High-Temperature Oxidation Behavior of an Additively Manufactured Alumina-Forming Austenitic Stainless Steel

High-temperature oxidation behavior of an alumina-forming austenitic stainless steel (AFA25) produced by additive manufacturing (AM) has been studied at 850 °C in air and compared to the conventional wrought alloy. The mass gain measurements during high-temperature oxidation tests were performed to understand the rate of oxidation, oxidation characteristics, and morphology of oxides that form in these alloys. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to characterize the microstructure and oxide scale formation during high-temperature exposure. A similar alumina scale was observed on both wrought and AM alloys. The continuous alumina layer that forms in these alloys provides superior oxidation resistance. This paper shows that a variation in AM build parameters influences the oxidation properties, where one AM alloy with a lower laser power to hatch ratio depicts much better oxidation properties compared to conventional wrought AFA alloys.