parameters by Han et al.[5,6] showed porosity formation
in the weld beads, resulting in poor mechanical properties.
These authors concluded that increasing the speed
of welding and lowering the laser power reduced the
volume fraction of porosity and improved the properties
of the welded material. However, these articles only deal
with mechanical properties of the welded TRIP steels,
and there is no work so far reported on the microstructrual
evolution during welding. The effect of weld
thermal profile and alloying additions on the nature and
volume fraction of microstructural constituents formed
in a given weld thermal cycle should be thoroughly
characterized in order to tailor appropriate weld thermal
cycles.
In the present work, an attempt has been made to gain
more insight into microstructural evolution during
welding of commercially processed silicon- and aluminum-
based TRIP steels. These steels were welded by
means of gas tungsten arc (GTA) welding. The influence
of the weld thermal cycles and composition on the
nature of microstructrual constituents formed in the
HAZ and fusion zone (FZ) after welding were studied.
The role of alloying additions such as silicon and
aluminum on the phase transformation behavior of
TRIP steels during welding was thoroughly analyzed.
Their partitioning behavior in the various microstructrual
constituents that were formed in a given weld
thermal cycle were also studied to understand their role
in RA stabilization and inclusion formation in the FZ of
the welded TRIP steels