Heat treatment quenching process for high-toughness steel strip

Abstract

The invention discloses a heat treatment quenching technology for a high-toughness steel strip. The heat treatment quenching technology comprises the following steps that S1, the steel strip is pretreated; s2, heating the steel strip; s3, cooling the steel strip; s4, cleaning the steel belt; s5, tempering the steel belt; s6, heat preservation of the steel belt; in the step S1, firstly, the steel belt is cleaned, the inner side of the steel belt is soaked in clear water for scrubbing and impurity residues are removed, in the step S2, a continuous protective atmosphere furnace is used, the temperature is set to be 800-950 DEG C, the steel belt is heated, multi-zone heating can be adopted for thick or wide steel belts, it is ensured that the core reaches the temperature, and the steel belt is subjected to heat preservation and heat preservation. The heat absorption type atmosphere is used, a complete process chain including pretreatment, heating, cooling, cleaning, tempering, heat preservation and aftertreatment is arranged, all the steps are closely connected and have a synergistic effect, the internal structure performance of the steel strip is systematically improved, the overall toughness of the steel strip is effectively improved, the service life of the steel strip is effectively prolonged, and the problem that the toughness of a traditional process is insufficient is solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of quenching processes, in particular to a high-toughness steel strip heat treatment quenching process. BACKGROUND

[0002] The high-toughness steel strip is a kind of special steel strip which can significantly improve the impact toughness and fatigue resistance while maintaining high strength and hardness, and is widely used in fields with high requirements for impact resistance, fracture resistance and fatigue resistance.

[0003] The application with the publication number CN110669918A provides a high-toughness steel strip heat treatment quenching process, which comprises preheating treatment, quenching preparation heat treatment, quenching treatment, tempering treatment, polishing treatment, surface galvanizing and cutting into a warehouse. The high-toughness steel strip heat treatment quenching process provided by the application performs preliminary heating, normalizing and high-temperature tempering treatment before quenching. The preliminary heating is used to buffer the sudden high temperature of the steel strip, the normalizing treatment refines the grain of the steel strip and homogenizes the distribution of carbides, and is used to improve the toughness of the steel strip and reduce the hardness of the steel strip. In addition, the surface of the steel strip is protected during the normalizing treatment in a vacuum cover furnace, the surface quality of the steel strip is improved, the pickling process is reduced, and the cost is reduced. The high-temperature tempering is used to eliminate the stress generated during the normalizing cooling and further increase the toughness of the steel strip. The surface of the steel strip is galvanized to increase the corrosion resistance and service life of the steel strip.

[0004] The application with the publication number CN118086631A relates to a high-toughness steel strip heat treatment quenching process, which comprises the following steps: preheating treatment, quenching preparation heat treatment, quenching treatment, tempering treatment, polishing treatment, surface galvanizing and cutting into a warehouse. After the steel strip is cut according to the specifications, it is coiled and stored in the warehouse. The quenching device comprises a support, the support is fixedly connected with an oven, two partition plates are fixedly connected to the inner wall of the oven, a heating mechanism is arranged in the heating cavity, through holes are formed in the end faces of the two ends of the heating cavity, installation rollers are rotatably connected between the inner walls on the two sides of the through holes, and a cooling mechanism is arranged at the discharging end of the heating cavity. The steel strip is preheated by the heating mechanism, the preheated steel strip enters the middle heating cavity, is preheated by the heating mechanism, and the twice-preheated steel strip enters the lowermost heating cavity for the last heating. After the heating is completed, the steel strip enters the cooling mechanism for quenching. Through the twice preheating, the processing efficiency of the steel strip is improved.

[0005] Moreover, the existing steel strip is generally processed by quenching and tempering, and the steel strip processed by the quenching process in the prior art has low flexibility, corrosion resistance and service life. Therefore, the application provides a high-toughness steel strip heat treatment quenching process to solve the above problems. SUMMARY

[0006] In view of the technical problems of low flexibility, poor corrosion resistance and short service life of the steel strip made by the quenching process based on the background art, the application provides a high-toughness steel strip heat treatment quenching process.

[0007] The high-toughness steel strip heat treatment quenching process provided by the application comprises the following steps: S1: steel strip pretreatment; S2: steel strip heating; S3: steel strip cooling; S4: steel strip cleaning; S5: steel strip tempering; S6: steel strip heat preservation; S7: steel strip post-treatment.

[0008] Preferably, in the S1 step, the steel strip is first cleaned, immersed in clean water on the inner side for brushing, and impurity residues are removed; the steel strip is immersed in clean water for brushing in the pretreatment step, and oil stains, oxides and other impurity residues in the surface and gaps are thoroughly removed to create clean surface conditions for subsequent heat treatment, prevent impurities from affecting the microstructure transformation of the steel strip or causing defects at high temperatures, and improve the stability of the toughness of the final product.

[0009] Preferably, in the S2 step, a continuous protective atmosphere furnace is used, the temperature is set to 800-950 DEG C, the steel strip is heated, for thick or wide steel strips, multi-zone heating can be used to ensure that the core reaches the temperature, and endothermic atmosphere is used to prevent decarburization and oxidation of the surface of the steel strip; each centimeter of the steel strip needs to be heated for 10-15 minutes; the continuous protective atmosphere furnace is used for heating and precise temperature control to ensure that the steel strip is uniformly heated to the required temperature; for thick and wide steel strips, a multi-zone heating strategy is implemented to ensure that the core temperature fully meets the standards; and endothermic atmosphere is used to strictly protect the surface of the steel strip, effectively preventing decarburization and oxidation, and laying a foundation for obtaining uniform and refined internal microstructure and good toughness.

[0010] Preferably, in the S3 step, the steel strip is cooled using rapid quenching oil, immersed in the rapid quenching oil, and the temperature of the rapid quenching oil is strictly controlled to be 40-80 DEG C; the rapid quenching oil is used for cooling and the oil temperature is strictly controlled to ensure that the steel strip obtains a suitable cooling speed during quenching, promotes the full transformation of austenite to high-strength martensite, and reduces the risk of excessive internal stress or poor microstructure caused by too fast or too slow cooling, thereby optimizing the quenching effect to support subsequent toughness improvement.

[0011] Preferably, in the S4 step, the quenched oil or polymer residues on the surface of the steel strip are thoroughly cleaned immediately after quenching to prepare for tempering, preventing oil fume or pollution during tempering, and the surface of the steel strip is thoroughly cleaned immediately after quenching to completely remove the quenched oil or polymer residues, avoiding the generation of oil fume pollution of the environment or the adhesion of the residues to the surface of the steel strip during subsequent high-temperature tempering, which affects the uniformity of tempering, and ensuring that the tempering process proceeds smoothly under clean conditions.

[0012] Preferably, in the S5 step, the steel strip is tempered again using a continuous tempering furnace, and medium-high temperature tempering is adopted, with a temperature range of 400-550 DEG C, to ensure that the core is fully tempered, and the tempering time is 1-2 hours, and the steel strip is air-cooled after tempering, and the quenched steel strip is subjected to medium-high temperature tempering in the continuous tempering furnace, which can effectively adjust the microstructure of the quenched martensite, significantly reduce its brittleness and improve its toughness, and at the same time ensure sufficient time for the steel strip core to complete the tempering transformation, and the air cooling after tempering further stabilizes the microstructure, and finally significantly improves the overall toughness of the steel strip.

[0013] Preferably, in the S6 step, the steel strip is tempered when it cools to 100-150 DEG C, and the tempering time is 1-2.5 hours, and the tempering process helps to further stabilize the microstructure and refine the grains, thereby effectively improving the toughness and dimensional stability of the steel strip.

[0014] Preferably, in the S7 step, after tempering, the steel strip is finally straightened using a roller straightening machine, and the surface of the steel strip is then shot blasted, and the steel strip is precisely straightened using a roller straightening machine after tempering to eliminate the bending deformation generated during heat treatment, and then the surface of the steel strip is shot blasted to introduce a beneficial compressive stress layer and slightly harden the surface, which not only improves the flatness of the steel strip, but also effectively improves the fatigue resistance and overall toughness of the steel strip.

[0015] The beneficial effects of the present application are: 1. The continuous protective atmosphere furnace is used for heating and precise temperature control, ensuring that the steel strip is uniformly heated to the required temperature, and a multi-zone heating strategy is adopted for thick and wide steel strips to ensure that the core temperature fully meets the standards, and the endothermic atmosphere is used to strictly protect the surface of the steel strip, effectively preventing decarburization and oxidation, laying a foundation for obtaining uniform and refined internal microstructure and good toughness; 2. The oil temperature is strictly controlled during cooling using rapid quenching oil to ensure that the steel strip obtains an appropriate cooling speed during quenching, promotes the full transformation of austenite to high-strength martensite, and reduces the risk of excessive internal stress or poor microstructure caused by too fast or too slow cooling, optimizing the quenching effect to support subsequent toughness improvement; 3. The steel strip is cooled to a specific temperature range and heat treated, so that the internal structure of the steel strip is fully transformed at this temperature and part of the stress is released. The heat treatment process helps to further stabilize the structure and refine the grains, thereby effectively improving the toughness and dimensional stability of the steel strip; 4. After the heat preservation is completed, the steel strip is first precisely straightened using a roller straightening machine to eliminate the bending deformation generated during the heat treatment process, and then the surface of the steel strip is subjected to shot blasting treatment to introduce a beneficial compressive stress layer and slightly harden the surface. This not only improves the flatness of the steel strip, but also effectively improves its fatigue resistance and overall toughness; The present application sets up a complete process chain including pretreatment, heating, cooling, cleaning, tempering, heat preservation and post-treatment. Each step closely connects and cooperates to systematically improve the internal organizational performance of the steel strip, effectively enhance the overall toughness and service life of the steel strip, and solve the problem of insufficient toughness in traditional processes. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The workflow diagram proposed by the present application. DETAILED DESCRIPTION

[0017] The present application will be further described below in conjunction with specific embodiments.

[0018] Reference Figure 1 Example One A high-toughness steel strip heat treatment quenching process is proposed in this embodiment, including the following steps: S1: Steel strip pretreatment. First, the steel strip is cleaned by immersing it in clean water and brushing it on the inside to remove impurities and residues. The steel strip is immersed in clean water and brushed during the pretreatment step to thoroughly remove oil stains, oxides and other impurities and residues on the surface and gaps, creating clean surface conditions for subsequent heat treatment, preventing impurities from affecting the steel strip organizational transformation or causing defects at high temperatures, and improving the stability of the final product toughness; S2: Steel strip heating. A continuous protective atmosphere furnace is used, with the temperature set at 820℃. For thick or wide steel strips, multi-zone heating can be used to ensure that the core reaches the temperature. Heat-absorbing atmosphere is used to prevent decarburization and oxidation of the steel strip surface. Each centimeter of steel strip requires 13 minutes of heating. The continuous protective atmosphere furnace is used for heating and precise temperature control to ensure uniform heating of the steel strip to the required temperature. For thick and wide steel strips, a multi-zone heating strategy is implemented to ensure that the core temperature fully meets the standards. At the same time, the heat-absorbing atmosphere is used to strictly protect the surface of the steel strip, effectively preventing decarburization and oxidation, laying a foundation for obtaining uniform and refined internal structure and good toughness; S3: Steel belt cooling, using a rapid quenching oil to cool the steel belt, immersing the steel belt in the rapid quenching oil, strictly controlling the temperature of the rapid quenching oil, controlling the temperature at 50°C, using the rapid quenching oil for cooling and strictly controlling the oil temperature, ensuring that the steel belt obtains a suitable cooling speed during quenching, promoting the full transformation of austenite to high-strength martensite, while reducing the risk of excessive internal stress or poor organization caused by too fast or too slow cooling, optimizing the quenching effect to support the subsequent toughness improvement; S4: Steel belt cleaning, immediately after quenching, thoroughly cleaning the quenching oil or polymer residues on the surface of the steel belt, preparing for tempering, preventing oil smoke or pollution during tempering, immediately after quenching, thoroughly cleaning the surface of the steel belt, completely removing the quenching oil or polymer residues, avoiding the generation of oil smoke pollution environment or the adhesion of these residues on the surface of the steel belt affecting the uniformity of tempering during the subsequent high-temperature tempering process, ensuring that the tempering process is carried out smoothly under clean conditions; S5: Steel belt tempering, using a continuous tempering furnace to temper the steel belt again, adopting medium-high temperature tempering, the temperature range is usually 480, ensuring that the core is fully tempered, the time is 1.25 hours, and after tempering, air cooling is carried out, the quenched steel belt is subjected to medium-high temperature tempering in the continuous tempering furnace, this temperature range can effectively adjust the organization structure of quenched martensite, significantly reduce its brittleness and improve its toughness, while ensuring sufficient time for the steel belt core to fully complete the tempering transformation, and air cooling after tempering further stabilizes the organization, finally significantly improves the overall toughness of the steel belt; S6: Steel belt heat preservation, when the steel belt cools to 120°C, heat preservation is carried out, the heat preservation time is 1 hour, heat preservation is carried out when the steel belt cools to a certain temperature range, so that the internal organization of the steel belt fully completes the transformation and releases part of the stress at this temperature, this heat preservation process helps to further stabilize the organization structure and refine the grains, thereby effectively improving the toughness and dimensional stability of the steel belt; S7: Steel belt post-processing, after heat preservation is completed, the steel belt is straightened using a roller straightening machine, and the surface of the steel belt is shot blasted, after heat preservation is completed, the steel belt is accurately straightened using a roller straightening machine to eliminate the bending deformation generated during heat treatment, and then the surface of the steel belt is shot blasted to introduce a beneficial compressive stress layer and slightly harden the surface, which not only improves the flatness of the steel belt, but also effectively improves its fatigue resistance and overall toughness.

[0019] Reference Figure 1 Example Two A high-toughness steel belt heat treatment quenching process is proposed in this embodiment, which includes the following steps: S1: Pretreatment of steel strips. First, clean the steel strips by soaking them in clean water and scrubbing them to remove impurities and residues. In the pretreatment step, the steel strips are soaked in clean water and scrubbed to thoroughly remove impurities such as oil, oxides, etc. on the surface and in the gaps. This creates a clean surface condition for subsequent heat treatment, prevents impurities from affecting the transformation of the steel strip structure or causing defects at high temperatures, and improves the toughness and stability of the final product. S2: Steel strip heating: Use a continuous protective atmosphere furnace with the temperature set at 950°C to heat the steel strip. For thick or wide steel strips, multi-zone heating can be used to ensure that the core reaches the required temperature. An endothermic atmosphere is used to prevent decarburization and oxidation on the steel strip surface. Each centimeter of steel strip needs to be heated for 15 minutes. A continuous protective atmosphere furnace is used for heating and precise temperature control to ensure that the steel strip is evenly heated to the required temperature. For thick and wide steel strips, a multi-zone heating strategy is implemented to ensure that the core temperature fully reaches the standard. At the same time, an endothermic atmosphere is used to strictly protect the steel strip surface, effectively preventing decarburization and oxidation, laying the foundation for obtaining a uniform and refined internal structure and good toughness. S3: Cooling the steel strip. Use rapid quenching oil to cool the steel strip. Immerse the steel strip in the rapid quenching oil and strictly control the temperature of the rapid quenching oil to keep it at 80°C. Use rapid quenching oil for cooling and strictly control the oil temperature to ensure that the steel strip obtains an appropriate cooling rate during the quenching process, promoting the full transformation of austenite to high-strength martensite. At the same time, it reduces the risk of excessive internal stress or poor structure caused by too fast or too slow cooling, optimizes the quenching effect and supports subsequent toughness improvement. S4: Cleaning of steel strips. Immediately after quenching, thoroughly clean the quenching oil or polymer residues on the surface of the steel strip to prepare for tempering and prevent the generation of oil smoke or pollution during tempering. Immediately after quenching, thoroughly clean the surface of the steel strip to completely remove the quenching oil or polymer residues to prevent these residues from generating oil smoke and polluting the environment during the subsequent high-temperature tempering process or adhering to the surface of the steel strip to affect the tempering uniformity, ensuring that the tempering process proceeds smoothly under clean conditions. S5: Tempering of the steel strip. The steel strip is tempered again in a continuous tempering furnace. Medium-high temperature tempering is adopted. The temperature range is usually 550℃ to ensure that the core is fully tempered. The time is 2 hours. After tempering, air cooling is performed. The quenched steel strip is tempered in a continuous tempering furnace at medium-high temperature. This temperature range can effectively adjust the microstructure of the quenched martensite, significantly reduce its brittleness and improve toughness. At the same time, sufficient time is guaranteed for the core of the steel strip to fully complete the tempering transformation. Air cooling after tempering further stabilizes the microstructure, and ultimately significantly improves the overall toughness of the steel strip. S6: Steel strip heat preservation, when the steel strip is cooled to 150℃, heat preservation is carried out, the heat preservation time is 2.5 hours, the heat preservation is carried out when the steel strip is cooled to a certain temperature interval, so that the internal organization of the steel strip is fully completed at this temperature and part of the stress is released, the heat preservation process helps to further stabilize the organization structure and refine the grain, thereby effectively improving the toughness and dimensional stability of the steel strip; S7: Steel strip post-treatment, after the heat preservation is completed, the steel strip is straightened by using a roller straightening machine, and the surface of the steel strip is then shot blasted, after the heat preservation is completed, the steel strip is precisely straightened by using a roller straightening machine to eliminate the bending deformation generated in the heat treatment process, and then the surface of the steel strip is shot blasted to introduce a beneficial compressive stress layer and slightly harden the surface, which not only improves the flatness of the steel strip, but also effectively improves the fatigue resistance and overall toughness of the steel strip.

[0020] Reference Figure 1 Example Three A high-toughness steel strip heat treatment quenching process is provided in this embodiment, which includes the following steps: S1: Steel strip pretreatment, first clean the steel strip, immerse the steel strip in clean water and brush it, remove impurities and residues, immerse the steel strip in clean water and brush it in the pretreatment step, thoroughly remove oil stains, oxides and other impurities and residues on the surface and gaps, create clean surface conditions for subsequent heat treatment, prevent impurities from affecting the steel strip organization transformation or causing defects at high temperatures, and improve the stability of the toughness of the final product; S2: Steel strip heating, use a continuous protective atmosphere furnace, set the temperature to 800℃, heat the steel strip, for thick or wide steel strips, use multi-zone heating to ensure that the core reaches the temperature, use endothermic atmosphere to prevent decarburization and oxidation of the steel strip surface, heat each centimeter of steel strip for 10 minutes, use a continuous protective atmosphere furnace for heating and precise temperature control to ensure uniform heating of the steel strip to the required temperature, use multi-zone heating strategy for thick and wide steel strips to ensure that the core temperature fully meets the standards, and use endothermic atmosphere to strictly protect the steel strip surface, effectively prevent decarburization and oxidation, and lay a foundation for obtaining uniform and refined internal organization and good toughness; S3: Steel strip cooling, use rapid quenching oil to cool the steel strip, immerse the steel strip in rapid quenching oil, strictly control the temperature of the rapid quenching oil, control the temperature at 40℃, use rapid quenching oil for cooling and strictly control the oil temperature, ensure that the steel strip obtains appropriate cooling speed in the quenching process, promote the full transformation of austenite to high-strength martensite, and reduce the risk of excessive internal stress or poor organization caused by too fast or too slow cooling, optimize the quenching effect to support the subsequent toughness improvement; S4: Steel belt cleaning, immediately after quenching, thoroughly clean the quenching oil or polymer residues on the surface of the steel belt, prepare for tempering, prevent oil smoke or pollution during tempering, immediately after quenching, thoroughly clean the surface of the steel belt, completely remove the quenching oil or polymer residues, avoid these residues producing oil smoke pollution environment or adhering to the surface of the steel belt affecting the uniformity of tempering during subsequent high temperature tempering process, ensure that the tempering process is carried out smoothly under clean conditions; S5: Steel belt tempering, using continuous tempering furnace to temper the steel belt again, using medium-high temperature tempering, the temperature range is usually 400℃, ensuring that the core is fully tempered, the time is 1 hour, after tempering, air cooling, in the continuous tempering furnace, medium-high temperature tempering is carried out on the quenched steel belt, which can effectively adjust the microstructure of quenched martensite, significantly reduce its brittleness and improve its toughness, and at the same time, enough time is ensured to complete the tempering transformation of the core of the steel belt, and the microstructure is further stabilized after air cooling after tempering, which significantly improves the overall toughness of the steel belt; S6: Steel belt heat preservation, when the steel belt cools to 100℃, heat preservation is carried out, the heat preservation time is 1 hour, when the steel belt cools to a certain temperature range, heat preservation treatment is carried out, so that the internal structure of the steel belt fully completes the transformation and releases part of the stress at this temperature, which helps to further stabilize the microstructure and refine the grains, thereby effectively improving the toughness and dimensional stability of the steel belt; S7: Steel belt post-treatment, after heat preservation, the steel belt is straightened by using a roller straightening machine, and the surface of the steel belt is shot blasted, after heat preservation, the steel belt is accurately straightened by using a roller straightening machine to eliminate the bending deformation generated during heat treatment, and then the surface of the steel belt is shot blasted to introduce beneficial compressive stress layer and slightly harden the surface, which not only improves the flatness of the steel belt, but also effectively improves the fatigue resistance and overall toughness of the steel belt.

[0021] Reference Figure 1 Example four In this embodiment, a high toughness steel belt heat treatment quenching process is proposed, which includes the following steps: S1: Steel belt pretreatment, first, the steel belt is cleaned by immersing it in clean water and brushing it, removing impurities and residues, in the pretreatment step, the steel belt is immersed in clean water and brushed, thoroughly removing oil stains, oxides and other impurities on the surface and in the gaps, creating clean surface conditions for subsequent heat treatment, preventing impurities from affecting the microstructure transformation of the steel belt or producing defects at high temperature, and improving the stability of the toughness of the final product; S2: Steel strip heating, using a continuous protective atmosphere furnace, set the temperature at 900, heat the steel strip, for thick or wide steel strip, can use multi-zone heating, to ensure the core temperature, using endothermic atmosphere, to prevent the steel strip surface decarburization and oxidation, each centimeter of steel strip needs to be heated for 13 minutes, using a continuous protective atmosphere furnace to heat and accurately control the temperature, to ensure that the steel strip is uniformly heated to the required temperature, for thick and wide steel strip, implement multi-zone heating strategy, to ensure that the core temperature is fully up to standard, while using endothermic atmosphere to strictly protect the steel strip surface, effectively prevent decarburization and oxidation, to lay the foundation for obtaining uniform and refined internal organization and good toughness; S3: Steel strip cooling, using rapid quenching oil to cool the steel strip, immersing the steel strip in the rapid quenching oil, strictly controlling the temperature of the rapid quenching oil, controlling the temperature at 65℃, using rapid quenching oil to cool and strictly controlling the oil temperature, to ensure that the steel strip obtains appropriate cooling speed during quenching, to promote the full transformation of austenite to high-strength martensite, while reducing the risk of excessive internal stress or poor organization caused by too fast or too slow cooling, optimizing the quenching effect to support subsequent toughness improvement; S4: Steel strip cleaning, immediately after quenching, thoroughly clean the quenching oil or polymer residues on the surface of the steel strip, to prepare for tempering, to prevent oil smoke or pollution during tempering, immediately after quenching, thoroughly clean the surface of the steel strip, completely remove the quenching oil or polymer residues, to avoid these residues producing oil smoke pollution environment or adhering to the steel strip surface affecting the uniformity of tempering during subsequent high-temperature tempering, to ensure that the tempering process proceeds smoothly under clean conditions; S5: Steel strip tempering, again using a continuous tempering furnace to temper the steel strip, using medium-high temperature tempering, the temperature range is usually 450℃, to ensure that the core is fully tempered, the time is 1.5 hours, after tempering, air cooling, in the continuous tempering furnace, medium-high temperature tempering is carried out on the quenched steel strip, this temperature range can effectively adjust the organization structure of quenched martensite, significantly reduce its brittleness and improve its toughness, while ensuring sufficient time for the steel strip core to fully complete the tempering transformation, air cooling after tempering further stabilizes the organization, finally significantly improves the overall toughness of the steel strip; S6: Steel strip holding, when the steel strip cools to 150℃, holding for 2 hours, holding when the steel strip cools to a certain temperature range, to make the internal organization of the steel strip fully complete the transformation and release part of the stress at this temperature, this holding process helps to further stabilize the organization structure and refine the grains, thereby effectively improving the toughness and dimensional stability of the steel strip; S7: Steel strip post-processing, after the completion of heat preservation, the last straightening is performed using a roller straightening machine, and shot blasting is performed on the surface of the steel strip. After the completion of heat preservation, the steel strip is first accurately straightened using a roller straightening machine to eliminate the bending deformation generated during the heat treatment process, and then shot blasting is performed on the surface of the steel strip to introduce a beneficial compressive stress layer into the surface layer of the steel strip and slightly harden the surface. This not only improves the flatness of the steel strip, but also effectively improves the fatigue resistance and overall toughness of the steel strip.

[0022] Referring to Figure 1 Example Five A high-toughness steel strip heat treatment quenching process is proposed in this embodiment, including the following steps: S1: Steel strip pretreatment, first clean the steel strip by immersing it in clean water and brushing it, removing impurities and residues. In the pretreatment step, the steel strip is immersed in clean water and brushed to thoroughly remove oil stains, oxides and other impurities from the surface and gaps, creating clean surface conditions for subsequent heat treatment, preventing impurities from affecting the microstructure transformation or causing defects at high temperatures, and improving the stability of the toughness of the final product; S2: Steel strip heating, using a continuous protective atmosphere furnace, set the temperature to 880°C, heat the steel strip. For thick or wide steel strips, multi-zone heating can be used to ensure that the core reaches the temperature. Use endothermic atmosphere to prevent decarburization and oxidation of the steel strip surface. Each centimeter of steel strip requires 10 minutes of heating. Use a continuous protective atmosphere furnace for heating and precise temperature control to ensure uniform heating of the steel strip to the required temperature. For thick and wide steel strips, implement a multi-zone heating strategy to ensure that the core temperature fully meets the standards. At the same time, use endothermic atmosphere to tightly protect the surface of the steel strip, effectively preventing decarburization and oxidation. This lays the foundation for obtaining uniform and refined internal microstructure and good toughness. S3: Steel strip cooling, using rapid quenching oil to cool the steel strip, immersing the steel strip in rapid quenching oil, strictly controlling the temperature of the rapid quenching oil to 70°C. Use rapid quenching oil for cooling and strictly control the oil temperature to ensure that the steel strip obtains an appropriate cooling speed during quenching, promoting the full transformation of austenite to high-strength martensite, while reducing the risk of excessive internal stress or poor microstructure caused by excessive or insufficient cooling. Optimize the quenching effect to support subsequent toughness improvement. S4: Steel strip cleaning, immediately after quenching, thoroughly clean the steel strip surface of quenching oil or polymer residues to prepare for tempering, preventing oil smoke or pollution during tempering. Immediately after quenching, thoroughly clean the surface of the steel strip to completely remove quenching oil or polymer residues. Avoid these residues producing oil smoke pollution in the subsequent high-temperature tempering process or adhering to the steel strip surface affecting the uniformity of tempering, ensuring that the tempering process proceeds smoothly under clean conditions. S5: Steel strip tempering, the steel strip is tempered again by using a continuous tempering furnace, high temperature tempering is adopted, the temperature range is generally 480 DEG C, the core is fully tempered, the time is 1 hour, and air cooling is performed after tempering is completed. The quenched steel strip is tempered at a high temperature in the continuous tempering furnace, the temperature range can effectively adjust the structure of quenched martensite, significantly reduce the brittleness and improve the toughness, and sufficient time is ensured to fully complete the tempering transformation of the core of the steel strip. After tempering, air cooling further stabilizes the structure, and the comprehensive toughness of the steel strip is significantly improved; S6: Steel strip heat preservation, when the steel strip is cooled to 140 DEG C, heat preservation is performed, the heat preservation time is 2 hours, and the steel strip is heat preserved when the steel strip is cooled to a specific temperature range, so that the internal structure of the steel strip is fully transformed and part of stress is released at the temperature. The heat preservation process helps to further stabilize the structure, refine the grains, and effectively improve the toughness and dimensional stability of the steel strip. S7: Steel strip post-treatment, after heat preservation is completed, the steel strip is straightened by using a roller straightening machine, and the surface of the steel strip is shot blasted, the steel strip is accurately straightened by using a roller straightening machine after heat preservation is completed, and the bending deformation generated in the heat treatment process is eliminated. Subsequently, the surface of the steel strip is shot blasted, a beneficial compressive stress layer is introduced on the surface layer of the steel strip, and the surface is slightly hardened, so that the flatness of the steel strip is improved, and the fatigue resistance and overall toughness of the steel strip are effectively improved.

[0023] Compared with the conventional high-toughness steel strip and the high-toughness steel strips prepared in examples one to five, the high-toughness steel strips prepared in examples one to five have the following table:

[0024] As shown in the above table, the high-toughness steel strip heat treatment quenching process provided by the application has obvious improvement, and the second implementation is the best embodiment.

[0025] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited to this. Any person skilled in the art can make equivalent replacements or changes to the technical solution and the inventive concept of the application within the technical range disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A high toughness steel strip heat treatment quenching process, characterized in that: The following steps are involved: S1: steel strip pretreatment; S2: steel strip heating; S3: steel strip cooling; S4: Steel strip cleaning; S5: steel strip tempering; S6: Steel belt insulation; S7: post-processing of steel strip.

2. A high toughness steel strip heat treatment quenching process according to claim 1, characterized in that: In the step S1, the steel strip is first cleaned by immersing the steel strip in clean water and scrubbing the inner side thereof to remove impurities and residues.

3. The high-toughness steel strip heat treatment and quenching process according to claim 1, characterized in that: In the S2 step, a continuous protective atmosphere furnace is used to set the temperature at 800°C-950°C to heat the steel strip. For thick or wide steel strips, multi-zone heating can be used to ensure that the core reaches the temperature. An endothermic atmosphere is used to prevent decarburization and oxidation on the surface of the steel strip. Each centimeter of steel strip needs to be heated for 10-15 minutes.

4. A high toughness steel strip heat treatment quenching process according to claim 1, characterized in that: In the step S3, the steel strip is cooled using rapid quenching oil. The steel strip is immersed in the rapid quenching oil, and the temperature of the rapid quenching oil is strictly controlled to be between 40°C and 80°C.

5. The high-toughness steel strip heat treatment and quenching process according to claim 1, characterized in that: In the step S4, the quenching oil or polymer residue on the surface of the steel strip is immediately and thoroughly cleaned after quenching to prepare for tempering and prevent the generation of oil smoke or pollution during tempering.

6. A high toughness steel strip heat treatment and quenching process according to claim 1, characterized in that: In the step S5, the steel strip is tempered again in a continuous tempering furnace, using medium-high temperature tempering, typically in the range of 400° C. to 550° C., to ensure that the core is fully tempered for 1-2 hours, and air cooling is performed after tempering is completed.

7. The high-toughness steel strip heat treatment and quenching process according to claim 1, characterized in that: In the step S6, when the steel strip is cooled to 100° C.-150° C., it is kept warm for 1-2.5 hours.

8. The high-toughness steel strip heat treatment and quenching process according to claim 1, characterized in that: In the step S7, after the heat preservation is completed, a roller straightener is used to straighten the steel strip, and then the surface of the steel strip is shot peened.

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