Laser Shock Technology of Workpiece Surface Using Surface Micro-texture to Remove Residual Stress Hole

Abstract

The invention relates to a workpiece surface laser shocking process utilizing surface micro textures for removing residual stress holes. Micro texture laser parameters are optimized, the purpose of releasing residual stress is achieved through array micropores formed by the laser micro textures, and meanwhile, the micropores formed by the micro textures play a role in blocking in the rarefaction wave transmitting process, surface converged waves cannot arrive at a light spot center, the residual stress holes cannot be formed, and a PDVF piezoelectric sensor is used for carrying out monitoring on the workpiece surface to ensure that rarefaction waves cannot be converged towards the light spot center. In addition, the laser parameter of laser shocking peening is converted into a laser parameter of deionized water serving as a restraint layer, and therefore the process can be applied to the industry on a large scale. The process is used for carrying out laser shocking peening treatment on the workpiece surface, the residual stress holes can be directly removed without changing the light spot shape and without a high overlap rate, and the machining cost is reduced while the machining efficiency is improved.

Description

technical field [0001] The invention relates to a laser shock process on the surface of a workpiece for removing residual stress holes by using surface micro-texture, and belongs to the technical field of laser processing. Background technique [0002] Laser Shocking Peening (LSP) technology, also known as laser peening technology. Laser shock peening is the use of high power density (GW / cm 2 level), short pulse (10-30ns level) laser irradiates the energy absorbing layer coated on the metal surface through the confinement layer, the coating absorbs the laser energy and vaporizes rapidly and forms a large number of dense high-temperature (710K ), high pressure (>1GPa) plasma. The confinement layer can effectively enhance the pressure of the laser shock wave and prolong its duration, hinder the plasma explosion, enhance the laser energy coupling, and significantly improve the strengthening effect of the laser shock. [0003] The surface micro-texture process has been pro...

AI Technical Summary

Problems solved by technology

The appearance of the phenomenon of "residual stress hole" leads to the loss of compressive stress in the center of the laser shock strengthening spot, and even the formation of tensile stress, which makes the spot form a large stress gradient. In actual production and application, it is very easy to cause workpieces after laser shock strengthening. Cracks occur, seriously reducing life

[0005] Changing the Gauss circular spot to a uniform square spot by the "optical binary diffraction" method can effectively suppress the formation of "residual stress holes" and form a relatively uniform residual compressive stress layer, but the maximum residual compressive stress value of the surface formed by the square spot and The depth of the plastic-affected layer will be reduced to a certain extent, and the processing cost is high

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