Compensation method for conductivity testing of alloy plates under low temperature conditions

Abstract

This invention relates to a method for compensating for the conductivity of alloy sheets under low-temperature conditions, belonging to the field of measurement. The purpose of this invention is to address the problem of poor accuracy in measuring the conductivity of alloy materials under low-temperature conditions using existing methods. The method involves first selecting an alloy sheet with good uniformity and minimal fluctuation from multiple sheets of the same material using a variance calculation method. Then, a small piece is cut from this alloy sheet as a base material and sent to the laboratory. The conductivity of the sheet is accurately measured at an ambient temperature of 20°C, serving as a calibration value. The average conductivity of the base material is then measured under various low-temperature conditions. Using the calibration value, the average conductivity of the base material under various low-temperature conditions, and a formula, an average low-temperature compensation coefficient is obtained. This average temperature compensation coefficient is assigned to the conductivity measuring instrument, and combined with the instrument's temperature compensation function, conductivity compensation is achieved. This method is used for conductivity compensation under low-temperature conditions.

Description

Technical Field

[0001] This invention relates to conductivity measurement and belongs to the field of measurement. Background Technology

[0002] With the development of defense and aerospace products, higher requirements have been placed on the comprehensive performance of aluminum alloys. The strength, hardness, and plasticity indicators traditionally used to test the performance of aluminum alloys are no longer sufficient to fully reflect their comprehensive properties. The electrical properties of metallic materials, as one of the indicators reflecting their comprehensive performance, are receiving increasing attention. In particular, electrical conductivity, as one of the electrical property indicators of metallic materials, not only reflects the material's ability to conduct electricity but is also related to the material's composition and internal structure, which in turn is related to its heat treatment state. Therefore, the electrical conductivity of a material is necessarily related to its heat treatment state and mechanical properties (because the mechanical properties of a material are also determined by its composition and internal structure). In recent years, most processing enterprises both domestically and internationally have adopted the method of measuring electrical conductivity to determine the heat treatment process and certain mechanical properties of alloys.

[0003] In domestic and international conductivity testing standards, the conductivity values ​​are all based on the conductivity of the material at 20℃. The conductivity of metals often fluctuates significantly with changes in ambient temperature. When the ambient temperature decreases, the measured conductivity values ​​are generally higher. However, the low temperatures in factory environments can lead to significant differences from 20℃, making it difficult to meet the standard requirements for ambient temperature testing and resulting in inaccurate conductivity measurements. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of poor accuracy in measuring the electrical conductivity of alloy materials under low-temperature conditions, and to propose a method for compensating for the electrical conductivity testing of alloy plates under low-temperature conditions.

[0005] A method for compensating for the conductivity testing of alloy plates under low-temperature conditions, the method comprising the following:

[0006] Step 1: Take multiple alloy plates of the same material and set multiple sampling ambient temperatures. Each sampling ambient temperature value is within the range of 0℃ to 20℃. Each alloy plate goes through each sampling ambient temperature. At each sampling ambient temperature, use a conductivity measuring instrument to measure the conductivity at multiple locations on each alloy plate and take the average value to obtain the average conductivity of each alloy at each sampling ambient temperature. The temperature of each sampling ambient temperature is different.

[0007] Step 2: Based on the average conductivity of each alloy at each sampling ambient temperature and the conductivity at each location on each alloy plate, obtain the conductivity variance of each alloy plate.

[0008] Step 3: Select the alloy plate with the smallest conductivity variance from the multiple alloy plates obtained in Step 2, cut a piece from the alloy plate as the base material, obtain the conductivity of the base material at an ambient temperature of 20℃ as the calibration value, and obtain the average conductivity of the base material at each sampling ambient temperature.

[0009] Step 4: Substitute the average conductivity of the base material at each sampling ambient temperature, the temperature compensation coefficient of the base material provided by the conductivity measuring instrument, and the sampling ambient temperature value into the average conductivity formula. Substitute the calibration value and the sampling ambient temperature value into the calibration value formula at 20℃. Combine the average conductivity formula at the same sampling ambient temperature value with the calibration value formula at 20℃ to obtain the actual temperature compensation coefficient at each sampling ambient temperature.

[0010] Step 5: Take the average value of the actual temperature compensation coefficients under multiple sampling ambient temperatures to obtain the average temperature compensation coefficient;

[0011] Step 6: Assign the average temperature compensation coefficient to the conductivity measuring instrument to achieve conductivity compensation.

[0012] Preferably, there are three sampling ambient temperatures: 5℃, 10℃, and 15℃.

[0013] Preferably, the formula for the average conductivity is:

[0014]

[0015] In the formula, T 20 At 20℃, T 环境温度 For the sampled ambient temperature value, α 仪器 This refers to the temperature compensation coefficient of the base material in the conductivity measuring instrument. The conductivity value is the value at the sampling ambient temperature.

[0016] Preferably, in step 4, the calibration value formula for 20℃ is:

[0017]

[0018] In the formula, α 实际 This is the actual temperature compensation coefficient.

[0019] Preferably, in step 6, the formula for compensating for conductivity is:

[0020] σ T =σ 20 (1+α·dT);

[0021] In the formula, α is the average temperature compensation coefficient, and σ 20 This is the calibration value, where dT is the temperature difference between the actual temperature and 20℃, and σ is the calibrated value.T This represents the electrical conductivity value of the alloy sheet at temperature T.

[0022] Preferably, in step 1, the conductivity at multiple points on each alloy plate is measured using a conductivity measuring instrument, specifically as follows:

[0023] Ten points were selected on each alloy sheet: one point at each of the four corners, one point in the middle, and five points at the other locations excluding the corners and the middle.

[0024] The conductivity of each alloy plate was measured at five points: the four corners and the middle.

[0025] Preferably, in step 1, the alloy sheet is an aluminum alloy.

[0026] Preferably, the conductivity measuring instrument is a Horst 2.069 eddy current conductivity meter.

[0027] The beneficial effects of this invention are:

[0028] This application utilizes a variance calculation method to first select an alloy sheet with good uniformity and small fluctuations from multiple alloy sheets of the same material. Good uniformity means that the electrical conductivity is uniform at all locations on the alloy sheet. Then, a small piece is cut from this alloy sheet as the base material and sent to the laboratory. In the laboratory, the electrical conductivity of the wood board at an ambient temperature of 20°C is accurately measured as a calibration value. Then, the average electrical conductivity of the base material is measured under various low-temperature environments. Using the calibration value, the average electrical conductivity of the base material under various low-temperature environments, and a formula, a compensation coefficient for the average low-temperature environment is obtained. After inputting this coefficient into a conductivity measuring instrument, the same conductivity measuring instrument is used again to measure a board of the same material as the base material. The displayed conductivity value is accurate and equivalent to the conductivity measured at an ambient temperature of 20°C, thus being more accurate.

[0029] Therefore, in order to improve the accuracy of conductivity testing at lower ambient temperatures (sampling ambient temperature) and address the difference in conductivity values ​​between low-temperature environments (5-15℃) and 20℃, this application establishes a testing compensation method for different sampling ambient temperatures. Specifically, it adopts a method of determining the temperature compensation coefficient so that the compensated instrument can be applied to low-temperature production site testing, achieving accurate measurement and non-destructive testing. Attached Figure Description

[0030] Figure 1 A flowchart of a method for compensating for conductivity testing of alloy plates under low-temperature conditions;

[0031] Figure 2 The location point is taken from the alloy sheet. Detailed Implementation

[0032] 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.

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0035] Specific implementation method one: Combining Figure 1 and Figure 2 This embodiment describes a method for compensating for the conductivity of alloy plates under low-temperature conditions. The method includes the following:

[0036] Step 1: Take multiple alloy plates of the same material and set multiple sampling ambient temperatures. Each sampling ambient temperature value is within the range of 0℃ to 20℃. Each alloy plate goes through each sampling ambient temperature. At each sampling ambient temperature, use a conductivity measuring instrument to measure the conductivity at multiple locations on each alloy plate and take the average value to obtain the average conductivity of each alloy at each sampling ambient temperature. The temperature of each sampling ambient temperature is different.

[0037] Step 2: Based on the average conductivity of each alloy at each sampling ambient temperature and the conductivity at each location on each alloy plate, obtain the conductivity variance of each alloy plate.

[0038] Step 3: Select the alloy plate with the smallest conductivity variance from the multiple alloy plates obtained in Step 2, cut a piece from the alloy plate as the base material, obtain the conductivity of the base material at an ambient temperature of 20℃ as the calibration value, and obtain the average conductivity of the base material at each sampling ambient temperature.

[0039] Step 4: Substitute the average conductivity of the base material at each sampling ambient temperature, the temperature compensation coefficient of the base material provided by the conductivity measuring instrument, and the sampling ambient temperature value into the average conductivity formula. Substitute the calibration value and the sampling ambient temperature value into the calibration value formula at 20℃. Combine the average conductivity formula at the same sampling ambient temperature value with the calibration value formula at 20℃ to obtain the actual temperature compensation coefficient at each sampling ambient temperature.

[0040] Step 5: Take the average value of the actual temperature compensation coefficients under multiple sampling ambient temperatures to obtain the average temperature compensation coefficient;

[0041] Step 6: Assign the average temperature compensation coefficient to the conductivity measuring instrument to achieve conductivity compensation.

[0042] In this embodiment, when applied, step 6 specifically involves: inputting the average temperature compensation coefficient into the conductivity-temperature relationship formula inside the conductivity measuring instrument; when using the conductivity measuring instrument to measure an alloy plate of the same material as the base material, the probe of the conductivity measuring instrument inputs the sensed surface temperature of the alloy plate into the conductivity-temperature relationship formula, and the conductivity-temperature relationship formula outputs the current conductivity value of the alloy plate, which is displayed on the conductivity measuring instrument, thereby achieving conductivity compensation.

[0043] The alloy sheet with the smallest conductivity variance is the sheet with uniform conductivity. The conductivity of this sheet is used to calibrate the sheet at low temperatures, making the conductivity of the sheet measured at low temperatures more accurate.

[0044] In step 2, the variance of the conductivity of each alloy plate is calculated as follows:

[0045] For example, three sampling ambient temperatures were used: 5℃, 10℃, and 15℃. One alloy with uniform conductivity was selected from the three alloy samples. The conductivity of this first alloy was measured at two points on the sample at 5℃. The conductivity at these two points was represented by n. 11 and m 11 This indicates that the conductivity values ​​at two locations on the first alloy piece were measured at 10℃, and the conductivity at the two points is represented by n. 12 and m 12 This indicates that the conductivity values ​​at two locations on the first alloy piece were measured at 15°C, and the conductivity at the two points is represented by n. 13 and m 13 The conductivity values ​​at two locations on the second and third alloys are named as those on the first alloy; the average conductivity of the first alloy at 5°C is... The average value is represented by f;

[0046] The average conductivity of each alloy at each sampling ambient temperature, and the conductivity at multiple locations on each alloy plate are shown in the table below:

[0047] Table 1:

[0048]

[0049]

[0050]

[0051]

[0052] The fabrication of the base material in this application strictly complies with the requirements for conductivity standard specifications in GB / T 12966-2008, ASTM E1004-2017, and MIL-STD-1537C. The base material dimensions should be no less than 25mm × 25mm, the thickness no less than 5mm, and the surface roughness parameter (Ra) no greater than 3.2μm.

[0053] Specific Implementation Method Two: This implementation method further defines the conductivity testing and compensation method for alloy plates under low-temperature conditions described in Specific Implementation Method One. In this implementation method, there are three sampling environment temperatures: 5℃, 10℃, and 15℃.

[0054] In this embodiment, a temperature value is selected every 5°C, so three temperature values ​​are chosen. The reason for selecting a temperature value every 5°C is that the difference in conductivity within 5°C is not significant, so three temperature values ​​are sufficient. It would be better if more low-temperature values ​​could be measured.

[0055] Specific Implementation Method Three: This implementation method further defines the conductivity testing and compensation method for alloy plates under low-temperature conditions described in Specific Implementation Method One. In this implementation method, the formula for the average conductivity value in step 4 is:

[0056]

[0057] In the formula, T 20 At 20℃, T 环境温度 For the sampled ambient temperature value, α 仪器 This refers to the temperature compensation coefficient of the base material in the conductivity measuring instrument. The conductivity value is the value at the sampling ambient temperature.

[0058] In this embodiment, α 仪器 The value can be found by referring to the temperature compensation coefficient table for different materials on the conductivity measuring instrument, which is to say, the temperature compensation coefficient of the base material.

[0059] Specific Implementation Method Four: This implementation method further defines the conductivity testing and compensation method for alloy plates under low-temperature conditions described in Specific Implementation Method Three. In this implementation method, the calibration value formula for 20℃ in step 4 is as follows:

[0060]

[0061] In the formula, α 实际 This is the actual temperature compensation coefficient.

[0062] In this embodiment, taking three sampling ambient temperatures of 5℃, 10℃ and 15℃ as examples, the average temperature compensation coefficient of the alloy is calculated by combining the formula for the average conductivity and the formula for the conductivity calibration value at 20℃.

[0063] Table 2 Temperature compensation coefficients of 2124-TB51 alloy at 5-15℃

[0064]

[0065] Specific Implementation Method Five: This implementation method further defines the conductivity testing and compensation method for alloy plates under low-temperature conditions described in Specific Implementation Method Four. In this implementation method, the conductivity compensation formula in step 6 is as follows:

[0066] σ T =σ 20 (1+α·dT);

[0067] In the formula, α is the average temperature compensation coefficient, and σ 20 This is the calibration value, where dT is the temperature difference between the actual temperature and 20℃, and σ is the calibrated value. T This represents the electrical conductivity value of the alloy sheet at temperature T.

[0068] In this embodiment, σ T This is the electrical conductivity value of the current alloy plate output in step 6.

[0069] Specific Implementation Method Six: This implementation method further defines the conductivity testing and compensation method for alloy plates under low-temperature conditions described in Specific Implementation Method One. In this implementation method, in step 1, the conductivity at multiple locations on each alloy plate is measured using a conductivity measuring instrument, specifically as follows:

[0070] Ten points were selected on each alloy sheet: one point at each of the four corners, one point in the middle, and five points at the other locations excluding the corners and the middle.

[0071] The conductivity of each alloy plate was measured at five points: the four corners and the middle.

[0072] In this embodiment, the conductivity measuring instrument can also measure the conductivity at more than 5 locations on each alloy plate, such as the four corners, the middle position, and one other position besides the four corners and the middle position, for a total of 6 locations.

[0073] The more location points you take, the more accurate your calculations will be.

[0074] Figure 2 The conductivity measurement point in the text refers to the location point.

[0075] Specific Implementation Method Seven: This implementation method further defines the conductivity testing and compensation method for alloy plates under low-temperature conditions described in Specific Implementation Method One. In this implementation method, the alloy plate in step 1 is an aluminum alloy.

[0076] Specific Implementation Method Eight: This implementation method further defines the conductivity testing and compensation method for alloy plates under low-temperature conditions described in Specific Implementation Method One. In this implementation method, the conductivity measuring instrument used is a Horst 2.069 eddy current conductivity meter.

[0077] In this embodiment, the conductivity measuring instrument selected in this application is a Horst 2.069 eddy current conductivity meter, which has good stability, sensitivity, and lift-off effect; probe: 8mm / 14mm; when using the conductivity measuring instrument to measure aluminum alloys at low temperature, the aluminum alloy base material is selected for calibration; when using the conductivity measuring instrument to measure nickel-based alloys at low temperature, the nickel-based alloy base material is selected for calibration.

[0078] The following requirements should be followed when conducting on-site testing for this application:

[0079] (1) Turn on the conductivity measuring instrument and preheat and adjust it according to the conductivity meter instruction manual. The preheating time is generally 20 minutes.

[0080] (2) Ensure the stability of the instrument readings, and then perform all necessary settings and adjustments to the equipment. Next, calibrate the conductivity meter using low, medium, and high value standard blocks. During calibration, place the probe stably in the center of the standard block. After instrument calibration, measure the medium value standard block. The deviation of the average of the three measurements from the calibrated value should not exceed ±0.2 MS / m. If the deviation is greater than this value, the instrument should be recalibrated. After calibration, place the probe on the test piece and read the measurement results on the display screen.

[0081] (3) The conductivity meter should be recalibrated every 15 minutes before testing, during continuous use, and after testing. If the deviation of the calibration value exceeds 0.2 MS / m, it should be recalibrated, and all test specimens tested after the last calibration should be retested.

[0082] (4) Measurements should be taken at representative locations such as the center and near the corners of the board. At least 5 to 10 test locations should be selected for measurement, and the conductivity values ​​at the test points should be read (the probe should be placed at a certain distance from the edge of the board to avoid edge effects).

[0083] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A method for compensating for the conductivity testing of alloy plates under low-temperature conditions, characterized in that, The method includes the following: Step 1: Take multiple alloy plates of the same material and set multiple sampling ambient temperatures. Each sampling ambient temperature value is within the range of 0℃ to 20℃. For each alloy plate, go through each sampling ambient temperature. At each sampling ambient temperature, use a conductivity measuring instrument to measure the conductivity at multiple locations on each alloy plate and take the average value to obtain the average conductivity of each alloy plate at each sampling ambient temperature. The temperature of each sampling ambient temperature is different. Step 2: Based on the average conductivity of each alloy at each sampling ambient temperature and the conductivity at each location on each alloy plate, obtain the conductivity variance of each alloy plate. Step 3: Select the alloy plate with the smallest conductivity variance from the multiple alloy plates obtained in Step 2, cut a piece from the alloy plate as the base material, obtain the conductivity of the base material at an ambient temperature of 20℃ as the calibration value, and obtain the average conductivity of the base material at each sampling ambient temperature. Step 4: Substitute the average conductivity of the base material at each sampling ambient temperature, the temperature compensation coefficient of the base material provided by the conductivity measuring instrument, and the sampling ambient temperature value into the average conductivity formula. Substitute the calibration value and the sampling ambient temperature value into the calibration value formula at 20℃. Combine the average conductivity formula at the same sampling ambient temperature value with the calibration value formula at 20℃ to obtain the actual temperature compensation coefficient at each sampling ambient temperature. Step 5: Take the average value of the actual temperature compensation coefficients under multiple sampling ambient temperatures to obtain the average temperature compensation coefficient; Step 6: Assign the average temperature compensation coefficient to the conductivity measuring instrument to achieve conductivity compensation; In step 4, the formula for the average conductivity is: ； In the formula, T 20 At 20℃, T 环境温度 For the sampled ambient temperature value, α 仪器 This refers to the temperature compensation coefficient of the base material in the conductivity measuring instrument. The conductivity value is the value at the sampling ambient temperature. In step 4, the calibration formula for 20℃ is: ； In the formula, α 实际 This is the actual temperature compensation coefficient; In step 6, the formula for compensating for conductivity is: ； In the formula, α is the average temperature compensation coefficient. This is the calibration value, where dT is the temperature difference between the actual temperature and 20℃. This represents the electrical conductivity value of the alloy sheet at temperature T.

2. The method for compensating for the conductivity testing of alloy plates under low-temperature conditions according to claim 1, characterized in that, There were three sampling ambient temperatures: 5℃, 10℃, and 15℃.

3. The conductivity testing and compensation method for alloy plates under low-temperature conditions according to claim 1, characterized in that, In step 1, the conductivity of each alloy plate is measured at multiple locations using a conductivity measuring instrument. Specifically: Ten points were selected on each alloy sheet: one point at each of the four corners, one point in the middle, and five points at the other locations excluding the corners and the middle. The conductivity of each alloy plate was measured at five points: the four corners and the middle.

4. The method for compensating for conductivity testing of alloy plates under low-temperature conditions according to claim 1, characterized in that, In step 1, the alloy sheet is made of aluminum alloy.

5. The method for compensating for the conductivity testing of alloy plates under low-temperature conditions according to claim 1, characterized in that, The conductivity measurement instrument used was a Horst 2.069 eddy current conductivity meter.

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