The purpose of this work was to evaluate the microstructural alterations associated to the aging thermal treatments performed at 450, 475, 800 and 850°C, for 1, 3 and 12h, besides evaluating the influence of the precipitation of the alpha line phase on corrosion resistance. The samples were characterized by scanning electron microscopy, energy dispersion spectrometry, X-ray diffraction, feritscope, hardness, microhardness, in addition cyclic potentiodynamic polarization and double loop electrochemical potentiokinetic reactivation. In the agings performed at 450°C for 1h and 475°C for 12h, there was precipitation of the alpha line phase inside the ferrite and there was no significant effect on the resistance to pitting corrosion and the phenomenon of sensitization was not promoted. In the aging at 800 and 850°C for 1, 3 and 12h, the sigma phase was formed from the consumption of ferrite, and in the aging at 850°C there was the precipitation of the chi phase, promoting the increase in steel hardness. In agings for 12 h at 800 and 850°C, there was resistance to pitting corrosion decrease and the phenomenon of sensitization was moderated promoted at 800°C, with just the sigma phase precipitation and promoted at 850°C with sigma and chi phases precipitation.

Austenitic stainless steels processed by rolling are widespread in technological applications, since they have excellent mechanical and corrosion properties. This study investigated the effect of the cooling rate, microstructure and properties of 316L austenitic stainless steel under cold rolled conditions and by rapid solidification. The microstructure of the cold rolling processing steel was composed of austenite and a low percentage of delta ferrite. For the rapid solidification condition, the microstructure evolved from columnar and acicular dendrites to equiaxed dendrites with decreasing cooling rates, without the presence of delta ferrite due to the high cooling rate. Furthermore, thermal analyses in both routes revealed that oxidation kinetics was slower after rapid solidification in synthetic air. The microhardness in the cold rolling condition was lower than in the rapid solidification condition since the microstructure under the solidification condition is more refined. The sample in the rapid solidification condition region RS1 presented the highest corrosion resistance considering the pit potential. The passivation current density in the cold rolled condition was 5.72x10-5A/cm2, while under the rapid solidification condition, regions RS1 and RS2 were 2.24x10-5 A/cm2 and 3.72x10-6 A/cm2, respectively, and region RS3, did not present a passivation region in a broad range of potentials.