JPH0379084B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a ring roll for rolling steel wire rods, bars, etc. (Prior art) Rolls for steel rolling, especially rolls for finishing rolling mills, are required to have properties such as wear resistance in the part that comes into contact with the rolled material (layer used). A composite roll is used in which a shaft core made of a material is welded and integrated. The composite roll is mainly integrated into a composite roll at the casting stage using a centrifugal casting method. On the other hand, most wire rod rolling mills these days use cemented carbide sintered ring rolls. For example, block mills use ring rolls made of cemented carbide (mainly made of WC powder and Co) as shown in Figure 7. ing.
Further, the ring roll is mechanically fixed to a shaft and used as an assembly roll. (Problems to be Solved by the Invention) When a carbide ring roll is shaft-fitted and used as an assembly roll, the entire ring is made of carbide, which is not only uneconomical but also requires a complicated assembly structure. In other words, when assembling and fixing a ring roll to a shaft, it is necessary to firmly fix it to the shaft using a fixing ring, spacer ring, etc., and also to alleviate the large difference in thermal expansion coefficient between the steel shaft and the carbide ring material. This is because it is necessary. As a result, such assembled rolls are very costly. Therefore, there is a demand for a composite ring roll in which an expensive material is used for the outer layer used for rolling, and an inexpensive tough material is used for the inner layer. One method for manufacturing such a composite ring roll is centrifugal casting. However, in this case, when the inner layer is cast on the outer layer of high alloy material, the inner surface of the outer layer is melted and the high alloy components are mixed into the inner layer, which deteriorates the toughness of the inner layer and reduces the yield of the high alloy material of the outer layer. There are drawbacks that make it worse. The present invention was made in view of the above-mentioned problems, and its purpose is to have a wear resistance that is slightly inferior to that of a carbide ring roll, but to have both wear resistance and seizure resistance, and to be low-cost. Moreover, it is an object of the present invention to provide a composite ring roll having a strong inner layer in which migration of components from the outer layer to the inner layer is suppressed as much as possible. (Means for solving the problem) The following measures were taken to achieve the above objective.
That is, the outer layer of the composite ring roll is
Cr: 10-25% as main component P: 0.25% or more 1.0
% or less and other specific amounts of C and other appropriate alloying components, and the inner layer thereof was formed of steel, and both were diffusion bonded by hot isostatic pressing. In addition, as another means, the outer layer of the composite ring roll may be made of Cr: 10 to 25% as a main component, P: 0.25% to 1.0%, and a specific amount of C and appropriate alloy components. a first outer layer made of high chromium cast iron, and a second outer layer made of ductile cast iron or adamite material, which is integrally cast on the inner surface of the first outer layer; The inner layer formed of a steel material was diffusion bonded by hot isostatic pressing. (Function) According to the means of the present invention, the outer layer has a Cr content of 10 to 25%.
Since it is made of high chromium cast iron material whose main component is P: 0.25% or more and 1.0% or less and other specific amounts of alloying components, there is a hard phosphorus eutectic called steadite in the structure, and the steel wire rod, It has excellent wear resistance and seizure resistance against rolling of bars, etc.
Furthermore, since the inner layer is made of steel, toughness can be ensured in the inner layer. Furthermore, since the two are diffusion bonded by hot isostatic pressing, migration of Cr from the outer layer to the inner layer can be suppressed as much as possible, and the two can be firmly integrated without deteriorating the toughness of the inner layer. According to another method, the outer layer is divided into a first outer layer and a second outer layer, and the second outer layer is formed of ductile cast iron or adamite material. By directly applying hot isostatic pressure to the material, it is possible to prevent a decrease in bonding strength during diffusion bonding. That is, when bonding with the inner layer, if the second outer layer is not present, the high hardness eutectic chromium carbide of the first outer layer will be destroyed at the bonding interface, resulting in deterioration of the interface properties and a decrease in bonding strength. By providing the second outer layer, such drawbacks can be avoided, and the interface properties of the bonding surface between the second outer layer and the inner layer can be improved, and the bonding strength between the outer layer and the inner layer can be improved. (Example) Next, the composite ring roll of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing the structure of a composite ring roll according to the present invention. Composite ring roll 1 has Cr: 10 to 25 in weight%
%, P: 0.1 to 1.0% (excluding 0.1%) of high chromium cast iron outer layer 2 and inner layer 3 of steel are hot isostatically pressed (hereinafter referred to as HIP).
They are integrated by diffusion bonding. As shown in FIGS. 1 and 2, this composite ring roll 1 is made by processing an outer material ring 2' made of high chromium cast iron material and an inner material ring 3' made of strong steel material into appropriate dimensions. After that, the two are fitted and diffusion bonded using HIP processing, and the resulting composite material is processed into the desired shape. In this case, the outer diameter D ₁ ' of the outer layer material ring 2' is larger than the product outer diameter D ₁ in Fig. 1 by the processing allowance, and the inner diameter D ₂ is the boundary between the outer layer 2 and inner layer 3 of the product. The diameter D is the same as ₂ . On the other hand, the outer diameter of the inner material ring 3' is set to _D2 , and the inner diameter D3 _' is naturally smaller than the product inner diameter _D3 by the machining allowance on the inner surface. Also, the width of the material ring is made larger than the product width to account for the processing allowance. The thus obtained outer layer material ring 2' and inner layer material ring 3' are diffusion bonded by HIP processing. As a result, a composite material is obtained in which the mixing of Cr from the outer layer to the inner layer is suppressed as much as possible, and the two are strongly bonded and integrated. Next, the reasons for limiting the composition of the high chromium cast iron forming the outer layer will be explained. The high chromium cast iron has a weight percentage of Cr: 10 to 25% and P: 0.25 to 1.0%, and is a material with extremely excellent wear resistance and seizure resistance.
It is suitable as a rolling material for steel wire rods, bars, etc. Hereinafter, the unit is weight %. C: 2.0 to 4.0% C is within the range that stabilizes the (Fe-Cr) ₇ C ₃ type carbide, and is determined depending on the desired amount of carbide while maintaining a balance with Cr. If the C content is less than 2.0%, the amount of carbides decreases, resulting in insufficient wear resistance. If C exceeds 4.0%, the amount of carbides is too large;
Causes deterioration of mechanical properties. Si: 0.5 to 1.5% Si is necessary to deoxidize the molten metal in an amount of 0.5% or more, but if it exceeds 1.5%, mechanical properties deteriorate. Mn: 0.5-1.5% Mn is necessary in an amount of 0.5% or more as an auxiliary deoxidizer of Si, and is also useful in preventing the adverse effects of S as MnS, but if it exceeds 1.5%, mechanical properties, especially toughness The deterioration is significant. P: 0.25 to 1.0% P is desirable in terms of toughness of the material, but for the purpose of improving seizability, it is desirable to have less P in the roll material.
Actively added to crystallize phosphorus eutectic (steadite). That is, if it is less than 0.25%, the amount of phosphorus eutectic is insufficient, resulting in insufficient seizure resistance. The effect of improving seizure resistance is seen proportionally up to 1.0%, but
If it exceeds 1.0%, the effect is saturated and the amount of crystallization becomes excessive, making the material brittle. S: 0.1% or less The smaller the amount of S in the roll material, the more desirable it is.
The content was set at 0.1% or less to avoid making the material brittle. Ni: 0.5-2.0% Ni is actively added to adjust hardness in order to improve hardenability.
0.5% or more is necessary. However, if it exceeds 2.0%, thermally unstable retained austenite increases, making it difficult to increase hardness. Cr: 10-25% If Cr is less than 10%, many M ₃ C type carbides will crystallize, resulting in decreased toughness and fine uniformity of carbides, while if it exceeds 25%, M ₂₃ C ₆ type carbides will crystallize. The amount of carbides increases and the toughness deteriorates. Mo: 0.5 to 3.0% Mo increases hardening and tempering resistance, and at the same time enters into the carbide, increasing carbide hardness and increasing temper softening resistance. Mo is effective for increasing hardening and tempering resistance, but if it is less than 0.5%, this effect is weak, and 3.0% The effect will be saturated even if it is added beyond 3.0, considering the cost.
% or less. In addition to the above-mentioned alloy components, the high chromium cast iron according to the present invention is formed of substantially Fe, and in order to improve the properties of high chromium cast iron,
One or two of Nb and V can be contained in a total amount of 1.0% or less. Nb is effective in refining the casting structure, and precipitation hardening is promoted by the addition of Nb, but the effect is saturated if it is added in excess of 1.0%, so it should be kept at 1.0% or less in consideration of cost. . V is also added for the same purpose as Nb, but if it exceeds 1.0%, VC carbides increase and Cr carbides decrease, resulting in a decrease in toughness. For this reason, it should be kept at 1.0% or less. The steel material used for the inner layer can be appropriately selected from materials that generally have excellent toughness, such as mechanical structural carbon steel and structural alloy steel. In particular, the use of low carbon, low alloy steel consisting of a ferrite base is suitable for HIP treatment and for quenching the composite material. That is,
The material made of such a ferrite base has a small coefficient of thermal expansion, so the thermal contraction after HIP treatment is small.
Cracking and peeling are less likely to occur on the diffusion bonded surface. In addition, composite materials are subjected to quenching and tempering heat treatment to make the outer layer superior in wear resistance, but if the ferrite base low carbon low alloy steel material is used for the inner layer,
Even if the entire composite material is quenched, the quenching effect does not reach the inner layer, and no deterioration in toughness occurs. If the inner layer has a hardening effect, it is undesirable because breakage tends to occur when the ring roll is fitted into an assembled roll.
It is also possible to subject only the outer layer of the composite material to the quenching heat treatment, but this is more complicated and less productive than treating the entire composite material. Next, a composite ring roll according to another invention will be described with reference to FIG. 3. A composite ring roll 11 according to another invention is the composite ring roll 1 shown in FIG.
different from. That is, the first outer layer 12a, which corresponds to the layer used for rolling, is made of high chromium cast iron, which is the same material as the outer layer 2 according to the first invention and has extremely excellent wear resistance and seizure resistance. Second outer layer 1 made of ductile cast iron or adamite material on the inner surface
2b are integrally cast to obtain a multi-layered outer layer 12, to which an inner layer 3 made of steel is diffusion bonded by HIP processing. According to such means, the first outer layer 12a and the second outer layer 12b can be easily welded and integrated by ordinary centrifugal force casting, and the interface of the joint surface between the second outer layer 12b and the inner layer 3 can be formed by HIP processing. The properties are extremely good and the strength of the boundary is improved. In other words, in order to ensure wear resistance, the first outer layer
A relatively large eutectic carbide crystallizes out, and this eutectic carbide is extremely hard, and its toughness is inferior to that of the base portion even at high temperatures. For this reason, when directly bonding the first outer layer and the inner layer by HIP processing, it is difficult to apply pressure without destroying the eutectic carbide. On the other hand, since the adamite material or ductile cast iron of the second outer layer has excellent toughness,
It is easy to ensure good interfacial properties after HIP treatment. Next, examples of suitable components of the ductile cast iron or adamite material forming the second outer layer will be listed, and the reasons for limiting the components will be explained. In addition, the unit is weight %. Suitable ductile cast irons include: C: 3.0-3.8% Ni: 2.0% or less Si: 1.5-3.5% Cr: 1.5% or less Mn: 0.2-1.0% Mo: 0.5% or less P: 0.2% or less Mg: 0.02-0.1% S: 0.06% or less Balance Substantially Fe <Reasons for component limitation> C: 3.0 to 3.8% C is directly involved in the formation of cementite and graphite. If it is less than 3.0%, the amounts of cementite and graphite will be insufficient, the heat crack dispersion effect will be insufficient, and the characteristics of spheroidal graphite cast iron cannot be fully exhibited. However, if the amount is too large, the material becomes brittle, so the upper limit is set at 3.8%. Si: 1.5-3.5% Si influences the amount ratio of cementite and graphite,
If it is less than 1.5%, the amount of cementite becomes excessive. On the other hand, if the content of ductile cast iron exceeds 2.5%, it is not preferable because the graphite content becomes too large and the base structure becomes weak, but the purpose is to prevent Cr from being mixed in from the first outer layer and causing chilling. 3.5%
The following shall apply. Mn: 0.2-1.0% It suppresses the damage caused by S and is effective in increasing hardness. 0.2% or more is required for this purpose, but 1.0%
If it exceeds this value, the material becomes hard and brittle. P: 0.2% or less P makes the material brittle, so it should be 0.2% or less.
Note that since P improves the fluidity of the molten metal and increases wear resistance, the upper limit is 0.2%, and it may be added in an amount of 0.01% or more. S: 0.06% or less Similar to P, S makes the material brittle and also inhibits the spheroidization of graphite, so the content should be 0.06% or less. Ni: 2.0% or less Ni has the effect of improving graphitization and hardenability.
Ni is mixed in from the outer shell even if it is not added, but 2.0%
If it exceeds this, the hardenability will be good and the matrix will become too hard, which is not good in terms of toughness and residual stress. Accordingly
2.0% or less. Cr: 1.5% or less Cr is unavoidably mixed from the first outer layer. 1.5
%, the amount of cementite becomes excessive,
The material becomes brittle. Mo: 0.5% or less Mo has the same effect as Ni, and if it exceeds 0.5%, the second outer layer becomes too hard, so it should be kept at 0.5% or less as a range that does not cause any actual damage. Mg: 0.02 to 0.1% or less Necessary for graphite spheroidization; less than 0.02% causes poor spheroidization. On the other hand, if it exceeds 1.0%, casting defects are likely to occur and the material becomes brittle due to an increase in the amount of cementite. Suitable adamite materials include: C: 1.0-2.5% Ni: 1.5% or less Si: 0.5-1.5% Cr: 1.5% or less Mn: 0.5-1.5% Mo: 0.5% or less P: 0.1% or less Ti: 0.1% or less S: 0.1% or less The balance is real <Reason for limiting the composition> C: 1.0 to 2.5% When C is less than 1.0%, the casting temperature of the second outer layer becomes high, and the high chromium cast iron of the first outer layer is easily melted, and the Cr% of the second outer layer increases. further increases, and the toughness of the second outer layer deteriorates. Moreover, when C exceeds 2.5%, carbides increase, the toughness of the second outer layer deteriorates, and the second outer layer loses its significance. Si: 0.5-1.5% Si has a deoxidizing effect on the molten metal, and 0.5% or more is necessary; if it exceeds 1.5%, it becomes brittle and causes deterioration of the mechanical properties of the second outer layer. Mn: 0.5-1.5% Mn also has the same effect as Si, and
At least 0.5% is necessary to convert into MnS and eliminate the adverse effects of S. If it exceeds 1.5%, the effect will be saturated and the mechanical properties will deteriorate, so the content is set in the range of 0.5 to 1.5%. P: 0.1% or less P increases the fluidity of the molten metal but reduces the toughness of the material, so it should be kept at 0.1% or less. S: 0.1% or less S causes no actual damage as it makes the roll material brittle.
0.1% or less. Ni: 1.5% or less Even if Ni is not added, it will be mixed in from the first outer layer.
Although the Ni content is 0.3% or more, the content of Ni up to 1.5% is not a problem. However, if it exceeds 1.5%, the hardenability improves, but the base becomes too hard, which is bad from the standpoint of toughness and residual stress.
Therefore, it should be 1.5% or less. Cr: 1.5% or less If it exceeds 1.5%, mechanical properties, especially toughness, deteriorate and become brittle. Therefore, the Cr content of the molten metal for the second outer layer needs to be 1% or less in consideration of the Cr content of the first outer layer being mixed into the second outer layer. Mo: 0.5% or less No has the same effect as Ni, and if it exceeds 0.5%, the second outer layer will become too hard, so it should be considered as a range without actual damage.
0.5% or less. Ti: 0.1% or less Ti is effective for deoxidizing during casting, but if it exceeds 0.1%, the molten metal becomes overoxidized and the fluidity of the molten metal decreases, so it should be kept at 0.1% or less. Composite ring roll 1 with a single outer layer as described above
The multi-layered composite ring roll 11 may be used as it is without being assembled on a shaft, as in the case of a block mill, but it may be used as an assembly roll by assembling it on a shaft as shown in FIGS. 4 to 6. That is, as shown in FIG. 4, the annular convex portion 22 is integrally formed on the outer periphery of the central portion of the shaft 21, which is shrink-fitted and fixed, or as shown in FIGS. 5 and 6, the composite ring roll is fixed to the shaft 23. 1 and spacer ring 24 or/
It is also possible to shrink-fit the terminal ring 25 and use it as an assembly roll. Although the composite ring roll 1 shown in FIGS. 4 to 6 has a single layer, it is of course possible to use a composite ring roll with multiple layers. Also, composite ring roll 1,1
It goes without saying that the composite ring rolls can be assembled to one shaft by forming a rolling mill so that one composite ring roll or two or more composite ring rolls can be assembled. Further, the shaft material is generally made of a steel material that is strong and can be fixed by welding, but it goes without saying that if the rolling load is small, it may be made of cast iron material such as ductile cast iron. Next, specific examples will be listed and explained. <Example 1> Manufacturing example of a composite ring roll with a single outer layer having an outer diameter D ₁ = φ330 mm, an inner diameter D ₃ = φ160 mm, an outer layer/inner layer boundary diameter D ₂ = φ240 mm, and a width of 200 mm (1) Table 1 shows High chromium cast iron and low C steel with the outer layer composition shown: C: 0.24%, Si: 0.10%, Mn: 0.42%, the balance being substantially Fe (common to Examples 1-1 and 1-2)
I made a material ring with the following dimensions. The outer layer material ring was centrifugally cast using the high chromium cast iron shown in Table 1, and then modified to the dimensions shown below.・Outer layer material ring D ₁ ′ = φ306, D ₂ = φ240, width 205mm ・Inner layer material ring D ₂ = φ240, D ₃ ′ = φ155, width 205mm

[Table] Note Unit weight%
The remainder is essentially Fe
(2) The outer layer and inner layer material rings were fitted together and subjected to HIP treatment at a pressure of 200 Kg/cm ² and a temperature of 1040° C., and the two were diffusion bonded to obtain a composite material. (3) Thereafter, the composite material was subjected to quenching and tempering heat treatment, and then a composite ring roll was obtained by machining. The hardness of the outer layer of the product is as follows in Example 1-1.
Hs75, Hs81 in Example 1-2, and the hardness of the inner layer was Hs35. (4) Two of each of the composite ring rolls were prepared and fixed to the shaft by shrink fitting as shown in FIG. 4 to obtain assembled rolls for rolling steel bars. <Example 2> Manufacturing example of a composite ring roll with a multilayer outer layer of outer diameter D ₁ = φ330 mm, inner diameter D ₃ = φ160 mm, outer layer/inner layer boundary diameter D ₂ = φ240 mm, width 200 mm (1) Table 2 shows Examples 2-1, 2-2, 2 described
- After centrifugally casting the first outer layer of high chromium cast iron No. 3, and after the molten metal of the first outer layer is completely solidified, pouring the molten metal of the second outer layer shown in the same table onto the inner surface of the first outer layer by centrifugal force casting, The inner surface of the first outer layer was melted to completely weld the first outer layer and the second outer layer. still,
The Cr content (wt%) of the second outer layer after solidification and the boundary diameter Do between the first outer layer and the second outer layer were as shown in Table 3.

【table】

[Table] (2) A material ring was manufactured by modifying the outer layer material in which the first outer layer and the second outer layer were integrally cast and the inner layer material of low C steel shown in Table 4 below. Material ring dimensions (common to all examples) ・Outer layer material ring D ₁ ′ = φ335, D ₂ = φ240, width 205 mm ・Inner layer material ring D ₂ = φ240, D ₃ ′ = φ155, width 205 mm

[Table] (3) The outer layer and inner layer material rings were fitted together and subjected to HIP treatment at a pressure of 200 Kg/cm ² and a temperature of 1100°C to diffusion bond the two to obtain a composite material. (4) After that, the composite material was subjected to quenching and tempering heat treatment, and then a composite ring roll was obtained by machining. The hardness of the outer layer (first outer layer) and inner layer of the product was as shown in Table 5 below.

[Table] (Effects of the Invention) As explained above, the composite ring roll according to the present invention has an outer layer made of high chromium cast iron containing 0.25 to 1.0% P and having extremely excellent wear resistance and seizure resistance. Since the inner layer is made of a strong steel material, it can be used as a roll for rolling steel wire rods, bars, etc., especially as a roll for a finishing mill, at low cost, and also has an excellent lifespan. Furthermore, since the outer layer and the inner layer are diffusion bonded by HIP processing, it is possible to prevent Cr from entering the inner layer from the outer layer made of a high chromium material, and the toughness of the inner layer is not deteriorated. Further, the outer layer of the composite ring roll according to another invention is composed of the first outer layer made of the high chromium material with excellent wear resistance and seizure resistance, and the second outer layer made of ductile cast iron or adamite material. Therefore, both can be easily integrated by casting, and the first
Even if the outer layer is formed of high chromium cast iron containing a large amount of high hardness eutectic chromium carbide and a Cr:10 to 25% P content, the first outer layer and the inner layer are not directly diffusion bonded, and the second outer layer and the inner layer are Because they are diffusion bonded, the interface properties of the bonded surface between the outer layer and the inner layer are extremely good, the strength of the interface is extremely high, and there is no possibility of peeling at the interface.
It is possible to prevent breakage as much as possible. In addition, if the composite ring roll of the present invention whose inner layer is made of a tough material is applied to an assembly roll, it can be assembled to the shaft at low cost using a simple shrink fit method, welding, screws, bolts, etc. Furthermore, the shaft can be reused.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a composite ring roll according to the present invention having a single outer layer, FIG. 2 1 and 2 are sectional views of a material ring, and FIG. 3 is a cross-sectional view of a composite ring roll according to the present invention having a multilayer outer layer. 4 to 6 are partial sectional views of an assembled roll to which the composite ring roll according to the present invention is applied, and FIG. 7 is a sectional view of a conventional ring roll. 1, 11... Composite ring roll, 2, 12...
Outer layer, 12a...first outer layer, 12b...second outer layer, 3...inner layer.

Claims (1)

[Claims] 1% by weight: C: 2.0-4.0% Ni: 0.5-2.0% Si: 0.5-1.5% Cr: 10-25% Mn: 0.5-1.5% Mo: 0.5-3.0% P: 0.25 ~1.0% S: An outer layer made of high chromium cast iron with an alloy component of 0.1% or less and the remainder substantially Fe, and an inner layer made of steel are diffusion bonded by hot isostatic pressing. A composite ring roll featuring 2. The composite ring roll according to claim 1, wherein the inner layer is made of low carbon, low alloy steel comprising a ferrite base. 3 In weight%, C: 2.0-4.0% Ni: 0.5-2.0% Si: 0.5-1.5% Cr: 10-25% Mn: 0.5-1.5% Mo: 0.5-3.0% P: 0.25-1.0% S: 0.1 % or less Nb, V: The composition of one or two types is an alloying component of 1.0% or less, and the remainder is substantially Fe.The outer layer is made of high chromium cast iron and the inner layer is made of steel under hot isostatic pressure. A composite ring roll characterized by being diffusion bonded by pressure. 4. The composite ring roll according to claim 3, wherein the inner layer is made of low carbon, low alloy steel comprising a ferrite base. 5% by weight: C: 2.0-4.0% Ni: 0.5-2.0% Si: 0.5-1.5% Cr: 10-25% Mn: 0.5-1.5% Mo: 0.5-3.0% P: 0.25-1.0% S: 0.1 A first outer layer formed of high chromium cast iron with an alloy component of % or less and the remainder substantially Fe, and a second outer layer integrally formed by casting ductile cast iron or adamite material on the inner surface of the first outer layer. 1. A composite ring roll comprising: a cylindrical outer layer; an inner layer disposed inside the outer layer and made of steel; and the second outer layer are diffusion bonded by hot isostatic pressing. 6 The second outer layer is expressed in weight%: C: 3.0 to 3.8% Ni: 2.0% or less Si: 1.5 to 3.5% Cr: 1.5% or less Mn: 0.2 to 1.0% Mo: 0.5% or less P: 0.2% or less Mg: 0.02 to 0.1% S: 0.06% or less The composite ring roll according to claim 5, characterized in that the remainder is ductile cast iron consisting essentially of Fe. 7 The second outer layer has the following properties by weight: C: 1.0-2.5% Ni: 1.5% or less Si: 0.5-1.5% Cr: 1.5% or less Mn: 0.5-1.5% Mo: 0.5% or less P: 0.1% or less Ti: 0.1% or less S: 0.1% or less The composite ring roll according to claim 5, characterized in that the remainder is an adamite material consisting essentially of Fe. 8. The composite ring roll according to claim 5, wherein the inner layer is made of low carbon, low alloy steel comprising a ferrite base. 9 In weight%, C: 2.0-4.0% Ni: 0.5-2.0% Si: 0.5-1.5% Cr: 10-25% Mn: 0.5-1.5% Mo: 0.5-3.0% P: 0.25-1.0% S: 0.1 % or less Nb, V: A first outer layer formed of high chromium cast iron with the total of one or two types being 1.0% or less as an alloying component and the remainder substantially consisting of Fe, and the inner surface of the first outer layer is made of ductile cast iron or A cylindrical outer layer consisting of a second outer layer integrally cast from an adamite material, and an inner layer disposed inside the outer layer and formed from a steel material and the second outer layer are hot isostatically pressed. A composite ring roll characterized by being diffusion bonded by. 10 The second outer layer is as follows in weight%: C: 3.0-3.8% Ni: 2.0% or less Si: 1.5-3.5% Cr: 1.5% or less Mn: 0.2-1.0% Mo: 0.5% or less P: 0.2% or less Mg: 0.02 to 0.1% S: 0.06% or less The composite ring roll according to claim 9, characterized in that the remainder is ductile cast iron consisting essentially of Fe. 11 The second outer layer has the following properties by weight: C: 1.0-2.5% Ni: 1.5% or less Si: 0.5-1.5% Cr: 1.5% or less Mn: 0.5-1.5% Mo: 0.5% or less P: 0.1% or less Ti: 10. The composite ring roll according to claim 9, wherein S: 0.1% or less; the remainder being an adamite material consisting essentially of Fe. 12 Claim 9, characterized in that the inner layer is a low-carbon, low-alloy steel consisting of a ferrite base.
Composite ring roll as described in section.