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Conventional laser processing of metals will form serious heat affected zone, micro cracks, burrs and recast layer, resulting in rough machined surface and serious slag accumulation. As a new type of laser-waterjet composite processing method, waterjet guided laser can reduce or even eliminate heat affected zone, thermal crack, recast layer and burr. It has the advantages of high surface quality, strong depth ability and large depth-to-diameter ratio structure. Nickel-based single crystal superalloy is widely used in advanced aero-engine turbine blades for their excellent overall performance. With waterjet guided laser processing technology, this paper study the influence of process parameters on the grooving morphology and quality of DD6 nickel-based single crystal superalloy. A multi-factor study on the influence of laser power, laser repetition frequency, waterjet velocity and feeding speed on grooving was carried out with a self-developed waterjet guided laser processing device. The depth-to-width ratio and sidewall taper of the machined groove were measured and analyzed by using a three-dimensional confocal laser scanning microscope. The experimental results show that the grooves taper can be decreased with reducing the laser repetition frequency and increasing the laser power. The grooves large depth processing is improved by reducing the feeding speed, increasing the laser power, reducing the laser repetition frequency and increasing the waterjet velocity. The cutting experiment of 1 mm DD6 nickel-based single crystal superalloy was achieved with better processing process parameters, and it was found that the upper and lower surface roughness of the cutting surface was inconsistent, providing a theoretical basis for the study of high quality processing of nickel-based single-crystal superalloy by waterjet guided laser.

Water jet-guided laser technology is an efficient processing technology that offers the advantages of a small heataffected zone and strong depth capability when processing a variety of difficult-to-process materials. However, the surface of the laminar water column can form irregular disturbances due to nozzle damage and other factors, ultimately leading to an uneven distribution of laser light intensity, causing a loss of laser power. In this paper, the relationship between the quality, morphology and coupling alignment errors of the water column on the optical transmission efficiency of water-guided lasers is investigated in depth with ray tracing method. Besides, the water column surface variable-angle prismatic disturbance model is established, considering the characteristics of the real water column to research the impact of the real situation relationship. The results show that the loss of laser energy is more severe as the complexity of the surface morphology of the water column increases. In addition, laser coupling alignment errors are studied. The results show that a circular distribution is formed in the water column when the alignment deviation occurs. Finally, the reasons affecting the laminar flow conditions are analyzed to provide theoretical support for efficient laminar coupled light transmission.