Centrifugal bimetal composite graphite steel roll collar and manufacturing method thereof

Abstract

The invention provides a centrifugal bimetal composite graphite steel roll collar and a manufacturing method thereof.The centrifugal bimetal composite graphite steel roll collar comprises an outer ring and an inner ring, a plurality of spherical graphite points are evenly dispersed in the outer ring, the inner ring is arranged on the inner wall of the outer ring, and the outer ring and the inner ring are integrally formed in a composite casting mode. According to the centrifugal bimetal composite graphite steel roller ring, the multiple graphite points are arranged in the components of the outer ring, the outer ring is changed into graphite steel through the graphite points, the graphite points can restrain crack propagation generated by thermal fatigue in the rolling process of the steel roller ring, the single-time rolling steel passing amount of the steel roller ring is increased, few cracks are generated, the fatigue layer repairing amount of the rolled roller ring is reduced, and the service life of the roller ring is prolonged. Roll consumption can be reduced, and machining cost is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of centrifugal casting, and in particular relates to a centrifugal bimetallic composite graphite steel roller ring and a manufacturing method thereof. Background Art

[0002] The roller ring is a wear-resistant part of the profile roller body for rolling profile steel with holes. The roller ring is located in the middle of the roller body.

[0003] During the steel section rolling process, the horizontal roller ring has a large contact area with the hot steel. At the same time, due to the limitation of the on-site cooling capacity, the roller ring is very prone to thermal fatigue, especially the contact area between the horizontal roller ring and the steel section, which is very prone to thermal fatigue cracks. In severe cases, it causes the roller ring to fall off, affecting the appearance quality of the steel section. At the same time, the workload of crack repair is large, which increases the roller consumption, resulting in high production costs and affecting the output of steel section rolling. Summary of the invention

[0004] The embodiment of the present invention provides a centrifugal bimetallic composite graphite steel roller ring and a manufacturing method thereof, aiming to solve the technical problem in the prior art that the roller ring generates thermal fatigue cracks due to insufficient cooling of the roller ring during the rolling process.

[0005] To achieve the above object, the technical solution adopted by the present invention is: In a first aspect, a centrifugal bimetallic composite graphite steel roller ring and a manufacturing method thereof are provided, comprising an outer ring and an inner ring, wherein a plurality of spherical graphite points are evenly dispersed in the outer ring, the inner ring is arranged on the inner wall of the outer ring, and the outer ring and the inner ring are integrally composite cast.

[0006] In combination with the first aspect, in a possible implementation, the wall thickness ratio of the outer ring and the inner ring is 2:1.

[0007] In combination with the first aspect, in a possible implementation method, the chemical composition of the outer ring and the mass fraction of each component are: 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%, and the remainder is Fe.

[0008] In combination with the first aspect, in a 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%, and the remainder is Fe.

[0009] Compared with the prior art, the centrifugal bimetallic composite graphite steel roller ring provided by the present invention has a plurality of graphite points in the composition of the outer ring in addition to a plurality of alloys that form carbides to ensure wear resistance. The graphite points turn the outer ring into graphite steel. The graphite points can inhibit the propagation of cracks caused by thermal fatigue during the rolling of the steel roller ring, increase the amount of steel rolled in a single time of the steel roller ring, reduce the amount of cracks generated, reduce the amount of fatigue layer repair of the roller ring after rolling, reduce roller consumption, and save processing costs.

[0010] In a second aspect, the present application provides a graphite steel roller ring manufacturing method for manufacturing a centrifugal bimetallic composite graphite steel roller ring as in any of the above possible implementations, comprising the following steps: S1: smelting the raw materials of the outer ring and the raw materials of the inner ring respectively to form outer ring molten steel and inner ring molten steel, wherein silicon is added to the raw materials of the outer ring to form graphite points in the outer ring molten steel; S2: pouring molten steel for the outer ring in the centrifuge to form a prefabricated outer layer; S3: pouring molten steel of the inner ring into the prefabricated outer layer to form a prefabricated roller ring; S4: The prefabricated roller ring is subjected to diffusion annealing treatment; S5: heat-treating the prefabricated roller ring to form a roller ring.

[0011] In combination with the second aspect, in a possible implementation, step S2 specifically includes: pouring the outer ring molten steel in batches in the centrifuge, and the thickness of the outer ring molten steel poured each time is the same.

[0012] In combination with the second aspect, in a possible implementation, the pouring temperature of the inner ring molten steel is higher than the pouring temperature of the outer ring molten steel.

[0013] In combination with the second aspect, in a possible implementation, step S1 specifically includes: smelting the raw materials of the outer ring and the raw materials of the inner ring respectively, so that the chemical composition and mass fraction of the outer ring molten steel are controlled within 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%, and the balance Fe; The chemical composition and mass fraction of the inner ring molten steel are controlled within the range of C: 1.3-1.5%, Si: 1.6-1.8%, Mn: 0.8-1.0%, P≤0.035%, S≤0.03%, Cr≤0.2%, and the balance is Fe; Add 0.8% SiCaBa inoculant into the outer ring molten steel and the inner ring molten steel respectively for inoculation treatment; Rare earth is added into the outer ring molten steel and the inner ring molten steel respectively for modification treatment.

[0014] In conjunction with the second aspect, in a possible implementation manner, step S3 specifically includes: The outer ring molten steel is centrifuged continuously at a speed of 450 to 550 revolutions per minute for 20 to 30 minutes; Pour the molten steel into the inner ring in batches, with the time interval between two adjacent pourings of molten steel in the inner ring being 2 to 3 minutes.

[0015] In combination with the second aspect, in a possible implementation, step S5 further includes performing roller ring flaw detection.

[0016] Compared with the prior art, the graphite steel roller ring manufacturing method provided by the present invention first pours the outer ring molten steel, and then pours the inner ring molten steel. The outer ring molten steel is provided with silicon elements, and the outer ring molten steel generates graphite points before casting, which improves the performance of the roller ring. The graphite points can avoid the generation of thermal fatigue cracks in the roller ring during the rolling of the steel section, and reduce the amount of repair of the roller ring; the outer ring molten steel and the inner ring molten steel are poured successively, so that the formed inner ring and the inner ring can be metallurgically bonded and do not fuse with each other, ensuring the high hardness of the outer ring and the high toughness of the inner ring; the steel roller ring is heat-treated to eliminate the casting stress and increase the amount of steel overload of the roller ring. The roller ring manufactured by this method has a plurality of graphite points in the composition of the outer ring, and the graphite points turn the outer ring into graphite steel. The graphite points can inhibit the crack propagation caused by thermal fatigue during the rolling of the steel roller ring, increase the amount of steel overload of the steel roller ring in a single rolling, generate less cracks, reduce the amount of fatigue layer repair of the roller ring after rolling, can reduce roller consumption, and save processing costs. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0019] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0020] Unless otherwise specifically stated, the relative arrangement of the parts and steps set forth in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present application. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the techniques, methods and equipment should be considered as part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation.

[0022] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "install", "connect", "connect", "fix", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In addition, the meaning of "multiple" and "several" is two or more, unless otherwise clearly and specifically defined.

[0025] The centrifugal bimetallic composite graphite steel roller ring provided by the present invention is now described. The centrifugal bimetallic composite graphite steel roller ring comprises an outer ring and an inner ring, wherein a plurality of spherical graphite points are evenly dispersed in the outer ring, the inner ring is arranged on the inner wall of the outer ring, and the outer ring and the inner ring are integrally composite cast.

[0026] It should be noted that the outer ring and the inner ring will be combined during centrifugal casting so that the outer ring and the inner ring form a whole.

[0027] It should be noted that the graphite points are spherical graphite blocks, and the spherical structure can prevent the occurrence of thermal fatigue cracks.

[0028] It should be noted that the outer ring and the inner ring will not fuse, and the compositions of the outer ring and the inner ring are different. The outer ring has high hardness, and the inner ring has high toughness. The outer ring and the inner ring are organically combined, and each maintains its original performance. The outer ring is used to abut against the steel section, and the inner ring is used to connect with the steel roller.

[0029] Compared with the prior art, the centrifugal bimetallic composite graphite steel roller ring and its manufacturing method provided in this embodiment divide the steel rod ring into an inner ring and an outer ring. The outer ring is provided with a plurality of graphite points in its composition. The graphite points turn the outer ring into graphite steel. The graphite points can inhibit the propagation of cracks caused by thermal fatigue during the rolling process of the steel roller ring, increase the amount of steel rolled in a single time of the steel roller ring, reduce the amount of cracks generated, reduce the amount of fatigue layer repair of the roller ring after rolling, reduce roller consumption, and save processing costs.

[0030] 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 with the hot steel and protect the inner ring. The hardness and protection effect of the outer ring are required to be high. The thickness of the outer ring is twice that of the inner ring, which can improve the protection effect of the inner ring.

[0031] In some embodiments, the chemical composition of the outer ring and the mass fraction of each component are: 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%, and the remainder is Fe.

[0032] After analysis, in the outer ring molten steel, when the silicon content is 0-2.0% and the manganese content is greater than 1%, the carbide content is high; on the contrary, when the manganese content is less than or equal to 0.3%, the ferrite content in the matrix structure increases. Therefore, in order to keep the outer ring molten steel in a stable state, the Mn content should be controlled in the range of 0.4-1.0%.

[0033] The principle of this embodiment is that the silicon material acts as a catalyst to assist C to become graphite, so that the outer ring becomes graphite steel. High carbon steel is fully deoxidized during the smelting process, and the high temperature annealing treatment causes the graphitization of cementite in the steel, so that block graphite is produced in the molten steel. The steel at this time is called graphite steel, which has the properties of both steel and iron, has high thermal crack resistance, and reduces the probability of thermal fatigue cracks in the outer ring.

[0034] This embodiment provides the chemical composition of the outer ring and the mass fraction of each component. Silicon Si acts as a catalyst to fully deoxidize carbon C during smelting, produce blocky graphite in molten steel, ensure that the outer ring cast by the outer ring molten steel is graphite steel, and improve the thermal cracking resistance of the outer ring; the matrix structure formed after the outer ring molten steel is cast and annealed is pearlite, and the addition of Cr can improve the stability of the pearlite structure; the addition of Mo can avoid temper brittleness and improve the structural strength of the outer ring; the addition of Ni can make the outer ring have a certain toughness; the content of S is ≤0.03%, which reduces the impact on the graphite morphology, and the graphite in the outer ring molten steel will become spherical after production; the outer ring provided in this embodiment is made of alloy material, with high hardness and high thermal cracking resistance. The setting of graphite points makes the outer ring have high-strength fatigue resistance, which reduces the probability of thermal fatigue cracks when in contact with hot steel, improves the rolling quality of steel sections, and reduces the maintenance cost of rollers.

[0035] 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%, and the remainder is Fe.

[0036] The chemical composition of the inner ring and the mass fraction of each component provided in this embodiment enable the cast inner ring to have high toughness through this ratio.

[0037] As a specific embodiment of the graphite steel roller ring of the present embodiment, the graphite steel roller ring includes an outer ring and an inner ring; wherein the chemical composition of the outer ring and the mass fraction of each component 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%, and the balance is 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%, and the balance is Fe.

[0038] Based on the same inventive concept, the present application also provides a method for manufacturing a graphite steel roller ring, which is used to manufacture a centrifugal bimetallic composite graphite steel roller ring as any one of the above-mentioned embodiments, and the method for manufacturing a graphite steel roller ring includes the following steps: S1: separately smelting the raw materials of the outer ring and the raw materials of the inner ring to form an outer ring molten steel and an inner ring molten steel, wherein silicon is added to the raw materials of the outer ring to form graphite points in the outer ring molten steel; S2: pouring the outer ring molten steel in a centrifuge to form a prefabricated outer layer; S3: pouring the inner ring molten steel in the prefabricated outer layer to form a prefabricated roller ring; S4: performing diffusion annealing treatment on the prefabricated roller ring; S5: performing heat treatment on the prefabricated roller ring to form a roller ring.

[0039] It should be noted that the heat treatment in S5 includes quenching and tempering the prefabricated roller ring, and the quenching temperature is higher than the tempering temperature, so that the performance of the roller ring is improved.

[0040] It should be noted that silicon can promote the graphitization of element C, transforming part of the carbon in the raw material into spherical graphite, and then turning the outer ring into graphite steel material, thereby improving the thermal cracking resistance of the outer ring.

[0041] Compared with the prior art, the graphite steel roller ring manufacturing method provided in this embodiment first pours the outer ring molten steel, and then pours the inner ring molten steel. The outer ring molten steel is provided with silicon elements, and graphite points are generated in the outer ring molten steel before casting, which improves the performance of the roller ring. The graphite points can avoid the generation of thermal fatigue cracks in the roller ring during the rolling of the steel section, and reduce the amount of repair of the roller ring; the outer ring molten steel and the inner ring molten steel are poured successively, so that the formed inner ring and the inner ring can be metallurgically bonded and do not fuse with each other, ensuring the high hardness of the outer ring and the high toughness of the inner ring; the steel roller ring is heat treated to eliminate the casting stress and increase the amount of steel overload of the roller ring. The roller ring manufactured by this method has multiple graphite points in the composition of the outer ring, and the graphite points turn the outer ring into graphite steel. The graphite points can inhibit the crack propagation caused by thermal fatigue during the rolling of the steel roller ring, increase the amount of steel overload of the steel roller ring in a single rolling, generate fewer cracks, reduce the amount of fatigue layer repair of the roller ring after rolling, and can reduce roller consumption and save processing costs.

[0042] In some embodiments, step S2 specifically includes: pouring the outer ring molten steel in batches in a centrifuge, and the thickness of the outer ring molten steel poured each time is the same. The thickness of the outer ring is greater than that of the inner ring. Pouring the outer ring molten steel in batches can gradually and steadily increase the molding thickness of the outer ring, avoiding adding all the outer ring molten steel at one time, resulting in different rotation speeds of the molten steel in the inner and outer layers, affecting the molding quality of the outer ring. Adding the same thickness of molten steel to the outer ring each time makes the rotation speeds of the outer ring molten steel in two adjacent pours the same, thereby improving the quality of the outer ring. The amount of molten steel poured in a single time is small, which makes it easy to control the pouring quality, make the crystals of the outer ring more refined, and improve the wear resistance of the outer ring.

[0043] During specific implementation, the outer ring molten steel is poured in two portions.

[0044] In some embodiments, the pouring temperature of the inner ring molten steel is higher than that of the outer ring molten steel. The higher pouring temperature of the inner ring can prevent the inner ring molten steel from fusing with the outer ring, thus ensuring the toughness of the inner ring. During centrifugal pouring, the higher pouring temperature of the inner ring molten steel allows the outer layer of the inner ring and the inner layer of the outer ring to be composited, thus improving the overall structural strength of the roller ring.

[0045] In some embodiments, step S1 specifically includes: smelting the raw materials of the outer ring and the raw materials of the inner ring respectively, so that the chemical composition and mass fraction of the outer ring molten steel are controlled within the range of 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%, balance Fe; control the chemical composition and mass fraction of the inner ring molten steel within the range of 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; add 0.8%SiCaBa inoculant to the outer ring molten steel and the inner ring molten steel respectively for inoculation treatment; add rare earth to the outer ring molten steel and the inner ring molten steel respectively for modification treatment.

[0046] In this embodiment, the raw materials are first smelted to form outer ring molten steel and inner ring molten steel respectively. The addition of inoculant can make the graphite blocks in the outer ring molten steel become spherical or worm-shaped free graphite, further improving the strength and toughness of the formed outer ring, that is, spherical graphite cast steel. The fatigue strength of spherical graphite cast steel is 50% greater than that of cast iron and steel without alloy and inoculant. At 550°C, the number of cycles of rollers made of spherical graphite cast steel, ordinary cast steel and cast iron materials when subjected to cold and hot fatigue until cracks appear is 119, 11, and 21 respectively; and at 600°C, it is 30, 9, and 7 respectively. The results show that the graphite morphology in the matrix of steel has a great influence on its performance. Spherical graphite can hinder the occurrence and expansion of thermal fatigue cracks. When the graphite in the steel is flaky, the number of cycles to reach the degree of damage does not exceed 63~121, while the number of cycles of spherical graphite cast steel is as high as 865~1883.

[0047] This embodiment provides a method for forming a graphite block, inoculated by an inoculant to convert carbon in the outer ring molten steel into spherical graphite, and then modified by rare earth to improve the quality of the outer ring molten steel and ensure the quality of the cast roller ring. Adding rare earth to modify the outer ring molten steel eliminates the network and large block carbides in the outer ring molten steel, which is conducive to silicon catalyzing carbon into free spherical graphite, improving the carbon element conversion efficiency of the outer ring molten steel. After the rare earth modifies the outer ring molten steel, the gas and impurity element content in the material is reduced, the material's cold and hot fatigue performance is improved, and the hardness of the outer peripheral surface of the cast outer ring is uniform.

[0048] In some embodiments, step S3 specifically includes: centrifuging the outer ring molten steel at a speed of 450 to 550 rpm for 20 to 30 minutes; pouring the inner ring molten steel in batches, with a time interval of 2 to 3 minutes between two adjacent pourings of the inner ring molten steel. This embodiment describes the pouring method of the inner ring molten steel, and the inner ring molten steel is poured in multiple times, so that the amount of inner ring molten steel poured each time is small, and the inner ring wall thickness formed by a single pouring is thin, which can ensure the toughness of the inner ring. There is an interval between the two adjacent pourings of the inner ring molten steel, which 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, affecting the toughness of the inner ring; it can also ensure the composite quality of the inner ring and the outer ring.

[0049] In specific implementation, the pouring of the inner ring molten steel is divided into two times, and the interval between the two pourings is 2 to 3 minutes, and the time interval between the pouring of the inner ring molten steel and the outer ring molten steel is 20 to 30 minutes, to ensure that when the inner ring molten steel is poured, the outer ring molten steel becomes the prefabricated outer layer.

[0050] In some embodiments, after step S5, the roller ring flaw detection is also performed. The roller ring flaw detection can check the quality and hardness of the roller ring, as well as whether there are defects, so as to improve the production quality.

[0051] The following is an embodiment of the roller ring: The alloy composition of the outer ring and the weight percentage of each alloy component are: 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%, and the rest are Fe and unavoidable impurities; The alloy composition of the inner ring and the weight percentage of each alloy composition 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%, and the rest are Fe and unavoidable impurities; The outer ring and inner ring are smelted separately. The outer ring is made of high-quality scrap steel and alloy as raw materials, and is smelted in a medium frequency furnace at a smelting temperature of 1580-1620°C. Before being discharged from the furnace, a slag remover is added to the furnace for slag treatment; the core is made of high-quality scrap steel and alloy as raw materials, and the smelting temperature is 1620-1660°C. When the molten steel of the outer ring and the inner ring is tapped, 0.8% SiCaBa inoculant is added to the ladle to inoculate the molten steel, which promotes the production of a certain amount of graphite in the molten steel and improves fatigue resistance; the molten steel is modified, and the modifier is rare earth, and the addition amount accounts for 0.2% of the total amount of molten steel; the grains are refined to improve wear resistance.

[0052] The outer layer and the inner layer are organically combined through process design. First, the outer ring of the roller ring is cast. The pouring temperature of the outer ring molten steel is 1430-1460℃. The speed of the centrifuge is 450-550 rpm to calculate the gravity multiple during pouring. After the outer ring molten steel is poured, it is centrifuged at a constant speed for 20-30 minutes, and the inner ring molten steel is poured. The pouring temperature is 80-100℃ higher than the outer layer. In order to ensure the toughness support of the inner ring, the amount of alloy added during smelting is small and the pouring temperature is high. In order to prevent the outer ring alloy from integrating into the inner ring and reducing the toughness of the inner ring, we adopt the method of pouring the inner layer of 30mm thick molten steel and cutting off the flow for 2-3 minutes. This can not only prevent the outer ring alloy from integrating into the inner ring, but also ensure the composite of the inner and outer layers, and maintain the high hardness of the outer ring and the high toughness of the inner layer. After the molten steel is poured, the centrifuge runs for 2-2.5 hours, stops the centrifuge, opens the cold mold, and takes out the prefabricated roller ring.

[0053] The prefabricated roller ring is put into the kiln for diffusion annealing at high temperature. The diffusion annealing temperature is 1050-1060℃, and the insulation time is 13-15 hours. After the insulation is completed, it is cooled in the furnace; The prefabricated roller ring is heat treated by quenching and tempering, with a quenching temperature of 930-960°C and a quenching and holding time of 10-18 hours; the tempering temperature is 450-500°C, and there is a certain bainite structure on the structure, which increases the hardness of the roller ring to HSD63-68 and improves the wear resistance. The tempering time is 20-25 hours to obtain a finished roller ring.

[0054] The finished roller rings are tested for performance to ensure that the finished roller rings have no defects in appearance. The hardness of the outer ring is HSD63 / 68, and the hardness difference of the use layer 160-180mm is ≤5HSD. The hardness of the inner ring is HSD45 / 50. The tensile strength of the inner layer is ensured to be 550-650MPa, and the flaw detection complies with the GB / T1503-2008 flaw detection standard.

[0055] 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 in the protection scope of the present invention.

Claims

1. A centrifugal bimetallic composite graphite steel roller ring, characterized in that: It comprises an outer ring and an inner ring, wherein a plurality of spherical graphite points are evenly dispersed in the outer ring, the inner ring is arranged on the inner wall of the outer ring, and the outer ring and the inner ring are integrally composite-casted.

2. The centrifugal bimetallic composite graphite steel roller ring according to claim 1, characterized in that: The wall thickness ratio of the outer ring and the inner ring is 2:

1.

3. The centrifugal bimetallic composite graphite steel roller ring according to claim 1, characterized in that: The chemical composition of the outer ring and the mass fraction of each component are: 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%, and the balance is Fe.

4. The centrifugal bimetallic composite graphite steel roller ring according to claim 1, characterized in that: 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%, and the balance is Fe.

5. A method for manufacturing a graphite steel roller ring, for manufacturing a centrifugal bimetallic composite graphite steel roller ring as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1: smelting the raw materials of the outer ring and the raw materials of the inner ring respectively to form outer ring molten steel and inner ring molten steel, wherein silicon is added to the raw materials of the outer ring to form graphite points in the outer ring molten steel; S2: pouring molten steel for the outer ring in the centrifuge to form a prefabricated outer layer; S3: pouring molten steel of the inner ring into the prefabricated outer layer to form a prefabricated roller ring; S4: The prefabricated roller ring is subjected to diffusion annealing treatment; S5: heat-treating the prefabricated roller ring to form a roller ring.

6. The method for manufacturing a graphite steel roller ring according to claim 5, characterized in that: Step S2 specifically includes: pouring the outer ring molten steel in batches in the centrifuge, and the thickness of the outer ring molten steel poured each time is the same.

7. The method for manufacturing a graphite steel roller ring according to claim 5, characterized in that: The pouring temperature of the inner ring molten steel is higher than the pouring temperature of the outer ring molten steel.

8. The method for manufacturing a graphite steel roller ring according to claim 5, characterized in that: Step S1 specifically includes: smelting the raw materials of the outer ring and the raw materials of the inner ring respectively, so that the chemical composition and mass fraction of the outer ring molten steel are controlled within the range of 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%, and the balance Fe; The chemical composition and mass fraction of the inner ring molten steel are controlled within the range of C: 1.3-1.5%, Si: 1.6-1.8%, Mn: 0.8-1.0%, P≤0.035%, S≤0.03%, Cr≤0.2%, and the balance is Fe; Add 0.8% SiCaBa inoculant into the outer ring molten steel and the inner ring molten steel respectively for inoculation treatment; Rare earth is added into the outer ring molten steel and the inner ring molten steel respectively for modification treatment.

9. The method for manufacturing a graphite steel roller ring according to claim 5, characterized in that: Step S3 specifically includes: The outer ring molten steel is centrifuged continuously at a speed of 450 to 550 revolutions per minute for 20 to 30 minutes; Pour the molten steel into the inner ring in batches, with the time interval between two adjacent pourings of molten steel in the inner ring being 2 to 3 minutes.

10. The method for manufacturing a graphite steel roller ring according to claim 5, characterized in that: After step S5, the roller ring flaw detection is also performed.