Surface Structure Analysis of Initial High-Temperature Oxidation of SS441 Stainless Steel

Abstract

Chromia-forming ferritic stainless steel (FSS) is a highly promising interconnect material for application in solid oxide fuel cells. In this study, initial oxidation of chromium oxides was performed at 500–800 °C to understand the evolution of materials at an early stage. The structural variations in oxide scales were analyzed through scanning electron microscopy, energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffractometry (XRD), laser confocal microscopy (LSCM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Surface electrochemical properties were investigated through electrochemical impedance spectroscopy to understand how the heat treatment temperature affected surface impedance. Treatment temperatures higher than 700 °C facilitate the diffusion of Cr and Mn, thus allowing ferritic spinels to form on the surface and leading to high electrical conductivity.

Precipitation Kinetics During Post-heat Treatment of an Additively Manufactured Ferritic Stainless Steel

“…[7][8][9] Other than that, AISI 441. is a solid-solution strengthened steel with some alloying additions of Ti and Nb for stabilization and improved high-temperature strength. [8,9] Previous work has shown that AM of AISI 441 by laser-powder bed fusion (L-PBF) lead to excellent mechanical properties compared to the conventional material produced by casting and hot rolling, attributed to the finer structure with small grain size in the printed material. [12] Conventionally manufactured AISI 441 is usually used in the hot or cold rolled and heat-treated state.…”