A spectral standard for non-oriented silicon steel and its preparation method

Abstract

The present invention discloses a method for preparing a non-oriented silicon steel spectral standard sample, comprising: smelting a cast billet according to a designed chemical composition; hot cutting the cast billet to obtain a square billet; cooling the square billet step by step; cutting the cooled square billet by a quartering method to prepare a test sample and a finished square billet; performing an element segregation test and a physical macrostructure test on the test sample, and preparing a spectral standard sample from the finished square billet according to the test result; and determining the chemical elements including the oxygen content of the spectral standard sample after the structure test and the uniformity test. The present invention also discloses a non-oriented silicon steel spectral standard sample. The present invention ensures that the internal structure of a high-grade non-oriented silicon steel spectral sample with high silicon, high aluminum, and low gas elements of carbon, sulfur, nitrogen, and oxygen is free of cracks and defects. Under the premise of meeting uniformity and consistency, the research and development batch is expanded to meet the requirements of good uniformity and large quantity of pre-furnace spectral control samples under an automated intelligent analysis system.

Description

Technical Field

[0001] The invention relates to the field of chemical analysis of metallurgical samples, and in particular to a non-oriented silicon steel spectrum standard sample and a preparation method thereof. Background Art

[0002] Silicon steel refers to a low-carbon ferrosilicon alloy with a silicon content of 0.5% to 4.5%. It was once known as the "craft among steel products". Due to its different structures and uses, it is divided into non-oriented silicon steel and oriented silicon steel. Silicon steel is mainly used as the core of various motors, generators, compressors, motors and transformers. It is an indispensable raw material product in the power, home appliance and other industries.

[0003] In recent years, the production capacity of silicon steel has grown rapidly. Therefore, the demand for silicon steel standard samples in the process of testing the chemical composition of materials by various silicon steel production and use companies has increased year by year. At present, the lack of silicon steel spectral standard samples has restricted the application of its rapid and accurate spectral analysis.

[0004] Silicon steel is divided into two categories: non-oriented silicon steel and oriented silicon steel. Non-oriented silicon steel is further divided into many grades, among which non-oriented silicon steel with high aluminum, high silicon and low gas content belongs to high-grade and high-performance non-oriented silicon steel products.

[0005] For high-grade non-oriented silicon steel with high aluminum, high silicon and low gas content, the aluminum and silicon content of the non-oriented silicon steel is very high, with a high aluminum content of 1.0-1.2% and a high silicon content of 3.0-3.5%. The content of gas elements carbon, sulfur, nitrogen and oxygen is extremely low, C <30ppm (0.0030%), S, N, O content <10ppm (0.0010%). Due to the presence of high silicon, high aluminum, and low gas elements carbon, sulfur, nitrogen and oxygen, it is a high-grade product among non-oriented silicon steel products, mainly used in high-end markets and high-end users. The high-grade non-oriented silicon steel has a low thermal conductivity, and is difficult to smelt and heat process. When the sample is heated and cooled, the internal and external cooling speeds are inconsistent, and internal structural defects and cracking such as structural cracks are very likely to occur.

[0006] Traditionally, the spectral standard samples of silicon steel are prepared by sampling from continuous casting billets, usually through direct forging or ordinary heat preservation. If this technology is applied to high-grade non-oriented silicon steel with high silicon, high aluminum, and low gas elements carbon, sulfur, nitrogen, and oxygen, the obtained samples will have the disadvantages of internal tissue cracking, poor physical properties, and poor uniformity. Summary of the invention

[0007] In view of the above problems, an object of the present invention is to provide a non-oriented silicon steel spectrum standard sample and a method for preparing the same.

[0008] In one aspect, the present invention provides a method for preparing a non-oriented silicon steel spectral standard sample, comprising:

[0009] Step S1, smelting the ingot according to the designed chemical composition;

[0010] Step S2, hot cutting the ingot to obtain a square billet;

[0011] Step S3, cooling the billet step by step;

[0012] Step S4, cutting the cooled billet by a quartering method to obtain test samples and finished billets;

[0013] Step S5, performing element segregation inspection and physical macrostructure inspection on the inspection sample, and preparing a spectral standard sample from the finished square billet according to the inspection results;

[0014] Step S6, the spectral standard sample is subjected to structural inspection and uniformity test, and then chemical elements including oxygen content are determined.

[0015] On the other hand, the present invention also provides a non-oriented silicon steel spectrum standard sample obtained by the above-mentioned preparation method.

[0016] Compared with the prior art, the non-oriented silicon steel spectrum standard sample and the preparation method thereof of the present invention have at least the following beneficial effects:

[0017] The non-oriented silicon steel spectral standard sample and its preparation method of the present invention ensure that the internal structure of the high-grade non-oriented silicon steel spectral sample with high silicon, high aluminum and low gas elements carbon, sulfur, nitrogen and oxygen is free of cracks and defects. Under the premise of meeting uniformity and consistency, the research and development batch is expanded to meet the requirements of good uniformity and large quantity of pre-furnace spectral control samples under the automated intelligent analysis system. The fixed value of the oxygen element provides a physical standard for direct reading spectral analysis of the oxygen element, providing a new technical idea for direct reading spectral analysis of the oxygen element. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0019] Figure 1 The present invention is a process flow chart of the method for preparing the non-oriented silicon steel spectrum standard sample.

[0020] Figure 2 The figure shows the cutting method of the ingot in Example 1 of the present invention, and the dotted line in the figure indicates the cutting position.

[0021] Figure 3The figure shows the cutting method of obtaining long film 1 and long film 2 by the quartering method in Example 1 of the present invention, and the dotted lines in the figure indicate the cutting positions.

[0022] Figure 4 The figure shows the cutting method of obtaining wide sheet 1 and wide sheet 2 by the quartering method in Example 1 of the present invention, and the dotted lines in the figure indicate the cutting positions.

[0023] Figure 5 The figure shows the cutting method of the finished billet obtained by the quartering method in Example 1 of the present invention, and the dotted line in the figure indicates the cutting position.

[0024] Figure 6 The method of selecting analysis points for long film 1 in embodiment 1 of the present invention is shown.

[0025] Figure 7 The method of selecting analysis points for the long film 2 in the embodiment 1 of the present invention is shown.

[0026] Figure 8 The method of selecting analysis points for the wide sheet 1 in embodiment 1 of the present invention is shown. DETAILED DESCRIPTION

[0027] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments. Except for the following contents, the process method of the present invention adopts conventional methods or devices in the art. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0028] The present invention specifically develops a method for making a spectral standard sample for high-grade non-oriented silicon steel. The so-called high-grade non-oriented silicon steel mainly refers to a steel with very high aluminum and silicon contents, with a high aluminum content of 1.0-1.2% and a high silicon content of 3.0-3.5%, and extremely low contents of gaseous elements carbon, sulfur, nitrogen and oxygen, with C <30ppm (0.0030%), and S, N and O contents <10ppm (0.0010%) respectively. Since high silicon, high aluminum and low gaseous elements carbon, sulfur, nitrogen and oxygen exist at the same time, it belongs to a high-grade product among non-oriented silicon steel products.

[0029] Combine the following Figure 1 , the method for preparing the non-oriented silicon steel spectral standard sample of the present invention is described in detail.

[0030] The method for preparing a non-oriented silicon steel spectrum standard sample of the present invention comprises:

[0031] Step S1: smelting the ingot according to the designed chemical composition.

[0032] When designing the chemical composition, the requirements for the chemical composition are that the aluminum content is greater than 1.00%, the silicon content is greater than 3.00%, the carbon content is less than 0.0030%, the sulfur content is less than 0.0010%, the nitrogen content is less than 0.0010%, and the oxygen content is less than 0.0010%.

[0033] Based on the above requirements, in the present invention, the chemical composition is designed to be, by weight percentage, Al 1.00% to 1.20%, Si 3.00% to 3.50%, C≤0.0030%, S≤0.0010%, N≤0.0010%, O≤0.0010%, Mn≤0.35%, P≤0.015%, Cr≤0.020%, Ni≤0.010%, Cu≤0.0050%, Ti≤0.0040%, and the remainder is iron and unavoidable impurity elements.

[0034] According to the chemical composition designed above, the ingot is smelted. In the present invention, the smelting can be carried out by conventional methods in the art. For example, raw materials with low impurity content are selected, component proportioning is carried out, hot metal desulfurization, converter smelting, vacuum refining outside the furnace, and continuous casting are carried out. It is ensured that the smelted high-grade non-oriented silicon steel has extremely low content of harmful gas elements. Of course, this is only exemplary, and those skilled in the art can also choose other conventional smelting methods according to production needs, as long as the ingot with the required chemical composition can be obtained.

[0035] Step S2: hot cutting the ingot to obtain a square billet.

[0036] Take a fixed width (usually 1000-1600mm) of the ingot for hot cutting.

[0037] The so-called thermal cutting means ensuring that the temperature of the billet is between 700 and 900°C during cutting. Thermal cutting specifically includes: taking the continuous casting direction as the length direction, the fixed width of the billet is usually 1000 to 1600 mm, and the height direction is usually 180 to 300 mm. Oxygen welding cutting takes a length of 300 to 500 mm in the length direction. And in the middle of the width direction and 1 / 4 near the edge, it is cut into 4 square billets of 250 to 400 mm, that is, it is evenly cut into 4 square billets along the width direction, and numbered 1 to 4. The length × width × height of each billet is (300 to 500) × (250 to 400) × (180 to 300) mm, and the temperature is above 700°C.

[0038] Step S3, cooling the square billet step by step.

[0039] Use a hot transport and insulation car to deliver 4 square billets to a muffle furnace pre-heated at 700°C for 2 hours. Lower the temperature of the muffle furnace to 580-620 degrees and keep it warm for 2 hours. Lower the temperature of the muffle furnace to 480-520 degrees and keep it warm for 2 hours. Lower the temperature of the muffle furnace to 380-420 degrees and keep it warm for 2 hours. Lower the temperature of the muffle furnace to 280-320 degrees and keep it warm for 2 hours. Lower the temperature of the muffle furnace to 180-220 degrees and keep it warm for 2 hours. Lower the temperature of the muffle furnace to 80-120 degrees and keep it warm for 2 hours. Turn off the power of the muffle furnace and let it cool down naturally and slowly to room temperature.

[0040] Step S4: using the quartering method to cut the cooled billet to obtain test samples and finished billets. Specifically, it includes:

[0041] Step S41: Cut off slices of the first set value x on both sides along the width direction of 250-400 mm of the square billet, and then cut square billet slices of the second set value y to obtain first long slices and second long slices, whose length × width × height are (300-500) × y × (180-300) respectively.

[0042] Step S42: Cut the square blank sheet of the third set value z on both sides along the length direction of 300 to 500 mm to obtain the first wide sheet and the second wide sheet, whose length × width × height are z × [(250-2x-2y) to (400-2x-2y)] × (180 to 300) mm respectively; the first long sheet, the second long sheet, the first wide sheet and the second wide sheet are inspection samples.

[0043] Step S43: Thin sheets of the fourth set value m are removed from the upper and lower surfaces respectively along the height direction of 180 to 300 mm, and the remaining part is a finished square billet, whose length × width × height is [(300-2z) to (500-2z)] × [(250-2x-2y) to (400-2x-2y)] × [(180-2m) to (300-2m)] mm.

[0044] Among them, x is 20 to 40 mm; y and z are 10 to 20 mm respectively; and m is 2 to 6 mm.

[0045] Step S5: Conduct element segregation inspection and physical macrostructure inspection on the inspection sample, and prepare a spectral standard sample from the finished billet according to the inspection results. Specifically including:

[0046] Step S51: Prepare block samples.

[0047] In the length direction of the first long piece, a block samples are uniformly taken along the 1 / 4 position of the height; in the height direction of the second long piece, b block samples are uniformly taken along the 1 / 4 position of the length; in the width direction of the first wide piece, c block samples are uniformly taken along the 1 / 4 position of the height; a total of (a+b+c) block samples are obtained. The specific values ​​of a, b and c can be determined by those skilled in the art as needed, for example, a=7, b=5, c=5, of course, this is only exemplary, and a, b and c can also use other appropriate values.

[0048] Step S52: Perform element segregation inspection on the (a+b+c) block samples.

[0049] The selected block samples were tested on the direct reading spectrometer according to the methods of GB / T 4336-2016 and T / CSTM 00010.2-2017, and the elements such as Al, Si, C, S, and P were analyzed and tested. Four points were excited for each element, and the average value was calculated. Specifically:

[0050] (1) Take five elements, namely Al, Si, C, S, and P, and perform Grubbs test on the average values ​​of group a, group b, and group c data to check whether there are outliers.

[0051] (2) Take five elements, namely Al, Si, C, S, and P, and compare the data range with 1.5 times the allowable difference of GB / T 4336-2016. When the range is less than 1.5 times the allowable difference, the data is acceptable; otherwise, there is a maximum or minimum value.

[0052] (3) Take Al, Si, C, S, P and other five elements, and compare the range of the average value of the analytical data of four square billets with 1.3 times the allowable difference of GB / T4336-2016. When the range is less than 1.3 times the allowable difference, the data is acceptable, otherwise there is a maximum or minimum value.

[0053] (4) If Grubbs outliers appear, check whether the outliers are acceptable. If the data range is greater than 1.5 or 1.3 times the allowable difference of GB / T4336-2016 and T / CSTM 00010.2-2017, analyze and recheck the results. If outliers still appear, screen and eliminate the samples according to the area where the outliers exist, that is, eliminate the area corresponding to the outliers.

[0054] Step S53: Performing physical low-magnification tissue inspection on the second wide slice.

[0055] Check whether there are tissue defects such as general looseness, central looseness, ingot-shaped segregation, point segregation, subcutaneous bubbles, etc. If there are unacceptable defects, the sample must be reselected.

[0056] Step S54: preparing a spectral standard sample from the finished square billet.

[0057] According to the results of element segregation test and physical macrostructure test, block samples with acceptable data are selected. According to the relative positions of these block samples on the billet, spectral standard samples are obtained by reheating, forging, turning and finishing the finished billet.

[0058] Among them, the steps of reheating, forging, turning, finishing and the like of the finished square billet can be carried out by referring to conventional methods and will not be described in detail here.

[0059] Step S6: The spectral standard sample is subjected to a structure inspection and a uniformity test, and then chemical element determination including oxygen content is performed.

[0060] In this step, the tissue inspection can be physical low-magnification tissue inspection or metallographic microscope tissue inspection. Physical low-magnification tissue inspection or metallographic microscope tissue inspection and uniformity inspection of the spectral standard sample can be carried out by conventional methods, which will not be described in detail here.

[0061] In addition to the elements that usually need to be determined when determining the value of the spectral standard sample, the present invention also specifically determines the oxygen content. Milling machine slice Punching machine punching The oxygen content of the granular samples is determined using an oxygen and nitrogen analyzer.

[0062] Example

[0063] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0064] Example 1

[0065] In this embodiment, x=40 mm, y=20 mm, z=20 mm, m=5 mm, a=7, b=5, c=5. The method for preparing the non-oriented silicon steel spectrum standard sample in this embodiment includes the following steps:

[0066] 1. Chemical composition design

[0067] Ensure that the target element aluminum content is greater than 1.00%, silicon content is greater than 3.00%, carbon content is less than 0.0030, sulfur content is less than 0.0010%, nitrogen content is less than 0.0010%, and oxygen content is less than 0.0010%. Other chemical element compositions are designed, see Table 1.

[0068] Table 1 High grade silicon steel standard sample composition design table (weight %)

[0069] element Al Si C S N O Ingredient design 1.00-1.20 3.20-3.30 ≤0.0030 ≤0.0010 ≤0.0010 ≤0.0010 Uncertainty ≤0.02 ≤0.03 ≤0.0003 ≤0.0003 ≤0.0002 ≤0.0003 element Mn P Cr Ni Cu Ti Ingredient design ≤0.35 ≤0.015 ≤0.020 ≤0.010 ≤0.0050 ≤0.0030 Uncertainty ≤0.01 ≤0.001 ≤0.002 ≤0.001 ≤0.0003 ≤0.0003

[0070] 2. Smelting process

[0071] The raw materials with low impurity content are selected, the composition ratio is selected, hot metal desulfurization is performed, converter smelting is performed, vacuum refining is performed outside the furnace, and continuous casting is performed.

[0072] 3. Material collection

[0073] Take the 1280mm width of the continuous casting production line ingot sample, and ensure that the ingot temperature is above 700-900℃ when cutting. Take 1280mm as the width direction, 230mm as the height direction, and the continuous casting direction as the length direction. Oxygen welding cutting takes 500mm in length. Cut into 4 pieces of 320mm in the middle of the width direction and 1 / 4 near the edge, and mark them with numbers 1-4. The size of each piece is 500mm×230×320mm square billet, such as Figure 2 As shown in Figure 1, the casting temperature is above 700°C.

[0074] 4. Step-by-step cooling of the muffle furnace

[0075] The four square billets were transported to a muffle furnace preheated at 700°C by a hot transport and insulation vehicle for 2 hours.

[0076] Lower the temperature of the muffle furnace to 600±20 degrees and keep it warm for 2 hours;

[0077] Lower the temperature of the muffle furnace to 500±20 degrees and keep it warm for 2 hours;

[0078] Lower the temperature of the muffle furnace to 400±20 degrees and keep it warm for 2 hours;

[0079] Lower the temperature of the muffle furnace to 300±20 degrees and keep it warm for 2 hours;

[0080] Lower the temperature of the muffle furnace to 200±20 degrees and keep it warm for 2 hours;

[0081] Lower the temperature of the muffle furnace to 100±20 degrees and keep it warm for 2 hours;

[0082] Turn off the power of the muffle furnace, adjust the temperature to room temperature, and cool it down slowly.

[0083] 5. Quartering and preparation of test samples

[0084] Cut the billet in length×width×height direction, 500×320×230mm, into pieces. The following steps are included in sequence:

[0085] (1) Considering that the center is most likely to have segregation zones, 40 mm slices are cut off on both sides of the 320 mm width direction and discarded. Then 20 mm slices are cut off on both sides and retained, numbered as long slice 1 (i.e., the first long slice) and long slice 2 (i.e., the second long slice), to obtain a blank with 200 mm retained in the width direction, as shown in the following figure: Figure 3 shown.

[0086] (2) For the blank after the processing in step (1), 20 mm slices are cut on both sides along the 500 mm length direction, and the slices are retained and numbered as wide slice 1 (i.e., the first wide slice) and wide slice 2 (i.e., the second wide slice), so as to obtain a blank with a length direction of 460 mm. Specifically, Figure 4 shown.

[0087] (3) For the billet after processing in step (2), 5 mm of the upper and lower surfaces are milled off along the 230 mm height direction, and the surface is milled flat, leaving 220 mm in the height direction. The finished product is a square billet in the length × width × height direction, 460 mm × 200 × 220 mm, as shown in the following figure: Figure 5 shown.

[0088] 6. Segregation test

[0089] The dimensions of long piece 1 and long piece 2 are 20×230×500 mm respectively. The dimensions of wide piece 1 and wide piece 2 are 20×230×200 mm respectively.

[0090] For long film 1, in the length direction (500 mm), 7 points are evenly selected along the 1 / 4 position of the height, as shown in the following figure: Figure 6 shown.

[0091] For long piece 2, in the height direction (230 mm), 5 points are evenly selected along the 1 / 4 position of the length, as shown below: Figure 7 shown.

[0092] For wide sheet 1, in the width direction (200 mm), take 5 points evenly along the 1 / 4 position of the height, as shown below: Figure 8 shown.

[0093] 2 wide films, sent for physical low-magnification tissue examination.

[0094] The sizes of the 17 points selected above are all 35×35×20 mm, that is, the 17 points selected above are 17 block samples with sizes of 35×35×20 mm respectively.

[0095] The 17 prepared block samples were tested on a direct reading spectrometer according to the methods of GB / T 4336-2016 and T / CSTM00010.2-2017, and elements such as Al, Si, C, S, and P were analyzed and tested. Four points were excited for each element, and the average value was calculated. Specifically:

[0096] (1) Take five elements, namely Al, Si, C, S, and P, and perform Grubbs test on the average values ​​of 7 groups of data of long sheet 1, 5 groups of data of long sheet 2, and 5 groups of data of wide sheet 1 to check whether there are outliers.

[0097] (2) Take five elements, namely Al, Si, C, S, and P, and compare the data range with 1.5 times the allowable difference of GB / T 4336-2016 and T / CSTM 00010.2-2017. When the range is less than 1.5 times the allowable difference, the data is acceptable; otherwise, there is a maximum or minimum value.

[0098] (3) Take Al, Si, C, S, P and other five elements, and compare the range of the average value of the analytical data of four square billets with 1.3 times the allowable difference of GB / T4336-2016. When the range is less than 1.3 times the allowable difference, the data is acceptable, otherwise there is a maximum or minimum value.

[0099] (4) If Grubbs outliers appear, check whether the outliers are acceptable. If the data range is greater than 1.5 or 1.3 times the allowable difference of GB / T4336-2016 and T / CSTM 00010.2-2017, analyze and recheck the results. If outliers still appear, screen and eliminate the samples according to the area where the outliers exist, that is, eliminate the area corresponding to the outliers.

[0100] Table 2 Segregation test results (weight %)

[0101] serial number C Si P S Al a1 0.00265 3.267 0.0099 0.00098 1.031 a2 0.00261 3.275 0.0099 0.00083 1.016 a3 0.00268 3.265 0.0094 0.00076 1.023 a4 0.00267 3.274 0.0100 0.00088 1.021 a5 0.00262 3.285 0.0095 0.00099 1.023 a6 0.00261 3.270 0.0094 0.00075 1.035 a7 0.00270 3.278 0.0098 0.00093 1.017 b1 0.00269 3.281 0.0095 0.00077 1.025 b2 0.00266 3.266 0.0096 0.00097 1.040 b3 0.00260 3.271 0.0096 0.00097 1.021 b4 0.00264 3.266 0.0095 0.00092 1.016 b5 0.00265 3.275 0.0094 0.00086 1.032 c1 0.00263 3.256 0.0097 0.00087 1.014 c2 0.00267 3.290 0.0100 0.00081 1.015 c3 0.00264 3.288 0.0097 0.00098 1.043 c4 0.00261 3.263 0.0094 0.00091 1.025 c5 0.00263 3.260 0.0099 0.00086 1.023 average value 0.00264 3.272 0.0097 0.00088 1.025 Very bad 0.00010 0.034 0.0007 0.00024 0.028 1.5r 0.00051 0.0908 0.00075 0.00030 0.0495

[0102] Note: In Table 2, a, b, c correspond to long film 1, long film 2 and wide film 1 respectively, and "letter + number" represents the corresponding block sample, for example, "a1" represents the first block sample of long film 1, and so on.

[0103] After segregation test, there are no abnormal values ​​in the Grubbs test for 5 elements, including Al, Si, C, S, and P, and the range is less than 1.5 or 1.3 times the method allowable difference. If the segregation test is qualified, the finished billet can be further processed for forging.

[0104] 7. Preparation and processing

[0105] After reheating, forging, turning, cutting and finishing, the spectral sample is obtained. A total of about 400 yuan.

[0106] 8. Organize inspection

[0107] Randomly take a sample of the finished spectrum The microstructure inspection was carried out by physical low-power microstructure inspection. The low-power inspection report showed that the sample had no looseness, bubbles, ingot-shaped segregation, or point-shaped segregation, and fully met the requirements of the standard sample for spectral analysis. The inspection results are shown in Table 3.

[0108] Table 3 Physical low-magnification test results

[0109]

[0110] 9. Uniformity test

[0111] Randomly take 20 spectral samples Direct reading spectroscopy was used for analysis. The instrument was adjusted to the optimal analysis conditions, the experimental conditions and instrument status were kept consistent, and the uniformity of each element was tested. Statistics were performed using the variance method. Table 4.

[0112] Table 4 Uniformity test results

[0113]

[0114] According to the variance analysis method, the uniformity statistics are carried out to calculate the uneven variance S of each fixed value element of the standard sample. bb 2 and the statistic F.

[0115] When the statistic F﹤Fα, there is no significant difference in the data within and between groups, and the uniformity test is passed.

[0116] When the statistic F﹥Fα, there are significant differences in the data within and between groups, and the uniformity test fails.

[0117] Conclusion: According to the variance method, the F values ​​of each element statistic are all less than the critical value F 0.05 (1.85), indicating that the uniformity of each element in the standard sample for spectral analysis is good and meets the uniformity requirement of the standard sample.

[0118] 10. Fixed value analysis

[0119] The samples for chemical analysis were prepared in the form of chips, mixed and bottled, and then 8 laboratories were commissioned to work together to determine the value. Various analytical methods were used for determination, such as Si perchloric acid dehydrated weight method, reduced molybdenum silicate spectrophotometry and ICP-AES method.

[0120] 11. Determination of oxygen content in bean curd processing

[0121] Take finished spectrum sample Milling machine slice Punching machine punching The granular sample of about was定值 for the oxygen element content by an oxygen-nitrogen analyzer, and the oxygen element content was obtained as 0.0007%.

[0122] 12. Mathematical statistics

[0123] Statistics were performed on 32 data for each element (36 data for N element) from 8 laboratories according to the following principles:

[0124] (1) Method repeatability test: Four analysis data from each collaborating unit were examined using 1.3 times the repeatability limit (r) of the method or the allowable difference to determine whether there were outliers. After no outliers were found, the average value of each group was calculated.

[0125] (2) Normality test: The Shapiro-Wilk method was used to test the normality of all data and unit average value data for all elements. When the statistic W > W0.05, the data conforms to a normal distribution; when W0.01 < W < W0.05, the data is normally distributed or approximately normally distributed at the significance level of ɑ = 0.01 and is retained; when W < W0.01, the data is not normally distributed and is generally excluded.

[0126] (3) Outlier test: The Grubbs method was used to test for outliers in the unit average values of all elements. When the statistics Gmin and Gmax < G0.05, there are no outliers; when G0.01 > Gmin and Gmax > G0.05, there are no outliers at the significance level of ɑ = 0.01 and no outlier treatment is performed; when Gmin and Gmax > G0.01, there are highly significant outliers and they are generally excluded.

[0127] (4) Equal precision test: The Cochran method was used to perform an equal precision test on all elements; when the statistic C < C0.05, the data has equal precision and there are no abnormalities in each component; when C0.01 > C > C0.05, the data has equal precision at the significance level of ɑ = 0.01 and is regarded as having equal precision; when C > C0.01, there is a significant unequal precision situation and it is generally excluded.

[0128] Statistical conclusion: Mathematical statistics were performed on all the certified values, and all were qualified.

[0129] The total average value and the standard deviation S′ were calculated with equal precision among the average values. Finally, the standard value and the standard deviation S were determined. The numerical rounding was carried out in accordance with GB / T 8170 "Rules for Rounding of Numerical Values and Representation and Judgment of Limit Numerical Values", and the standard deviation was carried out according to the principle of rounding up only.

[0130] 13. Determination of standard value and uncertainty

[0131] (1) Determination of standard value It should be noted that the text seems to be incomplete in some parts, especially the "定值" in the first line which might need more context to be accurately translated as a proper term. Here "定值" is tentatively translated as "certified value".

[0132] The mean of the average values ​​of the element's fixed value data from each laboratory is taken as the standard value of the element.

[0133] (2) Determination of standard deviation

[0134] The standard deviation of the mean of the average values ​​of the element value data of each laboratory is taken as the standard deviation of the element.

[0135] (3) Determination of standard uncertainty

[0136] The standard uncertainty of the characteristic value is calculated according to the following formula.

[0137]

[0138] in:

[0139] (4) Determination of expanded standard uncertainty

[0140] The calculation formula for the expanded uncertainty of the characteristic value is: U = ku CRM

[0141] Uncertainty component u bb 2 This is the S in the uniformity statistics table. bb 2 , due to the good stability of metallurgical standard samples, u lts (Long-term stability uncertainty) and u sts (short-term stability uncertainty) can be ignored, S is the single measurement standard deviation of fixed value statistics, n is the number of data sets, u char is the standard uncertainty caused by the measurement, k is the coverage factor, and when calculated according to the 95% confidence interval, k=2.

[0142] Table 5 Summary of fixed value data

[0143]

[0144] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other substitutions, modifications, combinations, changes, simplifications, etc. made without departing from the spirit and principles of the present invention shall be equivalent replacement modes and shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a non-oriented silicon steel spectrum standard sample, characterized in that: include: Step S1, smelting the ingot according to the designed chemical composition; Step S2, hot cutting the ingot to obtain a square billet; Wherein, the thermal cutting refers to ensuring that the temperature of the ingot is between 700 and 900°C during cutting; Step S3, cooling the billet step by step; Step S4, cutting the cooled billet by a quartering method to obtain test samples and finished billets; Step S5, performing element segregation inspection and physical macrostructure inspection on the inspection sample, and preparing a spectral standard sample from the finished square billet according to the inspection results; Step S6, the spectral standard sample is subjected to a tissue inspection and a uniformity test to determine the chemical elements including the oxygen content; The quartering method includes: cutting off thin slices of a first set value x on both sides along the width direction of 250~400mm of the square billet, and then cutting square billet slices of a second set value y to obtain a first long slice and a second long slice, whose length×width×height is (300~500)×y×(180~300); cutting square billet slices of a third set value z on both sides along the length direction of 300~500mm to obtain a first wide slice and a second wide slice, whose length×width×height is z×[(250-2x-2y)~(400-2x-2y)]×( 180~300) mm; along the height direction of 180~300 mm, the thin sheets of the fourth set value m are removed from the upper and lower surfaces respectively, and the remaining part is the finished square billet, whose length × width × height is [(300-2z)~(500-2z)]×[(250-2x-2y)~(400-2x-2y)]×[(180-2m)~(300-2m)]mm; the first long sheet, the second long sheet, the first wide sheet and the second wide sheet are inspection samples; among them, x is 20~40 mm, y and z are 10~20 mm respectively, and m is 2~6 mm.

2. The method according to claim 1, characterized in that: In step S1, the designed chemical composition is calculated by weight percentage: Al 1.00%~1.20%, Si 3.00%~3.50%, C≤0.0030%, S≤0.0010%, N≤0.0010%, O≤0.0010%, Mn≤0.35%, P≤0.015%, Cr≤0.020%, Ni≤0.010%, Cu≤0.0050%, Ti≤0.0040%, and the balance is iron and unavoidable impurity elements.

3. The method according to claim 1, characterized in that: In step S2, the width of the ingot is 1000-1600 mm and the height is 180-300 mm; the thermal cutting includes: cutting a length of 300-500 mm along the length direction of the ingot, and then cutting it into 4 square billets evenly along the width direction, and the length × width × height of each square billet is (300-500) × (250-400) × (180-300) mm.

4. The method according to claim 3, characterized in that: In step S3, the step-by-step step cooling includes: sending the square billet to a muffle furnace pre-insulated at 700°C for 2 hours; adjusting the temperature of the muffle furnace to 580-620 degrees and keeping it warm for 2 hours; adjusting the temperature of the muffle furnace to 480-520 degrees and keeping it warm for 2 hours; adjusting the temperature of the muffle furnace to 380-420 degrees and keeping it warm for 2 hours; adjusting the temperature of the muffle furnace to 280-320 degrees and keeping it warm for 2 hours; adjusting the temperature of the muffle furnace to 180-220 degrees and keeping it warm for 2 hours; adjusting the temperature of the muffle furnace to 80-120 degrees and keeping it warm for 2 hours; and naturally cooling to room temperature.

5. The method according to claim 1, characterized in that: In step S5, a block samples are uniformly taken along the 1 / 4 position of the height in the length direction of the first long piece; b block samples are uniformly taken along the 1 / 4 position of the length in the height direction of the second long piece; c block samples are uniformly taken along the 1 / 4 position of the height in the width direction of the first wide piece; element segregation test is performed on the (a+b+c) block samples; and physical macrostructure test is performed on the second wide piece.

6. The method according to claim 5, characterized in that: In step S5, the element segregation test includes Grubbs test and range analysis for the elements Al, Si, C, S, and P.

7. The manufacturing method according to claim 1, characterized in that: In step S6, when determining the oxygen content, the spectral standard sample is made into a granular sample with a size of ø5×3mm, and then the oxygen content is determined.

8. A non-oriented silicon steel spectrum standard sample, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 7.

9. The non-oriented silicon steel spectrum standard sample according to claim 8, characterized in that: Calculated by weight percentage: Al 1.00%~1.20%, Si 3.00%~3.50%, C≤0.0030%, S≤0.0010%, N≤0.0010%, O≤0.0010%, Mn≤0.35%, P≤0.015%, Cr≤0.020%, Ni≤0.010%, Cu≤0.0050%, Ti≤0.0040%, and the balance is iron and unavoidable impurity elements.

10. The non-oriented silicon steel spectrum standard sample according to claim 9, characterized in that: Calculated by weight percentage, it includes: Al 1.03%, Si 3.26%, C 0.0026%, S 0.0008%, N 0.0006%, O 0.0007%, Mn 0.29%, P0.010%, Cr 0.018%, Ni 0.005%, Cu 0.0028%, Ti 0.0021%, and the balance is iron and unavoidable impurity elements.

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