that of silicon, the amount of manganese found in the
inclusion is less than that of silicon, while the variation is
found to be similar. Similar behavior in elemental
distribution was found in high-Al steel weld inclusions,
where the cores were found to be richer in aluminum
(Figure 11).
During welding, aluminum present in the liquid weld
pool combines with available atmospheric oxygen and
forms oxides, due to its higher affinity to oxygen
compared with silicon. The formation of aluminum
oxides leads to solute entrapment in its surroundings
and to the subsequent formation of silicon oxides and
epitaxially grown manganese sulfides when the liquid
weld pool cools below the solidification temperature.
The EDS analysis of inclusions in the high-Al steel FZ
(Figure 11) confirms this mechanism, where the aluminum
content is found to be higher at the center core of
the inclusion. In the case of high-Si steel, which contains