Surface formation mechanism in waterjet guided laser cutting of a Ni-based superalloy

Waterjet guided laser (WJGL) cutting is a relatively new technology for high-precision machining of difficult-to-cut materials. However, its material removal mechanism presents some unique features because of the interaction between laser, waterjet and workpiece. This paper investigates the surface formation mechanism in WJGL cutting of Ni-based superalloy and its influence on the fatigue performance. Two different microstructures have been found on the surface layer, i.e. recast crystals and redeposited amorphous oxide, resulting from solidification of melt and plasma respectively under the laser-waterjet interaction. Mechanical twinning structures were also revealed in the substrate due to the waterjet confined plasma shockwave impact.