Navegando por Autor "Sousa, Gustavo Henrique"

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Corrosion behavior of low carbon steel processed by ECAP in neutral and alkaline environment.
(2021) Braga, Jorgimara de Oliveira; Lins, Jefferson Fabricio; Castro, Gabriel Pessoa de; Almeida Junior, Helder Alves de; Santos, Igor Cuzzuol dos; Sousa, Gustavo Henrique; Criscuolo, Izabel Lima; Santana, Cláudio Márcio; Pereira, Ursula Cid
The purpose of this study was to evaluate the corrosion behavior of 1010 steel processed by Equal Channel Angular Pressing (ECAP), a technique that induces severe plastic deformation (SPD) in materials. The samples were processed by one and two passes of ECAP throught routes A and C. The corrosion behavior was evaluate using the potentiodynamic polarization and electrochemical impedance spectroscopy, using NaCl (pH= 6.5) and sodium hydroxide/sodium phosphate (pH= 10.5) solutions. The polarization tests showed better performance for the samples processed by ECAP than in the as cast samples both in alkaline and neutral solutions. The results showed that alkaline solution presented higher corrosion rate for the as cast and one ECAP pass materials. It is seen that samples processed throught routes A and C develop a film stabilization on the surface of these samples. In addition, the values of polarization resistance obtained from the electrochemical impedance spectroscopy in NaCl environment were higher for sample processed in route C.
Thermodynamic simulations and industrial trials applied to inclusion control of SAE 9254 Si-Mn killed steel.
(2020) Lima, Ermani Vinicius de Oliveira; Sousa, Gustavo Henrique; Costa Neto, Joaquim Gonçalves; Peixoto, Johne Jesus Mol; Silva, Carlos Antônio da
Applying SAE 9254 steel to springs manufacture requires precise control of non-metallic inclusions. The effects of operational parameters on steel cleanliness such as the amount of BOF slag carry over as well as addition of graphite and ladle Furnace slag basicity have been evaluated using Chemical EQuilibrium Calculations for the Steel Industry (CEQCSI) software. Slag basicity is expected to strongly influence steel inclusions. Accordingly, industrial tests were carried out for characterization of inclusions in steel samples, collected at the beginning, middle, and end steps of Ladle Furnace refining treatment and in billet and wire rod products. Inclusion features such as quantity, size distribution, and chemical composition were assessed by SEM (Scanning Electron Microscopy) using EDS (Dispersive Energy Spectroscopy) and ASCAT (Automated Steel Cleanliness Analysis Tool). The results showed a decrease in the amount of inclusions by up to 60 pct and an increase from 72 to 98 pct of inclusions of less than 10 lm in the wire rod due to the increased basicity. Also under increased slag basicity, the inclusions composition remained in the low-temperature liquidus region, an important characteristic related to the best deformability of the inclusions. The amount and average size of the major sulfides S-Mn and S-Mn-Cr in the wire rod decreases with decreasing sulfur content in the steel.