Method of manufacturing a graphite steel roller ring

Abstract

This invention provides a method for manufacturing graphite steel roll rings. The centrifugal bimetallic composite graphite steel roll ring includes an outer ring and an inner ring. The outer ring contains a plurality of spherical graphite dots uniformly dispersed within it. The inner ring is located on the inner wall of the outer ring, and the outer ring and the inner ring are integrally cast. The centrifugal bimetallic composite graphite steel roll ring provided by this invention has multiple graphite dots in its outer ring composition. These graphite dots transform the outer ring into graphite steel. The graphite dots can inhibit the propagation of cracks caused by thermal fatigue during the rolling process, increase the steel throughput in a single rolling pass, reduce crack formation, decrease the amount of fatigue layer repair required after rolling, reduce roll wear, and save processing costs.

Description

Technical Field

[0001] This invention belongs to the field of centrifugal casting technology, specifically relating to a method for manufacturing graphite steel roller rings. Background Technology

[0002] Roll rings are wear-resistant components of profile rolling mill rolls, specifically for rolled steel sections with perforations. The roll rings are located in the middle of the roll body.

[0003] During the rolling process of structural steel, the horizontal roll ring has a large contact area with the hot steel. At the same time, due to the limited cooling capacity on site, the roll ring is prone to thermal fatigue. In particular, the part where the horizontal roll ring contacts the structural steel is prone to thermal fatigue cracks. In severe cases, this can cause the roll ring to break off, affecting the appearance quality of the structural steel. At the same time, the workload of crack repair is large, which increases roll wear, resulting in high production costs and affecting the output of structural steel rolling. Summary of the Invention

[0004] This invention provides a method for manufacturing graphite steel roll rings, aiming to solve the technical problem of thermal fatigue cracks caused by insufficient cooling of the roll rings during the rolling process in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, a centrifugal bimetallic composite graphite steel roller ring is provided, comprising an outer ring and an inner ring, wherein a plurality of spherical graphite dots are uniformly dispersed in the outer ring, and the inner ring is disposed on the inner wall of the outer ring, and the outer ring and the inner ring are integrally composite cast.

[0007] In conjunction with the first aspect, in one possible implementation, the wall thickness ratio of the outer ring to the inner ring is 2:1.

[0008] In conjunction with the first aspect, in one possible implementation, the chemical composition of the outer ring and the mass fraction of each component are as follows: C: 1.90–2.1%, Si: 1.40–1.60%, Mn: 0.80–1.0%, P≤0.035%, S≤0.03%, Cr: 1.8%–2.0%, Mo: 0.3–0.5%, Ni: 1.0–1.5%, V: 0.2–0.4%, with the balance being Fe.

[0009] In conjunction with the first aspect, in one possible implementation, the chemical composition of the inner ring and the mass fraction of each component are: C: 1.3-1.5%, Si: 1.6-1.8%, Mn: 0.8-1.0%, P≤0.035%, S≤0.03%, Cr≤0.2%, with the balance being Fe.

[0010] The centrifugal bimetallic composite graphite steel roll ring provided by this invention, compared with the prior art, has multiple graphite dots in the outer ring composition in addition to various alloys that form carbides to ensure wear resistance. The graphite dots make the outer ring into graphite steel. The graphite dots can inhibit the crack propagation caused by thermal fatigue during the rolling process of the steel roll ring, increase the steel throughput of the steel roll ring in a single rolling, reduce the number of cracks, reduce the amount of fatigue layer repair after rolling, reduce roll wear, and save processing costs.

[0011] Secondly, this application provides a method for manufacturing a graphite steel roller ring, used to manufacture a centrifugal bimetallic composite graphite steel roller ring as described in any of the possible implementations above, comprising the following steps:

[0012] S1: The raw materials for the outer ring and the raw materials for the inner ring are smelted separately to form molten steel for the outer ring and molten steel for the inner ring. Silicon is added to the raw materials for the outer ring to form graphite dots in the molten steel for the outer ring.

[0013] S2: Molten steel is poured into the centrifuge to form a prefabricated outer layer;

[0014] S3: Molten steel is poured into the inner ring inside the prefabricated outer layer to form a prefabricated roll ring;

[0015] S4: Pre-fabricated roller rings undergo diffusion annealing treatment;

[0016] S5: Heat-treat the prefabricated roller ring to form the roller ring.

[0017] In conjunction with the second aspect, in one possible implementation, step S2 specifically includes: pouring molten steel into the outer ring in batches within a centrifuge, with each pour having the same thickness of molten steel.

[0018] In conjunction with the second aspect, in one possible implementation, the pouring temperature of the molten steel in the inner ring is higher than that of the molten steel in the outer ring.

[0019] In conjunction with the second aspect, in one possible implementation, step S1 specifically includes: smelting the raw materials for the outer ring and the raw materials for the inner ring separately, so that the chemical composition and mass fraction of the outer ring molten steel are controlled at C: 1.90–2.1%, Si: 1.40–1.60%, Mn: 0.80–1.0%, P≤0.035%, S≤0.03%, Cr: 1.8%–2.0%, Mo: 0.3–0.5%, Ni: 1.0–1.5%, V: 0.2–0.4%, with the balance being Fe;

[0020] The chemical composition and mass fraction of the molten steel in the inner ring are controlled as follows: C: 1.3-1.5%, Si: 1.6-1.8%, Mn: 0.8-1.0%, P≤0.035%, S≤0.03%, Cr≤0.2%, with the balance being Fe;

[0021] Inoculation treatment was carried out by adding 0.8% SiCaBa inoculant to the outer and inner rings of molten steel, respectively.

[0022] Rare earth elements were added to the outer and inner rings of molten steel for modification treatment.

[0023] In conjunction with the second aspect, in one possible implementation, step S3 specifically includes:

[0024] Centrifuge the molten steel in the outer ring at a speed of 450-550 rpm for 20-30 minutes.

[0025] Molten steel was poured into the inner ring in stages, with a time interval of 2 to 3 minutes between each two pours.

[0026] In conjunction with the second aspect, in one possible implementation, step S5 further includes performing roll ring flaw detection.

[0027] The graphite steel roll ring manufacturing method provided by this invention, compared with the prior art, involves first pouring molten steel for the outer ring, followed by pouring molten steel for the inner ring. Silicon is incorporated into the outer ring molten steel, generating graphite dots before casting, thus improving the roll ring's performance. During steel rolling, these graphite dots prevent thermal fatigue cracks in the roll ring, reducing the amount of repair required. The sequential pouring of the outer and inner ring molten steel ensures a metallurgical bond between the two rings, preventing them from fusing together and guaranteeing the high hardness of the outer ring and the high toughness of the inner ring. Heat treatment of the steel roll ring eliminates casting stress and increases the steel throughput. The roll ring produced by this method has multiple graphite dots in the outer ring, transforming it into graphite steel. These graphite dots inhibit crack propagation caused by thermal fatigue during rolling, increasing the steel throughput per rolling pass, reducing crack formation, decreasing fatigue layer repair after rolling, lowering roll wear, and saving processing costs. Detailed Implementation

[0028] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is actually illustrative only and is in no way intended to limit this application or its application or use. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations.

[0032] It should be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "joining," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Additionally, "multiple" and "several" mean two or more, unless otherwise explicitly specified.

[0034] The centrifugal bimetallic composite graphite steel roller ring provided by the present invention will now be described. The centrifugal bimetallic composite graphite steel roller ring includes an outer ring and an inner ring. The outer ring has a plurality of spherical graphite dots uniformly dispersed inside it. The inner ring is located on the inner wall of the outer ring, and the outer ring and the inner ring are integrally cast into a composite shape.

[0035] It should be noted that the outer ring and the inner ring will be joined together during centrifugal casting, making the outer ring and the inner ring a whole.

[0036] It should be noted that graphite dots are spherical graphite blocks, and the spherical structure can prevent the formation of thermal fatigue cracks.

[0037] It should be noted that the outer ring and the inner ring will not be fused together. The outer ring and the inner ring have different compositions. The outer ring has high hardness, while the inner ring has high toughness. The outer ring and the inner ring are organically combined and each retains its original properties. The outer ring is used to contact the structural steel, and the inner ring is used to connect with the steel roller.

[0038] The centrifugal bimetallic composite graphite steel roll ring provided in this embodiment, compared with the prior art, divides the steel roll ring into an inner ring and an outer ring. The outer ring contains multiple graphite dots, which make the outer ring into graphite steel. The graphite dots can inhibit the crack propagation caused by thermal fatigue during the rolling process of the steel roll ring, increase the steel throughput of the steel roll ring in a single rolling, reduce the number of cracks, reduce the amount of fatigue layer repair after rolling, reduce roll consumption, and save processing costs.

[0039] In some embodiments, the wall thickness ratio of the outer ring to the inner ring is 2:1. The function of the outer ring is to contact the hot steel and protect the inner ring. The outer ring requires high hardness and a high level of protection. The thickness of the outer ring is twice that of the inner ring, which can improve the protection effect on the inner ring.

[0040] In some embodiments, the chemical composition of the outer ring and the mass fraction of each component are as follows: C: 1.90–2.1%, Si: 1.40–1.60%, Mn: 0.80–1.0%, P≤0.035%, S≤0.03%, Cr: 1.8%–2.0%, Mo: 0.3–0.5%, Ni: 1.0–1.5%, V: 0.2–0.4%, with the balance being Fe.

[0041] Analysis revealed that in the outer ring molten steel, the carbide content was high when the silicon content was 0-2.0% and the manganese content was greater than 1%; conversely, when the manganese content was less than or equal to 0.3%, the ferrite content in the matrix increased. Therefore, to maintain the stability of the outer ring molten steel, the Mn content should be controlled within the range of 0.4-1.0%.

[0042] The principle of this embodiment is that silicon acts as a catalyst, assisting carbon (C) in transforming into graphite, thus transforming the outer ring into graphite steel. High-carbon steel undergoes thorough deoxidation during smelting, and the graphitization of cementite in the steel is induced during high-temperature annealing, resulting in the formation of blocky graphite in the molten steel. This type of steel is called graphite steel, possessing the properties of both steel and iron, exhibiting high resistance to hot cracking, and reducing the probability of thermal fatigue cracks forming in the outer ring.

[0043] This embodiment provides the chemical composition and mass fraction of each component of the outer ring. Silicon (Si) acts as a catalyst, enabling carbon (C) to be fully deoxidized during smelting, producing blocky graphite in the molten steel. This ensures that the outer ring cast from the molten steel is graphite steel, improving its resistance to hot cracking. The matrix structure formed after the outer ring is cast and annealed is pearlite. The addition of Cr improves the stability of the pearlite structure. The addition of Mo avoids temper brittleness and improves the structural strength of the outer ring. The addition of Ni gives the outer ring a certain degree of toughness. The S content is ≤0.03%, reducing the impact on the graphite morphology, causing the graphite in the molten steel to become spherical. The outer ring provided in this embodiment is made of alloy material, featuring high hardness and high resistance to hot cracking. The graphite dots give the outer ring high-strength fatigue resistance, reducing the probability of thermal fatigue cracks when in contact with hot steel, improving the rolling quality of the section steel, and reducing the maintenance cost of the rolls.

[0044] In some embodiments, the chemical composition of the inner ring and the mass fraction of each component are: C: 1.3-1.5%, Si: 1.6-1.8%, Mn: 0.8-1.0%, P≤0.035%, S≤0.03%, Cr≤0.2%, balance Fe.

[0045] The chemical composition and mass fraction of each component of the inner ring provided in this embodiment are such that the cast inner ring has high toughness.

[0046] As a specific embodiment of the graphite steel roller ring in this example, the graphite steel roller ring includes an outer ring and an inner ring; wherein, the chemical composition and mass fraction of each component of the outer ring are C: 2%, Si: 1.60%, Mn: 0.90%, P≤0.035%, S≤0.03%, Cr: 2.0%, Mo: 0.5%, Ni: 1.5%, V: 0.4%, with the balance being Fe; the chemical composition of the inner ring is C: 1.4%, Si: 1.7%, Mn: 1.0%, P≤0.035%, S≤0.03%, Cr≤0.2%, with the balance being Fe.

[0047] Based on the same inventive concept, this application also provides a method for manufacturing graphite steel roller rings, used to manufacture centrifugal bimetallic composite graphite steel roller rings as described in any of the above embodiments. The method for manufacturing graphite steel roller rings includes the following steps: S1: smelting the raw materials for the outer ring and the raw materials for the inner ring separately to form molten steel for the outer ring and molten steel for the inner ring, wherein silicon is added to the raw materials for the outer ring to form graphite dots in the molten steel for the outer ring; S2: pouring the molten steel for the outer ring in a centrifuge to form a prefabricated outer layer; S3: pouring the molten steel for the inner ring into the prefabricated outer layer to form a prefabricated roller ring; S4: subjecting the prefabricated roller ring to diffusion annealing treatment; S5: subjecting the prefabricated roller ring to heat treatment to form a roller ring.

[0048] It should be noted that the heat treatment in S5 includes quenching and tempering the prefabricated roll rings. The quenching temperature is higher than the tempering temperature, which improves the performance of the roll rings.

[0049] It should be noted that silicon can promote the graphitization of carbon elements, transforming some of the carbon in the raw materials into spherical graphite, which in turn transforms the outer ring into graphite steel, thereby improving the outer ring's resistance to thermal cracking.

[0050] The graphite steel roll ring manufacturing method provided in this embodiment, compared with the prior art, involves first pouring molten steel for the outer ring, followed by pouring molten steel for the inner ring. Silicon is incorporated into the outer ring molten steel, generating graphite dots within it before casting, thus improving the roll ring's performance. During steel rolling, these graphite dots prevent thermal fatigue cracks in the roll ring, reducing the amount of repair required. The sequential pouring of the outer and inner ring molten steel ensures a metallurgical bond between the two rings, preventing them from fusing together and guaranteeing both the high hardness of the outer ring and the high toughness of the inner ring. Heat treatment of the steel roll ring eliminates casting stress and increases the steel throughput. The roll ring produced by this method has multiple graphite dots in its outer ring composition, transforming it into graphite steel. These graphite dots inhibit crack propagation caused by thermal fatigue during rolling, increasing the steel throughput per rolling pass, reducing crack formation, decreasing the amount of fatigue layer repair required after rolling, reducing roll wear, and saving processing costs.

[0051] In some embodiments, step S2 specifically includes: pouring molten steel for the outer ring in batches within a centrifuge, with each batch containing the same thickness of molten steel for the outer ring. The outer ring is thicker than the inner ring. Pouring the molten steel in batches allows the outer ring's forming thickness to gradually and steadily increase, avoiding the need to add all the molten steel at once, which would result in different rotation speeds for the inner and outer layers, affecting the outer ring's forming quality. Adding the same thickness of molten steel each time ensures that the rotation speed of the outer ring's molten steel is the same for adjacent pours, improving the quality of the outer ring. A smaller amount of molten steel poured each time makes it easier to control the pouring quality, resulting in finer crystals in the outer ring and improved wear resistance.

[0052] In practice, the molten steel for the outer ring is poured in two stages.

[0053] In some embodiments, the casting temperature of the inner ring molten steel is higher than that of the outer ring molten steel. The higher casting temperature of the inner ring prevents the inner ring molten steel from fusing with the outer ring, ensuring the inner ring's toughness. During centrifugal casting, the higher casting temperature of the inner ring molten steel allows the outer layer of the inner ring and the inner layer of the outer ring to bond together, improving the overall structural strength of the roll ring.

[0054] In some embodiments, step S1 specifically includes: smelting the raw materials for the outer ring and the raw materials for the inner ring separately, so that the chemical composition and mass fraction of the outer ring molten steel are controlled at C: 1.90-2.1%, Si: 1.40-1.60%, Mn: 0.80-1.0%, P≤0.035%, S≤0.03%, Cr: 1.8%-2.0%, Mo: 0.3%-0.5%, Ni: 1.0%-1.5%, V: 0.2%-0%. 0.4%, balance Fe; the chemical composition and mass fraction of the inner ring molten steel are controlled at C: 1.3-1.5%, Si: 1.6-1.8%, Mn: 0.8-1.0%, P≤0.035%, S≤0.03%, Cr≤0.2%, balance Fe; 0.8% SiCaBa inoculant is added to the outer and inner ring molten steel respectively for inoculation treatment; rare earth elements are added to the outer and inner ring molten steel respectively for modification treatment.

[0055] In this embodiment, raw materials are first smelted to form outer and inner ring molten steel. The addition of an inoculant transforms the graphite blocks in the outer ring molten steel into spherical or worm-like free graphite, further improving the strength and toughness of the formed outer ring, i.e., spheroidal graphite cast steel. The fatigue strength of spheroidal graphite cast steel is 50% greater than that of cast iron and steel without alloying and inoculant. At 550°C, the number of cycles until cracks appear in rolls made of spheroidal graphite cast steel, ordinary cast steel, and cast iron are 119, 11, and 21, respectively; while at 600°C, they are 30, 9, and 7, respectively. The results show that the graphite morphology in the steel matrix has a significant impact on its performance. Spheroidal graphite can hinder the occurrence and propagation of thermal fatigue cracks. When the graphite in the steel is flake-shaped, the number of cycles reaching the point of damage does not exceed 63-121, while the number of cycles for spheroidal graphite cast steel is as high as 865-1883.

[0056] This embodiment provides a method for forming graphite blocks. Inoculants are used to inoculate the outer ring steel, transforming carbon into spherical graphite. Rare earth elements are then added to modify the outer ring steel, improving its quality and ensuring the quality of the cast roll ring. Adding rare earth elements to modify the outer ring steel eliminates network and large blocky carbides, facilitating silicon's catalysis of carbon into free spherical graphite and increasing the carbon conversion efficiency. The rare earth modification also reduces the content of gaseous and impurity elements in the material, improving its thermal fatigue resistance and resulting in uniform hardness on the outer circumference of the cast outer ring.

[0057] In some embodiments, step S3 specifically includes: centrifuging the outer ring molten steel continuously at a speed of 450-550 rpm for 20-30 minutes; pouring the inner ring molten steel in multiple stages, with a time interval of 2-3 minutes between two adjacent pours of the inner ring molten steel. This embodiment describes the pouring method of the inner ring molten steel. By dividing the inner ring molten steel into multiple pours, the amount of inner ring molten steel poured each time is small, and the thickness of the inner ring wall formed by a single pour is thin, which can ensure the toughness of the inner ring. The interval between two adjacent pours of the inner ring molten steel prevents the prefabricated outer layer from fusing with the inner ring molten steel, causing the alloy of the outer ring to fuse with the alloy of the inner ring, which would affect the toughness of the inner ring; it can also ensure the composite quality of the inner and outer rings.

[0058] In practice, the inner ring of molten steel is poured in two stages, with an interval of 2 to 3 minutes between the two stages. The time interval between the inner ring of molten steel and the outer ring of molten steel is 20 to 30 minutes, ensuring that the outer ring of molten steel becomes the precast outer layer when the inner ring of molten steel is poured.

[0059] In some embodiments, step S5 is followed by roller ring flaw detection. Roller ring flaw detection can inspect the quality and hardness of the roller ring, as well as whether there are defects, thereby improving production quality.

[0060] The following is one embodiment of the roller ring:

[0061] The alloy composition of the outer ring and the weight percentage of each alloy component are as follows: C: 1.90-2.1%, Si: 1.40-1.60%, Mn: 0.80-1.0%, P≤0.035%, S≤0.03%, Cr: 1.8%-2.0%, Mo: 0.3%-0.5%, Ni: 1.0%-1.5%, V: 0.2%-0.4%, with the remainder being Fe and unavoidable impurities;

[0062] The alloy composition of the inner ring and the weight percentage of each alloy component are as follows: C: 1.3-1.5%, Si: 1.6-1.8%, Mn: 0.8-1.0%, P≤0.035%, S≤0.03%, Cr≤0.2%, with the remainder being Fe and unavoidable impurities;

[0063] The outer and inner rings are smelted separately. The outer ring is made from high-quality scrap steel mixed with alloys and smelted in a medium-frequency furnace at a temperature of 1580–1620℃. Before tapping, a slag remover is added to the furnace for slag formation. The core is made from high-quality scrap steel mixed with alloys and smelted at a temperature of 1620–1660℃. During tapping of both the outer and inner ring steels, 0.8% SiCaBa inoculant is added to the ladle to inoculate the steel, promoting the formation of graphite and improving fatigue strength. The steel is then modified using rare earth modifiers at a rate of 0.2% of the total steel volume to refine the grains and improve wear resistance.

[0064] The outer and inner layers are organically combined through process design. First, the outer ring of the roll ring is cast at a temperature of 1430–1460℃. During casting, the centrifuge speed is calculated to be 450–550 rpm. After the outer ring is cast, it is centrifuged at a constant speed for 20–30 minutes. Then, the inner ring is cast at a temperature 80–100℃ higher than the outer ring. To ensure toughness and support, the inner ring has a smaller alloy content during smelting and a higher casting temperature. To prevent the outer ring alloy from incorporating into the inner ring and reducing its toughness, a method of interrupting the flow of 30mm thick molten steel for 2–3 minutes is used. This prevents the outer ring alloy from incorporating into the inner ring while ensuring good bonding between the inner and outer layers, maintaining the high hardness of the outer ring and the high toughness of the inner layer. After the steel is cast, the centrifuge runs for 2–2.5 hours, then the centrifuge is stopped, the cooling mold is opened, and the precast roll ring is removed.

[0065] Precast roller rings undergo high-temperature diffusion annealing in a kiln. The diffusion annealing temperature is 1050–1060℃, and the holding time is 13–15 hours. After the holding time, the rings are cooled in the furnace.

[0066] The precast roller ring is heat-treated by quenching and tempering. The quenching temperature is 930-960℃ and the quenching holding time is 10-18 hours. The tempering temperature is 450-500℃, and the microstructure has a certain bainitic structure. The hardness of the roller ring is increased to HSD63-68, which improves the wear resistance. The tempering time is 20-25 hours to obtain the finished roller ring.

[0067] The finished roller rings undergo performance testing to ensure they are free of defects in appearance. The outer ring hardness is HSD 63 / 68, and the hardness difference between the outer and inner rings (160-180mm) is ≤5HSD. The inner ring hardness is HSD 45 / 50. The inner layer tensile strength is ensured to be 550-650MPa, and flaw detection conforms to the GB / T1503-2008 flaw detection standard.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a graphite steel roller ring, used to manufacture a centrifugal bimetallic composite graphite steel roller ring, the centrifugal bimetallic composite graphite steel roller ring comprising an outer ring and an inner ring, wherein a plurality of spherical graphite dots are uniformly dispersed within the outer ring, and the inner ring is disposed on the inner wall of the outer ring, and the outer ring and the inner ring are integrally cast; the wall thickness ratio of the outer ring to the inner ring is 2:1; the chemical composition and mass fraction of each component of the outer ring are: C: 1.90~2.1%, Si: 1.40~1.60%, Mn:

0. The chemical composition and mass fraction of the inner ring are: C: 1.3-1.5%, Si: 1.6-1.8%, Mn: 0.8-1.0%, P≤0.035%, S≤0.03%, Cr: 1.8%-2.0%, Mo: 0.3-0.5%, Ni: 1.0-1.5%, V: 0.2%-0.4%, balance Fe; characterized in that, Includes the following steps: S1: The raw materials for the outer ring and the inner ring are smelted separately to form outer ring molten steel and inner ring molten steel. The casting temperature of the inner ring molten steel is higher than that of the outer ring molten steel. Silicon is added to the raw materials for the outer ring to form graphite dots in the outer ring molten steel. 0.8% SiCaBa inoculant is added to both the outer and inner ring molten steel for inoculation treatment. Rare earth elements are added to both the outer and inner ring molten steel for modification treatment. S2: Pour the outer ring of molten steel in batches in a centrifuge. The thickness of the outer ring of molten steel is the same each time it is poured to form a prefabricated outer layer. The pouring temperature of the outer ring of molten steel is 1430~1460℃. The centrifuge speed is 450~550 rpm during pouring. After the outer ring of molten steel is poured, continue to centrifuge at a constant speed for 20~30 minutes. S3: Pour molten steel into the inner ring in stages within the precast outer layer to form a precast roller ring. The time interval between two adjacent pours of molten steel into the inner ring is 2 to 3 minutes. S4: The prefabricated roller ring undergoes diffusion annealing at a temperature of 1050~1060℃ and a holding time of 13~15 hours. S5: The prefabricated roller ring is heat-treated by quenching and tempering. The quenching temperature is 930~960℃ and the quenching holding time is 10~18 hours. The tempering temperature is 450~500℃ to form the roller ring.

2. The method for manufacturing graphite steel roller rings as described in claim 1, characterized in that, Step S5 is followed by roller ring flaw detection.