High temperature oxidation behavior of a Fe-Mn-Si-Cr-Ni-Ce shape memory stainless steel

Abstract

Austenitic stainless steels are important engineering materials because they combine good mechanical properties, weldability and excellent corrosion and heat resistance. These alloys are widely used in the chemical processing and energy production involving the exposure to high temperatures ranging from 600 to 900 °C. However, austenitic stainless steels are expensive because they contain high content of expensive Ni element. Especially in recent years, the price of Ni had increased a lot, signicantly limiting their applications. In this context, high manganese austenitic stainless steels containing less expensive Ni element have attracted much attention recently. The newly developed Fe-Mn-Si-Cr-Ni shape memory austenitic stainless steels, containing high Mn contents (13 - 20% wt.%) and a relatively low Ni content (~5 wt.%) when compared to conventional austenitic stainless steel, have showed great promise for constrained recovery applications in various industrial sectors, because they combine unique properties, such as shape memory effect, good mechanical properties and corrosion resistance with low production costs and excellent workability. These alloys are becoming potential candidates for use in various engineering applications, for instance in release devices of satellite solar panels and pipe couplings without welding process. However, since the development of these alloys is relatively recent, many of their properties are still the subject of investigation, particularly their oxidation behavior in aggressive environments such as those faced in the energy production and chemical processing plants. In this work, 4 compositions of the Fe-Mn-Si-Cr-Ni-Ce alloy will be elaborated and their oxidation behavior at 800 °C in air will be characterized for a period of 120 hours. The characterization will be based on optical microscopy (OM), scanning electron microscopy with X-ray microanalysis (SEM/EDS) and X-ray diffraction (XRD) and thermogravimetric analyses. The shape memory effect of alloys will be evaluated by means of bending tests.