SS420 Pickling and Passivation: Helpful Testing Advice

Summary for ss420 pickling and passivation Discussion

SS420 pickling and passivation is the core issue here: Juan Moreno asks how to remove black burn marks from heat-treated 420 stainless steel drive rollers without mechanical brushing. He explains that after heat treatment the rollers buckle, are straightened with heat, and then show burned black spots that must be brushed to restore the natural finish. He tried nitric acid and hydrofluoric acid, but the parts blackened even more and the stain did not disappear. The only answer shown is from "adv.", who says to contact him directly and notes that they tested a few possible chemical solutions for heat-treated 420 stainless steel. No specific chemical process or guaranteed fix is given in the excerpt, so the thread mainly indicates that the problem may require specialized testing rather than a simple off-the-shelf pickling step.