Some features of the austenite micro structural evolution have been reviewed at the simulated HAZs (Heat Affected Zones) in a duplex stainless steel. The evolution of the different morphological forms of austenite was quantified in the microstructures for each simulated heat input. A detailed study of the micro structural parameters in the present study, allowed justifying the performance of the volume fractions corresponding to the three austenite morphologies on the HAZ mechanical properties and pitting corrosion resistance. Transmission electron microscopy showed the predominance of specific orientation relationships between the small intragranular austenite precipitates and ferrite considering the nitrogen content in the alloy and the transformation route.