Femtosecond laser drilling in superalloy with water-based magnetic assistance

Experiment of femtosecond laser drilling in superalloy with water-based magnetic assistance was carried out. The effects of different environments (in air, magnetic assistance, water assistance and water-based magnetic assistance) on the hole morphology, hole diameter, taper angle and sidewall roughness after femtosecond laser drilling were compared and analyzed. The effects of magnetic flux density on the hole diameter, taper angle and sidewall quality with water-based magnetic assistance were discussed. The mechanism of femtosecond laser drilling in superalloy with water-based magnetic assistance was revealed. The results show that transverse magnetic assistance and water assistance could both improve the hole quality and drilling efficiency, and the effect of water assistance was greater than that of magnetic assistance. The drilling efficiency was the highest with water-based magnetic assistance, which was mainly manifested in the increase of the hole diameter, and the increase of the hole cross-section size; on the other hand, the hole quality was the best, which were mainly manifested in the increase of the perpendicularity of the hole cross-section, the decrease of the taper angle, the reduction of irregular micro scale defects such as grooves on the hole sidewall, and the decrease of the roughness of the hole sidewall. Compared with that in air, the hole taper angle was reduced by 24.63 %, and the hole sidewall roughness was reduced by 38.38 % with the water-based magnetic assistance. With the water-based magnetic assistance, the higher the magnetic flux density, the higher the hole quality. This research provided theoretical basis and technical support for femtosecond laser drilling.