High-temperature oxidation of pure Fe and the ferritic steel 2.25Cr1Mo

Abstract

The global pressure for recycling and ecological energy production increases steadily in combination with the demand of cost-effective application of materials. However, some severe corrosion problems, associated with the high internal/intergranular corrosion rates in boiler components need to be avoid. Some commercial boiler materials contain a Cr content of 0.55 (wt. (%)) - 2.25 (wt. (%)). This Cr concentration in the alloys is not sufficient for the formation of a complete dense Cr2O3 scale. Hence, high oxidation kinetics may result. In this study, pure Fe and the steel 2.25Cr1Mo were oxidized in laboratory air at 550 °C using a thermobalance system. The surface as well as the cross section of oxidized specimens were analysed using scanning electron microscopy in order to quantify several factors (e.g. surface finishing, cold working and grain size) on the overall oxidation kinetics. For alloys with low Cr content, a decreasing in the grain size leads to an acceleration of the oxidation rate by facilitating the oxygen diffusion along alloy grain boundaries leading to an inward oxide layer formation. The study of effects of surface finish and cold working yielded results revealing that the oxidation process is complex and comparison of results from different laboratories is difficult and should be done

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

“…It is strengthened by the addition of Nb, Ti and Mo. Whereas, its good oxidation resistance is provided by a high chromium content & (17)(18)(19)(20)(21) wt.%, that allows the development of a protective surface chromia scale in most atmospheres [3][4][5].…”

“…One way of modifying the oxidation behaviour of an alloy is through the use of a surface treatment such as polishing, electro-polishing, grinding, shot peening, sandblasting, machining or cold rolling. The effect of surface treatments on oxidation have been studied previously [14][15][16][17][18]. As a result of surface treatment, energy is stored in the surface region of a metal in the form of dislocations [19,20].…”

High Temperature Oxidation Behavior of Fe-Cr Steel in Air at 1000-1200 K

“…This implies that grain boundaries become preferential site for oxide nucleation. According to literature study [15] in low-alloy steel, the steel grain size should play an importance role on the diffusion controlled oxidation behavior because in polycrystalline materials, the reactive element is easily to diffuse through the grain boundaries. The result obtained in present study is similar to the previous study that the steel surface is oxidized from grain boundaries to form spinel oxide and Cr2O3 phases [16].…”

High Temperature Corrosion Behavior of Cold Deformed 2.25 Cr-1 Mo Steel in SO2 + O2 Atmosphere

“…Trindade et al [2] have reported that oxidation rate decreases with the increase in percentage of cold deformation. Kaur and Gust [3] have concluded that cold deformation provides faster diffusion paths (dislocation pipe) in the specimen, which results decrease in corrosion rate.…”