Electrochemical extraction of microalloy carbides in Nb-steel

An electrochemical extraction technique was evaluated as a characterization method of precipitates in microalloyed steels. To carry out this Study, a fully precipitated Nb-modified SAE 8620, was used. The investigation was accomplished by varying the electrolyte composition and the filter pore sizes used to collect the particles. The quantification of Nb was performed by inductively Coupled plasma,atomic emission spectroscopy (ICP-AES). Microscopy examination was also performed on extraction replicas and on residues collected in the acetate fitters. Additionally, X-ray diffraction analysis (XRD) on the collected residues containing the precipitates was accomplished. The results showed that the dissolution rate is faster in the electrolyte consisting of 10 vol% HCl in water. Additionally, transmission electron microscopy (TEM) analysis along With chemical analysis by ICP-AES, showed that (Nb,Ti)C particles were collected in acetate fitters with a pore size much larger than the precipitate size.