Microstructural and Mechanical Properties of Nickel-Based Superalloy Fabricated by Pulsed-Mode Arc-Based Additive Manufacturing Technology

The additive manufacturing technique has emerged as a prominent primary manufacturing technique on a global scale. Technological advances in the metal additive manufacturing process have made it a potentially revolutionary novel method to manufacture complicated structures in aerospace, energy, and construction industries. In the present study, Hastelloy C-22 thin-wall part was developed using a mechanized pulsed mode wire arc additive manufacturing (WAAM) process. The microstructural and mechanical strength characterization of the additively developed thin-wall part was investigated in the cross and transverse sections. The metallographic structure investigation of both sections revealed the existence of equiaxed, cellular, and elongated dendrites in the top, middle, and bottom regions, respectively. The scanning electron microscope (SEM) with energy dispersive spectrum (EDS) assessment revealed a increases in the concentration of Mo in the inter-dendritic regions of the thin-wall section, in contrast to the dendritic core regions. The pulsed mode process uses an increased cooling rate, which reduces elemental segregation, encourages a improved microstructure, and enhances better mechanical performance. In the electron-backscattered diffraction analysis, the mean grain size is 139.29 µm in the cross-section and 109.30 µm in the transverse section. The volume proportion of higher-angle grain boundaries (HAGBs) is more significant than that of lower-angle grain boundaries (LAGBs), increasing mechanical characteristics. The maximum Vickers microhardness values are attained in the transverse section, with measurements of 311 HV, 304 HV, and 300 HV at the top, middle, and bottom, respectively. Similarly, the mechanical strength also increased in the top region of the transverse section, with an ultimate tensile strength (UTS) of 745 MPa ± 2.80. The fluctuation in mechanical strength can be related to the presence of microstructural heterogeneity. The present research examines the correlation between the microstructural and mechanical properties of a Hastelloy C-22 developed by robust wire arc additive manufactured.

Graphical Abstract