VERFAHREN ZUM BEIZEN VON ROSTFREIEN STÄHLEN OHNE SALPETERSÄURE UND IN ANWESENHEIT VON CHLORIDIONEN

摘要

Process for pickling stainless steel carried out at a temperature of between 20 DEG and 70 DEG C, with the use of a pickling solution containing the following basic ingredients: H2SO4 (free acid) : 50 to 200 g/l HF (free acid) : 0 to 60 g/l F<-> anion (total) : 5 to 150 g/l SO4<2-> anion (total) : 50 to 350 g/l Total free acidity (H2SO4 + HF) : between 1 and 7 g. equiv./l where by "free acid" is meant the acid that does not constitute the anion bound in the form of salts or complexes with the metal cations present in the solution; and, in addition: Fe<3+> in a quantity of at least 15 g/l chloride anion in a quantity of between 0.1 and 10 g/l, into which solution is fed, during the pickling process, an oxidant that is able to oxidize Fe<2+> to Fe<3+> in order to maintain the redox potential of the solution at a value of between + 230 and + 800 mV.