Process parameter optimization of K477 and GH4169 for defect control in laser-directed energy deposition using Taguchi design of experiments

Turbine blisk used for aerospace engines withstands harsh working environments and requires multiple materials suited for different function requirements. Laser-directed energy deposition (L-DED) is ideal for manufacturing of multi-material turbine blisk. This study investigates the L-DED manufacturability of two dissimilar nickel-based superalloys K477 and GH4169 used for multi-material turbine blisk. K477 is prone to produce defects such as cracks and pores because of its high Ti and Al compositions, and the bimetallic transition zone of the multi-material turbine blisk is also easy to generate cracks. Therefore, the effects of process parameters (laser power P_L, scanning speed v, and powder feed rate m_p) on the defects during L-DED of the single materials (i.e., 100% K477 or 100% GH4169) and the transition zone material (50 wt% K477 + 50 wt% GH4169) are assessed. The internal defect optimization of K477 fabricated by L-DED is achieved by using the Taguchi orthogonal experiment design. The optimized results show that unfused defects and cracks of K477 disappear, and a high cross-sectional density up to 99.98% is obtained, which indicates the possibility of controlling internal defect through the proposed process parameter optimization method. This work provides a reasonable parameter optimization method for L-DED process in the engineering applications of multi-material parts.