Estudo do Efeito da Temperatura e do Tempo de Tratamento Térmico na Corrosão Localizada do Aço Inoxidável Duplex uns S31803

Abstract

This study aims to evaluate the influence of time of exposure to certain temperatures on the mechanical properties and resistance to localized corrosion of duplex stainless steel UNS S31803. The tested specimens were obtained from ribbons of stainless steel, and treated at temperatures of 475ºC, 570°C, 645°C, 820° C, 914°C and 960°C. For each temperature, samples were heat treated at different times of 4, 8 and 12 hours respectively. Samples provided "as received" were also evaluated.Testing double loop electrochemical potentiokinetic reactivation (DL-EPR) were performed and Testing the hardness and metallographic analysis, which allowed us to evaluate the proportion of microconstituents varied over time and according to the treatment temperature were performed. Furthermore, only the samples exposed for 12 hours at each temperature,were evaluated by X-ray diffraction.The experimental results showed that secondary phases arise at different treatment temperatures and have direct influence on increasing the hardness of steel. For resistance to localized corrosion, only samples undergoing treatment at temperatures of 645, 820 and 914 °C showed a peak of reactivation.