A method for sampling and preparing spectral standards for nickel-iron water

Abstract

This invention provides a method for sampling and preparing spectral standards for molten nickel-iron, including the following steps: designing the chemical composition of the standard, smelting molten nickel-iron, assembling the standard casting mold, material sampling, marking, chemical segregation testing, physical segregation testing, sample processing, sampling testing for standard homogeneity, and value determination. The molten nickel-iron standard prepared by this method has a homogeneous and stable composition, and its application in direct-reading spectral analysis can effectively improve the accuracy of molten nickel-iron analysis in steelmaking laboratories.

Description

Technical Field

[0001] This invention relates to the field of nickel-iron molten metal standard sample preparation technology, specifically a method for sampling and preparing nickel-iron molten metal spectral standard samples. Background Technology

[0002] The applicant uses molten nickel-iron as the main raw material to smelt stainless steel. The main characteristics of the molten nickel-iron smelted by the applicant are: C content between 2.3% and 3.3%, Si content between 0.6% and 1.5%, S content between 0.1% and 0.4%, Cr content between 1.5% and 2.5%, and Ni content between 6.0% and 11.0%. The stainless steel products are characterized by being hard and brittle, having low thermal conductivity, and experiencing different cooling rates between the internal and external parts, making them prone to cracking.

[0003] Rapid chemical composition analysis of molten nickel-iron samples typically uses direct-reading spectrometers. Direct-reading spectroscopy is a relative measurement method that requires calibration with appropriate molten nickel-iron standards to obtain accurate analytical data. Laboratories have a significant annual demand for molten nickel-iron standards. Currently, there are no commercially available spectral standards suitable for applicants' specific molten nickel-iron samples, and existing methods for developing molten iron standards cannot meet the needs of testing and analysis. Summary of the Invention

[0004] The purpose of this invention is to provide a method for sampling and preparing spectral standards for nickel-iron molten metal. The nickel-iron molten metal standards prepared by this method have uniform and stable composition. When applied to direct-reading spectral analysis, they can effectively improve the accuracy of nickel-iron molten metal analysis in steelmaking laboratories.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for sampling and preparing a nickel-iron molten metal spectral standard, comprising the following steps:

[0006] 1) Design of standard chemical composition,

[0007] Based on product standard requirements and actual product control needs, the chemical composition of the standard sample is precisely designed to meet the requirement that the composition of each element before the furnace is similar to that of the element in the finished product analysis.

[0008] 2) Nickel-iron smelting,

[0009] Laterite nickel ore, limestone, and reducing agent are screened and crushed in the raw material yard and preparation room, then mixed and fed into a rotary kiln. The raw materials are dried, roasted, and pre-reduced to produce nickel slag at 1000℃, which is then smelted into molten nickel iron in a submerged arc furnace.

[0010] 3) Assembly of the standard sample casting mold.

[0011] The casting mold includes an upper mold, a bottom mold, and a bottom mold gasket. A through-flow casting cavity is provided within the upper mold. The bottom mold gasket is disposed within the bottom mold. The lower part of the upper mold can be inserted into the bottom mold, and the bottom mold gasket can seal the bottom of the casting cavity. The upper mold includes several upper mold components, which can be nested together sequentially from top to bottom. The casting cavity has a cylindrical structure. The upper mold, bottom mold, and bottom mold gasket are all made of copper. The assembly steps of the casting mold are as follows: first, install the bottom mold gasket in the insertion slot of the bottom mold; then, insert the bottom of one upper mold component into the insertion slot of the bottom mold. After insertion, the remaining upper mold components are nested and inserted sequentially onto the upper part of the corresponding upper mold components, thus completing the assembly of the casting mold. After assembly, the casting mold is placed vertically with the pouring gate at the top.

[0012] 4) Material collection,

[0013] The molten nickel-iron is kept above 1500℃. It is then scooped out using a high-temperature resistant ceramic spoon and poured into the casting cavity of the mold. The casting mold is then allowed to cool naturally at an environment of 20℃-35℃ until it cools into a rod-shaped molten nickel-iron billet. After cooling and shaping, the mold is removed to obtain the standard sample billet. Depending on the requirements, multiple standard sample billets or a single standard sample billet may be obtained.

[0014] Mark the top and bottom of the cylindrical standard blank, with the end furthest from the pouring gate being the bottom. After marking the top and bottom, cut off a small section from the top and bottom of the standard blank, and use the remaining part as the initial standard blank for subsequent applications.

[0015] 5) Marking,

[0016] When there are multiple standard sample blanks, the initial standard sample blanks are distinguished and marked according to the sampling order. After marking, each initial standard sample blank is evenly divided into multiple segments from bottom to top.

[0017] When using a single standard sample blank, the standard sample blank is evenly cut into multiple segmented blanks from bottom to top, and each segmented blank is marked sequentially from bottom to top.

[0018] 6) Chemical composition segregation test,

[0019] The C, Si, S, Cr, and Ni elements in the corresponding segmented billets were analyzed and tested using a spark source atomic emission spectrometer in accordance with the GB / T42794-2023 method.

[0020] The initial standard sample blanks were tested using the analytical test data. The rules were as follows: (1) When there are multiple standard sample blanks, the top and bottom segments of each initial standard sample blank were taken according to the original multi-segment division marks of the initial standard sample blank. The remaining part after the top and bottom segments of the initial standard sample blank were removed was the final standard sample blank; (2) When there is a single standard sample blank, all segments were taken; (3) The measurement surface of each segment blank was marked with the position of the circumscribed vertex of the regular polygon to determine the excitation measurement position. The average value of the excitation measurement position of each mark was measured multiple times and used as the basic data for the Grubbs test and F test.

[0021] 7) Physical segregation test,

[0022] After passing the chemical composition segregation test, the physical segregation test shall be carried out according to the following rules: (1) When there are multiple standard sample billets: the excitation detection surfaces of the bottom and top sections of each initial standard sample billet shall be used as the physical segregation test surfaces and sent for physical low magnification microstructure test; (2) When there is a single standard sample billet: the excitation detection surfaces of the bottom, middle and top sections of the standard sample billet shall be used as the physical segregation test surfaces and sent for physical low magnification microstructure test.

[0023] 8) Sample processing,

[0024] S1. Rough grinding; The rough grinding method is to use a grinding wheel to grind the outer surface of the blank to remove burrs and attachments from the surface of the blank; when there are multiple standard blanks, rough grinding is performed on each final standard blank; when there is a single standard blank, rough grinding is performed on each segment of the blank.

[0025] S2. Fine grinding; The fine grinding method is to use fine sandpaper to grind the surface of the blank to increase the smoothness of the blank surface; when there are multiple standard blanks, fine grinding is performed on each final standard blank section; when there is a single standard blank, fine grinding is performed on each section of the blank.

[0026] S3. Cutting and segmenting; This step is only implemented when there are multiple standard sample blanks. The implementation method is as follows: mark each final standard sample blank with multiple equally spaced segments, and divide the final standard sample blank from each mark.

[0027] 9) Sampling inspection of standard sample homogeneity.

[0028] The uniformity test of a single standard sample billet has been completed in step 6) above, so there is no need to perform a sampling inspection of the uniformity of a single standard sample billet in this step.

[0029] When multiple standard billet samples are used, randomly select segmented billets and inspect them according to the GB / T42794-2023 method. Use a spark source atomic emission spectrometer to test the uniformity of elements that need to be determined.

[0030] 10) Production suitability check,

[0031] When using multiple standard sample billets, the production suitability check is performed on the measured values ​​of the randomly sampled segmented billets in step 9). When using a single standard sample billet, the production suitability check is performed on the measured values ​​of each segmented billet obtained in step 6. Specifically, the average measured value of the measured surface of each segmented billet is taken as the measured value of that segmented billet. The standard deviation of the measured value is calculated, and the standard deviation is compared with the production control range. If the standard deviation × 6 < the production control range, then it is suitable for production.

[0032] 11) Constant value,

[0033] The standard value and expanded uncertainty are obtained by setting the value of the segmented billet according to the existing known setting method.

[0034] Preferably, the standard sample comprises the following components by weight percentage: C: 2.8%-3.0%, Si: 0.9%-1.0%, S: 0.22%-0.25%, Cr: 1.9%-2.2%, Ni: 8.0%-9.0%; the balance being iron and impurities.

[0035] Furthermore, the volume of the high-temperature resistant ceramic spoon is between 500ml and 1000ml, the wall thickness of the upper mold assembly is between 35mm and 50mm, and the standard sample blank is cut and discarded at the bottom 50mm and the top 40mm after cooling, molding and demolding.

[0036] Furthermore, when using multiple standard sample blanks, the initial standard sample blanks are numbered A, B, C, D, ... according to the sampling order; each initial standard sample is evenly marked with 20 segments from bottom to top, with the marking numbers 01, 02, 03, ... 20; the top and bottom segments of each initial standard sample blank are marked on their end faces, so that the end face of the segment near the bottom of the initial standard sample blank contains "+", and the end face near the top of the initial standard sample blank contains "-"; when using a single standard sample blank, the initial standard sample blank is evenly divided into 20 segments, with the marking numbers 01, 02, 03, ... 20; each segment is marked on its end face, so that the end face of the segment near the bottom of the initial standard sample blank contains "+", and the end face near the top of the initial standard sample blank contains "-".

[0037] Furthermore, in the chemical composition segregation test procedure:

[0038] When using multiple standard billet samples, the end faces of the bottom segments marked with "01+" and the top segments marked with "20+" are used as the excitation test surfaces. At least three excitation positions are evenly marked on the corresponding excitation test surfaces of each segment. During the excitation test, each excitation position is subjected to 2-3 excitations. The average measurement value after multiple excitations at each position is used as the basic data for the test. The average measurement results of the top and bottom segments of each initial standard billet are used as two measurements for each standard billet. The Grubbs test is used to remove outlier final standard billets. After removing outlier final standard billets, the average measurement values ​​at different positions of the top and bottom segments of the same initial standard billet are used as the within-group data. The average measurement values ​​of the top and bottom segments of each initial standard billet are used as the between-group data. The F-test is used to determine the uniformity of each final standard billet.

[0039] When testing a single standard billet, the end faces of each segmented billet marked with a "+" sign are used as the excitation test surfaces. At least three excitation positions are uniformly marked within the excitation test surfaces of all segmented billets. During the excitation test, 2-3 excitations are performed at each excitation position. The average value of the measurements after multiple excitations at each excitation position is used as the basic data for the test. The average value of the measurements at different excitation positions on the same measurement surface is used as the average value of the measurement surface. The Grubbs test is used to test the average value of each measurement surface in the standard billet. If the statistical results are abnormal, a new standard billet is taken. If no abnormality is found in the statistical results, the measurements at different excitation positions on the same measurement surface are used as the within-group data. The average value of each measurement surface is used as the between-group data. The F-test is used to determine the uniformity of the single standard billet. The uniformity test data of this test is used as the final uniformity test data for the single standard billet.

[0040] Furthermore,

[0041] When using multiple standard blanks, the end face of the bottom section blank marked with "01+" is used as the physical segregation detection surface, and the end face of the top section blank marked with "20+" is used as the physical segregation detection surface. After the physical segregation inspection surface is determined, it is processed by a milling machine and then sent for physical low-magnification microstructure inspection.

[0042] When using a single standard sample billet, the top, middle, and bottom segments of the initial standard sample billet are used as test billets. Simultaneously, the end face of the top segment marked "01+" is used as the physical segregation detection surface; the end face of the bottom segment marked "20+" is used as the physical segregation inspection surface; and the end face of the middle segment marked "10+" is used as the physical segregation inspection surface. After the physical segregation inspection surfaces are determined, they are processed by a milling machine and then sent for low-magnification physical microstructure inspection.

[0043] Furthermore,

[0044] The random sampling rules are as follows: (1) Multiple standard blanks are arranged horizontally from top to bottom according to the initial sampling mark order. A sampling position is taken at a fixed distance. A certain number of segmented blanks are taken from each column according to the known sampling ratio. (2) The measured surface of the extracted segmented blanks is marked with multiple excitation positions according to the position of the circumscribed vertex of the regular polygon. The excitation position of each mark is measured multiple times and the average value is taken as the basic data for uniformity test. (3) The measured values ​​of different positions on the same measured surface of each segmented blank are taken as the data within the group. The average value of each measured surface is taken as the data between the groups. The uniformity of the standard blanks is tested by the F uniformity test method. If the statistical results are abnormal, the standard blanks are taken again.

[0045] The beneficial effects of this invention are: the nickel-iron molten standard sample prepared by this method has uniform and stable composition, and when applied to direct-reading spectral analysis, it can effectively improve the accuracy of nickel-iron molten analysis in steelmaking laboratories; at the same time, it can save on the cost of standard sample procurement. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some preferred embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 A schematic diagram of cutting the casting blank to form the initial standard blank;

[0048] Figure 2 A schematic diagram showing the marking of multiple initial standard blanks;

[0049] Figure 3 A schematic diagram illustrating the sampling and inspection of multiple initial standard blanks;

[0050] Figure 4 A schematic diagram illustrating the marking of a single initial standard blank;

[0051] Figure 5 A schematic diagram showing several excitation position marks on the end face of a segmented billet;

[0052] Figure 6 A schematic diagram of sampling for physical segregation testing of a single initial standard billet;

[0053] Figure 7 A schematic diagram of random sampling arrangement for multiple final standard sample blanks;

[0054] Figure 8 This is a low-magnification photograph of the physical segregation inspection of segmented billets in one embodiment.

[0055] Figure 9 A schematic diagram of the overall structure of the casting mold;

[0056] Figure 10 This is a schematic diagram of the assembly of the upper mold component and the bottom mold;

[0057] In the diagram: 1 Upper mold, 11 Casting cavity, 111 Sub-casting cavity, 12 Upper mold assembly, 2 Bottom mold, 3 Bottom mold gasket. Detailed Implementation

[0058] The following will describe specific embodiments and appendices. Figure 1-10 The technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only some preferred embodiments of the present invention, and not all embodiments. Those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0059] This invention provides a method for sampling and preparing a nickel-iron molten metal spectral standard, comprising the following steps:

[0060] 1) Design of standard chemical composition,

[0061] Based on product standard requirements and actual product control needs, a precise chemical composition design was implemented for the standard sample to ensure that the composition of each element before furnace operation is similar to that of the finished product. The main characteristics of the nickel-iron molten metal smelted by the applicant are: C content between 2.3% and 3.3%, Si content between 0.6% and 1.5%, S content between 0.1% and 0.4%, Cr content between 1.5% and 2.5%, and Ni content between 6.0% and 11.0%, with the above element proportions being weight percentages. Therefore, in the actual preparation process, the control range of the main components of the standard sample can be shown in Table 1.

[0062] Table 1. Control range of main components of standard samples

[0063]

[0064] 2) Nickel-iron smelting,

[0065] Laterite nickel ore, limestone, and reducing agent are screened and crushed in the raw material yard and preparation room, then mixed and fed into a rotary kiln. The raw materials are dried, roasted, and pre-reduced to produce nickel slag at 1000℃, which is then smelted into molten nickel iron in a submerged arc furnace.

[0066] 3) Assembly of the standard sample casting mold.

[0067] The casting mold (e.g.) Figure 8 and Figure 9 (As shown) includes an upper mold 1, a bottom mold 2, and a bottom mold gasket 3. A vertically penetrating casting cavity 11 is provided within the upper mold 1. In practical applications, molten nickel-iron is rapidly cooled and formed within the casting cavity 11. The bottom mold gasket 3 is located within the bottom mold 2. The lower part of the upper mold 1 can be inserted into the bottom mold 2, and the bottom mold gasket 3 can seal the bottom of the casting cavity 11. After the bottom of the casting cavity 11 is sealed by the bottom mold gasket 3, there will be no bottom leakage problem when molten nickel-iron is poured from the top of the casting cavity 11, thus ensuring the cooling and forming of the billet. The upper mold 1 includes several upper mold components 12, which can be nested together from top to bottom. The casting cavity 11 has a cylindrical structure. The number of upper mold components 12 determines the length of the billet. Therefore, in practical applications… The number of upper mold components 12 can be selected according to requirements to meet the requirements of producing blanks of a specific length. The upper mold 1, the bottom mold 2, and the bottom mold shim 3 are all made of copper. Copper has a high thermal conductivity, which is conducive to the rapid heat dissipation of molten nickel-iron, thereby improving the forming quality of the blank. The mold wall thickness of the upper mold component 12 can be set to 35mm-50mm. At the same time, the inner diameter of the pouring cavity 11 is set to 35mm. The assembly steps of the pouring mold are as follows: first, install the bottom mold shim 3 in the insertion groove of the bottom mold 2. Then, insert the bottom of one upper mold component 12 into the insertion groove of the bottom mold 2. After the insertion is completed, the remaining upper mold components 12 are nested and inserted into the upper part of the corresponding upper mold components in sequence, thereby completing the assembly of the pouring mold. After the assembly is completed, the pouring mold is placed in a vertical position with the pouring gate at the top.

[0068] 4) Material collection,

[0069] The molten nickel-iron is kept above 1500℃. It is then scooped out using a high-temperature resistant ceramic spoon with a volume between 500ml and 1000ml and poured into the casting cavity 11 of the mold. The casting mold is then allowed to cool naturally at an environment of 20℃-35℃ until it cools into a rod-shaped molten nickel-iron billet. After cooling and shaping, the mold is removed to obtain the standard sample billet. Depending on the requirements, multiple standard sample billets or a single standard sample billet may be obtained.

[0070] Mark the top and bottom of the cylindrical standard sample blank, with the end furthest from the pouring gate designated as the bottom. After marking the top and bottom, cut off a small section from both the top and bottom of the standard sample blank. Specifically, cut and discard sections 50mm from the bottom and 40mm from the top of the blank (e.g., ...). Figure 1 (As shown); the remaining portion will be used as the initial standard blank for subsequent applications.

[0071] 5) Marking,

[0072] When using multiple standard sample blanks, the initial standard sample blanks are distinguished and marked according to the sampling order. After marking, each initial standard sample blank is evenly divided into multiple segments from bottom to top. Specifically, when using multiple standard sample blanks (e.g.) Figure 2 As shown), the initial standard blanks are numbered A, B, C, D, ... according to the sampling order; each initial standard blank is evenly marked with 20 segments from bottom to top, and the marking numbers are 01, 02, 03 ... 20.

[0073] When using a single standard sample blank (e.g.) Figure 4 As shown), the standard sample blank is evenly cut into multiple segments from bottom to top, and each segment is marked from bottom to top. When using a single standard sample blank, the initial standard sample blank is evenly divided into 20 segments, and the marking numbers are: 01, 02, 03...20.

[0074] 6) Chemical composition segregation test,

[0075] The C, Si, S, Cr, and Ni elements in the corresponding segmented billets were analyzed and tested using a spark source atomic emission spectrometer in accordance with the GB / T42794-2023 method.

[0076] The initial standard sample billet was tested using Grubbs' test and F test based on the analytical test data. The rules were as follows: (1) When there are multiple standard sample billets, the top and bottom segments of each initial standard sample billet were taken according to the original multi-segment division marks of the initial standard sample billet (e.g., Figure 3 As shown), mark the end faces of the top and bottom segments of each initial standard sample blank, so that the end face of the segment near the bottom of the initial standard sample blank contains "+", and the end face near the top of the initial standard sample blank contains "-"; for example, the two end faces of the bottom segment of the initial standard sample blank labeled A are marked as "A01+" and "A01-"; for example, the two end faces of the top segment of the initial standard sample blank labeled B are marked as "B20+" and "B20-". The remaining part after the top and bottom segment blanks of the initial standard sample blank are removed is the final standard sample blank; (2) When using a single standard sample blank, take all the segment blanks and mark the end faces of each segment blank (e.g. Figure 4 As shown), the end faces of the segmented billets near the bottom of the initial standard billet contain "+", and the end faces near the top of the initial standard billet contain "-"; for example, the end faces of segment 01 are marked as "01+" and "01-", and the end faces of segment 02 are marked as "02+" and "02-"; 3. The measurement surface of each segmented billet is marked with the excitation measurement position according to the position of the circumscribed vertex of the regular polygon (e.g., Figure 5As shown), the average value of multiple measurements at each marked excitation measurement position is used as the basis data for Grubbs' test and F-test. When using multiple standard billet samples, the end face of the bottom segment billet marked with "01+" is used as the excitation detection surface, and the end face of the top segment billet marked with "20+" is used as the excitation detection surface. At least three excitation positions are evenly marked on the corresponding excitation detection surface of each segment billet. In this specific embodiment, three excitation positions are marked on the excitation detection surface. During excitation testing, 2-3 excitations are performed at each excitation position. In this specific embodiment, three excitation tests are performed at each excitation position. The average value of measurements after multiple excitations at the excitation location is used as the basic data for testing. The average value of the measurement results of the top and bottom segments of each initial standard billet is used as two measurements for each standard billet. The Grubbs test is used to remove outlier final standard billets. After removing outlier final standard billets, the average values ​​of measurements at different locations of the top and bottom segments of the same initial standard billet are used as within-group data. The average values ​​of the measurement results of the top and bottom segments of each initial standard billet are used as between-group data. The F-test is used to determine the uniformity of each final standard billet.

[0077] When testing a single standard sample billet, the end faces of each segmented billet marked with a "+" sign are used as the excitation detection surfaces. At least three excitation positions are uniformly marked on the excitation detection surfaces of all segmented billets. In this specific embodiment, three excitation positions are set on each excitation detection surface. During the excitation test, 2-3 excitations are performed at each excitation position. In this specific embodiment, three excitation tests are performed at each excitation position. The average value of the measurements after multiple excitations at each excitation position is used as the basic data for the test. The average value of the measurements at different excitation positions on the same measurement surface is used as the average value of the measurement surface. The Grubbs test is used to test the average value of each measurement surface in the standard sample billet. If the statistical result is abnormal, a new standard sample billet is taken. If the statistical result shows no abnormality, the measurements at different excitation positions on the same measurement surface are used as the within-group data. The average value of each measurement surface is used as the between-group data. The F test is used to determine the uniformity of the single standard sample billet. The uniformity test data of this test is used as the final uniformity test data of the single standard sample billet.

[0078] 7) Physical segregation test,

[0079] After passing the chemical composition segregation test, the physical segregation test shall be carried out according to the following rules: (1) When there are multiple standard sample billets: the excitation detection surfaces of the bottom and top sections of each initial standard sample billet shall be used as the physical segregation test surfaces and sent for physical low magnification microstructure test; (2) When there is a single standard sample billet: the excitation detection surfaces of the bottom, middle and top sections of the standard sample billet shall be used as the physical segregation test surfaces and sent for physical low magnification microstructure test.

[0080] Specifically, when there are multiple standard sample billets, the end face of the bottom segment billet marked with "01+" is used as the physical segregation detection surface, and the end face of the top segment billet marked with "20+" is used as the physical segregation detection surface; after the physical segregation inspection surface is determined, it is sent for physical low magnification microstructure inspection.

[0081] When using a single standard sample billet, the top, middle, and bottom segments of the initial standard sample billet are used as test billets. Simultaneously, the end face of the top segment marked "01+" is used as the physical segregation detection surface; the end face of the bottom segment marked "20+" is used as the physical segregation inspection surface; and the end face of the middle segment marked "10+" is used as the physical segregation inspection surface. After the physical segregation inspection surfaces are determined, they are sent for low-magnification physical microstructure analysis.

[0082] 8) Sample processing,

[0083] S1. Rough grinding; The rough grinding method is to use a grinding wheel to grind the outer surface of the blank to remove burrs and attachments from the surface of the blank; when there are multiple standard blanks, rough grinding is performed on each final standard blank; when there is a single standard blank, rough grinding is performed on each segment of the blank.

[0084] S2. Fine grinding; The fine grinding method is to use fine sandpaper to grind the surface of the blank to increase the smoothness of the blank surface; when there are multiple standard blanks, fine grinding is performed on each final standard blank section; when there is a single standard blank, fine grinding is performed on each section of the blank.

[0085] S3. Cutting and segmenting; This step is only implemented when there are multiple standard sample blanks. The implementation method is as follows: mark each final standard sample blank with multiple equally spaced segments, and divide the final standard sample blank from each mark.

[0086] 9) Sampling inspection of standard sample homogeneity.

[0087] The uniformity test of a single standard sample billet has been completed in step 6) above, so there is no need to perform a sampling inspection of the uniformity of a single standard sample billet in this step.

[0088] When there are multiple standard sample billets, randomly select segmented billets and inspect them according to the GB / T42794-2023 method. Use a spark source atomic emission spectrometer to test the uniformity of the elements that need to be determined. Specifically, the random sampling rules are as follows: (1) For multiple standard sample billets, arrange the final standard sample billets after division from top to bottom in the order of the initial material sampling marks (e.g., Figure 6As shown), a sampling position is set at fixed intervals, and a certain number of segmented billets are drawn from each column according to a known sampling ratio. Specifically, one segmented billet can be randomly drawn from each column of the arranged final standard billets. For example, if there are four final standard billets, labeled A, B, C, and D, and these four final standard billets are divided into 20 equal segments, then the segmented billets of the four final standard billets A, B, C, and D... The markings are as follows: A standard sample blanks: A01, A02, A03…A19, A20; B standard sample blanks: B01, B02, B03…B19, B20; C standard sample blanks: C01, C02, C03…C19, C20; D standard sample blanks: D01, D02, D03…D19, D20; When drawing samples, one is randomly selected from the vertical columns “A1, B1, C1, and D1”. One sample is randomly selected from the columns “A2, B2, C2 and D2”, one sample is randomly selected from the columns “A3, B3, C3 and D3”, and one sample is randomly selected from the columns “A4, B4, C4 and D4”, for a total of 20 randomly selected segmented billet samples; (2) The measured surfaces of the selected segmented billets are marked with multiple excitation positions according to the position of the circumscribed vertex of the regular polygon. The excitation position of each marked position is measured multiple times and the average value is taken as the basic data for uniformity test. In this step, the marking method of the end face of each segmented billet can be adopted as the end face marking method in step 6); (3) The measured values ​​of different positions of the same measured surface of each segmented billet are used as the data within the group; the average value of each measured surface is used as the data between groups. The uniformity of the standard sample billet is tested using the F uniformity test method. If the statistical results are abnormal, the standard sample billet is re-selected.

[0089] 10) Production suitability check,

[0090] When using multiple standard sample billets, the production suitability check is performed on the measured values ​​of the randomly sampled segmented billets in step 9). When using a single standard sample billet, the production suitability check is performed on the measured values ​​of each segmented billet obtained in step 6. Specifically, the average measured value of the measured surface of each segmented billet is taken as the measured value of that segmented billet. The standard deviation of the measured value is calculated, and the standard deviation is compared with the production control range. If the standard deviation × 6 < the production control range, then it is suitable for production.

[0091] 11) Constant value,

[0092] The standard value and expanded uncertainty are obtained by setting the value of the segmented billet according to the existing known setting method.

[0093] According to the disclosed standard preparation method, a specific embodiment of the standard preparation is as follows:

[0094] (1) Design of standard chemical composition,

[0095] The main chemical composition of the standard samples is designed as shown in Table 2:

[0096] Table 2 Control range of main components of standard samples

[0097]

[0098] (2) Nickel-iron smelting,

[0099] Laterite nickel ore, limestone, and reducing agent are screened and crushed in the raw material yard and preparation room, then mixed and fed into a rotary kiln. The raw materials are dried, roasted, and pre-reduced to produce nickel slag at 1000℃, which is then smelted into molten nickel iron in a submerged arc furnace.

[0100] (3) Assembly of the standard sample casting mold,

[0101] Place the bottom mold shim 3 into the bottom mold 2, then insert an upper mold assembly 12 onto the bottom mold 2. Then, sequentially insert several upper mold assemblies 12 onto this upper mold assembly. Using this casting mold, a standard sample blank with dimensions of Φ35mm × 1.2m can be produced.

[0102] (4) Taking materials,

[0103] To ensure the molten nickel is kept above 1500℃, the molten iron is scooped out using a high-temperature resistant ceramic spoon and poured into the casting cavity of the mold. The casting mold is then allowed to cool naturally at an environment of 20℃-35℃ until it cools into a rod-shaped molten nickel billet. After cooling and forming, the mold is removed to obtain a standard sample billet. In this specific step, only one standard sample billet was taken.

[0104] (5) Marking,

[0105] The nickel-iron standard sample billet is marked with "K". It is cut and discarded at 50mm from the bottom and 40mm from the top. The bottom of the billet is the end furthest from the pouring port of the mold, and the top is the end furthest from the pouring port. Twenty segments are evenly marked from bottom to top, each 50mm high. These segments are marked K01, K02, K03...K20. After marking, the billet is cut into 20 segments at each marked point. Each segment is then distinguished by marking the top and bottom faces. The bottom face of the segment is marked with a "+", and the top face with a "-". For example, the K01 segment is marked K01+ and K01-; the K02 segment is marked K02+ and K02-.

[0106] (6) Chemical composition segregation test,

[0107] Specify the end face of each segmented blank with a "+" mark as the chemical segregation detection surface, and uniformly mark 3 excitation positions on the excitation detection surface; conduct sub-inspections according to the method of GB / T42794-2023, and use a direct-reading spectrometer to analyze and test elements C, Si, S, Cr, and Ni. During excitation detection, each excitation position is excited 3 times, and the average value of the 3 excitation data is taken as the basic data for the Grubbs test and F test method at different positions of the excitation surface; when conducting the Grubbs test, the average value of the measurement values at different positions on the same measurement surface is used as the average value of the measurement surface, and the Grubbs test is used to test the average value of each measurement surface of the blank sample. As shown in the following table data, all are qualified;

[0108] Table 3 Measurement values by Grubbs method

[0109]

[0110] When conducting the F test method for detection, the measurement values at each excitation position are used as the within-group data; the average value of all measurement results of each standard sample blank is obtained as the between-group data, and the F test method is used to judge the uniformity of the standard sample blank. As shown in the following table data, all are qualified;

[0111] Table 4 Measurement values by F method at 95% confidence level

[0112]

[0113] (7)Physical segregation inspection,

[0114] Select the end faces of K01+, k10+ and K20+ as the physical segregation detection end faces, and send them for physical macrostructure inspection. There are no defects on the surface; the macrostructure inspection photos are as Figure 6 shown;

[0115] (8)Sample processing,

[0116] First, use a grinding wheel to polish the surface of each segmented blank, remove the burrs and attachments on the blank, and then use fine sandpaper to polish the surface of the standard sample blank to increase the surface finish of the sample;

[0117] (9)Production applicability inspection,

[0118] Based on the average value of the measurement surfaces of 20 segmented blanks, as the measurement value of this standard sample blank, the measurement values of each element in the 20 segmented blanks can be obtained; calculate the standard deviation of the measurement values of the 20 segmented blanks, and compare the standard deviation with the production control range. If the standard deviation × 6 < production control range, it is applicable for production. The production applicability inspection form is as follows in Table 5;

[0119] Table 5 Production applicability inspection form

[0120]

[0121] (10) Constant value

[0122] Using known techniques, the standard values ​​and expanded uncertainties were obtained. The summary table of the set value data is shown in Table 6 below.

[0123] Table 6 Summary Table of Fixed Value Data

[0124]

[0125] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

[0126] The preferred embodiments and examples of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments and examples. For those skilled in the art, several improvements and modifications can be made without departing from the concept of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for sampling and preparing a nickel-iron molten metal spectral standard, characterized in that, Includes the following steps: 1) Design of standard chemical composition, Based on product standard requirements and actual product control needs, the chemical composition of the standard sample is precisely designed to meet the requirement that the composition of each element before furnace operation is similar to that of the finished product. The standard sample includes the following components by weight percentage: C: 2.8%-3.0%, Si: 0.9%-1.0%, S: 0.22%-0.25%, Cr: 1.9%-2.2%, Ni: 8.0%-9.0%; the balance is iron and impurities. 2) Nickel-iron smelting, Laterite nickel ore, limestone, and reducing agent are screened and crushed in the raw material yard and preparation room, then mixed and fed into a rotary kiln. The raw materials are dried, roasted, and pre-reduced to produce nickel slag at 1000℃, which is then smelted into molten nickel iron in a submerged arc furnace. 3) Assembly of the standard sample casting mold. The casting mold includes an upper mold, a bottom mold, and a bottom mold gasket. A through-flow casting cavity is provided within the upper mold. The bottom mold gasket is disposed within the bottom mold. The lower part of the upper mold can be inserted into the bottom mold, and the bottom mold gasket seals the bottom of the casting cavity. The upper mold includes several upper mold components, which are nested together sequentially from top to bottom. The casting cavity has a cylindrical structure. The upper mold, bottom mold, and bottom mold gasket are all made of copper. The assembly steps of the casting mold are as follows: first, install the bottom mold gasket in the insertion slot of the bottom mold; then, insert the bottom of one upper mold component into the insertion slot of the bottom mold. After insertion, the remaining upper mold components are nested and inserted into the upper parts of their corresponding upper mold components, thus completing the assembly of the casting mold. After assembly, the casting mold is placed vertically with the pouring gate at the top. The wall thickness of the upper mold components is between 35mm and 50mm. 4) Material collection, The molten nickel-iron is kept above 1500℃. It is then scooped out using a high-temperature resistant ceramic spoon and poured into the casting cavity of the mold. The casting mold is then allowed to cool naturally at an environment of 20℃-35℃ until it cools into a rod-shaped molten nickel-iron billet. After cooling and shaping, the mold is removed to obtain the standard sample billet. Depending on the requirements, multiple standard sample billets or a single standard sample billet may be obtained. Mark the top and bottom of the cylindrical standard blank, with the end furthest from the pouring gate being the bottom. After marking the top and bottom, cut off a small section from the top and bottom of the standard blank, and use the remaining part as the initial standard blank for subsequent applications. The volume of the high-temperature resistant ceramic spoon is between 500ml and 1000ml. After the standard blank has cooled, formed, and been demolded, cut and discard it at 50mm from the bottom and 40mm from the top. 5) Marking, When there are multiple standard sample blanks, the initial standard sample blanks are distinguished and marked according to the sampling order. After marking, each initial standard sample blank is evenly divided into multiple segments from bottom to top. When using a single standard sample blank, the standard sample blank is evenly cut into multiple segmented blanks from bottom to top, and each segmented blank is marked sequentially from bottom to top. When using multiple standard sample blanks, the initial standard sample blanks are numbered A, B, C, D, ... according to the sampling order. Each initial standard sample is evenly marked with 20 segments from bottom to top, with the marking numbers 01, 02, 03, ...

20. The top and bottom segments of each initial standard sample blank are marked on their end faces, so that the end face of the segment near the bottom of the initial standard sample blank contains "+", and the end face near the top of the initial standard sample blank contains "-". When using a single standard sample blank, the initial standard sample blank is evenly divided into 20 segments, with the marking numbers 01, 02, 03, ...

20. The end face of each segment is marked, so that the end face of the segment near the bottom of the initial standard sample blank contains "+", and the end face near the top of the initial standard sample blank contains "-". 6) Chemical composition segregation test, The C, Si, S, Cr, and Ni elements in the corresponding segmented billets were analyzed and tested using a spark source atomic emission spectrometer in accordance with the GB / T42794-2023 method. The initial standard sample blanks were tested using the analytical test data. The rules were as follows: (1) When there are multiple standard sample blanks, the top and bottom segments of each initial standard sample blank were taken according to the original multi-segment division marks of the initial standard sample blank. The remaining part after the top and bottom segments of the initial standard sample blank were removed was the final standard sample blank; (2) When there is a single standard sample blank, all segments were taken; (3) The measurement surface of each segment blank was marked with the position of the circumscribed vertex of the regular polygon to determine the excitation measurement position. The average value of the excitation measurement position of each mark was measured multiple times and used as the basic data for the Grubbs test and F test. When using multiple standard billet samples, the end face of the bottom segment billet marked with "01+" is used as the excitation test surface, and the end face of the top segment billet marked with "20+" is used as the excitation test surface. At least three excitation positions are evenly marked on the corresponding excitation test surface of each segment billet. During the excitation test, 2-3 excitations are performed at each excitation position. The average value of the measurements after multiple excitations at each excitation position is used as the basic data for the test. The average measurement results of the top and bottom segments of each initial standard sample billet are used as two measurement values ​​for each standard sample billet. The Grubbs test is used to remove outlier final standard sample billets. After removing outlier final standard sample billets, the average measurement values ​​of different positions of the top and bottom segments of the same initial standard sample billet are used as the data within the group. The average value of the measurement results of the top and bottom segments of each initial standard sample blank is used as the inter-group data, and the F test is used to determine the uniformity of each final standard sample blank. When testing a single standard billet, the end faces of each segmented billet marked with "+" are used as the excitation test surfaces. At least three excitation positions are uniformly marked within the excitation test surfaces of all segmented billets. During the excitation test, 2-3 excitations are performed at each excitation position. The average value of the measurements after multiple excitations at each excitation position is used as the basic data for the test. The average value of the measurements at different excitation positions on the same measurement surface is used as the average value of the measurement surface. The Grubbs test is used to test the average value of each measurement surface in the standard billet. If the statistical results are abnormal, a new standard billet is taken. If no abnormalities are found in the statistical results, the measurements at different excitation positions on the same measurement surface are used as the within-group data. The average value of each measurement surface is used as the between-group data. The F-test is used to determine the uniformity of the single standard billet. The uniformity test data of this test is used as the final uniformity test data for the single standard billet. 7) Physical segregation test, After passing the chemical composition segregation test, the physical segregation test shall be carried out according to the following rules: (1) When there are multiple standard sample billets: the excitation detection surfaces of the bottom and top sections of each initial standard sample billet shall be used as the physical segregation test surfaces and sent for physical low magnification microstructure test; (2) When there is a single standard sample billet: the excitation detection surfaces of the bottom, middle and top sections of the standard sample billet shall be used as the physical segregation test surfaces and sent for physical low magnification microstructure test. 8) Sample processing, S1. Rough grinding; The rough grinding method is to use a grinding wheel to grind the outer surface of the blank to remove burrs and attachments from the surface of the blank; when there are multiple standard blanks, rough grinding is performed on each final standard blank; when there is a single standard blank, rough grinding is performed on each segment of the blank. S2. Fine grinding; The fine grinding method is to use fine sandpaper to grind the surface of the blank to increase the smoothness of the blank surface; when there are multiple standard blanks, fine grinding is performed on each final standard blank section; when there is a single standard blank, fine grinding is performed on each section of the blank. S3. Cutting and segmenting; This step is only implemented when there are multiple standard sample blanks. The implementation method is as follows: mark each final standard sample blank with multiple equally spaced segments, and divide the final standard sample blank from each mark. 9) Sampling inspection of standard sample homogeneity. The uniformity test of a single standard sample billet has been completed in step 6) above, so there is no need to perform a sampling inspection of the uniformity of a single standard sample billet in this step. When multiple standard billet samples are used, randomly select segmented billets and inspect them according to the GB / T42794-2023 method. Use a spark source atomic emission spectrometer to test the uniformity of elements that need to be determined. The random sampling rules are as follows: (1) Multiple standard blanks are arranged horizontally from top to bottom according to the initial sampling mark order. A sampling position is taken at a fixed distance. A certain number of segmented blanks are taken from each column according to the known sampling ratio. (2) The measured surface of the extracted segmented blanks is marked with multiple excitation positions according to the position of the circumscribed vertex of the regular polygon. The excitation position of each mark is measured multiple times and the average value is taken as the basic data for uniformity test. (3) The measured values ​​of different positions on the same measured surface of each segmented blank are taken as the data within the group. The average value of each measured surface is taken as the data between the groups. The uniformity of the standard blanks is tested by the F uniformity test method. If the statistical results are abnormal, the standard blanks are taken again. 10) Production suitability check, When using multiple standard sample billets, the production suitability check is performed on the measured values ​​of the randomly sampled segmented billets in step 9). When using a single standard sample billet, the production suitability check is performed on the measured values ​​of each segmented billet obtained in step 6. Specifically, the average measured value of the measured surface of each segmented billet is taken as the measured value of that segmented billet. The standard deviation of the measured value is calculated, and the standard deviation is compared with the production control range. If the standard deviation × 6 < the production control range, then it is suitable for production. 11) Constant value, The standard value and expanded uncertainty are obtained by setting the value of the segmented billet according to the existing known setting method.

2. The method for sampling and preparing a nickel-iron molten metal spectral standard according to claim 1, characterized in that, When using multiple standard blanks, the end face of the bottom section blank marked with "01+" is used as the physical segregation detection surface, and the end face of the top section blank marked with "20+" is used as the physical segregation detection surface. After the physical segregation inspection surface is determined, it is processed by a milling machine and then sent for physical low-magnification microstructure inspection. When using a single standard sample billet, the top, middle, and bottom segments of the initial standard sample billet are used as test billets. Simultaneously, the end face of the top segment billet marked with "01+" is used as the physical segregation detection surface; the end face of the bottom segment billet marked with "20+" is used as the physical segregation inspection surface; and the end face of the middle segment billet marked with "10+" is used as the physical segregation inspection surface. After the physical segregation inspection surfaces are determined, they are processed by a milling machine and then sent for physical low-magnification microstructure inspection.

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