Method for detecting deep residual stress of workpiece

Abstract

The invention discloses a workpiece deep residual stress detection method, and relates to the technical field of stress measurement, and the method comprises the following steps: S1, preparing a to-be-detected sample; s2, determining the position and depth of a drill hole and the position of an X-ray measuring point; s3, drilling holes in the surface of the sample, wherein the drilling depth is enough to release deep residual stress; s4, performing X-ray diffraction measurement at different depths before and after drilling by using an X-ray measuring instrument, recording a diffraction pattern at each depth measurement point, and analyzing crystal structure information of the diffraction pattern; s5, deformation data before and after drilling is processed, and released stress force is calculated; s6, analyzing crystal structure information obtained by X-ray diffraction measurement, and extracting data related to residual stress; and S7, combining data measured by a drilling method and X-ray diffraction, and performing data analysis. According to the detection method for the deep residual stress of the workpiece adopting the structure, a drilling method and X-ray diffraction measurement are combined, so that the measurement result is more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of stress measurement, and in particular to a method for detecting deep residual stress of a workpiece. Background Art

[0002] Residual stress refers to the self-balanced stress system inside an object when it is not subjected to external forces or after the external forces are unloaded. The existence of residual stress seriously affects the fatigue strength, static strength and corrosion resistance of the workpiece, causing process defects such as deformation and cracking during the manufacturing process, thus affecting the service life of the parts; residual stress is also the main factor affecting the stability of the geometric dimensions of the parts; therefore, it is of great significance to effectively measure the residual stress of the workpiece.

[0003] The measurement methods of residual stress are divided into non-destructive measurement and destructive measurement. Among them, non-destructive measurement includes X-ray method, X-ray diffraction method, neutron diffraction method, scanning electron microscope acoustic microscopy method, electron speckle interferometry method, ultrasonic method and magnetic method; destructive measurement includes drilling method, ring core method, splitting and cutting method, crack flexibility method and peeling curvature radius method. The drilling method is mainly based on the deformation before and after drilling to measure its stress release, but due to the change of the workpiece structure, there is still inaccuracy. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting deep residual stress of a workpiece, a method for detecting deep residual stress of a workpiece, which combines a drilling method with X-ray diffraction measurement to make the measurement result more accurate.

[0005] To achieve the above object, the present invention provides a method for detecting deep residual stress of a workpiece, which is characterized by the following steps:

[0006] S1. Prepare the sample to be tested and ensure that the size and surface quality of the sample meet the measurement requirements of the X-ray detector;

[0007] S2, determine the location and depth of the drill hole, and the location of the X-ray measurement point;

[0008] S3, drilling holes on the sample surface, the drilling depth ensures that it is sufficient to release deep residual stress;

[0009] S4. Use an X-ray measuring instrument to perform X-ray diffraction measurement at different depths before and after drilling. At each depth measurement point, record the diffraction pattern and analyze its crystal structure information;

[0010] S5, processing the deformation data before and after drilling, and calculating the released stress amount;

[0011] S6, analyzing the crystal structure information obtained by X-ray diffraction measurement and extracting data related to residual stress;

[0012] S7. Combine the data from the drilling method and X-ray diffraction measurement to perform data analysis.

[0013] Preferably, in S2, the method for determining the position and depth of the drilling hole is as follows:

[0014] (1) Cut a slope along the depth direction of the sample to be tested;

[0015] (2) Drilling stress measurement holes along the normal direction of the inclined surface;

[0016] (3) The stress measurement holes are arranged in a straight line or in a broken line on the inclined surface;

[0017] (4) The diameter of the stress measurement hole is d, the depth of the stress measurement hole is 0.6d, and the distance between adjacent stress measurement holes in the direction parallel to the inclined surface is at least 4d.

[0018] Preferably, in S2, the method for determining the X-ray measurement points is as follows: the X-ray measurement points include two groups, the positions of the first group of X-ray measurement points overlap with the drilling positions, and the measurement depth is the same as the drilling depth; the positions of the second group of X-ray measurement points are parallel to the drilling positions and are separated from the drilling positions by more than 5d.

[0019] Preferably, in S5, a laser interferometer stress meter is used to obtain deformation data of the stress measurement hole, and the amount of released stress is calculated.

[0020] Therefore, the present invention adopts a method for detecting deep residual stress of a workpiece using the above steps, detects the deep residual stress of the workpiece by a drilling method, measures the crystal structure information before and after drilling by X-rays and compares them, and assists in verifying the results of the drilling method detection, thereby achieving more accurate and efficient residual stress measurement.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a flow chart of an embodiment of a method for detecting deep residual stress of a workpiece according to the present invention;

[0023] Figure 2 A schematic diagram of the single-row drilling positions and X-ray measurement point distribution of an embodiment of the present invention;

[0024] Figure 3 Schematic diagram of double-row drilling positions and X-ray measurement point distribution according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0026] Example

[0027] like Figure 1 As shown, a method for detecting deep residual stress of a workpiece is characterized by the following steps:

[0028] S1. Prepare the sample to be tested and ensure that the size and surface quality of the sample meet the measurement requirements of the X-ray detector;

[0029] S2. The method for determining the location and depth of the drilling hole is as follows:

[0030] (1) Cut a slope along the depth direction of the sample to be tested;

[0031] (2) Drilling stress measurement holes along the normal direction of the inclined surface;

[0032] (3) The stress measurement holes are arranged in a straight line or in a broken line on the inclined surface;

[0033] (4) The diameter of the stress measurement hole is d, the depth of the stress measurement hole is 0.6d, and the distance between adjacent stress measurement holes in the direction parallel to the inclined surface is at least 4d. Try to avoid mutual interference between drilling positions.

[0034] Determine the position of the X-ray measurement points: The X-ray measurement points include two groups. The position of the first group of X-ray measurement points overlaps with the drilling position, and the measurement depth is the same as the drilling depth. The position of the second group of X-ray measurement points is parallel to the drilling position and is separated from the drilling position by more than 5 days. By performing X-ray measurement on non-drilling positions, it can be used as a reference for the measurement results to consider the impact of deformation on stress release at a certain distance.

[0035] The drilling positions can be single row or double row. Figure 2 As shown, the double row type Figure 3 The hollow circles in the figure represent the drilling positions, and the solid points represent the X-ray measurement points.

[0036] S3, drilling holes on the sample surface, the drilling depth ensures that it is sufficient to release deep residual stress;

[0037] S4. Use an X-ray measuring instrument to perform X-ray diffraction measurement at different depths before and after drilling. At each depth measurement point, record the diffraction pattern and analyze its crystal structure information;

[0038] S5. Using a laser interferometer stress meter to obtain deformation data of the stress measurement hole, processing the deformation data before and after drilling, and calculating the released stress amount;

[0039] S6, analyzing the crystal structure information obtained by X-ray diffraction measurement and extracting data related to residual stress;

[0040] S7. Combine the data from the drilling method and X-ray diffraction measurement to perform data analysis.

[0041] Therefore, the present invention adopts a method for detecting deep residual stress of a workpiece using the above steps, detects the deep residual stress of the workpiece by a drilling method, measures the crystal structure information before and after drilling by X-rays and compares them, and assists in verifying the results of the drilling method detection, thereby achieving more accurate and efficient residual stress measurement.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for detecting deep residual stress of a workpiece, characterized in that: Here are the steps: S1. Prepare the sample to be tested and ensure that the size and surface quality of the sample meet the measurement requirements of the X-ray detector; S2, determine the location and depth of the drill hole, and the location of the X-ray measurement point; S3, drilling holes on the sample surface, the drilling depth ensures that it is sufficient to release deep residual stress; S4. Use an X-ray measuring instrument to perform X-ray diffraction measurement at different depths before and after drilling. At each depth measurement point, record the diffraction pattern and analyze its crystal structure information; S5, processing the deformation data before and after drilling, and calculating the released stress amount; S6, analyzing the crystal structure information obtained by X-ray diffraction measurement and extracting data related to residual stress; S7. Combine the data from the drilling method and X-ray diffraction measurement to perform data analysis.

2. The method for detecting deep residual stress of a workpiece according to claim 1, characterized in that: In S2, the method for determining the location and depth of the drilling hole is as follows: (1) Cut a slope along the depth direction of the sample to be tested; (2) Drilling stress measurement holes along the normal direction of the inclined surface; (3) The stress measurement holes are arranged in a straight line or in a broken line on the inclined surface; (4) The diameter of the stress measurement hole is d, the depth of the stress measurement hole is 0.6d, and the distance between adjacent stress measurement holes in the direction parallel to the inclined surface is at least 4d.

3. The method for detecting deep residual stress of a workpiece according to claim 2, characterized in that: In S2, the method for determining the X-ray measurement points is as follows: the X-ray measurement points include two groups, the positions of the first group of X-ray measurement points overlap with the drilling positions, and the measurement depth is the same as the drilling depth, and the positions of the second group of X-ray measurement points are parallel to the drilling positions and are separated from the drilling positions by more than 5d.

4. The method for detecting deep residual stress of a workpiece according to claim 2, characterized in that: In S5, a laser interferometer stress meter is used to obtain deformation data of the stress measurement hole and calculate the amount of released stress.

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