High temperature air oxidation behaviour of “poor man” high manganese-aluminum steels

The behaviour of austenitic high manganese (19.8%–32.5%)aluminum (7.1%–10.2%) steels in high temperature air has been examined. Tests have been carried out in the 600–900°C temperature range for durations up to 200 h. The steels form a high manganese scale at high oxidation rates; aluminum does not contribute to the formation of this scale. Only a 1.5% silicon bearing steel shows a good oxidation resistance up to 700°C, the oxidation rate being lower because as shown by XPS analyses a silicon-containing scale is formed. The oxidation resistance of these steels is always lower than that of conventional grades of austenitic stainless steels.     

A study of the behaviour of titanium in acidic solution. Part 1 — Anodic behaviour and behaviour in “ababdoned” conditions

Despite numerous investigations into the corrosion behaviour of Ti and its alloys there are numerous discrepancies in literature with respect to the type of the tetravalent ion formed during the dissolution of titanium in aerated acid solutions; the same applies to the thermodynamical data concerning a possible redox reaction between titanium ions having different valencies. It is for this reason that the authors make an attempt at showing the importance of the formation of tetravalent titanium ions during the spontaneous passivation of titanium in acidic solutions. In this context they start by studying the anodic behaviour of titanium, in order to work out a basis for the evaluation of specimens of different origin. The studies are carried out in aerated and deoxygenated sulfuric acid, with and without external polarization. The anodic behaviour is then interpreted in terms of the mixed potential theory.