Liquid Al2O3-CaO-MgO inclusion entrapment at delta ferrite intercellular boundaries during solidification

Y. Wang, S. Sridhar

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

The behaviour of liquid Al2O3-CaO-MgO inclusions at the δ ferrite/melt interface in aluminium killed and calcium treated steel has been observed in situ using a confocal scanning laser microscope equipped with a gold image furnace, Movement of inclusions parallel to the solid/melt front was observed (a) during solidification rates below 1 μnm s-1 or with nearly static fronts, (b) during remelting of the front or (c) when inclusions at the solid/melt interface were pushed by a newly arriving liquid inclusion. Upon sliding, the inclusions tended to become entrapped in the intercellular regions of the front. After entrapment, a critical solidification velocity for pushing/engulfment was measured and compared with corresponding experimental results for pushing/engulfment at planar fronts. Engulfment at the intercellular boundaries occurred at solidification velocities larger than a critical velocity Vcr = 9.91 × 10-9R-1/2 in the present study. The result follows the same trend with respect to inclusion size as that found for planar interfaces, but indicates that the critical velocity is ∼20%. lower. This is attributed to the observation that engulfment at intercellular regions involves replacing a section of the intercellular boundary with the inclusion, which decreases the surface energy change owing to engulfment compared with engulfment at planar fronts.

Original languageEnglish (US)
Pages (from-to)223-228
Number of pages6
JournalIronmaking and Steelmaking
Volume30
Issue number3
DOIs
StatePublished - Jun 2003
Externally publishedYes

ASJC Scopus subject areas

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

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