Abstract
An experimental study with respect to the effect of melt superheat on the unidirectional solidified structure of duplex stainless steel (DSS) is reported. The results show that the melt superheat causes distinct modifications of both macrostructure and microstructure of DSS. For macrostructure of DSS, the columnar to equiaxed transition is observed at different melt superheats. The length of equiaxed zone increases and the equiaxed grain size decrease with melt superheat decreasing. For microstructure of DSS, there are significant differences in the morphology of the austenite at intragranular and boundary. In the interior of ferrite grains, the austenite appears primarily as acicular morphology. Nevertheless, the austenite takes on a widmänstatten side plate appearance at the ferrite grain boundaries. In addition, the austenite content increases with melt superheat decreasing.
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