Fusion-Based Additive Manufacturing of Hastelloy C-Series: A Comparative Study on Microstructure, Mechanical Properties, and Residual Stress

The fusion-based single pulsed gas metal arc welding (SP-GMAW) additive manufacturing (AM) process has attracted considerable attention because of its high production efficiency, elevated deposition rates, and near-net-shape capabilities. The present study presents a comparative investigation of Hastelloy C-276 and Hastelloy C-22 thin-walled components fabricated using a SP-GMAW based AM process. This study thoroughly investigates the microstructure, material properties, and residual stress of the components. The microstructures in various regions comprise dendrite structure in Hastelloy C-276 and C-22 superalloys. The Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM/EDS) analysis revealed a discrepancy in elemental composition between C-276 and C-22 materials. Additionally, the average grain size in the top, middle, and bottom portions of C-22 are <inline-formula> <tex-math notation="LaTeX">$67.8~\mu $ </tex-math></inline-formula>m, <inline-formula> <tex-math notation="LaTeX">$78.6~\mu $ </tex-math></inline-formula>m, and <inline-formula> <tex-math notation="LaTeX">$87.6~\mu $ </tex-math></inline-formula>m while C-276 has <inline-formula> <tex-math notation="LaTeX">$72.5~\mu $ </tex-math></inline-formula>m, <inline-formula> <tex-math notation="LaTeX">$80.2~\mu $ </tex-math></inline-formula>m, and <inline-formula> <tex-math notation="LaTeX">$96.8~\mu $ </tex-math></inline-formula>m, respectively. Compared to the build direction, the travel direction has a higher mean microhardness. Hastelloy C-22 achieves a maximum hardness of 320 HV, while Hastelloy C-276 has a hardness of 286 HV. The highest recorded tensile strength for Hastelloy C-22 was <inline-formula> <tex-math notation="LaTeX">$772~\pm ~5.1$ </tex-math></inline-formula> MPa, whereas Hastelloy C-276 displayed a tensile strength of <inline-formula> <tex-math notation="LaTeX">$758~\pm ~4.1$ </tex-math></inline-formula> MPa in the upper regions along the travel direction. According to the stress distribution, the as-fabricated specimens of Hastelloy C-276 and C-22 are mostly impacted by tensile residual stress. Research on Hastelloy C series alloy comparisons and single pulsed GMAW-based WAAM technologies is limited and progressing. The comparative results of this research will be significant in the chemical-based, nuclear energy, maritime, and manufacturing industries.