Method for evaluating cavitation erosion resistance of material

Abstract

The invention discloses a method for evaluating cavitation erosion resistance of a material. The method comprises the following steps: S1, carrying out a vibration cavitation erosion test on a target material according to an ASTM-G32 standard; s2, recording test data: recording the test data, including cumulative average cavitation erosion depth ([mu] m) and cumulative test duration (h), the cumulative average cavitation erosion depth being obtained by indirectly calculating cumulative mass damage amount (mg) according to an ASTM-G32 standard; s3, carrying out two-parameter Weibull distribution fitting and correction on the data in the S2; s4, the maximum cavitation erosion rate MER and the corresponding test moment tMER are calculated based on the ASTM-G32 standard; and S5, calculating the nominal cavitation erosion resistance time tin in combination with the tMER, and completing evaluation of the cavitation erosion resistance of the target material. The method is simple, short in consumed time, high in precision and high in practicability.

Description

Technical Field

[0001] The present invention relates to the technical field of evaluating the cavitation resistance performance of materials, and particularly to a method for evaluating the cavitation resistance performance of materials. Background Art

[0002] Cavitation refers to the phenomenon that bubbles in a liquid form and collapse under pressure changes, thereby causing impact and erosion on the material surface. This phenomenon widely exists in fluid environments such as hydraulic machinery, ship propellers, pumps, etc., seriously affecting the service life and safety of equipment. Therefore, studying and evaluating the cavitation resistance performance of materials has important practical significance.

[0003] Chinese Patent CN111610143B discloses a real-time detection system and method for cavitation tests of ship materials based on ultrasonic detection technology. However, it still relies on long-term ultrasonic cavitation experiments, and the test results are volatile, unable to ensure the accuracy of the test results;

[0004] Chinese Patent CN117629793A provides a method and system for evaluating the cavitation resistance performance of materials. Although quantitative evaluation can be achieved, it is only based on the physical properties of the materials, and the evaluation index is only the weight loss of material cavitation. In fact, the cavitation damage process is a complex process involving multiple disciplines, and there is currently no complete system.

[0005] Currently, the prior art cannot obtain the distribution law of the cavitation damage process, and the evaluation index is single. Summary of the Invention

[0006] Aiming at the deficiencies of the above prior art, the technical problem to be solved by this patent application is how to provide a method for evaluating the cavitation resistance performance of materials. Based on the ASTM-G32 test and its data, the method is simple, time-consuming, has high precision, strong engineering practicability, evaluates the cavitation resistance performance of the target material through multiple evaluation indexes, can be used for the comparative evaluation of the cavitation resistance performance between different materials, and this method is applicable to a variety of metal materials.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A method for evaluating the cavitation resistance performance of materials, comprising the following steps:

[0009] S1: Conduct a vibratory cavitation test on the target material according to the ASTM-G32 standard;

[0010] S2: Record the test data, including the cumulative average cavitation depth (μm) and the cumulative test duration (h), wherein the cumulative average cavitation depth is indirectly calculated from the cumulative mass damage amount (mg) according to the ASTM-G32 standard;

[0011] S3: Fit and correct the data in S2 with a two-parameter Weibull distribution. The model is:

[0012]

[0013] where F(t) is the cumulative average cavitation erosion depth (μm); t is the cumulative test duration (h); e represents the natural constant, dimensionless; η > 0 is the scale parameter, with the same unit as t; β > 1 is the shape parameter, dimensionless.

[0014] S4: Calculate the maximum erosion rate MER and its corresponding test time t_MER based on the ASTM-G32 standard.

[0015] S5: Calculate the nominal cavitation erosion resistance time t_in in combination with t_MER to complete the evaluation of the cavitation erosion resistance performance of the target material.

[0016] Among them, in S2, the recording of test data includes, but is not limited to, the following steps and methods:

[0017] S201: After the cavitation erosion test starts, record the data every 5 - 10 minutes.

[0018] S202: After the weight loss of the specimen due to cavitation erosion exceeds 0.1 mg, record the data every 3 - 5 minutes.

[0019] S203: The number of test data to be recorded after the weight loss of the specimen due to cavitation erosion exceeds 0.1 mg shall not be less than 10 groups.

[0020] Among them, in S4, the calculation and solution formula for the test time t_MER corresponding to the maximum erosion rate MER is:

[0021]

[0022] Among them, in S4, the calculation and solution formula for the cavitation erosion rate of the target material is:

[0023]

[0024] Among them, in S4, the calculation and solution formula for the maximum erosion rate MER is:

[0025]

[0026] Among them, in S5, the calculation and solution formula for the nominal cavitation erosion resistance time t_in is:

[0027]

[0028] In the formula,

[0029] In summary, the method for evaluating the cavitation erosion resistance of this evaluation material has the following beneficial effects:

[0030] 1. The method is based on the ASTM-G32 test and its data, with the advantages of simplicity, short time consumption, high precision, and strong engineering practicability;

[0031] 2. The cavitation damage distribution law of the target material can be obtained;

[0032] 3. Multiple evaluation indicators are used to evaluate the cavitation erosion resistance of the target material;

[0033] 4. It can be used for the comparative evaluation of the cavitation erosion resistance between different materials;

[0034] 5. This method is applicable to a variety of metal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flowchart of a method for evaluating the cavitation erosion resistance of a material according to the present invention.

[0036] Figure 2 It is a definition diagram of t_in and t_MER in the ASTM-G32 standard. DETAILED DESCRIPTION OF THE INVENTION

[0037] The present invention will be further described in detail below with reference to the drawings.

[0038] As Figure 1 shown, a method for evaluating the cavitation erosion resistance of a material includes the following steps:

[0039] S1: Conduct a vibratory cavitation test on the target material according to the ASTM-G32 standard;

[0040] S2: Record the test data, including the cumulative average cavitation depth (μm) and the cumulative test duration (h), where the cumulative average cavitation depth is indirectly calculated from the cumulative mass damage amount (mg) according to the ASTM-G32 standard;

[0041] S3: Fit and correct the data in S2 with a two-parameter Weibull distribution, and the model is:

[0042]

[0043] where F(t) is the cumulative average cavitation depth (μm); t is the cumulative test duration (h); e represents the natural constant, dimensionless; η>0 is the scale parameter, with the same unit as t; β>1 is the shape parameter, dimensionless;

[0044] S4: (1) Calculate the test time t_MER corresponding to the maximum cavitation rate MER according to the following formula:

[0045]

[0046] (2) Calculate the cavitation erosion rate of the target material according to the following formula:

[0047]

[0048] (3) Calculate the maximum cavitation erosion rate MER according to the following formula:

[0049]

[0050] S5: Calculate the nominal cavitation erosion resistance time t_in according to the following formula:

[0051]

[0052] In the formula,

[0053] Use the same method as above to obtain the cavitation erosion distribution laws, t_MER, MER, and t_in and other material cavitation erosion resistance performance evaluation indicators of target material 2, target material 3,..., target material n. It is recommended to evaluate according to the criterion that the larger the t_in, the better the material cavitation erosion resistance performance.

[0054] Based on the ASTM-G32 standard, perform two-parameter Weibull distribution fitting and correction on the test data (cumulative average cavitation erosion depth ∑ MDE (μm) and cavitation erosion cumulative test duration t (h)) of the obtained materials to obtain the distribution law in the initial stage of material cavitation erosion. Based on the ASTM-G32 standard, use the previously obtained distribution law to calculate the nominal cavitation erosion resistance time t_in, the maximum cavitation erosion rate MER, and the corresponding moment t_MER. Finally, evaluate the cavitation erosion resistance performance of the target material by comparing the magnitudes of the nominal cavitation erosion resistance times of different materials.

[0055] The technical solution of this patent is based on the test data of the ASTM-G32 standard to carry out fitting and correction of the cavitation erosion damage distribution law of the target material. On this basis, carry out numerical solution to obtain the cavitation erosion resistance performance evaluation indicators t_in, t_MER, and MER of the target material.

[0056] This patent is applicable to a variety of metal materials, such as aluminum, aluminum alloy, stainless steel AISI-316, duplex steel, nickel 200 alloy, tellurium copper alloy, nickel aluminum bronze, etc.

[0057] Description and reasoning process of the technical solution:

[0058] The cumulative distribution function of the two-parameter Weibull distribution is:

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] F(t) is defined as the cumulative average cavitation depth, and the cavitation rate is:

[0066]

[0067] To find MER, that is, F'(t) MAX Then continue to take the derivative of F'(t) to get:

[0068]

[0069] Let F”(t) = 0, then:

[0070] (1) β = 0, this scheme is not realistic;

[0071] (2) η = ∞, this scheme is not realistic;

[0072]

[0073]

[0074]

[0075]

[0076] Therefore, And the calculation formula for the maximum cavitation rate MER is:

[0077]

[0078] The definitions of the specimen t_in and t_MER in the ASTM-G32 standard are as Figure 2 shown. From Figure 2 it can be seen that:

[0079]

[0080]

[0081] Substitute the following obtained in the above text: and into the formula, and let to obtain:

[0082] From Figure 2 it can be seen that \(t_{in}=t_{MER}-\Delta t\). Substituting the result obtained above into this formula, we can obtain:

[0083]

[0084] Finally, it should be noted that those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and modifications.

Claims

1. A method for evaluating the cavitation erosion resistance of a material, characterized in that: The following steps are involved: S1: Perform vibration cavitation test on target materials according to ASTM-G32 standard; S2: record the test data, including the cumulative average cavitation depth (μm) and the cumulative test time (h), where the cumulative average cavitation depth is indirectly calculated from the cumulative mass damage (mg) according to the ASTM-G32 standard; S3: Fit and modify the data in S2 using a two-parameter Weibull distribution. The model is: Where, F(t) is the cumulative average cavitation depth (μm); t is the cumulative test time (h); e represents a natural constant, dimensionless; η>0 is a scale parameter, with the same unit as t; β>1 is a shape parameter, dimensionless; S4: Calculate the maximum cavitation rate MER and its corresponding test time t_MER based on the ASTM-G32 standard; S5: Calculate the nominal cavitation resistance time t_in in combination with t_MER to complete the evaluation of the cavitation resistance performance of the target material.

2. A method for evaluating the cavitation erosion resistance of a material according to claim 1, characterized in that: In S2, recording the test data includes but is not limited to the following steps and methods: S201: After the cavitation test begins, record data every 5-10 minutes; S202: After the cavitation weight loss of the sample exceeds 0.1 mg, record the data every 3-5 minutes; S203: After the cavitation weight loss of the sample exceeds 0.1 mg, no less than 10 groups of test data must be recorded.

3. The method for evaluating the cavitation erosion resistance of a material according to claim 1, characterized in that: In S4, the calculation formula for the test time t_MER corresponding to the maximum cavitation rate MER is:

4. The method for evaluating the cavitation erosion resistance of a material according to claim 1, characterized in that: In S4, the target material cavitation rate calculation formula is:

5. The method for evaluating the cavitation erosion resistance of a material according to claim 1, characterized in that: In S4, the calculation formula for the maximum cavitation rate MER is:

6. The method for evaluating the cavitation erosion resistance of a material according to claim 1, characterized in that: In S5, the calculation formula for the nominal cavitation resistance time t_in is: In the formula,

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