Morphology of Al₂O₃inclusions formed at Fe/Fe–Al interface

Abstract

Inside a silica tube, a piece of Al was brought in contact for a very short time (1-60 s) with liquid Fe containing different dissolved oxygen (O) levels (170-1800 ppm) at 1600uC. The purpose was to investigate the inclusion formation during the initial deoxidation period. Intermetallic compounds of the Fe-Al system appeared due to the interdiffusion of Fe and Al, and the reaction between Al and O at the interface gave rise to the formation of Al 2 O 3 inclusions. These inclusions showed different characteristics according to the initial O level in liquid Fe and the interaction time. With lower O content, the amount of inclusions decreased and faceted particles were dominant among the morphologies. While increasing the O content to 780 and 1800 ppm, the inclusion number increased drastically and numerous small spherical inclusions were observed. Further away from the reaction front, clusters of fine particles were formed through a collision-coagulation mechanism. The change in Al 2 O 3 morphology with the initial O content was interpreted as a consequence of different supersaturation degrees with respect to Al and O.

Some aspects of alumina created by deoxidation and reoxidation in steel

“…The alumina particles, which formed in the liquid steel, appear in various sizes and shapes. [1][2][3][4][5] Deoxidation may create small particles that can agglomerate into a cluster, [6][7][8][9] but clusters can be formed as well by alumina growing into dendrites. The growth of clusters and rod-like particles was observed in steel plant samples where spatially oriented clusters and particles were formed after the steel was killed at the RH-OB installation.…”

Sliver defects in an ultra-low carbon Al-killed steel caused by low steel level in the tundish

“…According to some researchers [27,28], the variation of morphology may be related to different levels of local aluminium and oxygen activities in the liquid bath, as well as reaction time. Also, from the literature [29,30], alumina clusters can be generated by the agglomeration of small alumina particles formed during the deoxidation process or the reoxidation phenomenon. Tiekink et al [27] found various rough clusters of alumina in Al-killed steel intentionally reoxidized by air.…”

CARACTERIZAÇÃO DE INCLUSÕES NÃO METÁLICAS EM UM AÇO ULTRA BAIXO CARBONO ESTABILIZADO AO Ti E DESOXIDADO AO Al

“…134 clusters of alumina were also found as shown in figure 6, along with an elementary map. Small particles of alumina are formed during deoxidation which can agglomerate creating clusters [21,22]. Tiekink et al (2010) found various rough clusters of alumina in a steel intentionally reoxidized by air revealing that clusters can be an evidence of reoxidation.…”