State analysis of oxide scale on steel plate surface by electron probe micro-analyzer

The state of standard sample and test steel plate was analyzed by electron probe micro-analyzer(EPMA). The results showed that EPMA could effectively evaluate the various valence states of Fe in oxide scale on steel surface. The comparison method of L_β/L_α peak intensity ratio of Fe element was the most practical. This ratio was compared with the L_β/L_α peak intensity ratio of Fe inreference materials, then,the state of Fe at various positions in oxide scale of test sample could be evaluated. Thus, the identified phases were Fe₂O₃, Fe₃O₄, FeO or pure Fe. After several tests, the L_β/L_α peak intensity ratio of Fe in Fe₂O₃, Fe₃O₄, FeO and pure Fe was 0.36, 0.41, 0.47 and 0.08, respectively. The maximum statistical uncertainty was 0.02. Based on the difference of L_β/L_α peak intensity ratio of Fe, the phase in various gray regions of scale in sectional sample could be identified by EPMA. Moreover, the state of oxide scale defect on sample surface could also be analyzed.