Efficient precise-control smelting method for GF400 photovoltaic steel

Abstract

The invention provides an efficient precise control smelting method of GF400 photovoltaic steel, which comprises four steps of slag washing, argon blowing, LF refining and continuous casting, and through detailed control of parameters in each step, the oxygen content in molten steel is effectively reduced, and the effects of slag adsorption and inclusion separation are improved, so that the purity of the molten steel is controlled, and the quality of the molten steel is improved. The content of molten steel is controlled to be 0.10%-0.14% of C, 0.08%-0.12% of Si, 0.45%-0.55% of Mn, smaller than or equal to 0.015% of S, smaller than or equal to 0.025% of P, 0.020%-0.025% of Alt, larger than or equal to 0.040% of Ti, smaller than or equal to 0.0020% of T [O] and smaller than or equal to 0.0040% of N. Through multi-node control of the whole smelting process, the effects of precise control of steel components, grain refinement and mechanical property improvement are achieved, the yield strength of finished steel is stably and greatly improved to 400 MPa or above, the finished steel can meet the use requirement of photovoltaic steel, and the stability and reliability of the quality of products in batches are guaranteed.

Description

Technical Field

[0002] This invention relates to the field of iron and steel metallurgy technology, and in particular to a highly efficient and precise smelting method for GF400 photovoltaic steel. Background Technology

[0004] Photovoltaic steel is a special type of steel specifically designed for photovoltaic (PV) mounting systems and building-integrated photovoltaics (BIPV). It boasts excellent performance and high strength, and is widely used in the new energy sector. With the continuous growth of new PV installations in my country, the steel required for PV mounting systems is expected to increase from 2 million tons to 4 million tons, with usage increasing year by year. The development direction of PV mounting systems mainly focuses on high strength, lightweight design, and green technology. Although Q235B steel plates and hot-dip galvanized plates are currently the main materials used in PV mounting systems, they are expected to be replaced in the future by lighter, stronger, and more corrosion-resistant GF350 and GF400 steels, with yield strengths reaching over 350MPa and 400MPa respectively, far exceeding the 235MPa of Q235B. Under the same load, high-strength steel can reduce material usage (thinner cross-sections or lighter structures), reducing the weight of the mounting system by 20%-30%. Based on a 1GW PV project, using GF400 can save approximately 15% of steel, reducing total costs by 5%-8%. High-strength steel production has lower carbon emissions (energy consumption reduced by 10%-15%), which meets the requirements of the green supply chain in the photovoltaic industry; under China's "dual carbon" goals, lightweight high-strength materials are more encouraged by policy.

[0005] Currently, most photovoltaic steels achieve their strength by adding trace amounts of elements such as Nb, and / or V, and / or Ti to the steel. These elements form carbides and nitrides with C and N, which precipitate at the ferrite interface or within the grains, thereby refining the grains. Examples include a weathering steel disclosed in Chinese Patent CN202510903327.8, its production method, and applications; and a high-strength weathering steel for photovoltaic brackets and its preparation of thin-gauge steel plates disclosed in Chinese Patent CN202410804211.4. Methods and production methods for weathering steel used in photovoltaic brackets, as disclosed in Chinese Patent CN202210071486.2, both improve steel properties by adding niobium. Similarly, methods for preparing high-strength waterproof photovoltaic brackets, as disclosed in Chinese Patent CN202310937072.8, and zinc-aluminum-magnesium alloy coated steel plates / strips for photovoltaic structure manufacturing, as disclosed in Chinese Patent CN202511069027.0, all utilize vanadium and other elements to enhance steel strength. However, metals like niobium and vanadium are significantly more expensive than titanium, greatly increasing steel costs.

[0006] Titanium's relatively low price significantly reduces the cost of microalloying. However, titanium is chemically reactive and readily forms large inclusions with elements such as oxygen, sulfur, and nitrogen in steel. Reducing the inclusion content and controlling the morphology of inclusions are key concerns for this steel grade.

[0007] Chinese patent CN202511166446.6 discloses a 420MPa grade steel strip for high corrosion resistance photovoltaic brackets, based on Ti microalloying and a low-aluminum, high-magnesium coating synergistic reinforcement, and its preparation method. Addressing the needs of distributed photovoltaic brackets, a microalloying composition with Ti as the core element was designed. This composition was synergistically strengthened with a low-aluminum, high-magnesium micro-titanium coating system to produce a 420MPa grade steel strip, which is then used in high corrosion resistance photovoltaic brackets. This steel exhibits balanced performance and excellent corrosion resistance. Simultaneously, controlled rolling and cooling, along with low-temperature annealing, are employed during the preparation process to address the poor formability issues of traditional steels. A low-temperature fast plating process is used to reduce energy consumption and improve production efficiency. However, the oxygen content in the steel produced by this process is above 0.0020%, resulting in a high number of inclusions and affecting the service life of the final product. Therefore, it is essential to combine this process with controlled plating technology to meet the requirements for photovoltaic bracket steel.

[0008] Therefore, how to control the inclusions formed by active Ti during the smelting process and achieve a yield strength of 400 MPa in the steel has become an important challenge for improving the quality and reducing the cost of photovoltaic steel. Summary of the Invention

[0010] To address the aforementioned problems in the existing technology, the present invention aims to provide a highly efficient and precise smelting method for GF400 photovoltaic steel, which effectively controls the inclusions of active Ti elements in the steel, improves the grain size of the steel, and significantly increases the yield strength of the steel.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0012] A highly efficient and precise smelting method for GF400 photovoltaic steel includes the following steps:

[0013] S1, Slag Washing Stage

[0014] Molten iron is poured into a converter for smelting. When the carbon content is blown to 0.05%~0.08%, it is ready to be tapped. Before tapping, quicklime and fluorite balls are added to the ladle to adjust the slag. During the tapping process, aluminum ingots, silicon-manganese alloy and carbon raisers are added to the ladle to adjust the composition of the molten steel so that the oxygen content of the molten steel is controlled below 20 ppm.

[0015] S2, Argon Blowing Stage

[0016] After tapping, the ladle is moved to the argon station and bottom-blown with argon for 30 seconds. The oxygen content in the steel is then measured. Based on the measured oxygen content, aluminum wire is replenished in one go. After feeding the wire, the total aluminum content in the steel is controlled at 0.020%-0.030%, and then it is sent to the LF furnace.

[0017] S3, Refining Stage

[0018] The LF refining temperature of the molten steel is controlled at 1610℃-1620℃. Lime and fluorite are added to form slag and remove inclusions. The composition of the molten steel is adjusted by adding silicon-manganese alloy, carbon raiser and ferrotitan.

[0019] S4, Continuous Casting Stage

[0020] Molten steel is fed into a continuous casting machine and cast into a billet; the continuous casting speed is constant and controlled at 1.10-1.20 m / min.

[0021] In step S1, the sulfur content in the molten iron used for smelting is controlled to be S≤0.025%, and the silicon-manganese alloy added during tapping is FeMn65Si17 type silicon-manganese alloy, and the carbon raiser is C92 carbon raiser.

[0022] In step S1, the amount of aluminum ingots added is 0.72-0.93 kg / t, and conforms to the following calculation formula:

[0023]

[0024] In the formula:

[0025] η: Aluminum recovery rate after steel tapping from converter, ranging from 30% to 45%;

[0026] M: Mass of aluminum ingot, in kg / t;

[0027] W0: Initial oxygen content at tapping, in ppm;

[0028] Wt: Target oxygen content, in ppm.

[0029] In step S2, when steel is fed into the LF furnace, the argon blowing station must prepare aluminum granules / aluminum chips and silicon carbide, and evenly sprinkle aluminum chips / aluminum granules and silicon carbide on the slag surface of the molten steel. After stirring and slag formation, the argon gas is turned off.

[0030] Step S3 includes two heating stages:

[0031] S31, First heating stage

[0032] In the first heating stage, the suitable temperature of the molten steel is 1600℃-1610℃; the temperature rise of the molten steel is controlled by controlling the magnitude of the electrode current, and the heating rate is in the range of 4℃ / min-7℃ / min, to ensure that the temperature of the molten steel reaches the range of 1600℃-1610℃ by the 10th minute.

[0033] For the first two minutes of the first heating stage, silicon carbide is evenly sprinkled into the molten steel; after heating for 2 minutes, observe whether the top slag has melted. After the top slag has melted, add 1.72 kg / t of lime and 1.33 kg / t of fluorite into the molten steel; in addition, during the first heating stage from 2 to 6 minutes, aluminum shavings are evenly sprinkled until the heating is over.

[0034] After the aluminum shavings are added in the first heating stage, observe the slag. If the slag is black, it means that the deoxidation is not up to standard, and aluminum shavings still need to be added in the second heating stage. If the slag is white or grayish-white, it means that the deoxidation is up to standard, and aluminum shavings do not need to be added in the second heating stage.

[0035] Temperature measurement and sampling are performed at the 10th minute. If the sulfur content in the molten steel exceeds 0.014%, continue blowing argon at a large volume of 400-700 NL / min for two minutes before entering the second heating stage. If the sulfur content in the molten steel is less than 0.014%, proceed directly to the next heating stage.

[0036] S32, Second heating stage

[0037] The target steel temperature for the second heating stage is 1610℃-1620℃. The steel temperature is controlled by adjusting the electrode current, with a heating rate of 5℃ / min-7℃ / min, to ensure that the target heating temperature is reached within the first 5 minutes of the second heating stage. Once the molten steel has stabilized at the target temperature, steel-slag samples are taken for analysis immediately.

[0038] If the slag adhesion is found to be unqualified during the first heating stage, aluminum chips are evenly sprinkled for deoxidation during the second heating stage. After the slag adhesion is qualified, 1.5-2.0 Kg / t of FeTi30 type ferrotitanium is added to the molten steel and gently blown for 10-15 min.

[0039] In the refining step, the refining time is greater than 30 min, and the white slag time is greater than 10 min; the total amount of aluminum shavings sprinkled in the two heating stages is 0.1 kg / t; the flow rate of soft-blown argon is controlled within the range of 20–60 NL / min. After adding ferrotitanium, the mass percentage of titanium in the molten steel is limited to (Ti)% + (Al)% + (Ca)% - 3.4 (N)% - 3 (S)% - (O)% ≥ 0.03%.

[0040] After refining, the final composition of the molten steel is: C 0.10-0.14%, Si 0.08-0.12%, Mn 0.45-0.55%, S≤0.015%, P≤0.025%, Alt 0.020-0.025%, Ti≥0.040%, T[O]≤0.0020%, N%≤0.0040%.

[0041] Through the application of the above-mentioned multiple technical means, the present invention has achieved the following technical advancements:

[0042] This invention provides a highly efficient and precise smelting method for GF400 photovoltaic steel. Through multi-node control of the entire smelting process, the steel composition is precisely controlled, effectively controlling the inclusions of active Ti elements in the steel. The yield strength of the finished steel is stably and significantly increased to over 400 MPa, which meets the requirements for photovoltaic steel use and ensures the stability and reliability of product quality between batches.

[0043] In this invention, Ti combines with N to form TiN particles due to their strong affinity. These TiN particles anchor the austenite grain boundaries, inhibiting austenite coarsening and refining the grains, thereby improving the strength of the steel. Therefore, titanium is one of the most important alloying elements in steel. However, Ti is chemically reactive and readily forms large inclusions with elements such as oxygen, sulfur, and nitrogen in the steel, affecting the stability of the steel's mechanical properties. Therefore, controlling the Ti content in the steel is particularly important. This invention specifically limits the Ti content range to (Ti)% + (Al)% + (Ca)% - 3.4 (N)% - 3 (S)% - (O)% ≥ 0.03%. This formula achieves the coupling of the influence of multiple element contents within the steel, achieving the dual effect of controlling inclusions and improving steel strength. Attached Figure Description

[0045] Figure 1a , Figure 1b This is a metallographic morphology diagram of Embodiment 1 of the present invention;

[0046] Figure 2a , Figure 2b This is a metallographic morphology diagram of Embodiment 2 of the present invention;

[0047] Figure 3a , Figure 3b This is a metallographic morphology diagram of Example 3 of the present invention;

[0048] Figure 4a , Figure 4b This is a metallographic morphology diagram of Comparative Example 1 of the present invention;

[0049] Figure 5a , Figure 5b , Figure 5c This is a metallographic morphology diagram of Comparative Example 2 of the present invention. Detailed Implementation

[0051] The present invention will now be described in further detail.

[0052] It should be noted that the content control ranges for each element in molten iron and molten steel given in this invention refer to mass content (wt%). Furthermore, the unit for the amount of smelting aids added is kg / t, where t represents ton of steel.

[0053] A highly efficient and precise smelting method for GF400 photovoltaic steel includes four stages: slag washing, argon blowing, LF furnace refining, and continuous casting.

[0054] S1, Slag Washing Stage

[0055] Molten iron is poured into a converter for smelting. When the carbon content is blown to 0.05%~0.08%, it is ready to be tapped. Before tapping, quicklime and fluorite balls are added to the ladle for slag adjustment. During the tapping process, aluminum ingots, silicon-manganese alloy and carbon raisers are added to the ladle to adjust the composition of the molten steel and control the oxygen content of the molten steel to be below 20 ppm.

[0056] In step S1, the sulfur content in the molten iron used for smelting is controlled to be S≤0.025%, thereby reducing the harm of sulfide inclusions to the steel by controlling the sulfur content in the steel.

[0057] Before tapping steel from the converter, 3.74-4.74 kg / t of quicklime is added to the ladle to increase desulfurization efficiency; 0.2-0.3 kg / t of fluorite balls promotes slag melting, reduces slag melting point and viscosity, and promotes the floating of inclusions.

[0058] During tapping, 0.72-0.93 kg / t of aluminum ingots are added to the ladle for deoxidation, reducing the oxygen content of the molten steel to below 20 ppm. The amount of aluminum ingots added is calculated according to the following formula:

[0059]

[0060] In the formula:

[0061] η: Aluminum recovery rate after steel tapping from converter, ranging from 30% to 45%;

[0062] M: Mass of aluminum ingot, in kg / t;

[0063] W0: Initial oxygen content at tapping, in ppm;

[0064] W t Target oxygen content, in ppm.

[0065] During tapping, 5.67-6.39 kg / t of FeMn65Si17 silicon-manganese alloy is added to adjust the silicon and manganese content in the molten steel. A carbon raiser is added at a rate of 0.41-0.52 kg / t to moderately increase the carbon content in the molten steel; the carbon raiser has a carbon content of 93% and a particle size of 2-7 mm.

[0066] It is important to emphasize that during the period from tapping to the application of the slag-blocking cone, a high flow rate of 400-600 NL / min of argon gas is injected into the bottom of the ladle for stirring to accelerate the melting of the top slag.

[0067] S2, Argon Blowing Stage

[0068] After tapping, the ladle containing molten steel is transferred to the argon station, where argon gas is used to bottom-purge and stir the molten steel to ensure uniform composition. After 30 seconds of argon blowing, the oxygen content of the molten steel is quickly measured, and aluminum wire is added in one go based on the measured aluminum content. After feeding the aluminum wire, the aluminum content in the steel is controlled within the range of 0.020%-0.030%. After sampling, the steel is fed into the LF furnace.

[0069] In step S2,

[0070] After the ladle is transferred to the argon station, the argon flow rate used to stir the molten steel is controlled at 400-700 NL / min. The argon is blown into the molten steel from the bottom through porous permeable bricks or special nozzles to generate bubbles and achieve thorough stirring.

[0071] Generally, adding 0.011 kg / t of aluminum wire to molten steel can increase the aluminum content by approximately 0.001%. During production, the aluminum wire is added in one go according to this ratio to control the aluminum content in the molten steel at 0.020-0.030%. After feeding the wire, argon is blown at a rate of 400-700 NL / min for 20 seconds to promote the dissolution of the aluminum wire.

[0072] When feeding steel into the LF furnace, the argon blowing station must prepare aluminum granules / aluminum chips and silicon carbide, and evenly sprinkle them onto the slag surface of the molten steel. After stirring and slag formation, the argon gas should be shut off. The aluminum granules / aluminum chips deoxidize the slag, improve its fluidity, stabilize the slag layer, and adjust the composition of the molten steel. Specifically, the amount of aluminum chips or granules added is 0.23 kg / t, and the amount of silicon carbide added is 0.10-0.15 kg / t. After addition, argon gas is blown at a high flow rate for 30-60 seconds to slag, with the argon flow rate controlled at 400-600 NL / min.

[0073] In step S2, argon is blown into the bottom throughout the process. Except when slag needs to be dissolved, the flow rate of argon is controlled at 200-300 NL / min to stir the composition and temperature evenly and promote the floating of inclusions.

[0074] S3, Refining Stage

[0075] The molten steel is refined in the LF furnace, with fluorite and quicklime added and argon blown at a high volume to promote slag formation. The refining temperature is 1610℃-1620℃. Before the end of refining, silicon-manganese alloy, carbon raiser, and ferrotitanium are added to adjust the composition of the molten steel.

[0076] In step S3, the composition of the molten steel entering the LF furnace is controlled within the following range: C 0.08-0.10%, Si≤0.01%, Mn0.43-0.48%, P≤0.025%, Alt 0.020-0.030%.

[0077] During the heating process of the LF furnace, argon is blown at a flow rate of 100-200 NL / min to promote the floating of inclusions. The argon blowing effect should be such that the slag surface surges without forming a crust or churning.

[0078] The silicon-manganese alloy is preferably FeMn65Si17 type silicon-manganese alloy, the carbon additive is preferably silicon carbide C92, and the ferrotitanium is preferably FeTi30 type ferrotitanium.

[0079] Regarding high-volume argon blowing, this refers to an argon flow rate of 400-600 NL / min. After high-volume argon blowing, adding fluorite and quicklime to the molten steel ensures that the refining slag has rapid slag formation and good inclusion adsorption capacity, enhances slag desulfurization and inclusion adsorption capabilities, improves the purity of the molten steel, and facilitates subsequent operations. The amount of fluorite added is 1.33 kg / t, and the amount of quicklime added is 1.72 kg / t.

[0080] The refining process specifically includes two heating stages:

[0081] 1. First heating stage

[0082] The target steel temperature for the first heating stage is 1600℃-1610℃. The temperature rise of the molten steel is controlled by adjusting the electrode current, with a heating rate in the range of 4℃ / min-7℃ / min, ensuring that the steel temperature reaches the 1600℃-1610℃ range by the 10th minute.

[0083] During the first two minutes of the first heating stage, silicon carbide is evenly sprinkled into the top slag at a total amount of 0.10-0.15 kg / t. After heating for 2 minutes, the top slag is observed to see if it has melted. If not, heating continues until it melts. Once the top slag has melted, 1.72 kg / t of lime and 1.33 kg / t of fluorite are added to the molten steel within 4 minutes. Additionally, during the first heating stage, from 2 to 6 minutes, aluminum shavings are evenly sprinkled every 20-30 seconds, with a total amount of 0.23 kg / t (it should be noted that the total amount of aluminum shavings added from the argon station is included in the calculation).

[0084] After the aluminum shavings are added in the first heating stage, observe the slag. If the slag is black, it means it is unqualified and aluminum shavings still need to be added in the second heating stage. Conversely, if the slag is not black but white or grayish-white, it means it is qualified and aluminum shavings do not need to be added in the second heating stage.

[0085] Temperature measurement and sampling are performed at the 10th minute. If the sulfur content in the molten steel exceeds 0.014%, continue blowing argon at a large volume of 400-700 NL / min for two minutes before entering the second heating stage. If the sulfur content in the molten steel is less than 0.014%, proceed directly to the next heating stage.

[0086] 2. Second heating stage

[0087] The target steel temperature for the second heating stage is 1610℃-1620℃. The temperature rise of the molten steel is controlled by adjusting the electrode current, with a heating rate within the range of 5℃ / min-7℃ / min, ensuring that the target temperature is reached within the first 5 minutes of the second heating stage. After the molten steel reaches the target temperature, samples of the slag are taken for analysis; ensuring that the refining time is greater than 30 minutes and the white slag time is greater than 10 minutes.

[0088] It should be noted that refining time is the total time from when the ladle enters the LF stage to when it leaves the LF stage. White slag time is the duration during which the slag turns white after adding reducing agents such as silicon carbide and aluminum shavings, reducing the iron oxide content in the slag to below 1%.

[0089] If the slag turns black during the first heating stage, aluminum shavings must be evenly sprinkled for deoxidation during the second heating stage, with a total amount of 0.1 kg / t sprinkled at a frequency of once every 20-30 seconds. Conversely, if the slag adhesion is acceptable, no aluminum shavings need to be added during the second heating stage. After the slag adhesion is acceptable, the refining time should continue for more than 10 minutes.

[0090] After the composition is qualified (the slag is qualified and the sulfur content is less than 0.014%), add 0.45-0.55 kg / t of silicon-manganese alloy, 0.25-0.30 kg / t of carbon raiser, and 1.5-2.0 kg / t of FeTi30 type ferrotitanium to the molten steel. Soft blow for 10-15 min, and control the flow rate of soft blow argon gas in the range of 20-60 NL / min.

[0091] Generally, silicon-manganese alloy and carbon raiser are added first to adjust the C, Si and Mn content in the molten steel, and then ferrotitanium is added last to ensure a high yield of the most expensive metal, titanium.

[0092] After adding ferrotitanium, the mass percentage of titanium in the molten steel is limited to (Ti)% + (Al)% + (Ca)% - 3.4(N)% - 3(S)% - (O)% ≥ 0.03%, ensuring the strengthening effect of effective titanium.

[0093] After refining, the final composition of the molten steel is: C 0.10-0.14%, Si 0.08-0.12%, Mn 0.45-0.55%, S≤0.015%, P≤0.025%, Alt 0.020-0.025%, Ti≥0.040%, T[O]≤0.0020%, N%≤0.0040%.

[0094] S4, Continuous Casting Stage

[0095] Molten steel is fed into a continuous casting machine and cast into a billet; the continuous casting speed is constant and controlled at 1.10-1.20 m / min.

[0096] In step S4, the control of the liquid level in the crystallizer is stabilized as follows: the target fluctuation of the liquid level in the crystallizer is within the range of -3mm to +3mm.

[0097] It is important to emphasize that the first three heats in the tundish should be filled with sufficient covering agent to reduce steel oxidation, and high-viscosity, low-carbon protective slag should be used. The argon flow rate of the stopper rod should be adjusted to the minimum, the bushing should be properly aligned, protective casting should be carried out, and sufficient covering agent should be added to the tundish for full liquid level operation.

[0098] The present invention will be further explained and illustrated below through examples.

[0099] Example 1

[0100] A GF400 photovoltaic steel is smelted according to the following method:

[0101] S1, Slag Washing Stage

[0102] The molten iron in the blast furnace has an S content of 0.022% and a P content of 0.180%, and is treated in a blast furnace.

[0103] 87 tons of molten iron and 17 tons of scrap steel were fed into the converter for smelting; the ladle was positioned, and 400 kg of quicklime and 25 kg of fluorite balls were added to it. Steel was tapped when the carbon content reached 0.051%.

[0104] During the tapping process, 80 kg of aluminum ingots, 45 kg of carbon raiser, and 590 kg of FeMn65Si17 type silicon-manganese alloy were added to the ladle. Testing showed that the oxygen content of the molten steel in the ladle was 14.1 ppm, below 20 ppm, so no further aluminum ingots were added. From the tapping moment until the addition of the slag-blocking cone, the ladle was agitated with argon gas at a flow rate of 500 NL / min. The final steel composition was: C=0.093%, P=0.015%, S=0.016%; the steel temperature was 1601℃.

[0105] S2, Argon Blowing Stage

[0106] After tapping, the ladle containing molten steel is transferred to the argon station, where it is stirred with argon gas. After 30 seconds, an oxygen probe is inserted into the molten steel, and the oxygen content is quickly measured to be 14.1 ppm. 60 m of aluminum wire is fed in, with an aluminum content of 0.339 kg / m. Argon is blown at a volume of 500 NL / min for 20 seconds to ensure the aluminum wire is fully melted. A sample is taken for testing, and the aluminum content in the molten steel is 0.028%, which meets the requirements. Then, 22 kg of aluminum shavings and 12 kg of silicon carbide are added to the slag. After the addition is complete, the argon gas is stirred for 40 seconds, then the argon gas is turned off, and the steel is loaded.

[0107] S3, Refining Stage

[0108] The molten steel is refined in the LF furnace and argon is blown at a flow rate of 150 NL / min after entering the station to ensure that the slag surface is turbulent and does not form a crust; the temperature of the molten steel entering the station is 1568℃; the target temperature for the first heating stage is 1610℃, and the aluminum content of the molten steel is in the range of 0.025-0.035%.

[0109] Increase the temperature of the lower electrode;

[0110] After heating for 2 minutes, observe that the top slag has melted; add 129 kg of fluorite and 167 kg of quicklime into the slag, and complete the addition within 4 minutes. Then blow argon at a high volume of 600 NL / min for 20-30 seconds to promote slag formation.

[0111] During the first two minutes of the first heating stage, 0.5 kg of silicon carbide was evenly sprayed, and the total amount of silicon carbide sprayed was 12 kg.

[0112] Since aluminum shavings had already been added to the slag in the argon station, direct observation of the slag during the two to six-minute period of the first heating stage revealed that the slag was black and unqualified. Therefore, aluminum shavings need to be added again during the second heating stage.

[0113] In the second heating stage, the temperature was increased at a rate of 5-7℃ / min for 5 minutes, reaching 1610℃. During the second heating stage, 8 kg of aluminum shavings were evenly sprinkled, for a total of 30 kg of aluminum shavings sprinkled in both stages. After the molten steel reached the target temperature, the sulfur content of the molten steel was tested and found to be 0.010%. Then, 50 kg of silicon-manganese alloy, 28 kg of C92 carbon raiser, and 155 kg of FeTi30 type ferrotitanium were added.

[0114] After adding ferrotitanium, samples were taken to determine the composition of the molten steel: C 0.119%, Mn 0.509%, Si 0.104%, S 0.007%, P 0.018%, Alt 0.027%, Ti 0.048%, Ca 0.0002%, T[O] 0.0012%, N 0.0030%. The final composition was then used in calculations.

[0115] (Ti)% + (Al)%+ (Ca) %-3.4 (N)%-3(S)%- (O)%

[0116] =0.048% + 0.027% + 0.0002% - 3.4 × 0.0030% - 3 × 0.007% - 0.0012%

[0117] =0.0428% ≥ 0.03%, which meets the specified requirements. The density of inclusions in the steel is 35.5 inclusions / mm². 2 .

[0118] The total heating time for the refining process was 14 minutes, the refining time was 39 minutes, the soft blowing time was 15 minutes, the soft blowing argon flow rate was 60 NL / min, and the outlet temperature was 1590℃.

[0119] S4, Continuous Casting Stage

[0120] Molten steel is fed into a continuous casting machine and cast into a billet; the continuous casting speed is constant at 1.20 m / min and the superheat is 33℃.

[0121] The final product composition is: C 0.121%, Mn 0.522%, Si 0.084%, S 0.007%, P 0.018%, Alt 0.026%, Ti 0.044%, T[O] 0.0011%, N 0.0029%, which meets the composition requirements of this steel grade.

[0122] Example 2

[0123] A GF400 photovoltaic steel is smelted according to the following method:

[0124] S1, Slag Washing Stage

[0125] The molten iron in the blast furnace has an S content of 0.023% and a P content of 0.190%, and is treated in a blast furnace.

[0126] 88 tons of molten iron and 16.9 tons of scrap steel were fed into the converter for smelting; the ladle was positioned, and 400 kg of quicklime and 25 kg of fluorite balls were added to it. Steel was tapped when the carbon content reached 0.055%.

[0127] During the tapping process, 80 kg of aluminum ingots, 48 ​​kg of carbon raiser, and 592 kg of FeMn65Si17 type silicon-manganese alloy were added to the ladle. Testing revealed that the oxygen content of the molten steel in the ladle was 14.8 ppm. From the tapping moment until the addition of the slag-blocking cone, the ladle was agitated with argon gas at a flow rate of 500 NL / min. The final steel composition was: C=0.099%, P=0.015%, S=0.016%; the steel temperature was 1596℃.

[0128] S2, Argon Blowing Stage

[0129] After tapping, the ladle containing molten steel is transferred to the argon station, where argon gas is used to agitate the molten steel. After 30 seconds, an oxygen probe is inserted into the molten steel, and the oxygen content is quickly measured to be 15.1 ppm. 61 m of aluminum wire is fed in, with an aluminum content of 0.339 kg / m. Argon gas is blown at a flow rate of 500 NL / min for 20 seconds to ensure the aluminum wire is fully melted. A sample is taken for testing, and the aluminum content in the molten steel is 0.027%, which meets the requirements. Then, 21.9 kg of aluminum shavings and 11.9 kg of silicon carbide are added to the slag. After the addition is complete, argon gas is agitated for 40 seconds, then the argon gas is turned off, and the steel is loaded.

[0130] S3, Refining Stage

[0131] The molten steel is refined in the LF furnace and then argon is blown at a flow rate of 150 NL / min after entering the station to ensure that the slag surface is turbulent and does not form a crust; the temperature of the molten steel entering the station is 1566℃; the target temperature for the first heating stage is 1610℃, and the aluminum content of the molten steel is in the range of 0.025-0.035%.

[0132] Increase the temperature of the lower electrode;

[0133] After heating for 2 minutes, observe that the top slag has melted; add 130 kg of fluorite and 168.5 kg of quicklime into the slag, and complete the addition within 4 minutes. Then, blow argon at a high volume of 600 NL / min for 20-30 seconds to promote slag formation.

[0134] In the first two minutes of the first heating stage, 0.6 kg of silicon carbide was evenly sprayed, and the total amount of silicon carbide sprayed was 12.5 kg.

[0135] During the first heating stage, which lasts for two to six minutes, 0.5 kg of aluminum shavings are evenly sprinkled. Combined with the 22.1 kg of aluminum shavings before entering the station, the total amount of aluminum shavings sprinkled is 22.4 kg. When the slag is taken out, it is found that the slag color is too dark and does not meet the requirements for white slag. In the second heating stage, aluminum shavings need to be added for deoxidation.

[0136] In the second heating stage, the temperature was increased at 5-7℃ / min for 5 minutes, reaching 1610℃. During the second heating stage, 9 kg of aluminum shavings were evenly sprinkled, bringing the total amount of aluminum shavings sprinkled in both stages to 31.4 kg. After the molten steel reached the target temperature, the sulfur content was measured to be 0.014%, and 51 kg of silicon-manganese alloy, 29 kg of C92 carbon raiser, and 155 kg of FeTi30 type ferrotitanium were added.

[0137] After adding ferrotitanium, samples were taken to determine the composition of the molten steel: C 0.133%, Mn 0.494%, Si 0.0979%, S 0.009%, P 0.023%, Alt 0.025%, Ti 0.046%, Ca 0.0002%, T[O] 0.0015%, N 0.0032%. The final composition was then used for calculation.

[0138] (Ti)% + (Al)%+ (Ca) %-3.4 (N)%-3(S)%-(O)%

[0139] =0.046% + 0.025% + 0.0002% - 3.4 × 0.0032% - 3 × 0.009% - 0.0015%

[0140] =0.03814%≥0.03%, meets the specified requirements. The density of inclusions in the steel is 42.7 inclusions / mm². 2 .

[0141] The total heating time for the refining process was 12 minutes, the refining time was 33.8 minutes, the soft blowing time was 10 minutes, the soft blowing argon flow rate was 60 NL / min, and the outlet temperature was 1595℃.

[0142] S4, Continuous Casting Stage

[0143] Molten steel is fed into a continuous casting machine and cast into a billet; the continuous casting speed is constant at 1.20 m / min and the superheat is 33℃.

[0144] The final product composition is: C 0.132%, Mn 0.513%, Si 0.104%, S 0.007%, P 0.019%, Alt 0.026%, Ti 0.0478%, T[O] 0.0015%, N 0.0036%, which meets the composition requirements of this steel grade.

[0145] Example 3

[0146] A GF400 photovoltaic steel is smelted according to the following method:

[0147] S1, Slag Washing Stage

[0148] The molten iron in the blast furnace has an S content of 0.0195% and a P content of 0.192%, and is treated in a blast furnace.

[0149] 87.5 tons of molten iron and 16.6 tons of scrap steel were fed into the converter for smelting; the ladle was positioned, and 400 kg of quicklime and 25 kg of fluorite balls were added to it. Steel was tapped when the carbon content reached 0.053%.

[0150] During the tapping process, 80 kg of aluminum ingots, 50 kg of carburizing agent, and 598 kg of FeMn65Si17 type silicon-manganese alloy were added to the ladle. Testing revealed that the oxygen content of the molten steel in the ladle was 16.8 ppm. From the moment of tapping until the addition of the slag-blocking cone, the ladle was agitated with argon gas at a flow rate of 500 NL / min. The final steel composition was: C=0.100%, P=0.015%, S=0.016%; the steel temperature was 1599℃.

[0151] S2, Argon Blowing Stage

[0152] After tapping, the ladle containing molten steel is transferred to the argon station, where argon gas is used to agitate the molten steel. After 30 seconds, an oxygen probe is inserted into the molten steel, and the oxygen content is quickly measured to be 15.8 ppm. 62 m of aluminum wire is fed in, with an aluminum content of 0.339 kg / m. Argon is blown at a volume of 500 NL / min for 20 seconds to ensure the aluminum wire is fully melted. A sample is taken for testing, and the aluminum content in the molten steel is 0.028%, which meets the requirements. Then, 22.0 kg of aluminum shavings and 11.5 kg of silicon carbide are added to the slag. After the addition is complete, argon gas is agitated for 40 seconds, then the argon gas is turned off, and the steel is loaded.

[0153] S3, Refining Stage

[0154] The molten steel is refined in the LF furnace and argon is blown at a flow rate of 150 NL / min after entering the station to ensure that the slag surface is turbulent and does not form a crust; the temperature of the molten steel entering the station is 1562℃; the target temperature for the first heating stage is 1610℃, and the aluminum content of the molten steel is in the range of 0.025-0.035%.

[0155] Increase the temperature of the lower electrode;

[0156] After heating for 2 minutes, observe that the top slag has melted; add 129.7 kg of fluorite and 167.7 kg of quicklime into the slag, and complete the addition within 4 minutes. Then blow argon at a large volume of 600 NL / min for 20-30 seconds to promote slag formation.

[0157] In the first two minutes of the first heating stage, 1.0 kg of silicon carbide is evenly sprayed, and the total amount of silicon carbide sprayed is 12.5 kg.

[0158] During the first heating stage, which lasts for two to six minutes, 0.5 kg of aluminum shavings are evenly sprinkled, with a total sprinkled amount of 22.5 kg. When the slag is taken, it is found that the slag color is too dark and does not meet the requirements for white slag. Therefore, aluminum shavings need to be added again for deoxidation during the second heating stage.

[0159] In the second heating stage, the temperature was increased at 5-7℃ / min for 5 minutes, reaching 1610℃. During the second heating stage, 9 kg of aluminum shavings were evenly sprinkled, for a total of 31.5 kg of aluminum shavings sprinkled in both stages. After the molten steel reached the target temperature, the sulfur content of the molten steel was tested and found to be 0.009%. 50 kg of silicon-manganese alloy, 28 kg of C92 carbon raiser, and 180 kg of FeTi30 type ferrotitanium were then added.

[0160] After adding ferrotitanium, samples were taken to determine the composition of the molten steel: C 0.126%, Mn 0.528%, Si 0.131%, S 0.009%, P 0.022%, Alt 0.025%, Ti 0.052%, Ca 0.0002%, T[O] 0.0016%, N 0.0033%. The final composition was then used for calculation.

[0161] (Ti)% + (Al)%+ (Ca) %-3.4 (N)%-3(S)%-(O)%

[0162] =0.052% + 0.025% + 0.0002% - 3.4 × 0.0033% - 3 × 0.009% - 0.0016%

[0163] =0.03814%=0.0373≥0.03%, which meets the specified requirements. The density of inclusions in the steel is 38.6 inclusions / mm². 2 .

[0164] The total heating time for the refining process is 13 min, the refining time is 30.0 min, the soft blowing time is 10 min, the soft blowing argon flow rate is 60 NL / min, and the outlet temperature is 1590℃.

[0165] S4, Continuous Casting Stage

[0166] Molten steel is fed into a continuous casting machine and cast into a billet; the continuous casting speed is constant at 1.20 m / min and the superheat is 33℃.

[0167] The final product composition is: C 0.125%, Mn 0.522%, Si 0.130%, S 0.008%, P 0.021%, Alt 0.024%, Ti 0.051%, T[O] 0.0014%, N 0.0029%, which meets the composition requirements of this steel grade.

[0168] Comparative Example 1

[0169] This comparative example is basically controlled with reference to the parameters of Example 1, but there are slight differences due to the differences in the composition of molten iron and the amount of feed. The main difference is that the amount of FeTi30 type ferrotitanium added during refining is 95Kg, which results in (Ti)% + (Al)% + (Ca)% - 3.4 (N)% - 3 (S)% - (O)% < 0.03% after the addition of ferrotitanium.

[0170] A GF400 photovoltaic steel is smelted according to the following method:

[0171] S1, Slag Washing Stage

[0172] The molten iron in the blast furnace has an S content of 0.023% and a P content of 0.230%, and is treated in a blast furnace.

[0173] 86 tons of molten iron and 16.0 tons of scrap steel were fed into the converter for smelting; the ladle was positioned, and 400 kg of quicklime and 25 kg of fluorite balls were added to it. Steel was tapped when the carbon content reached 0.050%.

[0174] During the tapping process, 80 kg of aluminum ingots, 45 kg of carbon raiser, and 595 kg of FeMn65Si17 type silicon-manganese alloy were added to the ladle. Testing revealed that the oxygen content of the molten steel in the ladle was 15.9 ppm. From the moment of tapping until the addition of the slag-blocking cone, the ladle was agitated with argon gas at a flow rate of 500 NL / min. The final steel composition was: C=0.094%, P=0.022%, S=0.021%; the steel temperature was 1598℃.

[0175] S2, Argon Blowing Stage

[0176] After tapping, the ladle containing molten steel is transferred to the argon station, where argon gas is used to agitate the molten steel. After 30 seconds, an oxygen probe is inserted into the molten steel, and the oxygen content is quickly measured to be 15.3 ppm. 61 m of aluminum wire is fed in, with an aluminum content of 0.339 kg / m. Argon is blown at a volume of 500 NL / min for 20 seconds to ensure the aluminum wire is fully melted. A sample is taken for testing, and the aluminum content in the molten steel is 0.024%, which meets the requirements. Then, 20.5 kg of aluminum shavings and 11.6 kg of silicon carbide are added to the slag. After the addition is complete, argon gas is agitated for 40 seconds, then the argon gas is turned off, and the steel is loaded.

[0177] S3, Refining Stage

[0178] The molten steel is refined in the LF furnace and argon is blown at a flow rate of 150 NL / min after entering the station to ensure that the slag surface is turbulent and does not form a crust; the temperature of the molten steel entering the station is 1585℃; the target temperature for the first heating stage is 1610℃, and the aluminum content of the molten steel is in the range of 0.025-0.035%.

[0179] Increase the temperature of the lower electrode;

[0180] After heating for 2 minutes, observe that the top slag has melted; add 127 kg of fluorite and 164.2 kg of quicklime into the slag, and complete the addition within 4 minutes. Then, blow argon at a high volume of 600 NL / min for 20-30 seconds to promote slag formation.

[0181] During the first two minutes of the first heating stage, 0.9 kg of silicon carbide was evenly sprayed, and the total amount of silicon carbide sprayed was 12.5 kg.

[0182] During the first heating stage, which lasts for two to six minutes, 1.3 kg of aluminum shavings are evenly sprinkled, and the total amount of aluminum shavings sprinkled is 21.8 kg. When the slag is taken out, it is found that the slag color is too dark and does not meet the requirements for white slag. In the second heating stage, aluminum shavings need to be added to deoxidize the slag.

[0183] In the second heating stage, the temperature was increased at a rate of 5-7℃ / min for 5 minutes, reaching 1610℃. During the second heating stage, 8.8 kg of aluminum shavings were evenly sprinkled, bringing the total amount of aluminum shavings sprinkled in both stages to 30.6 kg. After the molten steel reached the target temperature, the sulfur content was measured to be 0.014%, and 50 kg of silicon-manganese alloy, 25 kg of C92 carbon raiser, and 95 kg of FeTi30 type ferrotitanium were added.

[0184] After adding ferrotitanium, samples were taken to determine the composition of the molten steel: C 0.118%, Mn 0.487%, Si 0.082%, S 0.008%, P 0.023%, Alt 0.024%, Ti 0.029%, Ca 0.0001%, T[O] 0.0016%, N 0.0033%. The final composition was then used for calculation.

[0185] (Ti)% + (Al)%+ (Ca) %-3.4 (N)%-3(S)%- (O)%

[0186] =0.029% + 0.024% + 0.0001% - 3.4 × 0.0033% - 3 × 0.008% - 0.0016%

[0187] =0.0163 < 0.03%, which does not meet the specified requirements. The density of inclusions in the steel is 38.7 inclusions / mm². 2 .

[0188] The total heating time for the refining process was 13 min, the refining time was 34.3 min, the soft blowing time was 10 min, the soft blowing argon flow rate was 60 NL / min, and the outlet temperature was 1593℃.

[0189] S4, Continuous Casting Stage

[0190] Molten steel is fed into a continuous casting machine and cast into a billet; the continuous casting speed is constant at 1.20 m / min and the superheat is 33℃.

[0191] The final product composition is: C 0.113%, Mn 0.4943%, Si 0.084%, S 0.007%, P 0.024%, Alt 0.023%, Ti 0.0278%, T[O] 0.0015%, N 0.0033%, which meets the composition requirements of this steel grade.

[0192] Comparative Example 2

[0193] This comparative example is basically controlled with reference to the parameters of Example 1, but there are slight differences due to the differences in the composition of molten iron and the amount of feed. The main difference is that the sulfur content S in the molten iron is greater than 0.025%.

[0194] A GF400 photovoltaic steel is smelted according to the following method:

[0195] S1, Slag Washing Stage

[0196] The molten iron in the blast furnace has an S content of 0.029% and a P content of 0.220%, and is treated in a blast furnace.

[0197] 85.5 tons of molten iron and 16.5 tons of scrap steel were fed into the converter for smelting; the ladle was positioned, and 400 kg of quicklime and 25 kg of fluorite balls were added to it. Steel was tapped when the carbon content reached 0.051%.

[0198] During the tapping process, 80 kg of aluminum ingots, 45 kg of carbon raiser, and 590 kg of FeMn65Si17 type silicon-manganese alloy were added to the ladle. Testing revealed that the oxygen content of the molten steel in the ladle was 16.9 ppm. From the moment of tapping until the addition of the slag-blocking cone, the ladle was agitated with argon gas at a flow rate of 500 NL / min. The final steel composition was: C=0.095%, P=0.022%, S=0.026%; the steel temperature was 1599℃.

[0199] S2, Argon Blowing Stage

[0200] After tapping, the ladle containing molten steel is transferred to the argon station, where argon gas is used to agitate the molten steel. After 30 seconds, an oxygen probe is inserted into the molten steel, and the oxygen content is quickly measured to be 16.4 ppm. 60 m of aluminum wire is fed in, with an aluminum content of 0.339 kg / m. Argon is blown at a volume of 500 NL / min for 20 seconds to ensure the aluminum wire is fully melted. A sample is taken for testing, and the aluminum content in the molten steel is 0.023%, which meets the requirements. Then, 21.0 kg of aluminum shavings and 11.0 kg of silicon carbide are added to the slag. After the addition is complete, argon gas is agitated for 40 seconds, then the argon gas is turned off, and the steel is loaded.

[0201] S3, Refining Stage

[0202] The molten steel is refined in the LF furnace and argon is blown at a flow rate of 150 NL / min after entering the station to ensure that the slag surface is turbulent and does not form a crust; the temperature of the molten steel entering the station is 1583℃; the target temperature for the first heating stage is 1610℃, and the aluminum content of the molten steel is in the range of 0.025-0.035%.

[0203] Increase the temperature of the lower electrode;

[0204] After heating for 2 minutes, observe that the top slag has melted; add 127 kg of fluorite and 165 kg of quicklime into the slag, and complete the addition within 4 minutes. Then, blow argon at a high volume of 600 NL / min for 20-30 seconds to promote slag formation.

[0205] During the first two minutes of the first heating stage, 1.5 kg of silicon carbide was evenly sprayed, and the total amount of silicon carbide sprayed was 12.5 kg.

[0206] During the first heating stage, which lasts for two to six minutes, 0.8 kg of aluminum shavings are evenly sprinkled, and the total amount of aluminum shavings sprinkled is 21.8 kg. When the slag is taken out, it is found that the slag color is too dark and does not meet the requirements for white slag. Therefore, aluminum shavings need to be added again for deoxidation during the second heating stage.

[0207] In the second heating stage, the temperature was increased at a rate of 5-7℃ / min for 5 minutes, reaching 1610℃. During the second heating stage, 9.0 kg of aluminum shavings were evenly sprinkled, bringing the total amount of aluminum shavings sprinkled in both stages to 30.8 kg. After the molten steel reached the target temperature, the sulfur content was measured to be 0.026%, and 50 kg of silicon-manganese alloy, 25 kg of C92 carbon raiser, and 150 kg of FeTi30 type ferrotitanium were added.

[0208] After adding ferrotitanium, samples were taken to determine the composition of the molten steel: C 0.119%, Mn 0.490%, Si 0.090%, S 0.012%, P 0.021%, Alt 0.023%, Ti 0.046%, Ca 0.0001%, T[O] 0.0019%, N 0.0032%. The final composition was then used in calculations.

[0209] (Ti)% + (Al)%+ (Ca) %-3.4 (N)%-3(S)%- (O)%

[0210] =0.046% + 0.023% + 0.0001% - 3.4 × 0.0032% - 3 × 0.012% - 0.0019%

[0211] 0.0203 < 0.03%, which does not meet the specified requirements. The density of inclusions in the steel is 48.6 inclusions / mm². 2 .

[0212] The total heating time for the refining process was 12 minutes, the refining time was 32.5 minutes, the soft blowing time was 10 minutes, the soft blowing argon flow rate was 60 NL / min, and the outlet temperature was 1594℃.

[0213] S4, Continuous Casting Stage

[0214] Molten steel is fed into a continuous casting machine and cast into a billet; the continuous casting speed is constant at 1.20 m / min and the superheat is 33℃.

[0215] The final product composition is: C 0.116%, Mn 0.494%, Si 0.091%, S 0.011%, P 0.021%, Alt 0.022%, Ti 0.045%, T[O] 0.0018%, N 0.0032%, which meets the composition requirements of this steel grade.

[0216] The mechanical properties of GF400 photovoltaic steel prepared in Examples 1-3 and Comparative Examples 1-2 were tested. The test methods are as follows: GB / T 228.1-2021 Metallic materials, tensile testing—Part 1: Tests at room temperature. The test data are as follows:

[0217] Yield strength (MPa) Tensile strength (MPa) Elongation after fracture (%) Cold bending (d=2a) Example 1 473 535 28.7 qualified Example 2 466 528 27.8 qualified Example 3 469 542 26.5 qualified Comparative Example 1 358 485 25.1 Unqualified Comparative Example 2 365 477 25.7 qualified

[0218] Metallographic analysis was performed on the steel samples prepared in Examples 1 to 3 and Comparative Examples 1 to 2 (using a Leica DMI3000M metallographic microscope), and the samples were rated according to the relevant requirements of GB / T 10561-2023 Standard Rating Chart Microscopic Examination Method for Determination of Non-metallic Inclusion Content in Steel.

[0219] organize Grain size Inclusions Example 1 F+P 11.5 <![CDATA[AT1.5,AH0,BT0,BH0,CT0,CH0,DT1.0,DH0.5,DS0,D TiN 0.5]]> Example 2 F+P 11.9 <![CDATA[AT1.5,AH0,BT0,BH0,CT0,CH0,DT1.5,DH1.0,DS0,D TiN 1.0]]> Example 3 F+P 11.5 <![CDATA[AT1.5,AH0,BT0,BH0,CT0,CH0,DT1.0,DH0.5,DS0,D TiN 0.5]]> Comparative Example 1 F+P 8.5 <![CDATA[AT1.5,AH0,BT0,BH0,CT0,CH0,DT1.0,DH0.5,D TiN 0.5,DS2.0]]> Comparative Example 2 F+P 11.7 <![CDATA[AT2.5,AH0,BT0,BH0,CT0,CH0,DT1.5,DH1.0,DS0,D TiN 1.0, sulfide segregation regions form ferrite bands.

[0220] As can be seen from the above data, the steels of Examples 1 to 3 of the present invention using the method of the present invention have a yield strength of over 460 MPa and a tensile strength of over 520 MPa. Both the yield strength and tensile strength are significantly better than those of the comparative examples. Their elongation after fracture and cold bending can meet the requirements for photovoltaic steel. At the same time, the number of inclusions is small and the particle size is small. The metallographic structure is uniform and the grain size is fine.

[0221] The steels smelted by the methods of Comparative Examples 1 and 2 all showed different performance characteristics compared to the products of the examples. Comparative Example 1 had insufficient Ti content, a grain-refining element, resulting in coarse grains and slightly poorer mechanical properties. Comparative Example 2 used high-sulfur molten iron, resulting in a higher S content in the final molten steel. The precipitated sulfide inclusions disrupted the continuity of the steel matrix, causing stress concentration and reducing the mechanical properties of the steel.

[0222] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A highly efficient and precise smelting method for GF400 photovoltaic steel, characterized in that... Includes the following steps: S1, Slag Washing Stage When the molten steel in the converter is blown to a carbon content of 0.05% to 0.08%, it is tapped. Lime and fluorite are added to the ladle to adjust the slag. When tapping, carbonizing agent, aluminum ingots and silicon-manganese alloy are added to the ladle to deoxidize and adjust the composition of the molten steel, and reduce the oxygen content in the molten steel to below 20 ppm. S2, Argon Blowing Stage After tapping, the ladle is moved to the argon station and bottom-blown with argon for 30 seconds. The oxygen content in the steel is then measured. Based on the measured oxygen content, aluminum wire is replenished in one go. After feeding the wire, the total aluminum content in the steel is controlled at 0.020%-0.030%, and then it is sent to the LF furnace. S3, Refining Stage The LF refining temperature of the molten steel is controlled at 1610℃-1620℃. Lime and fluorite are added to form slag and remove inclusions. The composition of the molten steel is adjusted by adding silicon-manganese alloy, carbon raiser and ferrotitan. S4, Continuous Casting Stage Molten steel is fed into a continuous casting machine and cast into a billet; the continuous casting speed is constant and controlled at 1.10-1.20 m / min.

2. The efficient and precise smelting method for GF400 photovoltaic steel according to claim 1, characterized in that: In step S1, the sulfur content in the molten iron used for smelting is controlled to be S≤0.025%, and the silicon-manganese alloy added during tapping is FeMn65Si17 type silicon-manganese alloy, and the carbon raiser is C92 carbon raiser.

3. The efficient and precise smelting method for GF400 photovoltaic steel according to claim 2, characterized in that: In step S1, the amount of aluminum ingots added is 0.72-0.93 kg / t, and conforms to the following calculation formula: ； In the formula: η The aluminum recovery rate during converter tapping is approximately 30%-45%. M Aluminum ingot addition amount, Kg / t; W 0: Oxygen content at the time of tapping from the converter, in ppm; Wt Final oxygen content, ppm.

4. The efficient and precise smelting method for GF400 photovoltaic steel according to claim 1, characterized in that: In step S2, when steel is fed into the LF furnace, the argon blowing station must prepare aluminum granules / aluminum chips and silicon carbide, and evenly sprinkle aluminum chips / aluminum granules and silicon carbide on the slag surface of the molten steel. After stirring and slag formation, the argon gas is turned off.

5. The efficient and precise smelting method for GF400 photovoltaic steel according to claim 1, characterized in that... Step S3 includes two heating stages: S31, First heating stage The target steel temperature for the first heating stage is 1600℃-1610℃. The steel temperature is controlled by adjusting the electrode current, with a heating rate of 4℃ / min-7℃ / min, to ensure that the steel temperature reaches 1600℃-1610℃ by the 10th minute. For the first two minutes of the first heating stage, silicon carbide is evenly sprinkled into the molten steel; after heating for 2 minutes, observe whether the top slag has melted. After the top slag has melted, add 1.72 kg / t of lime and 1.33 kg / t of fluorite into the molten steel; in addition, during the first heating stage from 2 to 6 minutes, aluminum shavings are evenly sprinkled until the heating is over. After the aluminum shavings are added in the first heating stage, observe the slag. If the slag is black, it means that the deoxidation is not up to standard, and aluminum shavings still need to be added in the second heating stage. If the slag is white or grayish-white, it means that the deoxidation is up to standard, and aluminum shavings do not need to be added in the second heating stage. Temperature measurement and sampling are performed at the 10th minute. If the sulfur content in the molten steel exceeds 0.014%, continue blowing argon at a large volume of 400-700 NL / min for two minutes before entering the second heating stage. If the sulfur content in the molten steel is less than 0.014%, proceed directly to the next heating stage. S32, Second heating stage The target temperature of the molten steel in the second heating stage is 1610℃-1620℃. The temperature rise of the molten steel is controlled by controlling the electrode current, with the heating rate in the range of 5℃ / min-7℃ / min, to ensure that the target heating temperature of the molten steel is reached within the first 5 minutes of the second heating stage. After the molten steel reaches the target temperature, a sample of the molten steel slag is taken for analysis. If the slag adhesion is found to be unqualified during the first heating stage, aluminum chips are evenly sprinkled for deoxidation during the second heating stage. After the slag adhesion is qualified, 1.5-2.0 Kg / t of FeTi30 type ferrotitanium is added to the molten steel and gently blown for 10-15 min.

6. The efficient and precise smelting method for GF400 photovoltaic steel according to claim 5, characterized in that: In the refining step, the refining time is greater than 30 min, and the white slag time is greater than 10 min; the total amount of aluminum shavings sprinkled in the two heating stages is 0.1 kg / t; the flow rate of soft blowing argon is controlled within the range of 20 to 60 NL / min.

7. The efficient and precise smelting method for GF400 photovoltaic steel according to claim 6, characterized in that: After adding ferrotitanium, the mass percentage of titanium in the molten steel is limited to (Ti)% + (Al)% + (Ca)% - 3.4 (N)% - 3 (S)% - (O)% ≥ 0.03%.

8. The efficient and precise smelting method for GF400 photovoltaic steel according to claim 7, characterized in that: After refining, the final composition of the molten steel is: C 0.10-0.14%, Si 0.08-0.12%, Mn 0.45-0.55%, S≤0.015%, P≤0.025%, Alt 0.020-0.025%, Ti≥0.040%, T[O]≤0.0020%, N%≤0.0040%.

Images