Production method of wind power steel plate capable of improving seawater corrosion resistance

Abstract

The invention relates to a production method of a wind power steel plate with seawater corrosion resistance, and belongs to the technical field of steel manufacturing. The steel comprises, by weight, 0.15%-0.17% of C, smaller than or equal to 0.15% of Si, 1.10%-1.20% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.005% of S, 0.020%-0.050% of Al, 0.010%-0.020% of Nb, 0.008%-0.02% of Ti, 0.005%-0.010% of Ce and smaller than or equal to 0.38% of Ceq, the structure of the steel plate is acicular ferrite and pearlite, the yield strength of the steel plate is larger than or equal to 355 MPa, the tensile strength is 460-630 MPa, the ductility is larger than or equal to 21%, and the ballistic energy at-20 DEG C is larger than or equal to 34 J in the longitudinal direction and larger than or equal to 24 J in the transverse direction. The method comprises the key process steps of converter smelting, LF furnace refining, RH furnace vacuum refining, continuous casting and rolling, and the technical problem that the corrosion speed of the steel grade is high in the seawater environment is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel manufacturing and relates to a method for producing a steel plate for wind power with seawater corrosion resistance. Background Art

[0002] About 2% of the Earth's solar energy is converted into wind energy, the primary form of which is wind power. Wind power is environmentally friendly, low-cost, and highly profitable.

[0003] The steel plates used to make wind turbine towers are known as wind turbine steel. However, existing wind turbine steel generally lacks consideration for corrosion resistance. For offshore use, it requires an anti-corrosion coating, which significantly impacts the health of coating workers and the marine ecosystem, and requires extensive maintenance. While some innovative technologies have produced steel with atmospheric corrosion resistance, they may not be suitable for use in seawater. Furthermore, the steel's strength after normalizing may not meet the required 420 MPa, or its service temperature may be as low as -20°C.

[0004] Therefore, it is necessary to develop steel materials that are highly resistant to seawater corrosion and have a long service life. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for producing a steel plate for wind power with seawater corrosion resistance, so as to solve the technical problem that the steel plate corrodes quickly in a seawater environment.

[0006] The technical solution of the present invention: A method for producing a seawater corrosion-resistant steel plate for wind power generation, wherein the chemical composition of the steel is as follows by weight: C = 0.15% to 0.17%, Si = 0.15% to 0.35%, Mn = 1.10% to 1.20%, P ≤ 0.015%, S ≤ 0.005%, Al = 0.020% to 0.050%, Nb = 0.010% to 0.020%, Ti = 0.008% to 0.02%, Ce = 0.003% to 0.015%, Ceq ≤ 0.38%, and the remainder is Fe and essential impurities; the method comprises the following process steps: (1) Converter smelting: BOF converter smelting is adopted, the oxygen content at the tapping end point is ≤500ppm, aluminum iron, silicon manganese are added during the tapping process for deoxidation and alloying, and lime is added during the tapping process to make primary slag; (2) LF furnace refining: lime, synthetic refining slag, and aluminum particles are added to the LF furnace to produce high-basicity reducing slag, which is smelted for 40 to 60 minutes with argon blowing and stirring at the bottom during the whole process. No calcium treatment is performed after the LF refining is completed. (3) RH furnace vacuum refining: The RH furnace molten steel is kept at a high vacuum degree of ≤67Pa for ≥12min. When the vacuum is maintained for 8min, 1-3kg of rare earth cerium iron alloy is added to ton of steel. When the vacuum is maintained for 10min, 0.3-0.5kg of silicon calcium barium alloy is added to ton of steel. After the vacuum treatment is completed, soft argon is blown for 12-20min. (4) Continuous casting: Protected pouring throughout the entire process, the tundish superheat is controlled at 8-15°C, dynamic soft reduction is applied at the end of solidification of the slab, and the macroscopic center segregation of the slab meets the requirements of Class C within 2.0 in YB / T 4003-2016 "Grade of Macroscopic Defects of Continuously Cast Steel Slabs"; (5) Rolling: The heating furnace temperature is ≤1220℃, and a two-stage rolling process is adopted. The starting rolling temperature of the rough rolling stage is 950-1030℃, the starting rolling temperature of the finishing rolling stage is 830-850℃, and the final rolling temperature is 780-820℃; (6) Cooling: After rolling, ACC laminar flow accelerated cooling is adopted, and the final cooling temperature is 620-650℃.

[0007] The present invention has the beneficial effect of treating inclusions in the steel with rare earth elements by adding rare earth alloying elements to molten steel. This treatment reduces the corrosion rate of the steel in seawater environments due to the formation of a dense rust layer on the surface of the steel, which protects the matrix. Furthermore, the corrosion rate decreases with increasing rare earth Ce content. The addition of an appropriate amount of rare earth alloys to the steel improves the seawater corrosion resistance of offshore wind power steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is the surface scanning analysis result of inclusions in Example 1.

[0009] Figure 2 This is the result of surface scanning analysis of inclusions in Example 2.

[0010] Figure 3 This is the seawater corrosion diagram of steel plate.

[0011] Figure 4 This is a graph showing the relationship between the mass loss of steel plates due to seawater corrosion and the corrosion time.

[0012] Figure 5 This is a graph showing the relationship between the seawater corrosion rate of steel plates and the corrosion time. DETAILED DESCRIPTION

[0013] The following further describes the invention with reference to the embodiments. Example 1

[0014] A method for producing seawater corrosion-resistant steel plates for wind power generation includes preparing smelting raw materials based on the composition of the steel grade: blast furnace iron, silicon-manganese alloy (68% manganese content), electrolytic aluminum blocks (98.5% aluminum content), ferroniobium (60% niobium content), recarburizer (97% carbon content), 150 kg of rare earth cerium alloy (10% cerium content), and 45 kg of silicon-calcium-barium alloy (14% calcium content). The key steps of the production process include: (1) Converter smelting: BOF converter smelting is used, the oxygen content at the tapping end point is set at 351ppm, silicon manganese and aluminum iron are added during the tapping process for alloying and deoxidation, and lime is added during the tapping process to make primary slag; (2) LF furnace refining: lime, synthetic refining slag, and aluminum particles are added to the LF furnace to produce high-basicity reducing slag, which is smelted for 50 minutes with argon blowing and stirring at the bottom during the whole process. No calcium treatment is performed after the LF refining is completed. (3) RH furnace vacuum refining: The RH furnace molten steel is kept under high vacuum (pressure ≤ 67Pa) for 12 minutes. When the vacuum is maintained for 8 minutes, 1 kg of rare earth cerium iron alloy is added to each ton of steel. When the vacuum is maintained for 10 minutes, 0.3 kg of silicon calcium barium alloy is added to each ton of steel. After the vacuum treatment is completed, soft argon is blown for 13 minutes. (4) Continuous casting: Protected pouring throughout the entire process, the tundish superheat is controlled at 8-15°C, dynamic soft reduction is applied at the end of solidification of the slab, and the macroscopic center segregation of the slab meets the requirements of Class C 1.0 in YB / T 4003-2016 "Grade Chart for Macroscopic Defects in Continuously Cast Steel Slabs"; (5) Rolling: The heating furnace temperature is ≤1220℃, and a two-stage rolling process is adopted. The starting rolling temperature of the rough rolling stage is 950-1030℃, the starting rolling temperature of the finishing rolling stage is 830-850℃, and the final rolling temperature is 780-820℃; (6) Cooling: After rolling, ACC laminar flow accelerated cooling is adopted, the final cooling temperature is 620-650℃, and the cooling bed is air-cooled to room temperature.

[0015] The rare earth Ce content in the steel plate of Example 1 is 32ppm, and the surface scanning results of the inclusions in the steel are as follows: Figure 1 , sulfides are transformed into rare earth sulfides; the steel plates are resistant to seawater corrosion for 7 days, 14 days, 32 days and 56 days. Figure 3 (e), (f), (g), (h), compared with the steel plate without rare earth addition and the same seawater corrosion time, Figure 3 (a), (b), (c), (d), when the rare earth treated steel plate was corroded in seawater for 28 days, the area of ​​the reddish brown rust layer decreased, as shown in Figure 3. Figure 3 (g); Compare the mass loss of steel plate as follows Figure 4 The corrosion rate of rare earth treated steel plate in seawater is lower than that of non-rare earth treated steel plate after 28 days, and as the corrosion time increases, the gap between the two increases further after 56 days. Figure 5 In the early stage of seawater corrosion, the corrosion rates of steel plates with and without rare earth addition were relatively fast. After a period of corrosion, both began to decline, but the corrosion rate of steel plates with rare earth addition decreased more. As the corrosion time continued to extend, by 56 days, the corrosion rate of steel plates with rare earth addition was even lower than that of steel plates without rare earth addition. Example 2

[0016] A method for producing seawater corrosion-resistant steel plates for wind power generation uses the following steps: first, prepare the following raw materials based on the composition of the steel: molten iron from a blast furnace, silicon-manganese alloy (68% manganese content), electrolytic aluminum blocks (98.5% aluminum content), ferroniobium (60% niobium content), recarburizer (97% carbon content), rare earth cerium alloy (10% cerium content), 2 kg of raw materials added per ton of steel, and 45 kg of silicon-calcium-barium alloy (14% calcium content). The key steps of the production process include: (1) Converter smelting: BOF converter smelting is used, the oxygen content at the tapping end point is set at 321ppm, silicon manganese and aluminum iron are added during the tapping process for alloying and deoxidation, and lime is added during the tapping process to make primary slag; (2) LF furnace refining: lime, synthetic refining slag, and aluminum particles are added to the LF furnace to produce high-basicity reducing slag. The smelting process lasts for 48 minutes, with argon blowing and stirring at the bottom of the furnace. No calcium treatment is performed after the LF refining is completed. (3) RH furnace vacuum refining: The RH furnace molten steel is kept under high vacuum (pressure ≤ 67Pa) for 12 minutes. When the vacuum is maintained for 8 minutes, 2 kg of rare earth cerium iron alloy is added to each ton of steel. When the vacuum is maintained for 10 minutes, 0.3 kg of silicon calcium barium alloy is added to each ton of steel. After the vacuum treatment is completed, soft argon is blown for 14 minutes. (4) Continuous casting: Protected pouring throughout the entire process, the tundish superheat is controlled at 8-15°C, dynamic soft reduction is applied at the end of solidification of the slab, and the macroscopic center segregation of the slab meets the requirements of Class C 1.0 in YB / T 4003-2016 "Grade Chart for Macroscopic Defects in Continuously Cast Steel Slabs"; (5) Rolling: The heating furnace temperature is ≤1220℃, and a two-stage rolling process is adopted. The starting rolling temperature of the rough rolling stage is 950-1030℃, the starting rolling temperature of the finishing rolling stage is 830-850℃, and the final rolling temperature is 780-820℃; (6) Cooling: After rolling, ACC laminar flow accelerated cooling is adopted, the final cooling temperature is 620-650℃, and the cooling bed is air-cooled to room temperature.

[0017] The rare earth Ce content in the steel plate of Example 2 is 74ppm, and the surface scanning results of the inclusions in the steel are as follows: Figure 2 , sulfides are transformed into rare earth sulfides; the steel plates are resistant to seawater corrosion for 7 days, 14 days, 32 days and 56 days. Figure 3 (i), (j), (k), (l), compared with the steel plate without rare earth addition and the same seawater corrosion time, Figure 3 (a), (b), (c), (d), when the rare earth treated steel plate was corroded in seawater for 28 days, the reddish brown rust layer area was smaller, such as Figure 3 (k); Compare the mass loss of steel plate as Figure 4 The corrosion rate of rare earth treated steel plate in seawater is lower than that of non-rare earth treated steel plate after 28 days, and as the corrosion time increases, the gap between the two increases further after 56 days. Figure 5In the early stage of seawater corrosion, the corrosion rates of steel plates with and without rare earth addition were relatively fast. After a period of corrosion, both began to decline, but the corrosion rate of steel plates with rare earth addition decreased more. As the corrosion time continued to extend, by 56 days, the corrosion rate of steel plates with rare earth addition was even lower than that of steel plates without rare earth addition.

[0018] Compared with Example 1, as the rare earth Ce content of the steel plate increases, the mass loss of the steel plate due to seawater corrosion is lower. Figure 4 , the corrosion rate is also lower as Figure 5 .

[0019] Table 1 Chemical composition of example steel (wt%) .

Claims

1. A method for producing a steel plate for wind power generation with improved seawater corrosion resistance, characterized in that: The chemical composition of the steel is C=0.15%~0.17%, Si=0.15%~0.35%, Mn=1.10%~1.20%, P≤0.015%, S≤0.005%, Al=0.020%~0.050%, Nb=0.010%~0.020%, Ti=0.008%~0.02%, Ce=0.003%~0.015%, Ceq≤0.38%, and the rest is Fe and essential impurities; The process steps include: (1) Converter smelting: BOF converter smelting is adopted, the oxygen content at the tapping end point is ≤500ppm, aluminum iron, silicon manganese are added during the tapping process for deoxidation and alloying, and lime is added during the tapping process to make primary slag; (2) LF furnace refining: lime, synthetic refining slag, and aluminum particles are added to the LF furnace to produce high-basicity reducing slag, which is smelted for 40 to 60 minutes with argon blowing and stirring at the bottom during the whole process. No calcium treatment is performed after the LF refining is completed. (3) RH furnace vacuum refining: The RH furnace molten steel is kept at a high vacuum degree of ≤67Pa for ≥12min. When the vacuum is maintained for 8min, 1-3kg of rare earth cerium iron alloy is added to ton of steel. When the vacuum is maintained for 10min, 0.3-0.5kg of silicon calcium barium alloy is added to ton of steel. After the vacuum treatment is completed, soft argon is blown for 12-20min. (4) Continuous casting: Protected pouring throughout the entire process, the tundish superheat is controlled at 8-15°C, dynamic soft reduction is applied at the end of solidification of the slab, and the macroscopic center segregation of the slab meets the requirements of Class C within 2.0 in YB / T 4003-2016 "Grade of Macroscopic Defects of Continuously Cast Steel Slabs"; (5) Rolling: The heating furnace temperature is ≤1220℃, and a two-stage rolling process is adopted. The starting rolling temperature of the rough rolling stage is 950-1030℃, the starting rolling temperature of the finishing rolling stage is 830-850℃, and the final rolling temperature is 780-820℃; (6) Cooling: After rolling, ACC laminar flow accelerated cooling is adopted, and the final cooling temperature is 620-650℃.

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