Electrochemical anisotropy of Hastelloy X fabricated by selective laser melting in a NaNO3 solution

Abstract

The microstructure and electrochemical behavior of Hastelloy X fabricated by selective laser melting were investigated. The microstructure of selective laser melted Hastelloy X mainly comprises columnar crystals grown along the deposition direction, consisting of fine columnar dendrites. The results of the electrochemical tests conducted using a 10 wt% NaNO3 solution show that the passive film that formed on the horizontal section (HS) and vertical section (VS) presented p-type semiconductor properties, but the stability and protectiveness of the passive film that formed on the VS was better than those of that on the HS. The surface morphology after dissolution indicates that the dissolution rate of the interdendritic region was faster than that of the dendritic trunk, which resulted in a faster dissolution rate for the center of the molten pool than that of the edge of the molten pool, and the dissolution rate of the HS was faster than that of the VS.