Percussion Laser-Drilled Nickel-based Superalloys

Percussion laser drilling is a well-established technique for drilling cooling holes in gas turbine engine components and airfoils. Laser machining can, however, lead to a range of complex metallurgical effects particularly in the recast layer and heat-affected zone (HAZ) that may surround the drilled hole. It is important to understand these effects since the recast and HAZ could have a deleterious effect upon the mechanical properties of laser-drilled components. There have been several parametric studies in which a materials response to laser drilling has been analyzed with respect to the laser parameters. While such studies have incorporated optical and scanning electron microscopy to measure the extent of metallurgical effects in laser-drilled superalloys, there has been little high-resolution characterization done to reveal the microstructural changes that occur. Thus, the aim of the work was to utilize high-resolution electron microscopy techniques to reveal the details of the microstructural effects associated with percussion laser drilling of powder metallurgy (P/M) IN100.