High speed steel roll ring for rail beam rolling and manufacturing method thereof

Abstract

The application discloses a high-speed steel roller ring for rail beam rolling and a manufacturing method thereof, and belongs to the technical field of roller ring preparation. The high-speed steel roller ring comprises a high-speed steel working layer and a graphite steel core part. The chemical components and mass percentage of each component of the working layer are as follows: C 1.0-2.0%, Si 0.2-1.0%, Mn 0.5-1.0%, Cr 4.0-8.0%, Ni 1.0-3.0%, Mo 4.0-6.0%, V 1.0-3.0%, W 1.0-3.0%, P≤0.03%, S≤0.03%, and the rest is Fe and inevitable impurities. The chemical components and mass percentage of each component of the core part are as follows: C 1.0-2.0%, Si 1.0-3.0%, Mn 0.5-1.0%, Ni 0.2-1.0%, Mo 0.1-0.5%, Cr≤0.2%, P≤0.03%, S≤0.03%, and the rest is Fe and inevitable impurities.

Description

Technical Field

[0001] This invention belongs to the field of roller ring preparation technology, and specifically relates to a high-speed steel roller ring for rail beam rolling and its manufacturing method. Background Technology

[0002] As a vital national infrastructure, railways, including high-speed railways and urban rail transit, are constantly increasing in speed, which places higher demands on steel rails. The requirements for dimensional accuracy and surface quality are becoming more stringent. Therefore, higher requirements are placed on the roll profile retention and wear resistance of the rolled steel rails, which conventional semi-steel materials can no longer meet.

[0003] Conventional semi-steel rolling rings are prone to problems such as steel adhesion, substandard rail beam surface quality, and low production efficiency. Conventional semi-steel materials are no longer sufficient for rail beam rolling applications, severely hindering the development of rail beam factories. Therefore, there is an urgent need to improve the rolling rings used in rail beam rolling to address these issues. Summary of the Invention

[0004] The purpose of this invention is to provide a high-speed steel roller ring for use in the universal rolling of rail beams. An oxide film is formed in the early stage of rail beam rolling, which solves the problems of steel sticking, substandard rail beam surface quality, and low production efficiency that are easily encountered when using conventional semi-steel roller rings in the rail beam rolling process.

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

[0006] A high-speed steel roll ring for rail beam rolling includes a working layer made of high-speed steel and a core made of graphite steel. The chemical composition and mass percentage of each component in the working layer are: C 1.0-2.0%, Si 0.2-1.0%, Mn 0.5-1.0%, Cr 4.0-8.0%, Ni 1.0-3.0%, Mo 4.0-6.0%, V 1.0-3.0%, W 1.0-3.0%, P≤0.03%, S≤0.03%, with the remainder being Fe and unavoidable impurities. The chemical composition and mass percentage of each component in the core are: C 1.0-2.0%, Si 1.0-3.0%, Mn 0.5-1.0%, Ni 0.2-1.0%, Mo 0.1-0.5%, Cr≤0.2%, P≤0.03%, S≤0.03%, with the remainder being Fe and unavoidable impurities.

[0007] A method for preparing high-speed steel roll rings for rail beam rolling includes the following steps:

[0008] A. According to the chemical composition requirements of each part of the working layer and core of the high-speed steel roll ring for rail beam rolling, pig iron, scrap steel, raw material, alloy, etc. are added to the medium frequency furnace in sequence to obtain qualified molten steel for the working layer and core. The molten steel of the working layer is tapped at 1520-1580℃ and the molten iron of the core is tapped at 1500-1560℃ for rapid tapping. After tapping, composite modifier and inoculant are added and stirred.

[0009] B. Centrifugal casting: Glass slag is added during the casting of the working layer; after a certain interval following the casting of the working layer, molten steel is poured into the core.

[0010] C. Heat Treatment: After demolding, the roller ring undergoes slow cooling annealing in a slow cooling box. After annealing, the roller ring is rough-machined, then placed in a furnace for preheating to 300℃. After removal from the furnace, a 3mm thick heat-insulating coating is sprayed onto the core of the roller ring. It is then placed in an induction heating furnace for rapid heating of the outer layer to the quenching temperature, which is controlled at AC. cm +(80-120℃), after quenching and taking it out of the furnace, use oil cooling, and then put it into a tempering furnace for tempering. The tempering temperature is controlled at 540-580℃.

[0011] D. Finish machining: machining the high-speed steel roller ring to the finished size.

[0012] A further improvement of the technical solution of the present invention is that: in step A1, the outer layer and the core are smelted in different medium-frequency furnaces, and the power supply time is controlled according to their respective smelting time and furnace exit time.

[0013] A further improvement of the technical solution of the present invention is that: in step A, the amount of composite modifier and inoculant added is 0.6-1.2%, the composite modifier added to the outer layer is K-RE, and the inoculant added to the core is Ba-Si.

[0014] A further improvement to the technical solution of the present invention is that: in step B, the centrifuge speed is controlled at 400-600 r / min, the amount of glass slag added is 0.5-1.0 kg / t, and the interval between the working layer and the core is controlled at 5-10 min.

[0015] A further improvement to the technical solution of the present invention is that the main components of the thermal insulation coating in step C are a water-based mixture of SiO2, Zr3O4, B2O3, and Na2O with a specific gravity of 1.4 to 1.5, and the spraying temperature is controlled at 240-260℃.

[0016] A further improvement to the technical solution of this invention is that: in step C, the roller ring induction furnace is rapidly heated at a rate of 80-120℃ / h, the quenching temperature is controlled at 1060-1100℃, the holding time is controlled at 2-4h, and after exiting the furnace, the whole thing is immersed in an oil bath, the cooling time is controlled at 20-30min, the tempering holding time is controlled at 30-50h, and the number of tempering cycles is controlled at 3-4 times.

[0017] A further improvement of the technical solution of the present invention is that the working layer of the high-speed steel roller ring prepared has a thickness of 200-220mm, an outer layer hardness of HSD80-90, and a core hardness range of HSD35-45.

[0018] A further improvement of the technical solution of the present invention is that: when the high-speed steel roll ring prepared is rolled into a rail beam, an oxide film is formed in a humid and hot steam environment under high temperature, high pressure and strong water conditions, with a thickness of 1 to 3 μm.

[0019] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0020] The high-speed steel roll ring for rail beam rolling designed in this invention uses high-speed steel for the outer layer, which mainly forms an oxide film in the early stage of rolling, changing the sliding friction of the rolling process into rolling friction. Through high-temperature quenching and multiple tempering, the hardness and wear resistance are improved, solving problems such as steel sticking, substandard surface quality, and low rolling efficiency during rail rolling. The inner layer is made of graphite steel to improve the toughness and strength of the roll ring and prevent rolling accidents such as cracking during use.

[0021] The high-speed steel roll ring prepared by this invention has high strength, good red hardness, good wear resistance, and good accident resistance. An oxide film is formed in the early stage of rolling, which transforms sliding friction into rolling friction, solving the problem of steel sticking during rolling. After being put into use, it has less wear and its online time is extended by 2-3 times compared with conventional semi-steel materials.

[0022] This invention discloses a high-speed steel roll ring for rail beam rolling and its manufacturing method. Through component ratio and heat treatment process, the outer layer achieves high red hardness and wear resistance, and forms an oxide film under special conditions of rail beam rolling. First, it plays the role of "anti-cushioning" to improve impact resistance. Second, the oxide film is in the form of granular particles, which changes sliding friction into rolling friction. Attached Figure Description

[0023] Figure 1 The metallographic structure of the outer layer of the roller ring obtained in Example 1 is 100 μm.

[0024] Figure 2 The metallographic structure of the outer layer of the roller ring obtained in Example 1 is shown in the image (20 μm).

[0025] Figure 3The metallographic structure of the outer layer of the roller ring obtained in Example 2 is shown in the image at 100 μm.

[0026] Figure 4 The metallographic structure of the outer layer of the roller ring obtained in Example 2 is shown in the image (20 μm).

[0027] Figure 5 The metallographic structure of the outer layer of the roller ring obtained in Example 3 is 100 μm.

[0028] Figure 6 The image shows the metallographic structure of the outer layer of the roller ring obtained in Example 3, with a thickness of 20 μm. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] The following table shows the composition and weight percentage of the working layer and core of a high-speed steel roller ring:

[0032]

[0033] The remainder consists of Fe and unavoidable impurities.

[0034] The manufacturing process of a high-speed steel roller ring is as follows:

[0035] A1. According to the chemical composition requirements of the inner and outer layers of the high-speed steel roller ring for rail beam rolling, pig iron, scrap steel, material head, alloy, etc. are added to two medium frequency furnaces in sequence. The outer layer of molten steel is energized first. After melting and clearing, the core molten iron is energized to obtain qualified inner and outer layers of molten steel.

[0036] A2. The outer layer of molten steel is tapped out of the furnace at a temperature of 1560℃ and then quickly tapped out. 1.0% / t of K-RE composite modifier is added to the ladle and stirred. The inner layer of molten iron is tapped out of the furnace at a temperature of 1540℃ and then quickly tapped out. 0.8% of inoculant Ba-Si is added with the flow and stirred.

[0037] B. Centrifugal casting

[0038] B1. The centrifuge speed is controlled at 560 r / min. The outer layer is poured first. When pouring the outer layer, 1.0 kg / t of glass slag is added with the flow.

[0039] B2. After the outer layer is poured, start timing. When the time reaches 8 minutes, start pouring the core steel.

[0040] C. Heat treatment

[0041] After the roller ring rotates in the centrifuge for 180 minutes, it is stopped, unmolded, and then slowly cooled and annealed in a slow cooling box. After annealing, the roller ring undergoes rough machining, and then it is placed in a furnace for preheating to 300℃. After being removed from the furnace, a heat-insulating coating with a thickness of 3mm is sprayed onto the core of the roller ring. Then, it is placed in an induction heating furnace for heating, so that the outer layer is rapidly heated to the quenching temperature at a rate of 80-120℃ / h. The quenching temperature is controlled at 1060-1100℃, and the holding time is controlled at 2h. After quenching, it is oil-cooled and then tempered in a tempering furnace at a tempering temperature controlled at 540-580℃. Finally, the whole thing is immersed in an oil bath for cooling time of 20-30 minutes and tempering holding time of 50h, with the number of tempering cycles controlled at 4.

[0042] The main components of the thermal insulation coating are a water-based mixture of SiO2, Zr3O4, B2O3, and Na2O, with a specific gravity of 1.4 to 1.5, and the spraying temperature is controlled at 240-260℃.

[0043] D. Fine turning

[0044] After the high-speed steel roller ring is tempered, it is taken out of the furnace to the processing workshop and precision machined to the finished size, with a working layer thickness of 200-220mm.

[0045] The high-speed steel roll ring prepared by this invention has high strength, good red hardness, good wear resistance, and forms an oxide film in the early stage of rolling, which acts as an "anti-impact pad". At the same time, it realizes the transformation of sliding friction into rolling friction in the rolling process, resulting in less wear after use on the machine. The single rolling capacity is increased from 2000t to 5500t, and the millimeter rolling amount is 5200t.

[0046] Example 2

[0047] The following table shows the composition and weight percentage of the working layer and core of a high-speed steel roller ring:

[0048]

[0049]

[0050] The remainder consists of Fe and unavoidable impurities.

[0051] The manufacturing process of a high-speed steel roller ring is as follows:

[0052] A1. According to the chemical composition requirements of the inner and outer layers of the high-speed steel rolling ring for rail beams, pig iron, scrap steel, material heads, alloys, etc. are added to two medium-frequency furnaces in sequence. The outer layer of molten steel is energized first. After melting and clearing, the core molten iron is energized to obtain qualified inner and outer layers of molten steel.

[0053] A2. The outer layer of molten steel is tapped out of the furnace at a temperature of 1558℃ and then quickly tapped out. 1.0% / t of K-RE composite modifier is added to the ladle and stirred. The inner layer of molten iron is tapped out of the furnace at a temperature of 1542℃ and then quickly tapped out. 0.8% of inoculant Ca-Si is added with the flow and stirred.

[0054] B. Centrifugal casting

[0055] B1. The centrifuge speed is controlled at 480 r / min. The outer layer is poured first. When pouring the outer layer, 1.0 kg / t of glass slag is added with the flow.

[0056] B2. After the outer layer is poured, start timing. When the time reaches 8 minutes, start pouring the core steel.

[0057] C. Heat treatment

[0058] After the roller ring rotates in the centrifuge for 160 minutes, it is stopped, unmolded, and then slowly cooled and annealed in a slow cooling box. After annealing, the roller ring undergoes rough machining, and then it is placed in a furnace for preheating to 300℃. After being removed from the furnace, a heat-insulating coating with a thickness of 3mm is sprayed onto the core of the roller ring. Then, it is placed in an induction heating furnace for heating, so that the outer layer is rapidly heated to the quenching temperature at a rate of 80-120℃ / h. The quenching temperature is controlled at 1060-1100℃, and the holding time is controlled at 4h. After quenching, it is oil-cooled and then tempered in a tempering furnace at a tempering temperature controlled at 540-580℃. Finally, the whole thing is immersed in an oil bath for cooling time of 20-30 minutes and tempering holding time of 30h. The number of tempering cycles is controlled at 3.

[0059] The main components of the thermal insulation coating are a water-based mixture of SiO2, Zr3O4, B2O3, and Na2O, with a specific gravity of 1.4 to 1.5, and the spraying temperature is controlled at 240-260℃.

[0060] D. Fine turning

[0061] After the high-speed steel roller ring is tempered, it is taken out of the furnace to the processing workshop and precision machined to the finished size, with a working layer thickness of 200-220mm.

[0062] The high-speed steel roll ring prepared by this invention possesses high strength, good red hardness, good wear resistance, and forms an oxide film in the early stage of rolling, acting as an "anti-impact pad." Simultaneously, it transforms sliding friction into rolling friction during the rolling process, resulting in less wear after use. The single rolling capacity increases from 2000t to 5300t, and the millimeter rolling yield reaches 5050t. The oxide film is formed by the reaction of Cr, Mo, V, and W carbides on the surface of the high-speed steel roll with oxygen in the air under humid and hot conditions, creating a dense oxide film. The oxide film is primarily light gray or light blue in color.

[0063] Example 3

[0064] The following table shows the composition and weight percentage of the working layer and core of a high-speed steel roller ring:

[0065]

[0066] The remainder consists of Fe and unavoidable impurities.

[0067] The manufacturing process of a high-speed steel roller ring is as follows:

[0068] A1. According to the chemical composition requirements of the inner and outer layers of the high-speed steel rolling ring for rail beams, pig iron, scrap steel, material heads, alloys, etc. are added to two medium-frequency furnaces in sequence. The outer layer of molten steel is energized first. After melting and clearing, the core molten iron is energized to obtain qualified inner and outer layers of molten steel.

[0069] A2. The outer layer of molten steel is tapped out of the furnace at a temperature of 1558℃ and then quickly tapped out. 1.1% / t of K-RE composite modifier is added to the ladle and stirred. The inner layer of molten iron is tapped out of the furnace at a temperature of 1542℃ and then quickly tapped out. 0.7% of inoculant Ca-Si is added with the flow and stirred.

[0070] B. Centrifugal casting

[0071] B1. The centrifuge speed is controlled at 480 r / min. The outer layer is poured first. When pouring the outer layer, 0.8 kg / t of glass slag is added with the flow.

[0072] B2. After the outer layer is poured, start timing. When the time reaches 10 minutes, start pouring the core steel.

[0073] C. Heat treatment

[0074] After the roller ring rotates in the centrifuge for 160 minutes, it is stopped, unmolded, and then slowly cooled and annealed in a slow cooling box. After annealing, the roller ring undergoes rough machining, and then it is placed in a furnace for preheating to 300℃. After being removed from the furnace, a heat-insulating coating with a thickness of 3mm is sprayed onto the core of the roller ring. Then, it is placed in an induction heating furnace for heating, so that the outer layer is rapidly heated to the quenching temperature at a rate of 80-120℃ / h. The quenching temperature is controlled at 1060-1100℃, and the holding time is controlled at 3h. After quenching, it is oil-cooled and then tempered in a tempering furnace at a tempering temperature controlled at 540-580℃. Finally, the whole thing is immersed in an oil bath for cooling time of 20-30 minutes and tempering holding time of 45h. The number of tempering cycles is controlled at 4.

[0075] The main components of the thermal insulation coating are a water-based mixture of SiO2, Zr3O4, B2O3, and Na2O, with a specific gravity of 1.4 to 1.5, and the spraying temperature is controlled at 240-260℃.

[0076] D. Fine turning

[0077] After the high-speed steel roller ring is tempered, it is taken out of the furnace to the processing workshop and precision machined to the finished size, with a working layer thickness of 200-220mm.

[0078] Figure 1-6 The images show the metallographic structures of Examples 1, 2, and 3 at different magnifications. Figure 1 , 2 The metallographic structure of Example 1 is shown, consisting of martensite + austenite + carbides 5.86%. Figure 3 , 4 The metallographic structure of Example 2 is shown, consisting of 5.26% martensite, austenite, and carbides. Figure 5 , 6 The metallographic structure of Example 3 is shown as martensite + austenite + carbides 4.01%.

[0079] Comparative Example 1

[0080] The following table shows the composition and weight percentage of the working layer and core of a high-speed steel roller ring:

[0081]

[0082] A1. According to the chemical composition requirements of the inner and outer layers of the high-speed steel roller ring for rail beam rolling, pig iron, scrap steel, material head, alloy, etc. are added to two medium frequency furnaces in sequence. The outer layer of molten steel is energized first. After melting and clearing, the core molten iron is energized to obtain qualified inner and outer layers of molten steel.

[0083] A2. The outer layer of molten steel is tapped out of the furnace at a temperature of 1558℃ and then quickly tapped out. 1.0% / t of K-RE composite modifier is added to the ladle and stirred. The inner layer of molten iron is tapped out of the furnace at a temperature of 1542℃ and then quickly tapped out. 0.8% of inoculant Ca-Si is added with the flow and stirred.

[0084] B. Centrifugal casting

[0085] B1. The centrifuge speed is controlled at 560 r / min. The outer layer is poured first. When pouring the outer layer, 1.0 kg / t of glass slag is added with the flow.

[0086] B2. After the outer layer is poured, start timing. When the time reaches 8 minutes, start pouring the core steel. The working layer (outer layer) thickness is 200-220mm.

[0087] C. Heat treatment

[0088] C1. After the roller rings rotate for 180 minutes inside the centrifuge, stop the machine, open the box, and demold.

[0089] C1. After the roller ring is demolded, it is loaded into the furnace for spheroidizing annealing. The annealing temperature is controlled at 860℃ and the holding time is 2h.

[0090] C2. After circular annealing of the rollers, rough machining is performed.

[0091] C3. After rough machining of the roller ring, it underwent high-temperature quenching and multiple tempering processes. The quenching temperature was controlled at 1080℃, held for 1 hour, and then air-cooled. The tempering temperature was controlled at 560℃, and the tempering holding time was 10 hours. The tempering was repeated three times. As a result, the product was found to be cracked and scrapped.

[0092] Multiple experiments were conducted with the same working layer and core composition, the same process steps, and the same working layer thickness as Comparative Example 1. The difference was that the annealing holding time was changed to 4h and 10h, the quenching holding time to 2h and 4h, and the tempering holding time to 30h and 50h. As a result, the products in the multiple experiments all cracked and were scrapped.

[0093] This invention compares the material properties of bimetallic high-speed steel roller rings with those of conventional semi-steel rollers.

[0094] Hardness / HSD Number of times steel is bonded Steel throughput per pass / t Millimeter rolling amount / t Standard semi-steel material 57-63 100 2000 1000 Example 1 80-90 0 5000 5000t

[0095] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for manufacturing a high speed steel roller ring for rail beam rolling, comprising a working layer of high speed steel material and a core of graphite steel material, characterized in that: The chemical composition of the working layer and the mass percentage of each component are C 1.0-2.0%, Si 0.2-1.0%, Mn 0.5-1.0%, Cr 4.0-8.0%, Ni 1.0-3.0%, Mo 4.0-6.0%, V 1.0-3.0%, W 1.0-3.0%, P≤0.03%, S≤0.03%, and the rest is Fe and inevitable impurities; the chemical composition of the core and the mass percentage of each component are C 1.0-2.0%, Si 1.0-3.0%, Mn 0.5-1.0%, Ni 0.2-1.0%, Mo 0.1-0.5%, Cr≤0.2%, P≤0.03%, S≤0.03%, and the rest is Fe and inevitable impurities; The preparation method comprises the following steps: A, according to the requirements of the chemical composition of the working layer and the core of the high-speed steel roll ring, raw iron, scrap steel, material head and alloy are sequentially added into a medium frequency furnace to obtain qualified molten steel of the working layer and the core, the working layer molten steel is discharged at a temperature of 1520-1580 ℃, and the core molten steel is quickly discharged at a temperature of 1500-1560 ℃, then a composite modifier and an inoculant are added and stirred after being discharged; B, centrifugal casting, when the working layer is cast, glass slag is added along with the flow; after the working layer is cast, the core steel is cast after a certain interval; C, heat treatment: after the roll ring demoulding, slow cooling box slow cooling annealing, roll ring annealing, rough machining, then the roll ring furnace preheating, preheating to 300℃, then out of the roll ring core spray coating, coating thickness 3mm, then loaded induction heating furnace heating, the outer layer rapidly heated to quenching temperature, quenching temperature control in AC cm + (80-120℃), quenching out of the furnace, then loaded back into the tempering furnace tempering, tempering temperature control in 540-580℃, tempering frequency control in 3-4 times; D, finish turning, the high-speed steel roll ring is processed to the finished product size; The prepared high-speed steel roll ring forms an oxide film in a wet and hot steam environment formed under high temperature, high pressure and strong water conditions during rail beam rolling, and the thickness of the oxide film is 1-3 μm.

2. The method of claim 1, wherein the high speed steel roll ring for rail beam rolling is prepared by the steps of: In step A, the outer layer and the core are smelted in different medium frequency furnaces, and different power feeding times are controlled according to the smelting time and the discharging time of each. ​ 3. The method of claim 1, wherein the high speed steel roll ring for rail beam rolling is prepared by the steps of: In step A, the adding amount of the composite modifier and the inoculant is 0.6-1.2%, the composite modifier added in the outer layer is K-RE, and the inoculant added in the core is Ba-Si. ​ 4. The method of claim 1, wherein the high speed steel roll ring for rail beam rolling is prepared by the steps of: In step B, the rotating speed of the centrifugal machine is controlled at 400-600 r / min, the adding amount of the glass slag is 0.5-1.0 kg / t, and the interval time between the working layer and the core is controlled at 5-10 min. ​ 5. The method of claim 1, wherein the high speed steel roll ring for rail beam rolling is prepared by the steps of: In step C, the main component of the heat preservation coating is a water-based mixture of SiO2, Zr3O4, B2O3 and Na2O, the specific gravity is 1.4-1.5, and the spraying temperature is controlled at 240-260 ℃. ​ 6. The method of claim 1, wherein the high speed steel roll ring for rail beam rolling is prepared by the steps of: In step C, the roll ring is loaded into an induction furnace, the temperature is quickly raised, the temperature rising speed is 80-120 ℃ / h, the quenching temperature is controlled at 1060-1100 ℃, the holding time is controlled at 2-4 h, after being discharged, the whole roll ring is immersed into an oil pool, the cooling time is controlled at 20-30 min, and the tempering holding time is controlled at 30-50 h. ​ 7. The method of claim 1, wherein the high speed steel roll ring for rail beam rolling is prepared by the steps of: The prepared high-speed steel roll ring has a working layer thickness of 200-220 mm, an outer layer hardness of HSD 80-90, and a core hardness range of HSD 35-45. ​

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