Effect of KMnO4 on the HCl-based Pickling Process of 430 Stainless Steel

The effect of potassium hypermanganate (KMnO4) as an oxidant on pickling behavior in HCl-based electrolyte and the surface quality of original hot-rolled and blasted 430 stainless steel (430-SS) plate are studied, using weight-loss tests, microstructure analyses (scanning electron microscope and laser scanning microscope), potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. The results showed significantly accelerated pickling process for 430-SS by adding KMnO4 through enhanced cathodic reaction rate and reduced charge-transfer resistance (Rt). The weight loss rate of 430-SS is 83.6% higher under the condition of 1wt% KMnO4 than that without oxidant, which grows an enormous 2.33 times with KMnO4 content of 2wt%. The 430-SS plate is left as a total clean one without any oxide layers left or any kind of local corrosion, when 1.5wt% KMnO4 is added. KMnO4 can be confirmed as an appropriate oxidant when many factors such as accelerating the pickling process in the process of the pickling, improving the 430-SS' surface quality, solution recycling possibility and environment protection are considered as a whole.