Steel long-term oxidation

In the present study, the long-term oxidation resistance of some of these FeCrMn(La/Ti) steels in both air and simulated anode gas has been studied and compared with the behaviour of a number of commercially available ferritic steels. Main emphasis was put on the growth and adherence of the oxide scales formed during exposure, their contact resistance at service temperature as well as their interaction with various perovskite type contact materials. 

H. E. Evans and A. T. Donaldson. Silicon and Chromium Depletion During the Long-Term Oxidation of Thin-Sectioned Austenitic Steel. Oxidation of Metals, 50 (5/6) 457-475, 1998. 

Long-term oxidation of steel in air and oxygen follows the parabolic law when the scale remains adherent to the steel, but the oxidation rate of steel is slower than that of pure iron. Generally for steel oxidation, the scale-steel interface adhesion is lost over longer oxidation times and at temperatures above 950°C. 

The presence of small quantities of S in steels has little effect on the initial scaling rates in air, but may be detrimental to long-term scale adhesion. Sulphur has, however, been shown to be detrimental to breakaway oxidation in CO/CO2 environments. However, sulphur has been shown to reduce the total uptake of carbon in the steel under CO/C02 and reduce the scale thickening rate. In this context, free-cutting steels were found to oxidise at a significantly lower rate, as did steels subjected to pretreatment in H2S. 

I0.6.8.I Cladding failure in oxide fuel pins of nuclear reactors. The long-term operational performance of nuclear fuel pins is critically governed by the reactions that occur in the gap between the fuel and its cladding. Ball et al. (1989) examined this for the cases of (1) Zircaloy-clad pellets of U02+, in a pressurised water reactor (PWR) and (2) stainless-steel-clad pellets of (U, P)02+, in a liquid-metal-cooled fast-breeder reactor (LMFBR). In particular they were interested in the influence of O potential on Cs, I, Te and Mo and the effects of irradiation on the gaseous species within the fuel-clad gaps. 

Although originally AISI347 stainless steel seemed a reasonable choice, it was soon shown that it is not suited for long term operation over several years. The best corrosion protection would be provided by materials that can passivate. AISI 316 or AISI 310 stainless steel would in principle provide such a relatively stable and protective oxide scale in the presence of molten carbonate at least under cathodic conditions. 

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