Additive manufacturing metal piece and surface composite strengthening method and tool thereof

Abstract

The application provides a metal part prepared by additive manufacturing and a surface composite strengthening method and tool thereof. The method comprises the following steps: S1, preparing a metal part (1) and a plurality of test pieces (2) by additive manufacturing; S2, initially selecting 5-10 groups of laser shock peening and shot peening process parameter combinations to perform laser shock and mechanical shot peening composite strengthening on the test pieces (2); S3, measuring the surface porosity, surface morphology and surface residual stress of the test pieces (2) after the composite strengthening, and screening out optimal process parameters; and S4, taking the metal part (1) and performing laser shock-mechanical shot peening composite strengthening on the metal part (1) according to the optimal process parameters. The application proposes a laser shock-mechanical shot peening composite strengthening method for the metal part prepared by additive manufacturing, which can significantly improve the surface layer performance of the metal part prepared by additive manufacturing; the process is simple to implement, and will not cause excessive deformation to the metal part prepared by additive manufacturing; and the surface after the strengthening is the final surface, and no other treatment is needed.

Description

Technical Field

[0001] This invention belongs to the field of metal processing, specifically relating to an additive manufacturing metal part and its surface composite strengthening method and tooling. Background Technology

[0002] Additive manufacturing can produce complex structures that are difficult to achieve with traditional subtractive manufacturing, enabling the integrated manufacturing of complex assemblies. However, surface defects that may exist during the manufacturing process, such as porosity, residual tensile stress, and microcracks, affect its fatigue performance and limit its use in load-bearing components to some extent. Surface strengthening technology has proven its great potential in fatigue-resistant manufacturing, but traditional single-process surface strengthening techniques have little effect on additive manufacturing materials. Therefore, there is an urgent need to develop a composite strengthening technology suitable for additive manufacturing materials to meet the current demands for high performance, long life, and high reliability in high-end equipment components.

[0003] Patent CN202411834401.7 discloses a method for improving the fatigue performance of additively manufactured titanium alloys. This method improves the fatigue performance of additively manufactured titanium alloys through a comprehensive approach involving residual stress elimination and surface strengthening. Patent CN202510257023.9 ​​discloses a shot peening method for enhancing the mechanical properties of laser-additively manufactured titanium-based composite materials. This treatment introduces residual compressive stress by bombarding the metal surface with small particles, causing plastic deformation of the surface structure and improving the mechanical properties of the laser-additively manufactured titanium-based composite materials.

[0004] Combining laser shock and mechanical shot peening as a combined strengthening method can lead to quality problems such as excessive deformation due to differences in the combined parameters compared to the individual methods.

[0005] The above methods for surface strengthening of additive manufacturing materials still have the following shortcomings: ① The steps are rather complicated, making it difficult to quickly strengthen the material surface; ② The strengthening effect on surface microstructure defects is insufficient; ③ The reinforcement layer is not deep enough or the surface roughness is poor. Summary of the Invention

[0006] The technical problem of this invention is: ① The steps are rather complicated, making it difficult to quickly strengthen the material surface; ② The strengthening effect on surface microstructure defects is insufficient; ③ The reinforcement layer is not deep enough or the surface roughness is poor.

[0007] The purpose of this invention is: This invention aims to address the problem that existing single-process strengthening processes have minimal strengthening effects on the surface of additively manufactured metal parts, which may be caused by surface defects during the manufacturing process.

[0008] The technical solution of this invention is: In a first aspect, the present invention proposes a method for surface composite strengthening of additively manufactured metal parts, comprising the following steps: 1. While obtaining the required metal part blank through additive manufacturing, 5-10 test blanks of 20mm×20mm×15mm are also additively manufactured.

[0009] 2. Take the metal blank obtained by additive manufacturing, perform pretreatment such as milling and grinding on it, and form it into a metal part (1); take the test piece blank obtained by additive manufacturing, and form it into a test piece (2) according to the same pretreatment process as the metal part (1).

[0010] 3. Select 5-10 sets of laser shock peening and shot peening process parameter combinations and perform laser shock peening-mechanical shot peening composite strengthening on the test piece (2), specifically: 1) Fix the test piece (2) on the laser shock worktable, lay the constraint layer and the protective layer, and compile the operating program of the laser shock worktable and the laser shock head.

[0011] 2) Run the prepared laser shock strengthening program to uniformly strengthen the test piece (2) with a spot diameter of 2~10mm, a laser pulse width of 10~20ns, a laser power density of 2~10GW / mm2, and an overlap rate of 30%~70%.

[0012] 3) Take the test piece (2) after laser shock, apply a protective layer to the areas other than the strengthening area (201), install it on the fixture of the shot peening equipment, and compile the shot peening program.

[0013] 4) Run the prepared mechanical shot peening strengthening program to mechanically peen the test piece (2). The selected shot is generally ceramic shot or cast steel shot. The shot diameter is generally 0.05mm-0.50mm, the shot flow rate is 0.2kg / min-1.5kg / min, the spray pressure is 0.05MPa-0.20MPa, and the coverage rate is 100%~400%.

[0014] 5) The laser shock strengthening constraint layer is black tape or aluminum foil, the laser shock strengthening protective layer is plasma water film, and the shot peening strengthening protective layer is black tape.

[0015] 4. Measure the surface porosity, surface morphology and surface residual stress of the composite-strengthened specimen (2) and select the optimal process parameters.

[0016] 5. Take the metal part (1) and perform laser shock peening-mechanical shot peening composite strengthening on it according to the preferred process parameters, as follows: 1) Fix the metal part (1) onto the laser shock worktable (3), lay the constraint layer (4) and the protective layer (5), and compile the operating program of the laser shock worktable (3) and the laser shock head (6).

[0017] 2) Run the prepared laser shock strengthening program to uniformly laser strengthen the metal part (1).

[0018] 3) Take the metal part (1) after laser shock strengthening and apply a protective layer (7) to the non-spraying area (102) outside the sprayable area (101).

[0019] 4) Take the protected metal part (1), install it on the fixture (8) of the shot peening equipment, compile the shot peening program, and control the operation of the spray gun 9 and the shot peening parameters.

[0020] 5) Run the prepared mechanical shot peening strengthening program to mechanically peen the metal part (1).

[0021] 6) Remove the protective layer (7) and clean it with a high-pressure air gun and anhydrous ethanol to ensure that there are no bullets or tape residues on the surface of the metal parts (1).

[0022] 7) The constraint layer (4) is black tape or aluminum foil, the protective layer (5) is plasma water film, and the protective layer (7) is black tape.

[0023] 8) The parameters involved in laser shock peening are laser pulse width, laser power density, and overlap ratio, which are determined by step 4.

[0024] 9) The mechanical shot peening strengthening design parameters are shot medium, shot diameter, shot flow rate and injection pressure, which are determined by step 4.

[0025] Secondly, this invention proposes a surface composite strengthening tooling for additively manufactured metal parts, the tooling comprising: Metal parts (1), test piece (2), laser impact worktable (3), constraint layer (4), laser protective layer (5), laser impact head (6), shot peening protective layer (7), fixture (8); The metal part (1) is provided with a sprayable area (101) and a no-spray area (102). The test piece (2) has a region to be reinforced (201) and a region not to be reinforced (202). Metal parts (1) are fixed on the laser shock worktable (3), a constraint layer (4) and a protective layer (5) are laid, and the operating program of the laser shock worktable (3) and the laser shock head (6) is programmed. Run the prepared laser shock strengthening program to uniformly laser strengthen the metal part (1); Take the metal part (1) after laser shock strengthening and apply a protective layer (7) to the no-spray area (102); take the metal part (1) after protection and install it on the fixture (8) of the shot peening equipment, compile the shot peening program, and control the operation of the spray gun (9) and the shot peening parameters. Run the prepared mechanical shot peening strengthening program to mechanically peen the metal part (1).

[0026] Thirdly, the present invention proposes an additive manufacturing metal part, which is prepared using the above-described method.

[0027] The advantages and beneficial effects of this invention are: This invention proposes an optimized laser shock peening-mechanical shot peening composite strengthening method for additively manufactured metal parts (the traditional method directly combines two methods, which can cause excessive deformation and other quality problems due to the difference between the combined parameters and the parameters of the individual methods). This method can significantly improve the surface performance of additively manufactured metal parts. The process is simple to implement and will not cause excessive deformation to the additively manufactured metal parts. The strengthened surface is the final surface and no further treatment is required. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 Additive manufacturing test pieces and additively manufactured metal parts to be reinforced; Figure 2 Surface morphology after strengthening; Figure 3 Surface residual stress test results; Figure 4 Schematic diagram of laser shock peening; Figure 5 Schematic diagram of shot peening.

[0030] Figure label: Metal parts (1), test piece (2), laser impact worktable (3), constraint layer (4), laser protective layer (5), laser impact head (6), shot peening protective layer (7), fixture (8); Sprayable area (101), no-spray area (102, not shown in the figure); Area to be reinforced (201), unreinforced area (202, not shown in the figure). Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] 1. The part to be strengthened in this example is an additively manufactured titanium alloy flat fatigue part. While obtaining the required titanium alloy part blank through additive manufacturing, seven 20mm×20mm×15mm titanium alloy test blanks are also additively manufactured.

[0034] 2. Take the titanium alloy blank obtained from additive manufacturing, and perform pretreatment such as milling and grinding on it to form a metal part (1); take the test piece blank obtained from additive manufacturing, and perform the same pretreatment process as the metal part (1) to form a test piece (2), such as... Figure 1 As shown.

[0035] 3. Seven combinations of laser shock peening and shot peening process parameters were initially selected, as shown in Table 1. The test piece (2) was subjected to laser shock peening-mechanical shot peening composite strengthening, specifically as follows: Table 1. Combination of laser shock peening and shot peening process parameters in Example 1

[0036] 1) Fix the test piece (2) on the laser shock worktable, lay the constraint layer and the protective layer, and compile the operating program of the laser shock worktable and the laser shock head.

[0037] 2) Run the prepared laser shock strengthening program to uniformly strengthen the surface of the area (201) to be strengthened on the test piece (2). The laser shock parameters are shown in Table 1.

[0038] 3) Take the test piece (2) after laser impact, arrange the protective layer on the no-penetration area, and install it on the fixture of the shot peening equipment, and compile the shot peening program.

[0039] 4) Run the prepared mechanical shot peening strengthening program to perform mechanical shot peening strengthening on the test piece (2). The mechanical shot peening parameters are shown in Table 1.

[0040] 5) The laser shock strengthening constraint layer is black tape, the laser shock strengthening protective layer is plasma water film, and the shot peening strengthening protective layer is black tape.

[0041] 4. To screen and optimize process parameters, the surface porosity, surface morphology, and surface residual stress of the 6 groups of strengthened specimens (2) were measured within 100 μm. The surface porosity test results are shown in Table 2, and the surface morphology test results are shown in Table 3. Figure 2 As shown, the surface residual stress test results are as follows: Figure 3 As shown in the figure, analysis revealed that the sixth group of process parameters exhibited the lowest surface porosity, moderate surface roughness, and the highest surface residual compressive stress, making it the preferred process parameter.

[0042] Table 2. Surface porosity test results

[0043] 5. Take the metal part (1) and perform laser shock peening-mechanical shot peening composite strengthening on it according to the preferred process parameters, as follows: 1) Fix the metal part (1) onto the laser shock stage (3), lay the constraint layer (4) and the protective layer (5), and program the operation of the laser shock stage (3) and the laser shock head (6), as follows: Figure 4 As shown.

[0044] 2) Run the prepared laser shock strengthening program to uniformly laser strengthen the metal part (1).

[0045] 3) Take the metal part (1) after laser shock strengthening and apply a protective layer (7) to the no-spray area.

[0046] 4) Take the protected metal part (1) and install it on the fixture (8) of the shot peening equipment. Compile the shot peening program for the spray gun 9, as follows: Figure 5 As shown.

[0047] 5) Run the prepared mechanical shot peening strengthening program to mechanically peen the metal part (1).

[0048] 6) Remove the protective layer (7) and clean it with a high-pressure air gun and anhydrous ethanol to ensure that there are no bullets or tape residues on the surface of the metal parts (1).

[0049] 7) The constraint layer (4) is black tape, the protective layer (5) is plasma water film, and the protective film 8 is black tape.

[0050] 8) The parameters involved in the laser shock enhancement are the spot diameter, laser pulse width, laser power density and overlap rate, which are determined by step 4. Specifically, the spot diameter is 2 mm, the laser pulse width is 10 ns, the laser power density is 2 GW / mm2, and the overlap rate is 50%.

[0051] 9) The mechanical shot peening strengthening design parameters are shot medium, shot diameter, shot flow rate and injection pressure, which are determined by step 4. Specifically, the shot medium is ceramic shot, the shot diameter is 300μm, the shot flow rate is 1.2kg / min and the injection pressure is 0.15 MPa.

[0052] Compared with the prior art, the present invention has the following advantages: The present invention proposes a laser shock-mechanical shot peening composite strengthening method for additively manufactured metal parts, which can significantly improve the surface properties of additively manufactured metal parts; the process is simple to implement and will not cause excessive deformation to the additively manufactured metal parts, and the surface after strengthening is the final surface, without the need for other treatments.

[0053] It should be noted that the above process operations can be combined to varying degrees. For the sake of brevity, the implementation methods of various combinations will not be elaborated here. Those skilled in the art can flexibly adjust the order of the above operation steps or flexibly combine the above steps according to actual needs.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A method for surface composite strengthening of additively manufactured metal parts, characterized in that, Includes the following steps: S1, metal parts (1) and multiple test pieces (2) are prepared by additive manufacturing. S2, initially select 5-10 sets of laser shock strengthening and shot peening process parameter combinations, and perform laser shock and mechanical shot peening composite strengthening on the test piece (2); S3, the surface porosity, surface morphology and surface residual stress of the composite-strengthened specimen (2) are measured to screen out the preferred process parameters; S4, take the metal part (1) and perform laser shock-mechanical shot peening composite strengthening on it according to the preferred process parameters.

2. The method according to claim 1, characterized in that, in: Step S2 includes: S21, a constraint layer (4) and a laser protection layer (5) are laid on the reinforcement area (201) of the test piece (2). S22, uniform laser strengthening is performed on the strengthening area (201) of the test piece (2); S23, take the test piece (2) after laser shock, and apply a shot peening protective layer (7) to the non-strengthened area (202). S24, mechanical shot peening is performed on the reinforced area (201) of the test piece (2).

3. The method according to claim 1, characterized in that, in: In step S22: The parameters involved in laser shock peening are: The diameter of the light spot is 2~10mm; The laser pulse width is 10~20ns; The laser power density is 2~10GW / mm2; The overlap rate is 30%~70%.

4. The method according to claim 1, characterized in that, in: In step S22: The parameters involved in laser shock peening are: The spot diameter is 2mm; Laser pulse width 10ns; Laser power density 2GW / mm2; Overlap rate: 50%.

5. The method according to claim 1, characterized in that, in: In step S24: The mechanical shot peening strengthening design parameters are: The diameter of the projectile is 0.05mm-0.50mm; The projectile flow rate is 0.2 kg / min - 1.5 kg / min; The injection pressure is 0.05 MPa - 0.20 MPa; The coverage rate is 100% to 400%.

6. The method according to claim 1, characterized in that, in: In step S24: The mechanical shot peening strengthening design parameters are: The projectile diameter is 300 μm; The projectile flow rate is 1.2 kg / min; The injection pressure is 0.15 MPa.

7. The method according to claim 1, characterized in that, in: Step S1 includes: S11, while obtaining the required metal part blank through additive manufacturing, 5-10 test blanks of 20mm×20mm×15mm are additively manufactured; S12, take the metal blank obtained by additive manufacturing, perform pretreatment such as milling and grinding on it, and form it into a metal part (1). S13, take the sample blank obtained by additive manufacturing and form it into a sample (2) according to the same pretreatment process as the metal part (1).

8. The method according to any one of claims 1-7, characterized in that, in: In step S24: The selected projectiles are ceramic or cast steel. The constraint layer (4) is black tape or aluminum foil; The laser protective layer (5) is a plasma water film; The shot peening reinforced protective layer (7) is black tape.

9. A composite reinforcement tooling for the surface of additively manufactured metal parts, characterized in that, An additively manufactured metal part is prepared using a surface composite strengthening method for additively manufactured metal parts according to any one of claims 1-8, wherein the tooling includes: Metal parts (1), test piece (2), laser impact worktable (3), constraint layer (4), laser protective layer (5), laser impact head (6), shot peening protective layer (7), fixture (8); The metal part (1) is provided with a sprayable area (101) and a no-spray area (102). The test piece (2) has a region to be reinforced (201) and a region not to be reinforced (202). Metal parts (1) are fixed on the laser shock worktable (3), a constraint layer (4) and a protective layer (5) are laid, and the operating program of the laser shock worktable (3) and the laser shock head (6) is programmed. Run the prepared laser shock strengthening program to uniformly laser strengthen the metal part (1); Take the metal part (1) after laser shock strengthening and apply a protective layer (7) to the no-spray area (102); take the metal part (1) after protection and install it on the fixture (8) of the shot peening equipment, compile the shot peening program, and control the operation of the spray gun (9) and the shot peening parameters. Run the prepared mechanical shot peening strengthening program to mechanically peen the metal part (1).

10. An additively manufactured metal part, characterized in that, Prepared using any one of the methods described in claims 1-8.

Images