Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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2 resultados
Resultados da Pesquisa
- Corrosion versus mechanical tests for indirect detection of alpha prime phase in UNS S32520 super duplex stainless steel(2011-04-05) FONTE, T. F.; Rodrigo Magnabosco; TERADA, M.; PADILHA, A. M.; COSTA, I.Alpha prime formation leads to material embrittlement and deterioration of corrosion resistance. In the present study, the mechanical and corrosion behavior of super duplex stainless steel UNS S32520 aged at 475°C from 0.5 h to 1,032 h was evaluated using microhardness measurements, Charpy impact tests, electrochemical impedance spectroscopy, and cyclic polarization curves. The sensibility of these tests to the effects of alpha prime phase was investigated. The microhardness test showed a gradual increase in hardness with aging time, whereas the impact tests revealed losses of about 80% in the energy absorption capacity for the material aged for 12 hin comparison with the solution-annealed samples. The most responsive analysis was the impact test, which indirectly revealed the presence of this deleterious phase in samples aged for 0.5 h. The electrochemical impedance spectroscopy and polarization tests were not highly sensitive to the alpha prime phase unless these are present In large amounts in the stainless steel. © 2011, NACE International.
- On the Interaction between Uniaxial Stress Loading and the Corrosion Behavior of the ISO 5832-1 Surgical Stainless Steel(2021-04-05) SANTOS, R. C. F. DOS; NAVILLE, W.; LIMA, N. B. DE; COSTA, I.; ANTUNES, R. A.© 2021, ASM International.The interaction between the uniaxial stress loading and the corrosion behavior of the surgical ISO 5832-1 stainless steel is addressed in the present work. Specimens were subject to uniaxial tensile and compressive stress at two different deformation levels (15 and 30%). The effect of the different loading modes and deformation levels on the residual stresses was investigated by x-ray diffraction. The composition of the passive films formed on each sample was assessed by x-ray photoelectron spectroscopy (XPS). The corrosion behavior was studied by electrochemical impedance spectroscopy and potentiodynamic polarization in phosphate-buffered solution at 37 °C. The semiconducting character of the passive films was determined by the Mott-Schottky approach. Our findings point to a positive effect of compressive loading on the corrosion resistance of the steel. The passive current density (ipass) decreased for the strained samples, especially for that subject to 15% compressive deformation for which ipass was 63% lower than for the as-received steel. The passive film formed at this condition presented strong Cr2O3 enrichment, according to XPS results. Moreover, the compressive stresses favored the formation of a passive film with fewer defects, decreasing the donors density. The results are discussed based on the correlation between residual stresses, passive film composition and its electronic properties.