A process for repairing ultra-high-strength steel by laser cladding

Abstract

The application relates to the field of aviation maintenance and remanufacturing technology, in particular to a super-high-strength-steel laser cladding repair process method, which comprises the following steps: detecting damage position characteristics, adopting homogenous material to preposition in the damage area of the super-high-strength steel, adopting coaxial or paraxial powder feeding mode high-power laser cladding, laser remelting the cladding layer every 2 cladding layers, alternately performing 2-layer laser cladding and 1-layer laser remelting, and effectively solving the problem that the transverse tensile strength and toughness are low due to epitaxial growth of columnar crystals in the cladding process, thereby affecting the crack resistance.

Description

Technical Field

[0001] This invention relates to the field of aviation maintenance and remanufacturing technology, specifically to a laser cladding repair process for ultra-high strength steel. Background Technology

[0002] Ultra-high strength steel possesses high fracture toughness and can withstand high stress, making it widely used in materials such as connecting rods, drive shafts, and landing gear in aerospace vehicles, such as AerMet100 ultra-high strength steel forgings. These components face extensive wear in their contact areas during operation, leading to performance loss and frequent component replacement. Therefore, repairing these components can extend their service life and reduce replacement costs.

[0003] Traditional arc welding and plasma additive repair methods cause significant damage to the strength of ultra-high-strength steel due to their large heat input. Laser cladding, on the other hand, has a low heat input and offers advantages and feasibility for additive repair of ultra-high-strength steel. For example, application number 202210852347.3, entitled "A Laser Repair Method for Landing Gear Cracks," describes a method that uses laser shock annealing to pre-stress the repair area, followed by coaxial laser annular powder feeding to scan and repair the crack defect layer by layer from bottom to top. Another example is application number 201611031700.2, entitled "Preparation Method and Application of Laser Cladding Layer on the Surface of Ultra-High-Strength Low-Carbon Alloy Steel," which discloses a laser cladding method for 30CrMnSiNi2A ultra-high-strength steel used in aircraft landing gear. The proposed laser cladding process involves the direct deposition of a homogeneous alloy layer.

[0004] However, the laser cladding direct deposition layer in the above methods has the characteristics of epitaxial columnar crystal growth, and its transverse (perpendicular to the deposition direction) service crack resistance is poor, which leads to the limitations and technical bottlenecks of laser cladding additive repair of ultra-high strength steel components.

[0005] Based on the above reasons, this invention designs a laser cladding repair process for ultra-high strength steel, filling the domestic gap in the repair of damage to this type of material components. This process, which repairs wear or other defects through laser cladding, solves the problem of reduced strength and toughness of the repair layer in ultra-high strength steel. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a laser cladding repair process for ultra-high strength steel, filling the domestic gap in the repair of damage to this type of material components. This process, which repairs wear or other defects through laser cladding, solves the problem of reduced strength and toughness of the repair layer in ultra-high strength steel.

[0007] To achieve the above objectives, the present invention provides a laser cladding repair process for ultra-high strength steel, comprising the following steps: S1, detect the location characteristics of the damage; based on the damage characteristics, perform fatigue layer machining and cleaning on the damaged area; S2 uses homogeneous materials and high-power laser cladding with coaxial or off-axis powder feeding in the damaged area. Two layers are clad, and then the cladding layer is laser-remelted. The process of two layers cladding and one layer remelting is repeated. The laser cladding power is about 2 to 3 times that of laser remelting. S3, in every two laser cladding layers, the scanning speed of the first laser cladding layer is 17-24 mm / s, and the scanning speed of the second laser cladding layer is 5-12 mm / s; the scanning speed of the laser remelting layer is 2-6 mm / s; for the repair of planar defects, the weld direction of the laser cladding layer and the laser remelting layer should be 30-90° apart. S4, for the overall wear repair of shaft parts, uses spiral trajectory laser cladding repair, and then the cladding layer is remelted by spiral trajectory laser in the opposite direction; as the number of welding layers increases, this is repeated until the repair size is reached.

[0008] Compared with the prior art, the present invention has the following beneficial effects: High-power laser cladding is performed on the damaged area of ​​ultra-high strength steel using homogeneous materials, with pre-positioned, coaxial or off-axis powder feeding. After every two layers are clad, the clad layer is laser remelted. This alternating process of two laser cladding layers and one laser remelting layer effectively solves the problem of low transverse tensile strength and toughness caused by the epitaxial growth of columnar crystals during the cladding process, which affects crack resistance. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the repair process of the present invention.

[0010] Explanation of reference numerals in the attached figures: 1 represents ultra-high strength steel, 2 represents the laser beam, 3 represents the repair area, 4 represents the laser cladding layer, and 5 represents the laser remelting layer. Implementation

[0011] The present invention will now be further described with reference to the accompanying drawings.

[0012] See Figure 1 This invention provides a laser cladding repair process for ultra-high strength steel, comprising the following steps: S1, detect the location characteristics of the damage; based on the damage characteristics, perform fatigue layer machining and cleaning on the damaged area; S2 uses homogeneous materials and high-power laser cladding with coaxial or off-axis powder feeding in the damaged area. Two layers are clad, and then the cladding layer is laser-remelted. The process of two layers cladding and one layer remelting is repeated. The laser cladding power is about 2 to 3 times that of laser remelting. S3, in every two laser cladding layers, the scanning speed of the first laser cladding layer is 17-24 mm / s, and the scanning speed of the second laser cladding layer is 5-12 mm / s; the scanning speed of the laser remelting layer is 2-6 mm / s; for the repair of planar defects, the weld direction of the laser cladding layer and the laser remelting layer should be 30-90° apart. S4, for the overall wear repair of shaft parts, uses spiral trajectory laser cladding repair, and then the cladding layer is remelted by spiral trajectory laser in the opposite direction; as the number of welding layers increases, this is repeated until the repair size is reached. Example

[0013] The surface of ultra-high strength steel AerMet100 steel is worn, and the fatigue layer depth of the machined surface is 1.0 mm.

[0014] First, laser cladding is applied to the first layer: the laser power is set to 2.5kW, the linear speed is 5mm / s, and AerMet100 alloy powder is fed coaxially to apply the first layer of laser cladding to the wear area of ​​the shaft.

[0015] Laser remelting of the first layer: The laser power is set to 1.0kW, the linear speed is 3mm / s, and the laser scanning direction is 90° different from the direction of the first laser cladding layer. Laser remelting is performed on the first laser cladding layer in the wear area to form the remelted first layer.

[0016] Continuing, the second layer of laser cladding is performed: the linear speed is 18 mm / s, and the laser scanning direction is the same as the first layer. The first layer is laser clad in the wear area of ​​the shaft. Then the speed is adjusted to 6 mm / s, and the second layer is laser clad in the wear area of ​​the shaft. Thus, the second layer of laser cladding is completed.

[0017] Then, the second layer is laser-remelted: the laser power is set to 1.0kW, the linear velocity to 6mm / s, and the laser scanning direction is 90° different from the direction of the second laser cladding layer. Laser remelting is performed on the second laser cladding layer in the wear area of ​​the shaft to form a remelted second layer. The above steps are repeated until the fifth laser cladding layer is reached, and the additive thickness in the wear area of ​​AerMet100 steel is 2.5mm. Example

[0018] The cylindrical surface of an ultra-high strength AerMet100 steel shaft was worn. The fatigue layer on the worn surface was machined to a depth of 1.0 mm. The worn shaft was then clamped on a rotary chuck. The first layer was laser-clad: the laser power was set to 3.0 kW, the rotary chuck speed was adjusted to a shaft linear velocity of 12 mm / s, and AerMet100 alloy powder was fed coaxially. The laser scanning direction was to the left along the axis, and the first layer was laser-clad in the worn area of ​​the shaft. The first layer was then laser-remelted: the laser power was set to 1.0 kW, the rotary chuck speed was adjusted to a shaft linear velocity of 3 mm / s, and the laser scanning direction was to the right along the axis. The first layer was laser-remelted on the worn area of ​​the shaft, forming a remelted first layer. Continuing with the second laser cladding layer: The rotating head is adjusted to a surface linear velocity of 24 mm / s on the shaft, with the laser scanning direction to the left along the axis. The first layer is laser-clad in the wear area of ​​the shaft. The rotating head is then adjusted to a surface linear velocity of 12 mm / s, with the laser scanning direction still to the left along the axis. The second layer is laser-clad in the wear area of ​​the shaft. This completes the second laser cladding layer. Next, the second layer is laser-remelted: The laser power is set to 1.0 kW, the rotating head speed is adjusted to a surface linear velocity of 3 mm / s on the shaft, and the laser scanning direction is to the right along the axis. The second layer is laser-remelted on the wear area of ​​the shaft, forming a remelted second layer. The above steps are repeated until the fourth laser cladding layer is reached, resulting in an additive thickness of 2.0 mm in the wear area of ​​the AerMet100 steel shaft.

[0019] Working principle: For ultra-high strength steel 1, the damaged and cracked areas are first inspected and treated by removing the damaged surface and cleaning. Then, in the damaged repair area 3 of ultra-high strength steel 1, pre-placed, coaxial or off-axis powder feeding is used to clad the area with a high-power laser beam 2. Two laser cladding layers 4 are clad together, and then the cladding layers are remelted with a laser to form a laser remelted layer 5. After alternating between two laser cladding layers and one laser remelted layer, a certain additive thickness is formed to complete the repair.

[0020] The above are merely preferred embodiments of the present invention, intended only to aid in understanding the method and core ideas of this application. The scope of protection of the present invention is not limited to the above embodiments; all technical solutions falling within the scope of the present invention's concept are within its protection. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0021] This invention comprehensively solves the problem in the prior art where the low transverse tensile strength and toughness caused by the epitaxial growth of columnar crystals during the cladding process affects crack resistance. By using homogeneous materials to perform high-power laser cladding in the damaged area of ​​ultra-high strength steel using pre-positioned, coaxial or off-axis powder feeding, and performing laser remelting on every two cladding layers, alternating between two laser cladding layers and one laser remelting layer, the repair process improves the repair effect of ultra-high strength steel components, extends their service life, and reduces replacement costs.

Claims

1. A laser cladding repair process for ultra-high strength steel, characterized in that, Includes the following steps: S1, detects the location characteristics of the damage; Based on the damage characteristics, the fatigue layer of the damaged area is machined and cleaned. S2 uses homogeneous materials and employs high-power laser cladding with coaxial or off-axis powder feeding in the damaged area. First, the first layer is laser-clad, then the first layer is laser-remelted. Next, the first and second layers of the second layer are laser-clad, and then the second layer is laser-remelted. This process of alternating between two-layer cladding and one-layer remelting is repeated until the preset number of cladding layers is reached. The laser cladding power is 2 to 3 times that of the laser remelting power. S3, in every two laser cladding layers, the scanning speed of the first laser cladding layer is 17-24 mm / s, and the scanning speed of the second laser cladding layer is 5-12 mm / s; the scanning speed of the laser remelting layer is 2-6 mm / s; for the repair of planar defects, the weld direction of the laser cladding layer and the laser remelting layer needs to be 30-90° apart; S4, for the overall wear repair of shaft parts, uses spiral trajectory laser cladding repair, and then the cladding layer is remelted by spiral trajectory laser in the opposite direction; as the number of welding layers increases, this is repeated until the repair size is reached.

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