Effect of dew point and gas flow rate on the surface oxidation of Advanced High Strength Steels

Il Ryoung Sohn, Jong Sang Kim, Seetharaman Sridhar

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The chemical and morphological features of oxides, at or near a steel surface, greatly influence the formation of the inhibition layer, critical for controlling the quality of the coating during immersion into the Zn bath. The oxides influence the wettability and the final composition of the Fe-Zn alloy coating. In this study, oxidation behaviors of Advanced High Strength Steels (AHSS) are studied during annealing in a H2-5%N2 atmosphere with controlled dew-points (0 to -40°C) and gas flow rates (5 to 100 l/min.). Compact external oxides, with a high SiO2, Al2O3 ratio, were found to form on the steel surface when the dew point was low and/or the gas-flow rates high. As dew points were increased and gas-flow rates decreased the surface oxides became less continuous and the presence of internal oxides became substantial. The influence of gas-flow rate cannot be attributed solely to the gas phase transport of oxidants to the metal surface and it is suggested that the equilibration state of the gas and consequent amount of molecular oxygen present near the surface needs to be considered.

Original languageEnglish (US)
Pages (from-to)2008-2017
Number of pages10
JournalISIJ International
Volume55
Issue number9
DOIs
StatePublished - 2015
Externally publishedYes

Keywords

  • Annealing
  • High Strength
  • Non-equilibrium state
  • Oxidation
  • Oxide
  • Steel

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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