Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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Resultados da Pesquisa
Artigo de evento 0 Citação(ões) na Scopus Influenzce of the sigma phase formation in pitting potential of UNS s31803 duplex stainless steel in 0,6M NACL AGED at 850 E 900°C(2010-07-26) Daniella Caluscio dos Santos; Rodrigo MagnaboscoThe main purpose of this work is to analyze the mechanisms and kinetics of sigma phase formation of UNS S31803 stainless steel after isothermal aging between 850 e 900°C, evaluating the influence of sigma phase formation on pitting potential in 0.6M NaCl solution. Solution treated samples of the UNS S31803 duplex stainless steel were isotermically aged at 850°C or 900°C up to 360 h. The microstructural characterization of the samples was made through quantitative metallography, ferritscope analysis and Vickers microhardness. The cyclic polarization tests used to the determination of the pitting potential were conducted in polished samples. The electrochemical behavior of aged UNS S31803 duplex stainless steel in 0.6M NaCl solution is strongly dependent on the microstructure, since both changes in mechanisms and kinetics of sigma phase formation influenced the pitting potential of the material. Increasing aging time lead to the decrease of pitting potential, due to the formation of chromium impoverished regions. Oscillations in pitting potential values were noted due to the chromium redistribution enabled by easy diffusion of this element in high temperatures.- Relation Between Pitting Potential and PREN Values for Ferrite and Austenite in Duplex Stainless Steels.(2019-12-12) Daniella Caluscio dos Santos ; MACARRÃO, ISABELLE MONFRINATTI; Rodrigo MagnaboscoThis work aims to investigate the relation between PREN of ferrite and austenite and the pitting potential of UNS S31803 DSS. Samples were solution-treated between 1040 °C and 1150 °C generating different phase fractions and, consequently, different alloy element contents. ThermoCalc® thermodynamic simulations were performed to predict the chemical composition of each phase allowing the PREN calculations. Besides, potentiodynamic polarization tests were conducted in 0.6M NaCl solution at 70 °C to correlate pitting potential (Epit) and PREN. Thermodynamic simulation reveals that PREN for ferrite is higher than austenite between 975 °C and 1300 °C. Nevertheless, the electrochemical results show a slight reduction of pitting potential with increasing ferrite content, probably related to the reduction of Cr and Mo contents in this phase. Pits were found preferably in ferrite and in ferrite/austenite interfaces. This behavior suggests that, even with only a slight reduction of pitting potential and, consequently, a discrete corrosion resistance reduction, ferrite is more susceptible to pitting. No pits were found in austenite, suggesting that higher N contents are fundamental to maintain the corrosion resistance of this phase.