Method for indentation measurement of brinell hardness

Abstract

This invention discloses a method for measuring Brinell hardness by indentation, comprising: S1, selecting two hardness standards, wherein the hardness value of the sample to be tested is within H... BW 1 and H BW Between 2; S2, use the sample to be tested to perform indentation testing on the testing machine to obtain the corresponding maximum indentation depth h. max 1. h max 2. The test load F is used to calculate the indentation depths h1 and h2; S3. Using h1, h2, and h max 1. h max 2. Based on F, two sets of stiffness data K1 and K2 of the testing machine are obtained; S4. Based on K1 and K2, the corrected stiffness K of the testing machine is obtained. m S5. Obtain the maximum indentation depth h of the sample to be tested. max 3. According to h max 3. K m Obtain the corrected indentation depth h3; S6, derive the Brinell hardness H of the sample based on h3. BW 3. By incorporating the above measurement methods into a program, automated stiffness correction and automated hardness testing can be achieved.

Description

Technical Field

[0001] This invention relates to a method for measuring Brinell hardness by indentation. Background Technology

[0002] Generally speaking, the hardness of a material characterizes its ability to resist deformation. In static indentation hardness tests, the main types are Brinell hardness, Vickers hardness, and Rockwell hardness. There are certain empirical conversion relationships between the values ​​of these three types, and the hardness value is related to the yield strength and tensile strength of the material. Therefore, hardness testing is widely used in material testing.

[0003] Brinell hardness indentation is performed by pressing a spherical indenter with a certain radius into the sample surface. The surface area of ​​the indentation is calculated using the average diameter of the indentation and the diameter of the indenter. Currently, Brinell hardness testing machines mainly include conventional Brinell hardness testing machines and rapid Brinell hardness testing machines. Conventional Brinell hardness testing machines provide reliable measurement results with better comparability, but they have disadvantages such as requiring an additional optical measurement system and having low efficiency in indentation diameter measurement. Rapid Brinell hardness testing machines, while having the advantages of not requiring an optical measurement system and high efficiency, also suffer from poor comparability of measurement results. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the problems of unreliable measurement results and poor comparability in the prior art, and to provide a method for measuring Brinell hardness by indentation.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] A method for measuring Brinell hardness by indentation, the method comprising:

[0007] S1. Select two hardness standards, with the lower hardness value being H. BW 1. The one with the higher hardness value is H. BW 2. The hardness value of the sample to be tested is within H. BW 1 and H BW Between 2;

[0008] S2. Using the two hardness standards mentioned above, an indentation test is performed on the testing machine to obtain H. BW 1 and H BW 2 corresponds to the maximum indentation depth h max 1. h max 2 and test load F, H BW 1. Substitute the test load F into the relationship between indentation depth, test load, and hardness value (i.e., Relationship 1) to obtain the indentation depth h1. Then, calculate H... BW 2. Substitute the test load F into relation 1 to obtain the indentation depth h2;

[0009] S3, h1, h during testing max Substituting the test load F into the relationship between the stiffness of the testing machine, the maximum indentation depth, the indentation depth, and the test load F (i.e., relationship two), we obtain the stiffness K1 of the testing machine. Then, we consider h2 and the h during the test... max Substituting the test load F into relation 2, we obtain the stiffness K2 of the testing machine;

[0010] S4. Based on K1 and K2, the corrected stiffness K of the testing machine is obtained. m ;

[0011] S5. Perform an indentation test on the test sample using the testing machine to obtain the maximum indentation depth h of the test sample. max 3. Based on the corrected stiffness K m The corrected indentation depth h3 is obtained;

[0012] S6. Substitute the corrected indentation depth h3 and test load F into relation one to obtain the hardness value H of the sample to be tested. BW 3.

[0013] In this technical solution, the Brinell hardness distribution of a material can be characterized through automatic measurement. A standard hardness block is used to correct the stiffness of the indentation testing machine, solving the problem of difficulty in obtaining the stiffness of the indentation testing machine. Automatic measurement of Brinell hardness is achieved, overcoming the time-consuming and costly nature of manual measurement. This method uses the obtained hardness from the testing machine for inverse iteration, exhibiting good consistency with Brinell hardness measured by conventional optical systems and possessing traceability. The method for obtaining the stiffness of the testing machine and the subsequent Brinell hardness calculation method are inverse operations, ensuring the reliability of the test results.

[0014] Preferably, in step S5, the h of the sample to be tested is... max 3. The corrected stiffness K m Substitute the test load F into the second relationship to obtain the corrected indentation depth h3.

[0015] Preferably, relation one, i.e., formula (1):

[0016]

[0017] Where F is the test load, H BW denoted as hardness value, h as indentation depth, and D as the diameter of the cemented carbide ball used in the indentation test on the testing machine.

[0018] Preferably, relation two, i.e., formula (2):

[0019] h = h max -F / K

[0020] Where h is the indentation depth, h maxThe maximum indentation depth of the sample measured on the testing machine is denoted by F, where F is the test load and K is the stiffness of the testing machine.

[0021] Preferably, in step S4, according to formula (3):

[0022] K m = (K1+K2) / 2

[0023] Substituting K1 and K2, we obtain the corrected stiffness K. m .

[0024] The positive and progressive effects of this invention are as follows:

[0025] The indentation method for measuring Brinell hardness can automatically characterize the Brinell hardness distribution of a material, thus solving the problems of time-consuming and costly manual Brinell hardness measurement. This method uses the hardness obtained from the testing machine for inverse iteration, and shows good consistency with the Brinell hardness measured by conventional optical systems, while also providing traceability. The method for determining the stiffness of the testing machine and the subsequent Brinell hardness calculation are inverse operations, ensuring the reliability of the test results. Attached Figure Description

[0026] Figure 1 This is a step diagram of the method for measuring Brinell hardness by indentation according to the present invention. Detailed Implementation

[0027] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments.

[0028] like Figure 1 As shown, this invention discloses a method for measuring Brinell hardness by indentation. The method for measuring Brinell hardness by indentation includes:

[0029] S1. Select two hardness standards, with the lower hardness value being H. BW 1. The one with the higher hardness value is H. BW 2. The hardness value of the sample to be tested is within H. BW 1 and H BW Between 2;

[0030] S2. Using the two hardness standards mentioned above, an indentation test is performed on the testing machine to obtain H. BW The maximum indentation depth h corresponding to 1 max 1, H BW 2 corresponds to the maximum indentation depth h max 2, and the test load F, will H BW 1. Substituting the test load F into formula (1) representing the relationship between indentation depth and test load and hardness value, we obtain the indentation depth h1. Then, we use H... BW2. Substitute the test load F into formula (1) to obtain the indentation depth h2;

[0031] S3, take h1 and the test result h max Substituting 1 and the test load F into formula (2) which represents the relationship between the stiffness of the testing machine, the maximum indentation depth, the indentation depth, and the test load F, we obtain the stiffness K1 of the testing machine. Then, we calculate h2 and h during the test. max Substituting 2 and the test load F into formula (2), the stiffness K2 of the testing machine is obtained;

[0032] S4. Substitute K1 and K2 into formula (3) to obtain the corrected stiffness K of the testing machine. m ;

[0033] S5. Perform an indentation test on the test sample using the testing machine to obtain the maximum indentation depth h of the test sample. max 3. The h of the sample to be tested max 3. Correction of stiffness K m Substitute the test load F into formula (2) to obtain the corrected indentation depth h3;

[0034] S6. Substitute the corrected indentation depth h3 and test load F into formula (1) to obtain the hardness value H of the sample to be tested. BW 3.

[0035] Steps S2 and S3 are for measuring two sets of data for the stiffness K of the testing machine; step S4 is for obtaining the corrected stiffness K of the testing machine based on the multiple sets of stiffness data obtained from the tests. m Step S5 is based on the corrected stiffness K. m The maximum indentation depth h obtained by testing the sample on the testing machine. max 3. Obtain the corrected indentation depth h3 of the test sample through reverse iteration; Step S6 is to calculate the Brinell hardness H of the test sample based on the corrected indentation depth h3 through reverse iteration. BW 3.

[0036] Specifically, formula (1):

[0037]

[0038] Where F is the test load, H BW denoted as hardness value, h as indentation depth, and D as the diameter of the cemented carbide ball used in the indentation test on the testing machine. The test load F and diameter D are known experimental parameters during the test.

[0039] Formula (2):

[0040] h = h max -F / K

[0041] Where h is the indentation depth, h max The maximum indentation depth of the sample measured on the testing machine is denoted by F, where F is the test load and K is the stiffness of the testing machine.

[0042] In step S3, the test load F is a known value, and h = h1, h max =h max Substituting into formula (2), we get K = K1, and h = h2, h max =h max Substituting into formula (2), we get K = K2.

[0043] Formula (3):

[0044] K m = (K1+K2) / 2

[0045] In step S5, h max =h max 3. K = K m Substituting into formula (2), we get h = h3.

[0046] In step S6, substituting h = h3 into formula (1) yields H. BW =H BW 3.

[0047] By incorporating the above calculation methods into a program, automated stiffness correction and automated hardness testing can be achieved. The Brinell hardness distribution of the material is characterized through automatic measurement, realizing automated Brinell hardness measurement and solving the problems of time-consuming and costly manual Brinell hardness measurement. This method uses the hardness obtained from the testing machine for inverse iteration, and shows good consistency with the Brinell hardness measured by conventional optical systems, while also possessing traceability. The method for obtaining the stiffness of the testing machine and the subsequent Brinell hardness calculation method are inverse operations, ensuring the reliability of the test results.

[0048] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for measuring Brinell hardness by indentation, characterized in that, The method for measuring Brinell hardness by indentation includes: S1, select two hardness standards, the smaller hardness value is H BW 1 1, the larger hardness value is H BW 2 2, the hardness value of the sample to be measured is between H BW 1 and H BW 2 S2, using the two hardness standards above to carry out indentation test on the testing machine to obtain H BW 1 and H BW 2 corresponding maximum indentation depth h max 1, h max 2 and test load F, and H BW 1, test load F is substituted into the relationship between indentation depth and test load and hardness value, i.e. relationship one, to obtain indentation depth h1, and H BW 2, test load F is substituted into relationship one to obtain indentation depth h2; S3, h1, h during testing max Substituting the test load F into the relationship between the stiffness of the testing machine, the maximum indentation depth, the indentation depth, and the test load F (i.e., relationship two), we obtain the stiffness K1 of the testing machine. Then, we consider h2 and the h during the test... max Substituting the test load F into relation 2, we obtain the stiffness K2 of the testing machine; S4. Based on K1 and K2, the corrected stiffness K of the testing machine is obtained. m ; S5. Perform an indentation test on the test sample using the testing machine to obtain the maximum indentation depth h of the test sample. max 3. Based on the corrected stiffness K m The corrected indentation depth h3 is obtained; S6. Substitute the corrected indentation depth h3 and test load F into relation one to obtain the hardness value H of the sample to be tested. BW 3.

2. The method for measuring Brinell hardness by indentation as described in claim 1, characterized in that, In step S5, the h of the sample to be tested is... max 3. The corrected stiffness K m Substitute the test load F into the second relationship to obtain the corrected indentation depth h3.

3. The method for measuring Brinell hardness by indentation as described in claim 1 or 2, characterized in that, Relationship 1, i.e., formula (1): Where F is the test load, H BW denoted as hardness value, h as indentation depth, and D as the diameter of the cemented carbide ball used in the indentation test on the testing machine.

4. The method for measuring Brinell hardness by indentation as described in claim 3, characterized in that, Relationship 2, i.e., formula (2): h=h max -F / K Where h is the indentation depth, h max The maximum indentation depth of the sample measured on the testing machine is denoted by F, where F is the test load and K is the stiffness of the testing machine.

5. The method for measuring Brinell hardness by indentation as described in claim 2, characterized in that, In step S4, according to formula (3): K m =(K1+K2) / 2 Substituting K1 and K2, we obtain the corrected stiffness K. m .

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