Method for prolonging service life of turbine blade based on laser double-faced impact technique

Abstract

The invention relates to a method for prolonging the service life of a turbine blade based on a laser double-faced impact technique. The method comprises the following steps: firstly carrying out equal-energy laser beam splitting by virtue of a Nd:YAG pulsed laser; then simultaneously impacting the front and rear surfaces by virtue of gradually-changed light spot overlapping rate by taking running water as a restraint layer so as to strength the root of the blade, fixing the turbine blade by virtue of a fixture, and simultaneously impacting the front and rear surfaces of the bottommost layer of the root of the blade by virtue of high-energy large-light-spot pulse laser and 90% of the overlapping rate; when impact strengthening at each height is finished, descending a lifting platform by a height of the light spot diameter, and impacting by virtue of the overlapping rate which is 10% smaller than the former overlapping rate; and finishing the laser impact strengthening of the root of the blade until the overlapping rate is 0. According to the method, the disadvantage of insufficient mechanical shot blasting influence depth is made up, and by impacting the root of the blade by virtue of the gradually-changed overlapping rate, the distribution change of a residual stress field becomes flat; by virtue of laser double-faced impact manner, the deformation and damage of the blade caused by laser single-faced impact are avoided, and meanwhile, the front and rear surfaces of the blade are equally stressed.

Description

technical field [0001] The invention relates to a method for improving the service life of a turbine blade based on laser double-sided shock technology, and belongs to the technical fields of surface engineering technology and laser processing. Background technique [0002] Both laser shock strengthening and shot peening technology are methods to generate compressive stress on the surface of materials and refine grains, thereby improving the fatigue strength of metal components. However, the disadvantage of shot peening is that the residual stress affects the depth less. Laser shock strengthening uses short pulse (ns), high power density (>1GW / cm2) laser irradiation to induce the formation of plasma high pressure (>1GPa) shock waves, which act on the surface of the workpiece and propagate to the inside, and the material undergoes high strain rate Dynamic response, causing microstructural changes, produces residual compressive stresses in deeper thicknesses. Therefore...

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Problems solved by technology

For example, patent CN103014278A discloses a method for improving blade fatigue strength by comprehensive means, but in this method, laser shock strengthening is not aimed at the easily damaged area, that is, the blade heel, and the strengthening effect is not obvious. Large deformation of parts; patent CN103146893A discloses a method of laser shock treatment of curved surfaces, the processing of curved surfaces is adjusted according to the magnitude of the current, and the overall parts are processed, the workload is cumbersome, and there is only one processing head during work, which can only Suitable for single side processing

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