A method for laser brazing additive repair of HPb59-1 high-zinc lead brass and application thereof

Abstract

The application discloses a kind of HPb59-1 high-zinc lead brass laser brazing additive repair method and application, belong to high-zinc lead brass brazing additive technical field.The application applies laser brazing additive repair technology to aircraft HPb59-1 high-zinc lead brass damage repair, solves the evaporation of Pb, Zn element in HPb59-1 alloy due to conventional fusion welding repair, which not only harms human health, but also reduces the mechanical properties of welded joint, improves the damage repair quality of aircraft HPb59-1 high-zinc lead brass parts.

Description

Technical Field

[0001] The present invention relates to the technical field of high-zinc-lead brass brazing additive technology, and more particularly to a HPb59-1 high-zinc-lead brass laser brazing additive repair method and application. Background Art

[0002] HPb59-1 alloy is a medium-lead (α+β) two-phase brass, a high-zinc brass. This alloy exhibits high strength, excellent machinability, and formability, making it suitable for hot working. However, it exhibits a strong tendency to stress corrosion damage. Cold-work-hardened materials and parts should undergo stress-relief annealing at low temperatures. Its tensile strength ranges from 392 MPa to 480 MPa. This non-heat-treatable copper alloy is primarily used in the manufacture of aircraft parts such as gears and bushings. However, long-term service can lead to wear of HPb59-1 alloy components, impacting component performance and posing a threat to flight safety.

[0003] Repairs by replacing them with new ones are costly and often hinder the repair process due to difficulties in supplying spare parts, thus affecting production.

[0004] At present, the thread damage of HPb59-1 alloy electrical column is usually repaired by fusion welding. However, the melting point of HPb59-1 alloy is between 886℃ and 901℃. The mass fractions of the chemical elements in the alloy are: Pb 0.8%-1.9%, Zn 38%-42%, and Cubal. The melting point of Pb is 327.5℃. Lead is also a toxic heavy metal that is harmful to the human body, especially at high temperatures, it will release toxic lead vapor. The melting point of Zn is 419.53℃. The fusion welding process causes the Pb and Zn elements in the alloy to evaporate, which not only endangers human health but also reduces the mechanical properties of the welded joint.

[0005] Based on this, the present invention provides an additive repair process for the problem of repairing damage to HPb59-1 composite parts of aircraft, which effectively improves the quality of additive repair of HPb59-1 composite parts of aircraft. Summary of the Invention

[0006] In view of this, the present invention provides a laser brazing additive repair method and application of HPb59-1 high-zinc-lead brass, which effectively improves the additive repair quality of aircraft HPb59-1 composite parts.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A laser brazing additive repair method for HPb59-1 high-zinc-lead brass comprises the following steps:

[0009] (1) Using DSC differential scanning calorimetry to measure the melting point of the prepared solder powder;

[0010] (2) Clean the area to be repaired. Laser clean the end surface of the area to be repaired to remove the oxide layer, ensure that the metal luster is exposed, the surface is clean, and then clean it with acetone;

[0011] (3) The defects are confirmed to be eliminated through non-destructive testing, and the parts other than the repaired area that may be irradiated by the laser are covered with a protective layer;

[0012] (4) Evenly mix the flux 101 and the solder powder, and place the mixed powder into a powder feeding bucket in a powder feeder;

[0013] (5) Carry out optimization of laser brazing process parameters to ensure that the temperature of the laser temperature field during laser brazing is between 809°C and 829°C. The temperature of the laser temperature field is detected online using an online infrared thermometer.

[0014] (6) During the process of laser brazing additive repair and shape control, the interlayer temperature is strictly controlled. When the interlayer temperature drops below 40°C, the next layer is repaired by laser additive. The interlayer temperature is detected by an infrared thermometer.

[0015] (7) After repairing one layer during the laser brazing additive repair process, laser cleaning is used to clean the surface of the additive repair layer to remove the oxide layer, ensuring that the metallic luster is exposed and the surface is clean and cleaned with acetone, and then the next layer is repaired and steps (6) to (7) are repeated;

[0016] (8) After the repair is completed, it is machined into standard size;

[0017] (9) After machining is completed, it can be delivered for use if no cracks are found using fluorescent testing.

[0018] Preferably, the solder powder comprises: 53.5-54.5 wt% Ag; 45.5-46.5 wt% Cu, and its melting range is 760°C-810°C.

[0019] Preferably, the sphericity of the solder powder is ≥0.9.

[0020] Preferably, the solder powder has a particle size of 45 μm-105 μm, and particles <45 μm account for ≤5%, and particles >105 μm account for ≤5%.

[0021] Preferably, the solder powder is prepared by a plasma rotating electrode method.

[0022] Preferably, the volume ratio of the flux 101 to the solder powder is 1:2.

[0023] Preferably, the flux 101 is a mixture of potassium fluoroborate and boric acid in a mass ratio of (68-71): (32-29).

[0024] Preferably, the laser brazing process parameters are:

[0025] Powder feeding gas: 99.999% high purity argon;

[0026] Laser brazing alloy powder uses silver-based brazing powder;

[0027] Laser power: 900-1300W;

[0028] Scanning speed: 8-10mm / s;

[0029] Spot diameter: 2mm;

[0030] Powder feeder speed: 0.8-1r / min;

[0031] Powder feeding gas flow rate: 4-6L / min;

[0032] Shielding gas flow rate: 18-20L / min;

[0033] Overlap rate: 40%-50%.

[0034] Another object of the present invention is to provide an application of the above-mentioned HPb59-1 high zinc-lead brass laser brazing additive repair method in the repair of damage to aircraft HPb59-1 high zinc-lead brass.

[0035] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention applies laser brazing additive repair technology to the repair of damage to aircraft HPb59-1 high-zinc-lead brass, solving the problem of evaporation of Pb and Zn elements in the HPb59-1 alloy caused by conventional fusion welding repair, which not only harms human health but also reduces the mechanical properties of the welded joints. It improves the quality of damage repair of aircraft HPb59-1 high-zinc-lead brass parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0038] Figure 1 It is a process flow chart of the present invention.

[0039] Figure 2 This is the metallographic diagram of the optimal silver-based solder brazing material.

[0040] Figure 3This is the brazing metallographic diagram of the silver-based solder ratio No. 1.

[0041] Figure 4 This is the brazing metallographic diagram of the silver-based solder ratio No. 2.

[0042] Figure 5 This is the brazing metallographic diagram of base solder ratio No. 3.

[0043] Figure 6 This is the brazing metallographic diagram of base solder ratio No. 4. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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 efforts are within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment provides a laser brazing additive repair method for HPb59-1 high-zinc-lead brass, wherein the brazing alloy powder has the following specific composition: Ag 53.5%, Cu 46.5%.

[0047] Solder alloy powder sphericity: ≥0.9;

[0048] The particle size range of solder alloy powder is: 45μm-105μm, of which <45μm accounts for ≤5%, and >105μm accounts for ≤5%.

[0049] The solder alloy powder was prepared by plasma rotating electrode method.

[0050] The flux 101 is a mixture of potassium fluoroborate and boric acid, with a mass ratio of 70:30.

[0051] The particle size of the flux 101 powder is ≤105μm.

[0052] Laser brazing, its specific process parameters are:

[0053] Powder feeding gas: 99.999% high purity argon;

[0054] Laser power: 1000W;

[0055] Scanning speed: 10mm / s;

[0056] Spot diameter: 2mm

[0057] Powder feeder speed 0.9r / min;

[0058] Powder feeding gas flow rate: 5L / min;

[0059] Shielding gas flow rate: 20L / min;

[0060] Overlap rate: 50%.

[0061] The specific steps include:

[0062] (1) The melting point of the prepared solder powder was measured by DSC differential scanning calorimetry and was 779°C;

[0063] (2) Cleaning of the area to be repaired. Use laser cleaning to remove the oxide layer on the end face of the area to be repaired, ensuring that the metallic luster is exposed and the surface is clean, and then clean it with acetone.

[0064] (3) The elimination of defects needs to be confirmed by non-destructive testing. Aluminum foil should be used to protect other parts of the parts that may be irradiated by the laser except the repair area to prevent the laser irradiation from damaging the substrate of other parts during the repair process.

[0065] (4) Evenly mix the flux 101 and the solder powder in a volume ratio of 1 part of flux 101 powder to 2 parts of solder powder, and place the mixed powder in a powder feeding bucket of a powder feeder.

[0066] (5) Carry out optimization of laser brazing process parameters to ensure that the temperature of the laser temperature field during laser brazing is between 809°C and 829°C. The temperature of the laser temperature field is detected online using an online infrared thermometer.

[0067] (6) The interlayer temperature should be strictly controlled during the process of laser brazing additive repair and shape control. When the interlayer temperature drops below 40°C, the next layer can be repaired by laser additive. The interlayer temperature is detected by an infrared thermometer.

[0068] (7) During the laser brazing additive repair process, after repairing one layer, the surface of the additive repair layer is cleaned by blasting to remove the oxide layer, ensuring that the metallic luster is exposed and the surface is clean and cleaned with acetone. Then, the next layer is repaired and steps (6) to (7) are repeated.

[0069] (8) After the repair is completed, it is machined into standard size;

[0070] (9) After machining is completed, it can be delivered for use if no cracks are found using fluorescent testing.

[0071] Mechanical properties verification

[0072] At the same time, according to the working conditions of high-zinc-lead brass aircraft parts made of HPb59-1 alloy in the aviation maintenance field, it can be seen that the material-level test shows that the bonding performance between the repair layer and the substrate is not less than 80% of the tensile strength of the substrate to meet the use requirements. The material-level test shows that the tensile strength after laser brazing is 325MPa, which meets the use requirements.

[0073] Some parameters of the present invention were modified as comparative examples, see Table 1 for details:

[0074] Table 1

[0075]

[0076] The present invention adopts brazing to repair the damage of the HPb59-1 alloy parts, avoiding the evaporation of Pb and Zn elements in the HPb59-1 alloy caused by fusion welding repair, which not only harms human health but also reduces the mechanical properties of the welded joint.

[0077] In the prior art, fusion welding repair is performed at a temperature higher than the melting point of the substrate, which causes the evaporation of Pb and Zn elements, reduces the strengthening effect, and has a tensile strength lower than 280 MPa. The present invention uses laser brazing to ensure welding repair at a temperature lower than the melting point of the substrate, with a tensile strength higher than 320 MPa.

[0078] The present invention adopts laser as heat source for brazing, thereby ensuring small brazing deformation and improving repair quality.

[0079] The specific parameters of laser brazing are obtained through process optimization; compared with oxyacetylene flame heat source and arc heat source, laser brazing has less deformation.

[0080] The present invention mixes the flux 101 and the solder powder evenly in a volume ratio of 1 part flux 101 powder to 2 parts solder powder, which can effectively remove the oxide film generated during the brazing process due to poor protection of coaxially transported high-purity argon and improve the brazing quality.

[0081] Laser brazing without adding flux 101 powder will only produce a partial oxide film under the protection of argon gas, and the brazing surface will be partially gray; laser brazing with adding flux 101 powder will show a silvery white surface.

[0082] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0083] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A laser brazing additive repair method for HPb59-1 high zinc-lead brass, characterized in that: The following steps are involved: (1) The melting point of the prepared solder powder was measured using a DSC differential scanning calorimeter; (2) Clean the area to be repaired. Laser clean the end surface of the area to be repaired to remove the oxide layer, ensure that the metal luster is exposed, the surface is clean, and then clean it with acetone; (3) The defects are confirmed to be eliminated through non-destructive testing, and a protective layer is applied to other parts of the part that may be irradiated by the laser except the repair area; (4) Evenly mix the flux 101 and the solder powder, and place the mixed powder into the powder feeding bucket of the powder feeder; (5) Develop laser brazing process parameters to ensure that the temperature of the laser temperature field during laser brazing is between 809°C and 829°C. The temperature of the laser temperature field is detected online using an online infrared thermometer. (6) During the process of laser brazing additive repair and shape control, the interlayer temperature is strictly controlled. The next layer is repaired by laser additive repair after the interlayer temperature drops below 40°C. The interlayer temperature is detected by an infrared thermometer. (7) After repairing one layer during the laser brazing additive repair process, laser cleaning is used to clean the surface of the additive repair layer to remove the oxide layer, ensure that the metal luster is exposed, the surface is clean and cleaned with acetone, and then the next layer is additively repaired and steps (6) to (7) are repeated; (8) After the repair is completed, it is machined into standard size; (9) After machining is completed, it can be delivered for use if no cracks are found using fluorescent testing; The solder powder composition includes: Ag 53.5-54.5wt%; Cu 45.5-46.5wt%, and its melting range is 760℃-810℃; The laser brazing process parameters are: Powder feeding gas: 99.999% high purity argon; Laser brazing alloy powder uses silver-based brazing powder; Laser power: 900-1300W; Scanning speed: 8-10mm / s; Spot diameter: 2 mm; Powder feeder speed: 0.8-1r / min; Powder feeding gas flow rate: 4-6L / min; Shielding gas flow rate: 18-20L / min; Overlap rate: 40%-50%.

2. The laser brazing additive repair method for HPb59-1 high zinc-lead brass according to claim 1, characterized in that: The sphericity of the solder powder is ≥0.

9.

3. The laser brazing additive repair method for HPb59-1 high zinc-lead brass according to claim 2, characterized in that: The solder powder has a particle size of 45 μm to 105 μm, and the particle size of the solder powder less than 45 μm is allowed to account for ≤5%, and the particle size greater than 105 μm is allowed to account for ≤5%.

4. The laser brazing additive repair method for HPb59-1 high zinc-lead brass according to claim 1, characterized in that: The solder powder is prepared by a plasma rotating electrode method.

5. The laser brazing additive repair method for HPb59-1 high zinc-lead brass according to claim 1, characterized in that: The volume ratio of the flux 101 to the solder powder is 1:

2.

6. The laser brazing additive repair method for HPb59-1 high zinc-lead brass according to claim 5, characterized in that: The flux 101 is made of a mixture of potassium fluoroborate and boric acid in a mass ratio of (68-71):(32-29), wherein the flux 101 powder particle size is ≤105 μm.

7. Application of the laser brazing additive repair method for HPb59-1 high zinc-lead brass according to any one of claims 1 to 6 in repairing damage to HPb59-1 high zinc-lead brass in aircraft.

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