Spring steel 60si2mn cold rolled wide strip and method of manufacturing same

Abstract

The embodiment of the application provides a spring steel 60Si2Mn cold-rolled wide steel strip and a manufacturing method thereof, and relates to the field of spring steel 60Si2Mn. The spring steel 60Si2Mn cold-rolled wide steel strip can improve the problems of rolling inactivity, edge cracking and strip breakage in the cold rolling process. The spring steel 60Si2Mn cold-rolled wide steel strip comprises the following steps: strip straightening, hot-rolled wide steel strip pickling, first annealing, first cold rolling, the steel coil is controlled at 70-80 DEG C in the first cold rolling, the surface temperature of the rolled steel coil is controlled at 50-60 DEG C, the single pass reduction rate is controlled at 10.0%-18.0%, the total cold rolling deformation rate is controlled at 40.0%-48.0%, and the total cold rolling deformation amount is controlled at 1.0mm-3.0mm. After three times of annealing heat treatment and twice cold rolling, the cold-rolled wide steel strip has excellent stamping processing performance. The first cold rolling makes the surface temperature of the steel strip reach 50-60 DEG C in the first pass rolling, which is beneficial to avoiding brittle strip breakage in the cold rolling.

Description

Technical Field

[0001] This invention relates to the field of spring steel 60Si2Mn, and more specifically, to a cold-rolled wide strip of spring steel 60Si2Mn and its manufacturing method. Background Technology

[0002] 60Si2Mn cold-rolled spring steel strip, after stamping and heat treatment, possesses a high elastic limit, high ultimate strength, and good fatigue resistance. It is widely used in the manufacture of components such as helical springs, spring retainers, spring washers, and spring clips.

[0003] The main process flow for cold-rolled wide strip of spring steel 60Si2Mn is as follows: hot-rolled wide strip, 800-1300mm wide → pickling → first annealing → first cold rolling → second annealing → second cold rolling → Nth spheroidizing annealing → Nth cold rolling → slitting → packaging and warehousing. Due to the high carbon and silicon content in spring steel 60Si2Mn, the following problems exist in its cold-rolled strip production: 1. High-silicon steel forms a denser iron oxide scale than conventional steel, making pickling more difficult; incomplete pickling affects the surface quality of the cold-rolled product; and the high silicon content makes rolling difficult. 2. Due to the high brittleness of the strip, edge cracks and even strip breakage are prone to occur during cold rolling, especially in the first pass. 3. Poor or uneven spheroidizing quality results in high deformation resistance during cold rolling, poor rolling stability, large thickness fluctuations, and difficulty in meeting high-precision dimensional requirements. Summary of the Invention

[0004] The present invention aims to provide, for example, a method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn, which can improve the problems of rolling blockage, edge cracking, and strip breakage that easily occur during the cold rolling process of cold-rolled wide strip of spring steel 60Si2Mn.

[0005] The present invention also aims to provide a cold-rolled wide strip of spring steel 60Si2Mn, which can improve the problems of rolling blockage, edge cracking and strip breakage that easily occur during the cold rolling process of 60Si2Mn cold-rolled wide strip of spring steel.

[0006] The embodiments of the present invention can be implemented as follows:

[0007] An embodiment of the present invention provides a method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn, comprising the following steps:

[0008] Strip straightening, hot-rolled wide strip pickling, first annealing, first cold rolling, second annealing, second cold rolling and third annealing;

[0009] The first cold rolling step includes: cold rolling a hot-rolled wide steel strip with a thickness of 2.5mm-6.0mm after the first annealing treatment, with the coiling temperature controlled at 70-80℃, the surface temperature of the rolled steel coil controlled at 50-60℃, the single-pass reduction rate controlled at 10.0%-18.0%, the total cold rolling deformation rate controlled at 40.0%-48.0%, and the total cold rolling deformation controlled at 1.0mm-3.0mm.

[0010] In addition, the method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn provided in the embodiments of the present invention may also have the following additional technical features:

[0011] Optionally, after the first annealing treatment, the proportion of carbide structures with a diameter of 0.3-0.8 μm in the metallographic structure is ≥92%; after the second annealing treatment, the proportion of carbide structures with a diameter of 0.2-0.6 μm in the structure is ≥95%; and after the third annealing treatment, the proportion of carbide structures with a diameter of 0.2-0.6 μm in the structure is ≥98%.

[0012] Optionally, the pickling step of the hot-rolled wide steel strip includes: a pickling speed of 30m / min-50m / min, an acid concentration of 110g / l-220g / L, and an acid temperature of 80℃-85℃.

[0013] Optionally, the first annealing step includes: holding at 760℃-770℃ for 4 hours, then lowering to 740℃ at 10℃ / s and holding for 16 hours, cooling in the furnace to 640℃-650℃, changing the cooling hood for air cooling, cooling to 350℃-380℃, and then spray cooling to 90-100℃ before being removed from the furnace.

[0014] Optionally, the first cold rolling step further includes: controlling the emulsion temperature at 50-55℃, controlling the emulsion mass concentration at 3.0%-3.5%, controlling the rolling speed at 300m / min-400m / min, controlling the rolling force at 15000KN-21000KN, controlling the exit tension at 220KN-350KN, controlling the inlet tension at 180KN-250KN, and ensuring that the exit tension is greater than the inlet tension.

[0015] Optionally, the second annealing step includes: annealing at 740℃-750℃, holding at that temperature for 14h-17h, cooling in the furnace to 640℃-650℃, changing the cooling hood for air cooling to 350℃-380℃, and then spray cooling to 80℃-90℃ before exiting the furnace.

[0016] Optionally, after the second annealing treatment, the tensile strength is controlled at 650MPa-720MPa, the yield strength is controlled at 550MPa-630Pa, the elongation is controlled at 25.0%-35.0%, and the Brinell hardness is 190-210HB.

[0017] Optionally, the second cold rolling step includes: controlling the total cold rolling deformation rate at 35.0%-45.0%; controlling the emulsion temperature at 50-55℃, the emulsion mass concentration at 3.0%-3.5%, the rolling speed at 350m / min-500m / min, and the rolling force at 14000KN-19000KN; controlling the exit tension at 150KN-250KN, and the inlet tension at 120KN-220KN; with the exit tension being greater than the inlet tension.

[0018] Optionally, the third annealing step includes: annealing at a temperature of 730℃-740℃, holding at that temperature for 12h-15h, cooling in the furnace to 580℃-600℃, changing the cooling hood for air cooling to 340℃-360℃, and then spray cooling to 80℃-85℃ before exiting the furnace.

[0019] An embodiment of the present invention also provides a cold-rolled wide strip of spring steel 60Si2Mn. It is manufactured using a method for producing cold-rolled wide strip of spring steel 60Si2Mn, and the strip comprises the following components: C: 0.58-0.64%, Mn: 0.70-0.90%, S≤0.010%, P≤0.020%, Si: 1.6-2.0%, Cr: 0.20-0.35%, Ni: 0.15-0.25%, Cu: ≤0.20%, Als: 0.010-0.060%.

[0020] The beneficial effects of the cold-rolled wide strip of spring steel 60Si2Mn and its manufacturing method according to embodiments of the present invention include, for example:

[0021] The manufacturing method of cold-rolled wide strip of spring steel 60Si2Mn includes the following steps: strip straightening; pickling of hot-rolled wide strip; first annealing; first cold rolling; the first cold rolling step includes: cold rolling the hot-rolled wide strip with a thickness of 2.5mm-6.0mm after the first annealing treatment, with the coiling temperature controlled at 70-80℃, the surface temperature of the rolled coil controlled at 50-60℃, the single-pass reduction rate controlled at 10.0%-18.0%, the total cold rolling deformation rate controlled at 40.0%-48.0%, and the total cold rolling deformation controlled at 1.0mm-3.0mm; second annealing; second cold rolling; third annealing.

[0022] After three annealing heat treatments and two cold rolling processes, a uniformly distributed granular pearlite microstructure of 60Si2Mn spring steel cold-rolled wide strip is obtained, ensuring excellent stamping performance. The first cold rolling process involves cold rolling the pickled hot-rolled wide strip, ensuring the strip surface temperature reaches 50-60℃ during the first rolling pass. This helps prevent brittle breakage during cold rolling, achieving stable rolling, guaranteeing product quality, and avoiding edge cracks and strip breakage.

[0023] The cold-rolled wide strip of spring steel 60Si2Mn, manufactured using the above-mentioned method, can improve the problems of rolling blockage, edge cracking, and strip breakage that easily occur during the cold rolling process of 60Si2Mn cold-rolled wide strip of spring steel. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the steps of the method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn provided in this embodiment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0030] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0031] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0032] The following is combined Figure 1 The manufacturing method of cold-rolled wide strip of spring steel 60Si2Mn provided in this embodiment is described in detail.

[0033] Please refer to Figure 1 The present invention provides a method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn, comprising the following steps:

[0034] Step S1, strip straightening;

[0035] Step S2: Pickling of hot-rolled wide steel strip;

[0036] Step S3, first annealing;

[0037] Step S4, First Cold Rolling; The first cold rolling process includes: cold rolling the hot-rolled wide steel strip with a thickness of 2.5mm-6.0mm after the first annealing treatment, controlling the coiling temperature at 70-80℃, the surface temperature of the rolled steel coil at 50-60℃, the single-pass reduction rate at 10.0%-18.0%, the total cold rolling deformation rate at 40.0%-48.0%, and the total cold rolling deformation at 1.0mm-3.0mm;

[0038] Step S5, second annealing;

[0039] Step S6, second cold rolling;

[0040] Step S7, third annealing.

[0041] Before entering the pickling bath, the strip steel is first straightened by a nine-roll straightener. The first annealing spheroidizes the steel, preparing it well for cold rolling. The first annealing and the first cold rolling are to prevent cracking during the cold rolling process. The second annealing eliminates work hardening caused by cold rolling and further spheroidizes the steel. The second cold rolling achieves stable rolling and high-precision thickness quality control.

[0042] The first cold rolling process involves using a 1450mm single-stand six-high reversible rolling mill to cold roll the pickled 60Si2Mn spring steel hot-rolled wide strip. After the first annealing treatment at 90-100℃, the steel coil is immediately transferred to the cold rolling mill for cold rolling. This ensures that the surface temperature of the strip reaches 50-60℃ during the first rolling pass, which helps avoid brittle strip breakage during cold rolling. Stable rolling is achieved, ensuring product quality and further preventing edge cracks and strip breakage. This process enables continuous and stable cold rolling of 60Si2Mn spring steel wide strip, guaranteeing dimensional accuracy and product quality.

[0043] Strip straightening and pickling of hot-rolled wide steel strips are for hot-rolled wide steel strips with a thickness of 2.5mm-6.0mm and a width of 900mm-1300mm.

[0044] Before entering the acid bath, the strip steel is first straightened by a nine-roll straightener. The parameters of the straightening rolls are shown in Table 1.

[0045] Table 1 Straightening Roller Press-down Parameters

[0046]

[0047] Straightening loosens the iron oxide scale on the surface of the strip, further ensuring that the iron oxide scale on the surface of the hot-rolled wide strip of spring steel 60Si2Mn is thoroughly cleaned by pickling, thus guaranteeing the surface quality of the subsequent cold-rolled wide strip of spring steel 60Si2Mn.

[0048] In this embodiment, after the first annealing treatment in step S3, the proportion of carbide structures with a diameter of 0.3-0.8 μm in the metallographic structure is ≥92%; after the second annealing treatment in step S5, the proportion of carbide structures with a diameter of 0.2-0.6 μm in the structure is ≥95%; after the third annealing treatment in step S7, the proportion of carbide structures with a diameter of 0.2-0.6 μm in the structure is ≥98%.

[0049] After the first annealing treatment in step S3, the Brinell hardness of the hot-rolled wide strip of spring steel 60Si2Mn is 190-215HB, and the proportion of carbide microstructure with a diameter of 0.3-0.8um is ≥92%.

[0050] After the second spheroidizing annealing in step S5, the tensile strength is controlled at 650MPa-720MPa, the yield strength is controlled at 550MPa-630Pa, the elongation is controlled at 25.0%-35.0%, the Brinell hardness is 190-210HB, and the proportion of carbide structures with a diameter of 0.2-0.6um in the microstructure is ≥95%.

[0051] After the third annealing treatment in step S7, the tensile strength of spring steel 60Si2Mn is controlled at 550MPa-680MPa, the yield strength is controlled at 400MPa-460MPa, the elongation is controlled at 27.0%-34.0%, the Vickers hardness is controlled at 180-200HV, and the proportion of carbide microstructure with a diameter of 0.2-0.6um is ≥98%.

[0052] In this embodiment, step S2, pickling of hot-rolled wide steel strip, includes: pickling speed of 30m / min-50m / min, acid concentration of 110g / l-220g / L, and acid temperature of 80℃-85℃.

[0053] The hot-rolled wide strip of spring steel 60Si2Mn is pickled with hydrochloric acid using a push-pull pickling line. No oil is applied to the surface of the steel coil during the pickling process to prevent the formation of black spots during the subsequent annealing process, thereby further ensuring the surface quality of the cold-rolled wide strip of spring steel 60Si2Mn.

[0054] In this embodiment, the first annealing step S3 includes: holding at 760℃-770℃ for 4 hours, then lowering to 740℃ at 10℃ / s and holding for 16 hours, cooling with the furnace to 640℃-650℃, changing the cooling hood for air cooling, cooling to 350℃-380℃, and then spray cooling to 90-100℃ before exiting the furnace.

[0055] Annealing was performed using a full-hydrogen bell-type annealing furnace. The first annealing process involved spheroidizing annealing of the hot-rolled 60Si2Mn spring steel strip, which spheroidized the lamellar pearlite in the hot-rolled microstructure, resulting in a certain quantity and size of granular pearlite. This reduced the hardness and strength of the steel strip while improving its plasticity. This ensured that the annealed hot-rolled 60Si2Mn spring steel strip possessed good microstructure and properties, preparing it for cold rolling.

[0056] In this embodiment, step S4, the first cold rolling, further includes: controlling the emulsion temperature at 50-55℃, controlling the emulsion mass concentration at 3.0%-3.5%, controlling the rolling speed at 300m / min-400m / min, controlling the rolling force at 15000KN-21000KN, controlling the exit tension at 220KN-350KN, controlling the inlet tension at 180KN-250KN, and ensuring that the exit tension is greater than the inlet tension.

[0057] The emulsion lubrication parameters were optimized during the first cold rolling process. A strategy was adopted where the exit tension was greater than the inlet tension. The first cold rolling process ensured stable rolling, guaranteeing product quality and further preventing edge cracks and strip breakage.

[0058] In this embodiment, step S5, the second annealing, includes: annealing at a temperature of 740℃-750℃, holding at that temperature for 14h-17h, cooling in the furnace to 640℃-650℃, changing the cooling hood for air cooling, cooling to 350℃-380℃, and then spray cooling to 80℃-90℃ before exiting the furnace.

[0059] The second annealing treatment was carried out in a full-hydrogen bell-type annealing furnace. The second annealing eliminated the work hardening phenomenon caused by the first cold rolling and further made the microstructure of the 60Si2Mn cold-rolled wide strip of spring steel more uniform, preparing it for subsequent cold rolling.

[0060] In this embodiment, after the second annealing treatment in step S5, the tensile strength is controlled at 650MPa-720MPa, the yield strength is controlled at 550MPa-630Pa, the elongation is controlled at 25.0%-35.0%, and the Brinell hardness is 190-210HB.

[0061] After the second spheroidizing annealing, the tensile strength is controlled at 650MPa-720MPa, the yield strength is controlled at 550MPa-630Pa, the elongation is controlled at 25.0%-35.0%, the Brinell hardness is 190-210HB, and the proportion of carbide structures with a diameter of 0.2-0.6um in the microstructure is ≥95%.

[0062] In this embodiment, step S6, the second cold rolling, includes: controlling the total cold rolling deformation rate at 35.0%-45.0%; controlling the emulsion temperature at 50-55℃, the emulsion mass concentration at 3.0%-3.5%, the rolling speed at 350m / min-500m / min, and the rolling force at 14000KN-19000KN; controlling the exit tension at 150KN-250KN, and the inlet tension at 120KN-220KN; the exit tension is greater than the inlet tension.

[0063] The second cold rolling process enables stable rolling, ensuring product quality and preventing strip breakage. Through the second cold rolling, high-precision thickness control is achieved, with the thickness tolerance after cold rolling controlled within -10μm to +10μm, resulting in a smooth and flat steel strip surface.

[0064] After the second spheroidizing annealing, the 60Si2Mn spring steel wide strip was cold-rolled again using a 1450mm single-stand six-high reversible mill; the total cold rolling deformation rate was controlled between 35.0% and 45.0%. Emulsion lubrication was used for the second cold rolling. The rolling tension was set using a strategy where the exit tension was greater than the inlet tension.

[0065] In this embodiment, step S7, the third annealing, includes: annealing at a temperature of 730℃-740℃, holding at that temperature for 12h-15h, cooling in the furnace to 580℃-600℃, changing the cooling hood for air cooling, cooling to 340℃-360℃, and then spray cooling to 80℃-85℃ before exiting the furnace.

[0066] The third annealing treatment was carried out using a full-hydrogen bell-type annealing furnace. After the third annealing treatment, the tensile strength of the spring steel 60Si2Mn was controlled at 550MPa-680MPa, the yield strength at 400MPa-460MPa, the elongation at 27.0%-34.0%, the Vickers hardness at 180-200HV, and the proportion of carbide microstructure with a diameter of 0.2-0.6um ≥98%. After all technical indicators passed the inspection and judgment, the steel was packaged and put into storage.

[0067] The third annealing process involves subjecting the cold-rolled wide strip of spring steel 60Si2Mn to a third spheroidizing annealing treatment, resulting in a uniformly distributed granular pearlite microstructure. The Vickers hardness is controlled at 180-200 HV, and the annealing spheroidization rate is controlled at ≥98%. This ensures that the cold-rolled wide strip of spring steel 60Si2Mn possesses superior stamping performance, facilitating smooth stamping and deformation processing and better meeting user needs.

[0068] According to the manufacturing method of cold-rolled wide strip of spring steel 60Si2Mn provided in this embodiment, the working principle of the manufacturing method of cold-rolled wide strip of spring steel 60Si2Mn is as follows: after three annealing heat treatments and two cold rolling processes, a uniformly distributed granular pearlite structure of cold-rolled wide strip of spring steel 60Si2Mn is obtained, with a Vickers hardness of 180-200HV, an annealing spheroidization rate ≥98%, and a thickness dimensional tolerance controlled within -10μm to +10μm. This ensures that the cold-rolled wide strip of spring steel 60Si2Mn has excellent stamping processing performance, which is conducive to the smooth implementation of stamping and deformation processing, and better meets the user's requirements for dimensional accuracy and product quality.

[0069] The method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn provided in this embodiment has at least the following advantages:

[0070] By optimizing the pickling process and setting straightening parameters, the surface quality of 60Si2Mn spring steel after pickling was improved.

[0071] By increasing the emulsion solubility and temperature, and optimizing cold rolling parameters, the surface temperature of the steel coil during cold rolling is guaranteed, thus reducing the phenomenon of strip breakage during cold rolling.

[0072] The heat treatment process is carried out using a designed all-hydrogen bell-type furnace annealing process, and the cold rolling process parameters are designed for a 1450mm single-stand six-roll reversible rolling mill. After the steel strip is annealed, it undergoes large deformation cold rolling, which elongates and breaks the pearlite grains, increases the number of crystal defects, and significantly increases the annealing driving energy, making the microstructure more uniform after annealing and having excellent dimensional accuracy.

[0073] High-silicon steel is produced through a single annealing process, first-pass cold rolling control, and overall cold rolling process control to prevent issues such as rolling blockage, edge cracking, and strip breakage during the cold rolling of 60Si2Mn. This also improves the surface quality of 60Si2Mn spring steel.

[0074] Embodiments of the present invention also provide a cold-rolled wide strip of spring steel 60Si2Mn. This strip is manufactured using a method for producing cold-rolled wide strip of spring steel 60Si2Mn, and comprises the following components: C: 0.58-0.64%, Mn: 0.70-0.90%, S≤0.010%, P≤0.020%, Si: 1.6-2.0%, Cr: 0.20-0.35%, Ni: 0.15-0.25%, Cu: ≤0.20%, Als: 0.010-0.060%.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn, characterized in that, Includes the following steps: Strip straightening, hot-rolled wide strip pickling, first annealing, first cold rolling, second annealing, second cold rolling and third annealing; The first cold rolling step includes: cold rolling a hot-rolled wide steel strip with a thickness of 2.5mm-6.0mm after the first annealing treatment; controlling the coiling temperature at 70-80℃; controlling the surface temperature of the rolled steel strip at 50-60℃; controlling the single-pass reduction rate at 10.0%-18.0%; controlling the total cold rolling deformation rate at 40.0%-48.0%; and controlling the total cold rolling deformation at 1.0mm-3.0mm. The second cold rolling step includes: controlling the total cold rolling deformation rate at 35.0%-45.0%; controlling the emulsion temperature at 50-55℃, the emulsion mass concentration at 3.0%-3.5%, the rolling speed at 350m / min-500m / min, and the rolling force at 14000KN-19000KN; controlling the exit tension at 150KN-250KN, and the inlet tension at 120KN-220KN; the exit tension is greater than the inlet tension.

2. The method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn according to claim 1, characterized in that: After the first annealing treatment, the proportion of carbide structures with a diameter of 0.3-0.8 μm in the metallographic structure is ≥92%; after the second annealing treatment, the proportion of carbide structures with a diameter of 0.2-0.6 μm in the structure is ≥95%; after the third annealing treatment, the proportion of carbide structures with a diameter of 0.2-0.6 μm in the structure is ≥98%.

3. The method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn according to claim 1, characterized in that, The pickling process for the hot-rolled wide steel strip includes: a pickling speed of 30m / min-50m / min, an acid concentration of 110g / l-220g / L, and an acid temperature of 80℃-85℃.

4. The method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn according to claim 1, characterized in that, The first annealing step includes: The furnace is kept at 760℃-770℃ for 4 hours, then cooled to 740℃ at a rate of 10℃ / s and kept at that temperature for 16 hours. It is then cooled in the furnace to 640℃-650℃, and the cooling hood is replaced for air cooling to 350℃-380℃. Finally, it is sprayed to cool to 90-100℃ before being removed from the furnace.

5. The method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn according to claim 1, characterized in that, The first cold rolling step also includes: The emulsion temperature is controlled at 50-55℃, the emulsion mass concentration is controlled at 3.0%-3.5%, the rolling speed is controlled at 300m / min-400m / min, the rolling force is controlled at 15000KN-21000KN, the exit tension is controlled at 220KN-350KN, the inlet tension is controlled at 180KN-250KN, and the exit tension is greater than the inlet tension.

6. The method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn according to claim 1, characterized in that, The second annealing step includes: The annealing temperature is 740℃-750℃, held for 14h-17h, cooled in the furnace to 640℃-650℃, then the cooling hood is replaced for air cooling to 350℃-380℃, and then sprayed to cool to 80℃-90℃ before being taken out of the furnace.

7. The method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn according to claim 6, characterized in that: After the second annealing treatment, the tensile strength is controlled at 650MPa-720MPa, the yield strength is controlled at 550MPa-630Pa, the elongation is controlled at 25.0%-35.0%, and the Brinell hardness is 190-210HB.

8. The method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn according to claim 1, characterized in that, The third annealing step includes: The annealing temperature is 730℃-740℃, held for 12h-15h, cooled in the furnace to 580℃-600℃, then the cooling hood is replaced for air cooling to 340℃-360℃, and then sprayed to cool to 80℃-85℃ before being taken out of the furnace.

9. A cold-rolled wide strip of spring steel 60Si2Mn, manufactured using the method for manufacturing cold-rolled wide strip of spring steel 60Si2Mn according to any one of claims 1-8, characterized in that, The 60Si2Mn cold-rolled wide spring steel strip comprises the following components: C: 0.58-0.64%, Mn: 0.70-0.90%, S≤0.010%, P≤0.020%, Si: 1.6-2.0%, Cr: 0.20-0.35%, Ni: 0.15-0.25%, Cu: ≤0.20%, Als: 0.010-0.060%.

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