Growth Kinetics of Iron Aluminide Layer on Hot-dip Aluminized AISI 304 Austenitic Stainless Steel

Abstract

The hot-dip aluminizing process was performed on AISI 304 austenitic stainless steel at different temperatures and durations. Characterizations of intermetallic layers, e.g., thickness, species and cross-sectional microstructures were performed. Growth kinetics of the intermetallic layer was analyzed by diffusion theory and the Arrhenius equation. It was found that an aluminium and iron aluminide layer, Fe2Al5 phase, were mainly detected for all investigated hot-dip aluminizing processes. The thickness of the iron aluminide layer increased with increasing temperature and time, according to the diffusion theory. The activation energy of 86.51 kJ/mol was determined. Finally, a simulation diagram of the predicted layer thickness as a function of aluminizing temperature and time was constructed. Moreover, to observe and illustrate the phase transformation of the iron aluminide layer, the selected hot-dip aluminized condition was annealed at a temperature of 800 °C for 12 h.