Production method of 6-8mm low-cost high-strength rare earth weathering steel

Abstract

The invention discloses a production method of 6-8mm low-cost high-strength rare earth weathering resistant steel. The production method comprises the following steps: (1) smelting-continuous casting production; wherein the molten steel comprises the following chemical components in percentage by mass: 0.11 to 0.13 percent of C, 0.25 to 0.35 percent of S , 0.5 to 0.6 percent of Mn, 0.06 to 0.08 percent of P, less than or equal to 0.008 percent of S, 0.20 to 0.25 percent of Cu, 2.1 to 2.3 percent of Cr, 0.12 to 0.14 percent of T , 20 to 80 ppm of La / Ce and 0.020 to 0.050 percent of Alt; and (2) a hot rolling production process flow: casting blanks, an induction heating furnace, a laboratory rolling mill, laminar cooling and simulated coiling. A conventional C, S, i and Mn component system design is adopted, and the corrosion resistance of the steel strip is improved by adding corrosion-resistant elements Cu, Cr, P and Ti and a small amount of rare earth La / Ce mixed rare earth.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical plate production, and in particular relates to a production method of 6-8 mm low-cost high-strength rare earth weathering steel. Background Art

[0002] The steel used in photovoltaic brackets is concentrated in the bracket structure. The bracket structure is mainly composed of components such as columns, main beams, purlins, etc. The raw materials are mainly: aluminum alloy, 304 stainless steel, Q235 steel plate + hot-dip galvanized steel parts, galvanized plates, zinc-aluminum-magnesium plates, weather-resistant steel plates, etc. At present, Q235 steel plate + hot-dip galvanized steel parts are the main photovoltaic bracket parts. The production of components is to cold-bending, stamping, sawing, laser cutting, plasma cutting, welding, hot-dip galvanizing and other processing processes on the steel plates, which have high requirements on product processing accuracy, production efficiency and quality consistency.

[0003] Corrosion resistance, high strength and good fatigue performance are the most important requirements for photovoltaic bracket materials. It is necessary to ensure that the steel structure is firm and reliable within 25 years, and can withstand harsh environmental erosion, wind, snow loads and other external effects, and achieve the maximum use effect with the minimum installation cost. In the early stage, galvanized brackets were widely used due to their stable performance, mature manufacturing process, high bearing capacity and easy installation. However, as people's requirements for the cost-effectiveness of photovoltaic projects become higher and higher, photovoltaic brackets are accelerating towards high strength, lightweight and green development. Weathering steel brackets are increasingly favored by large domestic photovoltaic power station projects due to their good corrosion resistance, environmental protection and high cost-effectiveness. Summary of the invention

[0004] The purpose of the present invention is to provide a production method of 6-8mm low-cost high-strength rare earth weathering steel, which adopts a conventional CSiMn component system design and improves the corrosion resistance of the steel strip by adding corrosion-resistant elements Cu, Cr, P, Ti and a small amount of rare earth La / Ce mixed rare earth.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for producing 6-8 mm low-cost high-strength rare earth weathering steel, comprising:

[0007] (1) Smelting-continuous casting production process; the chemical composition of the molten steel by mass percentage is: C: 0.11-0.13%, Si: 0.25-0.35%, Mn: 0.5-0.6%, P: 0.06-0.08%, S: ≤0.008%, Cu: 0.20-0.25%, Cr: 2.1-2.3%, Ti: 0.12-0.14%, La / Ce (mixed rare earth content ratio is 1:1): 20-80ppm, Alt: 0.020-0.050%; the rest is Fe and unavoidable impurities;

[0008] (2) Hot rolling production process: ingot casting - induction heating furnace - laboratory rolling mill - laminar cooling - simulated coiling; ingot furnace temperature is 1250±20℃, the final rolling temperature of finishing rolling is 900℃, the cooling rate is 10-20℃ / S, and the thickness of hot rolled steel strip is 6-8mm; cooling adopts laminar cooling equipment, front dispersed cooling mode, and the coiling temperature is 650±10℃.

[0009] Furthermore, the chemical composition of the weathering steel by mass percentage is: C: 0.12%, Si: 0.27%, Mn: 0.53%, P: 0.072%, S: 0.004%, Cu: 0.22%, Cr: 2.20%, Ti: 0.12%, La / Ce: 50ppm, Alt: 0.030%; the rest is Fe and unavoidable impurities.

[0010] Furthermore, the chemical composition of the weathering steel by mass percentage is: C: 0.12%, Si: 0.27%, Mn: 0.52%, P: 0.070%, S: 0.003%, Cu: 0.21%, Cr: 2.21%, Ti: 0.12%, La / Ce: 44ppm, Alt: 0.031%; the rest is Fe and unavoidable impurities.

[0011] Furthermore, the chemical composition of the weathering steel by mass percentage is: C: 0.12%, Si: 0.25%, Mn: 0.59%, P: 0.073%, S: 0.003%, Cu: 0.25%, Cr: 2.18%, Ti: 0.12%, La / Ce: 53ppm, Alt: 0.030%; the rest is Fe and unavoidable impurities.

[0012] Furthermore, the rolling is carried out using a traditional 2250 hot rolling production line; the slab heating temperature is 1260°C, the heating time is 50 minutes, and the hot rolling mill is used for rolling; the finishing rolling temperature is 897°C, and the finished product thickness is 8mm; the laminar cooling adopts front dispersion cooling, the cooling rate is 20°C / S, and the steel strip temperature is reduced to 656°C for coiling; finally, the product performance is tested.

[0013] Furthermore, the rolling is carried out using a traditional 2250 hot rolling production line; the slab heating temperature is 1250°C, the heating time is 50 minutes, and a hot rolling mill is used for rolling; the finishing rolling temperature is 900°C, and the finished product thickness is 8mm; laminar cooling uses front dispersion cooling, the cooling rate is 18°C / S, and the steel strip temperature is reduced to 659°C for coiling; finally, the product performance is tested.

[0014] Furthermore, the rolling is carried out using a traditional 2250 hot rolling production line; the slab heating temperature is 1243°C, the heating time is 49 minutes, and the hot rolling mill is used for rolling; the finishing rolling temperature is 890°C, and the finished product thickness is 8mm; laminar cooling uses front dispersion cooling, the cooling rate is 19°C / S, and the steel strip temperature is reduced to 643°C for coiling; finally, the product performance is tested.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are:

[0016] The metallographic microstructure of the steel of the present invention is bainite + a small amount of ferrite. A 6-8mm low-cost high-strength rare earth weathering steel produced by the method provided by the present invention has been tested and its mechanical properties and process properties meet relevant standards and user requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Figure 1 This is the microstructure diagram of Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The present invention is described in more detail below through specific examples. The examples are only descriptions of the best mode of implementation of the present invention and do not limit the scope of the present invention in any way.

[0020] Example 1

[0021] The rolling is carried out using a conventional 2250 hot rolling production line. The slab heating temperature is 1260°C, the heating time is 50 minutes, and the hot rolling mill is used for rolling. The finishing rolling temperature is 897°C, and the finished product thickness is 8mm. The laminar cooling adopts front dispersion cooling, the cooling rate is 20°C / S, and the steel strip temperature is reduced to 656°C for coiling. Finally, the product performance test is carried out.

[0022] Example 2

[0023] The rolling is carried out using a conventional 2250 hot rolling production line. The slab heating temperature is 1250°C, the heating time is 50 minutes, and the hot rolling mill is used for rolling. The finishing rolling temperature is 900°C, and the finished product thickness is 8mm. The laminar cooling adopts front dispersion cooling, the cooling rate is 18°C / S, and the steel strip temperature is reduced to 659°C for coiling. Finally, the product performance test is carried out.

[0024] Example 3

[0025] The rolling is carried out using the traditional 2250 hot rolling production line. The slab heating temperature is 1243℃, the heating time is 49min, and the hot rolling mill is used for rolling. The finishing rolling temperature is 890℃, and the finished product thickness is 8mm. The laminar cooling adopts front dispersion cooling, the cooling rate is 19℃ / S, and the steel strip temperature is reduced to 643℃ for coiling. Finally, the product performance test is carried out.

[0026] Comparative Example 1

[0027] The smelting is carried out in a laboratory furnace. The slab heating temperature is 1238℃, the heating time is 50min, and the hot rolling mill is used for rolling. The finishing rolling temperature is 890℃, and the finished product thickness is 8mm. The laminar cooling adopts front dispersion cooling, the cooling rate is 19℃ / S, and the steel strip temperature is reduced to 650℃ for coiling. Finally, the product performance test is carried out.

[0028] Comparative Example 2

[0029] The smelting was carried out in a laboratory furnace. The slab heating temperature was 1260℃, the heating time was 51min, and the hot rolling mill was used for rolling. The finishing rolling temperature was 887℃, and the finished product thickness was 8mm. The laminar cooling adopted front dispersion cooling, the cooling rate was 18℃ / S, and the steel strip temperature was reduced to 646℃ for coiling. Finally, the product performance test was carried out.

[0030] Table 1 Chemical composition of Examples 1 to 3 of the present invention (wt%)

[0031]

[0032] Note: The content ratio of La and Ce in mixed rare earth is 1:1.

[0033] The steel coils of Examples 1 to 3 of the present invention were tested for mechanical properties, and the test results are shown in Table 2.

[0034] Table 2 Mechanical properties of the steel coils of Examples 1 to 3 of the present invention

[0035]

[0036] It can be seen from the data in Table 2 that the mechanical properties and process properties of the low-cost, high-strength rare earth weathering steel produced according to the method provided by the present invention meet the requirements of the agreement signed with the user.

[0037] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing 6-8mm low-cost high-strength rare earth weathering steel, characterized in that: include: (1) Smelting-continuous casting production workers; The chemical composition of the molten steel by mass percentage is: C: 0.11-0.13%, Si: 0.25-0.35%, Mn: 0.5-0.6%, P: 0.06-0.08%, S: ≤0.008%, Cu: 0.20-0.25%, Cr: 2.1-2.3%, Ti: 0.12-0.14%, La / Ce: 20-80ppm, Alt: 0.020-0.050%; the rest is Fe and unavoidable impurities; (2) Hot rolling production process: ingot casting - induction heating furnace - laboratory rolling mill - laminar cooling - simulated coiling; ingot furnace temperature is 1250±20℃, the final rolling temperature of finishing rolling is 900℃, the cooling rate is 10-20℃ / S, and the thickness of hot rolled steel strip is 6-8mm; cooling adopts laminar cooling equipment, front dispersed cooling mode, and the coiling temperature is 650±10℃.

2. The method for producing 6-8 mm low-cost high-strength rare earth weathering steel according to claim 1, characterized in that: The chemical composition of the weathering steel by mass percentage is: C: 0.12%, Si: 0.27%, Mn: 0.53%, P: 0.072%, S: 0.004%, Cu: 0.22%, Cr: 2.20%, Ti: 0.12%, La / Ce: 50ppm, Alt: 0.030%; the rest is Fe and unavoidable impurities.

3. The method for producing 6-8 mm low-cost high-strength rare earth weathering steel according to claim 1, characterized in that: The chemical composition of the weathering steel in mass percentage is: C: 0.12%, Si: 0.27%, Mn: 0.52%, P: 0.070%, S: 0.003%, Cu: 0.21%, Cr: 2.21%, Ti: 0.12%, La / Ce: 44ppm, Alt: 0.031%; the rest is Fe and unavoidable impurities.

4. The method for producing 6-8 mm low-cost high-strength rare earth weathering steel according to claim 1, characterized in that: The chemical composition of the weathering steel by mass percentage is: C: 0.12%, Si: 0.25%, Mn: 0.59%, P: 0.073%, S: 0.003%, Cu: 0.25%, Cr: 2.18%, Ti: 0.12%, La / Ce: 53ppm, Alt: 0.030%; the rest is Fe and unavoidable impurities.

5. The method for producing 6-8 mm low-cost high-strength rare earth weathering steel according to claim 2, characterized in that: The rolling is carried out using the traditional 2250 hot rolling production line; the slab heating temperature is 1260℃, the heating time is 50min, and the hot rolling mill is used for rolling; the finishing rolling temperature is 897℃, and the finished product thickness is 8mm; laminar cooling uses front dispersion cooling, the cooling rate is 20℃ / S, and the steel strip temperature is reduced to 656℃ for coiling; finally, the product performance is tested.

6. The method for producing 6-8 mm low-cost high-strength rare earth weathering steel according to claim 3, characterized in that: The rolling is carried out using a traditional 2250 hot rolling production line; the slab heating temperature is 1250°C, the heating time is 50 minutes, and the hot rolling mill is used for rolling; the finishing rolling temperature is 900°C, and the finished product thickness is 8mm; laminar cooling uses front dispersion cooling, the cooling rate is 18°C / S, and the steel strip temperature is reduced to 659°C for coiling; finally, the product performance is tested.

7. The method for producing 6-8 mm low-cost high-strength rare earth weathering steel according to claim 4, characterized in that: The rolling is carried out using the traditional 2250 hot rolling production line; the slab heating temperature is 1243°C, the heating time is 49 minutes, and the hot rolling mill is used for rolling; the finishing rolling temperature is 890°C, and the finished product thickness is 8mm; laminar cooling uses front dispersion cooling, the cooling rate is 19°C / S, and the steel strip temperature is reduced to 643°C for coiling; finally, the product performance is tested.

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