Processing method for nickel plating of aviation titanium alloy part

Abstract

The invention discloses a machining method for nickel plating of aviation titanium alloy parts, and belongs to the technical field of part machining. The method comprises the following steps: roughly machining a titanium alloy part raw material; the stress of the part is eliminated through vacuum heat treatment or natural aging; the titanium alloy part is subjected to semi-finish machining; the stress of the part is eliminated through vacuum heat treatment or natural aging; the titanium alloy part is machined to a state required by a drawing; performing corresponding flaw detection on the titanium alloy part according to drawing requirements; the titanium alloy part is subjected to chemical nickel plating according to drawing requirements; the titanium alloy part is manually polished and repaired; the titanium alloy part is subjected to size inspection, and it is guaranteed that the titanium alloy part meets the drawing requirement. Under the condition that the material performance of the part is guaranteed, internal stress generated by machining is eliminated, stress deformation in the nickel plating process is reduced, and it is guaranteed that the size is qualified after nickel plating; and the machining mode of polishing and repairing the nickel plating layer is defined, and the dimensional precision and performance requirements of the part after nickel plating are ensured.

Description

Technical Field

[0001] The invention relates to a nickel-plated processing method for aviation titanium alloy parts, belonging to the technical field of parts processing. Background Art

[0002] In the field of aero-engines, with the continuous development of technology, titanium alloy parts have been widely used in multiple components of aero-engines due to their remarkable characteristics such as low density, high strength and corrosion resistance, and are gradually replacing traditional carburizing and nitriding steel parts.

[0003] In order to further improve the corrosion resistance of titanium alloy parts and enhance their hardness and wear resistance, the titanium alloy nickel plating process came into being. Due to its high hardness and wear resistance, the nickel plating layer is particularly suitable for the parts that match the bearings in aircraft engines, which can effectively extend the service life of the parts.

[0004] Since parts need to maintain a high degree of stability during machining to avoid the nickel plating layer from falling off due to deformation and other factors, control during the machining process is particularly important. At the same time, the high hardness and corrosion resistance of the nickel layer also lead to its relatively poor processing characteristics. Improper machining can easily cause the nickel layer to fall off, thus affecting the performance and service life of the parts.

[0005] The existing titanium alloy nickel-plated parts processing steps usually include rough machining, semi-finishing, finishing, nickel plating, nickel layer processing and dimensional inspection of titanium alloy parts. However, there are obvious technical difficulties in this processing process, that is, the parts are prone to deformation after nickel plating, which makes it difficult to accurately control the nickel layer thickness and part size within the range required by the part drawing, thus failing to meet actual use requirements. Summary of the invention

[0006] In order to solve the problems existing in the background technology, the present invention provides a processing method for nickel plating aviation titanium alloy parts.

[0007] To achieve the above object, the present invention adopts the following technical scheme: a method for processing nickel plating of aviation titanium alloy parts, the method comprising the following steps:

[0008] S1: Rough machining: Rough machining of the raw materials of titanium alloy parts, leaving a machining allowance of 0.5mm-1mm;

[0009] S2: Stress relief: Eliminate stress on parts through vacuum heat treatment or natural aging;

[0010] The heat treatment temperature in S2 is 700-800°C, the holding time is 2-4 hours, and the vacuum degree is ≤1×10 -2 Pa.

[0011] S3: Semi-finishing: Semi-finishing the titanium alloy parts obtained in S2, leaving a machining allowance of 0.2mm-0.5mm;

[0012] S4: Repeat S2 to perform secondary stress relief on the titanium alloy part obtained in S3:

[0013] S5: Finishing: Process the titanium alloy parts obtained in S4 to the state required by the drawing;

[0014] S6: Flaw detection: Perform corresponding flaw detection on the titanium alloy parts machined in S5 according to the requirements of the drawings;

[0015] The flaw detection described in S6 includes fluorescent penetrant testing and / or X-ray testing, and the qualification criteria are: the length of cracks and pores is ≤0.1mm, the total number of defects in a single part is ≤3, and the proportion of coating detachment area is ≤5%.

[0016] S7: Nickel plating: chemically nickel plating the titanium alloy parts obtained in S6 according to the requirements of the drawings;

[0017] The S7 comprises the following steps:

[0018] S701: The surfaces of the inner hole and outer diameter of the titanium alloy parts are pretreated by sand blasting and weak acid activation. The pretreatment amount is the same as the coating thickness, so that the surface size of the titanium alloy parts meets the pre-plating size;

[0019] The sand blasting in S701 uses alumina sand with a particle size of 120-180 mesh, an air pressure of 0.3-0.5 MPa, a sand blasting angle of 45-60°, and a surface roughness Ra≤3.2μm after sand blasting.

[0020] The weak acid activation in S701 uses a nitric acid solution with a volume concentration of 5-10%, and the activation time is 30-60s.

[0021] S702: The pre-plating size is the maximum size on the drawing minus 0.005mm, and the minimum size plus 0.005mm;

[0022] S703: Plating titanium alloy parts.

[0023] S8: Polishing: Manually polish the titanium alloy parts obtained in S7;

[0024] The S8 comprises the following steps:

[0025] S801: Observe whether there is a gray-black matrix on the surface of the titanium alloy parts. If so, it means that the nickel layer has fallen off and the product is unqualified; otherwise, the titanium alloy parts with no nickel layer falling off are subjected to S802;

[0026] S801 The surface of the titanium alloy parts described in the experiment is observed with the assistance of an endoscope to determine the nickel layer shedding condition. Parts with a gray-black matrix area exceeding 5% are deemed scrapped.

[0027] S802: Measure the coating thickness of titanium alloy parts whose nickel layer has not fallen off, and classify the titanium alloy parts with qualified coating thickness into Group A, the titanium alloy parts with coating thickness exceeding the tolerance within 0.005mm into Group B, and the titanium alloy parts with coating thickness exceeding the tolerance by more than 0.005mm and requiring multiple polishing and repairing into Group C;

[0028] S803: Polish the titanium alloy parts of group A to qualified standard using diamond sandpaper with grit of 800-1200 mesh;

[0029] S804: Use an abrasive cloth roll with a rotation speed of 200-300rpm and a removal rate of ≤0.001mm / time to evenly remove and polish the titanium alloy parts in group B to a qualified size, and then proceed to S803;

[0030] S805: For the titanium alloy parts of group C, use an abrasive cloth roll with a rotation speed of 200-300rpm and a removal rate of ≤0.001mm / time to evenly polish them for one circle, then cool them to 20±5℃. After cooling time ≥15min, repeat polishing again until the qualified size is reached, and then proceed to S803.

[0031] S9: Final inspection: Perform dimensional inspection on the titanium alloy parts obtained in S8 to ensure that they meet the requirements of the drawings.

[0032] The S9 comprises the following steps:

[0033] S901: Dimension inspection: Use a three-coordinate measuring machine to verify the dimensional tolerance, with an allowable deviation of ±0.005mm;

[0034] S902: Coating inspection: The nickel layer thickness is measured by X-ray fluorescence spectrometry, and the uniformity deviation is ≤±0.003mm.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention adds two vacuum heat treatment steps to eliminate stress, eliminates the internal stress generated by machining while ensuring the material performance of the parts, reduces the stress deformation in the nickel plating process, and ensures that the dimensions after nickel plating are qualified; at the same time, the machining dimensions of the shrunken nickel-plated parts are tested and calculated, and only local polishing is performed after nickel plating to reduce deformation, clarifies the processing method of polishing the nickel-plated layer, ensures the dimensional accuracy and performance requirements of the parts after nickel plating, improves the yield and performance of titanium alloy nickel-plated products, and meets the use needs in high-requirement fields such as aircraft engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1is a flow chart of the present invention;

[0038] Figure 2 This is a schematic diagram of the corresponding values ​​of the dimensions of the inner hole of a titanium alloy part before and after nickel plating;

[0039] Figure 3 This is a schematic diagram of the corresponding values ​​of the outer diameter dimensions of titanium alloy parts before and after nickel plating. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] A method for processing nickel plating of aviation titanium alloy parts, the method comprising the following steps:

[0042] S1: Rough machining: Rough machining of raw materials (bars, forgings, castings) of titanium alloy parts to remove excess parts; the machining allowance varies according to parts of different structural sizes, and generally 0.5mm-1mm machining allowance is reserved;

[0043] S2: Stress elimination: Eliminate the stress of parts through vacuum heat treatment or natural aging to control the deformation of parts;

[0044] The heat treatment temperature in S2 is 700-800°C, the holding time is 2-4 hours, and the vacuum degree is ≤1×10 -2 Pa.

[0045] S3: Semi-finishing: Semi-finishing the titanium alloy parts obtained in S2. The machining allowance varies according to the parts with different structural sizes. Generally, 0.2mm-0.5mm machining allowance is reserved.

[0046] S4: Repeat S2 to perform secondary stress relief on the titanium alloy part obtained in S3:

[0047] S5: Finishing: Process the titanium alloy parts obtained in S4 to the state required by the drawing;

[0048] S6: Flaw detection: Perform corresponding flaw detection on the titanium alloy parts machined in S5 according to the requirements of the drawings;

[0049] The flaw detection described in S6 includes fluorescent penetrant testing (FPI) and / or X-ray testing, and the qualification criteria are: the length of cracks and pores is ≤0.1mm, the total number of defects in a single part is ≤3, and the proportion of coating detachment area is ≤5%.

[0050] S7: Nickel plating: chemically nickel plating the titanium alloy parts obtained in S6 according to the requirements of the drawings;

[0051] The S7 comprises the following steps:

[0052] S701: The surfaces of the inner hole and outer diameter of the titanium alloy parts are pretreated by sand blasting and weak acid activation. The pretreatment amount is the same as the coating thickness, and the overall removal amount is basically maintained at 0.008mm-0.012mm, so that the surface size of the titanium alloy parts meets the pre-plating size;

[0053] The sand blasting in S701 uses alumina sand with a particle size of 120-180 mesh, an air pressure of 0.3-0.5 MPa, a sand blasting angle of 45-60°, and a surface roughness Ra≤3.2μm after sand blasting.

[0054] The weak acid activation in S701 uses a nitric acid solution with a volume concentration of 5-10%, and the activation time is 30-60s.

[0055] S702: The pre-plating size is the maximum size on the drawing minus 0.005mm, and the minimum size plus 0.005mm;

[0056] S703: Plating titanium alloy parts.

[0057] S8: Polishing: Manually polish the titanium alloy parts obtained in S7;

[0058] The S8 comprises the following steps:

[0059] S801: Observe whether there is a gray-black matrix on the surface of the titanium alloy parts. If so, it means that the nickel layer has fallen off and the product is unqualified; otherwise, the titanium alloy parts with no nickel layer falling off are subjected to S802;

[0060] S801 The surface of the titanium alloy parts described in the experiment is observed with the assistance of an endoscope to determine the nickel layer shedding condition. Parts with a gray-black matrix area exceeding 5% are deemed scrapped.

[0061] S802: Measure the coating thickness of titanium alloy parts whose nickel layer has not fallen off, and classify the titanium alloy parts with qualified coating thickness into Group A, the titanium alloy parts with coating thickness exceeding the tolerance within 0.005mm into Group B, and the titanium alloy parts with coating thickness exceeding the tolerance by more than 0.005mm and requiring multiple polishing and repairing into Group C;

[0062] S803: Polish the titanium alloy parts of group A to qualified standard using diamond sandpaper with grit of 800-1200 mesh;

[0063] S804: Use an abrasive cloth roll with a rotation speed of 200-300rpm and a removal rate of ≤0.001mm / time to evenly remove and polish the titanium alloy parts in group B to a qualified size, and then proceed to S803;

[0064] S805: For the titanium alloy parts of group C, use an emery cloth roll with a rotation speed of 200-300rpm and a removal rate of ≤0.001mm / time to polish evenly for one circle, then cool to 20±5℃. After cooling time ≥15min, repeat polishing again until the qualified size is reached to prevent the nickel layer from falling off due to overheating, and then proceed to S803.

[0065] S9: Final inspection: Perform dimensional inspection on the titanium alloy parts obtained in S8 to ensure that they meet the requirements of the drawings.

[0066] The S9 comprises the following steps:

[0067] S901: Dimension inspection: Use a three-coordinate measuring machine to verify the dimensional tolerance, with an allowable deviation of ±0.005mm;

[0068] S902: Coating inspection: The nickel layer thickness is measured by X-ray fluorescence spectrometry (XRF), and the uniformity deviation is ≤±0.003mm.

[0069] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0070] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for nickel plating aviation titanium alloy parts, characterized in that: The method comprises the following steps: S1: Rough machining: Rough machining of the raw materials of titanium alloy parts, leaving a machining allowance of 0.5mm-1mm; S2: Stress relief: Eliminate stress on parts through vacuum heat treatment or natural aging; S3: Semi-finishing: Semi-finishing the titanium alloy parts obtained in S2, leaving a machining allowance of 0.2mm-0.5mm; S4: Repeat S2 to perform secondary stress relief on the titanium alloy part obtained in S3: S5: Finishing: Process the titanium alloy parts obtained in S4 to the state required by the drawing; S6: Flaw detection: Perform corresponding flaw detection on the titanium alloy parts machined in S5 according to the requirements of the drawings; S7: Nickel plating: chemically nickel plating the titanium alloy parts obtained in S6 according to the requirements of the drawings; S8: Polishing: Manually polish the titanium alloy parts obtained in S7; S9: Final inspection: Perform dimensional inspection on the titanium alloy parts obtained in S8 to ensure that they meet the requirements of the drawings.

2. The method for nickel plating aviation titanium alloy parts according to claim 1, characterized in that: The heat treatment temperature in S2 is 700-800°C, the holding time is 2-4 hours, and the vacuum degree is ≤1×10 -2 Pa.

3. The method for nickel plating aviation titanium alloy parts according to claim 1, characterized in that: The flaw detection described in S6 includes fluorescent penetrant testing and / or X-ray testing, and the qualification criteria are: the length of cracks and pores is ≤0.1mm, the total number of defects in a single part is ≤3, and the proportion of coating detachment area is ≤5%.

4. A method for nickel plating aviation titanium alloy parts according to claim 2 or 3, characterized in that: The S7 comprises the following steps: S701: The surfaces of the inner hole and outer diameter of the titanium alloy parts are pretreated by sand blasting and weak acid activation. The pretreatment amount is the same as the coating thickness, so that the surface size of the titanium alloy parts meets the pre-plating size; S702: The pre-plating size is the maximum size on the drawing minus 0.005mm, and the minimum size plus 0.005mm; S703: Plating titanium alloy parts.

5. The method for nickel plating aviation titanium alloy parts according to claim 4, characterized in that: The sand blasting in S701 uses alumina sand with a particle size of 120-180 mesh, an air pressure of 0.3-0.5 MPa, a sand blasting angle of 45-60°, and a surface roughness Ra≤3.2μm after sand blasting.

6. The method for nickel plating aviation titanium alloy parts according to claim 5, characterized in that: The weak acid activation in S701 uses a nitric acid solution with a volume concentration of 5-10%, and the activation time is 30-60s.

7. The method for nickel plating aviation titanium alloy parts according to claim 1, characterized in that: The S8 comprises the following steps: S801: Observe whether there is a gray-black matrix on the surface of the titanium alloy parts. If so, it means that the nickel layer has fallen off and the product is unqualified; otherwise, the titanium alloy parts with no nickel layer falling off are subjected to S802; S802: Measure the coating thickness of titanium alloy parts whose nickel layer has not fallen off, and classify the titanium alloy parts with qualified coating thickness into Group A, the titanium alloy parts with coating thickness exceeding the tolerance within 0.005mm into Group B, and the titanium alloy parts with coating thickness exceeding the tolerance by more than 0.005mm and requiring multiple polishing and repairing into Group C; S803: Polish the titanium alloy parts of group A to qualified standard using diamond sandpaper with grit of 800-1200 mesh; S804: Use an abrasive cloth roll with a rotation speed of 200-300rpm and a removal rate of ≤0.001mm / time to evenly remove and polish the titanium alloy parts in group B to a qualified size, and then proceed to S803; S805: For the titanium alloy parts of group C, use an abrasive cloth roll with a rotation speed of 200-300rpm and a removal rate of ≤0.001mm / time to evenly polish them for one circle, then cool them to 20±5℃. After cooling time ≥15min, repeat polishing again until the qualified size is reached, and then proceed to S803.

8. The method for nickel plating aviation titanium alloy parts according to claim 7, characterized in that: S801 The surface of the titanium alloy parts described in the experiment is observed with the assistance of an endoscope to determine the nickel layer shedding condition. Parts with a gray-black matrix area exceeding 5% are deemed scrapped.

9. The method for nickel plating aviation titanium alloy parts according to claim 1, characterized in that: The S9 comprises the following steps: S901: Dimension inspection: Use a three-coordinate measuring machine to verify the dimensional tolerance, with an allowable deviation of ±0.005mm; S902: Coating inspection: The nickel layer thickness is measured by X-ray fluorescence spectrometry, and the uniformity deviation is ≤±0.003mm.

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