Method for testing stress corrosion susceptibility of additive manufacturing materials

Abstract

The present application relates to a kind of stress corrosion sensitivity test methods of additive manufacturing material, comprising the following steps: sampling in different directions of additive component, obtain several test samples;Under simulated test conditions, test sample is carried out stress corrosion simulation test, and the elongation δ 模 Under simulated environment is obtained;Under inert test environment, stress corrosion simulation test is carried out using the same test conditions with simulation test, and the elongation δ 惰 Under inert environment is obtained;According to the difference between the elongation δ 模 Under simulated environment and the elongation δ 惰 Under inert environment, the stress corrosion sensitivity I SCC The stress corrosion sensitivity evaluation method of component can consider the stress corrosion sensitivity weight of different directions respectively, and the stress corrosion sensitivity of component is obtained by comprehensive calculation, and the result obtained can effectively evaluate the stress corrosion sensitivity of additive manufacturing material, and the influence of anisotropy in additive manufacturing process is fully considered.

Description

Technical Field

[0001] This invention relates to the field of nuclear power, and more specifically, to a method for testing the stress corrosion susceptibility of additive manufacturing materials. Background Technology

[0002] Additive manufacturing technology has broad application prospects in the nuclear power field, enabling the rapid manufacturing of complex and precision components. It is particularly beneficial for emergency component replacement during nuclear power unit overhauls and for the production of small batches of complex workpieces. However, given the high level of safety considerations in nuclear power, additively manufactured components require effective evaluation before use.

[0003] Therefore, the research and development of aging evaluation methods for additive manufacturing nuclear power materials has a significant impact on the application of additive manufacturing technology in nuclear power plants. Only reliable evaluation methods can provide reliable support for the safe operation of nuclear power units and the improvement of economic efficiency.

[0004] In nuclear power plants, some commonly used metallic materials, such as low-alloy steel and stainless steel, are subjected to tensile stress and corrosion for extended periods, which can lead to stress corrosion cracking. For conventionally manufactured metal components, stress corrosion evaluation methods have been established and proven to be reliable.

[0005] However, additively manufactured parts have not yet been effectively evaluated. Due to their significant anisotropy, conventional evaluation methods cannot effectively evaluate them or conduct effective life assessments. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for testing the stress corrosion sensitivity of additive manufacturing materials, in view of the above-mentioned defects of the prior art.

[0007] The technical solution adopted by this invention to solve its technical problem is: to construct a method for testing the stress corrosion susceptibility of additive manufacturing materials, comprising the following steps:

[0008] Samples were taken from different directions of the additively manufactured parts to obtain several test samples;

[0009] Under simulated test conditions, stress corrosion simulation tests were conducted on the test samples to obtain the elongation δ under the simulated environment. 模 ;

[0010] Stress corrosion simulation tests were conducted under the same test conditions as the simulation tests in an inert environment to obtain the elongation δ under inert conditions. 惰 ;

[0011] Based on the elongation δ under the simulated environment 模 Elongation δ under inert environment 惰The difference leads to stress corrosion sensitivity I SCC .

[0012] In some embodiments, stress corrosion sensitivity I SCC The following formula is used to derive:

[0013]

[0014] Among them, I SCC To simulate stress corrosion sensitivity in an aquatic environment; δ 惰 Elongation under inert conditions; δ 模 This represents the elongation rate under simulated conditions.

[0015] In some embodiments, when sampling on an additive component, sampling is performed in different directions on the additive component.

[0016] In some embodiments, the center of the additive component is used as a reference, and the component is divided into two segments in the length direction and the width direction to form four regions. Samples are taken from the four regions in four different directions: the length direction, the width direction, and the four regions with a 45° offset on both sides of the length direction, to form a set of test samples.

[0017] In some embodiments, the test sample is in the form of a sheet or rod, and the test samples of each group are connected in series or in parallel, and the test samples are stretched at a set strain rate while being tested.

[0018] In some embodiments, when the test samples of each group are connected in series, if one test sample breaks during the test of each group of test samples, the test of that group ends, and the average value is calculated after at least three groups of test samples are tested effectively. When the test samples of each group are connected in parallel, all test samples of each group are broken, and the test of at least three groups of test samples is tested effectively.

[0019] In some embodiments, the sampled test sample is placed in a container for testing. Under simulated test conditions, the container contains a simulated solution, and under an inert environment, the container is filled with an inert gas.

[0020] In some embodiments, the following test conditions in the inert test environment are the same as those in the simulated test environment: test sample size, sampling method, and strain rate.

[0021] In some embodiments, when testing the sampled test samples in parallel, a comprehensive evaluation coefficient K is determined for the test samples sampled from each direction. i ;

[0022] K obtained i The value is multiplied by the ratio of the external stress to the total stress on the component to obtain the coefficient x for each sample taken from different orientations. ivalue;

[0023]

[0024] Where F i For the component stress in the sampling direction, F t This represents the total stress experienced by the component.

[0025] For x i The values ​​are normalized to obtain the final weight coefficient X. i :

[0026]

[0027] n represents the number of sampling directions on the additive component;

[0028] Weighted calculation of stress corrosion susceptibility of test samples in n directions I SCC-Q I SCC-Q =X1I1+X2+…+X n I n .

[0029] In some embodiments, K i The value of K depends on at least one of the following: the environmental specificity of the test sample location, the component thickness, and the degree of stress concentration. i The maximum value is 1, and the minimum value is 0.5. The harsher the environment and the more complex the stress on the component, the higher the value of K. i The larger the value, the better.

[0030] The stress corrosion susceptibility testing method for additive manufacturing materials according to the present invention has the following beneficial effects: The stress corrosion susceptibility evaluation method for components performs stress analysis on in-service components, considering the stress corrosion susceptibility weights in different directions, and performs comprehensive calculations to obtain the stress corrosion susceptibility of the component. The results obtained using this stress corrosion susceptibility evaluation method in different directions can effectively evaluate the stress corrosion susceptibility of additive manufacturing materials, fully considering the influence of anisotropy during the additive manufacturing process. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0032] Figure 1 This is a schematic diagram of the sampling location on the additive component in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of a tensile test performed on an important component;

[0034] Figure 3 This is a schematic diagram for tensile testing of general components;

[0035] Figure 4 This is a schematic flowchart of the stress corrosion sensitivity testing method for additive manufacturing materials according to the present invention. Detailed Implementation

[0036] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0037] The stress corrosion susceptibility testing method for additive manufacturing materials in a preferred embodiment of the present invention is used to evaluate the stress corrosion susceptibility of additive manufacturing materials.

[0038] Generally, a slow strain rate tensile method is used to evaluate stress sensitivity in a simulated environment. Before starting the stress corrosion sensitivity evaluation in the simulated environment, a stress corrosion simulation test is first conducted in an inert environment under the same conditions for subsequent stress corrosion sensitivity calculation. The inert environment test is consistent with the following stress corrosion test except for the environment, such as the size of the test sample 10, the sampling method, the strain rate, etc.

[0039] Specifically, the stress corrosion sensitivity testing method for additive manufacturing materials in this invention includes the following steps:

[0040] like Figure 1 As shown, samples were taken from different directions of the additive component 1 to obtain several test samples 10;

[0041] Under simulated test conditions, a stress corrosion simulation test was conducted on test sample 10, and the elongation δ under the simulated environment was obtained. 模 ;

[0042] Stress corrosion simulation tests were conducted under the same test conditions as the simulation tests in an inert environment to obtain the elongation δ under inert conditions. 惰 ;

[0043] Based on the stress corrosion sensitivity δ under simulated conditions 模 Elongation δ under inert environment 惰 The difference leads to stress corrosion sensitivity I SCC .

[0044] like Figure 1 As shown, when taking samples from the additive component 1 to obtain test samples 10, samples are taken from different directions of the additive component 1 to test the material properties of the additive component 1 in different directions.

[0045] In this embodiment, for each additively manufactured component, samples are taken from four different directions to form a set of test samples 10. Preferably, a star-shaped sampling pattern is selected, that is, taking the center of the additively manufactured component 1 as a reference, it is divided into two segments in the length direction and the width direction respectively, forming four regions. Samples are taken from the four regions in four different directions: the length direction, the width direction, and the four regions with a 45° deviation on both sides of the length direction. Test samples 10 are taken from each of the four different directions for testing. The sampling method is as follows: Figure 1 As shown, the test sample 10 can be in the shape of a sheet or a rod. Depending on the test requirements, samples can also be taken at every 30° or 20° deflection angle, and the number of samples must be at least three, usually four or more, to ensure that samples are taken in different directions.

[0046] Under simulated testing conditions, when conducting stress corrosion simulation tests on test sample 10, the sampled test samples 10 can be connected in series or parallel, and the test samples 10 are stretched at a set strain rate while being tested simultaneously to obtain the elongation δ under the simulated environment. 模 .

[0047] Typically, depending on the importance of the additive component 1, the selected test samples 10 are connected in series or in parallel. The method for determining the importance of a component is as follows: core components, components that may cause serious consequences after failure, and components that are difficult to replace or have high replacement costs are classified as important components; non-core components, components that are easy to replace, and components that have limited impact after failure are classified as general components.

[0048] like Figure 2 As shown, for critical components, each group of sampled components is typically connected in series and subjected to tensile testing at a set strain rate. When conducting stress corrosion susceptibility testing on critical components: for slow strain rate tensile testing, a strain rate of 10 is generally chosen for stainless steel. -6 / S order of magnitude, nickel-based alloys selected 10 -7 The strain rate is on the order of / S and can be adjusted according to the actual situation; the selection of the environment should be based on the actual situation of the components, and accelerated simulation experiments can be carried out appropriately, such as simulating seawater environment, high temperature and high pressure water environment, etc., and accelerated tests can be carried out as needed; different strain rates are selected according to the material grade and service condition, and four test samples 10 are connected in series under the same conditions (e.g., Figure 2 As shown), the test is conducted at a specified strain rate. Once a test sample 10 breaks during each test, the test group ends. After repeating the effective test of at least three groups of test samples 10, the average value is calculated.

[0049] Furthermore, under inert testing conditions, stress corrosion simulation tests were conducted on the critical components using the same test conditions as those used in the simulation tests of critical components, and the elongation δ under inert conditions was obtained. 惰.

[0050] Specifically, for critical components, the sampled test specimen 10 is placed inside a container 20 for testing under both simulated and inertial testing environments. Under simulated testing conditions, the container 20 contains a simulated solution, while under inertial conditions, the container 20 is filled with an inert gas. Furthermore, to minimize external factors in both testing environments, the following testing conditions are the same under the inertial testing environment as under the simulated testing environment: size of the test specimen 10, sampling method, and strain rate.

[0051] Based on the elongation δ of key components in a simulated environment 模 Elongation δ under inert environment 惰 The difference leads to stress corrosion sensitivity I SCC The stress corrosion sensitivity is calculated as shown in formula (1).

[0052]

[0053] Among them, I SCC To simulate stress corrosion sensitivity in an aquatic environment; δ 惰 Elongation under inert conditions; δ 模 This represents the elongation rate under simulated conditions.

[0054] like Figure 3 As shown, for general components, each group of sampled components is usually connected in parallel and subjected to tensile testing at a set strain rate.

[0055] When performing stress corrosion sensitivity testing on general components, the basic principles of the test method are consistent with those for critical components, including the selection of strain rate and environmental conditions; different strain rates are selected according to the material grade and service condition, and four test samples 10 are tested in parallel under the same conditions. Figure 3 As shown, the test is conducted at a specified strain rate. During the test, all four test samples 10 must be broken. The test is repeated for at least three sets of test samples 10 before the test ends.

[0056] Specifically, for general components, in both simulated and inertial testing environments, the sample 10 is placed in a container 20 for testing. Under simulated testing conditions, the container 20 contains a simulated solution, while under inertial conditions, the container 20 is filled with an inert gas. Furthermore, to minimize external factors in both testing environments, the following testing conditions are the same in the inertial testing environment as in the simulated testing environment: sample 10 size, sampling method, and strain rate.

[0057] The stress corrosion susceptibility assessment method for components involves stress analysis of in-service components, considering the stress corrosion susceptibility weights in different directions, and performing comprehensive calculations to obtain the component's stress corrosion susceptibility. The results obtained using this method can effectively evaluate the stress corrosion susceptibility of additive manufacturing materials, fully considering the anisotropy effects during the additive manufacturing process.

[0058] Specifically, for the testing and evaluation of important components, the stress corrosion sensitivity of the material is calculated based on the fastest fracture. The calculated results are compared and analyzed with those of materials under inert conditions, i.e., the formula in formula (1). Under repeatable conditions, the average value of the three test samples 10 is calculated.

[0059] For the evaluation of general components, the stress corrosion sensitivity is calculated using formula (1). Under the condition of ensuring repeatability, the average value of three samples of test sample 10 taken from the same location is calculated to obtain the stress corrosion sensitivity results for each group of four test samples 10. The stress corrosion sensitivity of the four test samples 10 obtained from different sampling methods is then comprehensively weighted to evaluate the stress corrosion sensitivity of the component. The calculation process is as follows:

[0060] K obtained i The value is multiplied by the ratio of the external stress to the total stress on the component to obtain the coefficient x for each sample taken from different orientations. i value;

[0061]

[0062] Where F i For the component stress in the sampling direction, F t This represents the total stress experienced by the component.

[0063] For x i The values ​​are normalized to obtain the final weight coefficient X. i :

[0064]

[0065] n is the number of sampling directions on the additive component 1. In this embodiment, n is 4.

[0066] Weighted calculation of stress corrosion susceptibility of test sample 10 in n directions I SCC-Q ,

[0067] I SCC-Q =X1I1+X2+…+X n I n (Formula 4).

[0068] In some embodiments, Ki The value of K depends on at least one of the following: the environmental specificity of the test sample location, the component thickness, and the degree of stress concentration. i The maximum value is 1, and the minimum value is 0.5. The harsher the environment and the more complex the stress on the component, the higher the value of K. i The larger the value, the better.

[0069] Combination Figure 4 As shown, the following is an example of an additively manufactured part under complex stress conditions, to evaluate its stress corrosion susceptibility. The steps are as follows:

[0070] (1) Conduct a detailed investigation and analysis of the stress conditions and service environment of the components;

[0071] (2) Samples of stress corrosion test sample 10 were taken from the component and samples were taken from four directions respectively;

[0072] (3) Conduct stress corrosion tests in an inert environment to obtain elongation in four directions (if it is a critical component, the test in a simulated environment can be conducted before the test in an inert environment, and only the first fracture test sample 10 needs to be tested).

[0073] (4) Determine the importance of the component (steps 5-7 are for important components, and steps 8-11 are for general components);

[0074] (5) Conduct a series stress corrosion test on four test samples 10, repeating it three times. For test samples 10 with poor repeatability, the number of repetitions needs to be increased.

[0075] (6) The stress corrosion susceptibility of the material that fractures first is calculated using Formula 1;

[0076] (7) Calculate the average value of the stress corrosion susceptibility of the three groups of materials and use it as the stress corrosion susceptibility of the component or test sample 10.

[0077] (8) Conduct parallel stress corrosion tests on four test samples 10. The test can only be completed after all four test samples 10 have been tested. Repeat the test three times. For test samples 10 with poor repeatability, the number of repetitions needs to be increased.

[0078] (9) The stress corrosion susceptibility of each test sample 10 is calculated using Formula 1, and the average value of each test sample 10 is obtained.

[0079] (10) Determine the comprehensive evaluation coefficient K in four different directions based on the stress state of the component. i The weighting coefficient x is calculated according to formulas (2) and (3). i and X i ;

[0080] (11) The weighted stress corrosion susceptibility I of the component is calculated according to formula (4). SCC-Q .

[0081] Understandably, the above-mentioned technical features can be used in any combination without restriction.

[0082] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for testing the stress corrosion susceptibility of additively manufactured materials, characterized in that, Includes the following steps: Samples were taken from different directions of the additive component (1) to obtain several test samples (10). Connect the test samples (10) from each group in parallel; Under simulated test conditions, a stress corrosion simulation test was conducted on the test sample (10) to obtain the elongation under the simulated environment. ; Stress corrosion simulation tests were conducted under the same test conditions as the simulation tests in an inert testing environment to obtain the elongation under inert conditions. ; Based on the elongation rate under the simulated environment Elongation under inert environment The difference leads to stress corrosion sensitivity ; When using parallel testing, the stress corrosion susceptibility of the test sample (10) in different directions is considered separately. The weights are used to perform comprehensive calculations to obtain the stress corrosion susceptibility of the additive component (1); When the sampled test samples (10) are tested in parallel, the comprehensive evaluation coefficient of the test samples (10) sampled in each direction is determined. K i ; Obtained K i The value is multiplied by the ratio of the external stress to the total stress on the component to obtain the coefficient x for each sample taken from different orientations. i value; (Official 2) Where F i For the component stress in the sampling direction, F t This represents the total stress experienced by the component. right x i The values ​​are normalized to obtain the final weight coefficients. X i : (Official 3) n is the number of sampling directions on the additive component (1); Weighted calculation of stress corrosion susceptibility of test sample (10) in n directions. I SCC-Q , ; K i The value depends on at least one of the following: the environmental specificity of the test sample (10) location, the component thickness, and the degree of stress concentration. K i The maximum value is 1, and the minimum value is 0.

5. The harsher the environment and the more complex the stress on the component, the higher the value of K. i The larger the value, the better.

2. The method for testing the stress corrosion sensitivity of additive manufacturing materials according to claim 1, characterized in that, Stress corrosion sensitivity The following formula is used to derive: (Official 1); in, To simulate stress corrosion sensitivity in an ambient aquatic environment; Elongation under inert conditions; This represents the elongation rate under simulated conditions.

3. The method for testing the stress corrosion sensitivity of additive manufacturing materials according to claim 1, characterized in that; When sampling on the additive component (1), samples are taken in different directions of the additive component (1).

4. The method for testing the stress corrosion sensitivity of additive manufacturing materials according to claim 3, characterized in that, Using the center of the additive component (1) as a reference, it is divided into two sections in the length direction and the width direction to form four regions. Samples are taken from the four regions in four different directions: the length direction, the width direction, and the four regions with a 45° deviation on both sides of the length direction to form a set of test samples (10).

5. The method for testing the stress corrosion sensitivity of additive manufacturing materials according to claim 3 or 4, characterized in that, The test sample (10) is in the form of a sheet or a rod. The test sample (10) is stretched at a set strain rate and tested simultaneously.

6. The method for testing the stress corrosion sensitivity of additive manufacturing materials according to claim 5, characterized in that, When the test samples (10) of each group are connected in parallel, all test samples (10) of each group are broken, and at least three groups of test samples (10) are tested effectively.

7. The method for testing the stress corrosion sensitivity of additive manufacturing materials according to claim 5, characterized in that, The sampled test sample (10) is placed in a container (20) for testing. Under simulated test conditions, the container (20) contains a simulated solution. Under inert conditions, the container (20) is filled with inert gas.

8. The method for testing the stress corrosion sensitivity of additive manufacturing materials according to claim 7, characterized in that, The following test conditions under the inert test environment are the same as those under the simulated test environment: test sample (10) size, sampling method, strain rate.

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