Effects of H2O2 and temperature on electrolytic pickling of austenitic stainless steel 304L in Na2SO4 solution

Abstract

The effects of H2O2 solution addition and temperature on electrolytic pickling via Na2SO4 solution to eliminate the metal oxide layers of an annealed 304L stainless steel were investigated by polarization technique. The experimental conditions involved a pure 190 kg × m-3 Na2SO4 solution and a mixture of 190 kg × m-3 Na2SO4 + 10 kg × m-3 H2O2 at 298, 318 and 333 K and pH 4. It was found that the addition of a 10 kg × m-3 H2O2 solution in 190 kg × m-3 Na2SO4 solution and an increase in temperature resulted in a decrease in the passive region of the polarization curves. The results from the SEM images, the XRD patterns and root-meansquare roughness showed that the surface of the annealed 304L stainless steel was smoother and fewer remaining oxide scales was found when pickling in 190 kg × m-3 Na2SO4 + 10 kg × m-3 H2O2 solution. However, no effects of the addition of 10 kg × m-3 H2O2 solution in 190 kg × m-3 Na2SO4 solution and temperature on pickling time at 298, 318 and 333 K were observed.