A 600MPa low-cost cold-rolled aluminum-silicon steel sheet and its preparation method

Abstract

The invention discloses a 600MPa-grade low-cost cold-rolled aluminum-silicon steel plate and a preparation method thereof, wherein the steel plate composition and its weight percentage are: C 0.07-0.15%; Mn 1.0-2.5%; S≤0.010%; P≤0.020%; Si 0.10-0.70%; Als≥0.025%; the rest is Fe and inclusions within the allowable range; the preparation method comprises a hot rolling process, a cold rolling process and an aluminum-silicon plating process, wherein the aluminum-silicon plating process: the steel plate is heated to 750°C-860°C in a continuous hot-dip aluminum production line, the insulation temperature is 750°C-860°C, cooled to 660°C-700°C and enters the aluminum-silicon plating solution, and after exiting the plating solution, it is rapidly cooled to below 260°C at a speed greater than 20°C / s. The steel plate prepared by the present invention has a strength of more than 600MPa, a high elongation and good formability.

Description

Technical Field

[0001] The invention relates to a cold-rolled aluminum-silicon coated product and a preparation method thereof, in particular to a 600MPa-grade low-cost cold-rolled aluminum-silicon coated steel sheet and a preparation method thereof. Background Art

[0002] Aluminum-silicon coating has good heat resistance and oxidation resistance as well as excellent corrosion resistance and heat reflectivity. The product is mainly used for household appliances and automotive products with high temperature resistance and strict corrosion resistance requirements.

[0003] Aluminum-silicon coated products have excellent corrosion resistance. The dense Al2O3 oxide film formed by the oxidation of the aluminum surface isolates the steel base from the oxidizing medium, so that the coating will not cause further corrosion even under very harsh environmental conditions. Therefore, it has a strong anti-corrosion effect and has good corrosion resistance to nitric acid, seawater, etc. The corrosion resistance of aluminum-silicon coated products is much greater than that of galvanized products.

[0004] Aluminum-silicon coated products have good high temperature resistance. When the temperature is 450℃, it can ensure extremely high reflectivity. It hardly changes in long-term use below 550℃. The aluminum-silicon coated steel plate will maintain a bright appearance. Its heat resistance is equivalent to that of stainless steel 409.

[0005] Aluminum-coated silicon has excellent thermal reflectivity. At temperatures below 500°C, it has a light reflectivity of about 80%, and a reflectivity of 95% under infrared light. Therefore, aluminum-coated silicon products can be used as efficient thermal insulation barriers or heat reflectors in high-temperature applications, rapidly raising the temperature in the furnace through effective heat reflection.

[0006] "Lightweighting" is becoming more and more important in the automotive industry because it can directly reduce fuel consumption and emissions. Data show that for every 1% reduction, fuel consumption can be reduced by 0.6%-1.0%. Energy consumption is closely related to exhaust emissions. Therefore, lightweighting of automobiles has great practical significance for energy saving and environmental protection. Dual-phase steel is suitable for manufacturing structural parts and reinforcement parts due to its good strength and deep drawing performance, excellent fatigue performance, energy absorption and other characteristics. At present, with the increasing requirements for safety, the proportion of dual-phase steel used in automobiles is increasing. Cold-rolled aluminum-silicon steel sheets have good corrosion resistance and high temperature resistance, which conforms to the parts in the automobile body that have high requirements for heat resistance and corrosion resistance.

[0007] Existing aluminum-plated products mainly include cold-stamped steel plates and hot-pressed steel plates, which have low strength levels and result in low steel utilization efficiency. This patent provides a 600MPa-grade low-cost cold-rolled aluminum-silicon steel plate and a preparation method thereof, which can produce 600MPa-grade hot-dip aluminum-silicon steel plates, improve resource utilization efficiency, reduce energy consumption, and achieve sustainable development. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet.

[0009] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0010] A 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet, the composition and its weight percentage are: C 0.07-0.15%; Mn 1.0-2.5%; S≤0.010%; P≤0.020%; Si 0.10-0.70%; Als≥0.025%; the rest is Fe and inclusions within the allowable range.

[0011] The steel plate of the present invention has a microstructure of ferrite+martensite+retained austenite, wherein the volume fractions thereof are 70% to 90% ferrite, 9% to 25% martensite, and 1% to 5% retained austenite.

[0012] The present invention also provides a method for preparing a 600MPa-grade low-cost cold-rolled aluminum-silicon-coated steel sheet with low cost and simple operation.

[0013] The production method of the 600MPa-level low-cost cold-rolled aluminum-silicon-plated steel plate of the present invention comprises a hot rolling process, a cold rolling process and a galvanizing process.

[0014] The hot rolling process of the method of the present invention comprises the following steps: heating temperature is 1000-1150°C, heat preservation is performed for 1-2 hours, final rolling temperature is 850-900°C, front-stage cooling is adopted in cooling mode, and coiling temperature is 620-680°C.

[0015] The cold rolling reduction ratio in the cold rolling process of the method of the present invention is 45% to 76%.

[0016] The galvanizing process of the method of the present invention is as follows: the steel plate is heated to 750°C-860°C in a continuous hot-dip aluminum production line, kept at a temperature of 750°C-860°C, cooled to 660°C-700°C and enters the aluminum-silicon plating solution, and after exiting the plating solution, is rapidly cooled to below 260°C at a speed greater than 20°C / s.

[0017] In the galvanizing process of the method of the present invention, the total elongation of the skin pass machine and the straightening machine is controlled within the range of 0.5-1.2%.

[0018] The inventive principle of the present invention is:

[0019] The present invention improves the hardenability of steel, reduces the Ac3 line, and shifts the CCT curve of steel to the right by increasing the carbon and silicon contents, thereby ensuring that the proportion of martensite in the aluminum-silicon plated product is above 9%.

[0020] The present invention ensures a sufficient austenite ratio by controlling the temperature and soaking time of the dual-phase zone in the aluminum silicon plating process; at the same time, by controlling the temperature before entering the aluminum silicon plating, it is ensured that the austenite will not be converted into bainite, and the plating performance of the aluminum silicon plating is ensured. By adopting the cooling rate before entering the zinc pot, while ensuring a sufficient martensite ratio and the yield strength ratio of the product, the strength meets the standard requirements.

[0021] The beneficial effects of the technical solution of the present invention are:

[0022] The present invention does not use precious alloy elements such as molybdenum, titanium and chromium. By appropriately increasing the carbon and silicon contents and adding appropriate manganese elements, the hardenability of the steel can be improved, which not only ensures the castability of the product, the stability of product production and the stability of product performance, but also reduces the production cost.

[0023] The present invention produces hot-rolled raw materials suitable for cold rolling requirements by reasonably controlling the smelting and hot-rolling processes; solves the rolling difficulty problem by reasonably controlling the compression ratio in cold rolling; and overcomes the problem of insufficient martensite proportion in the production process by reasonably controlling the cooling rate after plating. Therefore, the method of the present invention not only ensures the convenience of hot-rolling production, easy control of cold-rolling processing and galvanizing processes, but also ensures the performance hit rate of the product and the processing and use performance of the product, and can effectively reduce the production cost.

[0024] The steel plate prepared by the invention has a tensile strength of not less than 600 MPa, a yield strength of 360-430 MPa, an A80 of not less than 25.5%, and a BH of 40-55. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the metallographic structure of the steel plate in Example 4. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below in conjunction with specific embodiments. Example 1

[0027] The composition and weight percentage of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment are: C 0.076%, Mn 1.25%, S 0.003%, P 0.017%, Si 0.25%, Als 0.032%, and the balance is iron and inclusions within the allowable range.

[0028] The preparation method of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment is as follows:

[0029] (1) Hot rolling: The ingot is rolled into hot-rolled strip by a conventional hot rolling production line. The hot-rolled strip has a rolling specification of 5.0×1240 mm. The main process parameters of the hot rolling process are: ingot heating temperature of 1030°C, soaking time of 1.5 hours, final rolling temperature of 870°C, front-end cooling, and coiling temperature of 632°C.

[0030] The properties of hot-rolled products are: tensile strength 475MPa, yield strength 358MPa, and elongation 31.5%.

[0031] (2) Cold rolling: The cold rolling thickness is 2.0×1219mm and the compression ratio is 60%.

[0032] (3) Aluminum-silicon plating: A conventional aluminum-silicon plating production line is used for aluminum-silicon plating. The main process parameters of the aluminum-silicon plating process are: production line speed of 70m / min, strip heating temperature of 781℃, strip uniform temperature of 778℃, strip uniform time of 54.5s, strip cooled to 665℃ and entered into the aluminum-silicon plating solution, and then rapidly cooled to 255℃ at a rate of 21.3℃ / s after exiting the plating solution; the total elongation of skin-smoothing and straightening is 0.54%; other parameters are the same as the operating parameters of ordinary aluminum-silicon plating products.

[0033] The properties of the aluminum-silicon coated steel sheet prepared in this embodiment are: tensile strength 620 MPa, yield strength 368 MPa, A80=28%, BH=46; the metallographic structure of the steel sheet in this embodiment is: ferrite 72%, martensite 25%, and retained austenite 3%. Example 2

[0034] The composition and weight percentage of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment are: C 0.096%, Mn 1.45%, S 0.005%, P 0.015%, Si 0.39%, Als 0.041%, and the balance is iron and inclusions within the allowable range.

[0035] The preparation method of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment is as follows:

[0036] (1) Hot rolling: The ingot is rolled into hot-rolled strip by a conventional hot rolling production line. The hot-rolled strip has a rolling specification of 5.0×1270 mm. The main process parameters of the hot rolling process are: ingot heating temperature of 1060°C, soaking time of 2 hours, final rolling temperature of 880°C, front-end cooling for cooling, and coiling temperature of 645°C.

[0037] The properties of hot-rolled products are: tensile strength 504MPa, yield strength 394MPa, and elongation 27.5%.

[0038] (2) Cold rolling: The cold rolling thickness is 1.5×1250mm and the compression ratio is 62.5%.

[0039] (3) Aluminum-silicon plating: A conventional aluminum-silicon plating production line is used for aluminum-silicon plating. The main process parameters of the aluminum-silicon plating process are: production line speed is 90m / min, strip heating temperature is 795℃, strip uniform temperature is 792℃, strip uniform time is 42.4s, strip is cooled to 670℃ and enters the aluminum-silicon plating solution, and is rapidly cooled to 250℃ at a rate of 27.4℃ / s after exiting the plating solution; the total elongation of the skin straightening and straightening is 0.65%; other parameters are the same as the operating parameters of ordinary aluminum-silicon plating products.

[0040] The properties of the aluminum-silicon coated steel sheet prepared in this embodiment are: tensile strength 639 MPa, yield strength 375 MPa, A80=31%, BH=55; the metallographic structure of the steel sheet in this embodiment is: ferrite 77%, martensite 21%, and retained austenite 2%. Example 3

[0041] The composition and weight percentage of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment are: C 0.121%, Mn 1.55%, S 0.004%, P 0.014%, Si 0.52%, Als 0.042%, and the balance is iron and inclusions within the allowable range.

[0042] The preparation method of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment is as follows:

[0043] (1) Hot rolling: The ingot is rolled into hot-rolled strip by a conventional hot rolling production line. The hot-rolled strip has a rolling specification of 3.0×1270 mm. The main process parameters of the hot rolling process are: ingot heating temperature of 1080°C, soaking time of 2 hours, final rolling temperature of 880°C, front-end cooling for cooling, and coiling temperature of 650°C.

[0044] The properties of hot-rolled products are: tensile strength 524MPa, yield strength 416MPa, and elongation 26.5%.

[0045] (2) Cold rolling: The cold rolling thickness is 1.2×1250mm and the compression ratio is 60.0%.

[0046] (3) Aluminum-silicon plating: A conventional aluminum-silicon plating production line is used for aluminum-silicon plating. The main process parameters of the aluminum-silicon plating process are: production line speed of 100m / min, strip heating temperature of 800℃, strip uniform temperature of 803℃, strip uniform time of 38.16s, cooled to 675℃ and entered into the aluminum-silicon plating solution, and then rapidly cooled to 250℃ at a speed of 30.4℃ / s after exiting the plating solution; the total elongation of skin straightening and straightening is 0.8%; other parameters are the same as the operating parameters of ordinary aluminum-silicon plating products.

[0047] The properties of the aluminum-silicon coated steel sheet prepared in this embodiment are: tensile strength 642MPa, yield strength 385MPa, A80=27%, BH=48; the metallographic structure of the steel sheet in this embodiment is: ferrite 80%, martensite 17%, and retained austenite 3%. Example 4

[0048] The composition and weight percentage of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment are: C 0.13%, Mn 1.83%, S 0.004%, P 0.014%, Si 0.55%, Als 0.045%, and the balance is iron and inclusions within the allowable range.

[0049] The preparation method of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment is as follows:

[0050] (1) Hot rolling: The ingot is rolled into hot-rolled strip by a conventional hot rolling production line. The hot-rolled strip has a rolling specification of 2.75×1270 mm. The main process parameters of the hot rolling process are: ingot heating temperature 1010°C, soaking time 2 hours, final rolling temperature 885°C, front-end cooling, and coiling temperature 6+0°C.

[0051] The properties of hot-rolled products are: tensile strength 534MPa, yield strength 420MPa, and elongation 26.0%.

[0052] (2) Cold rolling: The cold rolling thickness is 1.0×1250mm and the compression ratio is 63.6%.

[0053] (3) Aluminum-silicon plating: A conventional aluminum-silicon plating production line is used for aluminum-silicon plating. The main process parameters of the aluminum-silicon plating process are: production line speed is 110m / min, strip heating temperature is 815℃, strip uniform temperature is 818℃, strip uniform time is 34.69s, strip is cooled to 685℃ and enters the aluminum-silicon plating solution, and then is rapidly cooled to 250℃ at a speed of 33.4℃ / s after exiting the plating solution; the total elongation of skin straightening and straightening is 0.85%; other parameters are the same as the operating parameters of ordinary aluminum-silicon plating products.

[0054] The properties of the aluminum-silicon plate prepared in this embodiment are: tensile strength 650MPa, yield strength 392MPa, A80=27.5%, BH=53; the metallographic structure of the steel plate in this embodiment is shown in Figure 1 , its composition is: ferrite 85%, martensite 14%, retained austenite 1%. Example 5

[0055] The composition and weight percentage of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment are: C 0.141%, Mn 2.15%, S 0.006%, P 0.013%, Si 0.62%, Als 0.045%, and the balance is iron and inclusions within the allowable range.

[0056] The preparation method of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment is as follows:

[0057] (1) Hot rolling: The ingot is rolled into hot-rolled strip by a conventional hot rolling production line. The hot-rolled strip has a rolling specification of 2.5×1270 mm. The main process parameters of the hot rolling process are: ingot heating temperature of 1120°C, soaking time of 2 hours, final rolling temperature of 895°C, front-end cooling for cooling, and coiling temperature of 675°C.

[0058] The properties of hot-rolled products are: tensile strength 554MPa, yield strength 408MPa, and elongation 25.5%.

[0059] (2) Cold rolling: The cold rolling thickness is 0.9×1250mm and the compression ratio is 64.0%.

[0060] (3) Aluminum-silicon plating: A conventional aluminum-silicon plating production line is used for aluminum-silicon plating. The main process parameters of the aluminum-silicon plating process are: production line speed is 120m / min, strip heating temperature is 823℃, strip uniform temperature is 825℃, strip uniform time is 34.98s, strip is cooled to 690℃ and enters the aluminum-silicon plating solution, and then is rapidly cooled to 250℃ at a speed of 36.48℃ / s after exiting the plating solution; the total elongation of skin-smoothing and straightening is 1.2%; other parameters are the same as the operating parameters of ordinary aluminum-silicon plating products.

[0061] The properties of the aluminum-silicon coated steel sheet prepared in this embodiment are: tensile strength 653 MPa, yield strength 401 MPa, A80=25.5%, BH=40; the metallographic structure of the steel sheet in this embodiment is: ferrite 87%, martensite 10%, and retained austenite 3%. Example 6

[0062] The composition and weight percentage of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment are: C 0.15%, Mn 2.49%, S 0.010%, P 0.018%, Si 0.70%, Als 0.028%, and the balance is iron and inclusions within the allowable range.

[0063] The preparation method of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment is as follows:

[0064] (1) Hot rolling: The ingot is rolled into hot-rolled strip by a conventional hot rolling production line. The hot-rolled strip has a rolling specification of 2.5×1220 mm. The main process parameters of the hot rolling process are: ingot heating temperature of 1150°C, soaking time of 1.5 hours, final rolling temperature of 900°C, front-end cooling for cooling, and coiling temperature of 680°C.

[0065] The properties of hot-rolled products are: tensile strength 563MPa, yield strength 451MPa, and elongation 22.5%.

[0066] (2) Cold rolling: The cold rolling thickness is 0.6×1200mm and the compression ratio is 76.0%.

[0067] (3) Aluminum-silicon plating: A conventional aluminum-silicon plating production line is used for aluminum-silicon plating. The main process parameters of the aluminum-silicon plating process are: production line speed of 140m / min, strip heating temperature of 845℃, strip uniform temperature of 848℃, strip uniform time of 27.21s, cooled to 700℃ and entered into the aluminum-silicon plating solution, and then rapidly cooled to 240℃ at a speed of 44.41℃ / s after exiting the plating solution; the total elongation of skin-smoothing and straightening is 1.52%; other parameters are the same as the operating parameters of ordinary aluminum-silicon plating products.

[0068] The properties of the aluminum-silicon coated steel sheet prepared in this embodiment are as follows: tensile strength 682 MPa, yield strength 430 MPa, A80=25.0%, BH=52; ferrite 90%, martensite 9%, and retained austenite 1%. Example 7

[0069] The composition and weight percentage of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment are: C 0.113%, Mn 2.31%, S 0.008%, P 0.020%, Si 0.44%, Als 0.025%, and the balance is iron and inclusions within the allowable range.

[0070] The preparation method of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment is as follows:

[0071] (1) Hot rolling: The ingot is rolled into hot-rolled strip by a conventional hot rolling production line. The hot-rolled strip has a rolling specification of 5.0×1320 mm. The main process parameters of the hot rolling process are: ingot heating temperature of 1020°C, soaking time of 1 hour, final rolling temperature of 860°C, front-end cooling for cooling, and coiling temperature of 625°C.

[0072] The properties of hot-rolled products are: tensile strength 550 MPa, yield strength 443 MPa, and elongation 23.0%.

[0073] (2) Cold rolling: The cold rolling thickness is 2.5×1300mm and the compression ratio is 50%.

[0074] (3) Aluminum-silicon plating: A conventional aluminum-silicon plating production line is used for aluminum-silicon plating. The main process parameters of the aluminum-silicon plating process are: production line speed is 65m / min, strip heating temperature is 860℃, strip uniform temperature is 860℃, strip uniform time is 58.62s, strip is cooled to 680℃ and enters the aluminum-silicon plating solution, and is rapidly cooled to 240℃ at a rate of 20.46℃ / s after exiting the plating solution; the total elongation of the skin straightening and straightening is 0.49%; other parameters are the same as the operating parameters of ordinary aluminum-silicon plating products.

[0075] The properties of the aluminum-silicon coated steel sheet prepared in this embodiment are: tensile strength 611 MPa, yield strength 372 MPa, A80=32.5%, BH=43; the metallographic structure of the steel sheet in this embodiment is: ferrite 70%, martensite 25%, and retained austenite 5%. Example 8

[0076] The composition and weight percentage of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment are: C 0.07%, Mn 1.02%, S 0.002%, P 0.016%, Si 0.10%, Als 0.036%, and the balance is iron and inclusions within the allowable range.

[0077] The preparation method of the 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet in this embodiment is as follows:

[0078] (1) Hot rolling: The ingot is rolled into hot-rolled strip by a conventional hot rolling production line. The hot-rolled strip has a rolling specification of 5.0×1350 mm. The main process parameters of the hot rolling process are: ingot heating temperature of 1000°C, soaking time of 1 hour, final rolling temperature of 850°C, front-end cooling for cooling, and coiling temperature of 620°C.

[0079] The properties of hot-rolled products are: tensile strength 468MPa, yield strength 355MPa, and elongation 32.0%.

[0080] (2) Cold rolling: The cold rolling thickness is 2.75×1330mm and the compression ratio is 45.0%.

[0081] (3) Aluminum-silicon plating: A conventional aluminum-silicon plating production line is used for aluminum-silicon plating. The main process parameters of the aluminum-silicon plating process are: production line speed of 60m / min, strip heating temperature of 750℃, strip absorptive temperature of 752℃, strip absorptive time of 63.50s, strip cooling to 660℃ and entering the aluminum-silicon plating solution, and then rapidly cooling to 235℃ at a speed of 18.90℃ / s after exiting the plating solution; the total elongation of skin-smoothing and straightening is 0.41%; other parameters are the same as the operating parameters of ordinary aluminum-silicon plating products.

[0082] The properties of the aluminum-silicon coated steel sheet prepared in this embodiment are: tensile strength 637MPa, yield strength 397MPa, A80=31.5%, BH=51; the metallographic structure of the steel sheet in this embodiment is: ferrite 75%, martensite 10%, and retained austenite 5%.

Claims

1. A 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet, characterized in that: The steel plate components and their weight percentages are: C 0.07-0.15%; Mn 1.0-2.5%; S≤0.010%; P≤0.020%; Si 0.10-0.70%; Als ≥ 0.025%; the rest is Fe and inclusions within the allowable range; The steel plate structure is composed of ferrite + martensite + retained austenite, with volume fractions of ferrite 70% to 90%, martensite 9% to 25%, and retained austenite 1% to 5% respectively; The steel plate has a tensile strength of not less than 600 MPa, a yield strength of 360-430 MPa, an A80 of not less than 25.5%, and a BH of 40-55; The preparation method of the steel plate includes a hot rolling process, a cold rolling process and an aluminum-silicon plating process; wherein the main process parameters of the aluminum-silicon plating process are: the steel plate is heated to 750°C-860°C in a continuous hot-dip aluminum plating production line, the insulation temperature is 750°C-860°C, cooled to 660°C-700°C and enters the aluminum-silicon plating solution, and after exiting the plating solution, it is rapidly cooled to below 260°C at a speed greater than 20°C / s.

2. The method for preparing a 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet according to claim 1, characterized in that: The preparation method comprises a hot rolling process, a cold rolling process and an aluminum silicon plating process; wherein the main process parameters of the aluminum silicon plating process are: the steel plate is heated to 750°C-860°C in a continuous hot-dip aluminum plating production line, the insulation temperature is 750°C-860°C, cooled to 660°C-700°C and enters the aluminum silicon plating solution, and after exiting the plating solution, it is rapidly cooled to below 260°C at a speed greater than 20°C / s.

3. The method for preparing a 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet according to claim 2, characterized in that: The main process parameters of the hot rolling process are: heating temperature of the ingot is 1000-1150°C, keeping temperature for 1-2 hours, final rolling temperature is 850-900°C, cooling mode adopts front-stage cooling, and coiling temperature is 620-680°C.

4. The method for preparing a 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet according to claim 2, characterized in that: The cold rolling reduction ratio in the cold rolling process is 45% to 76%.

5. The method for preparing a 600MPa grade low-cost cold-rolled aluminum-silicon coated steel sheet according to claim 2, characterized in that: In the aluminum silicon plating process, the total elongation of the skin pass machine and the straightening machine is controlled at 0.4-1.5%.

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