Characterization of the recasting-affected zone in the nickel-based superalloy upon single-pulse laser treatment

The wide application of various laser techniques is motivating research of microstructural evolution in laser manufactured materials and quantification of its mechanical performance. In the present work, the existence and performance of a recasting-affected zone (RAZ) between the melting-solidified material and the base material after single-pulse laser treatment were experimentally and computationally investigated. The RAZ strengthened by thermal plastification, twin formation and δ phase dissolution possesses a higher yield strength and can provide an effective strengthening mechanism for laser manufacturing components of the nickel-based superalloy, which was further verified in the analysis of the double aging-treated specimen. However, the micro-cracks nucleated during the laser manufacturing are distributed near the RAZ surface and can reduce the fracture strain and fatigue life of the component significantly. The high thermal gradients from the solidification were verified to be responsible for the plastic strengthening and micro-crack formation in RAZ.