Method for improving detection precision of aluminum content in molten steel

Abstract

The invention relates to a method for improving molten steel aluminum content detection precision, and belongs to the technical field of molten steel aluminum content detection.The method comprises the following steps that converter tapping silicon carbide is subjected to pre-deoxidation; and adding ferrosilicon for alloying, and adding an aluminum block for deoxidizing and refining. During deoxidation refining, the basicity of the slag is controlled to be 0.5-0.6, the white slag atmosphere is kept for more than 10 minutes, 0.5-1.5 kg / t of bauxite and 0.5-1.0 kg / t of magnesia are added during refining outbound, the content of aluminum oxide and MgO in the slag is increased, and the content of TFe + MnO in the outbound slag is controlled to be smaller than or equal to 2%. A pail sampler with the specification of 40mm * 120mm is selected to sample molten steel, and the depth of the pail sampler inserted into the molten steel is controlled to be 230-250mm. After sampling, uniformly cooling the pail sampler in a 20-DEG C cooling device to obtain a sample A; the method realizes accurate control of aluminum in molten steel, meets the quality requirements of products, and has the characteristics of high detection precision, good detection effect and high sample aluminum content uniformity, thereby improving the performance of the products.

Description

Technical Field

[0001] The invention belongs to the technical field of molten steel aluminum content detection, and specifically relates to a method for improving the detection accuracy of molten steel aluminum content. Background Art

[0002] The detection fluctuation of aluminum in slab steel is relatively large. For some steel grades, the amount of aluminum nitride precipitation needs to be controlled. It is required to further improve the detection accuracy of aluminum in molten steel and achieve precise control of aluminum in molten steel, thereby improving product performance.

[0003] At present, when using a pancake sampler to sample molten steel, the pancake sample undergoes secondary oxidation during the sampling process, resulting in a low aluminum content, which can easily lead to uneven samples, shrinkage cavities, and inaccurate cooling rate control. The samples are directly thrown into the water tank for cooling, and the cooling rate varies greatly, especially in winter. If the temperature is low, the samples are prone to cracks, resulting in a high total oxygen measurement. In addition, the pancake sample has a small sample size, and it is difficult to avoid the central porous shrinkage layer when cutting, which also leads to a large standard deviation of aluminum detection.

[0004] The detection accuracy of the traditional pancake sampler is relatively poor, with large fluctuations and a standard deviation of 0.0010% (the requirement for aluminum in molten steel is 0.032%), which is difficult to meet the quality requirements of the product. Therefore, a method for improving the detection accuracy of aluminum content in molten steel is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a method for improving the detection accuracy of aluminum content in molten steel with a reasonable design in order to solve the above-mentioned problem.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] The present invention provides a method for improving the detection accuracy of aluminum content in molten steel, comprising the following steps:

[0008] Deoxidation and refining of molten steel: first pre-deoxidize the silicon carbide out of the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0009] Molten steel sampling: Use a bucket sampler to sample the molten steel. The depth of the bucket sampler inserted into the molten steel should be controlled between 230-250mm.

[0010] After sampling, place the bucket sampler in a 20° cooling device to cool evenly to obtain sample A;

[0011] Cutting test: Send sample A to the cutting machine for cutting, and select the position 20mm away from the end of the sample to cut, and obtain sample B;

[0012] Then, the sample B is firstly subjected to milling by a milling machine. After the milling by the milling machine, the grinding depth of the sample B is controlled to be 1.2 mm;

[0013] Sample B was polished with 800-mesh silicon carbide sandpaper to a roughness of 0.8 μm, and then the aluminum content was measured after being cleaned with alcohol and cooled.

[0014] During deoxidation refining, the slag basicity is controlled between 0.5 and 0.6, and the white slag atmosphere is maintained for more than 10 minutes;

[0015] Add bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t at the refining station, control the basicity of ladle slag to 0.5-0.6, the alumina content in the slag to 20-30%, the MgO in the slag to 10-20%, and TFe+MnO in the slag ≤2%.

[0016] Among them, the diameter of the bucket sampler is 40mm and the height is 120mm.

[0017] When sampling, the bucket sampler stays in the molten steel for 6-10 seconds.

[0018] Among them, the cooling time is 3 minutes.

[0019] The roughness is measured by one of the following testing devices: an interference microscope, a stylus surface roughness meter, and a light-section microscope, and the grinding time with 800-grit silicon carbide sandpaper is 2 minutes.

[0020] Among them, the determination method of aluminum content is:

[0021] Six detection points are obtained on sample B, and the detection values ​​SD are obtained for the six detection points respectively. The beneficial effect of the present invention is that the precision detection method adopted by the present invention realizes the precise control of the aluminum content in molten steel, ensuring that the product meets the high quality standard. The method is characterized by high detection accuracy, excellent detection effect and high uniformity of aluminum content in the sample, which significantly improves the comprehensive performance of the product. At the same time, by adopting a bucket sampler, not only the sufficient amount of samples is ensured, but also the subsequent processing of samples is greatly facilitated. DETAILED DESCRIPTION

[0022] The present application is described in further detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0023] In order to verify the effect of the present invention, the following experiments were carried out on the embodiments and comparative examples:

[0024] Example 1

[0025] A method for improving the detection accuracy of aluminum content in molten steel comprises the following steps:

[0026] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0027] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0028] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0029] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0030] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0031] (2) Molten steel sampling: Select a bucket sampler with a specification of 40mm*120mm for molten steel sampling, and control the depth of the bucket sampler inserted into the molten steel to be 230mm.

[0032] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds. This can increase the sample saturation and reduce the occurrence of shrinkage holes and looseness in the sample.

[0033] After sampling, place the bucket sampler in a 20° cooling pool for uniform cooling for 3 minutes. This ensures that the sample does not have microcracks due to excessive cooling, which would result in high oxygen measurement.

[0034] After cooling, sample A was obtained;

[0035] (3) Cutting test: a. Send sample A from step (2) to a cutting machine for cutting, and select a position 20 mm away from the end of the sample for cutting.

[0036] After cutting off the sample A, the sample B is obtained; and then the sample B is milled by a milling machine, the grinding depth of the sample B is 1.2mm, and the sample B has no shrinkage holes visible to the naked eye;

[0037] b. After processing, sample B is polished with 800-mesh silicon carbide sandpaper for 2 minutes, and then the roughness of the sample processing surface is tested using one of the testing devices selected from an interference microscope, a stylus surface roughness measuring instrument, and a light sectioning microscope. This embodiment takes an interference microscope as an example.

[0038] After the cutting surface of sample B is processed, the roughness is 0.7um. Sample B is then cleaned and cooled with alcohol to reduce its heat generation and oxidation. Finally, the aluminum content is measured in 3 minutes after it evaporates.

[0039] Final data results: The aluminum content of 6 points on sample B was tested, and the SD of the test value at each point was 0.00021%.

[0040] It should be noted that during the sample preparation process, the sample cannot turn yellow. Because the sample is rough, the surface is easily oxidized, and the oxygen content is high, the aluminum content of the test sample is lower than the actual value of the molten steel, and the fluctuation is relatively large. In addition, it should be noted again that the aluminum content on the test sample B can be selected from: optical emission spectroscopy, laser induced breakdown spectroscopy (LIBS) technology, and data acquisition and analysis. This embodiment takes optical emission spectroscopy as an example, and the detection process is omitted.

[0041] Example 2

[0042] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0043] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0044] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0045] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0046] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0047] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 235 mm.

[0048] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0049] After sampling, the bucket sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0050] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0051] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.8 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured 3 minutes later.

[0052] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00022%.

[0053] Example 3

[0054] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0055] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0056] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0057] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0058] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0059] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 240 mm.

[0060] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0061] After sampling, the bucket sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0062] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0063] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.6 μm after processing, and it was cleaned with alcohol, and the aluminum content was measured 3 minutes after it evaporated.

[0064] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00020%.

[0065] Example 4

[0066] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0067] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0068] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0069] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0070] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0071] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 245 mm.

[0072] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0073] After sampling, the bucket sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0074] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0075] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.7 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured for 3 minutes.

[0076] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00024%.

[0077] Example 5

[0078] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0079] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0080] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0081] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0082] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0083] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 250 mm.

[0084] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0085] After sampling, the bucket sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0086] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0087] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.8 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured 3 minutes later.

[0088] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00023%.

[0089] Comparative Example 1

[0090] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0091] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0092] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0093] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0094] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0095] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 235 mm.

[0096] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0097] After sampling, the bucket sampler was placed in a common cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0098] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0099] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.5 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured 3 minutes later.

[0100] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00092%.

[0101] Comparative Example 2

[0102] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0103] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0104] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0105] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0106] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0107] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 240 mm.

[0108] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0109] After sampling, the bucket sampler was placed in a common cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0110] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0111] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.7 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured for 3 minutes.

[0112] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00089%.

[0113] Comparative Example 3

[0114] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0115] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0116] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0117] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0118] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0119] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 245 mm.

[0120] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0121] After sampling, the bucket sampler was placed in a common cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0122] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0123] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.5 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured 3 minutes later.

[0124] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00092%.

[0125] Comparative Example 4

[0126] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0127] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0128] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0129] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0130] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0131] (2) Molten steel sampling: Use a pancake sampler to sample the molten steel. The pancake sampler is inserted into the molten steel to a depth of 230 mm.

[0132] When sampling, let the cake sampler stay in the molten steel for 6-10 seconds;

[0133] After sampling, the cake sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0134] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0135] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.7 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured for 3 minutes.

[0136] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00089%.

[0137] Comparative Example 5

[0138] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0139] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0140] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0141] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0142] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0143] (2) Molten steel sampling: Use a pancake sampler to sample the molten steel. The pancake sampler is inserted into the molten steel to a depth of 240 mm.

[0144] When sampling, let the cake sampler stay in the molten steel for 6-10 seconds;

[0145] After sampling, the cake sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0146] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0147] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.7 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured for 3 minutes.

[0148] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00087%.

[0149] Comparative Example 6

[0150] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0151] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0152] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0153] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0154] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0155] (2) Molten steel sampling: A pancake sampler is used to sample the molten steel. The pancake sampler is inserted into the molten steel to a depth of 250 mm.

[0156] When sampling, let the cake sampler stay in the molten steel for 6-10 seconds;

[0157] After sampling, the cake sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0158] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0159] Sample B was polished with 800-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 0.8 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured 3 minutes later.

[0160] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00088%.

[0161] Comparative Example 7

[0162] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0163] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0164] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0165] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0166] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0167] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 230 mm.

[0168] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0169] After sampling, the bucket sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0170] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0171] Sample B was polished with 360-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 3.8 μm after processing. It was cleaned with alcohol and the aluminum content was measured after 3 minutes of evaporation.

[0172] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00141%.

[0173] Comparative Example 8

[0174] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0175] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0176] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0177] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0178] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0179] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 240 mm.

[0180] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0181] After sampling, the bucket sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0182] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0183] Sample B was polished with 480-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 2.2 μm after processing. It was cleaned with alcohol and the aluminum content was measured after 3 minutes of evaporation.

[0184] The aluminum content of 6 points on sample B was tested, and the SD of each point test value was 0.00102%

[0185] Comparative Example 9

[0186] (1) Deoxidation and refining of molten steel: First, pre-deoxidize the silicon carbide produced from the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining;

[0187] During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes. Bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t are added at the refining station. The ladle slag basicity is controlled at 0.5-0.6, the alumina content in the slag is 20-30%, the MgO in the slag is 10-20%, and the TFe+MnO in the slag is ≤2%.

[0188] Among them, the slag is acidic slag with high viscosity and thick slag, which can reduce the reaction of steel slag, thereby stabilizing the aluminum content in molten steel, increasing the content of alumina and MgO in the slag, and also increasing the viscosity of the slag.

[0189] Then the free oxygen content is measured and the aluminum addition operation is performed, specifically:

[0190] The free oxygen content in the molten steel in step (1) is measured using an oxygen meter, and aluminum wire is added to increase aluminum, the ratio of acid-soluble aluminum to total aluminum is controlled to be above 92%, and the aluminum content is controlled to be between 0.015% and 0.025%;

[0191] (2) Molten steel sampling: A bucket sampler with a specification of 40 mm*120 mm is selected for molten steel sampling. The bucket sampler is inserted into the molten steel to a depth of 240 mm.

[0192] When sampling, let the bucket sampler stay in the molten steel for 6-10 seconds;

[0193] After sampling, the bucket sampler was placed in a 20° cooling pool for uniform cooling for 3 minutes to obtain sample A.

[0194] The sample A in step (2) is sent to a cutting machine for cutting, and the cutting is performed at a position 20 mm away from the end of the sample. After the sample A is cut, the obtained sample B is milled by a milling machine. The grinding depth of the sample B is 1.2 mm, and there is no shrinkage cavity visible to the naked eye in the sample B.

[0195] Sample B was polished with 600-grit silicon carbide sandpaper for 2 minutes. The roughness of the cut surface of sample B was 1.2 μm after processing, and it was cleaned with alcohol. After evaporation, the aluminum content was measured 3 minutes later.

[0196] The aluminum content of 6 points on sample B was detected, and the SD of the detection value at each point was 0.00081%.

[0197] The test samples B obtained from the above Examples 1-5 and Comparative Examples 1-9 were tested respectively, and the aluminum content at 6 points on the test sample B was tested. The results are summarized in the following table:

[0198]

[0199] From the above data, it is obvious that the standard deviation of aluminum content in the cake sample is greater than that in the bucket sample, indicating that the alumina distribution of the former is uneven; the oxygen content analysis result of the cake sample is high, and the uniformity of aluminum content in the sample is poor. Therefore, the precision detection method adopted in the present invention realizes the precise control of aluminum content in molten steel and ensures that the product meets high quality standards. This method is characterized by high detection accuracy, excellent detection effect and high uniformity of aluminum content in the sample, which significantly improves the comprehensive performance of the product. At the same time, by adopting a bucket sampler, not only the sufficient amount of sample is ensured, but also the subsequent processing of the sample is greatly facilitated.

[0200] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for improving the detection accuracy of aluminum content in molten steel, characterized in that: The steps include: Deoxidation and refining of molten steel: first pre-deoxidize the silicon carbide out of the converter; then add ferrosilicon for alloying, and then add aluminum blocks for deoxidation and refining; Molten steel sampling: Use a bucket sampler to sample the molten steel. The depth of the bucket sampler inserted into the molten steel should be controlled between 230-250mm. After sampling, place the bucket sampler in a 20° cooling device to cool evenly to obtain sample A; Cutting test: Send sample A to the cutting machine for cutting, and select the position 20mm away from the end of the sample to cut, and obtain sample B; Then, the sample B is firstly subjected to milling by a milling machine. After the milling by the milling machine, the grinding depth of the sample B is controlled to be 1.2 mm; Sample B was polished with 800-mesh silicon carbide sandpaper to a roughness of 0.5-0.8 um, and the aluminum content was measured after cleaning with alcohol and cooling.

2. A method for improving the detection accuracy of aluminum content in molten steel according to claim 1, characterized in that: During deoxidation refining, the slag basicity is controlled between 0.5-0.6, and the white slag atmosphere is maintained for more than 10 minutes; Add bauxite 0.5-1.5kg / t and magnesia 0.5-1.0kg / t at the refining station, control the basicity of ladle slag to 0.5-0.6, the alumina content in the slag to 20-30%, the MgO in the slag to 10-20%, and TFe+MnO in the slag ≤2%.

3. A method for improving the detection accuracy of aluminum content in molten steel according to claim 1, characterized in that: The diameter of the bucket sampler is 40mm and the height is 120mm.

4. A method for improving the detection accuracy of aluminum content in molten steel according to claim 3, characterized in that: When sampling, the bucket sampler stays in the molten steel for 6-10 seconds.

5. The method for improving the detection accuracy of aluminum content in molten steel according to claim 1, characterized in that: The cooling time is 3 minutes.

6. A method for improving the detection accuracy of aluminum content in molten steel according to claim 1, characterized in that: The roughness is measured by one of the testing devices including an interference microscope, a stylus surface roughness meter and a light section microscope, and the grinding time is 2 minutes with 800-grit silicon carbide sandpaper.

7. The method for improving the detection accuracy of aluminum content in molten steel according to claim 1, characterized in that: The aluminum content is measured by: Six detection points are obtained on sample B, and detection values ​​SD are obtained for each of the six detection points.

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