Structure and Properties of Cobalt-Based Superalloys After Electron Beam Additive Manufacturing

The paper examines the structuel formation and its impact on the mechanical properties of cobalt-based superalloy samples, namely Stellite 6 and Stellite 12, produced via wire-feed electron beam additive manufacturing (EBAM). It is demonstrated that this method enables the product fabrication from cobalt superalloys without macroscopic defects. It is shown that the primary phase and structural components of the EBAM-processed samples are dendrite arms comprising a cobalt-based solid solution, two types of carbides (M₇C₃ and MC), and eutectics distributed in the interdendritic space. The mechanical properties of the Stellite 6 alloy sample are superior to those of the Stellite 12 sample due to the martensitic γ-Co → ε-Co transformation in the former.