Abstract:
In this work, the influence of the corrosive medium and temperature on the corrosion resistance properties of S31803 duplex stainless steel was evaluated. The corrosive process was carried out using a 1.5% hydrochloric acid solution, at 25, 50 and 80 ° C, which is a typical solution when it is desired to evaluate point corrosion, as it involves chloride ions. The microstructure of the sample as received was analyzed before and after the corrosive process using the techniques of optical microscopy, confocal. Then, mechanical and corrosion resistance tests were performed. The microstructure of S31803 duplex stainless steel is composed of two phases, ferrite and austenite, oriented in the lamination direction, with an approximate balance of 50% in volume of the phase fractions present. The corrosive medium of HCl, at temperatures of 25 and 50 ° C, allowed the development of uniform corrosion and pitting corrosion in the material, which is typical of solutions containing chloride ions. With the increase in temperature to 80 ° C, deterioration of the passive film was observed, significantly increasing uniform corrosion, where it is developed selectively, with ferrite as an anode and austenite as cathode. Samples, when subjected to corrosive media and different temperatures, tend to decrease their values of mechanical properties when they undergo punctiform corrosion. On the other hand, when uniform corrosion was observed in the samples, the tendency was to increase the values of mechanical properties when compared to the initial state.