A method for quantitatively characterizing the degree of plastic deformation of a machined surface

Abstract

The application relates to a method for quantitatively representing the plastic deformation degree of a machined surface, which comprises the following steps: S1, cutting a test sample perpendicularly to the measured surface of a part; S2, obtaining the yield strength sigma of each measured layer material from the measured surface to the subsurface of the test sample sp , the distance h of the measured layer from the measured surface, and the yield strength sigma of the material matrix of the part so ; S3, determining the maximum influence depth h max of the plastic deformation of the machined surface and the plastic deformation rate S of each measured layer material with the increase of the layer number; and S4, establishing a curve of the change rule relationship between S and h by taking the distance h of the measured layer from the measured surface as the horizontal coordinate and the plastic deformation rate S of each measured layer material in the direction from the machined surface to the subsurface as the vertical coordinate, so as to realize the quantitative representation of the plastic deformation degree of the machined surface.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of machining surface quality measurement and evaluation, and particularly relates to a method for quantitatively representing the plastic deformation degree of a machining surface. BACKGROUND

[0002] The plastic deformation degree of a machining surface is one of the main factors affecting the fatigue resistance of a test piece, and at present, the quantified influence rule of the plastic deformation degree of a machining surface on the fatigue resistance of a test piece cannot be directly established in the research and engineering application of machining surface integrity, and the main reason is that the quantified representation of the plastic deformation degree of a machining surface has not been achieved.

[0003] At present, the thickness of surface structure deformation is generally used to indirectly reflect the degree of surface plastic deformation, but from the formation mechanism, there is no strict connection between the two, especially in the comparison of the plastic deformation degree of the surface formed by different machining methods, and the scientificity needs to be improved. On the other hand, whether the surface structure is deformed and the range of the structure deformation are mainly determined by the observer observing the deformation of the surface structure grain, so there is a large subjective in the measurement of the plastic deformation thickness of the machining surface, and it is very difficult to accurately represent the plastic deformation degree of the machining surface by using the deformation of the surface structure grain. SUMMARY

[0004] (I) Technical problems to be solved

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

[0006] (II) Technical solutions

[0007] In order to achieve the above-mentioned purpose, the main technical solution adopted by the present application comprises:

[0008] The embodiment of the present application provides a method for quantitatively representing the plastic deformation degree of a machining surface, comprising: step S1, cutting perpendicular to the measured surface of a part to prepare a test test piece with a detection plane; step S2, layering the measured surface of the test test piece to the subsurface of the test test piece along the normal direction of the measured surface of the test test piece, and sequentially acquiring the yield strength σ sp of each measured layer material from the measured surface of the test test piece to the subsurface of the test test piece based on the detection plane, the distance h of the measured layer from the measured surface, and the yield strength σ so of the material matrix of the part; and step S3, with the increase of the number of layers, if it is determined that the yield strength σ spIf the changes in m consecutive times are all within the first preset range, then the maximum influence depth h of the plastic deformation of the processed surface is determined. max And will have the maximum impact depth h max The yield strength σ of each layer of the corresponding multilayer material sp Compared to the yield strength σ of the component material matrix so The percentage increase is taken as the plastic deformation rate S of the corresponding tested layer material; where m is a preset first positive integer; Step S4, establish a coordinate system relating the plastic deformation rate S of the processed surface to the distance h, and set the maximum influence depth h as the coordinate system. max The yield strength σ of each layer of the corresponding multilayer material sp The horizontal axis of the relational coordinate system is used as the horizontal axis, and the plastic deformation rate S of the processed surface of each measured layer material is used as the vertical axis of the relational coordinate system to achieve a quantitative characterization of the degree of plastic deformation of the machined surface.

[0009] In one possible embodiment, the method for cutting the surface of the part being measured is electrical discharge machining, cutting, or grinding, and the cut surface is then subjected to rough polishing and fine polishing operations.

[0010] In one possible embodiment, the yield strength σ of each tested layer material sp and the yield strength σ of the component material matrix so All of them were obtained through nanoindentation.

[0011] In one possible embodiment, the interlayer spacing between two adjacent layers in the multilayer material of the surface under test is 2-10 μm.

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

[0013] Nanoindentation measurements were performed at a designated location greater than 5 mm below the test surface of the test specimen, along the normal direction of the test surface. The yield strength of the material at the corresponding location was taken as the yield strength σ of the matrix material of the part. so ;or,

[0014] As the number of delaminations increases, the yield strength σ sp The changes in n consecutive measurements are all within the second preset range, and the yield strength σ measured in n measurements is... sp The average value is used as the yield strength σ of the matrix material of the part. so Where n is a preset second positive integer.

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

[0016]

[0017] (III) Beneficial Effects

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

[0019] The embodiment of the present application provides a kind of quantitative characterization method of plastic deformation degree of machined surface, by the influence mechanism of plastic deformation degree of machined surface to material mechanics performance, it is combined with the characteristics of plastic deformation of machined surface, along the direction perpendicular to the processing surface, the surface plastic deformation is layered, and the existing nanoindentation measurement method is used to obtain the mechanical property curve of each measured layer material.And the percentage of the yield strength of each measured layer material compared with the yield strength of matrix material increases is defined as the plastic deformation rate of processing surface, so as to realize the accurate quantitative characterization of plastic deformation degree of machined surface, and lay the foundation for the quantitative influence of plastic deformation degree of machined surface on the fatigue resistance of test piece.

[0020] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application, it should be understood that the following drawings only show some embodiments of the present application, therefore should not be regarded as the limitation to the scope, for ordinary skilled in the art, without paying creative labor, other related drawings can also be obtained according to these drawings.

[0022] Figure 1 The flow chart of the quantitative characterization method of plastic deformation degree of machined surface provided by the embodiments of the present application is shown;

[0023] Figure 2 The cross-sectional view of the measured surface of the test piece provided by the embodiments of the present application is shown;

[0024] Figure 3 The detection position distribution diagram along the normal direction of the measured surface provided by the embodiments of the present application is shown;

[0025] Figure 4 The schematic diagram of the relationship between the plastic deformation rate S of processing surface and distance h is shown. DETAILED DESCRIPTION

[0026] In order to better explain the present application, in order to facilitate understanding, the present application is described in detail by specific implementation mode, combined with the drawings.

[0027] In order to solve the problem that the degree of plastic deformation of the machined surface layer cannot be accurately quantified in the prior art, the embodiment of the present application provides a method for quantitatively characterizing the degree of plastic deformation of the machined surface. Starting from the influence mechanism of the degree of plastic deformation of the machined surface on the mechanical properties of the material, combining the characteristics of the plastic deformation of the machined surface, the surface plastic deformation is layered in the direction perpendicular to the machined surface, and the existing nanoindentation measurement method is used to obtain the mechanical property curve of each measured layer material. And the percentage increase of 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 machined surface, so as to realize the accurate quantitative characterization of the degree of plastic deformation of the machined surface, and lay a foundation for studying the quantitative influence of the degree of plastic deformation of the machined surface on the fatigue resistance of the test piece.

[0028] In order to better understand the above technical solutions, the exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present application can be more clearly, thoroughly understood, and the scope of the present application can be completely conveyed to those skilled in the art.

[0029] Please refer to Figure 1 , Figure 1 A flow chart of a method for quantitatively characterizing the degree of plastic deformation of the machined surface provided by the embodiment of the present application is shown. It should be understood that the quantitatively characterizing 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 quantitatively characterizing method comprises:

[0030] Step S110, cutting the measured surface of the part vertically to prepare a test specimen with a detection plane.

[0031] Specifically, the method of cutting the measured surface of the part can adopt electrical machining, cutting machining or grinding machining, etc., and the cut surface also needs to be rough polished and fine polished to ensure that the cut surface after machining is smooth and cannot introduce the influence of the cutting machining method on the quality of the cut surface.

[0032] For example, please refer to Figure 2 , Figure 2 A cutting schematic diagram of the measured surface of the test piece provided by the embodiment of the present application is shown. As Figure 2 shown, the measured surface (2) of the part (1) is cut by using the cutting plane (3), and the cut plane of the part is used as the detection plane (4), so as to obtain a test specimen with the detection plane (4).

[0033] Step S120, layering from the measured surface of the test specimen to the subsurface of the test specimen along the normal direction of the measured surface of the test specimen, and sequentially obtaining the yield strength σ of each measured layer material from the measured surface of the test specimen to the subsurface of the test specimen based on the detection plane sp , the yield strength σ of the part material matrix so , and the detection point to the distance h of the measured surface of the test specimen sp for detecting the yield strength σ of each measured layer material.

[0034] It should be understood that the layer spacing of any two adjacent layers of the multi-layer material from the measured surface of the test specimen to the subsurface of the test specimen is 2-10 μm, and the smaller the layer spacing, the more accurate the distribution law of the plastic deformation degree of the processed surface is described, but the smaller the layer spacing, the more the measurement times, and the more difficult the measurement.

[0035] For example, the layer spacing of any two adjacent layers of the multi-layer material from the measured surface of the test specimen to the subsurface of the test specimen is 5 μm.

[0036] For another example, the layer spacing of any two adjacent layers of the multi-layer material from the measured surface of the test specimen to the subsurface of the test specimen is not the same, as long as the layer spacing is within the range of 2-10 μm.

[0037] It should also be understood that the specific method of sequentially obtaining the yield strength σ of each measured layer material from the measured surface of the test specimen to the subsurface of the test specimen based on the detection plane sp , the yield strength σ of the part material matrix so may also be set according to actual needs.

[0038] Optionally, the yield strength σ of each measured layer material sp and the yield strength σ of the part material matrix so are obtained by a nano indentation method. The nano indentation method has the advantages of small test point and stable test precision.

[0039] For example, a nano indentation measurement is performed on a specified position greater than 5 mm below the measured surface of the test specimen along the normal direction of the measured 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 part material matrix so ; or

[0040] As the number of layering increases, the yield strength σ sp changes continuously n times, and the average value of the yield strength σ sp measured n times is taken as the yield strength σ of the part 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 this application are not limited thereto.

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

[0043] For example, the second preset range can be 0 to 10%.

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

[0045] It should be understood that the formula for calculating 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 this application are not limited thereto.

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

[0049] For example, the first preset range can also be 0 to 10%.

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

[0051] Step S140: Establish a coordinate system relating the plastic deformation rate S of the processed surface to the distance h, and set the maximum influence depth h as the coordinate system. max The yield strength σ of each layer of the corresponding multilayer material sp The horizontal axis of the relational coordinate system is used as the horizontal axis, and the plastic deformation rate S of the processed surface of each measured layer material is used as the vertical axis of the relational coordinate system to achieve a quantitative characterization of the degree of plastic deformation of the machined surface.

[0052] Specifically, the distance h of the detection point to the measured surface of the test specimen is taken as the abscissa, and the plastic deformation rate S of the machined surface of each measured layer material is taken as the ordinate, to establish a relationship coordinate system between the plastic deformation rate of the machined surface and the detection position, and the maximum influence depth h sp The yield strength σ max of each measured layer material in the corresponding multi-layer material is taken as the abscissa, and the plastic deformation rate S of the machined surface is taken as the ordinate, to realize the quantitative characterization of the plastic deformation degree of the machined surface. sp

[0053] For example, please refer to Figure 3 , Figure 3 A detection position distribution diagram along the normal direction of the measured surface is shown. As Figure 3 shown, the maximum influence depth h max is determined to be 50 μm, and a relationship coordinate system as Figure 4 shown is established with the maximum influence depth h max and the corresponding plastic deformation rate S of the machined surface.

[0054] Therefore, by means of the above technical solution, the present application starts from the influence mechanism of the plastic deformation degree of the machined surface on the mechanical properties of the material, combines the distribution characteristics of the surface plastic deformation of the material after mechanical machining, layers the surface plastic deformation along the direction perpendicular to the machined surface, and adopts the measurement method of nano indentation to obtain the mechanical property curve of each measured layer material. 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, so as to realize the accurate quantitative characterization of the plastic deformation degree of the machined surface, and the influence depth of the corresponding plastic deformation layer is obtained. By adopting the method provided by the present application, starting from the formation mechanism of the plastic deformation of the machined surface material, a method capable of accurately quantifying the plastic deformation degree of the machined surface is provided, which avoids the randomness and subjectivity of determining the plastic deformation degree of the machined surface and its influence depth by observation method, reduces the difficulty of accurately characterizing the plastic deformation degree of the machined surface, and provides a basis for scientifically and quantitatively studying the influence law and mechanism of the plastic deformation degree of the machined surface on the fatigue resistance and wear resistance of the part.

[0055] It should be understood that the above quantitative characterization method of the plastic deformation degree of the machined surface is only exemplary, and those skilled in the art can make various modifications based on the above method, and the modified scheme also belongs to the protection scope of the present application.

[0056] ​Those skilled in the art will appreciate that embodiments of the present application can be readily used as a method, a system or a computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer readable program code thereon for use by or in connection with an instruction execution system. For the purposes of this description, a computer-usable or computer readable storage medium can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

[0057] The present application is described in reference to the flowchart and / or block diagrams of the method, apparatus (system) and computer program product according to embodiments of the present application. It will be understood that each block of the flowchart and / or block diagrams, and combinations of blocks in the flowchart and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, implement the functions specified in the flowchart and / or block diagram block or blocks.

[0058] It should be noted that any references made herein to elements or components should not be construed as limiting the scope of the claims to having only those specific elements. Rather, the language is intended to encompass all possible combinations of elements, where the elements do not mutually exclude each other. It is further noted that the use of "a", "an", "the" and similar referents in the description are intended to be inclusive of the plural, unless the context clearly indicates otherwise. Furthermore, the description is intended to cover all possible combinations of the described features, materials, and / or characteristics, unless the context clearly indicates otherwise. It is further noted that the description is intended to cover all possible combinations of the described features, materials, and / or characteristics, unless the context clearly indicates otherwise.

[0059] Moreover, it should be noted that the terms "one embodiment", "some embodiments", "an embodiment", "an example", "specific example" or "some examples" as used herein are meant to be inclusive of all embodiments and examples falling within the scope of the present application. The above described embodiments are intended to be illustrative only and not limiting of the scope of the present application. Many variations of the described embodiments are possible, and the scope of the present application is not limited to the described embodiments. The scope of the present application is limited only by the claims.

[0060] While the preferred embodiments of the application have been described, additional variations and modifications can be made to the embodiments by those skilled in the art once they have the benefit of the foregoing description. Therefore, the claims should be construed to include all embodiments and equivalents falling within the scope of the present application.

[0061] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A method of quantitatively characterizing the degree of plastic deformation of a machined surface, characterized in that, The application relates to a method for measuring the surface roughness of a workpiece, and a testing device thereof. The step S1 comprises cutting the surface of the workpiece perpendicularly to the surface to be measured, so as to prepare a testing sample with a testing plane; In step S2, the measured surface of the test specimen is layered from the surface to the subsurface of the test specimen in the normal direction of the measured surface of the test specimen, and the yield strength σ of each measured layer material is sequentially obtained from the measured surface to the subsurface of the test specimen based on the detection plane sp and the distance h of the measured layer from the measured surface, the yield strength σ of the base material of the part so . Step S3, with the increase of the layer number, if it is determined that the yield strength σ sp The change amount is within the first preset range for m times in succession, the maximum influence depth h of the plastic deformation of the processing surface is determined max And the maximum influence depth h max The yield strength σ sp The yield strength σ so The percentage of the increase of the yield strength σ of the part material matrix is taken as the plastic deformation rate S of the corresponding measured layer material; wherein m is a preset first positive integer; Step S4, establishing the relationship coordinate system of the machining surface plastic deformation rate S and the distance h, and taking the maximum influence depth h max Corresponding to the yield strength σ of each measured layer material in the multi-layer material sp Taking the machining surface plastic deformation rate S of each measured layer material as the ordinate of the relationship coordinate system, the transverse coordinate of the relationship coordinate system is realized, and the quantitative characterization of the degree of machining surface plastic deformation is realized.

2. The method of claim 1, wherein, The cutting method of the surface of the workpiece is electro-processing, cutting or grinding, and rough polishing and fine polishing operations are carried out on the cut surface.

3. The method of claim 1, wherein, the yield strength σ of each of the layer materials under test sp and the yield strength σ of the base material of the part so are obtained by means of nanoindentation.

4. The method of claim 3, wherein, The layer spacing of two adjacent layers in the multilayer material is 2-10 mu m.

5. The method of claim 1 or 3, wherein, The yield strength σ of the part material matrix so The acquisition process is as follows: a nanoindentation measurement is made on a specified location greater than 5 mm below the measured surface of the test specimen in the normal direction of the measured surface of the test specimen, and the resulting yield strength of the material at the corresponding location is taken as the yield strength σ so ; or, With the increase of the number of layering, the yield strength σ sp The average value of the yield strength σ sp of the n times of measurement is taken as the yield strength σ so of the part material matrix; wherein n is a preset second positive integer.

6. The method of claim 1, wherein, The plastic deformation rate S of the processing surface is

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