A steel wheel heat treatment system and method

Abstract

A steel wheel heat treatment system and method, comprising: a first heating furnace, heating the steel wheel to completely austenitize the steel wheel; a jet cooler, spraying a cooling medium on the surface of the steel wheel to rapidly cool the steel wheel to 100-400°C at a cooling rate of ≥5°C / s; a second heating furnace, heating the steel wheel to maintain the temperature of the steel wheel at 250-400°C. The above system is used to quench the steel wheel by spraying a cooling medium on the surface of the steel wheel. The cooling medium after quenching the steel wheel will not pollute or affect the newly sprayed cooling medium, making it easy to replace the cooling medium. As a result, the production cost is reduced, making the Q&P heat treatment of the steel wheel suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment, and in particular to a steel wheel heat treatment system and method. Background Art

[0002] In the context of lightweight automobiles, the third-generation advanced high-strength steel (AHSS) can replace traditional automobile steel to reduce weight by about 20%. At the same time, based on the safety of automobile structural parts, AHSS for automobiles is required to have excellent comprehensive mechanical properties, good collision energy absorption characteristics, and a strength-plasticity product of more than 20.0GPa·%. This requires that the material maintains high strength while also having good plasticity and toughness. The Q&P (Quenching and Partitioning) heat treatment process based on the austenite TRIP effect and α / γ complex phase organization theory can enable traditional ultra-high strength steel for hot forming to have a good strength-plasticity match.

[0003] At present, the Q&P heat treatment process is difficult to apply in industry. In industry, salt bath, quenching oil, temperature control mold and other methods are often used to achieve quenching and heat preservation. However, salt bath and quenching oil have high risk factors. Industrial application will produce a lot of pollution, thereby increasing the subsequent processing procedures and costs. The manufacturing cost of temperature control molds is high, and the requirements for part shape are high. The above methods are not conducive to the mass production of complex structural parts such as steel wheels. At the same time, due to the special structure of steel wheels, conventional quenching methods often produce quenching dead angles at the connection between the spokes and the rims, resulting in poor performance in this area, which has an adverse effect on the service performance of steel wheels. Or the weld quenching is uneven. Due to the large residual stress in the weld, it may cause the weld to crack and the wheel to deform. At the same time, salt bath and quenching oil are sensitive to the external environment. Long-term use will pollute the quenching medium, affecting the quenching and heat preservation effects, and it is difficult to replace the quenching medium.

[0004] Therefore, there is an urgent need for a steel wheel heat treatment system and method that can safely and environmentally friendly use the Q&P heat treatment process to treat steel wheels, reduce production costs and production difficulty, and make the Q&P heat treatment of steel wheels suitable for large-scale production. Summary of the invention

[0005] In view of this, the main purpose of the present invention is to provide a steel wheel heat treatment system, which can safely and environmentally friendly use the Q&P heat treatment process to treat the steel wheels, reduce quenching dead corners, and make the Q&P heat treatment of steel wheels suitable for large-scale production.

[0006] The steel wheel heat treatment system provided by the present invention comprises: a first heating furnace, which heats the steel wheel to make the steel wheel completely austenitized; a jet cooler, which can spray cooling medium on the surface of the steel wheel to make the steel wheel quickly cool to 100-400°C at a cooling rate of ≥5°C / s; and a second heating furnace, which heats the steel wheel to keep the temperature of the steel wheel at 250-400°C.

[0007] The above system is used to quench the steel wheel by spraying the cooling medium onto the surface of the steel wheel. The cooling medium after quenching the steel wheel will not pollute or affect the newly sprayed cooling medium, making it easy to replace the cooling medium. As a result, the production cost is reduced, making the Q&P heat treatment of the steel wheel suitable for large-scale production.

[0008] Preferably, the jet cooler of the present invention comprises: an upper quenching hood having an opening at the lower portion, an internal shape adapted to the outer circumferential surface of the steel wheel, and a plurality of first injection ports arranged on the inner surface; and a lower quenching hood having an external shape adapted to the inner circumferential surface of the steel wheel, and a plurality of second injection ports arranged on the outer surface; wherein the first injection ports and the second injection ports can spray cooling medium onto the steel wheel.

[0009] By adopting the above structure, the upper quenching cover and the lower quenching cover adapted to the steel wheel can make the layout of the first injection port and the second injection port more uniform and reasonable, so that the cooling is more uniform, the quenching dead angle is reduced, and the quenching effect is improved.

[0010] Preferably, the jet cooler further comprises a rotating table for placing the steel wheel, and the rotating table can drive the steel wheel to rotate.

[0011] By adopting the above system, during the process of quenching the steel wheel by spraying the cooling medium, the steel wheel is driven to rotate by the rotary table, which can make the cooling more uniform and improve the quenching effect.

[0012] Preferably, in the present invention, the cooling medium is dry air, N2, H2 or CO2.

[0013] The above system is used for cooling through dry air N2, H2 or CO2, etc., which has a high safety factor and does not generate a lot of pollution during the quenching process. There is no need to set up subsequent processing procedures and costs, thus reducing production costs.

[0014] Preferably, in the present invention, dry ice particles or water mist are added to the cooling medium.

[0015] By adopting the above system, dry ice particles or water mist can be added to the cooling medium, thereby improving the cooling performance of the cooling medium, so that the steel wheel can be cooled more quickly and the quenching efficiency can be improved.

[0016] In addition, the present application also provides a steel wheel heat treatment method, including: heating the steel wheel to make the steel wheel completely austenitized; uniformly spraying a cooling medium onto the surface of the steel wheel to quickly cool the steel wheel to 100-400°C at a cooling rate of ≥5°C / s; heating and insulating the steel wheel to maintain the temperature of the steel wheel at 250-400°C; finally, slowly cooling the steel wheel to room temperature.

[0017] By adopting the above method, the steel wheel is quenched by spraying the cooling medium onto the surface of the steel wheel. The cooling medium after quenching the steel wheel will not pollute or affect the newly sprayed cooling medium, and it is convenient to replace the cooling medium. Therefore, the production cost is reduced, and the Q&P heat treatment of the steel wheel is suitable for large-scale production.

[0018] Preferably, the temperature of the heat treatment on the steel wheel is 820-920° C., and the time of the heat treatment is 5-40 minutes.

[0019] Preferably, the heating and heat preservation time of the steel wheel is 1-15 minutes.

[0020] The above method provides the temperature and time for completely austenitizing the steel wheel, as well as the heat preservation time, thereby improving the production efficiency.

[0021] Preferably, in the present invention, the temperature at which the steel wheel is heated and kept warm is lower than the temperature of the steel wheel after rapid cooling.

[0022] By adopting the above method, the steel wheel can meet the one-step or two-step carbon distribution process to improve production efficiency.

[0023] Preferably, in the present invention, when the cooling medium is uniformly sprayed onto the surface of the steel wheel, the steel wheel rotates around the axis.

[0024] By adopting the above method, all parts of the steel wheel can be in contact with the sprayed cooling medium when cooling, so that the cooling zone is more uniform, thereby improving the quenching effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the distribution of the steel wheel heat treatment system of this application;

[0026] Figure 2 This is a schematic diagram of the structure of the jet cooler when it is working;

[0027] Figure 3 for Figure 2 Schematic diagram of the structure when the upper and lower quenching hoods are separated;

[0028] Figure 4 A flow chart of the method for heat treatment of steel wheels of the present application.

[0029] Description of Reference Numerals

[0030] The first heating furnace 1; the cooling device 2; the jet cooler 21; the rotating table 211; the lower quenching cover 212; the first cooling pipe 212a; the first injection port 212b; the upper quenching cover 213; the second cooling pipe 213a; the second injection port 213b; the fan room 22; and the second heating furnace 3. DETAILED DESCRIPTION

[0031] Below, in conjunction with the accompanying drawings, the specific structure and layout of the steel wheel heat treatment system of the present application are described in detail.

[0032] Figure 1 This is a schematic diagram of the distribution of the steel wheel heat treatment system of this application. Figure 1 As shown, the steel wheel heat treatment system of the present application includes three parts: a first heating furnace 1 (a roller bottom heating furnace in the figure, a walking beam heating furnace, etc. can also be used), a cooling device 2, and a second heating furnace 3 (a roller bottom heating furnace in the figure, a walking beam heating furnace, etc. can also be used). Among them, the first heating furnace 1 is used to heat the steel wheel so that the internal structure of the steel wheel is completely transformed into austenite; the cooling device 2 includes a jet cooler 21 and a fan room 22, which are used to uniformly cool the completely austenitized steel wheel by a controllable jet method, so that the cooling rate of each part of the steel wheel is greater than the critical cooling rate of martensite transformation. When the steel wheel is cooled to the Ms-Mf temperature range (initial quenching temperature), the steel wheel is transferred to the second heating furnace 3; the second heating furnace 3 keeps the steel wheel warm, so that the steel wheel is kept at the initial quenching temperature or above the initial quenching temperature for a period of time, so that carbon atoms are distributed from martensite to untransformed residual austenite. At this time, carbon diffuses from the supersaturated martensite to the residual austenite that has not undergone martensite transformation, so that the carbon content in the residual austenite is increased, which can improve the stability of the residual austenite in the steel and enable it to exist stably at room temperature. Finally, the microstructure at room temperature is a dual-phase structure of martensite and residual austenite.

[0033] Figure 2 It is a schematic diagram of the structure of the jet cooler 21 when it is working; Figure 3 for Figure 2 The schematic diagram of the structure when the upper quenching cover 213 and the lower quenching cover 212 are separated. Figure 1 , Figure 2 , Figure 3As shown, the jet cooler 21 includes a rotating table 211, and the rotating table 211 is used to place the steel wheel after being heated by the first heating furnace 1. The steel wheel is placed on the upper surface of the rotating table 211, which can drive the steel wheel to rotate with the axis of the steel wheel as the axis. The middle position of the rotating table 211 has a space for the lower quenching cover 212 to move. The lower quenching cover 212 is arranged in the middle position of the rotating table 211 and can move up and down in the vertical direction. The outer peripheral surface shape of the lower quenching cover 212 is adapted to the inner peripheral surface of the steel wheel, and a plurality of first cooling pipes 212a are evenly arranged on the lower quenching cover 212, and a plurality of first injection ports 212b facing outward are evenly arranged on the first cooling pipes 212a. An upper quenching cover 213 that can move up and down is arranged at the upper position of the rotating table 211, and the lower part of the upper quenching cover 213 is open, and the inner peripheral surface shape of the upper quenching cover 213 is adapted to the outer peripheral surface of the steel wheel. A plurality of second cooling pipes 213a are evenly arranged on the upper quenching cover 213, and a plurality of second injection ports 213b facing the axis are evenly arranged on the second cooling pipes 213a. After the steel wheel is transferred to the rotating platform 211, the lower quenching cover 212 rises and is located inside the steel wheel, and the upper quenching cover 213 descends and is located at the outer periphery of the steel wheel, clamping the inner and outer surfaces of the steel wheel.

[0034] A fan is arranged inside the fan room 22, and the fan is connected to the jet cooler 21 through a pipeline, so as to provide cooling gas for the jet cooler 21. The cooling gas may be dry air, N2, H2, CO2, etc., with dry ice particles or water mist added therein, and a suitable cooling gas medium may be selected according to actual conditions.

[0035] As described above, when the steel wheel is heated to complete austenitization in the first heating furnace 1, the steel wheel is output from the outlet of the first heating furnace 1 by a transfer device such as a roller and a walking beam, and the steel wheel is transferred to the rotating table 211. After the steel wheel is placed at a predetermined position, the lower quenching cover 212 rises to the inside of the steel wheel, and the upper quenching cover 213 descends to the outer peripheral surface of the steel wheel. The first injection port 212b and the second injection port 213b spray cooling gas to the inner and outer surfaces of the steel wheel. The rotating table 211 drives the steel wheel to rotate with the axis as the axis, so that the steel wheel is quickly cooled to the initial quenching temperature of 100-400°C at a cooling rate of ≥5°C / s. Then the rotating table 211 stops rotating, the upper quenching cover 213 rises, and the lower quenching cover 212 descends, and the quenching cooling of the steel wheel is completed. The steel wheel is transferred to the second heating furnace, the steel wheel is kept warm, and the steel wheel is kept at the partitioning temperature for a certain period of time, and a carbon partitioning treatment is performed, and the partitioning temperature is equal to or lower than the initial quenching temperature. After the carbon distribution treatment is completed, the steel wheel is output from the outlet of the second heating furnace 3 through a transfer device and air-cooled to room temperature, and the steel wheel completes the heat treatment.

[0036] Furthermore, the steel wheels output from the second heating furnace 3 can also be cooled to room temperature by water cooling or air cooling to speed up the cooling efficiency and improve the production rhythm.

[0037] The present application also provides a method for heat treatment of steel wheels. Figure 4 A flow chart of the heat treatment method for steel wheels of the present application is as follows: Figure 4 As shown, the specific process of the steel wheel heat treatment method is:

[0038] 1. Steel wheel heating process: The steel wheel is transferred to the first heating furnace 1 for heating, and the soaking section temperature is set to 820-920°C, and the soaking section heating time is about 5-40 minutes, until the steel wheel is completely austenitized;

[0039] 2. Cooling process: After austenitization is completed, the steel wheel is transferred to the jet cooler 21. Through the first injection port 212b and the second injection port 213b set on the upper quenching hood 213 and the lower quenching hood 212, a controllable jet method is adopted (controlling the injection speed of the cooling medium, thereby controlling the cooling speed) to spray the cooling medium onto the inner and outer surfaces of the steel wheel. The rotating table 211 drives the steel wheel to rotate around the axis of the steel wheel to uniformly cool all parts of the steel wheel. The cooling medium can be dry air, N2, H2, CO2, etc., with dry ice particles or water mist added, so that the steel wheel with different shape characteristics, different thicknesses, welds and other special performance requirements can be evenly and quickly cooled to the initial quenching temperature of 100-400°C at a cooling rate of ≥5°C / s;

[0040] 3. Distribution process: The steel wheel cooled to 100-400℃ is quickly transferred to the second heating furnace 31 for heating and heat preservation to carry out carbon distribution treatment. A one-step or two-step carbon distribution process can be adopted, that is, the initial quenching temperature is equal to the distribution temperature, or the initial quenching temperature is lower than the distribution temperature. The temperature of the second heating furnace 3 is 250-400℃, and the heating time is about 1-15min;

[0041] 4. Secondary cooling process: Slowly cool the distributed steel wheel to room temperature to obtain the toughened steel wheel of the present invention.

[0042] 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, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A steel wheel heat treatment system, characterized in that: include: The first heating furnace heats the steel wheel to completely austenitize the steel wheel; The jet cooler can spray cooling medium on the surface of the steel wheel, so that the steel wheel can be quickly cooled to 100-400℃ at a cooling rate of ≥5℃ / s; the jet cooler includes an upper quenching hood, a lower quenching hood and a rotating table; the rotating table is used to place the steel wheel, the rotating table can drive the steel wheel to rotate, and the middle position of the rotating table has a space for the lower quenching hood to move; the lower quenching hood is arranged in the middle position of the rotating table and can move up and down in the vertical direction; the outer peripheral surface shape of the lower quenching hood is matched with the inner peripheral surface of the steel wheel, and a plurality of first cooling pipes are evenly arranged on the lower quenching hood, and a plurality of first injection ports facing outward are evenly arranged on the first cooling pipes; the upper quenching hood is arranged at the upper position of the rotating table and can move up and down, the lower part of the upper quenching hood is open, and the inner peripheral surface shape of the upper quenching hood is matched with the outer peripheral surface of the steel wheel; a plurality of second cooling pipes are evenly arranged on the upper quenching hood, and a plurality of second injection ports facing the axis are evenly arranged on the second cooling pipes; The second heating furnace heats the steel wheel to keep the temperature of the steel wheel at 250-400°C.

2. The steel wheel heat treatment system according to claim 1, characterized in that: The cooling medium is dry air, N2, H2 or CO2.

3. The steel wheel heat treatment system according to claim 2, characterized in that: Dry ice particles or water mist are added to the cooling medium.

4. A steel wheel heat treatment method, according to the steel wheel heat treatment system according to any one of claims 1 to 3, characterized in that: include: The steel wheel is subjected to a heating treatment to completely austenitize the steel wheel; The cooling medium is uniformly sprayed onto the surface of the steel wheel, so that the steel wheel is rapidly cooled to 100-400°C at a cooling rate of ≥5°C / s; Heating and insulating the steel wheels to keep the temperature of the steel wheels at 250-400℃; Finally, the steel wheel was allowed to cool slowly to room temperature.

5. The steel wheel heat treatment method according to claim 4, characterized in that: The temperature of the heat treatment of the steel wheel is 820-920° C., and the time of the heat treatment is 5-40 minutes.

6. The steel wheel heat treatment method according to claim 4, characterized in that: The time for heating and keeping the steel wheel warm is 1-15 minutes.

7. The steel wheel heat treatment method according to claim 4, characterized in that: The temperature at which the steel wheel is heated and kept warm is not lower than the temperature of the steel wheel after rapid cooling.

8. The steel wheel heat treatment method according to claim 4, characterized in that: When the cooling medium is uniformly sprayed onto the surface of the steel wheel, the steel wheel rotates around the axis.

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