Additive repair method for damage of KK3 aluminum bronze aircraft cam

Abstract

The invention relates to the technical field of additive repair, in particular to a KK3 aluminum bronze aircraft cam damage additive repair method which comprises the steps that S1, alloy is prepared; s2, determining a material-grade test item and a performance index according to the stress working condition of the product, and carrying out a material-grade test; and S3, aircraft cam damage laser additive repair is carried out. According to the method, the two kinds of repairing powder GH4169 and KK3 are preferably selected according to the characteristics of a base material, and it is effectively guaranteed that the mechanical property after repairing meets the use requirement; and the inter-pass temperature is strictly controlled, the next pass is subjected to laser additive repair after the temperature of the previous repair layer is reduced to 40 DEG C or below, and deformation caused by heat accumulation is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of additive repair, and in particular to a method for additive repairing a damaged KK3 aluminum bronze aircraft cam. Background Art

[0002] KK3 aluminum bronze, according to GB / T5231, its grade is QAL10-4-4-1. This alloy is heat-treatable and strengthened aluminum bronze with aluminum, iron, nickel and manganese as the main alloying elements. In the final heat-treated state, its tensile strength is (900-1010) MPa and its hardness is (250-300) HB. KK3 aluminum bronze has low specific gravity, high tensile strength, wear resistance and corrosion resistance. It is mainly used in landing gear, door parts, drag parachutes and other parts of certain models of aircraft. At present, the aircraft cam made of KK3 aluminum bronze is used in conjunction with the 300M steel piston rod. At the same time, the surface of the 300M steel piston rod is prepared with a tungsten carbide wear-resistant coating. When the aircraft tilts during flight, the aircraft cam made of KK3 aluminum bronze and the tungsten carbide wear-resistant coating on the piston rod surface produce friction. The hardness of the KK3 aluminum bronze material is not as high as that of the tungsten carbide coating. Compared with the tungsten carbide coating, aluminum bronze is not wear-resistant, which causes the KK3 aluminum bronze aircraft cam to wear during use, and then causes the inner wall size of the aircraft cam to be out of tolerance, making it difficult to assemble and seal at this position, and the overall performance is reduced. At present, damaged aviation parts are generally restored to their functions through additive repair. Laser additive repair is gradually used in the repair of damaged aviation parts due to its high energy density, small heat input, fast crystallization speed, fine grains of the repair layer, and good mechanical properties of the repair layer.

[0003] Since the damaged area of ​​the inner wall of the aircraft cam is large and the repair layer is required to have good bonding performance with the substrate, the conventional laser additive repair process is prone to deformation and metallurgical defects. Based on this, the present invention provides a KK3 aluminum bronze aircraft cam damage additive repair method. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a method for additively repairing damaged KK3 aluminum bronze aircraft cams.

[0005] A KK3 aluminum bronze aircraft cam damage additive repair method, the specific steps are as follows:

[0006] S1. Preparation of alloy: According to the chemical composition of the aircraft cam material, the heat treatment system and the stress conditions of the product, the repair powder is determined to be two powders of the same material GH4169 and KK3. The specific composition is as follows:

[0007] (1) GH4169 alloy powder is prepared by gas atomization method or plasma rotating electrode method, and the specific chemical composition requirements Wt.% are as follows: C: ≤0.08; Cr: 17-21; Ni: 50-55; Mo: 2.8-3.3; Al: 0.2-0.8; Ti: 0.65-1.15; Nb: 4.75-5.5; O: ≤0.02; Fe: Bal;

[0008] (2) The chemical composition requirements of KK3 alloy powder prepared by gas atomization method are as follows: Al: 8.5-11; Fe: 3-5; Ni: 3-5; Mn: 0.5-2; O: ≤0.03; Cu: Bal;

[0009] S2. Determine material-level test items, performance indicators and carry out material-level tests according to product stress conditions:

[0010] (1) The repair powder has friction and wear along the cylinder wall;

[0011] (2) According to the product's stress requirements, the product's tensile strength and shear strength shall not be less than 90% of the base material, and the friction coefficient of the repair layer shall be less than 0.28;

[0012] (3) Material level test:

[0013] The tensile, shear and friction wear samples of KK3 matrix, KK3 matrix laser additive GH4169 powder and KK3 matrix laser additive KK3 powder were prepared, and the performance of the samples was tested. The GH4169 powder and KK3 powder were repaired by laser additive. The tensile strength and shear force were not less than 90% of the matrix parent material, and the friction coefficient was less than 0.28.

[0014] S3. Carry out laser additive repair of aircraft cam damage:

[0015] (1) Structural analysis of the aircraft cam. The aircraft cam needs to be clamped on a positioner for rotary laser additive manufacturing. At the same time, the holes on the repair surface need to be sealed with fireproof mud before repair to avoid damage to the circular holes during laser additive manufacturing repair.

[0016] (2) After the aircraft cam is clamped, laser cladding is carried out. Laser additive repair is carried out by rotating the positioner and fixing the laser cladding head. In order to reduce the defects of the cladding layer, a small spot repair is used. After the temperature of the previous repair layer drops below 40°C, the laser additive repair is carried out for the next layer. The interlayer temperature is monitored by an infrared thermometer;

[0017] (3) After the cam is repaired by laser additive manufacturing, mechanical processing is carried out according to the aircraft cam drawing;

[0018] (4) The machined aircraft cam can be put into use after fluorescent flaw detection and if there is no crack.

[0019] The sphericity of the GH4169 alloy powder in step S1 is ≥0.9.

[0020] The particle size range of the GH4169 alloy powder in step S1 is 53 μm-150 μm, wherein the particle size <53 μm accounts for ≤5%, and the particle size >150 μm accounts for ≤5%.

[0021] The sphericity of the KK3 alloy powder in step S1 is ≥0.9.

[0022] The particle size range of the KK3 alloy powder in step S1 is: 53μm-150μm, of which <53μm accounts for ≤5%, and >150μm accounts for ≤5%.

[0023] The spot diameter of step S3 is controlled within 1-1.2 mm.

[0024] The beneficial effects of the present invention are as follows: according to the characteristics of the matrix material, two kinds of repair powders, GH4169 and KK3, are selected to effectively ensure that the mechanical properties after repair meet the use requirements; the temperature between passes is strictly controlled, and the laser additive repair of the next pass is performed after the temperature of the previous repair layer drops to below 40°C, so as to avoid deformation due to heat accumulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0026] Figure 1 It is a schematic diagram of the workpiece structure of the present invention;

[0027] Figure 2 It is a schematic diagram of the process structure of the present invention. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below.

[0029] like Figure 1 to Figure 2 As shown, a KK3 aluminum bronze aircraft cam damage additive repair method, Figure 1 The reference numeral a in the figure indicates three non-repair holes on the annular surface, and the reference numeral b in the figure indicates the worn annular surface area to be repaired. The specific steps are as follows:

[0030] S1. Preparation of alloy: The powder composition for laser additive repair is determined according to the chemical composition of the aircraft cam material, the heat treatment system and the stress conditions of the product. Considering the wear resistance of the repair coating and the requirements for material matching, the repair powders are GH4169 and KK3. The two repair powders are selected according to the characteristics of the matrix material, which effectively ensures that the mechanical properties after repair meet the use requirements. The specific composition is as follows:

[0031] (1) GH4169 alloy powder is prepared by gas atomization method or plasma rotating electrode method, and the specific chemical composition requirements Wt.% are as follows: C: ≤0.08; Cr: 17-21; Ni: 50-55; Mo: 2.8-3.3; Al: 0.2-0.8; Ti: 0.65-1.15; Nb: 4.75-5.5; O: ≤0.02; Fe: Bal;

[0032] (2) The chemical composition requirements of KK3 alloy powder prepared by gas atomization method are as follows: Al: 8.5-11; Fe: 3-5; Ni: 3-5; Mn: 0.5-2; O: ≤0.03; Cu: Bal;

[0033] S2. Determine material-level test items, performance indicators and carry out material-level tests according to product stress conditions:

[0034] (1) The repair powder has friction and wear along the cylinder wall, so the repair layer is subjected to friction, shear force perpendicular to the cylinder wall, and bonding force between the repair layer and the substrate. Therefore, the material-level test detects room temperature tensile strength, friction and wear, and shear force;

[0035] (2) According to the product's stress requirements, the product's tensile strength and shear strength shall not be less than 90% of the base material, and the friction coefficient of the repair layer shall be less than 0.28;

[0036] (3) Material level test:

[0037] The tensile, shear and friction wear samples were prepared for KK3 matrix, KK3 matrix laser additive GH4169 powder, KK3 matrix laser additive KK3 powder, and the performance of the samples was tested. The results are shown in the following table. After performance comparison, the tensile strength and shear force of laser additive repair using GH4169 powder and KK3 powder of the same material are not less than 90% of the matrix parent material, and the friction coefficient is less than 0.28;

[0038]

[0039] S3. Carry out laser additive repair of aircraft cam damage:

[0040] (1) Structural analysis of the aircraft cam shows that the aircraft cam needs to be clamped on a positioner for rotary laser additive manufacturing. At the same time, the holes on the repair surface need to be sealed with fireproof mud before repair to avoid damage to the circular holes during laser additive manufacturing.

[0041] (2) After the aircraft cam is clamped, laser cladding is carried out. The laser additive repair is carried out by rotating the positioner and fixing the laser cladding head. At the same time, a small spot repair is used to reduce the defects of the cladding layer. In order to prevent the cam deformation caused by continuous laser additive heat accumulation, the inter-pass temperature is strictly controlled. The next laser additive repair is carried out after the temperature of the previous repair layer drops below 40°C. The inter-layer temperature is monitored by an infrared thermometer.

[0042] The specific process parameters of a single pass are shown in the following table;

[0043]

[0044] (3) After the cam is repaired by laser additive manufacturing, mechanical processing is carried out according to the aircraft cam drawing;

[0045] (4) The machined aircraft cam can be put into use after fluorescent flaw detection and cracks are found. The product repair cycle is greatly shortened, avoiding the long spare parts procurement cycle caused by replacement, and effectively ensuring production.

[0046] The sphericity of the GH4169 alloy powder in step S1 is ≥0.9.

[0047] Fireproof mud is used to seal the areas that do not need repair to avoid damage to the areas that do not need repair due to the passage of laser, which is beneficial to improving the quality of repair.

[0048] The particle size range of the GH4169 alloy powder in step S1 is 53 μm-150 μm, wherein the particle size <53 μm accounts for ≤5%, and the particle size >150 μm accounts for ≤5%.

[0049] The sphericity of the KK3 alloy powder in step S1 is ≥0.9.

[0050] The particle size range of the KK3 alloy powder in step S1 is: 53μm-150μm, of which <53μm accounts for ≤5%, and >150μm accounts for ≤5%. The use of GH4169 and KK3 powder to repair the aircraft cam effectively ensures that the mechanical properties of the repaired aircraft cam meet the use requirements.

[0051] The spot diameter of step S3 is controlled at 1-1.2 mm. A small diameter spot is used for repair, which has high laser energy density and small deformation, thereby improving the repair quality. At the same time, the temperature between passes is strictly controlled. The temperature of the previous repair layer is reduced to below 40°C before the laser additive repair of the next layer is performed to avoid deformation due to heat accumulation.

[0052] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A KK3 aluminum bronze aircraft cam damage additive repair method, characterized in that: The specific steps are as follows: S1. Preparation of alloy: According to the chemical composition of the aircraft cam material, the heat treatment system and the stress conditions of the product, the repair powder is determined to be two powders of the same material GH4169 and KK3. The specific composition is as follows: (1) GH4169 alloy powder is prepared by gas atomization method or plasma rotating electrode method, and the specific chemical composition requirements Wt.% are as follows: C: ≤0.08; Cr: 17-21; Ni: 50-55; Mo: 2.8-3.3; Al: 0.2-0.8; Ti: 0.65-1.15; Nb: 4.75-5.5; O: ≤0.02; Fe: Bal; (2) The chemical composition requirements of KK3 alloy powder prepared by gas atomization method are Wt.%: Al: 8.5-11; Fe: 3-5; Ni: 3-5; Mn: 0.5-2; O: ≤0.03; Cu: Bal; S2. Determine material-level test items, performance indicators and carry out material-level tests according to product stress conditions: (1) The repair powder has friction and wear along the cylinder wall; (2) According to the product's stress requirements, the product's tensile strength and shear strength shall not be less than 90% of the base material, and the friction coefficient of the repair layer shall be less than 0.28; (3) Material level test: The tensile, shear and friction wear samples of KK3 matrix, KK3 matrix laser additive GH4169 powder and KK3 matrix laser additive KK3 powder were prepared, and the performance of the samples was tested. The GH4169 powder and KK3 powder were repaired by laser additive. The tensile strength and shear force were not less than 90% of the matrix parent material, and the friction coefficient was less than 0.

28. S3. Carry out laser additive repair of aircraft cam damage: (1) Structural analysis of the aircraft cam. The aircraft cam needs to be clamped on a positioner for rotary laser additive manufacturing. At the same time, the holes on the repair surface need to be sealed with fireproof mud before repair to avoid damage to the circular holes during laser additive manufacturing repair. (2) After the aircraft cam is clamped, laser cladding is carried out. Laser additive repair is carried out by rotating the positioner and fixing the laser cladding head. In order to reduce the defects of the cladding layer, a small spot repair is used. After the temperature of the previous repair layer drops below 40°C, the laser additive repair is carried out for the next layer. The interlayer temperature is monitored by an infrared thermometer; (3) After the cam is repaired by laser additive manufacturing, mechanical processing is carried out according to the aircraft cam drawing; (4) The machined aircraft cam can be put into use after fluorescent flaw detection and if there is no crack.

2. The additive repair method for KK3 aluminum bronze aircraft cam damage according to claim 1, characterized in that: The sphericity of the GH4169 alloy powder in step S1 is ≥0.

9.

3. The additive repair method for KK3 aluminum bronze aircraft cam damage according to claim 1, characterized in that: The particle size range of the GH4169 alloy powder in step S1 is 53 μm-150 μm, wherein the particle size <53 μm accounts for ≤5%, and the particle size >150 μm accounts for ≤5%.

4. The additive repair method for KK3 aluminum bronze aircraft cam damage according to claim 1, characterized in that: The sphericity of the KK3 alloy powder in step S1 is ≥0.

9.

5. The additive repair method for KK3 aluminum bronze aircraft cam damage according to claim 1, characterized in that: The particle size range of the KK3 alloy powder in step S1 is: 53μm-150μm, of which <53μm accounts for ≤5%, and >150μm accounts for ≤5%.

6. The additive repair method for KK3 aluminum bronze aircraft cam damage according to claim 1, characterized in that: The spot diameter of step S3 is controlled within 1-1.2 mm.

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