Effect of C content on the microstructures and mechanical properties of laser additive manufactured Ni-base superalloys

In this study, we fabricated a Ni-base superalloy with three different carbon contents using laser metal deposition (LMD) and systematically investigated its microstructure and mechanical properties. The characterization results showed that carbides precipitated along the grain boundaries in the additive manufactured alloys, the amount increased with the carbon content, and the residual stress reduced with the carbon content. In addition, carbide precipitation was mainly MC (M is mainly Ti, Ta). These samples exhibited excellent mechanical properties compared to the cast samples. Rupture tests conducted at 760 °C/780 MPa indicated that the high carbon content in the additively manufactured alloy affected the rupture life, with the medium-carbon additive manufactured alloy exhibiting better mechanical properties than the other carbon content.