Stainless steels constituted of austenitic-ferritic matrix are called duplex stainless steels (DSS). The presence of ferrite and austenite phases simultaneously in similar proportion causes to DSS an excellent arrangement of properties such as high corrosion resistance and high mechanical strength values. The best properties are reached by obtaining an appropriate balance of austenite and ferrite without deleterious phases. However, due to the high presence of alloying elements in its chemical composition, the DSS has a complex behavior of transformation and precipitation phases. During the welding process the phase transformation are influenced by the cooling rate imposed by the thermal cycles associated with the heat input. The purpose of the present work is to evaluate the UNS S31803 (DSS) microstructural transformation behavior and its mechanical properties variations based on different cooling rates from different solubilization temperatures. Four different temperatures were used (1000, 1100, 1200 and 1300 Celsius degrees) followed by cooling in ice water, water at room temperature and oil, which provided cooling rates starting respectively from 228, 98 and 62 Celsius/s degrees. In the test results, the studied DSS proved to have satisfactory response regarding the mechanical limits specified in ASTM A240-2015 for all conditions applied. Furthermore, the variation in the fractions of phases were more significant for solubilization temperatures at 1200 and 1300 Celsius degrees, regardless of the cooling rate applied, which was reflected in the mechanical properties of the steel.