A method for reducing residual stress of rare earth heat-treated steel

Abstract

The present invention relates to the technical field of residual stress treatment, and in particular to a method for reducing residual stress of rare earth heat-treated steel, comprising: controlling the cooling rate in the process of rare earth heat-treated steel to obtain initial steel; tempering and cooling the initial steel to obtain pretreated steel; performing stress audio intensity detection on the pretreated steel, determining residual stress distribution parameters according to the audio intensity detection result, so as to determine the stress treatment category of the pretreated steel; determining a way to reduce residual stress in the pretreated steel according to the stress treatment category of the pretreated steel, and adjusting a criterion for determining the stress treatment category of the pretreated steel according to the number of pretreated steels corresponding to different stress treatment categories; the present invention determines stress distribution in steel by a non-destructive method and adaptively selects a stress treatment strategy, thereby reducing the risk of material damage, while improving production efficiency and product quality, and ensuring the performance and reliability of steel in various application scenarios.

Description

Technical Field

[0001] The invention relates to the technical field of residual stress treatment, in particular to a method for reducing residual stress of rare earth heat-treated steel. Background Art

[0002] Steels that have undergone rare earth heat treatment are widely used in multiple industrial fields. Their main uses include improving corrosion resistance, making them suitable for chemical equipment and marine engineering; enhancing wear resistance for the manufacture of mechanical parts and cutting tools; improving processing performance, making them suitable for processing workpieces with complex shapes and high precision requirements; improving strength and high temperature resistance for use in oil drilling and power generation equipment; and improving welding performance, reducing the risk of cracks and deformation during welding, and meeting the specific needs of structural components.

[0003] Chinese Patent Publication No.: CN111004910B discloses an experimental system for reducing residual stress of plate and strip materials, including a heat preservation furnace, a forward traction device and a reverse traction device are arranged outside the heat preservation furnace, and at least two furnace rollers are arranged inside the heat preservation furnace; the forward traction device is used to connect one end of the plate and strip material, and the reverse traction device is used to connect the other end of the plate and strip material, so that the plate and strip material can move back and forth under the drive of the forward traction device and the reverse traction device; the furnace rollers are used to make the plate and strip material S-shaped winding, at least one of which has a guide roller surface for contacting the upper surface of the plate and strip material, and at least one has a guide roller surface for contacting the lower surface of the plate and strip material, and the plate and strip material is tensioned under the action of the forward traction device and the reverse traction device.

[0004] However, the prior art still has the following problems: in actual situations, the uneven distribution is not taken into account when residual stress is treated on rare earth heat-treated steel, and the treated steel cannot meet the performance requirements of rare earth heat-treated steel in actual applications. Summary of the invention

[0005] To this end, the present invention provides a method for reducing residual stress of rare earth heat-treated steel, so as to overcome the problem in the prior art that the uneven distribution is not taken into account when residual stress treatment is performed on rare earth heat-treated steel, and the treated steel cannot meet the performance requirements of rare earth heat-treated steel in practical applications.

[0006] To achieve the above object, the present invention provides a method for reducing residual stress of rare earth heat-treated steel, comprising:

[0007] Controlling the cooling rate during rare earth heat treatment of steel to obtain initial steel;

[0008] The initial steel is heated, the tempering temperature is maintained until the preset tempering time, and the tempering cooling rate is used to cool the initial steel to room temperature to obtain a pretreated steel;

[0009] Performing stress audio intensity testing on the pretreated steel, and determining residual stress distribution parameters according to the audio intensity testing results to determine the stress treatment category of the pretreated steel;

[0010] Determining a method for reducing residual stress in the pretreated steel according to the stress treatment category of the pretreated steel includes:

[0011] Performing a flatness test on the surface of the pretreated steel, determining a grinding method for each test area according to the flatness test result, and performing grinding to obtain a final steel;

[0012] Or, the pretreated steel is subjected to ultrasonic vibration treatment to obtain a preliminarily stress-reduced steel, the preliminarily stress-reduced steel is subjected to X-ray detection to obtain a diffraction spectrum to draw a diffraction peak line graph, and the residual stress treatment remaining parameter is determined according to the diffraction peak line graph to determine whether to perform surface grinding on the preliminarily stress-reduced steel to obtain the final steel;

[0013] The criteria for determining the stress treatment category of the pretreated steel are adjusted according to the number of pretreated steels corresponding to different stress treatment categories.

[0014] Further, the pretreated steel is subjected to stress audio intensity testing, including:

[0015] Dividing the pretreated steel into a plurality of detection areas of the same shape, and determining the center of each detection area;

[0016] Using a knocking tool to knock on the center of each detection area several times, and recording the average value of the knocking audio intensity;

[0017] The knocking force and the knocking speed of knocking on the center of each detection area are the same.

[0018] Furthermore, the residual stress distribution parameter is determined according to formula (1):

[0019] ,

[0020] In formula (1), Fs is the residual stress distribution parameter, n is the total number of detection areas, Bi is the average audio intensity of the i-th detection area, B0 is the average audio intensity of the pretreated steel, and i is an integer greater than 0.

[0021] Further, determining the stress treatment category of the pretreated steel material according to the residual stress distribution parameter;

[0022] If the residual stress distribution parameter is less than the standard residual stress distribution parameter, the stress treatment category of the pretreated steel is a direct stress treatment category;

[0023] If the residual stress distribution parameter is greater than or equal to the standard residual stress distribution parameter, the stress treatment category of the pretreated steel is an indirect stress treatment category.

[0024] Furthermore, according to the stress treatment category of the pretreated steel, a method for reducing the residual stress in the corresponding pretreated steel is determined, including:

[0025] If the stress treatment category of the pre-treated steel is a direct stress treatment category, the residual stress is reduced by performing a flatness test on the surface of the pre-treated steel, determining a grinding method for each test area according to the flatness test result, and performing grinding to obtain the final steel;

[0026] If the stress treatment category of the pretreated steel is an indirect stress treatment category, the method for reducing the residual stress is to perform ultrasonic vibration treatment on the pretreated steel to obtain a steel with preliminary reduced stress, perform X-ray detection on the steel with preliminary reduced stress to obtain a diffraction spectrum to draw a diffraction peak line graph, and determine the residual stress treatment remaining parameters based on the diffraction peak line graph to determine whether to perform surface grinding on the steel with preliminary reduced stress to obtain the final steel.

[0027] Furthermore, the surface of the pretreated steel is tested for flatness, including:

[0028] Acquire an image of the pre-treated steel surface and perform grayscale processing to obtain a flat analysis image;

[0029] Determine the corresponding position of each of the detection areas in the flattened analysis image;

[0030] The average grayscale value of each detection area is obtained and recorded as the detection result of the flatness detection.

[0031] Furthermore, the grinding method of each detection area is determined according to the flatness detection result, including:

[0032] If the average gray value of the detection area is greater than the standard gray value, the grinding method is to grind the raised area and then refine the surface;

[0033] If the average gray value of the detection area is less than or equal to the standard gray value, the grinding method is to refine and grind the corresponding surface of the detection area.

[0034] Furthermore, the residual stress treatment remaining parameter is determined according to formula (2):

[0035] ,

[0036] In formula (2), Fn is the residual stress treatment parameter, m is the total number of diffraction peaks, Hj is the jth diffraction peak, H0 is the average value of the diffraction peaks, and j is an integer greater than 0.

[0037] Further, determining whether to perform surface grinding on the initially stress-reduced steel material according to the residual stress treatment remaining parameters includes:

[0038] If the residual stress treatment leftover parameter is greater than or equal to the standard treatment leftover parameter, no surface grinding is performed on the initially stress-reduced steel;

[0039] If the residual stress treatment leftover parameter is less than the standard treatment leftover parameter, the initially stress-reduced steel is subjected to surface grinding.

[0040] Further, the criteria for determining whether to adjust the stress treatment category is determined according to the number of pre-treated steel materials corresponding to different stress treatment categories, including:

[0041] If several consecutive pre-treated steels are of the direct stress treatment category, the standard residual stress distribution parameters are reduced;

[0042] If several consecutive pre-treated steels are of the indirect stress treatment type, the standard residual stress distribution parameters are increased.

[0043] Compared with the prior art, the beneficial effect of the present invention is that by controlling the cooling rate, audio intensity detection, flatness detection and ultrasonic vibration treatment and other steps, the residual stress in the steel can be effectively identified and reduced, and the residual stress distribution of the steel can be non-destructively evaluated, providing data support for subsequent stress treatment methods, ensuring that the treated steel meets the performance requirements in practical applications. In addition, the present invention simplifies the treatment process, avoids the material damage that may be caused by traditional destructive testing, while improving production efficiency and the quality of steel, providing a more reliable technical guarantee for the application of rare earth heat-treated steel. By adjusting the judgment criteria for stress treatment categories, the present invention further improves the adaptability and flexibility of stress treatment, ensuring that steels with different stress distribution characteristics can be properly treated, thereby improving the performance and reliability of the final product.

[0044] Furthermore, the sound and vibration characteristics of the steel when knocked can be obtained through the tapping method, so that the residual stress distribution of the steel can be determined. This simple and fast non-destructive testing method is suitable for rapid on-site evaluation. Although it cannot provide accurate values, it can identify possible problems or stress concentration areas of the steel, avoiding material damage that may be caused by traditional destructive testing. Therefore, the residual stress distribution parameters determined according to the audio intensity characterize the distribution of residual stress in the steel, and further provide data support for the subsequent selection of residual stress processing methods, which facilitates the adaptive selection of processing methods for steels with different stress distributions in the subsequent processing process, while ensuring the residual stress treatment effect and simplifying the processing process.

[0045] In the present invention, the method for reducing residual stress is determined according to the stress treatment category of the pretreated steel, and different subsequent treatment methods are adopted for different types of pretreated steel. The stress distribution of the pretreated steel with low residual stress distribution parameters meets the requirements, and the final prepared steel is obtained by grinding the steel surface to meet the performance requirements of rare earth treated steel in practical applications.

[0046] In the present invention, the stress distribution of the pretreated steel with high residual stress distribution parameters does not meet the requirements, resulting in the steel directly prepared in the end not meeting the performance requirements of rare earth treated steel in practical applications. Therefore, the residual stress is processed again by ultrasonic vibration to provide production guarantee for the quality of the final steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A flow chart of a method for reducing residual stress of rare earth heat-treated steel according to an embodiment of the present invention;

[0048] Figure 2 A logic diagram for determining a stress treatment category for pre-treated steel for an embodiment of the present invention;

[0049] Figure 3 A logic diagram of determining the grinding method of each detection area according to the flatness detection result in an embodiment of the present invention;

[0050] Figure 4 This is a logic diagram for determining whether to perform surface grinding on a steel material with initially reduced stress according to the parameters left over from residual stress treatment according to an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0052] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0053] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0054] See also Figure 1As shown, it is a flow chart of a method for reducing residual stress of rare earth heat-treated steel according to an embodiment of the present invention; the present invention provides a method for reducing residual stress of rare earth heat-treated steel, comprising:

[0055] Step S1, controlling the cooling rate during rare earth heat treatment of steel to obtain initial steel;

[0056] Step S2, heating the initial steel, maintaining the tempering temperature to a preset tempering time, and cooling the steel to room temperature using a tempering cooling rate to obtain a pretreated steel;

[0057] Step S3, performing stress audio intensity detection on the pretreated steel, and determining residual stress distribution parameters according to the audio intensity detection result to determine the stress treatment category of the pretreated steel;

[0058] Step S4, determining a method for reducing residual stress in the pretreated steel according to the stress treatment category of the pretreated steel, including:

[0059] Performing a flatness test on the surface of the pretreated steel, determining a grinding method for each test area according to the flatness test result, and performing grinding to obtain a final steel;

[0060] Or, the pretreated steel is subjected to ultrasonic vibration treatment to obtain a preliminarily stress-reduced steel, the preliminarily stress-reduced steel is subjected to X-ray detection to obtain a diffraction spectrum to draw a diffraction peak line graph, and the residual stress treatment remaining parameter is determined according to the diffraction peak line graph to determine whether to perform surface grinding on the preliminarily stress-reduced steel to obtain the final steel;

[0061] Step S5, adjusting and determining the criteria for determining the stress treatment category of the pretreated steel according to the number of pretreated steels corresponding to different stress treatment categories.

[0062] In the actual production process, too fast cooling rate may lead to higher residual stress. By controlling the cooling rate of the steel, the residual stress inside the steel obtained after production can be effectively reduced.

[0063] In practice, in step S2, tempering the steel is a basic operation for treating the residual stress of the steel. This is a prior art and will not be described in detail.

[0064] By controlling the cooling rate, audio intensity detection, flatness detection, and ultrasonic vibration treatment, the residual stress in the steel can be effectively identified and reduced, and the residual stress distribution of the steel can be non-destructively evaluated to provide data support for subsequent stress treatment methods, thereby ensuring that the treated steel meets the performance requirements in practical applications. In addition, the present invention simplifies the treatment process, avoids material damage that may be caused by traditional destructive testing, and at the same time improves production efficiency and the quality of steel, providing a more reliable technical guarantee for the application of rare earth heat-treated steel. By adjusting the judgment criteria for stress treatment categories, the present invention further improves the adaptability and flexibility of stress treatment, ensuring that steels with different stress distribution characteristics can be properly treated, thereby improving the performance and reliability of the final product.

[0065] See also Figure 2 As shown, it is a logic diagram for determining the stress treatment category of pre-treated steel according to an embodiment of the present invention, and performing stress audio intensity detection on the pre-treated steel, including:

[0066] Dividing the pretreated steel into a plurality of detection areas of the same shape, and determining the center of each detection area;

[0067] Using a knocking tool to knock on the center of each detection area several times, and recording the average value of the knocking audio intensity;

[0068] The knocking force and the knocking speed of knocking on the center of each detection area are the same.

[0069] It can be understood that the tapping method is a simple method for preliminarily estimating residual stress in materials or structures. It is especially suitable for large structures or situations where traditional measurement methods cannot be used. The existence and approximate distribution of residual stress can be inferred by the different sound frequencies or sound characteristics generated by the material under different stresses.

[0070] In practice, a suitable striking tool is selected to strike the steel, usually a tap hammer or other tool that can produce a clear sound is used to ensure that the force and frequency of the strikes are consistent in order to compare the responses at different positions. The audio intensity of the strikes in each detection area is recorded by an audio sensor. The residual stress inside the material will cause different sound characteristics at different positions. Generally, areas with greater residual stress will produce stronger sound responses different from normal states.

[0071] The audio sensor can be any one of the existing sensors. This is existing technology and is not specifically limited. The number of detection areas is not less than 20, and the shapes of the detection areas are the same. The number of tapping on a single detection area is preferably 5 times.

[0072] Specifically, the residual stress distribution parameter is determined according to formula (1):

[0073] ,

[0074] In formula (1), Fs is the residual stress distribution parameter, n is the total number of detection areas, Bi is the average audio intensity of the i-th detection area, B0 is the average audio intensity of the pretreated steel, and i is an integer greater than 0.

[0075] Specifically, determining the stress treatment category of the pretreated steel material according to the residual stress distribution parameter;

[0076] If the residual stress distribution parameter is less than the standard residual stress distribution parameter, the stress treatment category of the pretreated steel is a direct stress treatment category;

[0077] If the residual stress distribution parameter is greater than or equal to the standard residual stress distribution parameter, the stress treatment category of the pretreated steel is an indirect stress treatment category.

[0078] In practice, the standard residual stress distribution parameters are selected in the interval [0.3, 0.4].

[0079] In the present invention, the sound and vibration characteristics of the steel when knocked are obtained by the knocking method, so that the residual stress distribution of the steel can be determined. This simple and fast non-destructive testing method is suitable for rapid on-site evaluation. Although it cannot provide accurate values, it can identify possible problems or stress concentration areas of the steel, avoiding material damage that may be caused by traditional destructive testing. Therefore, the residual stress distribution parameters determined according to the audio intensity characterize the distribution of the residual stress of the steel, and further provide data support for the subsequent selection of the method for processing the residual stress, so that steels with different stress distributions can adaptively select the processing method in the subsequent processing process, while ensuring the residual stress treatment effect, simplifying the processing process.

[0080] Specifically, the method for reducing the residual stress in the corresponding pretreated steel is determined according to the stress treatment category of the pretreated steel, including:

[0081] If the stress treatment category of the pre-treated steel is a direct stress treatment category, the residual stress is reduced by performing a flatness test on the surface of the pre-treated steel, determining a grinding method for each test area according to the flatness test result, and performing grinding to obtain the final steel;

[0082] If the stress treatment category of the pretreated steel is an indirect stress treatment category, the method for reducing the residual stress is to perform ultrasonic vibration treatment on the pretreated steel to obtain a steel with preliminary reduced stress, perform X-ray detection on the steel with preliminary reduced stress to obtain a diffraction spectrum to draw a diffraction peak line graph, and determine the residual stress treatment remaining parameters based on the diffraction peak line graph to determine whether to perform surface grinding on the steel with preliminary reduced stress to obtain the final steel.

[0083] See also Figure 3 As shown, it is a logic diagram of determining the grinding method of each detection area according to the flatness detection result of an embodiment of the present invention, and performing flatness detection on the surface of the pre-treated steel material, including:

[0084] Acquire an image of the pre-treated steel surface and perform grayscale processing to obtain a flat analysis image;

[0085] Determine the corresponding position of each of the detection areas in the flattened analysis image;

[0086] The average grayscale value of each detection area is obtained and recorded as the detection result of the flatness detection.

[0087] In implementation, the grayscale value ranges from 0 to 255, with white being 255 and black being 0. It can be understood that when a light source is irradiated from one direction, the raised portion reflects more light because it faces the light source at a larger angle, making the raised portion appear brighter, that is, the grayscale value is higher. In contrast, the recessed portion faces the light source at a smaller angle and receives less direct light, thus appearing as a lower grayscale value.

[0088] Specifically, the grinding method of each detection area is determined according to the flatness detection result, including:

[0089] If the average gray value of the detection area is greater than the standard gray value, the grinding method is to grind the raised area and then refine the surface;

[0090] If the average gray value of the detection area is less than or equal to the standard gray value, the grinding method is to refine and grind the corresponding surface of the detection area.

[0091] In implementation, the standard gray value is the overall average gray value of the smoothed analysis image.

[0092] The grinding degree of the raised area can be determined by obtaining a flat analysis image in real time. The grinding tool used for fine grinding is the same as that used for grinding the raised area. This is a prior art and is not specifically limited.

[0093] Grinding the surface can reduce the residual stress in the material or structure. By removing the material in the surface layer, the residual stress in the surface layer can be reduced. Residual stress is usually concentrated in the surface layer of the material, especially in the cooling stress or plastic deformation area generated during the processing. In addition, by grinding, the surface roughness can be reduced, thereby reducing the possibility of surface microcracks and stress concentration. Rough surfaces are prone to accumulate residual stress, and these stresses can lead to the formation of microcracks and fatigue cracks in the material.

[0094] In the present invention, the method for reducing residual stress is determined according to the stress treatment category of the pretreated steel, and different subsequent treatment methods are adopted for different types of pretreated steel. The stress distribution of the pretreated steel with low residual stress distribution parameters meets the requirements, and the final prepared steel is obtained by grinding the steel surface to meet the performance requirements of rare earth treated steel in practical applications.

[0095] See also Figure 4 As shown, it is a logic diagram of determining whether to perform surface grinding on the initially stress-reduced steel material according to the residual stress treatment legacy parameters according to an embodiment of the present invention. The residual stress treatment legacy parameters are determined according to formula (2):

[0096] ,

[0097] In formula (2), Fn is the residual stress treatment parameter, m is the total number of diffraction peaks, Hj is the jth diffraction peak, H0 is the average value of the diffraction peaks, and j is an integer greater than 0.

[0098] In practice, ultrasonic vibration is used to locally treat the material surface or welding area to eliminate local residual stress. High-frequency vibration is generated by an ultrasonic generator and transmitted to the workpiece surface or welding area to reduce stress concentration and residual stress through vibration.

[0099] The equipment for reducing the residual stress of steel by ultrasonic vibration treatment is preferably Ultrasonic Stress Relief Equipment. The equipment can use the high-frequency vibration of ultrasound to change the internal stress distribution of the material, thereby reducing or eliminating the residual stress in the steel; the ultrasonic vibration generated by the device can penetrate the surface of the material and go deep into the interior, acting on the grain boundaries and dislocations of the material, thereby causing tiny displacements and plastic deformations, which help to release or reduce the residual stress in the local area. Continuous ultrasonic action can also slow down or eliminate the residual stress in the material after proper treatment. This treatment helps to improve the mechanical properties and corrosion resistance of the material.

[0100] Ultrasonic vibration processing equipment can usually adjust the frequency to suit different types and thicknesses of steel, and the frequency is generally between 20 kHz and 100 kHz.

[0101] The method of determining residual stress in steel by X-ray is mainly based on X-ray diffraction technology. The specific steps and principles are as follows:

[0102] Select diffraction peak: First, scan the sample within a certain angle range and select a diffraction peak with high intensity, no diffusion, and high diffraction surface index as the research object;

[0103] Measuring the diffraction angle: according to the requirements of residual stress measurement, set different ψ angles (such as 0°, 15°, 30°, 45°), and measure the diffraction angle 2θ of the diffraction peak at different ψ angles;

[0104] Determine the peak position: In macro stress measurement, it is extremely important to accurately determine the position of the diffraction peak. Commonly used peak determination methods include half-width method, 1 / 8 height method, peak top method, tangent method, etc., and the three-point parabola fitting peak determination method is preferred;

[0105] Data fitting: Use software (such as MDI Jade) to fit the measured data, determine the peak value, and draw a peak line graph.

[0106] Specifically, determining whether to perform surface grinding on the initially stress-reduced steel material according to the residual stress treatment remaining parameters includes:

[0107] If the residual stress treatment leftover parameter is greater than or equal to the standard treatment leftover parameter, no surface grinding is performed on the initially stress-reduced steel;

[0108] If the residual stress treatment leftover parameter is less than the standard treatment leftover parameter, the initially stress-reduced steel is subjected to surface grinding.

[0109] In practice, the standard treatment carryover parameters are selected in the interval [0.15, 0.25]; the method of surface grinding of the initially stress-reduced steel is the same as the method of fine grinding of the surface corresponding to the inspection area of ​​the pre-treated steel.

[0110] When the residual stress treatment legacy parameters are greater than or equal to the standard treatment legacy parameters, according to the diffraction peak line graph, the steel area corresponding to the peak value greater than the average peak value is subjected to secondary ultrasonic vibration treatment until the residual stress treatment legacy parameters are less than the standard treatment legacy parameters and then the steel surface is ground.

[0111] In the present invention, the stress distribution of the pretreated steel with high residual stress distribution parameters does not meet the requirements, resulting in the steel directly prepared in the end not meeting the performance requirements of rare earth treated steel in practical applications. Therefore, the residual stress is processed again by ultrasonic vibration to provide production guarantee for the quality of the final steel.

[0112] Specifically, the criteria for adjusting the stress treatment category are determined based on the number of pre-treated steel materials corresponding to different stress treatment categories, including:

[0113] If several consecutive pre-treated steels are of the direct stress treatment category, the standard residual stress distribution parameters are reduced;

[0114] If several consecutive pre-treated steels are of the indirect stress treatment type, the standard residual stress distribution parameters are increased.

[0115] In implementation, the number of consecutive pre-treated steels that are in the indirect stress treatment category or the number of consecutive pre-treated steels that are in the direct stress treatment category is preferably 5, and the stress treatment category of the pre-treated steel needs to be re-determined after adjusting the judgment criteria;

[0116] The standard residual stress distribution parameter is reduced to 0.9 times of the original value when it is reduced; the standard residual stress distribution parameter is increased to 0.9 times of the original value when it is increased, and does not exceed the determined range of the standard residual stress distribution parameter.

[0117] If the method of reducing residual stress of rare earth heat-treated steel of the present invention is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0118] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for reducing residual stress in rare earth heat-treated steel, characterized in that: include: Controlling the cooling rate during rare earth heat treatment of steel to obtain initial steel; The initial steel is heated, the tempering temperature is maintained until the preset tempering time, and the tempering cooling rate is used to cool the initial steel to room temperature to obtain a pretreated steel; Performing stress audio intensity testing on the pretreated steel, and determining residual stress distribution parameters according to the audio intensity testing results to determine the stress treatment category of the pretreated steel; If the residual stress distribution parameter is less than the standard residual stress distribution parameter, the stress treatment category of the pretreated steel is a direct stress treatment category; If the residual stress distribution parameter is greater than or equal to the standard residual stress distribution parameter, the stress treatment category of the pretreated steel is an indirect stress treatment category; Determining a method for reducing residual stress in the pretreated steel according to the stress treatment category of the pretreated steel includes: If the stress treatment category of the pre-treated steel is a direct stress treatment category, a flatness test is performed on the surface of the pre-treated steel, and a grinding method for each detection area is determined according to the flatness test result and the final steel is obtained by grinding. If the stress treatment category of the pretreated steel is an indirect stress treatment category, the pretreated steel is subjected to ultrasonic vibration treatment to obtain a preliminarily stress-reduced steel, X-ray detection is performed on the preliminarily stress-reduced steel to obtain a diffraction spectrum to draw a diffraction peak line graph, and residual stress treatment remaining parameters are determined according to the diffraction peak line graph to determine whether to perform surface grinding on the preliminarily stress-reduced steel to obtain a final steel; Adjusting and determining the criteria for determining the stress treatment category of the pretreated steel according to the number of pretreated steels corresponding to different stress treatment categories; The residual stress distribution parameters are determined according to formula (1): ， In formula (1), Fs is the residual stress distribution parameter, n is the total number of detection areas, Bi is the average audio intensity of the i-th detection area, B0 is the average audio intensity of the pretreated steel, and i is an integer greater than 0; The residual stress treatment parameters are determined according to formula (2): ， In formula (2), Fn is the residual stress treatment parameter, m is the total number of diffraction peaks, Hj is the jth diffraction peak, H0 is the average value of the diffraction peaks, and j is an integer greater than 0.

2. The method for reducing residual stress of rare earth heat-treated steel according to claim 1, characterized in that: The pre-treated steel is subjected to stress audio strength testing, including: Dividing the pretreated steel into a plurality of detection areas of the same shape, and determining the center of each detection area; Using a knocking tool to knock on the center of each detection area several times, and recording the average value of the knocking audio intensity; The knocking force and the knocking speed of knocking on the center of each detection area are the same.

3. The method for reducing residual stress of rare earth heat-treated steel according to claim 1, characterized in that: The surface of the pre-treated steel material is tested for flatness, including: Acquire the image of the pre-treated steel surface and perform grayscale processing to obtain a flat analysis image; Determine the corresponding position of each of the detection areas in the flattened analysis image; The average grayscale value of each detection area is obtained and recorded as the detection result of the flatness detection.

4. The method for reducing residual stress of rare earth heat-treated steel according to claim 1, characterized in that: The method of determining the grinding method of each detection area according to the flatness detection result includes: If the average gray value of the detection area is greater than the standard gray value, the grinding method is to grind the raised area and then refine the surface; If the average grayscale value of the detection area is less than or equal to the standard grayscale value, the grinding method is to refine and grind the corresponding surface of the detection area.

5. The method for reducing residual stress of rare earth heat-treated steel according to claim 1, characterized in that: Determine whether to perform surface grinding on the initially stress-reduced steel material according to the residual stress treatment remaining parameters, include, If the residual stress treatment leftover parameter is greater than or equal to the standard treatment leftover parameter, no surface grinding is performed on the initially stress-reduced steel; If the residual stress treatment leftover parameter is less than the standard treatment leftover parameter, the initially stress-reduced steel is subjected to surface grinding.

6. The method for reducing residual stress of rare earth heat-treated steel according to claim 5, characterized in that: The criteria for adjusting the stress treatment category are determined based on the number of pre-treated steel materials corresponding to different stress treatment categories, including: If several consecutive pre-treated steels are of the direct stress treatment category, the standard residual stress distribution parameters are reduced; If several consecutive pre-treated steels are of the indirect stress treatment type, the standard residual stress distribution parameters are increased.

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