Characterization of Cobalt-Based Stellite 6 Alloy Coating Fabricated by Laser-Engineered Net Shaping (LENS)

The results of microstructure and mechanical properties evaluation of a Stellite 6 (Co-6) alloy deposited on X22CrMoV12-1 substrate by the laser-engineered net shaping (LENS^TM) technology are presented in this paper. The Stellite 6 alloy is widely used in industry due to its excellent wear resistance at elevated temperatures and corrosive environments. Specific properties of this alloy are useful in many applications, e.g., as protective coatings in steam turbine components. In this area, the main problems are related to the fabrication of coatings on complex-shaped parts, the low metallurgical quality of obtained coatings, and its insufficient adhesion to a substrate. The results of recently performed investigations proved that the LENS technology is one of the most effective manufacturing techniques of the Co-6 alloy coatings (especially deposited on complex-shaped turbine parts). The microstructural and phase analyses of obtained Stellite 6 coatings were carried out by light microscopy techniques and X-ray diffraction analysis. A chemical homogeneity of Co-6 based layers and a fluctuation of chemical composition in coating-substrate zone after the laser deposition were analyzed using an energy dispersive X-ray spectrometer coupled with scanning electron microscopy. The room temperature strength and ductility of the LENS processed layers were determined in static bending tests.