Long-Term Cyclic Oxidation Performance of High-Temperature Alloys in Still Air at 982°C

摘要

The durability and reliability of high-temperature components is critically linked to long-term cyclic oxidation performance of the alloy. There are several factors such as temperature, thermal cycling frequency, and still or flowing environmental conditions that can influence long-term oxidation performance of high-temperature alloys. Of particular importance, in this study, is long-term oxidation performance of alloys exposed for 360 days in still air for relatively short thermal cycle length (once-a-week) than previously reported in the literature. The alloys selected for this study are N07214, N06230, N06617, N06002, N08120, N08811, N12160, R30188, R30556 and N06625. Alloy performances were ranked by assessing weight-change behavior and metal recession measurements which includes metal loss, average internal penetration, and maximum internal penetration. It was found that the alumina-forming N07214 outperformed rest of the alloys, and N06230, N06617, and R30188 were among the best performing chromia-forming alloys. The types of oxide scales evolved and Cr depletion behavior were studied using SEM equipped with EDS. In this paper, effect of thermal cycle length (weekly vs. bimonthly thermal cycling) on the long-term oxidation performance of selected high-temperature alloys was also studied. It was found that increase in thermal cycling frequency adversely affected long-term oxidation performance of certain high-temperature alloys.