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REBELLO, J. M. A. ; BURROWES, M. ; PEREIRA, GABRIELA R. ; TAVARES, L. M. (2014).
Resumo: Computational simulations and reliability analysis were used to optimize an automated ultrasonic system used in pipe inspections in a manufacture plant in operation. Through the application of these tools the quality of the final product could be improved from more efficiency inspections. The main purpose was to establish the influence of each variable involved in the capacity of the ultrasonic system in detecting flaws. Tests were conducted considering a calibration API X65 steel pipe in which fitted reflectors were inserted artificially according to the DNV-OS-F101 standard. Experimental variables such as index, probe angle and gate position showed an important effect on the efficiency of the system and statistical analyses proved to be a powerful tool to validate the simulated and experimental results.
CHEHUAN, THIAGO ; DREILICH, VANESSA ; de Assis, Kioshy S. ; de Sousa, Flávio V.V. ; Mattos, Oscar R. (2014).
Resumo: This work focuses the effect of secondary austenite (γ2) on corrosion resistance of welded joints. The welded joints were obtained by pulsed gas metal arc welding (GMAW-P) with three different heat inputs. Each joint and their respective sub-regions through thickness were characterised by optical microscopy and scanning electron microscopy. The results were correlated with double loop electrochemical potentiodynamic reactivation (DL-EPR) and sulphide stress corrosion tests. The results suggest a good agreement between the DL-EPR and the four point bending tests. It was also verified that the simple presence of γ2 does not necessarily gives rise to loss of corrosion resistance.
Muri, P. ; Sousa, F.V.V ; DE ASSIS, KIOSHY S. ; ROCHA, A.C. ; MATTOS, OSCAR R. ; MARGARIT-MATTOS, ISABEL C.P. (2014).
Resumo:
MURI, P. ; SOUSA, F.V.V. ; ASSIS, K.S. ; ROCHA, A.C. ; Mattos, O.R. ; Margarit-Mattos, I.C.P. (2014).
Resumo: This paper is dedicated to the establishment of experimental conditions for practical use of Double Loop Electrochemical Potentiodynamic Reactivation method (DL-EPR) to characterize the degree of sensitization in AISI 304 austenitic stainless steel based in the standard ISO 12732. The steel undergoes heat treatments to solubilize the commercial material and later controlling its sensitization degree. Microstructure of the samples with quantification of the sensitization was obtained according to ASTM E1245. The standards ASTM A262 and ASTM G48 were used, respectively, to rank the sensitization and the susceptibility to pitting corrosion of the different samples. Solutions of sulfuric acid 0.5 mol.dm−3 with three contents of KSCN (0.001, 0.01, 0.05 mol.dm−3) and three different potential scan rates (0.56, 1.67 and 4.2 mV.s−1) were used for DL-EPR measurements. Results illustrate the high dependence of Ir/Ia on KSCN concentration and scan rate, even respecting the standard limits. Therefore, table presented by ISO 12732 addressing Ir/Ia to sensitization degree can be misleading as it is not linked with specific experimental conditions. On the other hand, DL-EPR can be direct related to sensitization when reference materials are used. For that, heat treated steel must be used to obtain DL-EPR curves considering electrolyte composition and potential scan rate. These results are the base to establish a reference curve of Ir/Ia versus the sensitization degree. This curve can be used later to detect sensitization of the same kind of steel in-service with Ir/Ia values measured in-situ. The diagnosis of susceptibility to localized corrosion obtained by various standard procedures is critically evaluated.
Leitão, R.G. ; PALUMBO, A. ; Souza, P.A.V.R. ; PEREIRA, G. R. ; CANELLAS, C.G.L. ; ANJOS, M.J. ; Nasciutti, L.E. ; LOPES, R. T. (2014).
Resumo: Prostate cancer (PCa) currently represents the second most prevalent malignant neoplasia in men, representing 21% of all cancer cases. Benign Prostate Hyperplasia (BPH) is an illness prevailing in men above the age of 50, close to 90% after the age of 80. The prostate presents a high zinc concentration, about 10-fold higher than any other body tissue. In this work, samples of human prostate tissues with cancer, BPH and normal tissue were analyzed utilizing total reflection X-ray fluorescence spectroscopy using synchrotron radiation technique (SR-TXRF) to investigate the differences in the elemental concentrations in these tissues. SR-TXRF analyses were performed at the X-ray fluorescence beamline at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo. It was possible to determine the concentrations of the following elements: P, S, K, Ca, Fe, Cu, Zn and Rb. By using Mann–Whitney U test it was observed that almost all elements presented concentrations with significant differences (α=0.05) between the groups studied.
