阅读说明：本技术 一种低合金铸铁光谱成套标准样品及其制备方法和检测方法 (Low-alloy cast iron spectrum complete standard sample and preparation method and detection method thereof ) 是由 刘鹏 张增坤 梁红艳 于 2021-08-20 设计创作，主要内容包括：本发明涉及光谱标准样品制备技术领域,尤其是涉及一种低合金铸铁光谱成套标准样品及其制备方法和检测方法,包括化学成分的设计,冶炼,成型,标准样品的处理及制备,标准样品初检,单元内检验,块间均匀性检验,定值分析及标准值确定,稳定性检验,成线性考察。通过本发明的方法制备得到的标准样品使用范围广,样品均匀性好,样品中夹杂物含量低,样品白口化彻底,且样品具有长期稳定性,成线性良好的特征,具有广阔的应用前景。(The invention relates to the technical field of spectrum standard sample preparation, in particular to a complete set of low-alloy cast iron spectrum standard sample and a preparation method and a detection method thereof. The standard sample prepared by the method has the characteristics of wide application range, good sample uniformity, low impurity content in the sample, thorough white sample, long-term stability, good linearity and wide application prospect.)

1. The preparation method of the low-alloy cast iron spectrum standard sample is characterized by comprising the following steps of:

(a) designing chemical components: the chemical components consist of the following components: c, Si, Mn, P, S, Cr, Ni, Mo, V, Cu, Mg, Ti, B, Al, As, W, Nb, Sb, Pb, Sn, La, Ce;

preferably, in the step (a), 6-8 horizontal chemical components are designed within a specified chemical component range according to the principle of the minimum probability of producing inclusions and the principle of equal gradient distribution, mutual interference among elements and the minimum probability of producing inclusions;

(b) smelting: designing and preparing raw materials according to the chemical components in the step (a), and smelting the prepared raw materials in a medium-frequency induction furnace at the smelting temperature of 1200-1600 ℃ for 1-6 h;

(c) molding: casting the sample smelted in the step (b) in a mould at the temperature of 1300-1450 ℃ for 1-60 s at the speed of 0.24-10 t/h to complete crystallization, and obtaining a crude sample, wherein the modulus ratio of the casting is 0.2-1 cm; the modulus ratio is volume/surface area;

(d) treatment and preparation of standard samples: and (3) quenching and tempering the coarse sample, and performing linear cutting on the treated sample to obtain a finished product block standard sample.

2. The method for preparing the standard sample of the low-alloy cast iron spectrum according to claim 1, wherein in the step (a), the chemical composition comprises the following components in percentage by weight: 2.1 to 3.9 percent of C, 0.5 to 3.8 percent of Si, 0.1 to 1.7 percent of Mn, 0.01 to 0.5 percent of P, 0.005 to 0.06 percent of S, 0.1 to 2.3 percent of Cr0, 0.01 to 2.2 percent of Ni0, 0.02 to 0.8 percent of Mo0.02, 0.02 to 0.6 percent of V, 0.05 to 1.2 percent of Cu0.0001 to 0.09 percent of Mg0.0001 to 0.3 percent of Ti0.005 to 0.3 percent of B, 0.002 to 0.3 percent of B, 0.001 to 0.8 percent of Al, 0.002 to 0.15 percent of As0.002 to 0.15 percent of W, less than or equal to 0.6 percent of Nb, less than or equal to 0.05 percent of Sb0.004 to 0.1 percent of Pb0.0002 to 0.08 percent of B, 0.002 to 0.3 percent of Sn0.3 percent of La and Ce are residual;

preferably, in the step (a), 7 horizontal chemical compositions are designed within a specified chemical composition range according to the principle of the minimum gradient distribution, the minimum interference among elements and the minimum probability of generating inclusions;

preferably, in the step (a), in a specified chemical composition range, the 7 horizontal chemical compositions designed according to the principle of the equal gradient distribution, the mutual interference among elements and the lowest probability of generating inclusions are specifically: (1) 3.35 to 3.5 percent of C, 0.54 to 0.65 percent of Si, 0.18 to 0.22 percent of Mn, 0.065 to 0.075 percent of P, 0.05 to 0.06 percent of S, 2.15 to 2.25 percent of Cr2, 0.01 to 0.06 percent of Ni0.01 to 0.06 percent of Mo0.70 to 0.75 percent of V, 0.5 to 0.6 percent of V, 0.40 to 0.45 percent of Cu0.0001 to 0.002 percent of Mg0.0001 to 0.002 percent of Ti0.005 to 0.019 percent of B, 0.015 to 0.020 percent of B, 0.001 to 0.002 percent of Al, 0.018 to 0.025 percent of As0.018 to 0.025 percent of W, 0.5 to 0.6 percent of Nb0.003 to 0.005 percent of Sb0.025 to 0.046 percent of Pb0.073 percent of Sn, 0.030 to 0.040 percent of La and Ce are residual; (2) 3.10 to 3.15 percent of C, 2.45 to 2.55 percent of Si, 0.76 to 0.85 percent of Mn, 0.40 to 0.45 percent of P, 0.005 to 0.011 percent of S, 1.5 to 1.6 percent of Cr1, 0.95 to 1.01 percent of Ni0.55 to 0.60 percent of Mo0.20 to 0.27 percent of V, 1.10 to 1.20 percent of Cu1, 0.060 to 0.070 percent of Mg0.15 to 0.20 percent of Ti0.15 to 0.20 percent of B, 0.20 to 0.28 percent of Al, 0.013 to 0.017 percent of As0.008 to 0.012 percent of W, 0.14 to 0.20 percent of Nb0.04 to 0.05 percent of Sb0.035 to 0.050 percent of Pb0.014 to 0.025 percent of Sn0.10 to 0.13 percent of La and Ce, and the residual amount of La and Ce; (3) 2.85 to 2.95 percent of C, 1.50 to 1.65 percent of Si, 0.95 to 1.00 percent of Mn, 0.20 to 0.25 percent of P, 0. 0.0099 to 0.015 percent of S, 0.95 to 1.05 percent of Cr0, 0.50 to 0.55 percent of Ni0.50, 0.40 to 0.45 percent of Mo0.18 to 0.22 percent of V, 0.70 to 0.80 percent of Cu0.80 percent of Mg0.040 to 0.050 percent of Ti, 0.055 to 0.065 percent of B, 0.09 to 0.12 percent of B, 0.008 to 0.016 percent of Al, 0.022 to 0.030 percent of As0.03 to 0.05 percent of W, 0.03 to 0.04 percent of Nb0.075 to 0.085 percent of W, 0.010 to 0.017 percent of Pb0.085 percent of Sn, and La and Ce are residual; (4) 3.55 to 3.65 percent of C, 2.05 to 3.15 percent of Si, 1.20 to 1.30 percent of Mn, 0.14 to 0.17 percent of P, 0.043 to 0.050 percent of S, 1.15 to 1.25 percent of Cr, 0.7 to 0.8 percent of Ni, 0.27 to 0.33 percent of Mo0.30 to 0.36 percent of V, 0.50 to 0.55 percent of Cu0.008 to 0.012 percent of Mg0.008 to 0.012 percent of Ti0.045 to 0.055 percent of B, 0.055 to 0.072 percent of Al, 0.065 to 0.070 percent of As0.065 to 0.070 percent of W, 0.25 to 0.30 percent of Nb0.02 to 0.03 percent of Sb0.045 to 0.055 percent of Pb0.003 to 0.010 percent of Sn, 0.20 to 0.30 percent of La and Ce are residual; (5) 3.80-3.90 percent of C, 0.95-1.30 percent of Si, 1.40-1.55 percent of Mn, 0.27-0.35 percent of P, 0.011-0.020 percent of S, 0.60-0.70 percent of Cr0.40-1.50 percent of Ni1.40, 0.17-0.23 percent of Mo0.17-0.23 percent of V, 0.15-0.20 percent of V, 0.27-0.33 percent of Cu0.27, 0.025-0.035 percent of Mg0.035 percent, 0.048-0.075 percent of Ti0.025-0.035 percent of B, 0.25-0.32 percent of Al, 0.035-0.045 percent of As0.035, 0.08-0.12 percent of W, less than or equal to 0.0016 percent of Nb, 0.085-0.095 percent of Sb0.030-0.035 percent of Pb0.035 percent, 0.0102-0.06 percent of Sn0.06 percent of La and Ce are residual; (6) 2.10 to 2.20 percent of C, 3.47 to 3.80 percent of Si, 1.60 to 1.70 percent of Mn, 0.070 to 0.090 percent of P, 0.008 to 0.015 percent of S, 0.40 to 0.50 percent of Cr0, 2.0 to 2.2 percent of Ni2, 0.07 to 0.13 percent of Mo0.40 to 0.45 percent of V, 0.05 to 0.10 percent of Cu0.015 percent of Mg, 0.020 percent of Ti0.10 to 0.15 percent of Ti, 0.005 to 0.0083 percent of B, 0.50 to 0.602 percent of Al, 0.09 to 0.11 percent of As0.30 to 0.45 percent of W, 0.002 to 0.012 percent of Nb0.053 to 0.065 percent of Pb0.045 to 0.061 percent of Sn, 0.070 to 0.080 percent of La and residual Ce; (7) 3.40 to 3.55 percent of C, 2.30 to 2.40 percent of Si, 0.60 to 0.70 percent of Mn, 0.01 to 0.02 percent of P, 0.005 to 0.01 percent of S, 0.1 to 0.2 percent of Cr0, 0.01 to 0.2 percent of Ni0.01 to 0.2 percent of Mo, 0.02 to 0.05 percent of V, 0.02 to 0.05 percent of Cu, 0.15 to 0.20 percent of Cu, 0.080 to 0.090 percent of Mg0.015 to 0.023 percent of Ti, 0.002 to 0.004 percent of B, 0.005 to 0.011 percent of Al, 0.002 to 0.005 percent of As0, less than or equal to 0.005 percent of W, less than or equal to 0.001 percent of Nb, 0.0048 to 0.006 percent of Sb0.0006 to 0.005 percent of Pb0.002 to 0.005 percent of Sn, and the residual amount of La and Ce.

3. The method for preparing the standard sample of the low-alloy cast iron spectrum according to the claim 1 or 2, characterized in that in the step (b), before smelting, the raw materials are selected by inspection and cleaned by adopting sand blasting and machining methods to remove surface scale and dirt;

preferably, in the step (b), the smelting temperature is 1400-1550 ℃, and the smelting time is 2-3 h;

preferably, in the step (b), in the smelting process, for the easily-oxidized elements, the optimal adding conditions are selected; further preferably, the easily oxidizable element includes a magnesium element, a rare earth metal element, an aluminum element, a manganese element, and a silicon element; the optimal adding conditions are as follows: adding an aluminum element and an alloy thereof before casting, adding a magnesium element and an alloy thereof, a rare earth metal element and an alloy thereof in a casting ladle for protection, and adding a silicon element and an alloy thereof, a manganese element and an alloy thereof in the later stage of complete melting down of the rest metals;

preferably, in the step (c), 0.1kg to 0.5kg of tellurium metal, 0.05kg to 0.2kg of magnesium metal or 0.5kg to 5kg of chromium metal is added into the molten iron before casting; further preferably, in the step (c), 0.1kg to 0.5kg of tellurium metal is added into the molten iron before casting;

preferably, in the step (c), the casting speed is 1 t/h-5 t/h;

preferably, in the step (c), the modulus ratio of the casting is 0.4 cm-0.6 cm;

preferably, in the step (c), the mold is capable of making nonmetallic inclusions in molten iron aggregate on the surface of the sample;

preferably, in the step (c), the material of the mold includes a cast iron material, a water-cooled copper alloy material, graphite and a mica material.

4. The method for preparing the standard spectrum sample of the low-alloy cast iron according to claim 3, wherein in the step (d), the temperature for quenching and tempering is 500-600 ℃, and the holding time is 2-20 h;

preferably, in the step (d), the temperature of the thermal refining is 500-550 ℃, and the heat preservation time is 2-8 h;

preferably, in the step (d), the size of the block sample of the wire-electrode cutting is 35mm × 30 mm.

5. A low alloy cast iron spectral standard prepared according to the method of any one of claims 1 to 4.

6. The method for detecting the standard sample according to claim 5, comprising the steps of:

(e) initial detection of a standard sample: performing internal defect inspection on the standard sample by using an ultrasonic flaw detector with the resolution of 0.5dB, and performing whitening inspection on the standard sample by using a metallographic microscope;

(f) and (3) in-unit inspection: cutting the standard sample into 7 pieces by adopting linear cutting, exciting 6 points at the radius 1/2 in the bottom surface direction of each piece with the same central angle, randomizing 7 multiplied by 6 excitation points, and counting by a pairwise comparison method according to variance analysis;

(g) and (3) checking the uniformity among blocks: randomly exciting three points on a standard sample by using a spectrometer, and detecting the significance of the blocks relative to the precision in the blocks by using a single-factor variance analysis method;

(h) and (3) fixed value analysis and standard value determination: randomly drawing ten finished massive standard samples from each of the 7 levels, processing the ten finished massive standard samples into a crumb shape to obtain crumb-shaped chemical samples with the weight of 1.5kg, and fully and uniformly mixing the crumb-shaped chemical samples for analysis and value determination; analyzing the normality, abnormal value and equal precision of the average value of the data, and determining a standard value, wherein the standard value is the total average value of each fixed value data;

(i) and (3) stability test: testing the sample by adopting a spark discharge atomic emission spectrometry for 1-3 times every year;

(j) linear investigation: and sequentially exciting the standard sample on the spark discharge atomic emission spectrometer, exciting for 3-6 times to obtain the light intensity value of each element, and establishing a linear relation between the average value of the light intensity values and the corresponding standard value.

7. The method for testing a standard sample according to claim 6, wherein in the step (e), five samples are taken from the initial and final coagulation sites of each horizontal standard sample, the internal defects of the samples are inspected by an ultrasonic flaw detector having a resolution of 0.5dB, and after the initial inspection is passed, ultrasonic flaw detection is performed on each sample;

preferably, in the step (e), five samples are randomly taken from each horizontal standard sample, and the two end faces and the whitening of the 1/2 cross section of the samples are examined by a metallographic microscope at a magnification of 100 times;

preferably, in the step (e), the etching solution used for the sample for metallographic microscope detection is a 4% nitric acid alcoholic solution.

8. The method for detecting a standard sample according to claim 6, wherein in the step (f), five samples are extracted from the last coagulation part in each horizontal standard sample, each sample is cut into 7 pieces from bottom to top at equal intervals by using a line, 6 points are excited at equal central angles at a radius 1/2 in the direction of the bottom surface of each piece, and after 7 x 6 excitation points are randomized, statistics is performed according to a variance analysis pairwise comparison method;

preferably, in the step (f), a piece is cut by linear cutting from bottom to top at different depths in sequence to form 7 surfaces, and the surface is marked as-1 mm surface, -3mm surface, -5mm surface, -10mm surface, -15mm surface, -20mm surface and-25 mm surface in sequence by taking the bottom surface direction as an excitation surface;

preferably, in the step (f), the maximum difference of the average values of the elements between any two of the extracted samples is less than or equal to a critical value.

9. The method for detecting the standard sample according to claim 6, wherein in the step (g), 10-20 blocks of each horizontal standard sample are extracted, three points are randomly excited in each block on an ARL3460 direct-reading spectrometer, and the significance between the blocks relative to the precision in the blocks is checked by adopting a one-factor analysis of variance method;

preferably, in the step (g), when the statistic F is not greater than the critical value and the non-uniformity is not greater than 0.3 times the standard uncertainty, the inter-block is uniform.

10. The method for detecting a standard sample according to claim 6, wherein in the step (i), the test result is tested as follows:

if | x_CRM-x_mean| < U, whereinThe stability is good;

in the formula x_CRMIs a characteristic value of a standard sample, u_CRMAs an uncertainty on the CRM certificate; x is the number of_meanFor measured observations u_meanFor measurement uncertainty, k is the spreading factor;

preferably, at a 95% confidence probability, k ═ 2;

preferably, in the step (j), when the linear correlation coefficient r is greater than 0.98, the linearity of the set of standard samples is proved to be good;

the calculation formula of r is as follows:

wherein, C_iIs the standard content of each point and is,is the average value of the contents of each point, I_iThe light intensity or light intensity ratio of the corresponding content of each point,the average value of the light intensity or the light intensity ratio of each point.

Technical Field

The invention relates to the technical field of spectrum standard sample preparation, in particular to a low-alloy cast iron spectrum complete set standard sample and a preparation method and a detection method thereof.

Background

With the rapid development of the industries of automobiles and metallurgical machinery, people have wider and wider application range of low-alloy cast iron materials, higher and higher quality requirements and more chemical component control quantity.

Cast iron can be divided into: gray cast iron, white cast iron, malleable cast iron, nodular cast iron, vermicular cast iron, and alloyed cast iron. The alloy cast iron is cast iron with special properties by adding alloy elements into common cast iron. The alloy cast iron is divided into low-alloy cast iron (the content of alloy elements is less than 5%), medium-alloy cast iron (the content of alloy elements is 5-10%) and high-alloy cast iron (the content of alloy elements is more than 10%) according to the adding amount of the alloy elements. The standard sample is used for quality control in the production process of the cast iron product. A standard sample is a material of one or more defined characteristics that is sufficiently uniform and stable that it has been determined to be compatible with the intended use of the measurement process.

Although many standard samples exist in the prior art, the existing standard samples contain less chemical components, and can only cover one, two or three of the cast irons, so that the application range is smaller, most of the standard samples are produced by self and rarely sold to the outside, and the preparation method of the standard samples sold to the outside at present is generally not disclosed. Meanwhile, the existing low-alloy cast iron standard sample is difficult to realize complete white cast due to high carbon content and impurity content, so that spectral excitation is influenced, and the analysis data is inaccurate and unstable. In addition, in the prior art, the material is in a metastable state in the whitening process during sample preparation, so that the long-term stability of the standard sample is reduced, and the long-term use requirement of a user cannot be met.

In view of the above, there is a need for a new method for preparing a standard sample, a standard sample prepared by the method, and a method for detecting the standard sample.

Disclosure of Invention

The invention aims to provide a preparation method of a complete set of low-alloy cast iron spectrum standard sample, which aims to solve the technical problems that the low-alloy cast iron material standard sample in the prior art is low in covered chemical components, high in carbon content and high in inclusion content, and is difficult to form white spots.

The second purpose of the invention is to provide a standard sample prepared by the method for preparing the complete set of low-alloy cast iron spectrum standard sample.

The third purpose of the invention is to provide a method for detecting the standard sample prepared by the method for preparing the complete set of low-alloy cast iron spectrum standard sample, so that the white melting of the standard sample is ensured, the inclusion content in the sample is monitored, and the uniformity, stability and linearity of the sample are ensured to be good.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

in a first aspect, the invention provides a preparation method of a complete set of low-alloy cast iron spectrum standard samples, which comprises the following steps:

(a) designing chemical components: the chemical components consist of the following components: c, Si, Mn, P, S, Cr, Ni, Mo, V, Cu, Mg, Ti, B, Al, As, W, Nb, Sb, Pb, Sn, La, Ce;

preferably, in the step (a), the chemical composition consists of the following components in percentage by weight: 2.1 to 3.9 percent of C, 0.5 to 3.8 percent of Si, 0.1 to 1.7 percent of Mn, 0.01 to 0.5 percent of P, 0.005 to 0.06 percent of S, 0.1 to 2.3 percent of Cr0, 0.01 to 2.2 percent of Ni0, 0.02 to 0.8 percent of Mo0.02, 0.02 to 0.6 percent of V, 0.05 to 1.2 percent of Cu0.0001 to 0.09 percent of Mg0.0001 to 0.3 percent of Ti0.005 to 0.3 percent of B, 0.002 to 0.3 percent of B, 0.001 to 0.8 percent of Al, 0.002 to 0.15 percent of As0.002 to 0.15 percent of W, less than or equal to 0.6 percent of Nb, less than or equal to 0.05 percent of Sb0.004 to 0.1 percent of Pb0.0002 to 0.08 percent of B, 0.002 to 0.3 percent of Sn0.3 percent of La and Ce are residual;

preferably, in the step (a), 6-8 horizontal chemical components are designed within a specified chemical component range according to the principle of the minimum probability of producing inclusions and the principle of equal gradient distribution, mutual interference among elements and the minimum probability of producing inclusions;

preferably, in the step (a), 7 horizontal chemical compositions are designed within a specified chemical composition range according to the principle of the minimum gradient distribution, the minimum mutual interference among elements and the minimum probability of generating inclusions.

(b) Smelting: designing and preparing raw materials according to the chemical components in the step (a), and smelting the prepared raw materials in a medium-frequency induction furnace at the smelting temperature of 1200-1600 ℃ for 1-6 h;

preferably, in the step (b), before smelting, the raw materials are inspected, selected and cleaned to form surface oxide scales and dirt;

preferably, in the step (b), the smelting temperature is 1400-1550 ℃, and the smelting time is 2-3 h;

preferably, in the step (b), in the smelting process, for the easily-oxidized elements, the optimal adding conditions are selected; further preferably, the easily oxidizable element includes a magnesium element, a rare earth metal element, an aluminum element, a manganese element, and a silicon element; the optimal adding conditions are as follows: the aluminum element and the alloy thereof are added before casting, the magnesium element and the alloy thereof, the rare earth metal element and the alloy thereof are put in a casting ladle for protection, and the silicon element and the alloy thereof, the manganese element and the alloy thereof are added in the later stage of complete melting down of the rest metals.

(c) Molding: casting the sample smelted in the step (b) in a mould at the temperature of 1300-1450 ℃ for 1-60 s at the speed of 0.24-10 t/h to complete crystallization, and obtaining a crude sample, wherein the modulus ratio of the casting is 0.2-1 cm; the modulus ratio is volume/surface area;

preferably, in the step (c), 0.1kg to 0.5kg of tellurium metal, 0.05kg to 0.2kg of magnesium metal or 0.5kg to 5kg of chromium metal is added into the molten iron before casting;

preferably, in the step (c), 0.1kg to 0.5kg of tellurium metal is added into the molten iron before casting;

preferably, in the step (c), the mold is capable of making nonmetallic inclusions in molten iron aggregate on the surface of the sample;

preferably, in the step (c), the material of the mold includes a cast iron material, a water-cooled copper alloy material, graphite and a mica material.

(d) Treatment and preparation of standard samples: quenching and tempering the crude sample, and performing linear cutting on the treated sample to obtain a finished product blocky standard sample;

preferably, in the step (d), the temperature of the thermal refining is 500-600 ℃, the heat preservation time is 2-10 h, the initial temperature of furnace cooling is the finishing temperature of the thermal refining, and the time of the furnace cooling is the time when the temperature in the furnace reaches the room temperature after the furnace door is opened;

preferably, in the step (d), the temperature of the thermal refining is 500-550 ℃, and the heat preservation time is 2-8 h;

preferably, in the step (d), the size of the block sample of the wire-electrode cutting is 35mm × 30 mm.

In a second aspect, the invention provides a standard sample prepared by the preparation method of the low-alloy cast iron spectrum complete set of standard samples.

In a third aspect, the invention provides a method for detecting a standard sample prepared by a preparation method of a low-alloy cast iron spectrum standard sample, which comprises the following steps:

(e) initial detection of a standard sample: performing internal defect inspection on the standard sample by using an ultrasonic flaw detector with the resolution of 0.5dB, and performing whitening inspection on the standard sample by using a metallographic microscope;

preferably, in the step (e), five samples are extracted from the initial and final solidification parts of each horizontal standard sample, the internal defects of the samples are detected by an ultrasonic flaw detector with the resolution of 0.5dB, and after the initial detection is qualified, ultrasonic flaw detection is carried out on each sample;

preferably, in the step (e), five samples are randomly taken from each horizontal standard sample, and the two end faces and the whitening of the 1/2 cross section of the samples are examined by a metallographic microscope at a magnification of 100 times;

preferably, in the step (e), the etching solution used for the sample for metallographic microscope detection is a 4% nitric acid alcoholic solution.

(f) And (3) in-unit inspection: cutting the standard sample into 7 pieces by adopting linear cutting, exciting 6 points at the radius 1/2 in the bottom surface direction of each piece with the same central angle, randomizing 7 multiplied by 6 excitation points, and counting by a pairwise comparison method according to variance analysis;

preferably, in the step (f), five samples are extracted from the last coagulation part in each horizontal standard sample, each sample is cut into 7 pieces from bottom to top at equal intervals by adopting a line, the radius 1/2 in the bottom surface direction of each piece is equal to the excitation point of the central angle of 6 points, and after 7 multiplied by 6 excitation points are randomized, statistics is carried out according to a pairwise comparison method of variance analysis;

preferably, in the step (f), a piece is cut by linear cutting from bottom to top at different depths in sequence to form 7 surfaces, and the surface is marked as-1 mm surface, -3mm surface, -5mm surface, -10mm surface, -15mm surface, -20mm surface and-25 mm surface in sequence by taking the bottom surface direction as an excitation surface;

preferably, in the step (f), the maximum difference of the average values of the elements between any two of the extracted samples is less than or equal to a critical value.

(g) And (3) checking the uniformity among blocks: randomly exciting three points on a standard sample by using a spectrometer, and detecting the significance of the blocks relative to the precision in the blocks by using a single-factor variance analysis method;

preferably, in the step (g), 10-20 blocks of each horizontal standard sample are extracted, three points are randomly excited by each block on an ARL3460 direct-reading spectrometer, and the significance of the blocks relative to the precision in the blocks is checked by adopting a one-factor analysis of variance method;

preferably, the inter-block is uniform when the statistic F is not greater than the threshold and the non-uniformity is not greater than 0.3 times the standard uncertainty.

(h) And (3) fixed value analysis and standard value determination: randomly drawing ten finished massive standard samples from each of 7 levels, processing the ten finished massive standard samples into a crumb shape to obtain crumb-shaped chemical samples with the weight of 1.5kg, and fully and uniformly mixing the crumb-shaped chemical samples for analysis and value determination; and analyzing the normality, abnormal value and equal precision of the average value of the data, and determining a standard value, wherein the standard value is the total average value of each fixed value data.

(i) And (3) stability test: testing the sample by adopting a spark discharge atomic emission spectrometry for 1-3 times every year;

preferably, in step (i), the test result is verified as follows:

if | x_CRM-x_mean| < U, whereinThe stability is good;

in the formula x_CRMIs a characteristic value of a standard sample, u_CRMAs an uncertainty on the CRM certificate; x is the number of_meanFor measured observations u_meanFor measurement uncertainty, k is the spreading factor;

preferably, in step (i), k is 2 with a 95% confidence probability.

(j) Linear investigation: sequentially exciting the standard sample on a spark discharge atomic emission spectrometer, exciting for 3-6 times to obtain light intensity values of each element, and establishing a linear relation between the average value of the light intensity values and the corresponding standard value;

preferably, in the step (j), when the linear correlation coefficient r is greater than 0.98, the linearity of the set of standard samples is proved to be good;

the calculation formula of r is as follows:

wherein, C_iIs the standard content of each point and is,is the average value of the contents of each point, I_iThe light intensity or light intensity ratio of the corresponding content of each point,the average value of the light intensity or the light intensity ratio of each point.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the preparation method of the complete set of low-alloy cast iron spectrum standard sample, the standard sample covers over 90% of the product range of the existing cast iron in design, so that the application range of the sample is wider; and in the aspect of component design, the minimum inclusion in the sample is ensured, and the uniformity of the sample is optimized.

(2) According to the invention, through a specific smelting and forming mode, the modulus ratio of the standard sample molds with different components is accurately calculated, and the whitening element is added, so that the whitening of the standard sample of the cast iron material is more thorough, and the excitability of the sample is further improved.

(3) According to the invention, the standard sample is processed and prepared through quenching and tempering, so that the internal stress and the processing stress of the metastable material standard sample such as white cast iron are reduced, the excitation strength value is increased, and the long-term stability of the material is improved.

(4) The invention ensures the monomer quality of the standard sample by a unique unit internal inspection mode; by means of randomization of the excitation sequence of the in-cell inspection and uniformity inspection and the monitoring of drift, the system deviation caused by the drift of the spectrometer along with time is eliminated, and the real deviation in blocks and among blocks is reflected more objectively.

(5) The method adopts variance analysis and absolute parameter comparison method, and more accurately judges the uniformity qualification in units and between blocks.

(6) In linear inspection, the method adopts an evaluation mode of a correlation coefficient plus a standard error to more accurately reflect the applicability of the standard sample curve.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram of the position of the excitation point of a low-alloy cast iron standard sample provided by an embodiment of the invention.

Fig. 2 is a schematic diagram of the linear cutting depth of a low-alloy cast iron standard sample provided by the embodiment of the invention.

Fig. 3 is a metallographic microstructure image of a low-alloy cast iron standard sample provided by an embodiment of the invention.

Detailed Description

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and the detailed description, but those skilled in the art will understand that the following described embodiments are some, not all, of the embodiments of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The invention provides a preparation method of a complete set of low-alloy cast iron spectrum standard sample and an obtained standard sample, and the method comprises the following steps:

(a) the invention relates to chemical component design, which follows the following principle during component design: (1) the range of the components covers the upper limit and the lower limit of an analysis product, and the requirement of smelting in front of a product furnace is fully considered when the upper limit and the lower limit are prolonged; (2) the components of each element are designed to be uniformly distributed in a gradient manner as much as possible; (3) two elements which are easy to form inclusions are avoided in each point and exist in a high content; (4) note that the matrix is balanced.

The chemical component design and the subsequent smelting and forming process design are related, most of the existing standard samples contain few chemical components, and even if the samples containing many chemical components are designed, the prepared samples cannot be used as the standard samples due to the limitation of the preparation method. The invention improves the processes from chemical component design to smelting and molding, thereby obtaining a uniform and stable standard sample containing more chemical components.

In a specific embodiment of the invention, the chemical composition consists of: c, Si, Mn, P, S, Cr, Ni, Mo, V, Cu, Mg, Ti, B, Al, As, W, Nb, Sb, Pb, Sn, La, Ce;

in a specific embodiment of the invention, the chemical composition consists of the following components in percentage by weight: 2.1 to 3.9 percent of C, 0.5 to 3.8 percent of Si, 0.1 to 1.7 percent of Mn, 0.01 to 0.5 percent of P, 0.005 to 0.06 percent of S, 0.1 to 2.3 percent of Cr0, 0.01 to 2.2 percent of Ni0, 0.02 to 0.8 percent of Mo0.02, 0.02 to 0.6 percent of V, 0.05 to 1.2 percent of Cu0.0001 to 0.09 percent of Mg0.0001 to 0.3 percent of Ti0.005 to 0.3 percent of B, 0.002 to 0.3 percent of B, 0.001 to 0.8 percent of Al, 0.002 to 0.15 percent of As0.002 to 0.15 percent of W, less than or equal to 0.6 percent of Nb, less than or equal to 0.05 percent of Sb0.004 to 0.1 percent of Pb0.0002 to 0.08 percent of B, 0.002 to 0.3 percent of Sn0.3 percent of La and Ce are residual;

in a specific embodiment of the invention, the step (a) designs 6-8 horizontal chemical compositions within a specified chemical composition range according to the principle of equal gradient distribution, mutual interference among elements and lowest probability of generating inclusions;

in a specific embodiment of the invention, the step (a) designs 7 horizontal chemical compositions within a specified chemical composition range according to the principle of the minimum probability of producing inclusions and the principle of the equal gradient distribution and the mutual interference among elements; further, 7 designed horizontal chemical compositions are specifically shown in table 1:

TABLE 1 seven horizontal chemical composition design (w/%)

Serial number

C

Si

Mn

P

S

Cr

Ni

Mo

1

3.35～3.5

0.54～0.65

0.18～0.22

0.065～0.075

0.05～0.06

2.15～2.25

0.01～0.06

0.70～0.75

2

3.10～3.15

2.45～2.55

0.76～0.85

0.40～0.45

0.005～0.011

1.50～1.60

0.95～1.01

0.55～0.60

3

2.85～2.95

1.50～1.65

0.95～1.00

0.20～0.25

0.0099～0.015

0.95～1.05

0.50～0.55

0.40～0.45

4

3.55～3.65

2.05～3.15

1.20～1.30

0.14～0.17

0.043～0.050

1.15～1.25

0.70～0.80

0.27～0.33

5

3.80～3.90

0.95～1.30

1.40～1.55

0.27～0.35

0.011～0.020

0.60～0.70

1.40～1.50

0.17～0.23

6

2.10～2.20

3.47～3.8

1.60～1.70

0.070～0.090

0.008～0.015

0.40～0.50

2.00～2.20

0.07～0.13

7

3.40～3.55

2.30～2.40

0.60～0.70

0.01～0.02

0.005～0.01

0.1～0.2

0.01～0.2

0.02～0.05

Serial number

V

Cu

Mg

Ti

B

Al

As

W

1

0.50～0.60

0.40～0.45

0.0001～0.002

0.005～0.019

0.015～0.020

0.001～0.002

0.018～0.025

0.50～0.60

2

0.20～0.27

1.10～1.20

0.060～0.070

0.15～0.20

0.20～0.28

0.013～0.017

0.008～0.012

0.14～0.20

3

0.18～0.22

0.70～0.80

0.040～0.050

0.055～0.065

0.09～0.12

0.008～0.016

0.022～0.030

0.03～0.05

4

0.30～0.36

0.50～0.55

0.008～0.012

0.045～0.055

0.055～0.072

0.055～0.065

0.065～0.070

0.25～0.30

5

0.15～0.20

0.27～0.33

0.025～0.035

0.048～0.075

0.025～0.035

0.25～0.32

0.035～0.045

0.08～0.12

6

0.40～0.45

0.05～0.10

0.015～0.020

0.10～0.15

0.005～0.0083

0.50～0.602

0.09～0.11

0.30～0.45

7

0.02～0.05

0.15～0.20

0.080～0.090

0.015～0.023

0.002～0.004

0.005～0.011

0.002～0.005

≤0.005

Serial number

Nb

Sb

Pb

Sn

La

Ce

/

/

1

0.003～0.005

0.025～0.046

0.060～0.073

0.030～0.040

Residue of

Residue of

/

/

2

0.04～0.05

0.035～0.050

0.014～0.025

0.10～0.13

Residue of

Residue of

/

/

3

0.03～0.04

0.075～0.085

0.010～0.017

0.085～0.095

Residue of

Residue of

/

/

4

0.02～0.03

0.045～0.055

0.003～0.010

0.20～0.30

Residue of

Residue of

/

/

5

≤0.0016

0.085～0.095

0.030～0.035

0.0102～0.070

Residue of

Residue of

/

/

6

0.002～0.012

0.053～0.065

0.045～0.061

0.070～0.080

Residue of

Residue of

/

/

7

≤0.001

0.0048～0.006

0.0006～0.005

0.002～0.005

Residue of

Residue of

/

/

The standard sample covers more than 90% of the product range of the prior cast iron in design, solves the problem that the standard sample in the prior art can only cover one, two or two of gray cast iron, white cast iron, malleable cast iron, nodular cast iron, vermicular cast iron and alloy cast iron, so that the application range of the sample prepared by the method is wider; and in the aspect of component design, the minimum inclusion in the sample is ensured, and the uniformity of the sample is optimized.

(b) Smelting: designing and preparing raw materials according to the chemical components in the step (a), and smelting the prepared raw materials in a furnace at the smelting temperature of 1200-1600 ℃ for 1-6 h;

in a specific embodiment of the invention, the raw material prepared in the step (b) is placed in a medium-frequency induction furnace for smelting;

in a specific embodiment of the invention, the raw materials used in the step (b) are inspected, selected and cleaned of surface scale and dirt before smelting;

in a specific embodiment of the invention, in the step (b), the smelting temperature is 1400-1550 ℃, and the smelting time is 2-3 h;

in a specific embodiment of the present invention, in the step (b), in the smelting process, for the easily-oxidizable element, an optimal addition condition is selected; the easily oxidized elements comprise magnesium element, rare earth metal element, aluminum element, manganese element and silicon element; the optimal adding conditions are as follows: the aluminum element and the alloy thereof are added before casting, the magnesium element and the alloy thereof, the rare earth metal element and the alloy thereof are put in a casting ladle for protection, and the silicon element and the alloy thereof, the manganese element and the alloy thereof are added in the later stage of complete melting down of the rest metals.

In order to ensure the accuracy of smelting components, the components of the used raw materials are checked and selected, and the surface oxide skin and dirt are cleaned; the medium-frequency induction furnace is an induction furnace with the frequency within the range of 150-10000 Hz, is suitable for smelting non-ferrous metals such as steel, cast iron, copper, aluminum and the like and alloys thereof and preserving heat of liquid metal, has stronger adaptability to furnace materials, is suitable for intermittent operation, and has the advantages of high melting speed, high production efficiency, strong adaptability, flexible use, good electromagnetic stirring effect, convenient starting operation and the like. The invention utilizes the vortex stirring characteristic of the medium-frequency induction furnace to fully ensure the uniformity of the chemical components of the molten iron, and simultaneously selects the optimal adding condition for the easily oxidized element experiment in the smelting process, thereby ensuring the stable yield of different alloys and fully ensuring the design component target of the standard sample to be realized.

(c) Molding: casting the sample smelted in the step (b) in a mould at the temperature of 1300-1450 ℃ for 1-60 s at the speed of 0.24-10 t/h to complete crystallization, and obtaining a crude sample, wherein the modulus ratio of the casting is 0.2-1 cm; the modulus ratio is volume/surface area;

in a specific embodiment of the present invention, in the step (c), 0.1kg to 0.5kg of tellurium metal, 0.05kg to 0.2kg of magnesium metal, or 0.5kg to 5kg of chromium metal is added to the molten iron before casting;

in a specific embodiment of the present invention, 0.1kg to 0.5kg of tellurium metal is added to the molten iron before the step (c) of casting;

in a specific embodiment of the present invention, the mold in the step (c) is capable of making the non-metallic inclusions in the molten iron aggregate on the surface of the sample;

in a specific embodiment of the present invention, the material of the mold in the step (c) includes a cast iron material, a water-cooled copper alloy material, graphite, and a mica material.

The invention adopts the small enough modulus ratio and the proper temperature for fast pouring, so that the sample can be fast crystallized, the full white of the sample is fully ensured, the non-uniformity of the components of the sample caused by the sequential crystallization segregation is ensured to the maximum extent, and simultaneously, the specially designed mould can ensure that the non-metallic inclusion in the molten iron is concentrated on the surface of the sample for convenient processing and removal, thereby ensuring that the interior of the sample is purified.

The smelting and casting process of the invention not only ensures the uniformity of the molten iron components, but also ensures the requirement of obtaining the ideal design content, and in addition, can also maintain the content of impurities and gas in the casting in a lower range.

(d) Treatment and preparation of standard samples: quenching and tempering the crude sample, and performing linear cutting on the treated sample to obtain a finished product blocky standard sample;

in a specific embodiment of the invention, the temperature of the quenching and tempering in the step (d) is 500-600 ℃, the heat preservation time is 2-20 h, the initial temperature of furnace cooling is the quenching and tempering termination temperature, and the time of furnace cooling is the time when the temperature in the furnace reaches the room temperature after the furnace door is opened; further, the temperature of the quenching and tempering treatment in the step (d) is 500-550 ℃, and the heat preservation time is 2-8 h;

in a specific embodiment of the present invention, the size of the block sample for the wire-electrode cutting of the step (d) is phi 35mm x 30 mm; further, in the step (d), the sample is processed into a block sample with phi 35mm multiplied by 30mm by a cubic boron nitride ceramic tool lathe.

In the prior art, the microcrystallization treatment of the sample is very important because the sample tends to form coarse unstable structures during the whitening process, and the structures are easy to fracture and weaken excitability. The invention is carried out by a mode of quenching and tempering, wherein the quenching and tempering refers to a heat treatment method of high-temperature tempering after quenching. The material properties and the material quality can be adjusted to a great extent through tempering, and the material has good strength, plasticity and toughness and good comprehensive mechanical properties. The tempered sorbite is obtained after the thermal refining, is a tempered structure of martensite, is a mixture of ferrite and granular carbide, has basically no carbon supersaturation degree of the ferrite, is stable carbide and is a balanced structure at normal temperature. The invention can reduce the internal stress and the processing stress of the metastable material standard sample such as white cast iron and the like through proper quenching and tempering treatment, increase the excitation strength value and improve the long-term stability of the material.

The detection method of the standard sample prepared by the preparation method of the low-alloy cast iron spectrum standard sample comprises the following steps:

(e) the method comprises the following steps of (1) carrying out initial inspection on a standard sample, and observing whether the appearance of the sample has cracks or not and the defects of subcutaneous air holes through internal defect inspection; and (4) judging whether the sample contains free graphite and significant inclusions through white spot inspection.

In a specific embodiment of the present invention, the step (e) performs an internal defect inspection on the standard sample using an ultrasonic flaw detector (USN60 GE corporation) having a resolution of 0.5dB, and performs a whitening inspection on the standard sample using a metallographic microscope;

in a specific embodiment of the present invention, the step (e) extracts five samples from a portion of each horizontal standard sample where a defect is most likely to occur, inspects internal defects with an ultrasonic flaw detector having a resolution of 0.5dB, and performs ultrasonic flaw detection on each sample after the initial inspection is passed;

in a specific embodiment of the present invention, said step (e) randomly takes five samples from each horizontal standard sample, and inspects both end surfaces and whitening of 1/2 cross-section of the samples at a magnification of 100 times with a metallographic microscope;

in a specific embodiment of the present invention, the etching solution used for the sample in the step (e) for metallographic microscope examination is a 4% nital solution.

(f) And (3) in-unit inspection: cutting the standard sample into 7 pieces by adopting linear cutting, exciting 6 points at the radius 1/2 in the bottom surface direction of each piece with the same central angle, randomizing 7 multiplied by 6 excitation points, and counting by a pairwise comparison method according to variance analysis;

in a specific embodiment of the present invention, the step (f) of extracting five samples from each horizontal standard sample at a position where segregation is likely to occur, cutting each sample into 7 pieces from bottom to top at equal intervals by using a line, exciting 6 points at a radius 1/2 in the direction of the bottom surface of each piece at an equal central angle, randomizing 7 × 6 excitation points, and performing statistics according to a variance analysis pairwise comparison method, as shown in fig. 1;

in a specific embodiment of the invention, in the step (f), a piece is cut by linear cutting from bottom to top at different depths, and 7 surfaces are cut, and the bottom surface direction is taken as an excitation surface and is sequentially marked as a-1 mm surface, a-3 mm surface, a-5 mm surface, a-10 mm surface, a-15 mm surface, a-20 mm surface and a-25 mm surface, as shown in fig. 2;

in a specific embodiment of the present invention, the maximum difference between the average values of the elements between any two of the extracted samples is less than or equal to the critical value.

Generally, the uniformity of both ends of a standard sample is only considered in the prior art, and it is considered that the inner part is uniform if both ends are uniform enough. The applicant found that this idea is erroneous, since the central region of a casting is the region of the latest solidification, and examining only the homogeneity at the two ends is not representative of the overall homogeneity. The invention ensures the monomer quality of the standard sample through a unique in-unit inspection mode, randomizes each point excited in each plane into six measurement systems respectively in order to avoid the influence of system errors caused by instrument drift in the excitation process, and reflects the real deviation in the block more objectively. Meanwhile, the method of variance analysis and absolute parameter comparison is adopted to more accurately judge the uniformity in the unit, and if the maximum difference value of the average value of each element between any two pieces of all the extracted samples does not exceed a critical value, the consistency in the unit can be judged to be good.

(g) And (3) checking the uniformity among blocks: randomly exciting three points on a standard sample by using a spectrometer, and detecting the significance of the blocks relative to the precision in the blocks by using a single-factor variance analysis method;

in a specific embodiment of the invention, 10-20 blocks of each horizontal standard sample are extracted in the step (g), three points are randomly excited by each block on an ARL3460 direct-reading spectrometer, and the significance between the blocks relative to the precision in the blocks is checked by adopting a one-factor analysis of variance method;

in a specific embodiment of the present invention, the inter-block is uniform when the statistic F is not greater than the threshold and the non-uniformity is not greater than 0.3 times the standard uncertainty.

Wherein the content of the first and second substances,

when F is less than or equal to F_αThere was no significant difference between the variance between groups and within groups. When F is more than F_αThere was a significant difference in variance between groups and within groups.

The inhomogeneity of the samples was calculated as follows:

when the value of F is more than 1,

when F is less than or equal to 1,

when S is_bbWhen u is less than or equal to 0.3u (u represents the uncertainty of the target design of the composition), the uniformity of the elements in the sample is acceptable.

The conventional method in the prior art adopts a single-factor variance analysis method, and directly judges that the uniformity between blocks is qualified when the precision between the blocks is not significant relative to the precision in the blocks. This is not reasonable. Global uniformity between blocks is a relative concept that is closely related to the accuracy of the inspection method employed and the uniformity within a block or cell. If the inspection method is poor in accuracy or intra-block uniformity, it is easily misjudged to be uniform by the method. The method has the advantages that the single-factor variance analysis method is used for judging the significance of the blocks relative to the blocks, the qualitative judgment is carried out, and the final judgment is carried out by comparing the nonuniformity among the blocks with the target nonuniformity of 0.3.

(h) And (3) fixed value analysis and standard value determination: randomly drawing ten finished massive standard samples from each of 7 levels, processing the ten finished massive standard samples into a crumb shape to obtain crumb-shaped chemical samples with the weight of 1.5kg, and fully and uniformly mixing the crumb-shaped chemical samples for analysis and value determination; analyzing the normality, abnormal value and equal precision of the average value of the data, and determining a standard value, wherein the standard value is the total average value of each fixed value data;

in a specific embodiment of the present invention, the constant value analyzing and standard value determining in step (h) specifically comprises the following steps:

(1) collaborative fixed value unit

At least eight authoritative laboratories which are approved by laboratories or participate in the value determination of metallurgical standard samples for a plurality of times in China (or abroad) are selected to participate in the cooperative value determination, wherein the authoritative laboratories include: shanghai materials institute, Shandong province metallurgy science research institute Co., Ltd, Taiyuan iron and steel group Co., Ltd, Shandong quanson detection service Co., Ltd, and the like, each participating in the rating laboratory should be rated by using a plurality of accurate and reliable analysis methods.

(2) Analytical method

Each element is subjected to value determination by at least more than two national standard methods or accurate and reliable analysis methods.

(3) Analytical data summarization and data processing

a. Each laboratory adopts national standard or other accurate and reliable analysis methods, each element reports four groups of independent data, the range of the four independent data of each element is not more than 1.3r, and the average value of the group of data is calculated;

b. checking whether abnormal values exist among the average values of each group by using a Grubbs method;

c. checking whether each group of data has equal precision by using a Koclen criterion;

d. the normality of the average values of each group is inspected by a Charpy-Wilson method, and the normality distribution of the statistics or the approximate normal distribution of the statistics is met;

e. and (3) trimming the effective digits after the decimal point of the standard value according to GB/T8710-2008 'numerical value trimming rule and representation and judgment of limit numerical values', and aligning the uncertainty of the standard value with the digit after the decimal point of the standard value.

(4) Determination of standard values and evaluation of uncertainty

In a specific embodiment of the invention, the standard value is the total average of the individual fixed value data, and the uncertainty of the standard value comprises the uncertainty of the fixed value analysis, i.e. the standard deviation of the average and the non-uniformity of the standard sample and the stability of the standard sample. According to the regulation of GB/T15000.3-2008, the calculation formula of the uncertainty is as follows:

the extended uncertainty is:

wherein n is the number of groups of constant value data, u_charTo determine the standard uncertainty caused, u_bbStandard uncertainty, i.e. s, for testing the homogeneity of a standard sample_bb；u_ltsAnd u_stsStandard uncertainties for long term and short term stability, respectively, of the standard samples. S is the standard deviation of single measurement of fixed value statistics; the spreading factor k is 2 with a 95% confidence probability. The standard value after decimal point is the effective number: xx.xx, x.xx, 0.XXX, 0.0XX, 0.00XX, 0.000X; the uncertainty typically retains only one significant digit after the decimal point and is aligned with the last digit of the standard value, otherwise, the standard value is also scaled. Unless the standard value is high, or it is difficult to determine the standard sample material uniformly or without a quantitative analysis method with higher precision.

(i) And (3) stability test: testing the sample by adopting a spark discharge atomic emission spectrometry for 1-3 times every year;

in a specific embodiment of the present invention, the test result of step (i) is examined as follows:

if | x_CRM-x_mean| < U, whereinThe stability is good;

in the formula x_CRMIs a characteristic value of a standard sample, u_CRMAs an uncertainty on the CRM certificate; x is the number of_meanFor measured observations u_meanFor measurement uncertainty, k is the spreading factor;

in a specific embodiment of the present invention, said step (i) has a confidence probability of 95% that k is 2.

(j) And in the linear investigation, the method adopts an evaluation mode of a correlation coefficient plus a standard error to more accurately reflect the applicability of the standard sample curve.

In a specific embodiment of the invention, the step (j) sequentially excites the standard samples on the spark discharge atomic emission spectrometer, the light intensity values of each element are obtained after excitation for 3-6 times, and a linear relation is established between the average value of the light intensity values and the corresponding standard value;

in a specific embodiment of the present invention, the step (j) proves that the linearity of the set of standard samples is good when the linear correlation coefficient r is greater than 0.98;

the calculation formula of r is as follows:

wherein, C_iIs the standard content of each point and is,is the average value of the contents of each point, I_iThe light intensity or light intensity ratio of the corresponding content of each point,the average value of the light intensity or the light intensity ratio of each point.

Example 1

The embodiment provides a preparation method of a complete set of low-alloy cast iron spectrum standard sample, which comprises the following steps:

(a) designing chemical components: in a specified chemical composition range, 7 horizontal chemical compositions are designed according to the principle of equal gradient distribution, mutual interference among elements and lowest probability of generating inclusions, and are shown in a table 2;

TABLE 2 seven level chemical ingredient fixed values (w/%)

Numbering	C	Si	Mn	P	S	Cr	Ni	Mo	V	Cu	Mg
												T023-1	3.48	0.546	0.208	0.069	0.051	2.21	0.058	0.701	0.550	0.455	0.0005
T023-2	3.12	2.45	0.776	0.439	0.011	1.52	1.01	0.580	0.204	1.13	0.060
												T023-3	2.91	1.51	0.965	0.234	0.0099	0.973	0.543	0.408	0.188	0.747	0.050
T023-4	3.62	2.06	1.22	0.165	0.043	1.21	0.773	0.313	0.360	0.535	0.011
												T023-5	3.86	0.984	1.40	0.346	0.011	0.677	1.50	0.205	0.161	0.312	0.030
T023-6	2.10	3.47	1.61	0.089	0.012	0.414	2.12	0.102	0.416	0.100	0.020
												T023-7	3.40	2.35	0.604	0.016	0.0078	0.161	0.155	0.023	0.027	0.179	0.089
Numbering	Ti	B	Al	As	W	Nb	Sb	Pb	Sn	La	Ce
												T023-1	0.018	0.017	0.002	0.024	0.550	0.0033	0.045	0.071	0.038	0.001	0.004
T023-2	0.157	0.278	0.016	0.011	0.143	0.046	0.050	0.015	0.104	0.0094	0.052
												T023-3	0.055	0.113	0.010	0.022	0.040	0.030	0.082	0.015	0.086	0.0060	0.020
T023-4	0.052	0.072	0.063	0.066	0.286	0.025	0.049	0.0037	0.226	0.0018	0.0046
												T023-5	0.048	0.035	0.320	0.039	0.094	0.0016	0.086	0.032	0.102	0.0097	0.023
T023-6	0.131	0.0083	0.602	0.102	0.372	0.002	0.053	0.061	0.071	0.0060	0.015
												T023-7	0.023	0.0033	0.011	0.0025	/	/	0.0048	0.003	0.0006	0.0034	0.022

(b) Smelting: before smelting, the used raw materials are inspected, selected and cleaned of surface oxide skin and dirt; designing and preparing raw materials according to the chemical components in the step (a), smelting 200kg in each furnace by adopting a 250kg medium frequency induction furnace, smelting for 2 h-3 h at the temperature of 1400-1550 ℃, and selecting the optimal adding conditions for easily oxidized elements such as magnesium element, rare earth metal element, aluminum element, manganese element and silicon element in the smelting process: adding an aluminum element and an alloy thereof before casting, adding a magnesium element and an alloy thereof, a rare earth metal element and an alloy thereof in a casting ladle for protection, and adding a silicon element and an alloy thereof, a manganese element and an alloy thereof in the later stage of complete melting down of the rest metals;

(c) molding: casting the sample smelted in the step (b) in a mould at the temperature of 1300-1450 ℃ for 1-60 s at the speed of 1-5 t/h to complete crystallization, and obtaining a crude sample, wherein the modulus ratio of the casting is 0.4-0.6 cm; before casting, 0.1 kg-0.5 kg of metal tellurium is added into molten iron;

(d) treatment and preparation of standard samples: and (3) carrying out thermal refining on the crude sample, wherein the temperature of the thermal refining is 500-550 ℃, the heat preservation time is 2-8 h, the initial temperature of furnace cooling is the finishing temperature of the thermal refining, the time of the furnace cooling is the time when the temperature in the furnace reaches the room temperature after a furnace door is opened, and carrying out linear cutting on the processed sample to obtain a finished product block standard sample with the size of phi 35mm multiplied by 30 mm.

Effect example 1

This example provides a method for testing a standard sample obtained by the method for preparing a set of standard samples for low-alloy cast iron spectra of example 1, comprising the steps of:

(1) initial detection of a standard sample:

a. internal defect inspection:

five samples were taken from the most defective portion of each horizontal standard sample, and examined with an ultrasonic flaw detector having a resolution of 0.5 dB. No significant porosity and pores were found inside the samples. After the initial inspection is completely qualified, ultrasonic flaw detection is carried out on each sample, the qualification rate is 98%, and unqualified samples are removed.

b. White spot test:

five samples were randomly sampled from each horizontal standard sample, and the two end faces and 1/2 cross-sections of the samples were examined at 100 x magnification using an XJG-05 large metallographic microscope, as can be seen in FIG. 3, and no free graphite and no significant inclusions were found in all the samples sampled.

(2) And (3) in-unit inspection: the prepared standard samples are numbered, five samples are extracted from the parts which are easy to generate segregation in each horizontal standard sample, each sample is cut into 7 pieces by adopting a linear cutting method from bottom to top at equal intervals, and the radius 1/2 in the bottom surface direction of each piece is equal to the excitation point of the central angle of 6 points. After randomization of 7X 6 excitation points, statistics were performed by variance analysis pairwise comparison, and the specific values are listed in Table 3, where for economy, only the intra-block homogeneity test results for the third and seventh levels of the standard samples, i.e., the intra-block homogeneity test results for numbers T023-3 and T023-7, are provided. As can be seen from the data in Table 3, the value of Δ t' for each element is not greater than w, and the standard deviation is smaller than the allowable standard deviation of the method, and the maximum difference of the average values of each element between any two samples taken does not exceed the critical value. Therefore, it can be determined that the uniformity inside the cell is good.

TABLE 3 results of homogeneity test in blocks of standard samples for spectroscopic analysis of low-alloy cast irons

(3) And (3) checking the uniformity among blocks: the prepared standard samples are numbered, 10 blocks are extracted horizontally, three points are randomly excited by each block on an ARL3460 direct-reading spectrometer, and the significance of the blocks relative to the precision in the blocks is checked by adopting a single-factor variance analysis method. When the statistic F is not greater than the threshold value and the non-uniformity is not greater than 0.3 times the standard uncertainty, it is determined that the inter-blocks are uniform. As can be seen from Table 4, although Sb of T023-2 and B element F of T023-7 are more than F_αBut s_bbLess than or equal to 0.3u, also indicating that the uniformity test is qualified. In addition, since La and Ce are not given uncertainty, but the F value is not more than a critical value and T.ltoreq._wIt can also be shown that there is no significant difference between blocks. Therefore, the uniformity of all samples is judged to be qualified.

Table 4 results of uniformity test (α ═ 0.05, F_α＝1.84)

(4) And (3) fixed value analysis and standard value determination: and randomly drawing ten finished product block-shaped standard samples from each of 7 levels, processing the ten finished product block-shaped standard samples into chips to obtain chip-shaped chemical samples with the weight of 1.5kg, and fully and uniformly mixing the chip-shaped chemical samples for analysis and value determination.

(a) Collaborative fixed value unit

At least eight authoritative laboratories which are approved by laboratories or participate in the value determination of metallurgical standard samples for multiple times at home (or abroad) are selected to participate in the cooperative value determination, and each participating value determination laboratory is required to perform the value determination by adopting a plurality of accurate and reliable analysis methods.

(b) Analytical method

Each element is subjected to value determination by at least more than two national standard methods or accurate and reliable analysis methods.

(c) Analytical data summarization and data processing

(c₁) Each laboratory adopts national standard or other accurate and reliable analysis methods, each element reports four groups of independent data, the range of the four independent data of each element is not more than 1.3r, and the average value of the group of data is calculated.

(c₂) The Grubbs method was used to check whether outliers were present between the group means. No abnormal value appears among the average values of each group through detection.

(c₃) The test of each group of data by the Cocklon's criterion isWhether the precision is equal or not. Through inspection, the accuracies of Cu, Al and Pb of T023-1, Ti and La of T023-5 and Cu and La of T023-6 are different, and data are retained because the average value is equivalent to the median value.

(c₄) The normality of the average values of each group is inspected by a Charpy-Wilson method, and the normality distribution of the statistics is met.

(d) Determination of the Standard values

The standard value is the total average value of each family constant value data.

(5) And (3) stability test: testing the sample by adopting a spark discharge atomic emission spectrometry for 1-3 times every year;

the stability inspection period of the steel material is not less than three years, at least one test is carried out by adopting a spark discharge atomic emission spectrometry every year, and the test result is tested according to the following method:

if | x_CRM-x_mean| < U, whereinThe stability is good. In the formula x_CRMIs a characteristic value of a standard sample, u_CRMAs an uncertainty on the CRM certificate; x is the number of_meanFor measured observations u_meanIs the uncertainty of the measurement. At 95% confidence probability, take k 2. It should be noted that, for economy, the stability test results of the standard samples at the third level and the seventh level, namely the stability test results of the standard samples with numbers T023-3 and T023-7, are provided only, and are shown in Table 5.

TABLE 5 stability test results

As can be seen from the data in table 5, the stability of the standard sample prepared by the present invention is good, and the stability of the other five levels of standard samples is also good.

(6) Linear investigation: and sequentially exciting the standard sample on the spark discharge atomic emission spectrometer, exciting for 3-6 times to obtain the light intensity value of each element, and establishing a linear relation between the average value of the light intensity values and the corresponding standard value. When the linear correlation coefficient r is greater than 0.98, it indicates that the linearity of the set of standard samples is good.

The correlation coefficient is calculated as follows:

wherein, C_iIs the standard content of each point and is,is the average value of the contents of each point, I_iThe light intensity or light intensity ratio of the corresponding content of each point,the average value of the light intensity or the light intensity ratio of each point.

As can be seen from Table 6, the linear correlation coefficients r are all greater than 0.98, so that the curves are all ideal fits, and each point of the curve has strong correlation.

TABLE 6 table of coefficient of correlation of working curve of standard sample

Index of curve	C	Si	Mn	P	S	Cr	Ni	Mo
									r	0.995	0.999	0.999	0.999	0.998	0.999	0.999	0.999
Index of curve	V	Cu	Mg	Ti	B	Al	As	W
									r	0.999	0.999	0.998	0.999	0.999	0.999	0.999	0.999
Index of curve	Nb	Sb	Pb	Sn	La	Ce	/	/
									r	0.999	0.997	0.998	0.999	0.999	0.997	/	/

(7) User rating

The following conclusions were drawn after the use of the standard samples according to the invention by the user and after the ARL4460 test:

the standard sample set has reasonable gradient distribution of each element and more constant value items; each element has accurate and reliable fixed value; the reproducibility of each element data of the standard sample is good; the gradient correlation of each element working curve of the standard sample is ideal. Meanwhile, the requirements of production control, spectrometer evaluation, test quantity value unification and working curve production can be completely met.

(8) Compared with the foreign similar standard sample

The COMAR information base inquires domestic and foreign standard samples, related information of low-alloy cast iron series spectrum standard samples exists in the UK, and the samples are RM. Respectively as follows: NCEM No.1, NCEM No.2, NCEM No.3, NCEM No.4, NCEM No.5, LARM5/1, SIMO1/4, SIMO2/2, SIMO 2/3.

From the results of the investigation, these were developed by BAS and BCIRA in the UK. Wherein, LARM5/1 is low alloy cast iron, and the constant value elements are 12; the NCEM1-5 is a nickel-chromium cast iron series standard sample, and the number of the constant value elements is 9; three pieces of SIMO were silicon molybdenum cast iron, of which 1/4 constant elements 16, 2/2 and 2/3 constant elements seventeen. From the quantity and the fixed value level of the fixed value elements, the set of standard samples all exceed the level of the foreign similar standard samples.

From the test results, the standard sample prepared by the preparation method of the complete set of low-alloy cast iron spectrum standard sample has low inclusion content, good uniformity and more thorough whitening, so that the excitability of the sample is further improved, and the long-term stability of the material is improved. Meanwhile, by means of randomization of the excitation sequence of the in-cell inspection and uniformity inspection and the drift monitoring measures, the system deviation generated by the drift of the spectrometer along with time is eliminated, and the real deviation in blocks and among blocks is reflected more objectively; the qualification of uniformity in units and among blocks is more accurately judged by adopting variance analysis and an absolute parameter comparison method; in linear inspection, the applicability of the standard sample curve is reflected more accurately by adopting an evaluation mode of a correlation coefficient plus a standard error.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.