Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
Effect of Pickling Treatment on the Pitting Corrosion of Hyper Duplex Stainless Steel in a Highly Concentrated Chloride Solution
Min-Seok ChoiSoon-Tae KimSoon-Hyeok JeonYong-Soo ParkKwang-Tae KimJi-Soo KimKi-won ParkChang-Man Kim
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2013 Volume 54 Issue 9 Pages 1779-1787


The effect of pickling treatment on the pitting corrosion of hyper duplex stainless steel was investigated in a highly concentrated chloride environment. Increasing the pickling time in 10 vol% HNO3 + 5 vol% HF solutions at 328 K improved the resistance to pitting corrosion by increasing the pitting potential and passive region. There are two primary reasons for the considerable enhancement of the corrosion resistance of the hyper duplex stainless steel pickled for 20 h. First, the oxide scale and Cr-depleted areas which decrease the resistance to pitting corrosion were removed. Second, chromium oxide (Cr2O3), chromium trioxide (CrO3), molybdenum dioxide (MoO2), molybdenum trioxide (MoO3), tungsten dioxide (WO2) and tungsten trioxide (WO3) in an oxide state, chromium hydroxide (Cr(OH)3) and molybdenum oxy-hydroxide (MoO(OH)2) in a hydro–oxide state, chromate (CrO42−) as corrosion inhibitor in an ion state, ammonium (NH4+) elevating the pH in an ion state, and chromium nitride (CrN) acting as a precursor for the formation of Cr2O3 in the nitride state were increased and assisted in improving the corrosion resistance.

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© 2013 The Japan Institute of Metals and Materials
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