Microstructure and mechanical properties of Inconel 625 components deposited by pulsed plasma arc rapid prototyping

The microstructure and mechanical properties of Inconel 625 component deposited by pulsed plasma arc rapid prototyping were investigated. The precipitation principle and distribution characteristics of phases in deposits were analyzed. The results indicated that the as-deposited samples exhibited homogenous cellular dendrite structure in nature, which grew epitaxially along the deposition direction. The microstructure of the interface regions between deposited layers exhibited refined structure. The composition distribution in the whole sample was pretty uniform and no significant segregation occurred. Some intermetallic phases such as Laves phase, some minor MC (NbC, TiC) and needle-like δ (Ni₃Nb) were observed in γ-Ni matrix. Disperse MC particles precipitates in interdendritic and grain boundary. Micro-hardness measured at various location (including transverse plane and longitudinal plane) revealed hardness in the range of 260-285HV_0.2. Due to highly refined structure, micro-hardness at the interface region is slightly higher than the other regions. Ultimate tensile strength of Inconel 625 sample deposited as short raster pattern was found to be 750MPa, and the percentage elongation was found to be 50%.