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Method for repairing fatigue cracks by cold spraying

A fatigue cracking and cold spraying technology, applied in pressure inorganic powder coating and other directions, can solve the problems of stress concentration in deteriorated and strengthened parts, reduction of static strength of components, instability and other problems, and achieve the effect of eliminating stress concentration and prolonging extended life.

Inactive Publication Date: 2019-05-10
XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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  • Application Information

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Problems solved by technology

At the same time, the weakened section of the drill hole will reduce the static strength of the component and cause other problems; the crack welding method will deteriorate the fracture toughness of the weld metal and the steel in the heat-affected zone during the welding process, making this area have a large welding residue Stress, and welding defects such as pores, inclusions, and cracks in the weld may cause the initiation and propagation of new fatigue cracks; the steel plate reinforcement method should be arranged symmetrically on both sides, otherwise, the out-of-plane bending moment generated by the eccentric load will deteriorate the reinforced part The stress concentration of the infiltration filling method is uncertain due to the instability of the actual filling process.

Method used

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  • Method for repairing fatigue cracks by cold spraying
  • Method for repairing fatigue cracks by cold spraying
  • Method for repairing fatigue cracks by cold spraying

Examples

Experimental program
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Effect test

Embodiment 1

[0042] The fatigue test is carried out by making a standard single-side notched three-point bending specimen, such as Figure 2 ~ Figure 4 . First, the surface of the sample is polished with 100 mesh, 500 mesh, 1000 mesh and 1500 mesh sandpaper in sequence, then alcohol cleaning and sandblasting, and the aluminum powder with a particle size of 15±5μm is passed through the high pressure gas by the powder feeder 1 through the gas heater After 4, it is accelerated and sent to the Laval nozzle 2, and the aluminum powder is deposited on the surface of the substrate 3 to complete the repair and strengthening. Specific parameters used in cold spraying: main force air pressure 1.0MPa, powder feeding rate 15g / min, distance between spraying and substrate 12mm, spraying moving speed 15mm / s, gas heating temperature 300°C. The cold sprayed aluminum coating is 3mm thick and sanded to 2mm with 3000 grit sandpaper. Then, put the standard unilateral notched three-point bending specimen repai...

Embodiment 2

[0044] The fatigue test is carried out by making a standard single-side notched three-point bending specimen, such as Figure 2 ~ Figure 4 . First, the surface of the sample is polished with 100 mesh, 500 mesh, 1000 mesh and 1500 mesh sandpaper in sequence, then cleaned with alcohol, and sandblasted with corundum sand, and the A5052 aluminum alloy powder with a particle size of 15±5 μm is fed by the powder feeder 1 The high-pressure gas is accelerated into the Laval nozzle 2 after passing through the gas heater 4, and the aluminum powder is deposited on the surface of the substrate 3 to complete the repair and strengthening. Specific parameters used in cold spraying: main force air pressure 1.0MPa, powder feeding rate 16g / min, distance between spraying and substrate 15mm, spraying moving speed 10mm / s, gas heating temperature 350°C. The thickness of the cold-sprayed aluminum coating is 3mm, and it is sanded to 2mm with 3000-grit sandpaper. Then, put the standard unilateral no...

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Abstract

The invention discloses a method for repairing fatigue cracks by cold spraying. The method is mainly used in the initial stage of fatigue crack growth. The method mainly comprises the following five steps including steel structure surface brightness and cleanliness treatment, treatment of sandblasting on the surface of the front edge of a steel structure crack tip for improving roughness, weak defect treatment after sandblasting on the surface of the front edge of the steel structure crack tip, steel structure fatigue crack tip front edge surface cold spray metal particle deposition coating repairing and cold spraying deposition coating leveling and polishing. A coating is deposited on the surface of the steel structure by a certain thickness to improve the fracture toughness of a member,the crack growth rate is decreased, and the fatigue life of the steel structural member is prolonged. In a specific embodiment, the repair effect is good, operation is convenient, the environmental pollution is small, the energy consumption is low, and the method has obvious more economic benefits.

Description

technical field [0001] The invention relates to a method for repairing fatigue cracks in metal structures, in particular to a method for repairing fatigue cracks in steel structures. Background technique [0002] For a long time, the calculation methods for structures or components in engineering are based on structural mechanics and material mechanics. They usually assume that the material is a uniform continuum without considering objectively existing cracks and defects. As long as the working stress does not exceed the allowable stress during calculation, the structure is considered safe, otherwise it is unsafe. The working stress is calculated according to the load conditions and the geometric dimensions of the components, and the allowable stress is selected according to the working conditions and material properties. [0003] For possible defects in the actual structure and other factors that cannot be considered, they are all considered in the safety factor. The saf...

Claims

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Application Information

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IPC IPC(8): C23C24/04B24B1/00B24C1/06
Inventor 杨俊芬杨景林谢坚曲凯
Owner XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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