Quantitative characterization method for plastic deformation degree of machined surface

Abstract

The invention relates to a quantitative characterization method for the plastic deformation degree of a machining surface, and the method comprises the steps: S1, carrying out the sectioning perpendicular to a to-be-tested surface of a part, and preparing a test piece; s2, sequentially obtaining the yield strength sigma sp of each tested layer material, the distance h from the tested layer to the tested surface and the yield strength sigma so of the part material matrix from the tested surface of the test piece to the subsurface of the test piece; s3, determining the maximum influence depth hmax of the plastic deformation of the machined surface and the plastic deformation rate S of the material of each measured layer along with the increase of the number of layers; and S4, establishing a change rule relation curve of S and h by taking the distance h from the measured layer to the measured surface as an abscissa and the plastic deformation rate S of the material of each measured layer in the direction from the machining surface to the subsurface as an ordinate, so as to realize quantitative characterization of the plastic deformation degree of the machining surface.

Description

Technical Field

[0001] The invention relates to the field of mechanical processing surface quality measurement and evaluation, and in particular to a quantitative characterization method for the degree of plastic deformation of a mechanical processing surface. Background Art

[0002] The degree of plastic deformation of the machined surface is one of the main factors affecting the fatigue resistance of the specimen. However, in the current research on the integrity of the machined surface and engineering applications, it is impossible to directly establish the quantitative influence of the degree of plastic deformation of the machined surface on the fatigue resistance of the specimen. The main reason is that the quantitative expression of the degree of plastic deformation of the machined surface has not been achieved.

[0003] At present, the thickness of the surface tissue deformation is generally used to indirectly reflect the degree of surface plastic deformation. However, from the perspective of the formation mechanism, there is no strict connection between the two, especially in terms of the comparison of the degree of surface plastic deformation formed by different mechanical processing methods, its scientificity needs to be improved. On the other hand, whether the surface tissue is deformed and the area of ​​tissue deformation are mainly determined by the deformation of the surface tissue grains observed by the measurer. Therefore, the measurement of the thickness of the plastic deformation of the machined surface is also highly subjective, so it is very difficult to accurately characterize the degree of plastic deformation of the machined surface by the deformation of the surface tissue grains. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for quantitatively characterizing the degree of plastic deformation of a machined surface, which solves the technical problem in the prior art that the degree of plastic deformation of a machined surface layer material cannot be accurately quantitatively characterized.

[0006] (II) Technical solution

[0007] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0008] The embodiment of the present invention provides a method for quantitatively characterizing the degree of plastic deformation of a machined surface, comprising: step S1, cutting perpendicularly to the tested surface of a part to prepare a test specimen with a detection plane; step S2, layering the tested surface of the test specimen to the sub-surface of the test specimen along the normal direction of the tested surface of the test specimen, and obtaining the yield strength σ of each tested layer material in sequence from the tested surface of the test specimen to the sub-surface of the test specimen based on the detection plane. sp As well as the distance h between the measured layer and the measured surface, the yield strength σ of the component material matrix so ; Step S3, as the number of layers increases, if the yield strength σ is determined spIf the changes for m consecutive times are all within the first preset range, the maximum influence depth h of the plastic deformation of the machined surface is determined. max , and the maximum impact depth h max The yield strength σ of each layer of the corresponding multilayer material is sp Compared to the yield strength of the component material matrix σ so The percentage of increase is taken as the plastic deformation rate S of the machining surface of the corresponding layer material; wherein m is a preset first positive integer; step S4, establishing a coordinate system of the relationship between the plastic deformation rate S of the machining surface and the distance h, and setting the maximum impact depth h max The yield strength σ of each layer of the corresponding multilayer material is sp As the abscissa of the relational coordinate system, the plastic deformation rate S of the machined surface of each measured layer material is taken as the ordinate of the relational coordinate system to achieve quantitative characterization of the degree of plastic deformation of the machined surface.

[0009] In a possible embodiment, the sectioning method of the measured surface of the part is electrical machining, cutting or grinding, and the sectioned surface is subjected to rough polishing and fine polishing operations.

[0010] In a possible embodiment, the yield strength σ of each measured layer material is sp and the yield strength of the component material matrix σ so All of them were obtained by nanoindentation method.

[0011] In a possible embodiment, the interlayer distance between two adjacent layers of the multilayer material on the measured surface is 2-10 μm.

[0012] In one possible embodiment, the yield strength σ of the component material matrix so The acquisition process is:

[0013] Along the normal direction of the test specimen's surface, nanoindentation measurement is performed at a designated position greater than 5 mm below the test specimen's surface, and the yield strength of the material at the corresponding position obtained is used as the yield strength σ of the part material matrix. so ;or,

[0014] As the number of delaminations increases, the yield strength σ sp The changes of n consecutive times are all within the second preset range, and the yield strength σ measured n times is sp The average value of is taken as the yield strength σ of the component material matrix so ; Wherein, n is a preset second positive integer.

[0015] In a possible embodiment, the plastic deformation rate S of the machined surface is:

[0016]

[0017] (III) Beneficial effects

[0018] The beneficial effects of the present invention are:

[0019] The embodiment of the present application provides a quantitative characterization method for the degree of plastic deformation of a machined surface. Starting from the mechanism of the influence of the degree of plastic deformation of the machined surface on the mechanical properties of the material, combined with the characteristics of the plastic deformation of the machined surface, the surface plastic deformation is layered in a direction perpendicular to the machined surface, and the mechanical property curve of each measured layer material is obtained by using the existing nanoindentation measurement method. In addition, the percentage increase of the yield strength of each measured layer material compared with the yield strength of the base material is defined as the plastic deformation rate of the machined surface, thereby achieving accurate quantitative characterization of the degree of plastic deformation of the machined surface, and laying a foundation for studying the quantitative influence of the degree of plastic deformation of the machined surface on the fatigue resistance of the specimen.

[0020] In order to make the above-mentioned objectives, features and advantages to be achieved by the embodiments of the present application more obvious and understandable, the following specifically cites preferred embodiments and describes them in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A flow chart showing a method for quantitatively characterizing the degree of plastic deformation of a machined surface provided in an embodiment of the present application is shown;

[0023] Figure 2 A schematic cross-sectional view of a tested surface of a test piece provided in an embodiment of the present application is shown;

[0024] Figure 3 A schematic diagram of the distribution of detection positions along the normal direction of the detected surface provided by an embodiment of the present application is shown;

[0025] Figure 4 A schematic diagram of a coordinate system showing the relationship between a plastic deformation rate S of a machined surface and a distance h provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0026] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0027] In order to solve the problem that the existing technology cannot accurately quantify and characterize the degree of plastic deformation of the machined surface layer material, the embodiment of the present application provides a quantitative characterization method for the degree of plastic deformation of the machined surface, starting from the mechanism of the influence of the degree of plastic deformation of the machined surface on the mechanical properties of the material, combined with the characteristics of the plastic deformation of the machined surface, the surface plastic deformation is layered along the direction perpendicular to the machined surface, and the mechanical property curve of each measured layer material is obtained by using the existing nanoindentation measurement method. In addition, the percentage increase of the yield strength of each measured layer material compared with the yield strength of the base material is defined as the plastic deformation rate of the machined surface, thereby achieving accurate quantitative characterization of the degree of plastic deformation of the machined surface, and laying a foundation for studying the quantitative influence of the degree of plastic deformation of the machined surface on the fatigue resistance of the specimen.

[0028] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0029] See also Figure 1 , Figure 1 A flowchart of a quantitative characterization method for the degree of plastic deformation of a machined surface provided by an embodiment of the present application is shown. It should be understood that the quantitative characterization method can be executed by an electronic device, and the specific device of the electronic device can be set according to actual needs, and the embodiment of the present application is not limited thereto. Specifically, the quantitative characterization method includes:

[0030] Step S110, cutting the part perpendicularly to the surface to be tested to prepare a test specimen with a detection plane.

[0031] Specifically, the method of sectioning the measured surface of the part can be electrical machining, cutting or grinding, and the sectioned surface also needs to be rough polished and fine polished to ensure that the sectioned surface is smooth after processing, and the sectioning method cannot affect the sectioned surface quality.

[0032] For example, see Figure 2 , Figure 2 FIG. 2 shows a schematic cross-sectional view of a test piece surface to be tested provided in an embodiment of the present application. Figure 2 As shown, the measured surface (2) of the part (1) is sectioned using a sectioning plane (3), and the sectioned plane of the part is used as a detection plane (4), thereby obtaining a test specimen having a detection plane (4).

[0033] Step S120, along the normal direction of the tested surface of the test specimen, the tested surface of the test specimen is layered to the sub-surface of the test specimen, and based on the detection plane, the yield strength σ of each tested layer material is obtained in sequence from the tested surface of the test specimen to the sub-surface of the test specimen. sp , the yield strength of the component material matrix σ so and used to detect the yield strength σ of each layer material sp The distance h from the detection point to the measured surface of the test specimen.

[0034] It should be understood that the interlayer spacing between two adjacent layers of material in the multilayer material from the tested surface to the sub-surface of the test specimen is 2-10μm, and the smaller the interlayer spacing, the more accurate the description of the distribution law of the degree of plastic deformation of the processed surface. However, the smaller the interlayer spacing, the more times of measurement and the greater the measurement difficulty.

[0035] For example, the interlayer spacing between any two adjacent layers of the multilayer material from the tested surface of the test specimen to the subsurface of the test specimen is 5 μm;

[0036] For another example, the interlayer spacings between any two adjacent layers of the multilayer material from the tested surface to the subsurface of the test specimen are different, as long as the interlayer spacing is within the range of 2-10 μm.

[0037] It should also be understood that based on the detection plane, the yield strength σ of each layer material to be tested is obtained in sequence from the tested surface of the test specimen to the sub-surface of the test specimen. sp , the yield strength of the component material matrix σ so The specific method can also be set according to actual needs.

[0038] Optionally, the yield strength σ of each measured layer material sp and the yield strength of the component material matrix σ so All of them are obtained by nanoindentation method, which has the advantages of small test point and stable test accuracy.

[0039] For example, along the normal direction of the tested surface of the test specimen, a nanoindentation measurement is performed at a designated position greater than 5 mm below the tested surface of the test specimen, and the yield strength of the material at the corresponding position obtained is used as the yield strength σ of the matrix of the part material so ;or,

[0040] As the number of delaminations increases, the yield strength σ sp The changes of n consecutive times are all within the second preset range, and the yield strength σ measured n times is sp The average value of is taken as the yield strength σ of the component material matrix so ; Wherein, n is a preset second positive integer.

[0041] It should also be understood that the specific value of n and the specific range of the second preset range can be set according to actual needs, and the embodiments of the present application are not limited to this.

[0042] For example, n can be any positive integer from 3 to 5;

[0043] For another example, the second preset range may be 0-10%.

[0044] Step S130: As the number of layers increases, if the yield strength σ sp If the changes for m consecutive times are all within the first preset range, the maximum influence depth h of the plastic deformation of the machined surface is determined. max , and the maximum impact depth h max The yield strength σ of each layer of the corresponding multilayer material is sp Compared to the yield strength of the component material matrix σ so The increase percentage is used as the plastic deformation rate S of the processing surface of the corresponding layer material being measured. The increase percentage can be used to quantitatively characterize the degree of plastic deformation of the processing surface; m is a preset first positive integer.

[0045] It should be understood that the calculation expression of the plastic deformation rate S of the machined surface is as follows:

[0046]

[0047] It should also be understood that the specific value of m and the specific range of the first preset range can also be set according to actual needs, and the embodiments of the present application are not limited to this.

[0048] For example, m can also be any positive integer from 3 to 5;

[0049] For another example, the first preset range may also be 0-10%.

[0050] It should also be understood that in determining the yield strength σ sp When the changes for m consecutive times are all within the first preset range, the height of the layer closest to the measured surface among the m layers from the measured surface can be taken as the maximum influence depth h max .

[0051] Step S140, establish a coordinate system for the relationship between the plastic deformation rate S of the machined surface and the distance h, and set the maximum impact depth h max The yield strength σ of each layer of the corresponding multilayer material is sp As the abscissa of the relational coordinate system, the plastic deformation rate S of the machined surface of each measured layer material is taken as the ordinate of the relational coordinate system to achieve quantitative characterization of the degree of plastic deformation of the machined surface.

[0052] Specifically, it is used to detect the yield strength σ of each layer material being tested. sp The distance h from the detection point to the tested surface of the test specimen is taken as the horizontal coordinate, and the plastic deformation rate S of the machining surface of each layer of material being tested is taken as the vertical coordinate to establish the relationship between the plastic deformation rate of the machining surface and the detection position coordinate system, and the maximum impact depth h is taken as the vertical coordinate. max The yield strength σ of each layer of the corresponding multilayer material is sp And the plastic deformation rate S of the machined surface are used to quantitatively characterize the degree of plastic deformation of the machined surface.

[0053] For example, see Figure 3 , Figure 3 FIG. 2 shows a schematic diagram of the distribution of detection positions along the normal direction of the detected surface provided by an embodiment of the present application. Figure 3 As shown, in determining the maximum impact depth h max is 50 μm, and with the maximum impact depth h max And its corresponding processing surface plastic deformation rate S is established as follows Figure 4 The relational coordinate system shown.

[0054] Therefore, with the help of the above technical solution, the present application starts from the mechanism of the influence of the degree of plastic deformation of the machining surface on the mechanical properties of the material, combines the distribution characteristics of the surface plastic deformation of the material after mechanical processing, layers the surface plastic deformation in the direction perpendicular to the machining surface, and uses the nanoindentation measurement method to obtain the mechanical property curve of each measured layer material. In addition, the percentage of the increase in the yield strength of each measured layer material compared with the yield strength of the matrix material is defined as the plastic deformation rate of the machining surface, thereby achieving an accurate quantitative characterization of the degree of plastic deformation of the machining surface, and at the same time, obtaining the influence depth of the corresponding plastic deformation layer. The method provided by the present application, starting from the formation mechanism of the plastic deformation of the machining surface material, provides a method that can accurately and quantitatively characterize the degree of plastic deformation of the machining surface, avoids the randomness and subjectivity of using the observation method to determine the degree of plastic deformation of the machining surface and its influence depth, reduces the difficulty of accurately characterizing the degree of plastic deformation of the machining surface, and provides a basis for scientific and quantitative research on the influence law and mechanism of the degree of plastic deformation of the machining surface on the fatigue resistance and wear resistance of parts.

[0055] It should be understood that the above-mentioned method for quantitatively characterizing the degree of plastic deformation of a machined surface is merely exemplary, and those skilled in the art may perform various modifications based on the above-mentioned method, and the modified schemes also fall within the scope of protection of the present application.

[0056] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0057] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions.

[0058] It should be noted that in the claims, any reference numerals placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the claims enumerating several means, several of these means may be embodied by the same hardware. The use of the words first, second, third, etc., is for convenience of expression only and does not indicate any order. These words may be understood as part of the component name.

[0059] In addition, it should be noted that, in the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0060] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments after knowing the basic creative concept. Therefore, the claims should be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0061] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include these modifications and variations.

Claims

1. A method for quantitatively characterizing the degree of plastic deformation of a machined surface, characterized in that: include: Step S1, cutting perpendicularly to the surface of the part to be tested to prepare a test specimen with a detection plane; Step S2, along the normal direction of the tested surface of the test specimen, the tested surface of the test specimen to the sub-surface of the test specimen are layered, and based on the detection plane, the yield strength σ of each tested layer material is obtained in sequence from the tested surface of the test specimen to the sub-surface of the test specimen. sp As well as the distance h between the measured layer and the measured surface, the yield strength σ of the component material matrix so ; Step S3: As the number of layers increases, if the yield strength σ is determined sp If the changes in the continuous m times are all within the first preset range, the maximum influence depth h of the plastic deformation of the machined surface is determined. max , and the maximum impact depth h max The yield strength σ of each layer of the corresponding multilayer material is sp Compared to the yield strength of the component material matrix σ so The percentage of increase is taken as the plastic deformation rate S of the machining surface of the corresponding measured layer material; wherein m is a preset first positive integer; Step S4, establishing a coordinate system for the relationship between the plastic deformation rate S of the machined surface and the distance h, and calculating the maximum impact depth h max The yield strength σ of each layer of the corresponding multilayer material is sp As the abscissa of the relational coordinate system, the plastic deformation rate S of the machined surface of each measured layer material is taken as the ordinate of the relational coordinate system to achieve quantitative characterization of the degree of plastic deformation of the machined surface.

2. The quantitative characterization method according to claim 1, characterized in that: The sectioning method of the measured surface of the part is electrical machining, cutting or grinding, and the sectioned surface is subjected to rough polishing and fine polishing operations.

3. The quantitative characterization method according to claim 1, characterized in that: The yield strength σ of each measured layer material sp and the yield strength σ of the matrix material of the part so All of them were obtained by nanoindentation method.

4. The quantitative characterization method according to claim 3, characterized in that: The interlayer distance between two adjacent layers of materials in the multilayer material is 2-10 μm.

5. The quantitative characterization method according to claim 1 or 3, characterized in that: The yield strength σ of the matrix of the part material so The acquisition process is: Along the normal direction of the tested surface of the test specimen, a nanoindentation measurement is performed at a designated position greater than 5 mm below the tested surface of the test specimen, and the yield strength of the material at the corresponding position obtained is taken as the yield strength σ of the matrix of the part material so ;or, As the number of delaminations increases, the yield strength σ sp The changes of the n consecutive times are all within the second preset range, and the yield strength σ measured n times is sp The average value is taken as the yield strength σ of the matrix material of the part so ; Wherein, n is a preset second positive integer.

6. The quantitative characterization method according to claim 1, characterized in that: The plastic deformation rate S of the machined surface is:

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