Investigation on Microstructure, Hardness and Wear Resistance of Electron Beam Wire-Feeding Deposited Inconel 718 Alloy Coatings

Abstract

The Inconel 718 (IN718) alloy coatings were successfully fabricated using electron beam wire-feeding deposition technology. The macrostructure, microstructure and elemental analysis of the deposited coatings were characterized by OM, SEM and EDS. Moreover, the hardness and wear resistance were also investigated experimentally. The results showed that the cross section of the deposited coatings can be divided into three different regions: clad zone (CZ), fusion zone (FZ) and heat affected zone. Equiaxed dendrites appeared in the CZ while columnar dendrites occurred in the FZ, and discrete fine Laves phase particles were formed under low beam current while continuous coarse Laves phase particles were found under high beam current. The EDS results showed that the degree of Nb segregation in FZ is higher than that in CZ. More importantly, the microstructure coarsened and the degree of Nb segregation increased with the increase of beam current. The deposited coating under the lowest beam current (10 mA) has the highest hardness (263 HV0.2) and the minimum specific wear rate (3.95391\u2009×\u200910−15 m3/Nm), which is corresponding to the fine microstructure, discrete Laves phase particles and low degree of Nb segregation under low beam current.