Single-crystal high-temperature alloy residual stress test optimization method

Abstract

The invention provides an optimization method for testing the residual stress of a single-crystal high-temperature alloy. The optimization method is characterized by comprising the following specific steps: step 1, preparing before testing; the surface of a to-be-detected sample needs to be clean, flat and free of distortion, oxide skin layers and coating coverings, and the to-be-detected sample is loaded on an Euler ring sample table to be located at the diffraction center position; 2, poles are collected, a scanning program is set, the sample is subjected to all-dimensional scanning, the scanning range is the optimized testing range, and the stepping speed is 1 degree; and 3, reading a pole coordinate as an input, and carrying out accurate positioning of a diffraction angle. And 4, calculating the residual stress. Compared with the prior art, the method has the advantages that the test time can be greatly shortened and the test efficiency can be improved under the condition that the test accuracy is ensured.

Description

Technical Field

[0001] The invention relates to the field of residual stress testing of single crystal high temperature alloys, and in particular to a single crystal high temperature alloy residual stress testing optimization method. Background Art

[0002] Single crystal high temperature alloys may generate residual stress during the preparation, processing and use. Excessive residual stress can easily lead to cracks, affect the service performance of parts, and cause safety hazards. The X-ray method is used to test residual stress based on the statistical results of grain lattice strain in the area corresponding to the macroscopic stress. Lattice strain testing is easy to implement for polycrystalline materials, and the technology is relatively mature. Since single crystal high temperature alloys have a single grain and a certain orientation, the number of crystal plane strains that can be collected in each test is limited, and the test time is long and difficult. Therefore, an optimization solution is needed to shorten the test time, improve the test efficiency, and save costs. Summary of the invention

[0003] The purpose of the present invention is to reduce the time of collecting the extreme points of residual stress of single crystal high temperature alloy, improve the testing efficiency and save the cost, and a single crystal high temperature alloy residual stress testing optimization method is provided.

[0004] The present invention provides a single crystal high temperature alloy residual stress test optimization method, which is characterized by comprising the following steps:

[0005] Step 1: Sample preparation

[0006] The size of the sample to be tested is 50mm*30mm*10mm. The surface of the sample should be clean and flat, without distortion, oxide layer, or coating covering, and the roughness Ra should not be greater than 10μm. The oxide layer on the surface of the sample is removed by electrolytic polishing. The electrolytic polishing parameters are: voltage 30V, flow rate level 8, time 20s, and the electrolyte is NaCl solution.

[0007] Step 2: Loading the sample

[0008] After marking the direction of the sample and the point to be tested, use plasticine to fix it in the groove of the sample table, with the surface to be tested facing upwards, and ensure that the point to be tested is flush with the upper surface of the groove; The key points of tooling design are: ensure that the upper end surface of the tooling is horizontal;

[0009] Step 3: Sample alignment

[0010] Turn on the dual-side lasers laser1 and laser2 of the device, adjust the Z-axis height of the standard sample stage so that the intersection of the dual laser beams moves to coincide with the point to be measured, and record the Z-axis coordinate;

[0011] Step 4: Set up the polar graph acquisition program

[0012] Set up the pole figure program and input the standard sample stage axis Z coordinate and scanning range. The scanning range includes the phi value, i.e. the horizontal rotation angle, and the chi value, i.e. the sample tilt angle. The phi value is set to 0-360°, the step length is set to 2°, and the step speed is 0.6s. The angle range of the chi value setting is the optimized test range, the step length is set to 1°, and the step speed is 2min. Record the pole coordinates (chi, phi).

[0013] Step 5: Set up the diffraction peak scanning program

[0014] Read the coordinates of multiple poles (chi, phi) obtained in step 4, locate them respectively and perform precise scanning of the diffraction peaks. The scanning time for each pole is 3 minutes. After the scanning is completed, record the corresponding diffraction angle 2θ respectively.

[0015] Step 6: Calculate residual stress

[0016] The residual stress is calculated by combining the pole coordinates (chi, phi) and the diffraction angle 2θ obtained in steps 4 and 5 with the material constants to obtain the residual stress test results.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The single crystal high temperature alloy residual stress test optimization method described in the present invention greatly shortens the test time and improves the test efficiency while ensuring the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the test optimization solution. DETAILED DESCRIPTION

[0020] The present invention will be further explained below in conjunction with specific implementation plans, but the present invention is not limited thereto. The structures, proportions, and sizes illustrated in the drawings of the specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them. They are not used to limit the conditions under which the present invention can be implemented, so they have no substantive technical significance. Any structural modification, change in proportional relationship, or adjustment of size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0021] Example 1

[0022] Step 1: Sample preparation

[0023] For a single crystal specimen of 20mm*15mm*3mm, the surface oxide layer was removed by electrolytic polishing. The electrolytic polishing parameters were: voltage 30V, flow rate level 8, time 20s, and the electrolyte was NaCl solution.

[0024] Step 2: Load the sample

[0025] The test piece faces upwards, and the width direction is recorded as X, and the length direction is recorded as Y. Use plasticine to fix it in the groove of the sample stage so that the test point on the surface of the test piece is flush with the upper surface of the groove.

[0026] Step 3: Sample alignment

[0027] Turn on the switches of the double-sided lasers laser1 and laser2, adjust the Z axis of the standard sample stage so that the intersection of the dual laser beams moves to coincide with the point to be measured, and record the Z axis coordinate of 0.154 mm.

[0028] Step 4: Set up the polar graph acquisition program

[0029] Set the pole figure program, set the Z-axis coordinate to 0.154 mm, the phi value to 0-360°, the step length to 2°, and the step speed to 0.6 s; the chi value to 1-70°, the step length to 1°, and the step speed to 2 min. After the test, record the pole coordinates (chi, phi). The specific data are shown in Table 1.

[0030] Step 5: Set up the diffraction peak scanning program

[0031] Read the coordinates of the eight poles (chi, phi) obtained in step 4, locate them respectively and perform precise scanning of the diffraction peaks. The scanning time for each pole is 3 minutes. After the scanning is completed, record the corresponding diffraction angles 2θ respectively.

[0032] Step 6: Calculate residual stress

[0033] Combining the pole coordinates (chi, phi) and the diffraction angle 2θ obtained in steps 4 and 5, and combining the material constants to calculate the residual stress, the residual stress test results are -500MPa in the X direction and -497MPa in the Y direction.

[0034] Step 7: Conduct a repeat experiment

[0035] Set the chi value parameter in step 4 to 31°~70°, and then repeat the process from step 4 to step 6. The coordinates of the poles of the repeated test are shown in Table 1. The residual stress X is -490MPa and Y is -495MPa. The pole results of the repeated test are consistent with those of the test test, the residual stress values ​​are consistent, and the pole acquisition time is shortened by 43%.

[0036] Table 1 Summary of pole coordinates

[0037]

[0038] Not all matters of the present invention are known technologies.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A single crystal high temperature alloy residual stress test optimization method, characterized by: The steps are as follows: Step 1: Sample preparation The size of the sample to be tested is 50mm*30mm*10mm. The surface of the sample should be clean and flat, without distortion, oxide layer, or coating covering, and the roughness Ra should not be greater than 10μm. The oxide layer on the surface of the sample is removed by electrolytic polishing. The electrolytic polishing parameters are: voltage 30V, flow rate level 8, time 20s, and the electrolyte is NaCl solution. Step 2: Load the sample After marking the direction of the sample and the point to be tested, use plasticine to fix it in the groove of the sample table, with the surface to be tested facing upwards, and ensure that the point to be tested is flush with the upper surface of the groove; The key points of tooling design are: ensure that the upper end surface of the tooling is horizontal; Step 3: Sample alignment Turn on the dual-side lasers laser1 and laser2 of the device, adjust the Z-axis height of the standard sample stage so that the intersection of the dual laser beams moves to coincide with the point to be measured, and record the Z-axis coordinate; Step 4: Set up the polar graph acquisition program Input the Z coordinate and scanning range of the standard sample stage axis. The scanning range includes the phi value, i.e. the horizontal rotation angle, and the chi value, i.e. the sample tilt angle. The phi value is set to 0-360°, the step length is set to 2°, and the step speed is 0.6s. The angle range set by the chi value is the optimized test range, the step length is set to 1°, and the step speed is 2min. Record the pole coordinates (chi, phi). Step 5: Set up the diffraction peak scanning program Read the coordinates of multiple poles (chi, phi) obtained in step 4, locate them respectively and perform precise scanning of the diffraction peaks. The scanning time for each pole is 3 minutes. After the scanning is completed, record the corresponding diffraction angle 2θ respectively. Step 6: Calculate residual stress The residual stress is calculated by combining the pole coordinates (chi, phi) and the diffraction angle 2θ obtained in steps 4 and 5 with the material constants to obtain the residual stress test results.

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