heated to a high-temperature austenitic state. If the Cr content is 1.0% or more, the secondary hardening is remarkable when quenching is performed from a high temperature of 1000 ° C or more and tempered at a high temperature exceeding 400 t. The hardness required for the base material can be secured. However, when the Cr content exceeds 3.0%, the hardened layer is deep due to high hardenability, and the residual stress after heat treatment becomes a tensile type, which induces peeling of the hard film. Therefore, in the present invention, the Cr content is limited to 1.0% or more and 3.0% or less.

Mo: 0.15 to 3.0%

Mo is a carbide-forming element as strong as O, and has an effect that is equal to or stronger than Cr on tempering resistance and precipitation hardening. If the Mo content is less than 0.15%, such effects are small, while if it exceeds 3.0%, the toughness is significantly reduced. Therefore, in the present invention, the Mo content is limited to 0.15% or more and 3.0% or less.

V: 0.5 to 5.0%

V is a strong carbide-forming element that combines with C to form stable carbides. V is an element that hardly forms a solid solution in the matrix than O and Mo, and, like Mo, has a strong effect on wear resistance and grindability. Thus, since V is a strong carbide-forming element, the amount of V is greatly restricted by the amount of C. If the V content exceeds 5.0%, the C content in the matrix decreases, and the desired hardness cannot be obtained. On the other hand, when the V content is less than 0.5%, granular hard carbide is insufficient, and the adhesion strength at the interface between the hard coating and the base material is insufficient. Therefore, in the present invention, the amount of V is limited to 0.5% or more and 5.0% or less in consideration of the amount of C. From the same viewpoint, the lower limit of the V content is preferably 1.0%, and the upper limit is preferably 3.0%.

Co: 0.5 to 10.0%

Co is added in an amount of 0.5% or more because it has the effect of delaying the aggregation of carbides during high-temperature tempering and suppressing softening. However, even if Co is added in excess of 10.0%, such an effect is saturated and only the cost is increased. Therefore, in the present invention, the Co content is limited to 0.5% or more and 10.0% or less. From the same viewpoint, the lower limit of the Co content is preferably 3.0 / o, and the upper limit is preferably 5.0%.

Others are Fe and inevitable impurities.

It has been empirically known that when a tensile stress acts on the surface of the substrate, which is the surface-modified surface, the adhesion between the film and the substrate is reduced. Therefore, in the present invention, the surface residual stress after heat treatment of the base material is reduced to zero (the stress No condition) or compressive stress. Even if the surface residual stress is a compressive stress, if the value is too large, the adhesiveness is rather deteriorated. Therefore, it is desirable that the surface residual stress be 50 OMPa or less.

Further, the substrate in the present invention is subjected to a tempering treatment at a temperature exceeding a treatment temperature of a surface modification treatment described later (for example, a temperature exceeding 400). Hardness is desirable from the viewpoint of wear resistance. Here, the predetermined hardness is a hardness that does not cause plastic deformation of the base material itself even under the action of a high load during rolling, or a base that does not cause dents and scratches on the surface-modified roll due to foreign matter that has entered during rolling. The hardness of the material, specifically HS70.

[Surface modification treatment, hard coating]

The roll for cold rolling according to the present invention having such a configuration contains a suitable amount of one or more selected from the group consisting of Ti-Zr, Nb and Ta, and Since zero or compressive stress is applied to the surface-modified surface, it is difficult for the base material to undergo structural deterioration. Therefore, even in cold rolling under severe conditions, the adhesion between the base material and the hard coating can be sufficiently maintained for a long time. For this reason, for example, in the cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and remarkably improve the surface quality of the steel sheet.

(Sixth embodiment) [Base material]

The roll for cold rolling according to the present invention includes a steel base material. Specifically, the rolls for rolling according to the present invention are: C: 0.8 to 1.8%, S 0.15 to 3.0%, Mn: 0.15 to 3.0%, Cr: 2.0 to 8.0%, Mo: 2.0 to 10.0%, V: 1.0 to 5.0%, Co: 10.0% or less, and from Ti, Zr, Nb and Ta One or more selected from the group consisting of Total: Contains 1.0 Q / o or less. Hereinafter, the reasons for limiting the composition of the base material will be described.

C: 0.8% or more and 1.8% or less

C has a significant effect on the hardness and carbide formation of the base. The hardness of the matrix is mainly governed by the amount of dissolved C, and if the C content is less than 0.8%, it becomes impossible to obtain the hardness required for a base material described later. On the other hand, if the C content exceeds 1.8%, the toughness is significantly reduced. Therefore, in the present invention, the C content is limited to 0.8% or more and 1.8% or less. From the same viewpoint, it is preferable that the lower limit of the C content is 1.0% and the upper limit is 1.6%.

S i: 0.1 5% or more and 3.0% or less

Si is added in an amount of 0.15% or more as a deoxidizing agent and to increase softening resistance when a high-temperature tempering treatment exceeding 400 t is performed before the surface modification treatment. On the other hand, if the Si content exceeds 3.0%, the hot workability and toughness decrease. Therefore, in the present invention, the Si content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the upper limit of the Si content is preferably 2.0%.

Mn: 0.15 to 3.0%

Mn acts as a deoxidizer. Further, as described later, since the base material in the present invention is generally subjected to a high-temperature tempering treatment exceeding 400 ° C. before the surface modification treatment, Mn is added in order to increase the softening resistance during the high-temperature tempering. To be included. From this viewpoint, Mn is contained in an amount of 0.15% or more, but if it is contained more than 3.0%, the base material becomes brittle. Therefore, in the present invention, the Mn content is limited to 0.15% or more and 3.0% or less. From the same viewpoint, the upper limit of the Mn content is desirably 2.0%.

Cr: 2.0 to 8.0%

Ο is a carbide-forming element and is the element that is most easily dissolved in the base when heated to a high-temperature austenitic state. If the Cr content is 2.0% or more, quenching from a high temperature of 1000 ° C or more and tempering at a high temperature of more than 400 ° C, secondary hardening appears remarkably and is necessary as a base material. High hardness can be ensured. However, when the Cr content exceeds 8.0%, coarse carbides become remarkable, and as the toughness decreases, the hardness also decreases. Therefore, in the present invention, the Cr content is limited to 2.0% or more and 8.0% or less. From the same viewpoint, the lower limit is desirably 3.0%, and the upper limit is desirably 6.0%. Mo: 2.0 ~ 10.0%

Mo is not only a strong carbide-forming element like Cr, but also an element having a stronger effect on tempering resistance and precipitation hardening than Cr. When the Mo content is less than 2.0%, such an effect is small. On the other hand, when the Mo content exceeds 10.0%, coarse carbides are increased and the toughness is significantly reduced. Therefore, in the present invention, the Mo content is limited to 2.0% or more and 10.0% or less. From the same viewpoint, it is preferable that the lower limit is 3.0% and the upper limit is 6.0%.

V: 1.0 to 5.0%

V is a strong carbide-forming element that combines with C to form stable carbides. V is an element that hardly dissolves in the matrix than Cr and Mo, and has a strong influence on wear resistance and grindability like Mo. Thus, since V is a strong carbide-forming element, the V content is greatly restricted by the C content. If the V content exceeds 5.0%, the C content in the matrix decreases, and the desired hardness cannot be obtained. On the other hand, if the V content is less than 1.0%, the amount of carbides having excellent wear resistance is reduced, and coarse carbides become dominant, and the adhesion strength between the coating and the substrate interface becomes insufficient. Therefore, in the present invention, the V content is limited to 1.0% or more and 5.0% or less in consideration of the C content. From a similar viewpoint, the lower limit of the V content is preferably 3.0%, and the upper limit is preferably 5.0% _c

Co: 10.0% or less

Co is added because it has the effect of delaying the aggregation of carbides during high temperature tempering and suppressing softening. However, even if Co is added in excess of 10.0%, such an effect is saturated and only the cost is increased. Therefore, in the present invention, the Co content is limited to 10.0% or less. From the same viewpoint, it is preferable that the upper limit of the Co content is 5.0% and the lower limit is 3.0%.

One or more selected from the group consisting of Ti, Zr, Nb and Ta: 1.0% or less Affinity between these elements and C and N is very strong, and granular carbide, nitride or carbonitrided Crystallizes in the form of a product. Most of the crystallized substances become nuclei during solidification of the eutectic carbide, and suppress the coarsening of the carbide. However, when added in excessive amounts, these compounds are biased, leading to poor mechanical properties and poor grindability of the substrate. Therefore, in the present invention, one or more selected from the group consisting of Ti, Zr, Nb and Ta is limited to 1.0% or less in total. From a similar point of view, the upper limit of these elements is 0.30% and the lower limit is It is desirable to be 0.05%.

The substrate in the present invention may contain W: 10.0% or less, preferably 6.0% or less, as needed, for the purpose of further suppressing temper softening of the substrate. .

Other than the above, Fe and inevitable impurities.

Further, the substrate in the present invention is subjected to a tempering treatment at a temperature exceeding a treatment temperature of a surface modification treatment described later (for example, a temperature exceeding 400 ° C.). It is desirable that the hardness is not less than a predetermined value from the viewpoint of wear resistance. Here, the predetermined hardness is a hardness that does not cause plastic deformation of the base material itself even under the action of a high load during rolling, or a base that does not cause dents and scratches on the surface-modified roll due to foreign matter that has entered during rolling. The hardness of the material, specifically HS70.

[Surface modification treatment, hard coating]

The roll for cold rolling according to the present invention having such a configuration is intended to contain a suitable amount of one or two or more selected from the group consisting of T i. Zr, Nb and Ta. Is unlikely to cause organizational deterioration. For this reason, even in severe cold rolling, the adhesion between the base material and the hard coating can be sufficiently maintained for a long time. For this reason, for example, in the cold rolling of thin steel sheets such as ordinary steel and stainless steel, it is possible to dramatically improve productivity and to significantly improve the surface quality of steel sheets. BEST MODE FOR CARRYING OUT THE INVENTION

Further, the present invention will be described more specifically with reference to examples.

(Example 1)

After quenching the nine types of base materials No. 1 to No. 9 shown in Table 1, they were tempered at a temperature higher than the PVD processing temperature (400 ° C) and hardened to a hardness of HS70 or higher. After that, the table Finishing was performed on a cylindrical test material (diameter: 30 mm, width: 8 MI) with a uniform surface roughness Ra of 0.1 wm on the cylindrical surface to be surface-modified. Then, a ΤίΝ film having a thickness of 3 μm was formed by the PVD method. Then, an adhesion evaluation test between the film and the substrate was performed.

[table 1 ]

The adhesion evaluation test is a rolling / sliding contact of two cylinders with a test material of the same shape. The test material used was 0.8% C-5% Cr forged steel, which is the standard steel for rolling rolls, and its hardness was set to HS70 by quenching and tempering.

As test conditions, the contact pressure was set to 200 MPa at the maximum contact pressure of Hertz. This value corresponds to the maximum surface pressure in actual cold rolling. In addition, the slip ratio of the two cylinders was set to 5%, and rolling was performed at a rotational speed of 800 rpin in kerosene lubrication with poor lubricity. The presence or absence of peeling of the film was determined by suspending the test after an appropriate number of rollings and observing the surface condition using a CCD scope under magnification.

Figure 1 summarizes the test results. The graph in Fig. 1 shows the relationship between the maximum equivalent particle size d „,, (u) and the number of rollings (number) up to failure.

Base material No.1 of conventional example (SKD 1I), Base material No.2 of conventional example (SKD 51) In each of the base materials of Comparative Example No. 9 and the base material, the maximum equivalent particle size of the carbide exceeded the range of the present invention. The film formed exfoliated up to 4 × 10 ⁵ or less).

On the other hand, in the case of the substrate No. 8 of the present invention in which the maximum equivalent particle size of the carbide was 19 wm, even when the number of rollings exceeded the number of rollings used, the film did not peel off. .

In base materials No. 3 to No. 7 having a maximum equivalent particle size of 15 m or less, the fatigue strength of the base material was the direct cause, and the adhesion strength between the coating and the base material was not sufficient. The peeling of the film did not cause damage.

(Example 2)

After quenching the 12 types of base materials No. 1 to No. 12 shown in Table 2, they were tempered at a temperature higher than the PVD processing temperature (400 ° C) to achieve a hardness of HS70 or higher. After that, finishing was performed on a cylindrical test material (diameter 30 mm, width 8 mm) whose surface roughness Ra of the cylindrical surface to be surface-modified was set to 0.1 m. Then, a 3 m-thick TiN film was formed by the PVD method. Then, a test for evaluating the adhesion between the film and the substrate was performed.

[Table 2]

The adhesion evaluation test was performed in the same manner as in Example 1. Figure 2 summarizes the test results for the number of rollings before failure.

The base material of the conventional example of base material No. 1 (SKD 11), the base material of the conventional example of base material No. 2 (SK D51) and the base material of the comparative example of base material No. 3 10 12 Before the number of rolling times of 2 × 10 ⁵ was reached, the formed film peeled off.

On the other hand, all of the base materials of the present invention examples of base material No. 4 to base material No. 9 have the number of use rolling times of 4 × 10 ⁵ (the normal number of cold rolling rolls). Even if the number of rollings used per operation exceeds the value, it could be used sufficiently for actual cold rolling.

(Example 3)

After quenching the eight types of base materials No. 1 to No. 8 shown in Table 3, they were tempered at a temperature higher than the PVD processing temperature (400 ° C) and hardened to a hardness of HS70 or higher. After that, a cylindrical test material (diameter 30) with a uniform surface roughness Ra of 0.1 m for the cylindrical surface to be surface-modified mm, width 8 mra). Then, a 3 m-thick ΤίΝ film was formed by the PVD method. Then, an adhesion evaluation test between the film and the substrate was performed.

[Table 3]

The adhesion evaluation test was performed in the same manner as in Example 1. The test results about the roll number N ₂ until decapsulation, are summarized in the graph in FIG.

The base material of the conventional example of base material No.1 (SKD 11), the base material of base material No.7 and the base material of base material No.8 all reach 2 X 10 ⁵ rolling operations Before that, the formed film had peeled off.

In contrast, the base materials of the present invention examples of base material No. 2 to base material No. 6 each have a used rolling number of 4 × 10 ⁵ times (normal rolling rolls for cold rolling). Even if the number of rollings used per operation exceeds the value, it could be used sufficiently for actual cold rolling.

(Example 4)

After quenching the 18 types of base materials No. 1 to No. 18 shown in Table 4, they were tempered at a temperature higher than the PVD processing temperature (400 ° C) to achieve a hardness of HS70 or higher. After that, a cylindrical test material (diameter of 30 and width of 8) having a surface roughness Ra of 0.1 μm on the cylindrical surface to be surface-modified was finished. Then, a TiN film having a thickness of 3 / m was formed by the PVD method. Then, an adhesion evaluation test between the film and the substrate was performed. [Table 4] Chemical composition (wt%) '

Π ひ、 Remarks

C Si Mn Ni Cr Mo V W Co Ti Zr Nb Ta Ti + Zr + Nb + Ta

1 1.50 * 0.30 0.50 0.01 12.00 * 1.00 0.35 0.01 0.01 0.00 0.00 0.00 0.00 0.00 Conventional substrate (SKD11)

2 0.85 0.30 0.30 0.01 4.15 5.00 * 1.90 6.10 0.01 0.00 0.00 0.00 0.00 0.00 Conventional substrate (SKH51)

3 0.55 1.70 0.55 0.01 4.00 0.75 1.00 0.50 0.01 0.00 0.00 0.10 0.10 0.20 Base material of the present invention

4 0.52 2.70 0.70 1.00 5.25 2.55 0.45 0.50 0.01 0, 05 0.10 0.00 0.00 0.15 Base material of the present invention

5 0.90 0.85 1.70 0.50 4.85 1.25 0.10 0.01 5.00 0.00 0.00 0.01 0.00 0.01 Base material of the present invention

6 0.45 0.55 0.15 0.01 2.50 1.00 1.70 0.01 0.01 0.10 0.00 0.00 0.00 0.10 Base material of the present invention

7 0.50 0.15 1.25 0.01 5.80 2.00 0.35 1.00 0.01 0.10 0.10 0.20 0.05 0.45 Base material of the present invention

8 0.35 0.45 2.70 1.70 4.25 0.35 0.75 0.50 3.50 0.00 0.05 0.00 0.00 0.05 Base material of the present invention

9 0.48 0.35 0.45 0.01 6.00 1.40 0.05 0.01 0.01 0.00 0.05 0.10 0.05 0.20 Base material of the present invention

10 0.60 0.70 2.20 0.01 7.50 0.50 1.45 0.01 0.01 0.05 0.10 0.05 0.05 0.25 Base material of the present invention

11 0.75 1.25 0.85 0.50 5.10 1.85 1.10 1.70 0.01 0.10 0.00 0.20 0.05 0.35 Base material of the present invention

12 0.40 2.20 0.35 0.50 5.50 1.05 0.50 0.01 4.00 0.00 0.10 0.05 0.00 0.15 Base material of the present invention

13 0.50 0.70 1.60 0.01 4.75 1.10 0.35 1.00 0.01 0.00 0.00 0.00 0.00 0.00 * Substrate outside Ti + Zr + Nb + Ta range

14 0.60 1.60 0.55 0.01 5.85 0.55 0.25 0.01 0.01 0.10 0.25 0.15 0.05 0.55 * Ti + Zr + Nb + Ta Substrate out of range

15 0.55 0.35 0.45 0.50 4.95 1.20 1.10 0.01 4.50 0.20 0.20 0:20 0.05 0.65 * Substrate outside Ti + Zr + Nb + Ta range

16 0.40 0.55 0.70 0.01 5.20 1.75 0.45 0.01 0.01 0.05 0.30 0.15 0.10 0.60 * Ti + Zr + Nb + Ta Substrate out of range

17 0.45 1.20 0.35 0.50 5.45 0.95 1.50 0.50 0.01 0.00 0.15 0.25 0.15 0.55 * Substrate outside Ti + Zr + Nb + Ta range

18 1.05 * 0.45 1.20 0.01 4.20 1.45 0.85 0.01 0.01 0.10 0.00 0.10 0.00 0.20 Base material outside C range

The adhesion evaluation test was performed in the same manner as in Example 1. The test results about the roll number N ₂ until decapsulation, shown summarizes the graph in FIG.

The conventional base material of base material No. 1, the conventional base material of base material No. 2, and the base materials of comparative examples of base materials No. 13 to 18 were all used 2 × 10 ⁵ times Before the number of rollings was reached, the formed film peeled off.

On the other hand, the base materials of the present invention examples of base material No. 3 to base material No. 12 each have a used rolling number of 4 × 10 ⁵ times (normal rolling rolls for cold rolling). Even if the number of rollings used per operation exceeds the value, it could be used sufficiently for actual cold rolling.

(Example 5)

After quenching the 12 types of base materials No. 1 to No. 12 shown in Table 5, they were tempered at a temperature higher than the PVD processing temperature (400 ° C) and hardened to a hardness of HS70 or higher. After that, a cylindrical test material (diameter: 30 mm, width: 8 mm) with a surface roughness Ra of 0.1 m for the cylindrical surface to be surface-modified was finished. Then, a TiN film having a thickness of 3 m was formed by the PVD method. Then, an adhesion evaluation test between the film and the substrate was performed. In the present example, the surface temperature was adjusted by the heating temperature and cooling rate before quenching, and by sub-zero treatment.

[Table 5] Chemical composition (wt%) Surface stress

No. Remarks

C Si Mn Cr Mo V Co (MPa)

1 1.50 * 0.30 0.50 12.00 * 1.00 0.35 0.01 50 Conventional substrate (SKD11)

2 0.75 0.35 0.40 1.50 0.45 1.50 3.50-1 100 Base material of the present invention

3 0.60 0.40 0.65 2.75 0.55 0.55 1.00-1 50 Base material of the present invention

4 0.85 0.85 0.35 2.00 0.40 2.00 4.50 -450 Base material of the present invention

5 0.95 0.30 0.20 1.20 0.20 2.25 3.75 -250 Base material of the present invention

6 0.45 0.65 0.15 2.50 2.50 4.50 2.50-1 50 Base material of the present invention

7 0.80 0.25 0.20 1.80 1.50 3.00 8.00 -100 Base material of the present invention

8 0.65 0.15 0.75 2.25 0.50 0.85 3.35-1 10 Base material of the present invention

9 0.75 0.30 0.40 2.05 2.65 1.05 3.15 20 * Substrate outside surface stress range

10 0.85 0.45 0.40 1.50 0.55 2.30 4.50 One 600 * Base material with large surface stress

11 0.75 0.35 0.35 3.50 * 2.00 1.15 3.35 20 * Cr and substrate outside stress range

18 1.05 * 0.40 0.25 1.80 0.45 2.00 3.85 -150 C The adhesion evaluation test was performed in the same manner as in Example 1. Figure 5 summarizes the test results for the number of rollings N before failure.

The base material of the conventional example of base material No.1, the base material of base material No.9, the base material of comparative example of 1K12, and the base material of comparative example of base material No.10 with extremely large compressive stress were all 4 before reaching the X 10 ⁵ times the number of used rolling, the formed film is peeled off.

On the other hand, all of the base materials of the present invention examples of base materials No. 2 to No. 8 have a use rolling number of 4 × 10 ⁵ times (usually, Even if the number of rollings per operation exceeds the number of rollings per use), it could be used sufficiently for actual cold rolling.

(Example 6)

After hardening the 18 types of base materials No. 1 to No. 18 shown in Table 6, tempering at a temperature higher than the PVD processing temperature (400 ° C) and a hardness of HS70 or higher After that, a cylindrical test material (diameter: 30 mm, width: 8 mm) with a surface roughness Ra of 0.1; Then, a TiN film having a thickness of 3 μm was formed by the PVD method. Then, an adhesion evaluation test between the film and the substrate was performed. In the present example, the surface temperature was adjusted by the heating temperature and cooling rate before quenching, and by sub-zero treatment.

[Table 6]

The conventional base materials of base materials Nos. 1 and 2 and the base materials of comparative examples of base materials Nos. 14 to 18 all had a film formed before the number of rolling times of 2 x 10 ⁵ was reached. Peeled off.

On the other hand, all of the base materials of the present invention examples of base material No. 3 to base material No. 13 have the number of used rolling of 4 × 10 ⁵ times (the normal number of cold rolling rolls). Even if the number of rollings per operation exceeds the number of rollings per time), it could be used sufficiently for actual cold rolling. Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, the adhesiveness of a film | membrane and a base material can be improved by the improvement from a base material side in the roll for rolling which performs a surface modification process to a steel base material. The hard coating can be used stably for a long period of time without peeling even in the rolling operation under severe conditions, and it also has excellent wear resistance, seizure resistance, accident resistance and grindability. Furthermore, a low-cost rolling roll could be provided.

Therefore, by applying the rolling roll according to the present invention to cold rolling of thin steel sheets such as ordinary steel and stainless steel, the productivity is dramatically improved and the quality of the steel sheet surface is remarkably improved. Can be improved.

The significance of the present invention having such an effect is extremely remarkable.

Claims

The scope of the claims

1. A rolling roll comprising a steel base material and a hard coating formed by a surface modification treatment on the surface of the base material, the roll being the largest equivalent of carbide dispersed on the surface of the base material A rolling roll having a particle size of 20 wm or less.

2. The substrate is a mass ^{_{0/0, C: 0.60~ 1.1}} %, Si: 0.15~3.0%, Mn: 0.15~ 3.0%, Cr: 3.0 ~12.0%, Mo: 0.5 ~5.0%, Co: The roll for rolling according to claim 1, containing 0.5 to 10%.

3. By mass%, C: 0.30% or more and less than 0.60%, Si: 0.15% or more and less than 0.30%, Mn: 0.15 to 3.0%, Ni: 0.3 to 3.0%, Cr: 2.0 to 8.0%, Mo A roll for rolling, comprising: a steel base material containing 0.2 to 3.0%; and a hard film formed on the surface of the base material by a surface modification treatment.

4. By mass%, C: 0.60-3.5%, Si: 0.15-3.0%, Mn: 0.15-3.0%, Mo: 0.5-5.0%, Co: 0.5-10%, and Cr: C A roll for rolls, comprising: a steel base material having a ratio (Cr / C) of 1 to 4; and a hard skin formed on the surface of the base material by a surface modification treatment.

5. By mass%, C: 0.3 to 1.0%, Si: 0.15 to 3.0%, Mn: 0.15 to 3.0%, Cr:

2.0 to 8.0%, Mo: 0.2 to 3.0%, V: 0.05 to 2.0%, and the sum of one or more selected from the group consisting of Tu Zr, Nb and Ta: 0.01 to 0.50% A rolling roll, comprising: a steel base material to be contained; and a hard coating formed on the surface of the base material by a surface modification treatment.

6. In mass%, C: 0.4 to 1.0%, Si: 0.15 to 1.0%, Mn: 0.15 to 1.0%, Cr: 1.0 to 3.0%, Mo: 0.15 to 3.0%, V: 0.5 to 5.0%, and Co: 0.50 to 10.0

%, And a steel substrate having a surface modified surface to which zero or compressive stress is applied, and a hard film formed by a surface modification treatment on the surface of the substrate. And a roll for rolling.

7. Mass ^{_{0/0, C: 0.8 ~}} 1 · 8%, Si: 0.15~3.0%, Mn: 0.15~3.0%, Cr: 2.0 ~8.0%, Mo: 2.0 ~10.0%, V: 1.0 ~ 5.0 %, Co: 10.0% or less, and. Total of one or more selected from the group consisting of Ti, Zr, Nb, and Ta: 1.0% A roll for rolling, comprising: a steel base material containing the following; and a hard film formed on a surface of the base material by a surface modification treatment.

8. The rolling roll according to any one of claims 1 to 7, wherein the surface modification treatment is performed by a PVD method or a CVD method.