Centrifugal composite high-carbon high-speed steel roller and preparation method

Abstract

The invention discloses a centrifugal composite high-carbon high-speed steel roller and a preparation method, and belongs to the technical field of rollers, the preparation method comprises the following steps: S1, raw materials of a working layer and a core part are respectively put into an electric furnace for smelting, and working layer molten steel and core part molten steel are respectively obtained; s2, molten steel of the working layer is poured into a cold mold cavity of a horizontal centrifugal machine, and meanwhile casting powder is added in the pouring process; s3, a cold type cavity of the horizontal centrifugal machine is sealed through a plug and a centrifugal machine cover, and convection between a casting mold in the cold type cavity and outside air is reduced; s4, when the temperature of the inner cavity of the working layer reaches 1030-1037 DEG C, the speed of the centrifugal machine is reduced until the centrifugal machine stops rotating, and then casting powder is poured out; and S5, after the working layer molten steel is solidified, the core molten iron is spheroidized, and then the spheroidized core molten iron is poured into an inner cavity of the working layer. The wear resistance of the working layer of the roller and the flaw detection quality and strength of the bonding layer are guaranteed, the stripping risk of the working layer is reduced, and the yield is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of rolling rollers, in particular to the technical field of rolling roller manufacturing, and specifically to a centrifugal composite high-carbon high-speed steel rolling roller and a preparation method thereof. Background Art

[0002] Rollers are the main working parts and tools on the rolling mill that cause continuous plastic deformation of metal. Rollers are mainly composed of three parts: roll body, roll neck and shaft head. The roll body is the middle part of the roll that actually participates in rolling metal. It has a smooth cylindrical or grooved surface. The roll neck is installed in the bearing and transmits the rolling force to the frame through the bearing seat and the pressing device. The drive end shaft head is connected to the gear seat through the connecting shaft to transmit the rotational torque of the motor to the roll. The rolls can be arranged in the form of two rolls, three rolls, four rolls or multiple rolls in the rolling mill frame.

[0003] High-speed steel rolls contain a large amount of alloy elements such as V, W, Cr, Mo, Nb, etc., and have a high room temperature hardness of HS82-90. At the same time, they have good high-temperature red hardness characteristics. They can still guarantee HS78 or above at above 500°C. Therefore, they have excellent high-temperature wear resistance and are currently widely used in steel rolling production. Replacing semi-steel rolls, high-chromium cast iron rolls, high-nickel-chromium-molybdenum infinitely chilled rolls and needle-shaped bainite ductile iron rolls with high-speed steel rolls has achieved good results in production practice in terms of increasing rolling volume and extending roll replacement cycles.

[0004] The centrifugal composite high-carbon high-speed steel roll involved in the present invention refers to the working roll of the rear section of hot rolling finishing rolling. The working layer material of this type of roll contains a large amount of alloy elements such as Cr, Ni, Mo, V, Nb, etc., the core material is ductile iron with good toughness, the working layer alloy content is relatively high, the bonding layer structure of the roll working layer and the core is difficult to control, the bonding layer strength and the bonding layer flaw detection quality are difficult to ensure, and there are problems of working layer peeling and low yield rate.

[0005] Therefore, the general centrifugal composite high-carbon high-speed steel roll casting process has the following disadvantages: the wear resistance of the working layer is not ideal, the flaw detection quality of the bonding layer is poor, and the strength of the bonding layer is low. Summary of the invention

[0006] In order to solve the problems of unsatisfactory wear resistance of the working layer, poor flaw detection quality of the bonding layer and low strength of the bonding layer in the prior art centrifugal composite high-carbon high-speed steel roller casting process, the present invention provides a centrifugal composite high-carbon high-speed steel roller and a preparation method, which ensure the wear resistance of the roller working layer, the flaw detection quality and strength of the bonding layer, reduce the risk of working layer peeling and improve the yield rate.

[0007] The technical scheme adopted by the centrifugal composite high-carbon high-speed steel roller and the preparation method of the present invention is:

[0008] A centrifugal composite high-carbon high-speed steel roller, comprising a working layer and a core, wherein the weight percentages of different alloys in the chemical composition of the working layer are: C: 1.5-3.5%, Si: 2.2-4.2%, Mn: 0.2-1.2%, Cr: 2.0-3.0%, Ni: 4.0-5.0%, Mo: 3.5-4.5%, V: 3.0-4.0%, Nb: 0.2-1.2%, and the balance is Fe and unavoidable impurities;

[0009] The weight percentages of different alloys in the chemical composition of the core are: C: 3.0-4.0%, Si: 1.5-2.5%, Mn < 0.8%, P < 0.1%, S < 0.02%, Mg: 0.03-0.04%, Re: 0.01-0.03%, V < 0.1%, Cr < 0.4%, Ni < 0.5%, Mo < 0.3%, W < 0.1%, and the remainder is Fe and unavoidable impurities.

[0010] A further improvement of the above technical solution of the present invention is that the material of the working layer is high-carbon high-speed steel, and the material of the core is ductile iron.

[0011] A method for preparing a centrifugal composite high-carbon high-speed steel roll, used for preparing the centrifugal composite high-carbon high-speed steel roll, comprises the following steps:

[0012] S1. Put the raw materials of the working layer and the core into an electric furnace for smelting to obtain molten steel for the working layer and molten iron for the core respectively;

[0013] S2, pouring the working layer molten steel into the cold mold cavity of the horizontal centrifuge, and adding protective slag during the pouring process;

[0014] S3. Use a plug and a centrifuge cover to seal the cold mold cavity of the horizontal centrifuge to reduce convection between the mold in the cold mold cavity and the outside air;

[0015] S4. When the temperature of the inner cavity of the working layer reaches 1030-1037°C, the centrifuge is decelerated until it stops, and then the protective slag is poured out;

[0016] S5. After the molten steel of the working layer solidifies, the core molten iron is spheroidized, and then the spheroidized core molten iron is poured into the inner cavity of the working layer.

[0017] A further improvement of the above technical solution of the present invention is that the working layer is smelted at a temperature of 1500°C, and the core is smelted at a temperature of 1480°C.

[0018] A further improvement of the above technical solution of the present invention is that the pouring temperature of molten steel in the working layer in step S2 is 1250-1350°C.

[0019] A further improvement of the above technical solution of the present invention is that the rotation speed of the centrifugal casting of the roller working layer in step S2 is 600-700 rpm.

[0020] A further improvement of the above technical solution of the present invention is that: in the step S4, a thermocouple is inserted into the center of the mold during the solidification process of the working layer to measure the inner cavity temperature of the working layer in real time.

[0021] A further improvement of the above technical solution of the present invention is that the pouring temperature of the molten iron in the core of the rolling mill roll in step S5 is 1300-1400°C.

[0022] A further improvement of the above technical solution of the present invention is that: in step S5, a finite element numerical simulation method is used to calculate the solidification time of the working layer.

[0023] A further improvement of the above technical solution of the present invention is that the finite element numerical simulation method specifically includes determining the simulation boundary conditions according to the actual temperature measurement data, taking the temperature field of the rolling roller working layer and the tooling before pouring the core as the initial condition, importing the core solidification quality simulation model for calculation and analysis, determining the optimal core pouring time parameters, and controlling the deviation by ±0.5 minutes.

[0024] Due to the adoption of the above technical solution, the technical advances achieved by the present invention include:

[0025] The working layer material of the centrifugal composite high-carbon high-speed steel roller of the present invention is high-carbon high-speed steel, and the core is spheroidal cast iron, which ensures good wear resistance of the working layer, and the bonding layer has no casting defects in flaw detection, and the anti-etching thickness is less than 20mm. The carbide content of the working layer of the roller is stably controlled between 15-25%, and the performance is good during use.

[0026] The present invention adds chromium, nickel, molybdenum, vanadium and niobium to the working layer of the roll, a part of which obtains high-hardness wear-resistant carbide, and a part of which is integrated into the matrix of the working layer of the roll, thereby improving the hardenability and red hardness of the working layer of the roll; the core of the roll is made of ductile iron to ensure that the core of the roll has good strength and toughness as a whole. At the same time, the working layer of the roll contains Cr: 2.0-3.0%, Ni: 4.0-5.0%, Mo: 3.5-4.5%, V: 3.0-4.0%, and Nb: 0.2-1.2%, and the four are reasonably proportioned, which refines the grains and improves the mechanical properties.

[0027] At the same time, the present invention selects a horizontal centrifugal casting roller working layer, which enables the liquid metal to fill the cold mold cavity well in the radial direction and form a free surface of the casting, which is helpful to control the thickness difference of the working layer and remove the gas and inclusions in the liquid metal, thereby improving the organization and mechanical properties of the working layer; and by controlling the rotation speed to reduce the adverse effects of alloy element segregation, the organizational uniformity of the working layer can be improved.

[0028] The present invention adopts the finite element numerical simulation method to design the pouring time of the core, which is beneficial to the coordination of the outer layer temperature and the core temperature, so that the molten iron solidifies sequentially, prevents the generation of loose bonding layer casting defects and excessive corrosion of the outer layer by the core, and improves the flaw detection quality and mechanical properties of the bonding layer. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific implementation methods. In the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0030] Embodiment 1

[0031] In this embodiment, as shown in Table 1, the working layer material of the centrifugal composite high-carbon high-speed steel roller is high-carbon high-niobium high-speed steel, and the weight percentages of different alloys in the composition are: C: 3.21%, Si: 2.15%, Mn: 0.87%, Cr: 2.14%, Ni: 4.35%, Mo: 3.53%, V: 3.2%, Nb: 1.01%, and the remainder is Fe and unavoidable impurities.

[0032] The core material is ductile iron, and the weight percentages of different alloys in the composition are: C: 3.31%, Si: 2.22%, Mn: 0.36%, P: 0.03%, S: 0.019%, Mg: 0.031%, Re: 0.011%, V: 0.03%, Cr: 0.3%, Ni: 0.41%, Mo: 0.1%, W: 0.1%, and the balance is Fe and inevitable impurities.

[0033] The preparation of the above-mentioned roller comprises the following steps:

[0034] S1. Put the raw materials of the working layer and the core into an electric furnace for smelting respectively. The smelting temperature of the working layer is 1500°C and the smelting temperature of the core is 1480°C.

[0035] S2. Pour the molten iron of the working layer of the roller into the horizontal centrifuge casting mold at a pouring temperature of 1300°C and a rotation speed of 651 rpm for centrifugal pouring of the working layer. Add protective slag during the pouring process.

[0036] S3. After pouring the roller working layer, use plugs and centrifuge covers to reduce air convection between the mold and the outside world.

[0037] S4. When the inner cavity temperature of the working layer of the roller reaches 1031°C, the centrifuge is decelerated to stop and the protective slag in the mold is poured out; at the same time, during the solidification process of the working layer, a thermocouple is used, inserted into the center of the mold, and the inner cavity temperature of the working layer is measured in real time.

[0038] S5. Spheroidize the core of the roll before pouring: After the molten iron of the roll working layer solidifies, pour the molten iron of the roll core, and the pouring temperature of the roll core is 1342° C. Specifically, the solidification time of the roll working layer is calculated by the finite element numerical simulation method, which is used as the pouring time of the roll core, which is 22 minutes, and the control deviation is ±0.5 minutes.

[0039] Table 1

[0040]

[0041] Embodiment 2

[0042] In this embodiment, as shown in Table 2, the working layer material of the centrifugal composite high-carbon high-speed steel roller is high-carbon high-niobium high-speed steel, and the weight percentages of different alloys in the composition are: C: 3.25%, Si: 2.18%, Mn: 0.89%, Cr: 2.18%, Ni: 4.38%, Mo: 3.56%, V: 3.25%, Nb: 1.05%, and the remainder is Fe and unavoidable impurities.

[0043] The core material is ductile iron, and the weight percentages of different alloys in the composition are: C: 3.34%, Si: 2.24%, Mn: 0.38%, P: 0.05%, S: 0.021%, Mg: 0.034%, Re: 0.012%, V: 0.04%, Cr: 0.31%, Ni: 0.42%, Mo: 0.11%, W: 0.11%, and the balance is Fe and inevitable impurities.

[0044] The preparation of the above-mentioned roller comprises the following steps:

[0045] S1. Put the raw materials of the working layer and the core into an electric furnace for smelting respectively. The smelting temperature of the working layer is 1505°C and the smelting temperature of the core is 1484°C.

[0046] S2. Pour the molten iron of the working layer of the roller into the horizontal centrifuge casting mold. The pouring temperature is 1308°C, and the speed of centrifugal pouring of the working layer is 658rpm. Protective slag is added during the pouring process.

[0047] S3. After pouring the roller working layer, use plugs and centrifuge covers to reduce air convection between the mold and the outside world.

[0048] S4. When the inner cavity temperature of the working layer of the roller reaches 1033℃, the centrifuge is slowed down to stop and the protective slag in the mold is poured out; at the same time, during the solidification process of the working layer, a thermocouple is used, inserted into the center of the mold, and the inner cavity temperature of the working layer is measured in real time.

[0049] S5. Spheroidize the core of the roll before pouring: After the molten iron of the roll working layer solidifies, pour the molten iron of the roll core, and the pouring temperature of the roll core is 1348° C. Specifically, the solidification time of the roll working layer is calculated by the finite element numerical simulation method, which is used as the pouring time of the roll core, which is 22.5 minutes, and the control deviation is ±0.5 minutes.

[0050] Table 2

[0051]

[0052] Comparative Example 1

[0053] In this embodiment, the working layer material of the centrifugal composite high-carbon high-speed steel roller is high-carbon high-niobium high-speed steel, and the weight percentages of different alloys in the composition are: C: 3.32%, Si: 2.25%, Mn: 0.85%, Cr: 1.7%, Ni: 3.9%, Mo: 1.1%, V: 2.3%, Nb: 0.2%, and the remainder is Fe and unavoidable impurities.

[0054] The core material is ductile iron, and the weight percentages of different alloys in the composition are: C: 3.2%, Si: 2.51%, Mn: 0.41%, P: 0.05%, S: 0.018%, Mg: 0.041%, Re: 0.013%, V: 0.02%, Cr: 0.2%, Ni: 0.6%, Mo: 0.08%, W: 0.05%, and the balance is Fe and inevitable impurities.

[0055] The preparation of the above-mentioned roller comprises the following steps:

[0056] S1. Put the raw materials of the working layer and the core into an electric furnace for smelting respectively. The smelting temperature of the working layer is 1495°C and the smelting temperature of the core is 1480°C.

[0057] S2. Pour the molten iron of the working layer of the roller into the horizontal centrifuge casting mold. The pouring temperature is 1372°C, and the speed of centrifugal pouring of the working layer is 687rpm. Protective slag is added during the pouring process.

[0058] S3. After pouring the roller working layer, use plugs and centrifuge covers to reduce air convection between the mold and the outside world.

[0059] S4. When the inner cavity temperature of the roller working layer reaches 1123℃, the centrifuge is decelerated to stop and the protective slag in the mold is poured out.

[0060] S5. Spheroidize the core of the roll before pouring: After the molten iron of the roll working layer solidifies, pour the molten iron of the roll core, and the pouring temperature of the roll core is 1372° C. Specifically, the solidification time of the roll working layer is calculated by the finite element numerical simulation method, which is used as the pouring time of the roll core, which is 15 minutes, and the control deviation is ±0.5 minutes.

[0061] Combining the above-mentioned Example 1, Example 2 and Comparative Example 1, it can be seen that the bonding layer between the working layer and the core of the present invention has no casting defects during flaw detection, and the present invention can reduce the number of scraps generated during the production process of the rolling mill, and at the same time, the present invention can significantly improve the hardness of the rolling mill.

[0062] In the above embodiment, the present invention provides a centrifugal composite high-carbon high-speed steel roller and a preparation method. The present invention adds chromium, nickel, molybdenum, vanadium and niobium to the roller working layer, a part of which obtains high-hardness wear-resistant carbide, and a part of which is integrated into the roller working layer matrix, thereby improving the hardenability and red hardness of the roller working layer; the roller core is made of ductile iron to ensure that the roller core has good strength and toughness as a whole. At the same time, the roller working layer contains Cr: 2.0-3.0%, Ni: 4.0-5.0%, Mo: 3.5-4.5%, V: 3.0-4.0%, and Nb: 0.2-1.2%, and the four are reasonably proportioned, which refines the grains and improves the mechanical properties.

[0063] The above-described embodiments are merely descriptions of preferred implementations of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should fall within the protection scope of the present invention, and the technical contents for which protection is sought in the present invention have been fully recorded in the claims.

Claims

1. A centrifugal composite high-carbon high-speed steel roll, comprising a working layer and a core, characterized in that: The weight percentages of different alloys in the chemical composition of the working layer are: C: 1.5-3.5%, Si: 2.2-4.2%, Mn: 0.2-1.2%, Cr: 2.0-3.0%, Ni: 4.0-5.0%, Mo: 3.5-4.5%, V: 3.0-4.0%, Nb: 0.2-1.2%, and the balance is Fe and unavoidable impurities; The weight percentages of different alloys in the chemical composition of the core are: C: 3.0-4.0%, Si: 1.5-2.5%, Mn < 0.8%, P < 0.1%, S < 0.02%, Mg: 0.03-0.04%, Re: 0.01-0.03%, V < 0.1%, Cr < 0.4%, Ni < 0.5%, Mo < 0.3%, W < 0.1%, and the remainder is Fe and unavoidable impurities.

2. The centrifugal composite high-carbon high-speed steel roller according to claim 1, characterized in that: The material of the working layer is high-carbon high-speed steel, and the material of the core is ductile iron.

3. A method for preparing a centrifugal composite high-carbon high-speed steel roll, characterized in that: The method for preparing the centrifugal composite high-carbon high-speed steel roll according to claim 1 comprises the following steps: S1. Put the raw materials of the working layer and the core into an electric furnace for smelting to obtain molten steel for the working layer and molten iron for the core respectively; S2, pouring the working layer molten steel into the cold mold cavity of the horizontal centrifuge, and adding protective slag during the pouring process; S3. Use a plug and a centrifuge cover to seal the cold mold cavity of the horizontal centrifuge to reduce convection between the mold in the cold mold cavity and the outside air; S4. When the temperature of the inner cavity of the working layer reaches 1030-1037°C, the centrifuge is decelerated until it stops, and then the protective slag is poured out; S5. After the molten steel of the working layer solidifies, the core molten iron is spheroidized, and then the spheroidized core molten iron is poured into the inner cavity of the working layer.

4. The method for preparing a centrifugal composite high-carbon high-speed steel roll according to claim 3, characterized in that: The working layer is smelted at a temperature of 1500°C, and the core is smelted at a temperature of 1480°C.

5. The method for preparing a centrifugal composite high-carbon high-speed steel roll according to claim 3, characterized in that: In step S2, the pouring temperature of molten steel in the working layer is 1250-1350°C.

6. The method for preparing a centrifugal composite high-carbon high-speed steel roll according to claim 3, characterized in that: The rotation speed of the centrifugal casting of the roller working layer in step S2 is 600-700 rpm.

7. The method for preparing a centrifugal composite high-carbon high-speed steel roll according to claim 3, characterized in that: In the step S4, during the solidification process of the working layer, a thermocouple is inserted into the center of the mold to measure the inner cavity temperature of the working layer in real time.

8. The method for preparing a centrifugal composite high-carbon high-speed steel roll according to claim 3, characterized in that: In step S5, the molten iron pouring temperature of the core of the roller is 1300-1400°C.

9. The method for preparing a centrifugal composite high-carbon high-speed steel roll according to claim 3, characterized in that: In step S5, a finite element numerical simulation method is used to calculate the solidification time of the working layer.

10. The method for preparing a centrifugal composite high-carbon high-speed steel roll according to claim 9, characterized in that: The finite element numerical simulation method specifically includes determining the simulation boundary conditions according to the actual temperature measurement data, taking the temperature field of the roller working layer and the tooling before pouring the core as the initial condition, importing the core solidification quality simulation model for calculation and analysis, determining the optimal core pouring time parameters, and controlling the deviation by ±0.5 minutes.

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