Method for repairing 1Cr17Ni5 martensitic stainless steel thin-wall pipe fitting through laser cladding additive

Abstract

The invention relates to the field of laser cladding additive repairing of thin-walled pipe parts, in particular to a method for repairing a 1Cr17Ni5 martensitic stainless steel thin-walled pipe fitting through laser cladding additive, which comprises the following specific steps: S1, determining laser cladding parameters; s2, a pipe fitting to be repaired is clamped; s3, polishing is conducted; s4, cleaning is conducted; s5, additive repairing is carried out; and S6, carrying out post-treatment. According to the method, the 1Cr17Ni2 powder which is similar to a base material in component, excellent in performance and commercialized and commercial is adopted for laser cladding additive repairing, the repairing performance of the 1Cr17Ni5 martensitic stainless steel thin-wall pipe fitting repaired through the method is excellent, the hardness of the damaged pipe fitting is improved while shape repairing is achieved, meanwhile, the high-speed laser cladding technology is adopted, and the service life of the damaged pipe fitting is prolonged. And heat input is low, repairing deformation is small, the additive repairing requirement of thin-walled pipe parts is met, and the application prospect is wide.

Description

Technical Field

[0001] The invention relates to the field of laser cladding additive repair of thin-walled pipe parts, and specifically to a method for laser cladding additive repair of 1Cr17Ni5 martensitic stainless steel thin-walled pipe fittings. Background Art

[0002] 1Cr17Ni5 martensitic stainless steel has high strength, hardness and good processing performance and is widely used in the manufacture of aircraft parts and accessories. During the use of aviation parts and accessories, the outer surface of some 1Cr17Ni5 stainless steel thin-walled pipes and fittings undergo micro-wear, and large-area and certain-depth damage occurs on the outer surface of the pipes and fittings, resulting in the inability to use the tubular parts normally. In the past, during maintenance, the damaged parts and accessories were usually replaced with new parts for subsequent use. However, due to the high cost and long manufacturing cycle of aviation parts and accessories, the long-term replacement of damaged parts and accessories leads to high maintenance costs, and also causes a lot of resource waste. Therefore, an additive repair method with good repair effect is needed to reduce maintenance and use costs. Laser cladding additive repair technology with laser as heat source has the advantages of low heat input and small repair deformation, and is suitable for the repair of thin-walled parts. However, there are big differences between the repair process of rotating parts such as thin-walled pipes and thin-walled plate parts: the repair of rotating parts usually adopts the method of rotating the parts and slowly moving the heat source, while the repair of plate parts usually adopts the method of keeping the parts stationary and moving the heat source quickly; at the same time, 1Cr17Ni5 is a martensitic stainless steel that differs from other stainless steels in composition, structure, and cladding forming. Summary of the invention

[0003] In order to solve the above problems, the present invention proposes a method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive manufacturing.

[0004] The method of laser cladding additive repair of 1Cr17Ni5 martensitic stainless steel thin-walled pipe fittings has the following specific steps:

[0005] S1. Determine laser cladding parameters: According to the damaged area range of the outer wall of the 1Cr17Ni5 martensitic stainless steel thin-walled pipe, measure the maximum damage depth to calculate the laser cladding parameters, determine the scanning speed of the cladding head according to the laser cladding parameters, and determine the time required for the laser work during the cladding process according to the width of the damaged area;

[0006] S2. Clamping the pipe to be repaired: clamping, fixing and rotating the pipe to be repaired by a motor and a three-jaw chuck, and controlling the rotation speed of the pipe to be repaired;

[0007] S3. Grinding: Grind the outer wall of the damaged pipe to make it smooth;

[0008] S4. Cleaning: Use acetone to clean the oil stains on the surface of the damaged area;

[0009] S5. Additive repair: Additively repair the damaged pipe outer wall according to the determined cladding parameters, cladding head scanning speed and laser working time;

[0010] S6. Post-processing: Machining is used to restore the thin-walled pipe to its original size to complete the additive repair.

[0011] In the step S1, the wall thickness of the damaged pipe is in the range of 0.8-1.5 mm, and the diameter of the pipe is in the range of 35-60 mm.

[0012] The step S1 uses a measuring tool to measure the damaged area, specifically, to measure the width perpendicular to the end face of the pipe and the maximum damage depth of the damaged area.

[0013] The laser cladding parameters of step S1 include laser power, rotation speed, and powder feeding speed.

[0014] The laser power is 700-1200W, the powder feeding speed is 1-3r / min, and the rotation speed is 40-80r / min.

[0015] A set of parameters is selected according to the laser power, rotation speed and powder feeding speed and substituted into the relationship between the cladding height and the cladding parameters. When the calculated cladding height is greater than 1.2*maximum damage depth and the power / rotation speed is as small as possible, this parameter is selected as the subsequent cladding repair parameter.

[0016] The relationship between the cladding parameters and the cladding height and cladding width is:

[0017] Single-pass cladding layer height (μm) = 76.292 + 72.124 * powder feeding speed + 0.06222 * power - 2.3684 * speed;

[0018] Single-pass cladding layer width (μm) = 557.392-58*powder feeding speed+1.02796*power-7.9126*rotation speed.

[0019] Substitute the cladding parameters into the relationship between the cladding parameters and the cladding width to obtain the cladding width of a single pass. Then, according to the cladding head scanning speed (mm / s) = single pass cladding width * rotation speed / 120, the cladding head scanning speed is obtained; according to the laser working time (s) = damage width / cladding head scanning speed, the laser working time is determined.

[0020] The step S3 is to polish the damaged area with sandpaper to make the groove at the bottom of the damaged area smooth and reveal the metallic luster.

[0021] After determining the cladding parameters, the scanning speed of the cladding head, and the laser working time, the step S5 is set accordingly in the device, and then the motor is rotated at a speed, the cladding head moves at a calculated moving speed directly above the pipe and parallel to the axis of the pipe, and the laser scans the entire damaged area according to the set working time to complete the cladding repair.

[0022] The material powder used in the additive repair of step S5 is 1Cr17Ni2 powder with a composition similar to that of the base material, a particle size between 20-53um, a powder sphericity greater than 90%, a powder feeding gas flow rate of 4-6L / min, and a central protective gas flow rate of 6-8L / min.

[0023] The beneficial effects of the present invention are as follows: the present invention adopts 1Cr17Ni2 powder which has a composition similar to that of the substrate, has excellent performance and is commercially available for laser cladding additive repair. The 1Cr17Ni5 martensitic stainless steel thin-walled pipe fittings repaired by this method have excellent repair performance. While achieving shape repair, the hardness of the damaged pipe fittings is improved. At the same time, the high-speed laser cladding technology adopted by the present invention has low heat input and small repair deformation, which meets the additive repair needs of thin-walled pipe parts and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] Figure 1 It is a schematic diagram of the definition of the width and height of a single-pass cladding layer of the present invention;

[0026] Figure 2 The macroscopic morphology of the surface after laser cladding repair of the damaged area according to the present invention;

[0027] Figure 3 This is the cross-sectional morphology of the laser cladding repair area 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 Figures 1 to 3 As shown in the figure, the method of laser cladding additive repair of 1Cr17Ni5 martensitic stainless steel thin-walled pipe fittings has the following specific steps:

[0030] S1. Determine laser cladding parameters: According to the damaged area range of the outer wall of the 1Cr17Ni5 martensitic stainless steel thin-walled pipe, measure the maximum damage depth to calculate the laser cladding parameters, determine the scanning speed of the cladding head according to the laser cladding parameters, and determine the time required for the laser work during the cladding process according to the width of the damaged area;

[0031] S2. Clamping the pipe to be repaired: clamping, fixing and rotating the pipe to be repaired by a motor and a three-jaw chuck, and controlling the rotation speed of the pipe to be repaired;

[0032] S3. Grinding: Grind the outer wall of the damaged pipe to make it smooth;

[0033] S4. Cleaning: Use acetone to clean the oil stains on the surface of the damaged area;

[0034] S5. Additive repair: Additively repair the damaged pipe outer wall according to the determined cladding parameters, cladding head scanning speed and laser working time;

[0035] S6. Post-processing: Machining is used to restore the thin-walled pipe to its original size to complete the additive repair.

[0036] The present invention realizes the additive repair of damaged 1Cr17Ni5 martensitic thin-walled stainless steel pipes, with a short repair cycle, which can effectively reduce the maintenance and use costs of aviation accessories. At the same time, the method has low heat input, small deformation of the pipe after repair, high hardness of the repair layer, and effectively improves the wear resistance of the pipe.

[0037] In the step S1, the wall thickness of the damaged pipe is in the range of 0.8-1.5 mm, and the diameter of the pipe is in the range of 35-60 mm.

[0038] The step S1 uses a measuring tool to measure the damaged area, specifically, to measure the width perpendicular to the end face of the pipe and the maximum damage depth of the damaged area.

[0039] The laser cladding parameters of step S1 include laser power, rotation speed, and powder feeding speed.

[0040] The laser power is 700-1200W, the powder feeding speed is 1-3r / min, and the rotation speed is 40-80r / min.

[0041] A set of parameters is selected according to the laser power, rotation speed and powder feeding speed and substituted into the relationship between the cladding height and the cladding parameters. When the calculated cladding height is greater than 1.2*maximum damage depth and the power / rotation speed is as small as possible, this parameter is selected as the subsequent cladding repair parameter.

[0042] The present invention adopts 1Cr17Ni2 powder which has a composition similar to that of the substrate, has excellent performance and is commercially available for laser cladding additive repair. The 1Cr17Ni5 martensitic stainless steel thin-walled pipe fittings repaired by this method have excellent repair performance. While achieving shape repair, the hardness of the damaged pipe fittings is improved. At the same time, the high-speed laser cladding technology adopted by the present invention has low heat input and small repair deformation, which meets the additive repair needs of thin-walled pipe parts and has broad application prospects.

[0043] The relationship between the cladding parameters and the cladding height and cladding width is:

[0044] Single-pass cladding layer height (μm) = 76.292 + 72.124 * powder feeding speed + 0.06222 * power - 2.3684 * speed;

[0045] Single-pass cladding layer width (μm) = 557.392-58*powder feeding speed+1.02796*power-7.9126*rotation speed.

[0046] Substitute the cladding parameters into the relationship between the cladding parameters and the cladding width to obtain the cladding width of a single pass. Then, according to the cladding head scanning speed (mm / s) = single pass cladding width * rotation speed / 120, the cladding head scanning speed is obtained; according to the laser working time (s) = damage width / cladding head scanning speed, the laser working time is determined.

[0047] The step S3 is to polish the damaged area with sandpaper to make the groove at the bottom of the damaged area smooth and reveal the metallic luster.

[0048] After determining the cladding parameters, the scanning speed of the cladding head, and the laser working time, the step S5 is set accordingly in the device, and then the motor is rotated at a speed, the cladding head moves at a calculated moving speed directly above the pipe and parallel to the axis of the pipe, and the laser scans the entire damaged area according to the set working time to complete the cladding repair.

[0049] The high-speed laser cladding method is used to perform additive repair on the outer surface of 1C17Ni5 stainless steel thin-walled pipe fittings. High-speed laser cladding uses a rotary tooling to rotate the pipe fittings to be processed, and then uses a laser heat source to heat and melt the matrix and powder to form a molten pool. After the molten pool solidifies, the damage repair is completed. This technology has the advantages of low heat input and small repair deformation for the repair of rotating thin-walled parts.

[0050] The material powder used in the additive repair of step S5 is 1Cr17Ni2 powder with a composition similar to that of the base material, with a particle size between 20-53um, a powder sphericity greater than 90%, a powder feeding gas flow rate of 4-6L / min, and a central protective gas flow rate of 6-8L / min. The wall thickness of the damaged pipe is in the range of 0.8-1.5mm, and the diameter of the pipe is in the range of 35-60mm.

[0051] Among them, the carbon mass percentage in 1Cr17Ni5 martensitic stainless steel is 0.11-0.17%, the chromium content percentage is 6-18%, the nickel content percentage is 4-6%, and the balance is iron.

[0052] The diameter of the laser spot for cladding repair is in the range of 1-1.2mm, and the diameter of the powder spot is in the range of 1-1.5mm.

[0053] Embodiment 1

[0054] The outer diameter of a tubular accessory of an aircraft fuel system is 50mm, the length is 70mm, and the wall thickness is 1mm. Due to long-term use, the outer wall of this accessory is scratched over a large area. After measurement, the maximum damage depth of the scratched area is 196μm, and the width of the damaged area is 47mm. The damaged area was then polished with sandpaper and cleaned with acetone. After calculation, when the power is 1200W, the pipe speed is 50r / min, and the powder feeding speed is 3r / min, the single-pass cladding height is 249μm, 249>196*1.2, and the heat input is relatively small under this parameter, so this parameter is selected as the cladding parameter. The definition of the width and height of the single-pass cladding layer is as follows Figure 1 As shown in the figure, the reference symbol a is the width of a single cladding layer, and the reference symbol b is the height of a single cladding layer. The cladding width under this parameter is calculated to be 1221μm. According to the formula, the scanning speed of the cladding head is 0.5mm / s, and the laser working time is 94s. According to the above parameters, the corresponding settings are made in the cladding device, and then the cladding repair is started. The surface morphology of the accessory after repair is as follows Figure 2 The cross-sectional morphology of the cladding layer is shown in Figure 3 As shown. Finally, according to the original size of the accessory, the outer diameter is 50mm, and the accessory is machined to restore it to its original size to complete the additive repair. The hardness of the cladding layer is measured to be 553HV, and the hardness of the substrate is 387HV. This method greatly improves the hardness of the accessory while completing the repair of the accessory.

[0055] Embodiment 2

[0056] The outer surface of a tubular accessory of an aircraft fuel system is damaged. The outer diameter of the tubular accessory is 50mm, the length is 70mm, and the wall thickness is 1mm. After measurement, the maximum damage depth of the damaged area is 94μm and the width of the damaged area is 32mm. The damaged area was then polished with sandpaper and cleaned with acetone. It was calculated that when the power is 1000W, the pipe speed is 70r / min, and the powder feeding speed is 2r / min, the single-pass cladding height is 117μm, 117>94*1.2, and the heat input is relatively small under this parameter, so this parameter is selected as the cladding parameter. It is calculated that the cladding width under this parameter is 915μm. According to the formula, the scanning speed of the cladding head is 0.53mm / s, and the laser working time is 61s. According to the above parameters, the corresponding settings are made in the cladding device, and then the cladding repair is started. After the cladding is completed, the accessories are machined according to the original size of the accessories, the outer diameter is 50mm, and it is restored to its original size to complete the additive repair.

[0057] 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 method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive, characterized in that: The specific steps are as follows: S1. Determine laser cladding parameters: According to the damaged area range of the outer wall of the 1Cr17Ni5 martensitic stainless steel thin-walled pipe, measure the maximum damage depth to calculate the laser cladding parameters, determine the scanning speed of the cladding head according to the laser cladding parameters, and determine the time required for the laser work during the cladding process according to the width of the damaged area; S2. Clamping the pipe to be repaired: clamping, fixing and rotating the pipe to be repaired by a motor and a three-jaw chuck, and controlling the rotation speed of the pipe to be repaired; S3. Grinding: Grind the outer wall of the damaged pipe to make it smooth; S4. Cleaning: Use acetone to clean the oil stains on the surface of the damaged area; S5. Additive repair: Additively repair the damaged pipe outer wall according to the determined cladding parameters, cladding head scanning speed and laser working time; S6. Post-processing: Machining is used to restore the thin-walled pipe to its original size to complete the additive repair.

2. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 1, characterized in that: In the step S1, a measuring tool is used to measure the damaged area, specifically, the width perpendicular to the end face of the pipe and the maximum damage depth of the damaged area are measured. The wall thickness of the damaged pipe is in the range of 0.8-1.5 mm, and the diameter of the pipe is in the range of 35-60 mm.

3. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 1, characterized in that: The laser cladding parameters of step S1 include laser power, rotation speed, and powder feeding speed.

4. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 3 is characterized in that: The laser power is 700-1200W, the powder feeding speed is 1-3r / min, and the rotation speed is 40-80r / min.

5. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 4, characterized in that: A set of parameters is selected according to the laser power, rotation speed and powder feeding speed and substituted into the relationship between the cladding height and the cladding parameters. When the calculated cladding height is greater than 1.2*maximum damage depth and the power / rotation speed is as small as possible, this parameter is selected as the subsequent cladding repair parameter.

6. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 5, characterized in that: The relationship between the cladding parameters and the cladding height and cladding width is: Single-pass cladding layer height μm = 76.292 + 72.124 * powder feeding speed + 0.06222 * power - 2.3684 * speed; The width of a single cladding layer μm = 557.392-58*powder feeding speed+1.02796*power-7.9126*rotation speed.

7. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 6, characterized in that: Substitute the cladding parameters into the relationship between the cladding parameters and the cladding width to obtain the cladding width of a single pass. Then, according to the cladding head scanning speed (mm / s) = single pass cladding width * rotation speed / 120, the cladding head scanning speed is obtained; according to the laser working time (s) = damage width / cladding head scanning speed, the laser working time is determined.

8. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 1, characterized in that: The step S3 is to polish the damaged area with sandpaper to make the groove at the bottom of the damaged area smooth and reveal the metallic luster.

9. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 1, characterized in that: After determining the cladding parameters, the scanning speed of the cladding head, and the laser working time, the step S5 is set accordingly in the device, and then the motor is rotated at a speed, the cladding head moves at a calculated moving speed directly above the pipe and parallel to the axis of the pipe, and the laser scans the entire damaged area according to the set working time to complete the cladding repair.

10. The method for repairing 1Cr17Ni5 martensitic stainless steel thin-walled pipes by laser cladding additive according to claim 1, characterized in that: The material powder used in the additive repair of step S5 is 1Cr17Ni2 powder with a composition similar to that of the base material, a particle size between 20-53um, a powder sphericity greater than 90%, a powder feeding gas flow rate of 4-6L / min, and a central protective gas flow rate of 6-8L / min.

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