A dual physical effect pulsed laser shock method based on variable liquid confinement layer properties

Abstract

The invention relates to a double physical effect pulse laser shock method based on the physical properties of a variable liquid constrained layer, and belongs to the technical field of laser processing. The steps include (1) building a liquid confinement laser shock processing platform; (2) preparing a liquid confinement layer material with a specific optical refractive index; (3) detecting the liquid confinement layer material; (4) using the liquid confinement layer material to perform a single spot Uniform laser shock treatment of the irradiated area. The invention precisely controls the action intensity of the "plasma shock" effect and the "cavitation" effect in the pulse laser shock process under the liquid constraint condition, so that the material surface can obtain a uniform residual stress distribution state, and improve the fatigue resistance and stress corrosion resistance of the material and anti-fretting properties.

Description

technical field [0001] The invention relates to a double physical effect pulse laser shock method based on the physical properties of a variable liquid constrained layer, and belongs to the technical field of laser processing. Background technique [0002] Laser shock strengthening is a new type of surface strengthening technology. This technology uses short pulse laser as the medium and utilizes the mechanical effect of laser-induced shock waves to form large and deep residual compressive stress and structural changes on the metal surface, thereby significantly improving the metal surface. The service performance of materials such as anti-fatigue, anti-stress corrosion and anti-fretting wear. In laser shock peening production and processing, in order to reduce equipment costs, circular spot lasers are often used. [0003] During the laser shock process, the energy distribution of the laser beam generally adopts a flat-top or Gaussian form. In theory, when the laser energy ...

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Problems solved by technology

However, no matter which of the above-mentioned energy distribution modes of the laser beam is used in the actual operation process, the center of the spot is often not the position of the maximum residual compressive stress. On the contrary, the center of the spot will only form a lower residual compressive stress, that is, the formation of " "residual stress hole" phenomenon

The appearance of "residual stress hole" affects the strengthening effect of laser shock treatment, causes uneven distribution of residual stress field, affects the fatigue resistance and corrosion resistance of materials, and is not conducive to the full use of laser energy

[0004] Chinese patent document CN107858501B discloses a laser shock process on the surface of a workpiece to remove residual stress holes, optimizes the micro-texture laser parameters, and uses the array of small holes formed by the laser micro-texture to achieve the purpose of releasing residual stress. At the same time, the micro-texture The formed small hole plays a blocking role in the process of sparse wave propagation, so that the surface converged wave cannot reach the center of the spot, and the residual stress hole cannot be formed. The PDVF piezoelectric sensor is used to monitor the surface of the workpiece to ensure that the surface sparse wave cannot converge to the center of the spot.

This process is to suppress residual stress holes by adding additional processes to prepare surface micro-textures after the phenomenon of uneven distribution of residual stress induced by laser shock waves, so as to achieve uniform strengthening treatment of materials, adding additional processes Increased operating strength and reduced work efficiency

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