Decapado de un acero inoxidable austenítico mediante mezclas ecológicas basadas en H<sub>2</sub>O<sub>2</sub> - H<sub>2</sub>SO<sub>4</sub> - iones F<sup>-</sup>

Abstract

This study reports the pickling of 316L stainless steel using mixtures of hydrogen peroxide (H 2 O 2 ), sulphuric acid (H 2 SO 4 ) and fluoride ions as hydrofluoric acid (HF), sodium fluoride (NaF) and potassium fluoride (KF). The decomposition of H 2 O 2 in the mixtures was assessed at different temperatures 25 °C to 60 °C, with ferric ion contents from 0 to 40 g/l. According to the results obtained, were established the optimal condition pickling at 20 g/l of ferric ions, 25 °C and p -toluensulphonic acid as stabilizer of H 2 O 2 . The HF pickling mixture was the only capable to remove totally the oxide layer from the 316L stainless steel after 300 s. The fluoride salts pickling mixtures only remove partially the oxide layer (20 to 40 % aprox.) after 300 s. When the pickling time was increased until 1200 s, the removal percentages were around to 80 %.