Investigation on the Laves phase formation during laser cladding of IN718 alloy by CA-FE

Abstract

A deleterious Laves phase forms in the solidified structure of Inconel 718 (IN718) alloy during laser cladding, and the dynamic formation of Laves phase is difficult to be observed by experiments directly. In this paper, a novel multi-scale numerical model was established. As a consequence, the influence of the laser cladding process parameters on solidification parameters was analyzed, especially on shape control factor (K) and cooling rate (R) firstly. Afterward, a series of dynamic solidification processes were simulated, including nucleation, dendrites growth, solute distribution and Laves phase formation. Furthermore, the refined Laves phase was obtained by optimization of laser cladding processing parameters and the cooling environments. Finally, the proposed model was further testified by experiments. From the results of simulations and experiments, that high cooling rate inhibited composition undercooling in molten pool and decreased the secondary dendrite arm spacing. At the same time, the niobium (Nb) segregation was improved and Laves phase was refined in cladding layer. The presented investigation provided a comprehensive understanding of the Laves phase formation in IN718 alloy during laser cladding, and had certain reference significance on minimizing the Laves phase concentration in actual processing.