Oxidation and Neutral Electrolytic Pickling Behavior of 304 and 430 Stainless Steels

304 및 430 스테인레스 강판의 산화 및 중성염 전해산세 거동

  • Kim T. S. (Facility & Automation Research Team, RIST) ;
  • Park Y. T. (Cold Rolling Facility Engineering Team, POSCO E&C)
  • 김태수 (기전자동화연구팀, 포항산업과학연구원) ;
  • 박용택 (냉연팀, 포스코건설)
  • Published : 2004.08.01

Abstract

Oxidation behavior of 304 and 430 stainless steel were studied using thin film X-ray analysis and glow discharge spectrum analysis (here-after GDS). The oxidation layer of 304 stainless steel was composed of $Cr_2O_3\;and\;FeCrO_4$ and its thickness was about $1.5{\mu}m$ after $1\~5$ minutes of annealing at $1120^{\circ}C$ open air. However, the oxidation layer of 430 stainless steels was mainly composed of $Cr_2O_3$ and its typical thickness was 0.5um after $1\~5$ minutes of annealing at $1000^{\circ}C$ open air. Electro-chemical analysis revealed that the descaling of oxidation layer could be activated by Fe, Cr dissolution from the matrix behind the oxidation layer at the current density of $5\~10ASD$ and by Fe, Cr-oxide dissolution from the oxidation layer at the current density over than 10ASD. Electrolytic stripping of 430 and 304 revealed the intial incubation period of descaling by oxygen evolving at low current density range such as $5\~10ASD$. However the dissolution of oxide layer was occurred when applying the anodic current of $10\~20ASD$ on 430 and 304 stainless steels. It was suggested that the electrolytic pickling of high Cr bearing stainless steel such as 430 and 304 seemed to be the more effective in the high current density range such as $10\~20ASD$ than the low current density range such as $5\~10ASD$.

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