EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Low alloyed steel slabs produced by the continuous casting process can present transverse corner cracks, which cannot be repaired afterwards due to the formation of an oxide layer within the crack. Because of that, the understanding of the formation of these cracks, as well as the reproducibility of the phenomenon through laboratory tests is of great value. The present work analyzed samples taken from the slab corners, where cracks were identified. The fracture surfaces were observed with the scanning electron microscope (SEM) and afterwards the samples were cut to have the microstructure analyzed with the light optical microscope (LOM). By using two different etching methods to reveal the microstructure, it was clearly seen that the cracks were initiated and propagated at the prior austenite grain boundaries. Furthermore, the SEM images from the corner samples were compared to the samples tested by physically simulating the continuous casting process, and the structure found was similar to the ones tested at the critical temperatures. The same was noted for the microstructure analysis, where cracks were also frequently seen at the former austenite grain boundaries. Therefore, it could be concluded that the steel behavior in the laboratory tests done with in-situ melted samples showed to be in good accordance with the reality of the continuous casting process.