Corrosion-resistant titanium alloy impact absorbing energy prediction method based on double-sided press-in

Abstract

The invention provides a method for predicting the impact absorbing energy of a corrosion-resistant titanium alloy based on double-sided press-in, which comprises the following steps of: testing a titanium alloy material sample by adopting a double-sided press-in method, introducing an indentation-type gap through primary press-in, then carrying out secondary reverse press-in to fracture the sample, and calculating the impact absorbing energy according to press-in fracture energy, so as to predict the impact absorbing energy of the corrosion-resistant titanium alloy. The impact absorbing energy of the micro corrosion-resistant titanium alloy sample can be accurately detected, and the performance evaluation efficiency of the corrosion-resistant titanium alloy material in the design and development process is improved; impact performance evaluation of a series of temperatures can be achieved through the micro-size raw materials in titanium alloy material design and process research and development, the research and development speed of the titanium alloy material can be remarkably increased, and the cost can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical property detection of metal materials, and in particular to a method for predicting impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing. Background Art

[0002] Titanium alloys have the advantages of high specific strength and good corrosion resistance, and are widely used in the fields of shipbuilding, aerospace, etc. For titanium alloys used as structural materials, a large number of mechanical property tests need to be carried out during the design and development process. The high price of titanium alloy materials themselves causes a sharp increase in the cost of testing. The impact absorption energy measured by the Charpy impact test is a key indicator for evaluating the brittle fracture resistance of notched specimens. For titanium alloy materials used in hull structures and pressure-resistant structures, impact testing is an indispensable test item in material research and development and performance evaluation. Impact testing requires testing at multiple temperatures from room temperature to low temperature, and at least three specimens are required at a single temperature. Therefore, traditional impact specimens require the processing of a large number of specimens. In order to speed up the development of new titanium alloy materials and reduce costs, the method of melting small blocks is generally used for process screening. As a result, there is a need to replace traditional specimens with tiny specimens to evaluate the impact absorption energy of titanium alloy materials in order to improve efficiency and reduce costs.

[0003] Patent publication number CN117451539A discloses a method and device for intelligently testing the impact properties of titanium alloy forging blanks. This method is used in the manufacturing of aviation ring forgings. The specific implementation scheme includes: impacting the blank to be tested using a testing machine to obtain the blank after the impact; photographing the cross-section of the blank after the impact using an image acquisition module to obtain a cross-sectional image; inputting the cross-sectional image into a pre-trained image classification model, which outputs a classification result for the cross-sectional image, including whether the cross-sectional image is qualified or unqualified; and determining the impact performance test result of the blank to be tested based on the classification result. This device is relatively complex in structure and also requires large-scale specimens for testing, making it impossible to test and screen small pieces. Summary of the Invention

[0004] In view of this, the present invention aims to propose a method for detecting the impact absorption energy of micro corrosion-resistant titanium alloy specimens based on the indentation method, so as to realize rapid, accurate and low-cost testing and prediction of the impact performance of titanium alloy materials, improve the performance evaluation efficiency of corrosion-resistant titanium alloy materials in the design and development process; and reduce R&D costs.

[0005] The present invention discloses a method for predicting the impact absorbed energy of a corrosion-resistant titanium alloy based on double-sided pressing, comprising the following steps:

[0006] Step S1: Sample preparation: Prepare a sample for the press-in test according to a preset size;

[0007] Step S2: First indentation test: using a conical indenter to indent the first surface of the sample to a first preset depth, maintaining the indenter for a first preset time, and then unloading to obtain a first load-depth curve during the indentation process;

[0008] Step S3: Second indentation test: Use a spherical indenter to indent the second surface of the sample until the sample breaks, with the first surface and the second surface being opposite surfaces, and obtain a second load-depth curve during the indentation process;

[0009] Step S4: Calculate the impact absorption energy of the test material according to formula (1):

[0010] (1)

[0011] Among them, α I is the impact absorption energy, W k is the equivalent indentation fracture energy, β v is the indentation notch coefficient, E is the elastic modulus of the test material, σ y is the yield strength of the material being tested, n is the strain hardening exponent of the material being tested; β v It can be obtained by the first load-depth curve in step S2, W k It can be obtained through the second load-depth curve in step S3, E, σ y , n can be obtained through the press-in test in step S2 and / or step S3, respectively.

[0012] Furthermore, the sample is a micro sample.

[0013] Furthermore, the length of the sample is 4-6 mm, the width is 0.8-1.2 mm, and the height is 0.8-1.2 mm.

[0014] Furthermore, step S2 includes:

[0015] Step S21: placing the sample 2 on the instrumented pressing device, with the pressing plate 3 supporting the lower side of the second surface of the sample 2, and the sample 2 and the pressing plate 3 being in rigid contact;

[0016] Step S22: using a conical indenter 1 with a vertex angle of θ to press down on the first surface of the sample 2, with the center of the indenter aligned with the center of the first surface of the sample 2;

[0017] Step S23: pressing the depth to a first preset depth;

[0018] Step S24: Unloading after maintaining the first preset time to obtain a first load-depth curve during the pressing process.

[0019] Furthermore, the first preset depth is 160-240 μm.

[0020] Furthermore, the pressing speed of the first pressing test was 0.2~0.4mm / min.

[0021] Further, according to the first load-depth curve in step S2, β v include:

[0022] The indentation notch depth h is obtained by formula (2): v :

[0023] (2)

[0024] Among them, h max is the maximum indentation depth, α is the indentation coefficient, P max1 is the maximum load when the conical indenter 1 is pressed in, and S is the slope of the first preset interval in the unloading section of the first load-depth curve;

[0025] On this basis, the indentation notch coefficient β is obtained by formula (3): v :

[0026] (3)

[0027] Where l1 is the length of the short side of the first surface, l2 is the length of the long side of the first surface, v is the Poisson's ratio of the tested material, C1 and C2 are intermediate parameters, C1 is obtained by formula (4), and C2 is obtained by formula (5):

[0028] (4)

[0029] (5).

[0030] Furthermore, the first preset interval refers to 0.6P max1 ~0.95P max1 .

[0031] Furthermore, step S3 includes:

[0032] Step S31: placing the sample on two supports, with the second surface of the sample facing upward, and the top ends of the two supports in point contact with the first surface of the upper sample, with the indentation notch of the sample located at the center of the distance between the two supports;

[0033] Step S32: using a spherical indenter with an indenter radius of R to press into the second surface of the sample, with the indentation center of the spherical indenter corresponding to the center of the indentation notch;

[0034] Step S33: Press the sample until it breaks, and obtain a second load-depth curve during the pressing process.

[0035] Further, the equivalent indentation fracture energy W is obtained according to the second load-depth curve in step S3. k include:

[0036] According to formula (6), the total equivalent energy U is obtained t :

[0037] (6)

[0038] Among them, U y U is the area of the curve from the load zero point to the load yield point (the point where the load depth curve changes from the straight rising part to the curve rising part), ym is the curve area from the load yield point to the load maximum point, U m is the area of the curve after the maximum load point;

[0039] According to formula (7), the secondary compression equivalent modulus E of the tested material is obtained i :

[0040] (7)

[0041] Among them, L s is the distance between the two support members 4, l1 is the length of the short side of the first surface, l2 is the length of the long side of the first surface, ΔF and Δh are the maximum load values F reached in the second press-in test m Before, the load difference and depth difference corresponding to any two points in the rising section of the second load-depth curve;

[0042] On this basis, the equivalent indentation fracture energy W is obtained by formula (8): k :

[0043] (8)

[0044] Where v is the Poisson's ratio of the material being tested.

[0045] Compared with the existing technology, the corrosion-resistant titanium alloy impact absorbed energy prediction method based on double-sided pressing described in the present invention has the following advantages:

[0046] (1) The present invention adopts a double-sided pressing method to test micro titanium alloy material samples. An indentation notch is introduced by the first pressing, and then a second reverse pressing is performed to fracture the sample. The impact absorption energy is calculated based on the pressing fracture energy. This method can more accurately detect the impact absorption energy of micro corrosion-resistant titanium alloy samples, thereby improving the performance evaluation efficiency of corrosion-resistant titanium alloy materials in the design and development process.

[0047] (2) The impact absorption energy of titanium alloy materials can be tested using tiny specimens, and the impact performance evaluation of a series of temperatures can be achieved using tiny raw materials in the design and process development of titanium alloy materials, which can significantly increase the development speed of titanium alloy materials and reduce costs;

[0048] (3) For titanium alloy structural materials that have been in service for a long period of time, the above-mentioned test can be used to perform micro-destructive sampling to test their current impact properties, providing key data for the in-service safety evaluation and remaining life assessment of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 Schematic diagram of the process of the method for detecting the impact absorbed energy of corrosion-resistant titanium alloy according to an embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of the first pressing in the method for detecting the impact absorbed energy of corrosion-resistant titanium alloy according to an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the second pressing in the method for detecting the impact absorbed energy of corrosion-resistant titanium alloy according to an embodiment of the present invention;

[0053] Figure 4 Schematic diagram of various regions on a load-depth curve when calculating equivalent indentation fracture energy in a method for detecting impact absorbed energy of a corrosion-resistant titanium alloy according to an embodiment of the present invention;

[0054] Figure 5 This is the load-depth curve of the conical indenter penetrating the TC4 material in the method for detecting the impact absorbed energy of the corrosion-resistant titanium alloy described in an embodiment of the present invention.

[0055] Description of reference numerals:

[0056] 1. Conical indenter; 2. Specimen; 3. Pressure plate; 4. Support; 5. Spherical indenter. DETAILED DESCRIPTION

[0057] In order to make the technical means, objectives and effects of the present invention easier to understand, embodiments of the present invention are described in detail below with reference to specific figures.

[0058] It should be noted that all terms used in the present invention to indicate direction and position, such as "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "low", "lateral", "longitudinal", "center", etc., are only used to explain the relative positional relationship and connection status between the various components in a certain specific state (as shown in the accompanying drawings). They are only for the convenience of describing the present invention, and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0059] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical connections; direct connections or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0060] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0061] Instrumented indentation technology is a non-destructive mechanical property testing technology developed in recent years that is suitable for tiny specimens or in-service materials. The indenter is driven by a motor and pressed vertically into the surface of the material being tested. Single or multiple loading and partial unloading cycles are performed at the same point of action. The indentation depth and load are measured, and a mechanical constitutive relationship model of the material is established. This is then correlated with the material's mechanical properties such as tensile strength, yield strength, elastic modulus, and strain hardening index. Compared to hardness testing, instrumented indentation technology can achieve high-throughput mechanical property testing with high accuracy. It is also non-destructive and efficient. It has good application prospects in impact testing of titanium alloy materials.

[0062] Through literature search, no method for testing the impact absorption energy of metal materials based on instrumented indentation technology was found. The methods for testing the impact absorption energy of metal materials based on instrumented indentation technology mainly use a spherical indenter to test the material and calculate the fracture toughness J of the material based on the indentation work or energy. IC , and then J IC Convert to K IC , then using fracture toughness as an intermediate parameter, the fracture toughness is converted into impact energy. The above method has the following problems: (1) It is necessary to use the fracture toughness obtained by the indentation test for secondary conversion, and the fracture toughness value measured by the indentation test itself has a certain error, and the secondary conversion leads to error amplification; (2) The conversion between fracture toughness and impact absorbed energy requires the use of empirical formulas, and different empirical coefficients need to be established for different materials, which has poor applicability; (3) The existing indentation test does not cause the specimen to fracture, and the specimen does not contain a notch. In principle, it is impossible to explain the development process of crack generation at the notch root, crack expansion, and fracture of the notched specimen under external load.

[0063] like Figure 1-5 As shown, the present invention discloses a method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing, comprising the following steps:

[0064] Step S1: Sample preparation: Prepare a sample 2 for the press-in test according to a preset size;

[0065] Step S2: First indentation test: using the conical indenter 1 to indent the first surface of the sample 2 to a first preset depth, maintaining the indenter for a first preset time, and then unloading to obtain a first load-depth curve during the indentation process;

[0066] Step S3: Second indentation test: The spherical indenter 5 is used to indent the second surface of the sample 2 until the sample breaks, with the first surface and the second surface being opposite surfaces, and a second load-depth curve is obtained during the indentation process;

[0067] Step S4: Calculate the impact absorption energy of the test material according to formula (1):

[0068] (1)

[0069] Among them, α I is the impact absorption energy, W k is the equivalent indentation fracture energy, β v is the indentation notch coefficient, E is the elastic modulus of the test material, σ y is the yield strength of the material being tested, n is the strain hardening exponent of the material being tested; β v It can be obtained by the first load-depth curve in step S2, W kIt can be obtained through the second load-depth curve in step S3, E, σ y , n can be obtained through the press-in test in step S2 and / or step S3, respectively.

[0070] In this example, an indentation notch is pre-made on the first side of the sample 2 by the first indentation test, and the sample 2 is fractured by the second indentation test, so that the equivalent impact absorption energy can be calculated by the fracture energy of the indentation process, thereby realizing a rapid and efficient evaluation of the impact properties of the titanium alloy material by the instrumented indentation method. It should be noted that the first side of the sample 2 refers to the surface formed by the length and height of the sample 2, and the length of the sample 2> the width=the height. In this example, the sample 2 is a miniature sample, the length of the sample 2 is 4~6mm, the width is 0.8~1.2mm, and the height is 0.8~1.2mm. Preferably, the size of the sample 2 is 5.0×1.0×1.0mm. When preparing the sample 2 in step S1, a block with a size slightly larger than the preset size is first cut from the corrosion-resistant titanium alloy raw material by wire cutting, and then the size of the sample 2 is ground and polished to the preset size, and its surface roughness meets the preset roughness requirements. As a specific example, the preset size of the sample 2 is 5.0×1.0×1.0mm, the preset roughness Ra≤0.8, and the size of the cut block is 5.0×1.1×1.1mm. After grinding and polishing, its size reaches the preset size, and the surface roughness of the sample 2 is less than or equal to 0.8. In the above example, the first and second surfaces of the sample 2 are respectively the surfaces formed by one of the length and height, that is, the 5.0×1.0mm surface. y The methods for obtaining and n can refer to existing technologies and are not limited here. It should be noted that formula (1) in the corrosion-resistant titanium alloy impact absorption energy detection method in this example is universal for corrosion-resistant titanium alloys. There is no need to test the corresponding impact absorption energy detection formula for specific grades, which significantly reduces the cost of conducting separate tests for different grades to determine their corresponding parameters.

[0071] Specifically, step S2 includes:

[0072] Step S21: placing the sample 2 on the instrumented pressing device, with the pressing plate 3 supporting the lower side of the second surface of the sample 2, and the sample 2 and the pressing plate 3 being in rigid contact;

[0073] Step S22: using a conical indenter 1 with a vertex angle of θ to press down on the first surface of the sample 2, with the center of the indenter aligned with the center of the first surface of the sample 2;

[0074] Step S23: pressing the depth to a first preset depth;

[0075] Step S24: Unloading after maintaining the first preset time to obtain a first load-depth curve during the pressing process.

[0076] Optionally, the apex angle θ is between 65° and 70°. Preferably, it is 68°. The apex angle θ refers to the angle between two adjacent edges of the conical indenter 1. Through the above-mentioned setting, an indentation can be formed more evenly on the surface of the sample 2. Preferably, the diameter of the pressure plate 3 is greater than the length of the sample 2, and the second surface of the sample 2 is in completely rigid contact with the pressure plate 3. Through the setting of the conical indenter 1, the indentation notch formed on the sample 2 will produce significant stress concentration when subjected to external load, and cracks will be generated from the root of the indentation notch during the second pressing, so as to facilitate more accurate detection of the impact absorption energy of the sample 2.

[0077] Specifically, the first preset depth is 160-240 μm, and the first preset time is 4-6 seconds. Preferably, the first preset depth is 200 μm, and the first preset time is 5 seconds.

[0078] Optionally, the pressing speed of the first pressing test is 0.2-0.4 mm / min, preferably 0.3 mm / min.

[0079] As an example, β is obtained according to the first load-depth curve in step S2. v include:

[0080] The indentation notch depth h is obtained by formula (2): v :

[0081] (2)

[0082] Among them, h max is the maximum indentation depth, α is the indentation coefficient, P max1 is the maximum load when the conical indenter 1 is pressed in, and S is the slope of the first preset interval in the unloading section of the first load-depth curve;

[0083] On this basis, the indentation notch coefficient β is obtained by formula (3): v :

[0084] (3)

[0085] Where l1 is the length of the short side of the first surface, l2 is the length of the long side of the first surface, v is the Poisson's ratio of the tested material, C1 and C2 are intermediate parameters, C1 is obtained by formula (4), and C2 is obtained by formula (5):

[0086] (4)

[0087] (5).

[0088] It should be noted that, because the tested material has a certain elasticity, after unloading, the indentation depth of the conical indenter 1 will rebound to a certain extent. The actual depth of the indentation notch can be obtained more accurately through formula (2), thereby facilitating the acquisition of the indentation notch coefficient β. v It should be noted that the materials tested in this application are all corrosion-resistant titanium alloys, and the Poisson's ratio can generally be set to 0.3. The indenter coefficient is generally related to the shape and vertex angle value of the indenter, and is not specifically limited here. As one of the optional embodiments, the first preset interval refers to 0.6P max1 ~0.95P max1 .

[0089] Specifically, step S3 includes:

[0090] Step S31: placing the sample 2 on two supports 4, with the second surface of the sample 2 facing upward, and the top ends of the two supports 4 making point contact with the first surface of the upper sample 2, with the indentation notch of the sample 2 located at the center of the distance between the two supports 4;

[0091] Step S32: using a spherical indenter 5 with an indenter radius of R to press into the second surface of the sample 2, with the pressing center of the spherical indenter 5 corresponding to the center of the indentation notch;

[0092] Step S33: Press the sample 2 until it breaks, and obtain a second load-depth curve during the pressing process.

[0093] As one optional example, the indenter radius R of the spherical indenter 5 is between 0.4 and 0.6 mm, preferably 0.5 mm. Preferably, the support member 4 is a rod-shaped structure, and the support member 4 is in point contact with the first surface of the sample 2. For example, if the top of the support member 4 is a hemispherical structure, the pressure is more concentrated during the second indentation test, facilitating the fracture of the sample 2. It should be noted that the top of the support member 4 can also be a hemispherical structure or other structure capable of forming point contact with the first surface of the sample 2, which is not limited here.

[0094] As an example, the equivalent indentation fracture energy W is obtained according to the second load-depth curve in step S3. k include:

[0095] According to formula (6), the total equivalent energy U is obtained t :

[0096] (6)

[0097] Among them, U y U is the area of the curve from the load zero point to the load yield point (the point where the load depth curve changes from the straight rising part to the curve rising part),ym is the curve area from the load yield point to the load maximum point, U m is the area of the curve after the maximum load point;

[0098] According to formula (7), the secondary compression equivalent modulus E of the tested material is obtained i :

[0099] (7)

[0100] Among them, L s is the distance between the two support members 4, l1 is the length of the short side of the first surface, l2 is the length of the long side of the first surface, ΔF and Δh are the maximum load values F reached in the second press-in test m Before, the load difference and depth difference corresponding to any two points in the rising section of the second load-depth curve;

[0101] On this basis, the equivalent indentation fracture energy W is obtained by formula (8): k :

[0102] (8)

[0103] Where v is the Poisson's ratio of the material being tested.

[0104] Through the above settings, the equivalent indentation fracture energy of the tested material in the second indentation test can be obtained, thereby obtaining the impact absorption energy of the tested material. y 、U ym 、U m It can be obtained by calculating the second load-depth curve. In this application, the materials tested are all corrosion-resistant titanium alloys, and the Poisson's ratio can generally be set to 0.3. The distance between the two supports 4 refers to the distance between the center points of the two supports 4 in the horizontal direction. When the top of the support is hemispherical, the distance between the two supports 4 is the distance between the centers of the two hemispheres.

[0105] Specifically, in this example, a small rectangular specimen is cut from a titanium alloy raw material and the surface is machined to a specified roughness. A conical indenter (1) is then pressed into one side of the specimen (2) to a specified depth before unloading, introducing an indentation-type notch. The effective notch depth and notch coefficient are calculated based on the first load-depth curve. A three-point bend test is then performed, in which a spherical indenter (5) is pressed into the opposite side of the notch until the specimen fractures. The equivalent indentation fracture energy is calculated based on the second load-depth curve, ultimately calculating the impact absorbed energy of the tested material. In practice, the above method can be tested at different temperatures to determine the impact absorbed energy of the tested material at different temperatures. This setup allows for the impact absorbed energy testing of corrosion-resistant titanium alloys using micro-specimens with a sample volume that is one thousandth or less of that of conventional impact test specimens, significantly accelerating the development of corrosion-resistant titanium alloys and reducing costs. For corrosion-resistant titanium alloy structures in long-term service, micro-destructive sampling can also be performed, providing critical data for in-service safety evaluation and remaining life assessment.

[0106] Example 1

[0107] In this embodiment, the above-mentioned impact absorption energy test is performed using TC4 titanium alloy as an example. The test process includes:

[0108] The TC4 material was processed into 5 pieces of 5.0*1.0*1.0mm after wire cutting and grinding.

[0109] Taking one of the samples as an example, a steel platen is placed on two supports, the supports being support rods 4. The sample is then placed on the platen and a conical indenter with a vertex angle θ of 68° (indenter coefficient α is 0.98) is used to press into a surface with an area of 5.0×1.0mm, with the center of the indenter aligned with the center of the sample. The indentation procedure is set to depth reach, with a target depth of 200μm, an indentation speed of 0.3mm / min, and a hold time of 5s. The test is then started and the first load-depth curve during the indentation process is obtained, see Figure 5 .

[0110] from Figure 5 The maximum penetration depth h is obtained from the first load-depth curve max , Maximum load P when the conical indenter is pressed in max1 and unloading section 0.6P max1 ~0.95P max1 The slope of the indentation is calculated according to formula (2) to obtain the indentation notch depth h v The value is 196.43μm.

[0111] On this basis, the indentation notch coefficient β is calculated according to formulas (3), (4), and (5): v , where l1 is 1.0 mm, l2 is 5.0 mm, v is 0.3, and θ is 68°.

[0112] Remove the compression platen and flip the specimen over and place it on two horizontal support rods. Both support rods have hemispherical tips. The diameter of each hemisphere should be no less than the length of the specimen's shortest edge. The specimen's indentation notch should be centered between the two support rods, with the notch facing downward. A spherical indenter should be pressed into the second surface, opposite the first surface with the indentation notch, until the specimen fractures. A second load-depth curve should be obtained during the indentation process.

[0113] According to formulas (6), (7), and (8), the equivalent indentation fracture energy W is calculated. k .

[0114] The indentation notch coefficient β obtained above is v and equivalent indentation fracture energy W k Substitute into formula (1) to calculate the impact absorption energy of the tested material. The specific calculation results are compared with the results after testing using standard impact specimens in accordance with GB / T229-2020, as shown in Table 1:

[0115] Table 1 Comparison of TC4 test results at room temperature

[0116]

[0117] It can be seen from Table 1 that the mean deviation of the impact absorption energy obtained by the detection method provided in this embodiment and the actual measured value of the impact test conducted according to the standard GB / T229-2020 is 6.98%, indicating that the detection method provided in this embodiment can more accurately detect the impact absorption energy of the corrosion-resistant titanium alloy. However, the sample volume used by the test method provided in this embodiment is about one thousandth of the standard sample, which greatly reduces the consumption of raw materials compared with the standard sample, and can effectively utilize the method of melting small blocks for process screening, thereby achieving improved R&D efficiency and reduced R&D costs.

[0118] Example 2

[0119] In this embodiment, the above-mentioned impact absorption energy test is carried out using Ti70 plate as an example. Ti70 rolled plate is sampled in the transverse and longitudinal directions, and corresponding tests are carried out at different temperatures. At the same time, standard impact specimens are used to carry out tests at different temperatures in accordance with GB / T229-2020. The specific test process can be referred to Example 1. The test results are compared in Tables 2 and 3:

[0120] Table 2 Comparison of transverse specimen test results at a series of temperatures for Ti70 specimens

[0121]

[0122] Table 3 Comparison of test results of longitudinal specimens at a series of temperatures for Ti70 specimens

[0123]

[0124] It can be seen from Tables 2 and 3 that the maximum deviation of the impact absorption energy obtained by the detection method provided in this embodiment and the measured value of the impact test conducted according to the standard GB / T229-2020 at the series test temperatures is -13.33% for the transverse sample, and the maximum deviation of the longitudinal sample is 14.67%, indicating that the detection method provided in this embodiment can more accurately detect the rolling transverse and longitudinal impact absorption energy of the corrosion-resistant titanium alloy. However, the sample volume used by the test method provided in this embodiment is about one thousandth of that of the standard sample, which greatly reduces the consumption of raw materials compared with the standard sample, and can effectively utilize the method of melting small blocks for process screening, thereby achieving improved R&D efficiency and reduced R&D costs.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing, characterized in that: The following steps are involved: Step S1: Sample preparation: Prepare a sample for the press-in test according to a preset size; Step S2: First indentation test: using a conical indenter to indent the first surface of the sample to a first preset depth, maintaining the indenter for a first preset time, and then unloading to obtain a first load-depth curve during the indentation process; Step S3: Second indentation test: Use a spherical indenter to indent the second surface of the sample until the sample breaks, with the first surface and the second surface being opposite surfaces, and obtain a second load-depth curve during the indentation process; Step S4: Calculate the impact absorption energy of the test material according to formula (1): （1） Among them, α I is the impact absorption energy, W k is the equivalent indentation fracture energy, β v is the indentation notch coefficient, E is the elastic modulus of the test material, σ y is the yield strength of the material being tested, n is the strain hardening exponent of the material being tested; β v It can be obtained by the first load-depth curve in step S2, W k It can be obtained through the second load-depth curve in step S3, E, σ y , n can be obtained through the press-in test in step S2 and / or step S3, respectively.

2. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 1, characterized in that: The sample is a micro sample.

3. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 2, characterized in that: The length of the sample is 4-6 mm, the width is 0.8-1.2 mm, and the height is 0.8-1.2 mm.

4. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 1, characterized in that: Step S2 includes: Step S21: placing the sample 2 on the instrumented pressing device, with the pressing plate 3 supporting the lower side of the second surface of the sample 2, and the sample 2 and the pressing plate 3 being in rigid contact; Step S22: using a conical indenter 1 with a vertex angle of θ to press down on the first surface of the sample 2, with the center of the indenter aligned with the center of the first surface of the sample 2; Step S23: pressing the depth to a first preset depth; Step S24: Unloading after maintaining the first preset time to obtain a first load-depth curve during the pressing process.

5. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 4, characterized in that: The first preset depth is 160-240 μm.

6. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 4, characterized in that: The pressing speed of the first pressing test is 0.2~0.4mm / min.

7. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 4, characterized in that: Obtain β according to the first load-depth curve in step S2 v include: The indentation notch depth h is obtained by formula (2): v : （2） Among them, h max is the maximum indentation depth, α is the indentation coefficient, P max1 is the maximum load when the conical indenter 1 is pressed in, and S is the slope of the first preset interval in the unloading section of the first load-depth curve; On this basis, the indentation notch coefficient β is obtained by formula (3): v : （3） Where l1 is the length of the short side of the first surface, l2 is the length of the long side of the first surface, v is the Poisson's ratio of the tested material, C1 and C2 are intermediate parameters, C1 is obtained by formula (4), and C2 is obtained by formula (5): （4） （5）。 8. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 7, characterized in that: The first preset interval is 0.6P max1 ~0.95P max1 .

9. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 1, characterized in that: Step S3 includes: Step S31: placing the sample on two supports, with the second surface of the sample facing upward, and the top ends of the two supports in point contact with the first surface of the upper sample, with the indentation notch of the sample located at the center of the distance between the two supports; Step S32: using a spherical indenter with an indenter radius of R to press into the second surface of the sample, with the indentation center of the spherical indenter corresponding to the center of the indentation notch; Step S33: Press the sample until it breaks, and obtain a second load-depth curve during the pressing process.

10. The method for predicting the impact absorbed energy of corrosion-resistant titanium alloy based on double-sided pressing as claimed in claim 1, characterized in that: Obtain the equivalent indentation fracture energy W according to the second load-depth curve in step S3 k include: According to formula (6), the total equivalent energy U is obtained t : （6） Among them, U y U is the area of the curve from the load zero point to the load yield point (the point where the load depth curve changes from the straight rising part to the curve rising part), ym is the curve area from the load yield point to the load maximum point, U m is the area of the curve after the maximum load point; According to formula (7), the secondary compression equivalent modulus E of the tested material is obtained i : （7） Among them, L s is the distance between the two support members 4, l1 is the length of the short side of the first surface, l2 is the length of the long side of the first surface, ΔF and Δh are the maximum load values F reached in the second press-in test m Before, the load difference and depth difference corresponding to any two points in the rising section of the second load-depth curve; On this basis, the equivalent indentation fracture energy W is obtained by formula (8): k : （8） Where v is the Poisson's ratio of the material being tested.

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