塩化ナトリウムおよび硝酸ナトリウム水溶液中におけるＳＵＳ４３０鋼の電解脱スケール

Abstract

This study has been made as a part of studies of electrolytic descaling of iron and steel in neutral electrolytes. In this report the descaling conditions of annealed SUS 430 steel and tis behaviour in electrolytes of sodium chloride and sodium nitrate were experimentally investigated. Results obtained are given in the following: In NaCl electrolyte, no dissolution of the scales on the steel was found, but some parts of the metal substrate exposed to the electrolyte through some scale defects dissolved in the electrolyte. Therefore, layers of the scales were removed by means of separating from the base metal during the electrolytic descaling process. In NaNO3 electrolyte, layers of the scales were removed by the dissolution of a Cr-oxide of the scale during the electrolytic descaling process. In the NaCl solution, a large number of pits were formed by Cl- ions on the descaled parts of the surface of the steel with no glossy appearance, while, in the NaNO3 solution, less pits were formed on the descaled surface. The surface in the latter solution had a well descaled glossy appearence at high temperatures.