Thermal composite underwater laser shock material surface modification method

Abstract

The invention provides a thermal composite underwater laser shock material surface modification method which comprises the following steps of building a processing platform of an underwater environment, adjusting pulse laser to be a circular pulse laser beam, and performing flat-top energy distribution; adjusting a focal point of the pulse laser beam and the surface of a to-be-processed material to be at positive defocusing amount, and ensuring that the energy density of the irradiated pulse laser beam received by the surface of the to-be-processed material is 1-5 GW / cm<2> and the thickness of a surface ablation layer is less than 200 micron, performing single-laser-beam laser shock treatment on the surface of the to-be-processed material by adopting the determined pulse laser condition, and determining the overlap rate during multi-point region laser shock treatment according to the microscopic mechanical property in a single-laser-beam irradiation region on the surface of the to-be-processed material; and carrying out actual material surface modification treatment by utilizing the determined laser beam impact condition. According to the method, the surface of the finally obtained material is smooth, residual stress is uniformly distributed, and the obtained material is in a mechanical property distribution state with hard outside and tough inside.

Description

technical field [0001] The invention relates to a material surface modification method for thermodynamic composite underwater laser shock, belonging to the technical field of material surface strengthening and modification. Background technique [0002] Laser shock material surface processing is a method based on the force effect of pulsed laser to achieve the purpose of material surface modification. In the conventional laser shock processing technology, the laser beam with ns level and faster pulse time induces high temperature and high pressure plasma to form a GPa level shock wave acting on the surface of the material, which is considered to be the material surface processing principle of the laser shock method. With the development of high-speed photography and other technologies, technicians proposed a new surface modification technology based on the combined use of plasma shock and cavitation effect based on the occurrence conditions of laser-induced underwater cavita...

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Problems solved by technology

[0003] In a liquid environment such as underwater, it is difficult to apply absorbing layer materials such as black tape; however, coating without an absorbing layer will cause severe ablation on the surface of the material, resulting in increased surface roughness and weakened tissue properties.

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