A coarse grain screening method, device, equipment and medium for a fighting steel bolt

Abstract

The application discloses a coarse grain screening method of a gas-fighting steel bolt, and relates to the technical field of metal inspection and detection, which comprises the following steps: preparing a gas-fighting steel bolt sample and a standard comparison sample; the gas-fighting steel bolt sample and the standard comparison sample have the same material and heat treatment system; the resistivity of the standard comparison sample is determined based on the average measurement diameter and the resistance value of the standard comparison sample; the resistivity between every two adjacent measurement points of the gas-fighting steel bolt sample is determined according to the average measurement diameter between every two adjacent measurement points and the resistance value between every two adjacent measurement points; and the resistivity between every two adjacent measurement points is compared with the resistivity of the standard comparison sample respectively, and the range of the interval of the coarse grain in the sample is determined according to the comparison result. In the screening process, the gas-fighting steel bolt is not damaged, the detection range is wide, the screening method is simple, fast and effective, and the screening efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of metal inspection and testing technology, and in particular to a method, apparatus, equipment and medium for coarse grain screening of steel bolts. Background Technology

[0002] "Zhengqi No. 1" and "Zhengqi No. 2" bolts are bainitic high-temperature bolts independently developed and manufactured in my country, collectively referred to as Zhengqi steel bolts. Zhengqi steel bolts exhibit severe microstructural inheritance and are highly sensitive to heat treatment. Improper heat treatment control can easily lead to coarse grains (coarse grains) in Zhengqi steel bolts. Coarse grains result in decreased impact toughness and are a significant cause of brittle fracture in Zhengqi steel bolts. Therefore, the standard DL / T 439-2018 "Technical Guidelines for High-Temperature Fasteners in Thermal Power Plants" stipulates that 20Cr1Mo1VNbTiB and 20Cr1Mo1VTiB steel bolts should undergo low-magnification and microscopic grain size inspection before use. The inspection method involves etching one end face of the bolt with an etchant and observing and judging the results with the naked eye, a magnifying glass, or a metallographic microscope. Coarse grains (grain size < 5 grade) are not permitted.

[0003] Currently, the metallographic method specified in the standard is the most common and traditional inspection method. The inspection results are intuitive and accurate, but it has the following problems. First, the standard reflects the overall grain size of the bolt by inspecting the end face. However, the shank bears the greatest stress in the bolt as a whole. The metallographic method's determination of whether the bolt has coarse grains is limited to the bolt end face. Practice has shown that the "Zhengqi No. 1" and "Zhengqi No. 2" bolts have uneven grain size due to the heat treatment process, and may have localized coarse grains. Therefore, only inspecting the bolt end face for coarse grains can easily lead to missed detections. Bolts that pass the end face inspection may still be at risk of breakage due to coarse grains after being put into use. Therefore, it is essential to implement overall coarse grain inspection of the bolt. Second, the metallographic method involves many steps, is time-consuming, and inefficient, making it unsuitable for large-area inspection and screening. Furthermore, the metallographic method requires grinding, polishing, and etching the bolt ends, which can cause some damage to the bolt.

[0004] Currently, some scholars have used ultrasonic non-destructive testing to inspect and screen for coarse grains in steel bolts. The principle is based on the fact that when ultrasonic waves propagate through a metallic medium and pass through grains, the waves attenuate due to scattering and absorption. The degree of attenuation is related to grain size; ultrasonic waves attenuate more in coarse grains and less in fine grains. The presence of coarse grains is determined by the degree of attenuation. Ultrasonic non-destructive testing is fast, efficient, and has a wide detection range, allowing for the inspection of the entire bolt. However, practical applications have revealed that probe sensitivity is relatively low, and ultrasonic attenuation is not significant, still leaving room for missed or false detections.

[0005] Therefore, how to perform coarse grain inspection on steel bolts without damaging them, reduce the risk of missed or incorrect detection, and improve screening efficiency is an urgent problem to be solved in this field. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method, apparatus, equipment, and medium for coarse grain screening of high-strength steel bolts, which can perform coarse grain inspection on high-strength steel bolts without damaging them, reduce the risk of missed or incorrect detection, and improve screening efficiency. The specific solution is as follows:

[0007] In a first aspect, this application discloses a method for coarse grain screening of high-strength steel bolts, including:

[0008] Prepare samples of high-strength steel bolts and standard comparative specimens; the samples of high-strength steel bolts and the standard comparative specimens have the same material and heat treatment regime;

[0009] The resistivity of the standard comparison sample is determined based on the pre-measured average measured diameter of the standard comparison sample and the resistance value of the standard comparison sample.

[0010] The resistivity between each pair of adjacent measurement points is determined based on the pre-determined average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points;

[0011] The resistivity between each two adjacent measurement points of the steel bolt sample is compared with the resistivity of the standard comparison sample, and the spacing range of coarse grains in the steel bolt sample is determined based on the comparison results.

[0012] Optionally, before determining the resistivity of the standard comparison sample based on the pre-measured average measured diameter of the standard comparison sample and the resistance value of the standard comparison sample, the method further includes:

[0013] The standard comparison sample is marked with a first preset number of measurement points, and the measurement diameter corresponding to each measurement point is determined.

[0014] The average measurement diameter of the standard comparison sample is determined based on the measurement diameter corresponding to each measurement point.

[0015] Optionally, before determining the resistivity between each pair of adjacent measurement points based on the pre-determined average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points, the method further includes:

[0016] Mark a second preset number of measurement points on the steel bolt sample, and determine the measurement diameter corresponding to each measurement point;

[0017] The average measurement diameter between each two adjacent measurement points is determined based on the measurement diameter corresponding to each measurement point.

[0018] Optionally, the process of determining the resistance value of the standard comparison sample includes:

[0019] By fixing the current terminal of the DC digital resistor to the center of the two cross sections of the standard comparison sample, and placing the potential terminal probe of the DC digital resistor at both ends of the standard comparison sample, the resistance value of the standard comparison sample is measured.

[0020] Optionally, the process of determining the resistance value between every two adjacent measurement points of the steel bolt sample includes:

[0021] By fixing the current terminal of the DC digital resistance meter to the center of the two cross sections of the steel bolt, and placing the potential terminal probe of the DC digital resistance meter on each of the measurement points, the resistance value between each two adjacent measurement points of the steel bolt sample is measured.

[0022] Optionally, determining the spacing range of coarse grains in the steel bolt sample based on the comparison results includes:

[0023] If the resistivity between two adjacent measurement points is less than that of the standard comparison sample, then the range of the distance between the two adjacent measurement points is determined as the range of coarse grain spacing.

[0024] Optionally, the coarse grain screening method for the steel bolts further includes:

[0025] The steel bolt samples were screened under preset temperature difference and preset relative humidity conditions.

[0026] Secondly, this application discloses a coarse grain screening device for high-strength steel bolts, comprising:

[0027] The preparation module is used to prepare samples of high-strength steel bolts and standard comparative specimens; the high-strength steel bolt samples and the standard comparative specimens have the same material and heat treatment regime.

[0028] The first resistivity determination module is used to determine the resistivity of the standard comparison sample based on the pre-measured average measurement diameter of the standard comparison sample and the resistance value of the standard comparison sample.

[0029] The second resistivity determination module is used to determine the resistivity between each pair of adjacent measurement points based on the pre-determined average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points.

[0030] The coarse grain screening module is used to compare the resistivity between each two adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample, and determine the spacing range of coarse grains in the steel bolt sample based on the comparison results.

[0031] Thirdly, this application discloses an electronic device, comprising:

[0032] Memory, used to store computer programs;

[0033] A processor is used to execute the computer program to implement the aforementioned disclosed method for coarse grain screening of steel bolts.

[0034] Fourthly, this application discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, it implements the aforementioned coarse grain screening method for steel bolts.

[0035] Therefore, this application proposes a method for screening coarse grains in steel bolts, comprising: preparing steel bolt samples and standard comparison samples; the steel bolt samples and the standard comparison samples having the same material and heat treatment regime; determining the resistivity of the standard comparison samples based on the pre-measured average measurement diameter and the resistance value of the standard comparison samples; determining the resistivity between each pair of adjacent measurement points based on the pre-measured average measurement diameter and the resistance value between each pair of adjacent measurement points; comparing the resistivity between each pair of adjacent measurement points of the steel bolt samples with the resistivity of the standard comparison samples, and determining the spacing range of coarse grains present in the steel bolt samples based on the comparison results. In summary, this application compares the resistivity between every two adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample to obtain the spacing range of coarse grains in the steel bolt sample. In other words, this application determines whether there are coarse grains in the steel bolt sample by comparing resistivity. In this way, the steel bolt will not be damaged during the screening process, and the screening method is simple and effective, which can promptly detect sample areas with coarse grains, improve screening efficiency, and reduce the risk of missed or false detections. Attached Figure Description

[0036] 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 only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1 This is a flowchart of a coarse grain screening method for a high-strength steel bolt disclosed in this application;

[0038] Figure 2 This application discloses a flowchart of a specific method for coarse grain screening of steel bolts.

[0039] Figure 3 This is a schematic diagram of the dimensional measurement of a standard comparative specimen disclosed in this application;

[0040] Figure 4 This is a schematic diagram of the resistance measurement of a standard comparison sample disclosed in this application;

[0041] Figure 5 This is a schematic diagram of the dimensional measurement of a prefabricated bolt sample disclosed in this application;

[0042] Figure 6 This is a schematic diagram of resistance measurement for a prefabricated bolt sample disclosed in this application;

[0043] Figure 7 This is a schematic diagram of the coarse grain screening device for a type of high-strength steel bolt disclosed in this application;

[0044] Figure 8 This is a structural diagram of an electronic device disclosed in this application. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Metallographic testing of coarse grains in steel bolts can cause damage to the bolts, and involves many steps, resulting in low efficiency. Ultrasonic non-destructive testing methods have low probe sensitivity and insignificant ultrasonic attenuation, still leaving room for missed or incorrect detections.

[0047] Therefore, this application proposes a coarse grain screening scheme for high-strength steel bolts, which can perform coarse grain inspection on high-strength steel bolts without damaging them, and reduce the risk of missed or incorrect detection.

[0048] This application discloses a method for screening coarse grains in high-strength steel bolts. See also... Figure 1 As shown, the method includes:

[0049] Step S11: Prepare a steel bolt sample and a standard comparative sample; the steel bolt sample and the standard comparative sample have the same material and heat treatment regime.

[0050] It should be noted that this embodiment requires screening the steel bolt samples under preset temperature difference and preset relative humidity conditions. In some specific embodiments, the steel bolt samples can be screened under conditions where the temperature difference is no greater than 3°C and the relative humidity is no greater than 80%.

[0051] In some embodiments, the process of preparing the steel bolt sample specifically includes: machining the steel billet of the pre-made bolt into a steel bolt sample of specified specifications by machining, with an allowable error of ±1mm. The process of preparing the standard comparison sample specifically includes: selecting the steel billet of the pre-made comparison sample, wherein the steel billet of the pre-made comparison sample is taken from the steel billet of the pre-made steel bolt sample, so as to ensure that the comparison sample and the steel bolt sample have the same material and heat treatment regime. Furthermore, the grain size of the end face of the comparison sample steel billet is inspected, specifically by metallographic method to determine the grain size level of the comparison sample steel billet, which should not be lower than level 5. Then, the comparison sample steel billet is machined into a standard comparison sample in the shape of a round bar, with a length of 100mm and a cross-sectional diameter of 10mm, with an allowable error of ±1mm.

[0052] Step S12: Determine the resistivity of the standard comparison sample based on the pre-measured average diameter of the standard comparison sample and the resistance value of the standard comparison sample.

[0053] In this embodiment, before determining the resistivity of the standard comparison sample based on the pre-measured average measurement diameter and the resistance value of the standard comparison sample, it is necessary to mark a first preset number of measurement points on the standard comparison sample, determine the measurement diameter corresponding to each measurement point, determine the average measurement diameter of the standard comparison sample based on the measurement diameter corresponding to each measurement point, and further determine the resistivity of the standard comparison sample based on the average measurement diameter and the resistance value of the standard comparison sample.

[0054] Taking the marking of 5 measurement points on the standard comparison sample as an example, firstly, the length of the standard comparison sample is measured using a vernier caliper and denoted as l. Further, 5 measurement points are marked approximately equidistantly along the sample's length. At each measurement point, the diameter is measured at right angles using a micrometer, and the average value is taken as the measured diameter at that point, denoted as d1, d2, d3, d4, and d5 respectively. The average value of the measured diameters at the 5 measurement points is taken as the average measured diameter of the standard comparison sample, denoted as d. The calculation formula is:

[0055]

[0056] Furthermore, when determining the resistance value of the standard comparison sample, a DC digital resistance meter can be used to measure the resistance value of the standard comparison sample using the four-terminal method. Specifically, by fixing the current terminal of the DC digital resistance meter at the center of the two side cross-sections of the standard comparison sample, and placing the potential terminal probe of the DC digital resistance meter at both ends of the standard comparison sample, the resistance value of the standard comparison sample is measured and recorded as R0. Then, the resistivity ρ0 of the standard comparison sample is calculated based on R0. The calculation formula is:

[0057]

[0058] Step S13: Determine the resistivity between each pair of adjacent measurement points based on the pre-determined average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points.

[0059] In this embodiment, before determining the resistivity between two adjacent measurement points based on the pre-determined average measurement diameter and resistance value between two adjacent measurement points, it is necessary to mark a second preset number of measurement points on the steel bolt sample and determine the measurement diameter corresponding to each measurement point. Then, the average measurement diameter between two adjacent measurement points is determined based on the measurement diameter corresponding to each measurement point. Further, the resistivity between two adjacent measurement points is determined based on the average measurement diameter and resistance value between two adjacent measurement points.

[0060] In some embodiments, the process of measuring the average diameter between every two adjacent measurement points includes: first, measuring the length of the steel bolt sample using vernier calipers, denoted as L; then, marking several measurement points approximately equidistantly from one end face of the sample to the other end face along the length of the steel bolt sample, denoted as point 1, point 2, point 3... point i-1, point i, point i+1... point n. Further, measuring the distance between each measurement point using vernier calipers, denoted as L1, L2, L3... L... i-1 L i L i+1 ...L n-1 Then, at each measurement point, the diameter is measured at right angles using a micrometer, and the average value is taken as the measured diameter at that point, denoted as D1, D2, D3, ... D. i-1 D i D i+1 ...D n Similarly, the average of the measured diameters at each adjacent measurement point is taken as the average measured diameter between each adjacent measurement point of the steel bolt sample, denoted as D. The calculation formula is:

[0061]

[0062] It should be noted that this embodiment utilizes a DC digital resistance meter and employs the four-terminal method to determine the resistance value between each pair of adjacent measurement points of the steel bolt sample. Specifically, by fixing the current terminal of the DC digital resistance meter to the center of the two cross-sections of the steel bolt, and placing the potential terminal probe of the DC digital resistance meter at each measurement point, the resistance value between each pair of adjacent measurement points of the steel bolt sample is measured. The measured resistance values ​​are recorded as R1, R2, R3...R... i-1 R i R i+1 …R n-1 Then, based on the resistance value between each pair of adjacent measurement points and the average measurement diameter between each pair of adjacent measurement points, the resistivity between each pair of adjacent measurement points is calculated using the following formula:

[0063]

[0064] Step S14: Compare the resistivity between each two adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample, and determine the spacing range of coarse grains in the steel bolt sample based on the comparison results.

[0065] First, it's necessary to state the following theory: According to metal physics, metals have good electrical conductivity. When an external electric field is present, the free electrons in the metal undergo directional movement, constantly colliding with positive ions that are thermal oscillators at the crystal lattice nodes. This collision hinders the electron movement, thus giving the metal a certain resistance. Resistivity is used to characterize a material's ability to resist the directional movement of charged particles in an electric field. The relationship between resistivity and resistance is as follows:

[0066]

[0067] In the formula, ρ is the resistivity, with units of μΩ·m; S is the cross-sectional area of ​​the conductor, with units of m². 2 R is the resistance value, in Ω; L is the length of the conductor, in m.

[0068] According to quantum mechanics, at various temperatures, atoms in a crystal undergo continuous thermal vibrations around their equilibrium positions. Due to the interactions between atoms, these thermal vibrations manifest as the continuous alternating aggregation and separation of atoms within the elastic range, forming lattice waves. The energy of these lattice vibrations is quantized, and the energy quanta of these lattice waves are called phonons. Quantum mechanics proves that resistivity is the statistical average effect of the interaction between electrons and phonons. According to band theory, electrons moving in a strictly periodic potential field remain in an eigenstate, and their motion is not subject to "resistance." Only when atomic vibrations, impurities, or defects cause the crystal potential field to deviate from the periodic field do electrons collide and scatter. The resistance of general metals is caused by the scattering of electrons by lattice atomic vibrations (phonons). According to quantum mechanics, the following relationships exist between conductivity and Fermi velocity, and between conductivity and resistance in metals:

[0069]

[0070]

[0071]

[0072] In the formula, ρ is the resistivity, n is the effective electron density, and m is the effective electron density. * For effective electron mass, l F For the mean free path of electrons, v F The velocity is Fermi, e is the charge of the ion, and μ = 1 / l F This is called the scattering coefficient.

[0073] According to the electronic theory of metals, the outermost electrons of each atom composing a crystal do not belong to any single atom, but are shared by all atoms. These shared electrons move in the weak periodic field of positive ions. Therefore, the near-free electron approximation or its zeroth-order approximation is often used to discuss the electronic states of metals, with the energy in k-space being E. F 0The isoenergetic surface is called the Fermi surface, which is the interface between the filled and empty states at T = 0 K. The Fermi surface of a free electron is a sphere with radius K. F As the Fermi wave vector, the ground-state Fermi energy at T=0K is:

[0074]

[0075] In the formula, h is Planck's constant, m is the electron mass, and N is the total number of electrons in the Fermi sphere.

[0076] The electron number density n is:

[0077]

[0078] The system volume can be written as V = V*(1+λ), where V is the unit cell volume at 0K. Under the condition that the total number of electrons N remains constant, if the system exhibits lattice distortion, then:

[0079]

[0080] Therefore, the relationship between the system's Fermi energy and lattice distortion can be written as:

[0081]

[0082] The free electron theory of metals compares electron gas to an ideal gas, placing free electrons at the highest energy E. F The motion is considered as the Fermi velocity V of the electron. F There is a relationship between Fermi velocity and Fermi energy:

[0083]

[0084] From the above formulas, the relationship between resistivity and Fermi energy, Fermi velocity, and lattice distortion can be derived:

[0085]

[0086] It can be seen that the resistivity generally increases with the increase of crystal distortion. The smaller the grain size, the larger the volume fraction of grain boundaries. The movement of electrons is restricted by the grain boundaries, thus exhibiting quantum effects. At this time, conduction electrons will be further scattered by the surface, which affects the mean free path of electrons and further affects the conductivity of metallic materials.

[0087] In summary, resistivity is inversely proportional to grain size. Therefore, based on the relationship between the resistivity of each two adjacent measurement points of the steel bolt sample and the resistivity of the standard comparison sample, this embodiment can deduce the relationship between the grain size of each two adjacent measurement points and the standard grain size, and further deduce the spacing range of coarse grains in the sample.

[0088] Therefore, this application proposes a method for screening coarse grains in steel bolts, comprising: preparing steel bolt samples and standard comparison samples; the steel bolt samples and the standard comparison samples having the same material and heat treatment regime; determining the resistivity of the standard comparison samples based on the pre-measured average measurement diameter and the resistance value of the standard comparison samples; determining the resistivity between each pair of adjacent measurement points based on the pre-measured average measurement diameter and the resistance value between each pair of adjacent measurement points; comparing the resistivity between each pair of adjacent measurement points of the steel bolt samples with the resistivity of the standard comparison samples, and determining the spacing range of coarse grains present in the steel bolt samples based on the comparison results. In summary, this application compares the resistivity between every two adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample to obtain the spacing range of coarse grains in the steel bolt sample. In other words, this application determines whether there are coarse grains in the steel bolt sample by comparing resistivity. In this way, the steel bolt will not be damaged during the screening process, and the screening method is simple and effective, which can promptly detect sample areas with coarse grains, improve screening efficiency, and reduce the risk of missed or false detections.

[0089] This application discloses a specific method for coarse-grain screening of steel bolts. Compared with the previous embodiment, this embodiment further explains and optimizes the technical solution. See also... Figure 2 As shown, it specifically includes:

[0090] Step S21: Prepare a steel bolt sample and a standard comparative sample; the steel bolt sample and the standard comparative sample have the same material and heat treatment regime.

[0091] Step S22: Determine the resistivity of the standard comparison sample based on the pre-measured average diameter of the standard comparison sample and the resistance value of the standard comparison sample.

[0092] Step S23: Determine the resistivity between each pair of adjacent measurement points based on the pre-determined average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points.

[0093] It should be noted that the more specific working process of steps S21, S22, and S23 can be found in the aforementioned disclosed embodiments, and will not be described in detail here.

[0094] Step S24: Compare the resistivity between each pair of adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample. If the resistivity between two adjacent measurement points is less than the resistivity of the standard comparison sample, then the distance between the two adjacent measurement points is determined as the range of coarse grain spacing.

[0095] In this embodiment, after comparing the resistivity between every two adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample, if there exists a resistivity ρ between two adjacent measurement points... i If the resistivity ρ0 of the steel bolt sample is less than that of the standard comparison sample, then the grain size within the range from point i to point i+1 of the steel bolt sample is considered to be higher than that of the standard comparison sample. Further, it can be deduced that the grain size within the range from point i to point i+1 of the steel bolt sample is lower than that of the standard comparison sample. Furthermore, to make the test results more accurate, a more detailed inspection and confirmation of the range from point i to point i+1 of the steel bolt sample can be performed using metallographic methods. If there is a resistivity ρ0 between two adjacent measurement points... i If the resistivity ρ0 of the standard comparison sample is greater than or equal to that of the standard comparison sample, it can be considered that the grain size of the bolt prefabricated sample within the distance from point i to point i+1 is lower than that of the standard comparison sample. Furthermore, it can be deduced that the grain size within the distance from point i to point i+1 is higher than that of the standard comparison sample, indicating that there are no coarse grains within the distance from point i to point i+1.

[0096] The following example illustrates the implementation method by performing a coarse-grain screening inspection on a "Striving No. 1" bolt to be screened. The specific operating steps are as follows:

[0097] Step 1: Selection of steel billet for comparison test. The steel billet for the prefabricated comparison test is taken from the steel billet of the prefabricated new bolt.

[0098] Step 2: Perform grain size inspection on the end face of the comparative sample steel billet; determine the grain size level of the comparative sample steel billet to be grade 5 by metallographic method.

[0099] Step 3: Preparation of standard comparison sample 1; The steel billet of the comparison sample is machined into a round bar shape. The length of standard comparison sample 1 is 100mm and the cross-sectional diameter is 10mm, with an allowable error of ±1mm.

[0100] Step 4: Refer to Figure 3The dimensions of standard comparison sample 1 were measured. The length of standard comparison sample 1 was measured with vernier calipers, and the length l = 100.02 mm. Five measurement points (1-1 to 1-5) were marked at approximately equal intervals along the length of the sample. The diameter of each measurement point was measured at right angles with a micrometer, and the average value was taken as the measured diameter at that point, and recorded as d1, d2, d3, d4 and d5 respectively. The measured values ​​were d1 = 10.01 mm, d2 = 10.02 mm, d3 = 10.02 mm, d4 = 9.98 mm, and d5 = 9.98 mm. The average value of the measured diameters at the five measurement points was taken as the average diameter d of the standard comparison sample, and the calculated value was d = 10.00 mm.

[0101] Step 5: Refer to Figure 4 The resistance value of the standard comparison sample 1 was determined using a DC digital resistance meter 3 and the four-terminal method. The arrangement of the four-terminal method for resistance measurement is as follows: the high-end constant current interface 3-1 of the DC digital resistance meter 3 is connected to the high-end constant current lead 3-6; the high-end constant current connector 3-8 of the high-end constant current lead 3-6 is fixed at the center of one side of the cross-section of the standard comparison sample 1; the low-end constant current interface 3-2 of the DC digital resistance meter 3 is connected to the low-end constant current lead 3-7; the low-end constant current connector 3-9 of the low-end constant current lead 3-7 is fixed at the center of the other side of the cross-section of the standard comparison sample 1; the high-end potential interface of the DC digital resistance meter 3... Connect port 3-3 to the high-side potential lead 3-10. Place the high-side potential probe 3-12 of the high-side potential lead 3-10 at one end of the standard comparison sample 1. Connect the low-side potential interface 3-4 of the DC digital resistor 3 to the low-side potential lead 3-11. Place the low-side potential probe 3-13 of the low-side potential lead 3-11 at the other end of the standard comparison sample 1. Ensure that the high-side constant current connector 3-8 and the high-side potential probe 3-12 are on the same side, and that the low-side constant current connector 3-9 and the low-side potential probe 3-13 are on the same side. The measured resistance value of the standard comparison sample 1 is R0 = 129.59 × 10⁻⁶. -6 Ω.

[0102] Step 6: Based on the measured resistance value and dimensions of the standard comparison sample 1, calculate the resistivity ρ0 of the standard comparison sample 1. The calculated ρ0 = 10.17 × 10⁻⁶. -2 μΩ·m.

[0103] Step 7: Preparation of bolt prefabricated sample 2; The steel billet of the prefabricated bolt is machined to the specified specifications by machining, with a length of 800mm and a cross-sectional diameter of 60mm, with an allowable error of ±1mm.

[0104] Step 8: Along the length of the sample, mark several measurement points at approximately equal intervals, starting from one end face of the bolt prefabricated sample 2 and ending at the other end face. The marked measurement points of the bolt prefabricated sample (2-1 to 2-9) are respectively recorded as point 1, point 2, point 3... point 9.

[0105] Step 9: Refer to Figure 5 The dimensions of the precast bolt sample 2 were measured. In this embodiment, a section of the precast bolt sample 2 was selected as the test object for illustration. The distance between the 4th measurement point 2-4 and the 5th measurement point 2-5 was measured with a vernier caliper and recorded as L4. The measured value of L4 was 100.04 mm. The diameters of the precast bolt sample 2-4 and the 5th measurement point 2-5 were measured at right angles with a micrometer and the average value was taken as the measured diameter at each measurement point, recorded as D4 and D5 respectively. The measured values ​​of D4 and D5 were 60.03 and 60.05 respectively. Similarly, the average value of the measured diameters at the two measurement points was taken as the average diameter D between the 4th measurement point 2-4 and the 5th measurement point 2-5 of the precast bolt sample 2. The calculated value of D was 60.04 mm.

[0106] Step 10: Reference Photo Figure 6 The resistance between the fourth measuring point 2-4 and the fifth measuring point 2-5 of the bolt precast sample 2 was determined using a DC digital resistance meter 3 via the four-terminal method. The arrangement of the four-terminal method for resistance measurement is as follows: the high-end constant current interface 3-1 of the DC digital resistance meter 3 is connected to the high-end constant current lead 3-6; the high-end constant current connector 3-8 of the high-end constant current lead 3-6 is fixed at the center of one side of the cross-section of the bolt precast sample 2; the low-end constant current interface 3-2 of the DC digital resistance meter 3 is connected to the low-end constant current lead 3-7; the low-end constant current connector 3-9 of the low-end constant current lead 3-7 is fixed at the center of the other side of the cross-section of the bolt precast sample 2; and the high-end potential interface 3-3 of the DC digital resistance meter 3 is connected to... The high-end potential lead 3-10 and its high-end potential probe 3-12 are placed at the 5th measurement point 2-5 of the bolt prefabricated sample 2. The low-end potential interface 3-4 of the DC digital resistance meter 3 is connected to the low-end potential lead 3-11, and the low-end potential probe 3-13 of the low-end potential lead 3-11 is placed at the 4th measurement point 2-4 of the bolt prefabricated sample 2. The high-end constant current connector 3-8 and the high-end potential probe 3-12 are kept on the same side, and the low-end constant current connector 3-9 and the low-end potential probe 3-13 are kept on the same side. The measured resistance value R4 between the 4th measurement point 2-4 and the 5th measurement point 2-5 of the bolt prefabricated sample 2 is 4.389 × 10⁻⁶. -6 Ω.

[0107] Step 11: Based on the measured resistance value and dimensions between the 4th measurement point 2-4 and the 5th measurement point 2-5 of the precast bolt sample 2, calculate the resistivity ρ4 between these two points. The calculated ρ4 = 12.42 × 10⁻⁶. -2 μΩ·m:

[0108] Step 12: Compare the resistivity ρ4 between the 4th measurement point 2-4 and the 5th measurement point 2-5 of the bolt prefabricated sample 2 with the resistivity ρ0 of the standard comparison sample 1. It can be seen that if ρ4 > ρ0, then the grain size within the distance between the 4th measurement point 2-4 and the 5th measurement point 2-5 of the bolt prefabricated sample (2) is considered to be higher than the grain size of the standard comparison sample 1, that is, there is no coarse grain. Repeat steps 9 to 12 above to calculate the resistivity between each adjacent measurement point and compare it with the resistivity ρ0 of the standard comparison sample 1. In this way, the coarse grain screening inspection of the "Zhengqi No. 1" bolt to be screened is completed.

[0109] In summary, this application utilizes a DC digital resistance meter and a four-terminal method to measure the resistance of a standard comparison sample and a pre-fabricated bolt sample. The resistivity is then calculated using a formula, and by comparing the resistivity, the presence or absence of coarse grains in the bolt can be determined. Compared to traditional metallographic methods, this application does not damage the bolt, has a wide detection range, and can inspect the entire bolt. Furthermore, this application is simple and fast, improving screening efficiency and enabling timely detection of coarse grains in the bolt sample, avoiding waste in subsequent processing. Moreover, the resistance measurement method used in this application is based on the study of the conductivity theory of metallic materials using quantum mechanics, achieving a cross-disciplinary and interdisciplinary integration.

[0110] Accordingly, this application also discloses a coarse-grain screening device for high-strength steel bolts, see [link to relevant documentation]. Figure 7 As shown, the device includes:

[0111] Preparation module 11 is used to prepare steel bolt samples and standard comparison specimens; the steel bolt samples and the standard comparison specimens have the same material and heat treatment regime.

[0112] The first resistivity determination module 12 is used to determine the resistivity of the standard comparison sample based on the pre-measured average measurement diameter of the standard comparison sample and the resistance value of the standard comparison sample.

[0113] The second resistivity determination module 13 is used to determine the resistivity between each pair of adjacent measurement points based on the pre-determined average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points.

[0114] The coarse grain screening module 14 is used to compare the resistivity between each two adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample, and determine the spacing range of coarse grains in the steel bolt sample based on the comparison results.

[0115] For more detailed information on the working process of each of the above modules, please refer to the relevant content disclosed in the foregoing embodiments, which will not be repeated here.

[0116] Therefore, this application proposes a method for screening coarse grains in steel bolts, comprising: preparing steel bolt samples and standard comparison samples; the steel bolt samples and the standard comparison samples having the same material and heat treatment regime; determining the resistivity of the standard comparison samples based on the pre-measured average measurement diameter and the resistance value of the standard comparison samples; determining the resistivity between each pair of adjacent measurement points based on the pre-measured average measurement diameter and the resistance value between each pair of adjacent measurement points; comparing the resistivity between each pair of adjacent measurement points of the steel bolt samples with the resistivity of the standard comparison samples, and determining the spacing range of coarse grains present in the steel bolt samples based on the comparison results. In summary, this application compares the resistivity between every two adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample to obtain the spacing range of coarse grains in the steel bolt sample. In other words, this application determines whether there are coarse grains in the steel bolt sample by comparing resistivity. In this way, the steel bolt will not be damaged during the screening process, and the screening method is simple and effective, which can promptly detect sample areas with coarse grains, improve screening efficiency, and reduce the risk of missed or false detections.

[0117] Furthermore, embodiments of this application also provide an electronic device. Figure 8 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content of the diagram should not be construed as limiting the scope of this application.

[0118] Figure 8 This is a schematic diagram of the structure of an electronic device 20 provided in an embodiment of this application. Specifically, the electronic device 20 may include: at least one processor 21, at least one memory 22, a display screen 23, an input / output interface 24, a communication interface 25, a power supply 26, and a communication bus 27. The memory 22 stores a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the coarse grain screening method for steel bolts disclosed in any of the foregoing embodiments. Alternatively, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0119] In this embodiment, the power supply 26 is used to provide operating voltage for each hardware device on the electronic device 20; the communication interface 25 can create a data transmission channel between the electronic device 20 and external devices, and the communication protocol it follows can be any communication protocol applicable to the technical solution of this application, and is not specifically limited here; the input / output interface 24 is used to acquire external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs, and is not specifically limited here.

[0120] Furthermore, the memory 22, as a carrier for resource storage, can be a read-only memory, random access memory, disk, or optical disk, etc. The resources stored thereon may include computer programs 221, and the storage method may be temporary storage or permanent storage. In addition to including a computer program capable of performing the coarse grain screening method for steel bolts executed by the electronic device 20 as disclosed in any of the foregoing embodiments, the computer program 221 may further include computer programs capable of performing other specific tasks.

[0121] Furthermore, embodiments of this application also disclose a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, it implements the aforementioned coarse grain screening method for steel bolts.

[0122] For the specific steps of this method, please refer to the relevant content disclosed in the foregoing embodiments, which will not be repeated here.

[0123] The various embodiments in this application are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. For the same or similar parts between the various embodiments, refer to each other. As for the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and relevant parts can be referred to in the method section.

[0124] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0125] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0126] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0127] The above provides a detailed description of the coarse grain screening method, apparatus, equipment, and medium for high-strength steel bolts provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for screening coarse grains in high-strength steel bolts, characterized in that, include: Prepare samples of high-strength steel bolts and standard comparative specimens; the samples of high-strength steel bolts and the standard comparative specimens have the same material and heat treatment regime; The resistivity of the standard comparison sample is determined based on the pre-measured average diameter of the standard comparison sample and the resistance value of the standard comparison sample. The resistivity between each pair of adjacent measurement points is determined based on the average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points; the measurement points are measurement points marked in advance on a standard comparison sample; The resistivity between each two adjacent measurement points of the steel bolt sample is compared with the resistivity of the standard comparison sample, and the spacing range of coarse grains in the steel bolt sample is determined based on the comparison results. Before determining the resistivity of the standard comparison sample based on the pre-measured average measured diameter of the standard comparison sample and the resistance value of the standard comparison sample, the method further includes: The standard comparison sample is marked with a first preset number of measurement points, and the measurement diameter corresponding to each measurement point is determined. The average measurement diameter of the standard comparison sample is determined based on the measurement diameter corresponding to each measurement point. Before determining the resistivity between each pair of adjacent measurement points based on the pre-determined average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points, the method further includes: Mark a second preset number of measurement points on the steel bolt sample, and determine the measurement diameter corresponding to each measurement point; The average measurement diameter between each two adjacent measurement points is determined based on the measurement diameter corresponding to each measurement point. The process of determining the resistance value of the standard comparison sample includes: By fixing the current terminal of the DC digital resistor to the center of the two cross sections of the standard comparison sample, and placing the potential terminal probe of the DC digital resistor at both ends of the standard comparison sample, the resistance value of the standard comparison sample is measured. The process of determining the resistance value between each two adjacent measurement points of the steel bolt sample includes: By fixing the current terminal of the DC digital resistance meter to the center of the two cross sections of the steel bolt, and placing the potential terminal probe of the DC digital resistance meter on each of the measurement points, the resistance value between each two adjacent measurement points of the steel bolt sample is measured.

2. The method for coarse-grain screening of steel bolts according to claim 1, characterized in that, The determination of the spacing range of coarse grains in the steel bolt sample based on the comparison results includes: If the resistivity between two adjacent measurement points is less than that of the standard comparison sample, then the range of the distance between the two adjacent measurement points is determined as the range of coarse grain spacing.

3. The method for coarse-grain screening of steel bolts according to any one of claims 1 to 2, characterized in that, Also includes: The steel bolt samples were screened under preset temperature difference and preset relative humidity conditions.

4. A coarse-grain screening device for high-strength steel bolts, characterized in that, include: The preparation module is used to prepare samples of high-strength steel bolts and standard comparative specimens; the high-strength steel bolt samples and the standard comparative specimens have the same material and heat treatment regime. The first resistivity determination module is used to determine the resistivity of the standard comparison sample based on the pre-measured average measurement diameter of the standard comparison sample and the resistance value of the standard comparison sample. The second resistivity determination module is used to determine the resistivity between each pair of adjacent measurement points based on the average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points, wherein the measurement points are measurement points marked in advance on a standard comparison sample; The coarse grain screening module is used to compare the resistivity between each two adjacent measurement points of the steel bolt sample with the resistivity of the standard comparison sample, and determine the spacing range of coarse grains in the steel bolt sample based on the comparison results. The coarse grain screening device for high-quality steel bolts is also used for: Before determining the resistivity of the standard comparison sample based on the pre-determined average measurement diameter and the resistance value of the standard comparison sample, a first preset number of measurement points are marked on the standard comparison sample, and the measurement diameter corresponding to each measurement point is determined. The average measurement diameter of the standard comparison sample is determined based on the measurement diameter corresponding to each measurement point. Before determining the resistivity between each pair of adjacent measurement points based on the pre-determined average measurement diameter between each pair of adjacent measurement points and the resistance value between each pair of adjacent measurement points, the steel bolt sample is marked with a second preset number of measurement points, and the measurement diameter corresponding to each measurement point is determined. The average measurement diameter between each two adjacent measurement points is determined based on the measurement diameter corresponding to each measurement point. The process of determining the resistance value of the standard comparison sample includes: By fixing the current terminal of the DC digital resistor to the center of the two cross sections of the standard comparison sample, and placing the potential terminal probe of the DC digital resistor at both ends of the standard comparison sample, the resistance value of the standard comparison sample is measured. The process of determining the resistance value between each two adjacent measurement points of the steel bolt sample includes: By fixing the current terminal of the DC digital resistance meter to the center of the two cross sections of the steel bolt, and placing the potential terminal probe of the DC digital resistance meter on each of the measurement points, the resistance value between each two adjacent measurement points of the steel bolt sample is measured.

5. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the coarse grain screening method for steel bolts as described in any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that, Used to store a computer program; wherein, when the computer program is executed by a processor, it implements the coarse grain screening method for steel bolts as described in any one of claims 1 to 3.

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