A method for characterizing the deformation characteristics of a TiN alloy

Abstract

The present invention provides a method for characterizing the deformation characteristics of a TiN alloy, relating to the technical field of titanium alloy material processing and preparation. The present invention proposes a deformation damage constitutive equation applicable to TiN alloys. This equation establishes a functional relationship between damage variables and strain, and uses damage variables to characterize the stress-strain relationship during the deformation of the TiN alloy. This method can more realistically reflect the deformation characteristics of the TiN alloy and predict the effective strain range and fracture stress of the TiN alloy within a certain range of deformation conditions. The damage constitutive equation adopted by the present invention is superior to the traditional Zener-Hollomon parameter equation and can more accurately and specifically characterize the deformation characteristics of the TiN alloy.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy material processing and preparation, and in particular to a method for characterizing the deformation characteristics of a TiN alloy. Background Art

[0002] Titanium, known as the "third metal" after steel and aluminum, boasts excellent properties such as high specific strength, excellent corrosion resistance, high-temperature resistance, and non-magnetic properties, making it widely used in the aerospace, automotive, and energy industries. Titanium alloys are typically manufactured through hot forming. Titanium, a chemically active element, reacts with nitrogen in the air during alloy melting and hot forming, forming TiN inclusions. During the use of titanium and titanium alloy components, TiN inclusions can become a source of cracks, shortening component life. Engine discs are considered critical components for aircraft engine failure, and their structural integrity jeopardizes the flight safety of the entire aircraft. Therefore, airworthiness regulations require that "life-limited" parts undergo appropriate damage tolerance assessments to ensure that defects in materials, manufacturing, and use will not lead to potential failures within the approved life of the part.

[0003] Due to the high hardness and melting point of TiN alloy, it is less affected by deformation parameters during the deformation process, and the deformation characteristic data has a certain dispersion. It is impossible to characterize the deformation characteristics of TiN alloy through the traditional functional relationship between deformation activation energy Q and deformation parameters and the Zener-Hollomon parameter equation. Understanding and understanding the characteristics of TiN inclusions in titanium and titanium alloys has become a very urgent problem that needs to be solved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for characterizing the deformation characteristics of TiN alloy, which can accurately predict the effective strain value and fracture strength of TiN alloy within a certain deformation condition range, thereby realizing the characterization of the deformation characteristics of the material.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for characterizing the deformation characteristics of TiN alloy,

[0006] Determine the elastic modulus of TiN alloy;

[0007] Obtain stress-strain values during deformation of TiN alloy samples;

[0008] The damage constitutive equation of TiN alloy during deformation is determined through the one-to-one correspondence between damage variables and strain of TiN alloy.

[0009] Predict the critical strain value of TiN alloy material failure within a certain range of deformation conditions, and bring this strain value into the damage constitutive equation of TiN alloy during deformation to obtain the damage variable when TiN alloy fails within a certain range of deformation conditions;

[0010] According to the predicted critical strain value of material failure, the effective strain range of TiN alloy under certain deformation conditions is determined;

[0011] Based on the obtained damage variables and elastic modulus of TiN alloy at failure within a certain range of deformation conditions and the elastic constitutive equation of damaged material, the fracture stress of TiN alloy within a certain range of deformation conditions is predicted.

[0012] Preferably, the TiN alloy deformation conditions include but are not limited to deformation temperature and strain rate.

[0013] Preferably, the elastic modulus of the TiN alloy is measured according to the requirements of GB / T 22315-2008 "Test method for elastic modulus and Poisson's ratio of metallic materials" by processing the TiN alloy sample into a specimen that meets the test standard and using an environment, equipment and test personnel that meet the test conditions.

[0014] Preferably, the damage constitutive equation of the TiN alloy during deformation, which is determined by the one-to-one correspondence between the damage variable and the strain of the TiN alloy, is as shown in the following formula:

[0015] D=A1+(A1–A2) / (1+(ε / B) n )

[0016] Where D is the damage variable, ε is the strain of TiN alloy during deformation, A1, A2, n and B are the fitting parameters of the damage variable and strain function equation of TiN alloy.

[0017] Preferably, the strain ε of the TiN alloy during deformation is obtained by dividing the instantaneous elongation of the TiN alloy by the instantaneous length.

[0018] Preferably, the method determines the fitting parameters A1, A2, n and B by fitting the damage variable in the damage constitutive equation with the strain value.

[0019] Preferably, the method further obtains the effective strain range during the deformation process of the TiN alloy according to the critical strain value of the material failure within a certain deformation condition range of the TiN alloy, and determines the processing window of the TiN alloy.

[0020] The beneficial effects of the above-mentioned technical solution include: The present invention provides a method for characterizing the deformation characteristics of TiN alloys, proposing a damage constitutive equation for the deformation process of TiN alloys. This method utilizes a damage variable as a medium to establish a functional relationship with strain, and then uses the damage variable to characterize the stress-strain relationship during the deformation of the TiN alloy. This method accurately predicts the effective strain value and fracture strength of the TiN alloy within a certain range of deformation conditions, thereby more realistically describing the deformation characteristics of the TiN alloy. This method overcomes the problem of being unable to characterize the deformation characteristics of TiN alloys using the traditional functional relationship between deformation activation energy Q and deformation parameters and the Zener-Hollomon parameter equation. This method provides a more realistic description of the deformation characteristics of TiN alloys, which is of great significance for promoting the sustainable development of my country's aerospace industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flow chart of a method for characterizing deformation characteristics of a TiN alloy provided in an embodiment of the present invention;

[0022] Figure 2 A corresponding relationship diagram between damage variables and strain of TiN alloy provided in an embodiment of the present invention;

[0023] Figure 3 The damage constitutive equation of the deformation characteristics of the TiN alloy provided by the embodiment of the present invention and the fitting diagram of the test results;

[0024] Figure 4 This is a relationship diagram between the fracture stress and deformation parameters of the TiN alloy provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0026] This embodiment takes a certain TiN alloy sample as an example, and uses the method for characterizing deformation characteristics of the TiN alloy of the present invention to characterize the deformation characteristics of the TiN alloy sample.

[0027] In this embodiment, a method for characterizing the deformation characteristics of a TiN alloy is described. Figure 1 As shown, the following steps are included:

[0028] Step 1, determining the elastic modulus of the TiN alloy;

[0029] In this embodiment, according to the requirements of GB / T 22315-2008 "Test method for elastic modulus and Poisson's ratio of metallic materials", TiN alloy samples were processed into specimens that met the test standards. Under the conditions of environment, equipment and test personnel that met the test conditions, the elastic modulus of the TiN alloy was measured to be E=207 GPa.

[0030] Step 2: Obtaining stress-strain values of the TiN alloy sample during deformation;

[0031] In this example, a TiN alloy sample was subjected to a high-temperature hot compression test on an electronic universal tensile machine equipped with a high-temperature heating furnace. The sample size was a Ø4 mm × 6 mm cylinder. The hot compression temperatures were 910°C, 930°C, 950°C, and 970°C, with a deformation of 20%. The heating rate during the test was 15°C / min, and the sample was held at temperature for 30 minutes to ensure uniform heating. Based on the TiN alloy processing test parameters, the strain range during the deformation of the TiN alloy sample was determined to be 0-0.2.

[0032] Step 3, determining the damage constitutive equation of the TiN alloy during deformation through the one-to-one correspondence between the damage variable and strain of the TiN alloy;

[0033] Affected by the characteristics of TiN alloy itself, the fracture strength of TiN alloy during deformation is insensitive to changes in strain rate and deformation temperature. The deformation characteristic data has a certain dispersion characteristic, and it is impossible to characterize the deformation characteristics of TiN alloy through the traditional functional relationship between deformation activation energy Q and deformation parameters and Zener-Hollomon parameter equation. Under uniaxial stress, the strain constitutive relation of TiN alloy can be derived from non-destructive material, as long as the effective stress after damage to TiN alloy is used to replace the nominal stress in the constitutive relation of non-destructive material. Assuming that the equivalent resistance volume of the undamaged material that actually bears the load due to internal damage of TiN alloy material is V1, the volume of the damaged area is V2, and the total volume (nominal volume) is V. From V=V1+V2, the damage variable D=V2 / V is introduced;

[0034] According to the one-to-one correspondence between the damage variable and strain of the TiN alloy as shown in Figure 2, the damage constitutive equation of the TiN alloy during deformation is determined as follows:

[0035] D=A1+(A1–A2) / (1+(ε / B) n )

[0036] Where D is the damage variable, ε is the strain of the TiN alloy during deformation, A1, A2, n, and B are the fitting parameters of the damage variable and strain function equation of the TiN alloy, which are obtained by fitting the damage variable in the damage constitutive equation with the strain;

[0037] In this embodiment, the damage variables and strain values in the damage constitutive equation are fitted in the originine software to obtain the damage constitutive equation of the TiN alloy sample as shown in the following formula:

[0038] D= 0.9714 -78.844 / (1 + ( ε / 7.5313e -7 ) 0.9024 )

[0039] Step 4: Determine the critical strain value of the TiN alloy when the deformation temperature is within the range of 910°C to 970°C, and substitute this strain value into the damage constitutive equation of the TiN alloy during deformation to obtain the damage variable when the TiN alloy fails when the deformation temperature is within the range of 910°C to 970°C.

[0040] In this embodiment, the critical strain value of material failure during the deformation of the TiN alloy sample is obtained by dividing the instantaneous elongation during the deformation of the TiN alloy by the instantaneous length, ε ≈ 0.01; then, the obtained critical strain value of material failure is substituted into the above damage constitutive equation to obtain D ≈ 0.95 when the TiN alloy sample fails within the deformation temperature range of 910°C-970°C.

[0041] Step 5: Determine the effective strain range of the TiN alloy within the deformation temperature range of 910°C to 970°C based on the determined material failure critical strain value of the TiN alloy within the deformation temperature range of 910°C to 970°C.

[0042] In this embodiment, the obtained material failure critical strain value ε ≈ 0.01 of the TiN alloy is determined, and the effective strain range of the TiN alloy when deformed within the deformation temperature range of 910° C. to 970° C. is determined to be 0-0.01.

[0043] Step 6: Based on the determined damage variable when the TiN alloy fails within the deformation temperature range of 910° C. to 970° C., determine the fracture stress of the TiN alloy during deformation within the deformation temperature range of 910° C. to 970° C.

[0044] In this embodiment, the damage variable D≈0.95 and the elastic modulus E=207 GPa of the TiN alloy in the deformation temperature range of 910°C-970°C are substituted into the elastic constitutive equation of the damaged material to obtain the fracture stress of the TiN alloy in the deformation temperature range of 910°C-970°C to be approximately equal to 400 MPa. The elastic constitutive equation of the damaged material is shown as follows:

[0045] σ = Eε (1− D)

[0046] Where σ is the fracture stress of TiN alloy.

[0047] In this example, the corresponding relationship between the strain values and damage variables obtained from compression tests on a TiN alloy at deformation temperatures of 910°C, 930°C, 950°C, and 970°C is shown in Figure 3, and the damage constitutive equation for the TiN alloy sample fits the equation better than 90%. In this example, if the TiN alloy sample undergoes a high-temperature hot compression test on an electronic universal tensile machine equipped with a high-temperature heating furnace at temperatures of 910°C, 930°C, 950°C, and 970°C, with a heating rate of 15°C / min during the test and a 30-minute hold period after reaching temperature to ensure uniform heating of the test sample, the relationship between the fracture strength of the TiN alloy and the deformation parameters is shown in Figure 4. This figure shows that the fracture strength of the TiN alloy exhibits a certain degree of dispersion within the deformation temperature range of 910°C-970°C, making it impossible to establish a functional relationship between the deformation activation energy Q and the deformation parameters, and thus, it is impossible to construct a traditional Zener-Hollomon parameter constitutive equation.

[0048] Therefore, by comparison, it can be found that the method of the present invention uses the damage variable to establish a functional relationship with strain, and then uses the damage variable to characterize the stress-strain relationship during the deformation process of the TiN alloy. This can accurately predict the effective strain value and fracture strength of the TiN alloy within a certain deformation condition range, thereby more realistically describing the characteristics of the TiN alloy during the deformation process. Comparative test results show that the damage constitutive equation used by the method of the present invention is superior to the traditional Zener-Hollomon parameter equation, and can more accurately and specifically characterize the deformation process of the TiN alloy.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A method for characterizing deformation characteristics of a TiN alloy, characterized by: Determine the elastic modulus of TiN alloy; Obtain stress-strain values during deformation of TiN alloy samples; The damage constitutive equation of TiN alloy during deformation is determined through the one-to-one correspondence between damage variables and strain of TiN alloy. Predict the critical strain value of TiN alloy material failure within a certain deformation range, and bring this strain value into the damage constitutive equation of TiN alloy deformation process to obtain the damage variable when TiN alloy fails within a certain deformation range; According to the predicted critical strain value of material failure, the effective strain range of TiN alloy under certain deformation conditions is determined; According to the obtained damage variables and elastic modulus of TiN alloy at failure within a certain deformation condition range and the elastic constitutive equation of the damaged material, the fracture stress of TiN alloy within a certain deformation condition range is predicted.

2. The method for characterizing deformation characteristics of a TiN alloy according to claim 1, wherein: TiN alloy deformation conditions include but are not limited to deformation temperature and strain rate.

3. The method for characterizing deformation characteristics of a TiN alloy according to claim 1, wherein: The elastic modulus of the TiN alloy is measured according to the requirements of GB / T 22315-2008 "Test method for elastic modulus and Poisson's ratio of metallic materials" by processing the TiN alloy sample into a specimen that meets the test standard and using an environment, equipment and test personnel that meet the test conditions.

4. The method for characterizing deformation characteristics of a TiN alloy according to claim 1, wherein: The damage constitutive equation of the TiN alloy during deformation, determined by the one-to-one correspondence between the damage variable and strain of the TiN alloy, is shown in the following formula: D=A1+(A1-A2) / (1+(ε / B) n ) Where D is the damage variable, ε is the strain of TiN alloy during deformation, A1, A2, n and B are the fitting parameters of the damage variable and strain function equation of TiN alloy.

5. The method for characterizing deformation characteristics of a TiN alloy according to claim 4, wherein: The strain ε of the TiN alloy during deformation is obtained by dividing the instantaneous elongation of the TiN alloy by the instantaneous length.

6. The method for characterizing deformation characteristics of a TiN alloy according to claim 4, wherein: The method determines fitting parameters A1, A2, n and B by fitting the damage variable in the damage constitutive equation with the strain value.

7. A method for characterizing deformation characteristics of a TiN alloy according to any one of claims 2 to 6, characterized in that: The method also obtains the effective strain range of the TiN alloy during deformation according to the critical strain value of material failure within a certain deformation condition range of the TiN alloy, and determines the processing window of the TiN alloy.

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