The Role of Discontinuous Precipitation in Metal Dusting

摘要

A high-performance commercial alumina-forming Ni-base alloy was studied after a two years field exposure at 540℃ in a methanol plant. Comparative laboratory studies were performed at 650℃ using a different synthesis gas mixture with the composition; 50%CO + 3%H_2O + 47H_2. Post exposure metallographic examinations with LOM, FEG-SEM, SEM-EDX analysis as well as thermodynamic calculations were made in order to identify and describe the metal dusting mechanisms. An estimate of the metal dusting corrosion rates was performed based on metallography and these were correlated to a theoretical model based on diffusion processes.