JPS6116332B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sleeve for use in H-type steel rolling rolls, particularly sleeve rolls for horizontal stands of universal mills. Today, from the standpoint of productivity and quality assurance, universal mills are commonly used for rolling H-shaped steel, as shown in Figure 1. To explain this simply, a universal mill is equipped with a pair of upper and lower horizontal rolls 1, 1 and a pair of left and right vertical rolls 2, 2, and the rolled material (H-beam steel) 3 is passed between these rolls, It is rolled and formed simultaneously from the width direction and the width direction. Here, for the horizontal rolls 1, 1, a sleeve roll assembled by shrink-fitting a separate sleeve 5 to the roll arbor 4 as shown in the figure may be used, based on the difference in the shape of the rolls and the required properties of the parts. is customary. That is, in this type of roll, when the used layer is damaged or worn out by rolling, only the sleeve 5 is modified or replaced with a new one for reuse. However, when looking at the sleeve 5 used in such sleeve rolls for H-type steel rolling, the part that comes into contact with the rolled material 3, that is, the layer used, is required to have seizure resistance, wear resistance, and crack resistance. On the inner surface side of the sleeve that does not contact the rolled material 3, that is, on the inner layer,
Toughness is required to withstand shrink-fitting stress, load stress during rolling, etc. That is, the sleeve 5 that is assembled by shrink-fitting into the arbor 4 is required to have contradictory properties depending on its inner and outer parts. Therefore, conventionally, in the application of this type of sleeve roll, a composite sleeve has often been used, in which the working layer and the inner layer are formed of different materials and are welded together. However, with the recent high demands for ensuring the quality of rolled materials, it has been recognized that even with the use of the above composite sleeve, there are problems in that the performance and durability of the sleeve roll cannot be maintained and improved sufficiently. This is because, in the case of horizontal rolls for rolling H-shaped steel, the layers used in the sleeve 5 are required to have partially different properties. That is, in the web forming part 6 of the sleeve 5, the heat of the rolled material 3 tends to concentrate, so there is a problem that seizure is likely to occur in the part A in the figure. 20 to 40 from the flange tip because it slides with the material flange tip.
There is a problem of severe wear in the B part in the figure, which reaches the mm position, but on the other hand, when spheroidal graphite cast iron is used as the layer material of the composite sleeve, as in the past, it is difficult to prevent seizure. Although it is effective, it has the disadvantage that the local wear progresses significantly and requires modification at an early stage, and when adamite material is used,
This is because although it is effective in improving wear resistance, it leaves a problem in the above-mentioned seizure prevention, and in the end, it is impossible to achieve the required roll performance in either case. Recently, attention has been paid to the fact that adamite material has good wear resistance for the flange forming part 7, and that by increasing its C content, its seizure resistance is generally improved. There is a tendency to use a so-called high C% adamite material as the layer material. However, this high C%
Even with adamite materials, there is a limit to the increase in C content from the standpoint of ensuring accident resistance.
Therefore, the reality is that the problem of seizure in the web forming portion 6 cannot be completely resolved. In view of the above-mentioned problems of sleeve rolls for rolling H-shaped steel, the present invention satisfies all the properties of seizure resistance, wear resistance, and accident resistance required for the layer used in the composite sleeve used in this type of roll. For this purpose, the present invention provides a layer in contact with the rolled material consisting of a first outer layer made of a material with excellent seizure resistance and a second outer layer made of a material with excellent wear resistance. In a three-layer sleeve, the first outer layer, the second outer layer, and the inner layer are integrally welded, the inner layer not in contact with the rolled material is formed of a material with excellent toughness, and the first outer layer, The second outer layer and the inner layer are each made of a material having specific chemical components as detailed below. That is, the three-layer sleeve according to the present invention is a composite sleeve of this kind, which conventionally consisted of two layers, a used layer and an inner layer, and the used layer is further made into two layers, a first outer layer and a second outer layer, made of different materials. This structure simultaneously satisfies the different properties required for each part of the layer used. Figure 2 shows an example of the structure of such a three-layer sleeve, where a is the first outer layer with excellent seizure resistance, and b is the second outer layer with excellent wear resistance.
The outer layer c indicates an inner layer having excellent toughness, and specific examples of materials forming each layer are listed below. For the purpose of understanding the present invention, it is known that three-layer rolls and sleeves have been manufactured and applied for certain uses. In the case of sleeves and sleeves, the purpose of interposing the intermediate layer is to improve the integrity of the weld between the outer layer and the inner layer, but of course the intermediate layer is not used, and the layers used are two-layer rolls and Like the sleeve, it only has an outer layer. In contrast, the three-layer sleeve according to the present invention
As is clear from the above description, both the first outer layer and the second outer layer are used as layers that are directly subjected to rolling, and their technical purpose is clearly distinguished from the conventional three-layer roll and sleeve described above. It is something. Moreover, based on such essential differences, the two will have structures that are significantly different in terms of the materials forming each layer and the layer thickness. Hereinafter, the materials forming the first outer layer, second outer layer, and inner layer of the three-layer sleeve according to the present invention will be listed, and each layer will be explained in detail. [First outer layer] The outer layer with excellent seizure resistance is made of C2.2-3.0%, Si0.2
~1.5%, Mn0.4~1.5%, P0.1% or less, S0.1% or less, Ni2.5% or less, Cr0.5~4.0%, and ≧1.5Si
%, Mo 0.2 to 2.0% by weight, the balance consisting of Fe and normal impurities, or the above components, if necessary, contain one or more of Ti, Al, and Zr in a total amount of 0.1 weight %. It is formed from a material containing less than %. That is, adamite materials generally have good crack resistance, toughness, and wear resistance, but tend to have poor seizure resistance.
However, the seizure resistance tends to be improved by increasing the amount of eutectic cementite and appropriately adjusting the range of alloy components, especially by decreasing the amount of Ni.
In the present invention, the first outer layer is mainly formed of adamite material with improved seizure resistance. (i) Chemical composition (wt%, balance Fe and normal impurities) C; 2.2-3.0% C determines the amount of eutectic cementite that is effective in improving seizure resistance, but if it is less than 2.2%, the amount of carbide is There is little effect on seizure resistance. On the other hand, if it exceeds 3.0%, the toughness and crack resistance will be significantly reduced. Si: 0.2-1.5% Si has a deoxidizing effect and improves seizure resistance, but
On the other hand, it makes the material brittle. If Si is less than 0.2%, gas defects are likely to occur even during centrifugal casting, and seizure resistance deteriorates. On the other hand, if it exceeds 1.5%, problems will arise in terms of crack resistance. Mn: 0.4-1.5% Mn removes the harmful effects of S and contributes to improving hardness and wear resistance. If it is less than 0.4%, there is no effect;
On the other hand, if it exceeds 1.5%, the material becomes brittle. P: 0.1% or less P increases the fluidity of the molten metal and imparts wear resistance and seizure resistance, but it should be kept to 0.1% or less as it makes the material brittle. S: 0.1% or less S is 0.1% because it makes the material brittle like P.
Keep it below. Ni: 2.5% or less Ni increases base hardness, but reduces the high-temperature stability of the structure, deteriorates roughness resistance, and at the same time also deteriorates seizure resistance. If the Ni content exceeds 2.5%, the above-mentioned drawbacks will become noticeable and the first outer layer will no longer be suitable for the intended purpose, so it must be kept below 2.5%. Cr: 0.5 to 4.0% and ≧1.5Si% Cr is effective in strengthening cementite and improving the wear resistance of the matrix, and less than 0.5% is insufficient. However, if the Cr content is too large, cementite tends to crystallize in a net shape, deteriorating the toughness of the material, so it is set to 4.0% or less. In this case, in order to obtain the desired cementite-only state without crystallizing graphite even with the decrease of Cr, it is necessary to adjust the correlation with the Si content.
It is necessary to satisfy the condition of Cr≧1.5Si%. Mo: 0.2 to 2.0% MO has the effect of increasing base hardness and improving wear resistance, but if it is less than 0.2%, the effect is not sufficient. However, if it exceeds 2.0%, there is no corresponding effect and it is economically disadvantageous. Ti, A, and Zr alone or in combination: total amount 0.1% or less Since this material has a C content in the range of 2.2 to 3.0%, casting cavities are likely to occur, so it is recommended to contain one or more of the above elements. This results in healthier materials. However, since all of the above elements are strong deoxidizing agents, excessive addition causes a state of overoxidation, which inhibits the fluidity of the molten metal. Therefore, their total amount can be suppressed to 0.1% or less. Nb, V: 1.0% or less each One or both of Nb and V may be contained as necessary. In other words, Nb is effective in making the casting structure finer and improving the resistance to scratches.
The effect is noticeable at 1.0% or less. Even if it exceeds 1.0%, there is no corresponding effect. V is also contained for the same purpose as Nb, and its content is still
1.0% or less is necessary and sufficient. (ii) Microscopic structure The microscopic structure of this material consists of two phases: cementite and matrix. From the viewpoint of seizure resistance, it is desirable that the base is mainly pearlite (bainite and martensite should be avoided as much as possible). (iii) Thickness of the first outer layer The web forming part 6 is 10 to 50 mm from the roll surface, while the flange tip is usually about 100 mm from the roll surface, so it is 20 to 80 mm from the outer surface.
mm. In addition, when casting, take into consideration the outer surface machining allowance and the welded part with the second outer layer,
The length shall be 130mm. [Second outer layer] The second outer layer, which has excellent wear resistance, contains C1.8 to 3.0%,
Si0.2~1.5%, Mn0.4~1.5%P0.1% or less, S0.1%
Below, Ni0.5~3.5%, Cr0.5~6.0%, Mo0.5~2.5
% by weight, the balance being Fe and normal impurities or one or more of Ti, Al, and Zr as necessary in addition to the above components, in a total amount of 0.1% by weight or less, and/
Alternatively, it is formed from a so-called high C% adamite material containing one or both of Nb 1.0% or less and V1.0% or less in respective weight percentages. (i) Chemical composition (wt%, remainder Fe and normal impurities) C: 1.8 to 3.0% C is contained in an amount of 1.8% or more for the main purpose of providing wear resistance. If it is less than 1.8%, the amount of cementite is small and wear resistance deteriorates. But 3.0
If it exceeds %, the material becomes brittle and is not suitable for its intended use. Si: 0.2-1.5% In this material, Si is mainly used for deoxidation.
If it is less than 0.2%, the effect will be insufficient, while if it exceeds 1.5%, the material will become brittle. Mn: 0.4-1.5% Mn removes the harmful effects of S and contributes to increasing hardness and wear resistance. If it is less than 0.4%, there is no effect;
On the other hand, if it exceeds 1.5%, the material becomes brittle. P: 0.1% or less P increases the fluidity of the molten metal and imparts wear resistance and seizure resistance, but it should be kept to 0.1% or less as it makes the material brittle. S: 0.1% or less S is 0.1% because it makes the material brittle like P.
Keep it below. Ni: 0.5 to 3.5% Ni is contained in an amount of 0.5% or more to increase base hardness and improve wear resistance. However, if the content is too high, thermally unstable martensite will precipitate, causing rough skin, so the upper limit is kept to 3.5% or less. Cr: 0.5-6.0% Cr not only stabilizes cementite, but is also included in cementite to increase its volume, and also makes cementite hard and strong, contributing to improved wear resistance. However, if it is less than 0.5%, the effect will be small, while if it exceeds 6.0%, it will become brittle. Mo: 0.5 to 2.5% Mo increases the base hardness and is required to be included in the second outer layer material, so Mo is contained in an amount of 0.5% or more. But 2.5
If it exceeds %, there will be no corresponding effect and it will be economically disadvantageous. Ti, Al, Zr alone or in combination: total amount 0.1% or less By containing one or more of these elements, the occurrence of casting cavities in this material can be reliably prevented and a healthier material can be obtained.
At this time, since all of the above elements are strong deoxidizing agents, excessive addition causes a state of overoxidation and inhibits the fluidity of the molten metal. Therefore, their total amount can be suppressed to 0.1% or less. Nb, V: 1.0% or less each One or both of Nb and V may be contained as necessary. That is, Nb is effective in making the casting structure finer, and the inclusion of Nb improves wear resistance. This effect is sufficient with Nb of 1.0% or less. V is also contained for the same purpose as Nb, and its content may be 1.0% or less. If it exceeds 1.0%, V or Nb carbide increases and becomes brittle. (ii) Microscopic structure The microscopic structure of this material consists of two phases: cementite and matrix. The base is usually made of pearlite, and can also contain a portion of bainite or martensite depending on the degree of wear resistance required. (iii) Thickness of the second outer layer The thickness of the layer used in this sleeve roll is usually 100 to 2500 mm, including the flange width, and
Excluding the thickness of the outer layer, the second outer layer has a thickness of 20 to 230 mm. In addition, when casting, it is necessary to take into consideration the inner and outer welded parts and set it to 30 to 240 mm. [Inner layer] When this sleeve is assembled and used as shown in Figure 1, the biggest problem is breakage from the inside.
Therefore, the inner layer needs to be made of a material with excellent toughness. There are two types of materials that are suitable for this purpose: (A) graphite steel and (B) spheroidal graphite cast iron, and in the present invention, these are selectively used depending on the purpose of use. Both materials will be explained in detail below. (A) Graphite steel When using graphite steel, the inner layer should be C1.0~2.0
%, Si0.6~3.0%, Mn0.2~1.0%, P0.1% or less, S0.1% or less, Ni0.1~2.0%, Cr0.1~3.0
%, Mo 0.1 to 1.0% by weight, the balance consisting of Fe and normal impurities, or the above components and one or more of Ti, Al, and Zr as required, in a total amount of 0.1% by weight. It is formed from a material containing the following: (i) Chemical composition (wt%, remainder Fe and normal impurities) C: 1.0 to 2.0% C is dissolved in the matrix and appears as graphite (or a portion becomes eutectic cementite). However, if C is less than 1.0%, it will dissolve,
The casting temperature becomes high, which has the disadvantage of increasing costs. On the other hand, if it exceeds 2.0%, the graphite tends to lose its spherical shape, resulting in a decrease in toughness. Si: 0.6 to 3.0% Si has a close relationship with graphite crystallization, and 0.6
%, it becomes almost difficult to crystallize graphite. However, if it exceeds 3.0%,
Si dissolved in the matrix has a remarkable tendency to deteriorate the toughness of the material. Mn: 0.2-1.0% Mn combines with S and is effective in removing the adverse effects of S. If Mn is less than 0.2%, it has no effect, while if it exceeds 1.0%, the toughness of the material deteriorates. P: 0.1% or less P increases the fluidity of the molten metal, but it makes the material brittle, so it should be kept at 0.1% or less. S: 0.1% or less S is 0.1 because it makes the material brittle like P.
% or less. Ni: 0.1 to 2.0% Ni is effective in delaying material transformation and improving toughness. This effect is small when Ni is less than 0.1%, and there is no need to exceed 2.0% Ni. Cr: 0.1 to 3.0% Cr is effective for toughening and stabilizing cementite, and in order to ensure toughness, 0.1% or more is contained. However, if the Cr content is too high, it will become chilled and brittle, and the inner layer will become brittle.
Since the Cr content increases when mixed with the second outer layer, it is desirable to keep it low. The upper limit for graphite crystallization is set at 3.0% or less. Mo: 0.1 to 1.0% Mo, like Ni, is an important element in ensuring toughness. The effect of Mo content cannot be achieved if it is less than 0.1%. However, if it exceeds 1.0%, it becomes hard and on the contrary becomes brittle. Ti, Al, and Zr alone or in combination: Total amount 0.1% or less By containing one or more of these elements, the occurrence of casting cavities in this material with a low C content of 1.0 to 2.0% is reliably prevented. This results in a healthier material being cast. At this time, since all of the above elements are strong deoxidizing agents, excessive addition causes a state of overoxidation and inhibits the fluidity of the molten metal. Therefore, their total amount can be suppressed to 0.1% or less. (ii) Inoculation In order to promote graphitization, contact is generally known to give good results. For this material as well, applying an inoculation technique and adding an inoculant such as CaSi or FeSi in an amount of 0.1 to 1.0% as Si content immediately before casting will be more effective in improving the toughness. The inoculation amount is as above.
There is no effect at less than 0.1%, and there is no need to exceed 1.0%. This inoculation effect is particularly effective when the Cr content increases. In addition, Si after inoculation
The content is adjusted to stay within the above range of 0.6 to 3.0%. (iii) Microscopic structure The microscopic structure of this material consists of two phases: graphite and matrix, and may contain a small amount of eutectic cementite. The base is mainly made of perlite. This material is a so-called graphite steel material. (B) Spheroidal graphite cast iron When using spheroidal graphite cast iron, the inner layer is
C2.8~3.8%, Si1.5~3.2%, Mn0.3~1.0%,
P0.1% or less, S0.03% or less, Ni2.0% or less,
It is formed of a material containing 3.0% or less of Cr, 0.6% or less of Mo, and 0.02 to 0.1% of Mg, with the balance consisting of Fe and normal impurities. (i) Chemical composition (wt%, remainder Fe and normal impurities) C: 2.8 to 3.8% If C is less than 2.8%, the material will become chilled and the toughness will decrease. On the other hand, if it exceeds 3.8%, graphitization will be excessive and strength will be insufficient. Si: 1.5 to 3.2% Si is contained mainly to control graphitization, but if it is less than 1.5%, graphitization will be insufficient.
If it exceeds 3.2%, graphitization becomes excessive and Si dissolved in the ferrite weakens the material. Mn: 0.3-1.0% Mn usually combines with S and is effective in removing the adverse effects of S, but if it is less than 0.3%, it has no effect, while if it exceeds 1.0%, it makes the material hard and brittle. P: 0.1% or less P increases the fluidity of the molten metal, but it makes the material brittle, so it should be kept at 0.1% or less. S: 0.03% or less S must be kept low in order to make the graphite spheroidal, and should be kept at 0.03% or less. Ni: 2.0% or less Ni acts effectively on graphitization and strengthening the base, but if it exceeds 2.0%, the effect is saturated, so from the economic point of view it should be kept at 2.0% or less. Cr: 3.0% or less Cr has a stabilizing effect on cementite, but if it exceeds 3.0%, the material becomes chilled and becomes brittle. Mo: 0.6% or less Mo has a reinforcing effect on the base, but if it exceeds 0.6%, this effect will be saturated and there will be a noticeable tendency to harden the material, so it should be kept at 0.6% or less. Mg: 0.02-0.1% Mg is added to make graphite spheroidized, but if it is less than 0.02%, it has no effect.
On the other hand, if it is added in an amount exceeding 0.1%, it is not preferable because it tends to cause chilling effect of Mg and casting defects such as dross. (ii) Inoculation In order to promote graphitization and refine the structure, inoculation is generally known to give good results. This material also uses inoculation technology to inject CaSi and
Adding an inoculant such as FeSi with a Si content of 1.0% or less is more effective in improving toughness. This is because even if the inoculation amount exceeds the above 1.0%, no further effect can be obtained. In addition, Si after inoculation
The content is adjusted to stay within the above range of 1.5 to 3.2%. (iii) Microscopic structure The microscopic structure of the inner layer material is a so-called spheroidal graphite cast iron material consisting of three phases: spheroidal graphite, a small amount of eutectic cementite, and matrix. In the three-layer sleeve of the present invention, the first outer layer, the second outer layer, and the inner layer each have the above-mentioned materials,
These three layers of different materials are welded together to form an integrated composite sleeve. In addition, in the case of the three-layer sleeve of the present invention, after casting, for the purpose of ensuring the toughness of the material and improving the adjustment of hardness and wear resistance, it is usually heat treated to raise the temperature to the austonite range, and the accompanying heat treatment. Tempering, isothermal transformation, and heat treatment below the eutectoid transformation temperature for strain relief are performed. Next, a method for manufacturing a three-layer sleeve according to the present invention will be briefly described. This kind of three-layer sleeve is
Easily manufactured by using centrifugal casting methods (horizontal, vertical, and inclined). For example, as shown in FIG. 3, the outer layer a, the second outer layer b, and By sequentially casting the molten metals of the inner layer c at appropriate timings, the desired three-layer sleeve metallurgically bonded together is cast. In addition, when casting the inner layer molten metal, as shown in Fig. 4, the mold in which the outer layer and the second outer layer were cast can be stood upright, and the mold can be cast by static casting (however, in this case,
Later, the core is processed and perforated). In the three-layer sleeve thus cast, the first outer layer, second outer layer, and inner layer are metallurgically welded and integrally bonded to each other. In addition,
A mixed layer is inevitably formed at the boundary between each layer. By the way, even with the three-layer sleeve of the present invention,
In actual manufacturing, problems may occur in welding between layers and in the dissolution of alloy elements into other layers. Therefore, in order to solve these problems and manufacture a sleeve that exhibits better performance, it is also desirable to further interpose an intermediate layer between each layer as necessary. In that case, if an intermediate layer is interposed between each layer, the sleeve roll will have a maximum of five layers, but the presence or absence of the intermediate layer and its position must be comprehensively determined in consideration of various points such as economical efficiency. In the case of this sleeve roll, it is generally effective to provide the intermediate layer between the second outer layer and the inner layer. The three-layer sleeve of the present invention produced as described above is usually shrink-fitted into an arbor and used as a sleeve roll. The conventional material for arbor is
SCM-4, SF-60, cast steel, ductile cast iron, etc. are used, and the diameter is usually 500 to 800 mm.
Furthermore, the shrink-fitting ratio is said to be about 0.8×10 ^-3 , but a lubricant or adhesive may be used during shrink-fitting. The material of the arbor is appropriately selected depending on the design of the rolling stand and rolling conditions (rolling load, motor output, etc.). Furthermore, depending on the material of the arbor, etc., the seizure resistance and abrasion resistance, which are the rolling characteristics of the sleeve roll, are not affected.
In addition, accident resistance (resistance to breakage accidents) is
It is determined by the strength and residual stress of the inner surface of the sleeve in the connecting direction, and is not directly related to the material of the arbor. Incidentally, from past experience, it is known that there is no problem if the tensile strength (tangential direction) of the inner surface of the sleeve is 45 Kg/mm ² or more and the residual tensile stress (tangential direction) is 15 Kg/mm ² or less. . Next, embodiments of the present invention will be described together with conventional examples and reference examples. A composite sleeve was manufactured using the materials listed in Table 1. The outer diameter of the composite sleeve is that of Example 2.
930mm, others 1060mm. In the same table, the outer layer of the conventional example is formed of a high C adamite material. The reference example utilizes the present invention, and improves quality by adding auxiliary elements to the first outer layer, second outer layer, and inner layer according to the present invention. The inner layer of Example 1 and Reference Example 1 is made of graphite steel, and the inner layer of Example 2 and Reference Example 2 is made of spheroidal graphite cast iron.

[Table] Material tests were conducted using the composite sleeves shown in Table 1. (i) Seizure resistance Judging from the measurement results of high temperature friction coefficient,
It has been confirmed that there is good agreement in actual rolling. A test piece with a diameter of 300 mm was taken at a depth of 10 to 30 mm from the outer surface of the sleeve, and the high temperature friction coefficient was measured under the following test conditions. Compatible material: SS50, Compatible material diameter: φ270mm Test width: 20mm, Applied load: 100Kg Water cooling: 1.2/min, Test piece rotation speed: 100rpm (ii) Wear resistance Judging from the test results of the Okoshi type abrasion test, the trend value If judged as , it shows the same tendency as the actual rolling results. A test piece with a thickness of 10 mm, width of 20 mm and length of 50 mm was taken in the axial direction at a depth of 100 mm from the outer surface of the sleeve, and the specific wear amount without lubrication was measured under the following test conditions. Sliding speed: 3.4m/sec, Sliding distance: 200m Final load: 17.6~18.5Kg Rotating wheel: SUJ2 (H _RC 60~63) (iii) Accident resistance (resistance to breakage accidents) Sleeve inner surface (inner layer inner surface) The tensile strength and residual stress in the tangential direction were measured. Results The measurement results of (i) to (iii) are shown in Table 2.

[Table] Regarding the sleeve of Reference Example 1, the residual stress in the connection direction (circumferential direction) of other parts of the inner surface of the inner layer was as follows. Sleeve outer surface...4.8Kg/mm ² (compression) 150mm from sleeve outer surface
………2.9Kg/mm ² (compression) In addition, the hardness distribution of the radial cross section of the reference example was
As shown in the figure. From Table 2, it can be seen that the embodiment of the present invention has a higher seizure resistance on the outer surface of the sleeve than the conventional example.
It can be seen that the wear resistance of the middle part of the sleeve (flange molded part) is extremely excellent.
Furthermore, it can be seen that the accident resistance is also good. As described in detail above, the present invention relates to a sleeve for use in an H-type steel rolling roll, particularly a sleeve roll for a horizontal stand of a universal mill.
The layer in contact with the rolled material and the inner layer, which requires toughness, are made of different materials, and in order to meet the requirements for partially different properties, the layer is made of different materials with even better seizure resistance. It is formed of two layers, the first outer layer made of a material and the second outer layer made of a material with excellent wear resistance, and each layer satisfies the required properties, so the web forming part has excellent seizure resistance. The flange molded part has excellent wear resistance, and the inner layer has toughness. Therefore, if the sleeve roll according to the present invention is used, the trouble of seizure during rolling can be effectively prevented, and at the same time, the problem of local wear can be greatly reduced, and it also has sufficient accident resistance against breakage, etc. Thus, this type of rolling roll is provided that is excellent in all aspects of performance, durability, and safety. In addition, in the present invention, either graphite steel or spheroidal graphite cast iron is used as the inner layer material.
All of these have excellent resistance to cracking.
That is, graphite steel has excellent toughness, with a tensile strength of 60 to 70 Kg/mm ² and an elongation of 1.0 to 4.0%. On the other hand, in the case of spheroidal graphite cast iron, the tensile strength is 50~
60Kg/mm ² , elongation 0.5-2.0%, which makes it slightly inferior in toughness compared to graphite steel, but it has the advantage that residual stress is easily released at low temperatures. The linear tensile residual stress) is approximately 60% of that of graphite steel.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional front view of the main part showing the state of rolling of H-shaped steel by a universal mill. FIG. 2 is a sectional view showing an example of the three-layer sleeve structure of the present invention.
FIG. 3 and FIG. 4 are both sectional views showing the manufacturing process of the three-layer sleeve according to the present invention. FIG. 5 is a diagram showing the measured hardness distribution in the radial cross section of a reference example of the three-layer sleeve of the present invention. DESCRIPTION OF SYMBOLS 1...Horizontal roll, 2...Vertical roll, 3...Rolled material (H-shaped steel), 4...Arbor, 5...Sleeve, 6...Web forming part, 7...Flange forming part, a...th 1 outer layer, b...2nd outer layer, c...inner layer.

Claims (1)

[Scope of Claims] 1. The use layer in contact with the rolled material is formed of two layers: a first outer layer made of a material with excellent seizure resistance and a second outer layer made of a material with excellent wear resistance, while an inner layer not in contact with the rolled material is formed. In a three-layer sleeve made of a material with excellent toughness and in which the first outer layer, second outer layer, and inner layer are welded and integrated, the first outer layer contains C: 2.2 to 3.0%, Ni: 2.5% or less. , Si: 0.2 to 1.5%, Cr: 0.5 to 4.0%, Mn: 0.4 to 1.5%, and 1.5 x Si% or more, P: 0.1% or less, Mo: 0.2 to 2.0%, S: 0.1% or less, each weight% The second outer layer consists of C: 1.8-3.0%, Ni: 0.5-3.5%, Si: 0.2-1.5%, Cr: 0.5-6.0%, Mn: 0.4-1.5. %, Mo: 0.5~2.5%, P: 0.1% or less, S: 0.1% or less, and the balance consists of Fe and normal impurities, while the inner layer is C: 1.0~2.0%, Ni: 0.1~ 2.0%, Si: 0.6 to 3.0%, Cr: 0.1 to 3.0%, Mn: 0.2 to 1.0%, Mo: 0.1 to 1.0%, P: 0.1% or less, S: 0.1% or less, and the balance is Fe and A three-layer sleeve for H-shaped steel rolling rolls, characterized by comprising ordinary impurities. 2 The layer used in contact with the rolled material is formed of two layers: the first outer layer made of a material with excellent seizure resistance and the second outer layer made of a material with excellent wear resistance, while the inner layer not in contact with the rolled material is made of a material with excellent toughness. In the three-layer sleeve formed by welding and integrating the first outer layer, second outer layer, and inner layer, the first outer layer contains: C: 2.2 to 3.0%, Ni: 2.5% or less, and Si: 0.2 to 1.5. %, Cr: 0.5-4.0%, Mn: 0.4-1.5%, and 1.5×Si% or more, P: 0.1% or less, Mo: 0.2-2.0%, S: 0.1% or less, and the balance is Fe and normal. The second outer layer contains impurities of: C: 1.8-3.0%, Ni: 0.5-3.5%, Si: 0.2-1.5%, Cr: 0.5-6.0%, Mn: 0.4-1.5%, Mo: 0.5- 2.5% Contains P: 0.1% or less, S: 0.1% or less, and the balance consists of Fe and normal impurities, while the inner layer contains C: 2.8~3.8%, Ni: 2.0% or less, Si: 1.5~ 3.2%, Cr: 3.0% or less, Mn: 0.3 to 1.0%, Mo: 0.6% or less, P: 0.1% or less, Mg: 0.02 to 0.1%, S: 0.03% or less, each weight% contains, the balance is Fe and A three-layer sleeve for H-shaped steel rolling rolls, characterized by comprising ordinary impurities.