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Microscopía de fuerza atómica aplicada a la cuantificación de nanoprecipitados en aceros microaleados al nb-v-ti tratados térmicamente

Abstract:

The aim of this study was to examine de applicability of atomic force microscopy (AFM) to the analysis of precipitate sizes in microalloyed steels, heat treated at different heat treatment conditions. To carry out the study, samples of a commercial Nb, V, Ti microalloyed steel slab were used, in both the as-cast condition and after austenitizing at 1250 ° C at different heating sequences, followed by quenching, For comparison purposes, the precipitates were also characterized by transmission electron microscopy (TEM). The metallographic technique that includes grinding, polishing and etching was followed to prepare the samples for the AFM analysis, while the transmission electron microscopy was conducted upon precipitates removed from the matrix by chemical dissolution. The characterization by AFM revealed the precipitates in the bulk sample. The statistical analysis of precipitates size showed nanometric particles in similar size ranges to those obtained by TEM. Additionally, the AFM analysis allowed to distinguish the variations of precipitates sizes, depending on heating conditions. The results evidenced that the atomic force microscopy is a suitable technique for the analysis of precipitates sizes in micro-alloyed steels. Additionally, it has the advantage of conducting the analysis on samples prepared though conventional metallographic techniques, which are easier compared to the preparation of thin films or particle extraction by matrix dissolution required for the characterization by TEM.