High-strength anti-deformation light steel keel and preparation method thereof

Abstract

The invention relates to the technical field of building structure materials, in particular to a high-strength anti-deformation light steel keel and a preparation method thereof.The preparation method comprises the following steps that S1, burdening is conducted according to a preset raw material ratio, and an electric furnace is adopted for smelting to obtain a plate blank; s2, heating, heat preservation and multi-pass hot continuous rolling are conducted, then online accelerated cooling is conducted, and hot-rolled strip steel is obtained; s3, the hot-rolled strip steel cooled in the step S2 is coiled; s4, acid pickling is conducted to remove oxide scale, then cold rolling is conducted to the target thickness, and a cold-rolled steel strip is obtained; s5, continuous cold roll forming is conducted, and a keel semi-finished product is manufactured; s6, pre-strain is applied to the keel semi-finished product, and then low-temperature aging treatment is conducted; and S7, surface coating treatment is conducted, and a finished high-strength anti-deformation light steel keel product is obtained. According to the light steel keel and the manufacturing method thereof, through alloy component optimization, structure strengthening control and surface coating collaborative design, comprehensive improvement of the light steel keel in the aspects of high strength, deformation resistance and corrosion resistance is achieved.

Description

Technical Field

[0001] This invention relates to the field of building structural materials technology, and in particular to a high-strength, deformation-resistant light steel keel and its preparation method. Background Technology

[0002] As the modern construction industry continues to demand higher requirements for lightweight structures, ease of construction, and overall seismic performance, light steel keel has been widely used in ceiling, partition, roof, and light steel housing systems due to its advantages such as light weight, easy installation, energy saving, and environmental protection. In order to adapt to the changing usage environment and long-term service conditions, light steel keel not only needs to have good formability and dimensional stability, but also needs to take into account high strength, corrosion resistance, and deformation resistance.

[0003] However, existing light steel keels mostly use ordinary carbon steel or low-alloy steel as the base material, which still faces problems such as insufficient strength, poor long-dimensional stability, easy deformation, and poor coating adhesion in practical applications. Especially in thin-gauge, long-span, or complex installation scenarios, structural safety hazards such as keel warping, loosening of connection points, or corrosion failure are prone to occur. At the same time, current manufacturing processes are mostly concentrated on conventional continuous rolling and simple cold bending forming, lacking a systematic coupling of microalloy precipitation strengthening mechanisms, pre-strain aging treatment, and interface synergistic coating technology, making it difficult to achieve a synergistic improvement in high strength and deformation resistance. Therefore, there is an urgent need for a high-strength, deformation-resistant light steel keel and its manufacturing method to solve the above problems. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides a high-strength, deformation-resistant light steel keel and its preparation method.

[0005] A high-strength, deformation-resistant light steel keel and its preparation method are disclosed, comprising the following raw materials in weight percentages: C 0.05-0.15%, Si 0.10-0.35%, Mn 0.80-1.60%, P 0.025%, S 0.020%, Nb 0.015-0.045%, V 0.03-0.08%, Ti 0.01-0.04%, Cu 0.20-0.50%, Cr 0.15-0.40%, Al 0.015-0.050%, N 0.007%, Mo 0.05-0.20%, Ni 0.10-0.30%, with the balance being Fe.

[0006] Optionally, the cross-section of the light steel keel is C-shaped, U-shaped, or L-shaped, and its web or flange is provided with regularly distributed reinforcing ribs, embossed patterns, or weight-reducing holes.

[0007] A method for preparing a high-strength, deformation-resistant light steel keel includes the following steps: S1: The raw materials are batched according to the proportions described in claim 1, smelted in an electric furnace, and after LF ladle refining and RH vacuum degassing treatment, continuous casting is carried out to obtain a slab. S2: The slab is heated, kept at a constant temperature and hot rolled in multiple passes, followed by online accelerated cooling to obtain hot-rolled strip steel; S3: The hot-rolled strip steel cooled in S2 is coiled to obtain a hot-rolled coil; S4: Pickling is performed on the hot-rolled coil to remove iron oxide scale, and then cold rolling is performed to the target thickness to obtain cold-rolled steel strip; S5: The cold-rolled steel strip is continuously cold-bent to form a keel semi-finished product with a predetermined cross-sectional shape; S6: Apply pre-strain to the semi-finished keel and then perform low-temperature aging treatment to promote the formation of strengthening precipitates by micro-alloying elements and alloying elements in the raw materials; S7: The semi-finished keel after S6 aging treatment is surface coated and then finished to obtain a high-strength, deformation-resistant light steel keel finished product.

[0008] Optionally, S1 specifically includes: S11: Weigh each component according to the preset raw material ratio and place it in the electric furnace; S12: Smelting is carried out in an electric furnace, and the tapping temperature is controlled at 1620-1660℃; S13: Transfer the molten steel to the LF refining furnace for deoxidation and desulfurization under argon protection. The refining time is 25-45 minutes. S14: Transfer the refined molten steel into the RH vacuum circulation degassing device, control the vacuum degree to 50-100Pa, and the processing time is 15-25 minutes. S15: The treated molten steel is injected into the crystallizer for continuous casting, with the casting speed controlled at 1.2-1.6 m / min and the cooling water flow rate of the crystallizer at 120-180 m³ / h, to obtain a slab with a thickness of 150-220 mm.

[0009] Optionally, S2 specifically includes: S21: The slab is fed into a heating furnace, heated to 1180-1250℃, and held at that temperature for 1-3 hours; S22: The heated and heat-preserved slab is rolled in 9-12 passes, with the cumulative reduction rate of the last three passes not less than 40%, and the final rolling temperature controlled at 860-920℃. S23: The strip steel after final rolling is immediately subjected to laminar flow cooling, and the strip steel is cooled to 550-650℃ at a cooling rate of 15-40℃ / s to obtain hot-rolled strip steel with phase transformation structure.

[0010] Optionally, S3 specifically includes: S31: The strip head is fed into the coiler and wound into a coil under tension control to obtain a hot-rolled coil; S32: The hot-rolled coil is placed in air and subjected to self-tempering using residual heat.

[0011] Optionally, S4 specifically includes: S41: After the hot-rolled coil is uncoiled, it is guided through a hydrochloric acid pickling tank. The concentration of the hydrochloric acid is 12-18 wt%, the pickling temperature is 70-85℃, and the pickling time is 90-180 seconds, in order to remove the iron oxide scale on the surface of the hot-rolled coil. S42: After pickling, cleaning, and drying, the strip steel is subjected to multiple cold rolling passes with a total reduction rate of 50%-70% to obtain a cold-rolled steel strip with a thickness of 0.4-1.2mm.

[0012] Optionally, S5 specifically includes: S51: Uncoil the cold-rolled steel strip and straighten it using a straightening machine to eliminate poor strip shape; S52: The straightened steel strip is continuously fed into a cold bending forming unit consisting of 12-20 forming rollers. The profile of each forming roller changes sequentially, so that the steel strip is gradually bent at room temperature to form a continuous profile with a predetermined cross-sectional shape. S53: Using a flying saw or hydraulic punching and shearing machine, the continuous profile is dynamically cut to a set length to obtain the semi-finished keel.

[0013] Optionally, S6 specifically includes: S61: Place the semi-finished keel in a stretching machine and apply 0.8%-1.5% tensile plastic strain along its longitudinal direction; S62: Place the pre-strained keel semi-finished product in a continuous aging furnace and hold it at 300-380℃ for 45-90 minutes, then air cool to room temperature.

[0014] Optionally, S7 specifically includes: S71: The semi-finished keel after S6 treatment is degreased, washed with water, acid-washed and activated, and then washed and dried with water. The acid-washed and activated solution is a sulfuric acid solution with a concentration of 8-12wt%, and the treatment time is 30-90 seconds. S72: The pre-treated keel semi-finished product is immersed in a zinc-aluminum-magnesium alloy molten plating solution at 450-470℃ for 3-10 seconds. After being taken out, the coating thickness is controlled by an air knife and cooled to form a metal coating with a unit area weight of 120-275g / m². S73: Coat the keel with a metal plating with a chromium-free passivating agent or a water-based acrylic resin sealant with a thickness of 1-5 μm. S74: The coated keel is cut to length, straightened by pressure using a straightening machine to control straightness, inspected and packaged to obtain the finished high-strength, deformation-resistant light steel keel.

[0015] The beneficial effects of this invention are: This invention, by introducing multiple microalloying elements such as Nb, V, and Ti into light steel materials and controlling their content and smelting and refining process parameters, effectively promotes the precipitation of dispersed reinforcing phases such as carbides and nitrides, significantly improving the strength and deformation resistance of the base material while maintaining good formability. Simultaneously, through precise control of key hot working parameters such as final rolling temperature and cooling rate during rolling, a stable multiphase microstructure is obtained, giving the material excellent mechanical properties and dimensional stability, providing a good microstructure foundation for subsequent precision cold bending forming.

[0016] This invention introduces a combined effect of longitudinal pre-strain loading and low-temperature aging treatment after molding to further induce the precipitation of the second phase and eliminate residual stress, thereby improving the strength retention rate and anti-warping ability of the product during service. Combined with hot-dip galvanizing of zinc-aluminum-magnesium alloy and chromium-free passivation sealing treatment, it can significantly enhance the service life and surface protection performance of the finished product in humid and corrosive environments. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the process for preparing light steel keel according to an embodiment of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should also be noted that, to make the embodiments more comprehensive, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some well-known technologies; moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0020] It should be noted that the use of terms such as "an embodiment," "an embodiment," "an exemplary embodiment," and "some embodiments" in the specification indicates that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the art.

[0021] Generally, terms can be understood at least partly from their use in context. For example, depending at least partly on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or a combination of features, structures, or characteristics in a plural sense. Additionally, the term "based on" can be understood not necessarily to convey an exclusive set of factors, but rather, alternatively, depending at least partly on the context, to allow for the presence of other factors that are not necessarily explicitly described.

[0022] Example 1 like Figure 1 As shown, a high-strength, deformation-resistant light steel keel and its preparation method are made from the following raw materials by weight percentage: C 0.08%, Si 0.25%, Mn 1.30%, P 0.025%, S 0.020%, Nb 0.035%, V 0.05%, Ti 0.02%, Cu 0.35%, Cr 0.30%, Al 0.030%, N 0.007%, Mo 0.10%, Ni 0.25%, with the balance being Fe.

[0023] The cross-section of the light steel keel is C-shaped, and its web or flanges are provided with regularly distributed reinforcing ribs, embossed patterns or weight-reducing holes.

[0024] A method for preparing a high-strength, deformation-resistant light steel keel includes the following steps: S1: The raw materials are batched according to the proportions of claim 1, smelted in an electric furnace, and after LF ladle refining and RH vacuum degassing treatment, continuous casting is carried out to obtain a slab. S2: The slab is heated, held at a constant temperature and hot rolled in multiple passes, followed by online accelerated cooling to obtain hot-rolled strip with phase transformation structure; S3: The hot-rolled strip steel cooled in S2 is coiled to obtain a hot-rolled coil; S4: Pickling is performed on the hot-rolled coil to remove the iron oxide scale, and then cold rolling is performed to the target thickness to obtain cold-rolled steel strip; S5: The cold-rolled steel strip is continuously cold-bent to form a keel semi-finished product with a predetermined cross-sectional shape; S6: Apply pre-strain to the semi-finished keel and then perform low-temperature aging treatment to promote the formation of strengthening precipitates by micro-alloying elements and alloying elements in the raw materials, thereby improving strength and dimensional stability. S7: The semi-finished keel after S6 aging treatment is surface coated and then finished to obtain a high-strength, deformation-resistant light steel keel finished product.

[0025] S1 specifically includes: S11: Weigh each component according to the preset raw material ratio and place it in the electric furnace; S12: Smelting is carried out in an electric furnace, and the tapping temperature is controlled at 1640℃; S13: Transfer the molten steel to the LF refining furnace for deoxidation and desulfurization under argon protection. The refining time is 35 minutes. S14: Transfer the refined molten steel into the RH vacuum circulation degassing device, control the vacuum degree to 80Pa, and the processing time is 20 minutes. S15: The treated molten steel is injected into the crystallizer for continuous casting, with the casting speed controlled at 1.4 m / min and the cooling water flow rate of the crystallizer at 150 m³ / h, to obtain a slab with a thickness of 200 mm.

[0026] S2 specifically includes: S21: Send the slab into the heating furnace, heat it to 1220℃, and hold it for 2 hours; S22: The heated and heat-preserved slab is rolled in 10 passes, with the cumulative reduction rate of the last three passes not less than 40%, and the final rolling temperature controlled at 880℃. S23: The strip after final rolling is immediately subjected to laminar flow cooling, and the strip is cooled to 600°C at a cooling rate of 25°C / s to obtain hot-rolled strip with phase transformation structure.

[0027] S3 specifically includes: S31: The strip head is fed into the coiler and wound into a coil under tension control to obtain a hot-rolled coil; S32: The hot-rolled coil is placed in air and subjected to self-tempering using residual heat.

[0028] S4 specifically includes: S41: After the hot-rolled coil is uncoiled, it is guided through a hydrochloric acid pickling tank with a hydrochloric acid concentration of 15wt%, a pickling temperature of 80℃, and a pickling time of 120 seconds to remove the iron oxide scale on the surface of the hot-rolled coil. S42: After pickling, cleaning, and drying, the strip steel is subjected to multiple cold rolling passes with a total reduction rate of 60% to obtain a cold-rolled steel strip with a thickness of 0.8 mm.

[0029] S5 specifically includes: S51: Uncoil the cold-rolled steel strip and straighten it using a straightening machine to eliminate poor strip shape; S52: The straightened steel strip is continuously fed into a cold bending forming unit consisting of 16 forming rollers. The profile of each forming roller changes sequentially, so that the steel strip is gradually bent at room temperature to form a continuous profile with a predetermined cross-sectional shape. S53: Using a flying saw, the continuous profile is dynamically cut to a set length to obtain a semi-finished keel.

[0030] S6 specifically includes: S61: Place the semi-finished keel in a stretching machine and apply 1.2% tensile plastic strain along its longitudinal direction; S62: Place the pre-strained keel semi-finished product in a continuous aging furnace and hold it at 340℃ for 60 minutes, then air cool it to room temperature.

[0031] S7 specifically includes: S71: The semi-finished keel after S6 treatment is degreased, washed with water, acid-washed and activated, and then washed and dried with water. The acid-washed and activated solution is a 10wt% sulfuric acid solution, and the treatment time is 60 seconds. S72: The pre-treated keel semi-finished product is immersed in a zinc-aluminum-magnesium alloy molten plating solution at 460℃ for 8 seconds. After being taken out, the coating thickness is controlled by an air knife and cooled to form a metal coating with a unit area weight of 180g / m². S73: Coat the keel with a metal coating with a chromium-free passivating agent with a thickness of 3μm; S74: The coated keel is cut to length, straightened by pressure using a straightening machine to control straightness, inspected and packaged to obtain a high-strength, deformation-resistant light steel keel finished product.

[0032] Example 2 S1: The following raw materials are proportioned by mass: C 0.05%, Si 0.1%, Mn 0.8%, P 0.025%, S 0.020%, Nb 0.015%, V 0.03%, Ti 0.01%, Cu 0.2%, Cr 0.15%, Al 0.015%, N 0.007%, Mo 0.05%, Ni 0.10%, with the balance being Fe. All components are placed in an electric furnace and heated to melt, with the tapping temperature controlled at 1620℃. The molten steel is then transferred to an LF refining furnace for deoxidation and desulfurization under an argon protective atmosphere for 25 minutes. Next, the molten steel is transferred to an RH vacuum circulation degassing unit and treated under a vacuum of 50 Pa for 15 minutes. After refining, the molten steel is injected into the crystallizer for continuous casting. The casting speed is set to 1.2 m / min, and the cooling water flow rate of the crystallizer is 120 m³ / h. Finally, a slab with a thickness of 150 mm is obtained. S2: The slab is fed into a heating furnace, heated to 1180℃ and held for 1 hour to ensure uniform internal temperature. Immediately after exiting the furnace, it undergoes nine passes of hot continuous rolling deformation processing. During rolling, the cumulative reduction rate of the last three passes is controlled to be no less than 40%, and the final rolling temperature is controlled at 860℃. Immediately after final rolling, laminar flow cooling is performed, cooling the strip to 550℃ at a rate of 15℃ / s to form a hot-rolled strip with a phase transformation structure. S3: The head of the hot-rolled strip is fed into the coiler and coiled under tension control to obtain a tightly formed hot-rolled coil. After coiling, the hot-rolled coil is placed in the air and subjected to self-tempering treatment by its own residual heat to further stabilize the structure and improve the initial strength. S4: The hot-rolled coil is uncoiled and guided through a hydrochloric acid pickling tank to remove iron oxide scale. The concentration of hydrochloric acid used is 12wt%, the pickling temperature is 70℃, and the pickling time is 90 seconds. After pickling, it is cleaned and dried, and then sent to a multi-pass cold rolling mill for pressing deformation. The total reduction rate is controlled at 50%, and finally the strip thickness is pressed to 0.4mm to obtain high-precision cold-rolled steel strip. S5: The cold-rolled steel strip is uncoiled and straightened for flatness defects by a straightening machine. It is then continuously fed into a cold bending forming unit consisting of 12 forming rollers. The profile of each forming roller gradually changes, allowing the steel strip to be continuously cold-bent at room temperature to form a continuous profile with a U-shaped cross-section. A hydraulic punching and shearing machine is used to dynamically cut the profile to a set length of 3 meters to obtain the keel semi-finished product. S6: Place the semi-finished keel in a stretching machine and apply 0.8% plastic pre-strain along the longitudinal direction. After completion, send it into a continuous aging furnace and keep it at 300°C for 45 minutes. Then, cool it to room temperature by air cooling to promote the formation of strengthening precipitates of microalloying elements such as Nb, V, and Ti, thereby improving the yield strength of the material. S7: The semi-finished keel product after aging treatment is sequentially degreased, washed with water, acid-washed for activation, and dried. The acid-washing activation solution is an 8wt% sulfuric acid solution, and the treatment time is 30 seconds. Then, the semi-finished keel product is immersed in a 450℃ zinc-aluminum-magnesium alloy molten plating bath for metal plating treatment, with an immersion time of 3 seconds, controlling the formation of a plating layer with a unit area weight of 120g / m². After removal, a 1μm thick layer of water-based acrylic resin sealant is applied. Finally, the product undergoes length-cutting, straightening, shaping, and packaging processes to obtain a high-strength, deformation-resistant light steel keel product.

[0033] Example 3 S1: The following raw materials are proportioned by mass: C 0.15%, Si 0.35%, Mn 1.60%, P 0.025%, S 0.020%, Nb 0.045%, V 0.08%, Ti 0.04%, Cu 0.50%, Cr 0.40%, Al 0.050%, N 0.007%, Mo 0.20%, Ni 0.30%, with the balance being Fe. All components are placed in an electric furnace and heated to melt, with the tapping temperature controlled at 1660℃. The molten steel is then transferred to an LF refining furnace for deoxidation and desulfurization under an argon protective atmosphere for 45 minutes. Next, the molten steel is transferred to an RH vacuum circulation degassing unit and treated under a vacuum of 100 Pa for 25 minutes. After refining, the molten steel is injected into the crystallizer for continuous casting. The casting speed is set to 1.6 m / min, and the cooling water flow rate of the crystallizer is 180 m³ / h. Finally, a slab with a thickness of 220 mm is obtained. S2: The slab is fed into a heating furnace, heated to 1250℃ and held for 3 hours to ensure uniform internal temperature. Immediately after exiting the furnace, it undergoes 12 passes of hot continuous rolling deformation processing. During rolling, the cumulative reduction rate of the last three passes is controlled to be no less than 40%, and the final rolling temperature is controlled at 920℃. Immediately after final rolling, laminar flow cooling is performed, cooling the strip to 650℃ at a rate of 40℃ / s to form a hot-rolled strip with a phase transformation structure. S3: The head of the hot-rolled strip is fed into the coiler and coiled under tension control to obtain a tightly formed hot-rolled coil. After coiling, the hot-rolled coil is placed in the air and subjected to self-tempering treatment by its own residual heat to further stabilize the structure and improve the initial strength. S4: The hot-rolled coil is uncoiled and guided through a hydrochloric acid pickling tank to remove iron oxide scale. The concentration of hydrochloric acid used is 18wt%, the pickling temperature is 85℃, and the pickling time is 180 seconds. After pickling, it is cleaned and dried, and then sent to a multi-pass cold rolling mill for pressing deformation. The total reduction rate is controlled at 70%, and finally the strip thickness is pressed to 1.2mm to obtain high-precision cold-rolled steel strip. S5: The cold-rolled steel strip is uncoiled and straightened for flatness defects by a straightening machine. It is then continuously fed into a cold bending forming unit consisting of 20 forming rollers. The profile of each forming roller gradually changes, allowing the steel strip to be continuously cold-bent at room temperature to form a continuous profile with an L-shaped cross-section. A flying saw is used to dynamically cut the profile to a set length of 3 meters to obtain the keel semi-finished product. S6: Place the semi-finished keel in a stretching machine and apply 1.5% plastic pre-strain along the longitudinal direction. After completion, send it into a continuous aging furnace and keep it at 380°C for 90 minutes. Then, cool it to room temperature by air cooling to promote the formation of strengthening precipitates of microalloying elements such as Nb, V, and Ti, thereby improving the yield strength of the material. S7: The semi-finished keel product after aging treatment is sequentially degreased, washed with water, acid-washed for activation, and dried. The acid-washing activation solution is a 12wt% sulfuric acid solution, and the treatment time is 90 seconds. Then, the semi-finished keel product is immersed in a 470℃ zinc-aluminum-magnesium alloy molten plating bath for metal plating treatment, with an immersion time of 10 seconds, controlling the formation of a coating with a unit area weight of 275g / m². After removal, a 5μm thick layer of chromium-free passivating agent is applied. Finally, the product undergoes length-cutting, straightening, shaping, and packaging processes to obtain a high-strength, deformation-resistant light steel keel product.

[0034] Comparative Example 1 Raw material ratio: C 0.05%, Si 0.10%, Mn 0.50%, P ≤0.035%, S ≤0.035%, and balance Fe; The preparation steps are as follows: Step 1: Directly purchase conventional low-carbon steel continuous casting billets with a thickness of approximately 180mm, such as Q195 or Q235; heat them to 1150℃, hold them at that temperature for about 1 hour, and then perform 5 simplified hot rolling passes, with the final rolling temperature controlled within the range of 800-850℃, to form hot-rolled strip steel with a thickness of approximately 2.0mm. Step 2: After pickling, the hot-rolled strip steel is rolled down using a single-pass cold rolling mill with a total reduction rate controlled at 35% and a target thickness of 1.0 mm. Then, it is cold-bent at room temperature using 5-8 ordinary forming rolls to form a U-shaped or C-shaped keel with a fixed length of 3 meters. Step 3: Perform conventional hot-dip galvanizing on the formed keel. The galvanizing bath temperature is controlled at 450℃, and the immersion time is 3-5 seconds. The zinc layer weight per unit area is about 60-90g / m². Then, air-cool and solidify, and package directly for shipment.

[0035] Table 1 Comparison of Finished Product Performance Parameters Serial Number Performance indicators Example 1 Example 2 Example 3 Comparative Example 1 1 Tensile strength Rm (MPa) 710 620 765 350 2 Yield strength Rp0.2 (MPa) 585 510 635 260 3 Elongation after fracture A (%) 15.8 14.2 13.5 8.5 4 Cross-sectional dimensional stability deviation (mm / m) ±0.8 ±1.2 ±0.7 ±2.5 5 Weight per unit area of ​​the finished coating (g / m²) 180 120 275 60 6 Corrosion resistance time in neutral salt spray test (h) ≥360 ≥240 ≥480 ≤96 As shown in Table 1 above, Example 1 achieves a stable match between tensile strength, yield strength, and elongation after fracture, ensuring load-bearing capacity while avoiding the plasticity reduction problem caused by high-strength solutions. Its overall mechanical properties are superior to Example 2, and its overall usability is better than Example 3. The cross-sectional dimensional stability deviation of Example 1 is controlled within ±0.8 mm / m, significantly better than Example 2 and Comparative Example 1, indicating that it effectively reduces deformation accumulation after cold bending through the coordinated control of hot rolling, cold rolling, cold bending, pre-straining, and aging. Although Example 3 has a higher coating weight and longer salt spray time, Example 1 achieves a corrosion resistance level of ≥360h under a coating condition of 180 g / m², achieving a better balance between protective performance and material and process costs. Comparative Example 1, due to the use of low-alloy or non-alloy steel and simplified rolling and forming processes, has significantly lower tensile strength, yield strength, and corrosion resistance, failing to meet the requirements of high-strength and deformation-resistant applications. In summary, Example 1 achieves the optimal configuration in terms of strength, plasticity, forming stability, and corrosion resistance, making it the best implementation of this invention.

[0036] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0037] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-strength, deformation-resistant light steel keel, characterized in that, It is made from the following raw materials by weight percentage: C 0.05-0.15%, Si 0.10-0.35%, Mn 0.80-1.60%, P 0.025%, S 0.020%, Nb 0.015-0.045%, V 0.03-0.08%, Ti 0.01-0.04%, Cu 0.20-0.50%, Cr 0.15-0.40%, Al 0.015-0.050%, N 0.007%, Mo 0.05-0.20%, Ni 0.10-0.30%, with the balance being Fe.

2. The high-strength, deformation-resistant light steel keel according to claim 1, characterized in that, The cross-section of the light steel keel is C-shaped, U-shaped or L-shaped, and its web or flange is provided with regularly distributed reinforcing ribs, concave and convex patterns or weight-reducing holes.

3. A method for preparing a high-strength, deformation-resistant light steel keel, used to prepare the high-strength, deformation-resistant light steel keel according to any one of claims 1-2, characterized in that, Includes the following steps: S1: The raw materials are batched according to the proportions described in claim 1, smelted in an electric furnace, and continuously cast to obtain a slab; S2: The slab is heated, kept at a constant temperature and hot rolled in multiple passes, followed by online accelerated cooling to obtain hot-rolled strip steel; S3: The hot-rolled strip steel cooled in S2 is coiled to obtain a hot-rolled coil; S4: Pickling is performed on the hot-rolled coil to remove iron oxide scale, and then cold rolling is performed to the target thickness to obtain cold-rolled steel strip; S5: The cold-rolled steel strip is continuously cold-bent to form a keel semi-finished product with a predetermined cross-sectional shape; S6: Apply pre-strain to the semi-finished keel and then perform low-temperature aging treatment to promote the formation of strengthening precipitates by micro-alloying elements and alloying elements in the raw materials; S7: The semi-finished keel after S6 aging treatment is surface coated and then finished to obtain a high-strength, deformation-resistant light steel keel finished product.

4. The method for preparing a high-strength, deformation-resistant light steel keel according to claim 3, characterized in that, S1 specifically includes: S11: Weigh each component according to the preset raw material ratio and place it in the electric furnace; S12: Smelting is carried out in an electric furnace, and the tapping temperature is controlled at 1620-1660℃; S13: Transfer the molten steel to the LF refining furnace for deoxidation and desulfurization under argon protection. The refining time is 25-45 minutes. S14: Transfer the refined molten steel into the RH vacuum circulation degassing device, control the vacuum degree to 50-100Pa, and the processing time is 15-25 minutes. S15: The treated molten steel is injected into the crystallizer for continuous casting, with the casting speed controlled at 1.2-1.6 m / min and the cooling water flow rate of the crystallizer at 120-180 m³ / h, to obtain a slab with a thickness of 150-220 mm.

5. The method for preparing a high-strength, deformation-resistant light steel keel according to claim 3, characterized in that, S2 specifically includes: S21: The slab is fed into a heating furnace, heated to 1180-1250℃, and held at that temperature for 1-3 hours; S22: The heated and heat-preserved slab is rolled in 9-12 passes, with the cumulative reduction rate of the last three passes not less than 40%, and the final rolling temperature controlled at 860-920℃. S23: The strip steel after final rolling is immediately subjected to laminar flow cooling, and the strip steel is cooled to 550-650℃ at a cooling rate of 15-40℃ / s to obtain hot-rolled strip steel with phase transformation structure.

6. The method for preparing a high-strength, deformation-resistant light steel keel according to claim 3, characterized in that, S3 specifically includes: S31: The strip head is fed into the coiler and wound into a coil under tension control to obtain a hot-rolled coil; S32: The hot-rolled coil is placed in air and subjected to self-tempering using residual heat.

7. The method for preparing a high-strength, deformation-resistant light steel keel according to claim 3, characterized in that, S4 specifically includes: S41: After the hot-rolled coil is uncoiled, it is guided through a hydrochloric acid pickling tank. The concentration of the hydrochloric acid is 12-18 wt%, the pickling temperature is 70-85℃, and the pickling time is 90-180 seconds, in order to remove the iron oxide scale on the surface of the hot-rolled coil. S42: After pickling, cleaning, and drying, the strip steel is subjected to multiple cold rolling passes with a total reduction rate of 50%-70% to obtain a cold-rolled steel strip with a thickness of 0.4-1.2mm.

8. The method for preparing a high-strength, deformation-resistant light steel keel according to claim 3, characterized in that, S5 specifically includes: S51: Uncoil the cold-rolled steel strip and straighten it using a straightening machine to eliminate poor strip shape; S52: The straightened steel strip is continuously fed into a cold bending forming unit consisting of 12-20 forming rollers. The profile of each forming roller changes sequentially, so that the steel strip is gradually bent at room temperature to form a continuous profile with a predetermined cross-sectional shape. S53: Using a flying saw or hydraulic punching and shearing machine, the continuous profile is dynamically cut to a set length to obtain the semi-finished keel.

9. The method for preparing a high-strength, deformation-resistant light steel keel according to claim 3, characterized in that, S6 specifically includes: S61: Place the semi-finished keel in a stretching machine and apply 0.8%-1.5% tensile plastic strain along its longitudinal direction; S62: Place the pre-strained keel semi-finished product in a continuous aging furnace and hold it at 300-380℃ for 45-90 minutes, then air cool to room temperature.

10. The method for preparing a high-strength, deformation-resistant light steel keel according to claim 3, characterized in that, Specifically, S7 includes: S71: The semi-finished keel after S6 treatment is degreased, washed with water, acid-washed and activated, and then washed and dried with water. The acid-washed and activated solution is a sulfuric acid solution with a concentration of 8-12wt%, and the treatment time is 30-90 seconds. S72: The pre-treated keel semi-finished product is immersed in a zinc-aluminum-magnesium alloy molten plating solution at 450-470℃ for 3-10 seconds. After being taken out, the coating thickness is controlled by an air knife and cooled to form a metal coating with a unit area weight of 120-275g / m². S73: Coat the keel with a metal plating with a chromium-free passivating agent or a water-based acrylic resin sealant with a thickness of 1-5 μm. S74: The coated keel is cut to length, straightened by pressure using a straightening machine to control straightness, inspected and packaged to obtain the finished high-strength, deformation-resistant light steel keel.

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