430不銹鋼在Na2SO4水溶液中之電解除銹研究

Electrolytic Pickling of 430 Stainless Steel in Na2SO4 Solution

本研究分析熱軋及經過後熱處理（post heat treatment, PHT）之430不銹鋼的銹皮性質，並探討在電解除銹時的電化學特性以及除銹效果。後熱處理是在800℃的氮氣中處理30分鐘。電解除銹是在70℃不同pH值的15 wt.% Na2SO4水溶液中於不同之電位（1.5 ~ 1.7 VSCE）下施行。XRD分析結果顯示熱軋及經過後熱處理兩者試片表面的氧化物為Cr2O3及（Fe,Cr）3O4。電解除銹的試驗結果顯示：降低電解液的pH值以及提高電解除銹時的電位，皆可以提升除銹的效果；但是熱軋後熱處理則會增加銹皮電解除銹的困難。銹皮之化學組成與微觀結構對電解除銹效果的影響也加以討論。

The properties of scales formed on hot-rolled 430 SS, with and without post heat treatment (PHT), were investigated. Post heat treatment was carried out in argon at 800 ℃ for 30 minutes. Electrochemical characteristics in pickling bath and the corresponding pickling efficiency of as-rolled and heat-treated 430 SS were also explored. Electrolytic pickling was accomplished at various applied potentials (1.5 ~ 1.7 VSCE) in 15 wt.% Na2SO4 solution with different pHs. X-ray diffraction (XRD) patterns showed that scales of the as-rolled 430 SS consisted of Cr2O3 and (Fe,Cr)3O4. The experimental results showed that improved electrolytic pickling performance could be obtained in the electrolytes with low pH and at much higher anodic potentials. However, post heat treatment had adverse effect on electrolytic pickling of the as-rolled 430 SS. The roles of chemical composition and microstructure of the scale on electrolytic pickling performance were discussed.