Influence of Cr Content on the Mechanical, Oxidation, and Electrical Properties of Powder Metallurgy Ferritic Stainless Steel for Solid Oxide Fuel Cell Interconnect

Abstract

This study aims to investigate the influence of Cr content on the high-temperature mechanical, oxidation, and electrical properties of powder metallurgy ferritic stainless steel for solid oxide fuel cell (SOFC) interconnect. To achieve this objective, ferritic stainless steel water-atomized powders with different Cr content were first compacted and then sintered at 1380 °C for 2 h under hydrogen atmosphere. The properties were evaluated through high-temperature tensile tests at 800 °C, oxidation tests, and area-specific resistance (ASR) measurements. Microstructural characterization was conducted using x-ray diffraction (XRD), scanning electron microscope (SEM) with energy-dispersive spectroscope (EDS). The results indicated that with an increase in Cr content, the strength of the powder metallurgy ferritic stainless steel specimens increased, while the elongation decreased at 800°C. Additionally, oxidation mass gain decreased, and ASR decreased. Commercially available ZMG232 ferritic stainless steel was employed for high-temperature mechanical, oxidation, and electrical properties comparison. Compared to ZMG232, the high-temperature yield strength and tensile strength of powder metallurgy ferritic stainless steel specimens were higher with 22 wt.% and 26 wt.% Cr content. And with 17 wt.% Cr content, there was a significant difference in oxidation mass gain and ASR. However, with 22 wt.% and 26 wt.% Cr content, oxidation mass gain and ASR were relatively close, indicated that the high Cr content powder metallurgy ferritic stainless steel in this study can be an alternative to the commercially available ZMG232 ferritic stainless steel.