Surface treatment method and testing method for additive manufacturing titanium alloy sheet tensile sample under extreme service condition

Abstract

The invention relates to a surface treatment method and a test method for an additive manufacturing titanium alloy sheet tensile sample under an extreme service condition, and the surface treatment method comprises the following steps: (1) directly manufacturing a near-net shape titanium alloy sheet sample by adopting a selective laser melting method; and (2) the titanium alloy sheet sample is sequentially subjected to grinding, polishing and sand blasting treatment, and the titanium alloy sheet sample for testing is obtained. By adopting a combined treatment process of grinding, polishing and sand blasting, the surface roughness range required by the test can be accurately controlled, and the tensile property of the test sample can truly reflect the performance of the part while the flatness and parallelism of the test sample are ensured.

Description

TECHNICAL FIELD

[0001] The application relates to a surface treatment method for tensile testing of alloys under extreme service conditions, in particular to a surface treatment method for tensile testing of thin plates of additively manufactured titanium alloys under extreme service conditions and a testing method. BACKGROUND

[0002] In the conventional mechanical property testing of the additive manufacturing industry, the same plate is used for the furnace test bar, and the national standard / US standard is used for the room temperature tensile test. The thickness of the sample gauge section after processing is about 5-6 mm, which cannot fully reflect the true service performance of the part at the thin wall. Some technologies currently use machining methods to process the printed plate-shaped material into a thin plate tensile piece less than 2 mm. However, the problem is that the machining process is difficult to control the stress deformation in the cutting process, resulting in poor flatness and parallelism of the processed sample, which leads to inaccurate tensile results.

[0003] CN101710049A discloses a test method for tensile mechanical property testing of TiAl-based alloys, which comprises corroding the working observation surface of the sample after rough grinding, fine grinding, fine grinding and polishing. The corrosion liquid is a commonly used corrosion liquid for TiAl-based alloys, and the component volume ratio is HNO3:HF:H2O=10:5:85. A shallow corrosion state is adopted. The back surface and the edges of the sample are respectively rough ground and fine ground to 1200#-1500#. After the treatment, the inhomogeneous plastic deformation morphology of the material in the repeated stress process can be observed in detail.

[0004] CN112857936A discloses a performance testing method for heterogeneous metal composite block testing, which comprises using an electric spark wire cutting machine to cut a symmetrically distributed I-shaped sample; polishing the I-shaped sample surface with sandpaper and then polishing with a polishing machine to make the I-shaped sample surface roughness Ra≤0.8; and placing the treated I-shaped sample one into a universal testing machine, setting the Z-direction tensile working parameters, and completing the tensile test.

[0005] The above-mentioned prior art all adopts a machining method to process the tensile sample. In the machining process, high temperature may be generated, and the heat input to the material itself may be more sensitive to the thin plate material. At the same time, machining often introduces tensile stress to the surface of the tensile sample, which affects the test results.

[0006] Therefore, there is an urgent need for a new surface treatment method that can process the tensile sample of the additively manufactured titanium alloy thin plate under extreme service conditions, so as to truly reflect the tensile properties of the material. SUMMARY

[0007] To address the aforementioned technical problems, this invention provides a surface treatment method and testing method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The surface treatment method of this invention employs a combination of grinding, polishing, and sandblasting processes, which allows for precise control of the surface roughness range required for testing. This ensures the flatness and parallelism of the specimen while enabling its tensile properties to accurately reflect the performance of the part itself, and is also less expensive than machining.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a surface treatment method for additively manufactured titanium alloy sheet tensile specimens under extreme service conditions, the surface treatment method comprising:

[0010] (1) Near-net-shape titanium alloy thin plate samples were directly manufactured by laser selective melting method;

[0011] (2) The titanium alloy thin plate sample is subjected to grinding, polishing and sandblasting treatment in sequence to obtain the titanium alloy thin plate sample for testing.

[0012] This invention, through grinding, polishing, and sandblasting of titanium alloy sheets, can precisely control the surface roughness range required for testing. While ensuring the flatness and parallelism of the sample, its tensile properties can truly reflect the performance of the part itself, and the cost is lower than machining. In addition, after sandblasting the titanium alloy sheets, this invention can form a compressive stress layer on the surface of the titanium alloy sheets, thereby more accurately reflecting the material properties.

[0013] It should be noted that the near-net-shape titanium alloy sheet specimens mentioned in this invention refer to millimeter-sized titanium alloy sheet specimens that meet the test size requirements and are directly printed using laser selective melting technology, rather than specimens that are printed into block shapes and then subjected to additional processing.

[0014] As a preferred technical solution of the present invention, the length of the titanium alloy thin plate sample is 110-120mm, such as 110mm, 112mm, 114mm, 116mm, 118mm, 120mm, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0015] The width of the titanium alloy sheet sample is 10-15 mm, such as 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0016] The thickness of the titanium alloy sheet sample is 1-2 mm, such as 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0017] Preferably, the surface roughness of the titanium alloy sheet sample is 6-6.5 μm, such as 6 μm, 6.1 μm, 6.2 μm, 6.3 μm, 6.4 μm, 6.5 μm, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0018] As a preferred technical solution of the present invention, the grinding is performed using a sandblasting head; the grit of the sandblasting head is 100-120 grit, such as 100 grit, 105 grit, 110 grit, 115 grit, 120 grit, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0019] Preferably, the polishing time is 5-10 minutes, such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0020] In this invention, by controlling the grit size and time of the grinding head, it is helpful to control the surface roughness, flatness and parallelism of the titanium alloy sheet, thereby accurately reflecting the tensile properties of the sample.

[0021] As a preferred technical solution of the present invention, after grinding, the surface roughness Ra of the titanium alloy thin plate sample is ≤2.4μm, such as 2.4μm, 2.3μm, 2.2μm, 2.1μm, 2μm, 1.9μm, 1.8μm, etc., but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0022] As a preferred technical solution of the present invention, the polishing is performed using a belt sander; the mesh size of the belt sander is 200-240 mesh, such as 200 mesh, 205 mesh, 210 mesh, 215 mesh, 220 mesh, 225 mesh, 230 mesh, 235 mesh, 240 mesh, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0023] Preferably, the polishing time is 5-10 minutes, such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] In this invention, by controlling the mesh size and time of the polishing belt abrasive, it is helpful to control the surface roughness, flatness, and parallelism of the titanium alloy sheet, thereby accurately reflecting the tensile properties of the sample.

[0025] As a preferred technical solution of the present invention, after polishing, the surface roughness Ra of the titanium alloy thin plate sample is ≤0.8μm, for example 0.8μm, 0.7μm, 0.6μm, 0.5μm, 0.4μm, 0.3μm, etc., but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0026] As a preferred embodiment of the present invention, the abrasive used in the sandblasting includes white corundum.

[0027] Preferably, the abrasive has a mesh size of 200-240, such as 200 mesh, 205 mesh, 210 mesh, 215 mesh, 220 mesh, 225 mesh, 230 mesh, 235 mesh, 240 mesh, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0028] As a preferred technical solution of the present invention, the sandblasting pressure is 0.35-0.4MPa, such as 0.35MPa, 0.36MPa, 0.37MPa, 0.38MPa, 0.39MPa, 0.4MPa, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0029] Preferably, the sandblasting angle is 45° to 60°, such as 45°, 48°, 50°, 52°, 55°, 58°, 60°, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0030] In this invention, by controlling the abrasive mesh size, blasting pressure, and blasting angle, it is helpful to control the surface roughness, flatness, and parallelism of the titanium alloy sheet, thereby accurately reflecting the tensile properties of the sample.

[0031] As a preferred embodiment of the present invention, the surface treatment method includes:

[0032] (1) Near-net-shape titanium alloy thin plate samples were directly manufactured by laser selective melting method;

[0033] The length of the titanium alloy thin plate sample is 110-120 mm; the width of the titanium alloy thin plate sample is 10-15 mm; the thickness of the titanium alloy thin plate sample is 1-2 mm; and the surface roughness of the titanium alloy thin plate sample is 6-6.5 μm.

[0034] (2) The titanium alloy thin plate sample is subjected to grinding, polishing and sandblasting treatment in sequence to obtain a titanium alloy thin plate sample for testing; the grinding is performed using a sandblasting head; the mesh size of the sandblasting head is 100-120 mesh; the grinding time is 5-10 min; after grinding, the surface roughness Ra of the titanium alloy thin plate sample is ≤2.4 μm; the polishing is performed using a belt abrasive machine; the mesh size of the belt abrasive machine is 200-240 mesh; the polishing time is 5-10 min; after polishing, the surface roughness Ra of the titanium alloy thin plate sample is ≤0.8 μm; the abrasive used for sandblasting includes white corundum; the mesh size of the abrasive is 200-240 mesh; the sandblasting pressure is 0.35-0.4 MPa; the sandblasting angle is 45°~60°.

[0035] In a second aspect, the present invention provides a testing method for additively manufactured titanium alloy sheet tensile specimens under extreme service conditions, wherein the testing method performs surface quality testing and mechanical property testing on the titanium alloy sheet samples obtained by the surface treatment method described in the first aspect.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] (1) By grinding, polishing and sandblasting the titanium alloy sheet, the present invention can accurately control the surface roughness range required for testing, and ensure the flatness and parallelism of the sample while making its tensile properties truly reflect the performance of the part itself. At the same time, the cost is lower than that of machining.

[0038] (2) After the titanium alloy sheet is sandblasted, a compressive stress layer can be formed on the surface of the titanium alloy sheet, which can more realistically reflect the material properties. Detailed Implementation

[0039] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0040] Example 1

[0041] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions, the surface treatment method including:

[0042] (1) A near-net-shape titanium alloy thin plate sample with a length of 118 mm, a width of 12 mm, a thickness of 1.5 mm, and a roughness of 6.3 μm was manufactured by selective laser melting.

[0043] (2) The titanium alloy thin plate sample was ground with a 120-grit abrasive grinding head for 5 minutes, and the surface roughness of the titanium alloy thin plate sample was 2.4 μm. Then, the titanium alloy thin plate sample was polished with a 240-grit belt sander for 5 minutes, and the surface roughness of the titanium alloy thin plate sample was 0.8 μm. Then, the titanium alloy thin plate sample was sandblasted with 240-grit white corundum at a pressure of 0.35 MPa and an angle of 45° to obtain the titanium alloy thin plate sample for testing.

[0044] Example 2

[0045] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions, the surface treatment method including:

[0046] (1) A near-net-shape titanium alloy thin plate sample with a length of 110 mm, a width of 10 mm, a thickness of 1 mm, and a roughness of 6 μm was manufactured by selective laser melting.

[0047] (2) The titanium alloy thin plate sample was ground with a 110-mesh abrasive grinding head for 8 minutes, and the surface roughness of the titanium alloy thin plate sample was 2.2 μm. Then, the titanium alloy thin plate sample was polished with a 220-mesh belt sander for 8 minutes, and the surface roughness of the titanium alloy thin plate sample was 0.7 μm. Then, the titanium alloy thin plate sample was sandblasted with 220-mesh white corundum at a pressure of 0.38 MPa and an angle of 50° to obtain the titanium alloy thin plate sample for testing.

[0048] Example 3

[0049] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions, the surface treatment method including:

[0050] (1) A near-net-shape titanium alloy thin plate sample with a length of 120 mm, a width of 15 mm, a thickness of 2 mm, and a roughness of 6.5 μm was manufactured by selective laser melting.

[0051] (2) The titanium alloy thin plate sample was ground with a 100-grit abrasive grinding head for 10 minutes, and the surface roughness of the titanium alloy thin plate sample was 2.1 μm. Then, the titanium alloy thin plate sample was polished with a 200-grit belt sander for 10 minutes, and the surface roughness of the titanium alloy thin plate sample was 0.75 μm. Then, the titanium alloy thin plate sample was sandblasted with 200-grit white corundum at a pressure of 0.4 MPa and an angle of 60° to obtain the titanium alloy thin plate sample for testing.

[0052] Example 4

[0053] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that a 90-mesh abrasive grinding head is used to grind the titanium alloy sheet specimen. All other steps and conditions are the same as in Embodiment 1.

[0054] Example 5

[0055] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that a 140-grit abrasive grinding head is used to grind the titanium alloy sheet specimen. All other steps and conditions are the same as in Embodiment 1.

[0056] Example 6

[0057] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that a 180-mesh belt sander is used to polish the titanium alloy sheet specimen. All other steps and conditions are the same as in Embodiment 1.

[0058] Example 7

[0059] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that a 260-mesh belt sander is used to polish the titanium alloy sheet specimen. All other steps and conditions are the same as in Embodiment 1.

[0060] Example 8

[0061] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that 180-mesh white corundum is used to sandblast the titanium alloy sheet specimens. All other steps and conditions are the same as in Embodiment 1.

[0062] Example 9

[0063] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that 260-mesh white corundum is used to sandblast the titanium alloy sheet specimen. All other steps and conditions are the same as in Embodiment 1.

[0064] Example 10

[0065] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that the sandblasting pressure is adjusted to 0.3 MPa, while the other steps and condition parameters are the same as in Embodiment 1.

[0066] Example 11

[0067] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that the sandblasting pressure is adjusted to 0.45 MPa, while the other steps and condition parameters are the same as in Embodiment 1.

[0068] Example 12

[0069] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that the sandblasting angle is adjusted to 40°, while the other steps and condition parameters are the same as in Embodiment 1.

[0070] Example 13

[0071] This embodiment provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Embodiment 1 is that the sandblasting angle is adjusted to 70°, while the other steps and condition parameters are the same as in Embodiment 1.

[0072] Comparative Example 1

[0073] This comparative example provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Example 1 is that sandblasting is not performed, while the other steps and condition parameters are the same as in Example 1.

[0074] Comparative Example 2

[0075] This comparative example provides a surface treatment method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. The only difference from Example 1 is that polishing is not performed. After grinding the titanium alloy sheet specimen, it is directly subjected to sandblasting. All other steps and conditions are the same as in Example 1.

[0076] Performance testing

[0077] The titanium alloy sheet samples obtained in Examples 1-13 and Comparative Examples 1-2 were subjected to surface quality and mechanical property tests. The surface quality test included three-coordinate dimensional testing to test the straightness and flatness of the sample. The mechanical property test included tensile testing. The tensile test was conducted in accordance with GB / T 228 standard, and the yield strength, tensile strength and elongation were recorded. The test results are shown in Table 1.

[0078] Table 1

[0079]

[0080]

[0081] The test results show that:

[0082] (1) As can be seen from Examples 1-3, by grinding, polishing and sandblasting the titanium alloy sheet, the present invention can accurately control the surface roughness range required for testing, and ensure the flatness and parallelism of the sample while making its tensile properties truly reflect the performance of the part itself.

[0083] (2) By comparing Example 1 and Examples 4-13, it can be seen that the mesh size of the abrasive, as well as the sandblasting pressure and sandblasting angle, in the grinding, polishing and sandblasting processes of the present invention will affect the straightness and parallelism of the titanium alloy thin plate sample, and thus affect its tensile properties test.

[0084] (3) As can be seen from Example 1 and Comparative Examples 1-2, no sandblasting was performed in Comparative Example 1, which introduced tensile stress to the surface of the tensile specimen during the machining process, affecting the tensile performance test results; no polishing was performed in Comparative Example 2, which affected the surface roughness of the titanium alloy thin plate sample, and thus affected its straightness, flatness and tensile performance test.

[0085] In summary, this invention provides a surface treatment method and testing method for additive manufacturing of titanium alloy sheet tensile specimens under extreme service conditions. By grinding, polishing, and sandblasting the titanium alloy sheet, this invention can precisely control the surface roughness range required for testing, ensuring the flatness and parallelism of the specimen while enabling its tensile properties to truly reflect the performance of the part itself, and at a lower cost than machining. Furthermore, after sandblasting the titanium alloy sheet, this invention can form a compressive stress layer on the surface of the titanium alloy sheet, thereby more accurately reflecting the material properties.

[0086] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for surface treatment of additively manufactured titanium alloy sheet tensile specimens under extreme service conditions, characterized by, The surface treatment method comprises: (1) using a laser selective melting method to directly manufacture a near-net-shape titanium alloy thin plate sample; (2) sequentially performing grinding, polishing and sand blasting treatment on the titanium alloy thin plate sample to obtain a titanium alloy thin plate sample for testing.

2. The surface treatment method according to claim 1, characterized by, The length of the titanium alloy thin plate sample is 110-120 mm; the width of the titanium alloy thin plate sample is 10-15 mm; the thickness of the titanium alloy thin plate sample is 1-2 mm; and the surface roughness of the titanium alloy thin plate sample is 6-6.5 μm. Preferably, the surface roughness of the titanium alloy thin plate sample is 6-6.5 μm.

3. The surface treatment method according to claim 1 or 2, characterized by, The grinding is performed using a sandstone grinding head; and the mesh number of the sandstone grinding head is 100-120 mesh. Preferably, the grinding time is 5-10 min.

4. The surface treatment method according to any one of claims 1 to 3, characterized by, After the grinding, the surface roughness of the titanium alloy thin plate sample is Ra≤2.4 μm.

5. The surface treatment method according to any one of claims 1 to 4, characterized in that, The polishing is performed using a sand belt machine; and the mesh number of the sand belt machine is 200-240 mesh. Preferably, the polishing time is 5-10 min.

6. The surface treatment method according to any one of claims 1 to 5, characterized by, After the polishing, the surface roughness of the titanium alloy thin plate sample is Ra≤0.8 μm.

7. The surface treatment method according to any one of claims 1 to 6, characterized by, The abrasive of the sand blasting comprises any one of white corundum, brown corundum or glass beads. Preferably, the mesh number of the abrasive is 200-240 mesh.

8. The surface treatment method according to any one of claims 1 to 7, characterized by, The pressure of the sand blasting is 0.35-0.4 MPa. Preferably, the angle of the sand blasting is 45°-60°.

9. The surface treatment method according to any one of claims 1 to 8, characterized by, The surface treatment method comprises: (1) using a laser selective melting method to directly manufacture a near-net-shape titanium alloy thin plate sample; The length of the titanium alloy thin plate sample is 110-120 mm; the width of the titanium alloy thin plate sample is 10-15 mm; the thickness of the titanium alloy thin plate sample is 1-2 mm; and the surface roughness of the titanium alloy thin plate sample is 6-6.5 μm. (2) sequentially performing grinding, polishing and sand blasting treatment on the titanium alloy thin plate sample to obtain a titanium alloy thin plate sample for testing; the grinding is performed using a sandstone grinding head; the mesh number of the sandstone grinding head is 100-120 mesh; the grinding time is 5-10 min; after the grinding, the surface roughness of the titanium alloy thin plate sample is Ra≤2.4 μm; the polishing is performed using a sand belt machine; the mesh number of the sand belt machine is 200-240 mesh; the polishing time is 5-10 min; after the polishing, the surface roughness of the titanium alloy thin plate sample is Ra≤0.8 μm; the abrasive of the sand blasting comprises any one of white corundum, brown corundum or glass beads; the mesh number of the abrasive is 200-240 mesh; the pressure of the sand blasting is 0.35-0.4 MPa; and the angle of the sand blasting is 45°-60°.

10. A method of testing additively manufactured titanium alloy sheet tensile specimens under extreme service conditions, characterized by, The test method is used to perform surface quality testing and mechanical property testing on the titanium alloy thin plate sample obtained by the surface treatment method according to any one of claims 1-9.

Images