Effects of Co and Nb on the Crack of Additive Manufacturing Nickel-Based Superalloys

Increasing the print quality is the critical requirement for the additive manufactured complex part of aero-engines of nickel-based superalloys. A study of the effects of Co and Nb on the crack is performed focusing on the selective laser melting (SLM) nickel-based superalloy. In this paper, the solvus temperature of γ ', crack characteristics, microstructure, thermal expansion, and mechanical properties of SLM nickel-based superalloy are investigated by varying the content of Co and Nb. The alloy with 15Co/0Nb shows the highest comprehensive quality. Nb increases the crack risk and thermal deformation, and then Co accelerates the stress release. Therefore, Co is an extremely important alloying element for improving the quality of SLM nickel-based superalloy. Finally, the crack growth kinetics and the strain difference are discussed to reveal the SLM crack regular that is affected by time or temperature. The analysis work on the effect of alloying elements can obtain an effective foundational theory to guide the composition optimization of SLM nickel-based superalloys.