Effect of Electropolishing Conditions on the Outgassing Properties of Stainless Steel Surface Electropolished by Wiping and Immersion Methods

Abstract

The effect of electropolishing conditions on the outgassing properties of austenitic stainless steel (SUS316L) electropolished by a wiping method (WiEP) and an immersion method (ImEP) was investigated using thermal desorption spectroscopy. In the case of electropolishing by the WiEP in which the metal surface was wiped with an electrolyte-solution-impregnated felt wiper cathode, the SUS316L surface became smoother and the amount of outgassing decreased as the applied voltage (4-8 V) increased. In the case of electropolishing by the ImEP, the SUS316L surface became smoother and the amount of outgassing decreased as the current density (8-15 A dm −2 ) increased. After electropolishing by the WiEP at higher applied voltages and the ImEP at higher current densities, diffusible hydrogen desorbed from the SUS316L surface below 723 K was almost completely removed, however most of the non-diffusible hydrogen remained. These results suggest that the migration of diffusible hydrogen to the SUS316L surface is enhanced by the increase in the applied voltage of electropolishing.