Laser shock peening method for inner hole of part with non-uniform structure

Abstract

The invention relates to the technical field of laser shock peening, in particular to a laser shock peening method for an inner hole of a part with a non-uniform structure, which comprises the following steps of: partitioning the inner hole of the part with the non-uniform structure along the circumferential direction of the hole according to the structure thickness, and calculating the average thickness of each partition; respectively designing a plurality of single-hole test pieces with uniform wall thickness, wherein the single-hole test pieces are the same as the non-uniform structural parts in material and hole diameter, and the wall thickness of each single-hole test piece is the same as the average thickness of the corresponding subarea; respectively carrying out laser shock peening on the single-hole test pieces with different wall thicknesses, and screening out laser shock peening process parameters of which the hole wall peening performance of each single-hole test piece meets a design value; and performing laser shock peening on the inner hole of the part with the non-uniform structure by adopting the laser shock peening process parameters. The laser shock peening method for the inner hole of the part with the non-uniform structure aims at solving the problem that the peening effect is poor due to the fact that the hole diameter is increased and is not uniform after laser shock peening.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser shock peening, in particular to a laser shock peening method for a hole in a non-uniform structure part. BACKGROUND

[0002] The connecting hole of a metal part is a typical concentrated load transmission channel, and the connecting hole is in contact with other structures. In a service environment of alternating load, there is a small relative sliding between the hole wall of the connecting hole and the matching structure, which causes the micro-motion fatigue cracks on the hole wall of the connecting hole, and then evolves into conventional cracks to cause fatigue fracture. Laser shock peening is a surface strengthening technology that uses the plasma shock wave effect generated by the nanosecond pulse laser acting on the surface of the material to generate a residual compressive stress distribution on the surface of the material. The hole wall of the connecting hole is usually subjected to laser shock peening by using an oblique incident beam, and a residual compressive stress distribution (the depth can exceed 1 mm) is introduced on the hole wall, which can significantly improve the micro-motion fatigue performance of the metal part. The connecting hole is a weak fatigue part of the metal part, and therefore the laser shock peening of the connecting hole is a key technology to improve the service performance of the metal part. Due to the structural interference of the connecting hole, the laser beam cannot be perpendicular to the surface of the hole wall to implement laser shock peening, and therefore a laser beam with a certain inclination angle to the surface of the hole wall is usually used for laser shock peening (the angle between the surface of the hole wall and the optical axis of the laser beam is defined as the shock angle), and the laser beam forms a strengthening spot on the surface of the hole wall. The strengthening spot is scanned according to a specified path by moving the laser beam or the part, so as to realize the surface strengthening of the hole wall and cover the strengthening.

[0003] After laser shock peening, plastic deformation occurs on the surface of the hole wall, which causes the hole diameter to increase. The hole diameter increase degree is related to the structure of the connecting hole, and generally the greater the thickness of the hole structure, the smaller the hole diameter increase caused by the same laser shock peening, and vice versa. For the hole in a non-uniform structure part, the hole diameter increases unevenly after laser shock peening, which reduces the roundness of the hole.

[0004] Therefore, the present application provides a laser shock peening method for a hole in a non-uniform structure part. SUMMARY

[0005] (1) Technical problem to be solved The present application provides a laser shock peening method for a hole in a non-uniform structure part, which solves the technical problem of poor strengthening effect caused by uneven hole diameter increase after laser shock peening.

[0006] (2) Technical scheme The application provides a laser shock peening method for a non-uniform structure part inner hole, comprising the following steps: The inner hole of the non-uniform structure part is divided along the hole circumference according to the structure thickness, and the average thickness of each division is calculated; A plurality of single-hole samples with uniform wall thickness are designed, which are the same as the material of the non-uniform structure part and have the same hole diameter, and the wall thickness of each single-hole sample is the same as the average thickness of the corresponding division; The single-hole samples with different wall thicknesses are subjected to laser shock peening, and the laser shock peening process parameters of each single-hole sample are screened out, which meet the design value of the hole wall strengthening performance; The inner hole of the non-uniform structure part is subjected to laser shock peening by using the laser shock peening process parameters.

[0007] Further, the hole wall strengthening performance at least includes residual stress and surface roughness.

[0008] Further, the residual stress is ≤-100 MPa.

[0009] Further, the surface roughness Ra is ≤1.6.

[0010] Further, the laser shock peening process parameters at least include impact angle, laser power density, pulse width, overlap rate, coverage rate and strengthening light spot motion trajectory.

[0011] Further, the impact angle ranges from 45° to 75°.

[0012] Further, the laser power density is 3-12 GW / cm 2 .

[0013] Further, the laser shock peening of the single-hole samples with different wall thicknesses is performed, and the laser shock peening process parameters of each single-hole sample are screened out, which meet the design value of the hole wall strengthening performance, and the method comprises the following steps: The hole diameter of each single-hole sample corresponding to the laser shock peening process parameters is measured to obtain the corresponding relationship between the laser shock peening process parameters of the single-hole samples with different wall thicknesses and the hole diameter increment; The laser shock peening process parameters of each division of the inner hole of the non-uniform structure part are determined according to the hole diameter increment requirement of the inner hole of the non-uniform structure part and the corresponding relationship.

[0014] Further, before the inner hole of the non-uniform structure part is subjected to laser shock peening by using the laser shock peening process parameters, the method further comprises: The non-uniform structure simulation piece is processed, and the laser shock peening process parameters of each partition are used to perform laser shock peening on the non-uniform structure simulation piece, so that the hole diameter increment meets the hole diameter increment requirement of the non-uniform structure part.

[0015] Further, the laser shock peening process parameters are used to perform laser shock peening on the inner hole of the non-uniform structure part, specifically: The laser shock peening process parameters of each partition of the inner hole of the non-uniform structure part are used to perform laser shock peening processing on the inner hole of the non-uniform structure part.

[0016] (3) Beneficial effects In summary, the inner hole of the non-uniform structure part is partitioned according to different hole wall thicknesses of the inner hole of the non-uniform structure part, and the corresponding laser shock peening process parameters of each partition are determined, which is beneficial to improving the hole diameter increment uniformity of the inner hole of the non-uniform structure after laser shock peening on the premise of improving the fatigue performance of the inner hole. BRIEF DESCRIPTION OF DRAWINGS

[0017] 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. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 is a flowchart of a laser shock peening method for an inner hole of a non-uniform structure part provided by the embodiments of the present application; Figure 2(a) is a structure sectional view of a non-uniform structure part provided by the embodiments of the present application; Figure 2(b) is a structure top view of a non-uniform structure part provided by the embodiments of the present application; Figure 3(a) is a structure sectional view of a first single-hole test piece provided by the embodiments of the present application; Figure 3(b) is a structure top view of a first single-hole test piece provided by the embodiments of the present application; Figure 4(a) is a structure sectional view of a second single-hole test piece provided by the embodiments of the present application; Figure 4(b) is a structure top view of a second single-hole test piece provided by the embodiments of the present application; Figure 5(a) is a structure sectional view of a third single-hole test piece provided by the embodiments of the present application; Figure 5(b) is a structure top view of a third single-hole test piece provided by the embodiments of the present application.

[0019] In the drawings: 1-Non-uniform structure part; 2-Inner hole; 3-A zone; 4-B zone; 5-C zone; 6-First single hole specimen; 7-Second single hole specimen; 8-Third single hole specimen. Detailed Implementation

[0020] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] This invention provides a laser shock peening method for the inner hole of a non-uniform structural part. See [link to relevant documentation]. Figure 1 The method includes the following steps: S100. Divide the inner hole of the non-uniform structural part into sections along the circumferential direction of the hole according to the structural thickness, and calculate the average thickness of each section.

[0024] Specifically, in step S100, the thickness of each part within each partition is relatively close with a small difference, so as to ensure that the laser shock strengthening process parameters of each partition are more in line with the actual situation.

[0025] S200. Design multiple single-hole specimens with uniform wall thickness, using the same material and hole diameter as the non-uniform structural parts. The wall thickness of each single-hole specimen is the same as the average thickness of the corresponding zone.

[0026] Specifically, in step S200, each partition of the non-uniform structure part corresponds to a single-hole specimen with a wall thickness, and the wall thickness of the single-hole specimen is consistent with the average thickness of each partition of the non-uniform structure part.

[0027] S300. Laser shock peening was performed on single-hole specimens with different wall thicknesses, and the laser shock peening process parameters that met the design values ​​for the hole wall strengthening performance of each single-hole specimen were selected.

[0028] Specifically, step S300 may include the following steps: S301. For each single-hole specimen corresponding to the laser shock strengthening process parameters, the aperture is measured to obtain the correspondence between the laser shock strengthening process parameters and the aperture increment for single-hole specimens with different wall thicknesses. S302. Based on the incremental requirements of the inner hole diameter of non-uniform structural parts and in conjunction with the corresponding relationships, determine the laser shock strengthening process parameters for each zone of the inner hole of non-uniform structural parts.

[0029] The hole wall strengthening performance includes at least residual stress and surface roughness, with residual stress ≤ -100 MPa and surface roughness Ra ≤ 1.6. Furthermore, the laser shock peening process parameters include at least the impact angle, laser power density, pulse width, overlap rate, coverage, and the trajectory of the strengthening spot. The impact angle ranges from 45° to 75°, and the laser power density ranges from 3 to 12 GW / cm². 2 .

[0030] S400: Laser shock peening is performed on the inner holes of non-uniform structural parts using laser shock peening process parameters.

[0031] Specifically, in step S400, laser shock peening process parameters for each zone of the inner hole of the non-uniform structure part are used to perform laser shock peening processing on the inner hole of the non-uniform structure part. Depending on the characteristics of the part and the capabilities of the equipment, the laser shock peening beam motion, part motion, or a combination of both can be selected.

[0032] As an optional implementation, before step S400, which involves using laser shock stabilization process parameters to perform laser shock stabilization on the inner hole of a non-uniform structure part, the following steps are also included: machining a non-uniform structure simulation part, and performing laser shock stabilization on the non-uniform structure simulation part using laser shock stabilization process parameters for each zone, so that its hole diameter increment meets the inner hole diameter increment requirements of the non-uniform structure part. The non-uniform structure simulation part is typically a local portion of a non-uniform structure part with an inner hole, which is difficult to test for performance. The non-uniform structure simulation part, however, considers both structural characteristics and allows for performance evaluation through design.

[0033] Example 1 The non-uniform structure part 1 has an inner hole 2. The part material is TC4 titanium alloy. The diameter of the inner hole 2 is ΦH=20mm. The inner hole 2 is divided into three sections: A, B and C, as shown in Figures 2(a) and 2(b). The average wall thicknesses of the holes in sections A 3, B 4 and C 5 are 10mm, 12.5mm and 15mm, respectively.

[0034] Based on the hole wall thickness of partitions A3, B4, and C5, single-hole specimens with uniform wall thickness were designed and fabricated, as shown in Figures 3(a) and 3(b). The first single-hole specimen 6 corresponds to partition A3, as shown in Figures 4(a) and 4(b). The second single-hole specimen 7 corresponds to partition B4, as shown in Figures 5(a) and 5(b). The third single-hole specimen 8 corresponds to partition C5. The hole diameters of the first single-hole specimen 6, the second single-hole specimen 7, and the third single-hole specimen 8 are all ΦH=20mm, and the hole wall thicknesses are 10mm, 12.5mm, and 15mm, respectively.

[0035] Laser shock peening tests were conducted on single-hole specimens with different process parameters. The selected process parameters were: impact angle 45°, laser power density 5 GW / cm². 2 The pulse width is 15ns, the square spot size is 4mm×4mm, the overlap rate is 10%, and the coverage is 200%.

[0036] The residual stress and surface roughness of the reinforced surface of the single-hole specimen were measured. Under the requirements of surface residual stress ≤ -350MPa and surface roughness Ra ≤ 1.6, the process parameter set of the first single-hole specimen 6 is X, the process parameter set of the second single-hole specimen 7 is Y, and the process parameter set of the third single-hole specimen 8 is Z.

[0037] Hole diameter measurements were performed on single-hole specimens corresponding to the process parameter sets X, Y, and Z to obtain the correspondence between the laser shock peening process parameters and the hole diameter increments for the first single-hole specimen 6, the second single-hole specimen 7, and the third single-hole specimen 8. For non-uniform structural parts, the hole diameter increment is within the range [h, H]. Process parameters X0, Y0, and Z0, which have hole diameter increments within the range [h, H], were selected from the process parameter sets X, Y, and Z to form the laser shock peening process parameters for the non-uniform structural internal holes.

[0038] Design and fabricate a structural simulation part containing the typical structural features of the inner hole and its surrounding area, and use laser shock strengthening process parameters for each zone of the inner hole to perform laser shock strengthening on it. After the hole diameter is in the range of [h, H], use the laser shock strengthening process parameters for each zone of the inner hole to perform laser shock strengthening on the non-uniform structure inner hole of the part.

[0039] Example 2 The non-uniform structure part 1 has an inner hole 2. The part material is aluminum alloy. The diameter of the inner hole 2 is ΦH=20mm. The inner hole 2 is divided into three sections: A, B and C, as shown in Figures 2(a) and 2(b). The average wall thicknesses of the holes in sections A 3, B 4 and C 5 are 10mm, 12.5mm and 15mm, respectively.

[0040] Based on the hole wall thickness of partitions A3, B4, and C5, single-hole specimens with uniform wall thickness were designed and fabricated, as shown in Figures 3(a) and 3(b). The first single-hole specimen 6 corresponds to partition A3, as shown in Figures 4(a) and 4(b). The second single-hole specimen 7 corresponds to partition B4, as shown in Figures 5(a) and 5(b). The third single-hole specimen 8 corresponds to partition C5. The hole diameters of the first single-hole specimen 6, the second single-hole specimen 7, and the third single-hole specimen 8 are all ΦH=20mm, and the hole wall thicknesses are 10mm, 12.5mm, and 15mm, respectively.

[0041] Laser shock peening tests were conducted on single-hole specimens with different process parameters. The selected process parameters were: impact angle 45°, laser power density 3GW / cm². 2 The pulse width is 15ns, the square spot size is 4mm×4mm, the overlap rate is 10%, and the coverage is 200%.

[0042] The residual stress and surface roughness of the reinforced surface of the single-hole specimen were measured. Under the requirements of residual stress ≤ -100MPa and surface roughness Ra ≤ 1.6, the process parameter set of the first single-hole specimen 6 is X, the process parameter set of the second single-hole specimen 7 is Y, and the process parameter set of the third single-hole specimen 8 is Z.

[0043] Hole diameter measurements were performed on single-hole specimens corresponding to the process parameter sets X, Y, and Z to obtain the correspondence between the laser shock peening process parameters and the hole diameter increments for the first single-hole specimen 6, the second single-hole specimen 7, and the third single-hole specimen 8. For non-uniform structural parts, the hole diameter increment is within the range [h, H]. Process parameters X0, Y0, and Z0, which have hole diameter increments within the range [h, H], were selected from the process parameter sets X, Y, and Z to form the laser shock peening process parameters for the non-uniform structural internal holes.

[0044] Design and fabricate a structural simulation part containing the typical structural features of the inner hole and its surrounding area, and use laser shock strengthening process parameters for each zone of the inner hole to perform laser shock strengthening on it. After the hole diameter is in the range of [h, H], use the laser shock strengthening process parameters for each zone of the inner hole to perform laser shock strengthening on the non-uniform structure inner hole of the part.

[0045] Example 3 The non-uniform structure part 1 has an inner hole 2. The part material is ultra-high strength steel. The diameter of the inner hole 2 is ΦH=20mm. The inner hole 2 is divided into three sections: A, B and C, as shown in Figures 2(a) and 2(b). The average wall thicknesses of the holes in sections A 3, B 4 and C 5 are 10mm, 12.5mm and 15mm, respectively.

[0046] Based on the hole wall thickness of partitions A3, B4, and C5, single-hole specimens with uniform wall thickness were designed and fabricated, as shown in Figures 3(a) and 3(b). The first single-hole specimen 6 corresponds to partition A3, as shown in Figures 4(a) and 4(b). The second single-hole specimen 7 corresponds to partition B4, as shown in Figures 5(a) and 5(b). The third single-hole specimen 8 corresponds to partition C5. The hole diameters of the first single-hole specimen 6, the second single-hole specimen 7, and the third single-hole specimen 8 are all ΦH=20mm, and the hole wall thicknesses are 10mm, 12.5mm, and 15mm, respectively.

[0047] Laser shock peening tests were conducted on single-hole specimens with different process parameters. The selected process parameters were: impact angle 45°, laser power density 12 GW / cm². 2 The pulse width is 15ns, the square spot size is 4mm×4mm, the overlap rate is 10%, and the coverage is 200%.

[0048] The residual stress and surface roughness of the reinforced surface of the single-hole specimen were measured. Under the requirements of residual stress ≤ -500MPa and surface roughness Ra ≤ 1.6, the process parameter set of the first single-hole specimen 6 is X, the process parameter set of the second single-hole specimen 7 is Y, and the process parameter set of the third single-hole specimen 8 is Z.

[0049] Hole diameter measurements were performed on single-hole specimens corresponding to the process parameter sets X, Y, and Z to obtain the correspondence between the laser shock peening process parameters and the hole diameter increments for the first single-hole specimen 6, the second single-hole specimen 7, and the third single-hole specimen 8. For non-uniform structural parts, the hole diameter increment is within the range [h, H]. Process parameters X0, Y0, and Z0, which have hole diameter increments within the range [h, H], were selected from the process parameter sets X, Y, and Z to form the laser shock peening process parameters for the non-uniform structural internal holes.

[0050] Design and fabricate a structural simulation part containing the typical structural features of the inner hole and its surrounding area, and use laser shock strengthening process parameters for each zone of the inner hole to perform laser shock strengthening on it. After the hole diameter is in the range of [h, H], use the laser shock strengthening process parameters for each zone of the inner hole to perform laser shock strengthening on the non-uniform structure inner hole of the part.

[0051] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0052] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A laser shock peening method for the inner hole of a non-uniform structural part, characterized in that, The method includes the following steps: The inner hole of the non-uniform structural part is divided into sections along the circumference of the hole according to the structural thickness, and the average thickness of each section is calculated. Multiple single-hole specimens with uniform wall thickness and the same material and aperture as the non-uniform structural part are designed respectively. The wall thickness of each single-hole specimen is the same as the average thickness of the corresponding partition. Laser shock strengthening was performed on single-hole specimens with different wall thicknesses, and the laser shock strengthening process parameters that met the design values ​​for the hole wall strengthening performance of each single-hole specimen were selected. The laser shock peening process parameters are used to perform laser shock peening on the inner hole of the non-uniform structure part.

2. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 1, characterized in that, The hole wall strengthening properties include at least residual stress and surface roughness.

3. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 2, characterized in that, The residual stress is ≤-100MPa.

4. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 2 or 3, characterized in that, The surface roughness Ra ≤ 1.

6.

5. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 1, characterized in that, The laser shock peening process parameters include at least the impact angle, laser power density, pulse width, overlap rate, coverage, and the motion trajectory of the peening spot.

6. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 5, characterized in that, The impact angle ranges from 45° to 75°.

7. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 5 or 6, characterized in that, The laser power density is 3–12 GW / cm². 2 .

8. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 1, characterized in that, The process of performing laser shock peening on single-hole specimens with different wall thicknesses and selecting the laser shock peening process parameters that meet the design values ​​for the hole wall strengthening performance of each single-hole specimen specifically includes the following steps: The aperture of each single-hole specimen corresponding to the laser shock strengthening process parameters was measured to obtain the correspondence between the laser shock strengthening process parameters and the aperture increment for single-hole specimens with different wall thicknesses. Based on the required increase in the inner diameter of the non-uniform structural part and the corresponding relationship, the laser shock peening process parameters for each zone of the inner hole of the non-uniform structural part are determined.

9. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 8, characterized in that, Before applying the laser shock peening process parameters to the inner hole of the non-uniform structure part, the process further includes: A non-uniform structure simulation part is fabricated, and the non-uniform structure simulation part is subjected to laser shock strengthening using laser shock strengthening process parameters for each zone, so that its aperture increment meets the inner aperture increment requirements of the non-uniform structure part.

10. The laser shock peening method for the inner hole of a non-uniform structural part according to claim 1, characterized in that, The laser shock peening process parameters are used to perform laser shock peening on the inner hole of the non-uniform structure part, specifically as follows: The laser shock peening process parameters of each zone of the inner hole of the non-uniform structure part are used to perform laser shock peening processing on the inner hole of the non-uniform structure part.

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