Simulator for testing hardware and software of the office system with RFID tags

This paper presents the method for examining the properties of the RFID-tagged document management system. The system is composed of computers, where the software for supporting processes of the RFID-tagged documents was installed. Furthermore, the system cooperates with many other elements of the office (cabinets, sluices, copiers, try rider, end so one). The examination of the properties of the RFID-tagged document management system is, in this case, complex due to the number of a possible examination scenarios. The simulator method for examining the system properties was design and implemented. It allows to conduct the examination of the properties in a short period of time for numerous testing scenarios

Recent Studies of Corrosion - Fatigue Crack Growth on the 7081-T73511 Aluminium Alloy

This work aims to evaluate the effect of localized corrosion on the fatigue crack growth (FCG) resistance of the 7081-T73511 aluminium alloy. The understanding of this complex combined process was explained by the dissolution of adjacent 7081-T73511 aluminium matrix promoted by the Al7Cu2Fe second-phase particle and the crack tip interaction time with the aggressive medium. Fracture surfaces produced in air and in sea water fog at the testing conditions applied here, basically present the same appearance, with a transgranular, cleavage-like cracking mode for 8 <DK< 30 values

Hydrogen embrittlement evaluation of HSLA steels using small punch and slow strain rate tests

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Corrosion Fatigue of Aluminum-Copper-Lithium Alloy 2050-T84 Submitted at Salt Spray and Aqueous Saline Solution

Interest in the improvement of the structural performance of aircraft has begun in the substitution of aluminum alloys due to the possibility of reduction of density, an increase of stiffness, high fracture toughness, greater resistance to the propagation of cracks by fatigue and greater resistance to corrosion. In these issues, the aluminum-copper-lithium alloy 2050-T84 is outstanding, which presents excellent mechanical properties even when subjected to aggressive atmospheres. The failure of structural components of aircraft occurs due to several factors that may arise from microstructural defects and/or applied static or cyclic stresses associated with atypical environments such as cryogenic or corrosive. In this sense, the results have evidenced the presence of precipitates that influence in the increase of the mechanical strength, behavior of fracture toughness, fatigue life, and corrosion fatigue, in different temperatures and aggressive means. Tensile and fracture toughness tests at 23 and −60°C the material showed ductility retention without a significant difference in the results. Fatigue crack growth in air and corrosion fatigue with 3.5 and 5% NaCl and aqueous solution with 3.5% NaCl showed a meaning difference in the threshold region; however, for the Paris region at the saline environment, fatigue crack growth (FCG) rates are similar

The effect of hydrogen on the fracture toughness of friction-stir welded API 5L X70 pipeline steels

The hydrogen embrittlement (HE) leads to severe steel degradation of mechanical properties. The hydrogen atoms diffuse into the steel and get posi- tioned into reversible and irreversible trap sites. The pipe to transport oil and gas needs to be welded to construct long-distance pipeline projects; thus, friction-stir welding (FSW) has proven an excellent alternative to joining these pipelines. Therefore, this work assessed and analyzed the influence of hydro- gen on the microstructure and fracture toughness of API 5L X70 steel welded by friction-stir welding. The in-service conditions were simulated by charging the specimen electrolytically in a 3.5% NaCl water solution with an intensity current of 2 mA cm 2 . According to fracture toughness tests, the base metal (BM) was more affected by hydrogen embrittlement than the friction-stir zone (SZ), with a fracture toughness reduction of 20% after hydrogen charging. The SZ fracture toughness did not statistically show changes in hydrogen charging by the used times; however, the fracture mechanism changed from ductile to brittle-like after 4 days of charging. The SZ depicted a better fracture toughness than BM due to the bainitic microstructure, a significant amount of irrevers- ible hydrogen trapping.The authors acknowledge the National Council for Scientific and Technological Development scholarship, CNPq - Brazil, grant number: 165065/2017-6. This research used facilities of the Brazilian Nanotechnology National Laboratory (LNNano), part of the Brazilian Centre for Research in Energy and Materials (CNPEM), a private non-profit organization under the supervision of the Brazilian Ministry for Science, Technology, and Innovations (MCTI). In addition, the author would like to thank the staff at the University of S ̃ao Paulo, specifi- cally in the Materials Engineering Department at the S ̃ao Carlos School of Engineering (SMM, EESC-USP), the Laboratory for Friction and Wear Technology (LTAD) at F I G U R E 1 3 Orientation maps showing the crack path at the stable crack propagation region during the CTOD test. (A, B) H-free samples from the BM and SZ and (C, D) H-charged samples from BM and SZ [Colour figure can be viewed at wileyonlinelibrary.com] 12 GIAROLA ET AL . the Federal University of Uberlândia (UFU), and the Multi-user Laboratory Complex (C-LABMU) ate the State University of Ponta Grossa (UEPG). The authors also acknowledge Gabriel Severino de Almeida for the sample preparation. H.C. Pinto is a CNPq fellow. J. A. Avila is a Serra Hunter Fellow and a CNPq fellow.Peer ReviewedPostprint (published version

Austenite reversion kinetics and stability during tempering of an additively manufactured maraging 300 steel

Reverted austenite is a metastable phase that can be used in maraging steels to increase ductility via transformation-induced plasticity or TRIP effect. In the present study, 18Ni maraging steel samples were built by selective laser melting, homogenized at 820¿°C and then subjected to different isothermal tempering cycles aiming for martensite-to-austenite reversion. Thermodynamic simulations were used to estimate the inter-critical austenite¿+¿ferrite field and to interpret the results obtained after tempering. In-situ synchrotron X-ray diffraction was performed during the heating, soaking and cooling of the samples to characterize the martensite-to-austenite reversion kinetics and the reverted austenite stability upon cooling to room temperature. The reverted austenite size and distribution were measured by Electron Backscattered Diffraction. Results showed that the selected soaking temperatures of 610¿°C and 650¿°C promoted significant and gradual martensite-to-austenite reversion with high thermal stability. Tempering at 690¿°C caused massive and complete austenitization, resulting in low austenite stability upon cooling due to compositional homogenization.Peer ReviewedPostprint (author's final draft

Influence of phosphorus content and quenching/tempering temperatures on fracture toughness and fatigue life of SAE 5160 steel

This study investigates the influence of quenching/tempering temperatures on the fracture toughness and fatigue life of SAE 5160 steel, considering different phosphorus contents. Quenching and tempering treatments were applied to samples removed from different bars of commercial SAE 5160 steel with different P content. Three different austenitizing temperatures for quenching: 850, 900 and 1000 ºC and a constant holding time of 15 minutes were used. The oil temperature for quenching was kept at 66 ºC and the tempering conditions were 470, 500 and 530 ºC with the necessary time for a final hardness of 45 ± 3 HRC. Therefore, the heat treatments cycles were applied to specimens containing low (0.012 wt. (%)), medium (0.017 wt. (%)) and high (above 0.025 wt. (%)) phosphorus contents, in order to observe the effects of this element on the susceptibility of these steels to enhance quench and tempering embrittlements. The Charpy tests results showed that the phosphorus content analyzed in this work has caused embrittlement, even in the bars with the lowest P content, leading to intergranular fracture. However, if the nucleation life is taken into consideration, this embrittlement has no effect on the nucleation fatigue life of the component

Application of the small punch test to evaluate hydrogen embrittlement in steels and nickel alloys

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Corrosion behavior and microstructural characterization of friction stir welded API X70 steel

Friction stir welding (FSW) is an excellent alternative process used in pipelines circumferential welds due to fusion welded joint low corrosion resistance. This study describes the corrosion resistance as a function of the microstructural features resulting from an API X70 FSW welded joint. The microstructural features were examined by optical microscopy, scanning electron microscopy, and x-ray diffraction. The corrosion analysis was conducted employing potentiodynamic polarization tests using an electrochemical microcell, which allowed to test small circular areas delimited by a 2 mm in diameter O-ring gasket. The base metal and heat-affected zone were the most susceptible regions to corrosion due to their banded microstructures. The re-stirred-zone and stir zone were the most resistant regions to corrosion which was associated to grain refinement. The corrosion rate presented by the base metal and the heat-affected zone was approximately six times higher than the region of least susceptibility to corrosion, in this case, the re-stirred-zone.Peer ReviewedPostprint (author's final draft