Characterizing the Structure Evolution of Tertiary Scale during Simulated Coiling by EBSD

Abstract

An oxide scale formed at 900 °C for 60 s in dry air was subjected to the simulated coiling processed with diferent coiling temperatures. The phase transformation behavior, especialy the orientation distribution of the oxide scale, was analyzed using electron backscatered difraction (EBSD) technique. When cooling from the coiling temperature of 650 °C, the scale consists of Fe₃O₄ layer, FeO layer and Fe₃O₄ sam. The Fe₃O₄ precipitates are observed in the FeO grains of the scale formed with the coiling temperature of 550 and 450 °C. With the coiling temperature of 350 °C, the decomposition of FeO is suppressed due to the low temperature. The Fe₃O₄ grains, which are decomposed from FeO, has the same orientation as the parent FeO grains. Moreover, the FeO grains, of which the growth direction is paralel to <001>, is easier to decompose into Fe₃O₄ than the grains with other orientations.