Abstract
The isothermal and cyclic oxidation behavior of Haynes 282 (H282) processed by laser powder bed fusion and electron beam melting was compared to its cast counterpart during exposures in air at 800 and 950 ∘C. The specific microstructure of the AM alloys compared to coarse-grain cast 282 resulted in differences in oxidation rates, internal oxidation and spallation behavior. At 800 ∘C, faster Ti diffusion to the surface due to the smaller grain size of the AM alloys led to Ti doping of the Cr2O3 scale and faster oxidation rates. The higher density of grain boundaries also resulted in more pronounced internal oxidation. At 950 ∘C, a duplex Cr2O3 scale was observed with a dense inner layer and porous cracked outer layer with embedded TiO2 particles. The impact of the external and internal oxide compositions and oxidation-induced elemental depletions on the oxidation lifetime, creep properties and spallation behavior is discussed.
