Abstract

GINES, M.J.L. et al. Study of the picklability of 1.8 mm hot-rolled steel strip in hydrochloric acid. Lat. Am. appl. res. [online]. 2002, vol.32, n.4, pp.281-288. ISSN 0327-0793.

 After the hot rolling process the steel strip remains covered with an oxide layer (scale) which must be removed previous to the cold rolling process. The scale removal through the pickling process by hydrochloric acid (HCl) depends on both the scale structure and the conditions of the pickling bath (temperature, acid concentration, and dissolved iron concentration). This work is focused on picklability (decapability) studies accomplished in laboratory on hot-rolled steel strip, 1.8 mm thickness. The oxide amount was determined by weight difference of samples with and without acid pickling. The scale was characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The pickling or descaling time (t_d) was determined using different bath conditions. Pickling kinetic studies were carried out being the pickled fraction (a) determined as a function of the immersion time. Expressions were obtained, allowing descaling time estimation under various pickling bath conditions. These expressions were used to estimate the maximum operation line speed that assures a complete descaling.

Keywords : Pickling; Hydrochloric acid; Oxide scale; Hot-rolled strip; Descaling.

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