cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.6857756.v1
title: Estimation of local mechanical properties in friction stir welded AA6061-T6 by Small Punch Test (SPT)

description: ABSTRACT Friction Stir Welding (FSW) is a solid state process that has reach a strong technological impact in welding of aluminum alloys. Among its advantages, it may include the ability of joining materials that are difficult to weld by fusion. In welding of heat treatable aluminum alloys, some degradation in metallurgical properties is observed, so welds show lower strength than base metal. Welding parameters define the mechanical properties of the welded joints. Small Punch Tests (SPT) allow the analysis of local properties in weld zones because small specimens are required. In this paper, two batches of samples were prepared with different welding parameters and local mechanical properties were studied by SPT tests. An AA6061-T6 sheet with thickness 3 mm was selected as base metal. Thermal cycle, axial load and another welding parameters were fully recorded. From samples taken from welded coupons, weldments were characterized mechanically and metallurgically by conventional tests for comparison with SPT results. SPT is a valuable tool to estimate local mechanical properties in FSW welds.
DOI: 10.6084/m9.figshare.6857747
title: Influence of tempering time at 780°C on the creep resistance of ASTM A335 P91 steel

description: ABSTRACT It has been investigated the effect of tempering time at 780°C on the creep strength of ASTM A335 grade P91 steel. The tempering temperature corresponded to the industrial tempering temperature and the times evaluated were chosen in such a way to accumulate, between the tempering prior as received (40 min) and the treatment carried out in the laboratory, times of 3; 4; 5; 5,5; 5,7; 6 and 7 hours, so that in practice a double tempering was applied. Subsequently, the samples were creep tested at 600 ºC and 190 MPa up to rupture. The results show that a tempering time to 780 ºC has a very significant impact on the creep strength of the P91 steel. Up to 3 hours of tempering, the P91 steel retains its creep strength, with a minimum creep rate of 7x10-9 s-1. This creep strength falls off sharply to the 5 hours of tempering (1.5x10-7 s-1), and retrieved to the 5.5 hours (3 x10-8 s-1). This creep behavior is probably related to the evolution of the MX particles during tempering. The average size of the particles of the second phase in the samples tempered to 780 °C during different times and subjected to creep to 600 °C, would indirectly indicate a state of dissolution and reprecipitation of MX particles, which occurs during the tempering. Creep rupture occurs by the nucleation, growth and coalescence of cavities, in regions close to the prior austenite grain boundaries, resulting in a crack and propagation up to fracture.
DOI: 10.6084/m9.figshare.6857750
title: Orientation gradients in grain boundary proximity studied by EBSD

description: ABSTRACT The goal of this study is the evaluation of local misorientation, its distribution and orientation gradient in the microstructural development of a deep drawing quality steel sheet (AKDQ). The microstructure is characterized at sub-grain level spatial resolution using Electron Backscatter Diffraction (EBSD) in samples submitted to interrupted uniaxial tension in a notched sample and to typical solicitations in forming process through Nakajima tests with different sample geometries. The use of a notched sample allows performing a local study of the microstructural evolution in a set of identifiable grains as the material deforms, while the samples corresponding to Nakajima tests are used to study the behavior of the orientation gradient with the distance to the grain boundary under a statistical approach. From the latter analysis, two new EBSD-based parameters are introduced, named Gradient Average Severity (GAS) and Boundary Effective Thickness (BET). In 0.67 mm thick AKDQ steel sheets, the BET value as an indicator of GB influence zone is, in an average sense, independent on the grain size and the loading condition, below 3 μm. The gradient severity shows a good correlation with the mesoscopic plastic deformation. It is also observed that local misorientation accumulates in the grain boundary proximity, showing differences for each loading condition.
DOI: 10.6084/m9.figshare.6857753.v1
title: Design and analysis of different models of microfluidic devices evaluated in Enhanced Oil Recovery (EOR) assays

description: ABSTRACT Microfluidic devices are a new platform for Enhanced Oil Recovery (EOR) assays. The application of Colloidad Dispersion Gels (CDG) injection method has been proposed in recent years. However, the mechanism of oil recovery enhancement has not been completely elucidated. Its purpose is to mobilize oil by decreasing the permeability of channeled zones. The success of injection depends on the characteristics of water, the porous medium and the oil. Therefore, a successful injection in a reservoir can be different in another, hence the importance of a methodology for assessment prior to injection. This work applies micro and nanotechnology techniques to develop microfluidic chips used in EOR tests. EOR chips simulate the phenomena that occur in micro-nano scale reservoirs. Experiments analyzed multiphase flows in porous media inside chips. Generally, the first step of the experiments corresponds to fill the microchannels with water and then oil (1 poral volume 1PV). Second, water-injection takes place at constant flow rate until oil recovery ceases. Finally, either polymer or CDG is injected and their behavior is studied by digital image analysis. Results allowed obtaining graphs of oil residual saturation versus time for pore volumes of fluid used in EOR. The optimum configurations of the microchannels showed 80% of residual oil saturation after water injection.
DOI: 10.6084/m9.figshare.6857747.v1
title: Influence of tempering time at 780°C on the creep resistance of ASTM A335 P91 steel

description: ABSTRACT It has been investigated the effect of tempering time at 780°C on the creep strength of ASTM A335 grade P91 steel. The tempering temperature corresponded to the industrial tempering temperature and the times evaluated were chosen in such a way to accumulate, between the tempering prior as received (40 min) and the treatment carried out in the laboratory, times of 3; 4; 5; 5,5; 5,7; 6 and 7 hours, so that in practice a double tempering was applied. Subsequently, the samples were creep tested at 600 ºC and 190 MPa up to rupture. The results show that a tempering time to 780 ºC has a very significant impact on the creep strength of the P91 steel. Up to 3 hours of tempering, the P91 steel retains its creep strength, with a minimum creep rate of 7x10-9 s-1. This creep strength falls off sharply to the 5 hours of tempering (1.5x10-7 s-1), and retrieved to the 5.5 hours (3 x10-8 s-1). This creep behavior is probably related to the evolution of the MX particles during tempering. The average size of the particles of the second phase in the samples tempered to 780 °C during different times and subjected to creep to 600 °C, would indirectly indicate a state of dissolution and reprecipitation of MX particles, which occurs during the tempering. Creep rupture occurs by the nucleation, growth and coalescence of cavities, in regions close to the prior austenite grain boundaries, resulting in a crack and propagation up to fracture.
DOI: 10.6084/m9.figshare.6857750.v1
title: Orientation gradients in grain boundary proximity studied by EBSD

description: ABSTRACT The goal of this study is the evaluation of local misorientation, its distribution and orientation gradient in the microstructural development of a deep drawing quality steel sheet (AKDQ). The microstructure is characterized at sub-grain level spatial resolution using Electron Backscatter Diffraction (EBSD) in samples submitted to interrupted uniaxial tension in a notched sample and to typical solicitations in forming process through Nakajima tests with different sample geometries. The use of a notched sample allows performing a local study of the microstructural evolution in a set of identifiable grains as the material deforms, while the samples corresponding to Nakajima tests are used to study the behavior of the orientation gradient with the distance to the grain boundary under a statistical approach. From the latter analysis, two new EBSD-based parameters are introduced, named Gradient Average Severity (GAS) and Boundary Effective Thickness (BET). In 0.67 mm thick AKDQ steel sheets, the BET value as an indicator of GB influence zone is, in an average sense, independent on the grain size and the loading condition, below 3 μm. The gradient severity shows a good correlation with the mesoscopic plastic deformation. It is also observed that local misorientation accumulates in the grain boundary proximity, showing differences for each loading condition.
DOI: 10.6084/m9.figshare.6857741
title: Wind Power in Girau do Ponciano, Alagoas, Brazil Using Anemometric Data and Microscale Modeling

description: Abstract The wind potential in the Agreste region of Northeastern Brazil has important features for energy exploration, but, stills unexplored. This work analyzes 3.1 yrs anemometer tower measurements in the Girau do Ponciano, Alagoas state. The observational data was recorded from October 2007 to October 2010. Three periods were defined to constrain the seasonal wind patterns: Annual, Dry (October-January) and Wet (May-August). Hourly and monthly series showed the average wind speed was higher than 7 m s-1, reaching 8.5 m s-1 during the dry season. Further, the wind direction was also favorable with less variability, concentrated between NE and SE. During nighttime the wind speed ≥ 10 m s-1 were more frequent. The Weibull fit is more distributed (concentrated) during the dry (wet) season close to 8 m s-1 (7 m s-1). The AEP (Cf) parameter estimated by the WAsP model varied between 3 to 10 GWh (35% to 65%). Nevertheless, Girau do Ponciano domain was positioned nearby two highways and close to an electrical substation in the Arapiraca city. Other geographic conditions (topography inclination &lt; 15°, the absence of obstacles, and low vegetation) are also favorable to future wind farm installation in this area.
DOI: 10.6084/m9.figshare.6857744
title: Computational simulation of an Erichsen test applied on a DC-06 steel sheet

description: ABSTRACT Nowadays, the use of computer simulation on forming processes as stamping and its variants, is an habitual development activity of big industries, and also it is slowly being introduced in SME (Small and Mediumsize Enterprise). One of the main advantages of it is application lies-in the reduction of costs regarding new projects, products and processes developments. Likewise, these tools are widely used to reproduce complex physical phenomena. During the deep drawing process, the material is mechanically stressed, therefore requires knowledge of it is properties, such as ductility, mechanical strength and plasticity. Thus, characterization tests like the Erichsen test are performed to recreate a controlled deep drawing process. In this paper, using the Simufact.Forming software, a deep drawing test was simulated, for a steel sheet DC06 IF-base, of nominal thickness 0.7mm. During the simulation is taken into account the conditions of lubrication, pressure of blank holder, dimensions of the dies and friction coefficient. At the same time, the experimental test was also performed in order to compare and validate the simulated results.
DOI: 10.6084/m9.figshare.6857744.v1
title: Computational simulation of an Erichsen test applied on a DC-06 steel sheet

description: ABSTRACT Nowadays, the use of computer simulation on forming processes as stamping and its variants, is an habitual development activity of big industries, and also it is slowly being introduced in SME (Small and Mediumsize Enterprise). One of the main advantages of it is application lies-in the reduction of costs regarding new projects, products and processes developments. Likewise, these tools are widely used to reproduce complex physical phenomena. During the deep drawing process, the material is mechanically stressed, therefore requires knowledge of it is properties, such as ductility, mechanical strength and plasticity. Thus, characterization tests like the Erichsen test are performed to recreate a controlled deep drawing process. In this paper, using the Simufact.Forming software, a deep drawing test was simulated, for a steel sheet DC06 IF-base, of nominal thickness 0.7mm. During the simulation is taken into account the conditions of lubrication, pressure of blank holder, dimensions of the dies and friction coefficient. At the same time, the experimental test was also performed in order to compare and validate the simulated results.
DOI: 10.6084/m9.figshare.6857738
title: Archaeometallurgical studies about objects of Falda del Cerro site (Catamarca, Argentina)

description: ABSTRACT Falda del Cerro is an archaeological site located on the western slope of the Aconquija Mountains (Catamarca, Argentina) [1]. Its human occupation is radiocarbonically dated to the first centuries AD [2]. The site presents circular and semi-circular enclosures constructed with stone walls which foundations are dug into the bedrock. Associated pottery belongs to the period’s distinctive styles: Alpatauca, Gris Pulido, Ante Pulido, Condorhuasi, etc. Surface assemblage and excavated contexts in the area evinced pottery fragments with vitrification evidence on them, mineral remains (probably used as raw material), slag and metal objects [3]. Such evidence led us to suppose that activities related to metallurgic production took place in Falda del Cerro. The present paper is focused on six metal objects found in the site. Our aim is to characterize these objects in order to determine chemical similarities or differences between them. Energy-dispersive X-ray spectroscopy (EDAX) analyses were made in order to chemically characterize the sample. The obtained data will allow us to identify the existence of metallic production in the studied area. This preliminary study initiates the research about chaîne opératoire of metallurgical production on the southern Calchaquí valleys during the first millennium A.D. Future investigations will aim to produce the analysis of mineral remains found in the site and to explore the potential sources of raw material.
DOI: 10.6084/m9.figshare.6857741.v1
title: Wind Power in Girau do Ponciano, Alagoas, Brazil Using Anemometric Data and Microscale Modeling

description: Abstract The wind potential in the Agreste region of Northeastern Brazil has important features for energy exploration, but, stills unexplored. This work analyzes 3.1 yrs anemometer tower measurements in the Girau do Ponciano, Alagoas state. The observational data was recorded from October 2007 to October 2010. Three periods were defined to constrain the seasonal wind patterns: Annual, Dry (October-January) and Wet (May-August). Hourly and monthly series showed the average wind speed was higher than 7 m s-1, reaching 8.5 m s-1 during the dry season. Further, the wind direction was also favorable with less variability, concentrated between NE and SE. During nighttime the wind speed ≥ 10 m s-1 were more frequent. The Weibull fit is more distributed (concentrated) during the dry (wet) season close to 8 m s-1 (7 m s-1). The AEP (Cf) parameter estimated by the WAsP model varied between 3 to 10 GWh (35% to 65%). Nevertheless, Girau do Ponciano domain was positioned nearby two highways and close to an electrical substation in the Arapiraca city. Other geographic conditions (topography inclination &lt; 15°, the absence of obstacles, and low vegetation) are also favorable to future wind farm installation in this area.
DOI: 10.6084/m9.figshare.6857738.v1
title: Archaeometallurgical studies about objects of Falda del Cerro site (Catamarca, Argentina)

description: ABSTRACT Falda del Cerro is an archaeological site located on the western slope of the Aconquija Mountains (Catamarca, Argentina) [1]. Its human occupation is radiocarbonically dated to the first centuries AD [2]. The site presents circular and semi-circular enclosures constructed with stone walls which foundations are dug into the bedrock. Associated pottery belongs to the period’s distinctive styles: Alpatauca, Gris Pulido, Ante Pulido, Condorhuasi, etc. Surface assemblage and excavated contexts in the area evinced pottery fragments with vitrification evidence on them, mineral remains (probably used as raw material), slag and metal objects [3]. Such evidence led us to suppose that activities related to metallurgic production took place in Falda del Cerro. The present paper is focused on six metal objects found in the site. Our aim is to characterize these objects in order to determine chemical similarities or differences between them. Energy-dispersive X-ray spectroscopy (EDAX) analyses were made in order to chemically characterize the sample. The obtained data will allow us to identify the existence of metallic production in the studied area. This preliminary study initiates the research about chaîne opératoire of metallurgical production on the southern Calchaquí valleys during the first millennium A.D. Future investigations will aim to produce the analysis of mineral remains found in the site and to explore the potential sources of raw material.
DOI: 10.6084/m9.figshare.6857732
title: Estimation of mechanical properties of metallic materials using inverse method in SPT

description: ABSTRACT Mechanical characterization of metallic materials by Small Punch Test (SPT) allows to evaluate uniaxial tensile properties [1]. In this work, by means of an inverse procedure and numerical simulation of SPT tests we estimate uniaxial tensile properties of AISI 304L stainless steel. We detail the applied procedure to estimate the yield stress where the two parameter Hollomon relation is assumed as a constitutive relationship. According to the obtained results, it can be suggested that the developed procedure is suitable for estimating properties in metallic materials, if a suitable constitutive equation is used.
DOI: 10.6084/m9.figshare.6857735
title: Influence of thermal treatments in nanotubular anodic coatings of TiO2

description: ABSTRACT TiO2 is a semiconductor widely used in heterogeneous photocatalysis processes for water decontamination. Several studies indicate that ordered nanostructures in anatase phase improve the photocatalytic properties with respect to other morphologies and crystal structures of TiO2. The aim of the present work is to evaluate the influence of different thermal treatments on the structural integrity and crystal structure of the nanotubular TiO2 coatings synthesized by the anodic oxidation technique. A solution of 0.6% w/w ammonium fluoride and 3.5% w/w water in ethylene glycol was used as the electrolyte for the oxidation. A direct current was used at a constant voltage of 45 V during 2 h. After the anodic oxidation, thermal treatments of 2 h and 4 h at 450, 550 and 650 °C with a heating ramp of 10 ºC/min were performed. Morphology and crystalline structure of the coatings were characterized by scanning electron microscopy and X-ray diffraction, respectively. TiO2 coatings of nanotubes about 85 nm inner diameter, 18 nm wall thick and 7 ?m in length (mean value) were obtained. The nanotubes maintained their structural integrity without changes in the dimensions with the applied thermal treatments. However, the morphology of the walls of the nanotubes was modified with the time and temperature of the thermal treatments, evidencing the formation of anatase crystals. Even on the coatings thermally treated at 550 °C, nanocrystalline anatase deposits on the outside wall of the nanotubes were observed. Regarding the crystal structure, the coatings were amorphous previously to the thermal treatments and were crystalline in anatase phase after thereof, indicating the anatase stabilization even up to 650 °C, temperature at which the rutile phase appeared.
DOI: 10.6084/m9.figshare.6857729
title: The successful safety and health experience in the London 2012 Olympic Park construction: an interview with Alistair Gibb

description: Abstract Alistair Gibb, a civil engineer, has been a professor at Loughborough University, United Kingdom, since 1993. He is a researcher in safety & health and in construction innovation technology. He is a member of the European Construction Institute, and of the Institution of Civil Engineers. Before he became a professor, he worked as a manager in the construction industry, which provided him with a useful interface by linking academia and industry experiences. Dr. Gibb lead researches about the successful safety & health performance during the London 2012 Olympic Park construction, as there were no fatal accidents and it was delivered on time and within the budget. In November 2015, to better understand this experience and to contribute for the prevention of work accidents in large construction sites, Brazilian researchers from the FAPESP Thematic Project (Process No. 2012/04721-1) invited Professor Gibb to participate in the 50th Forum AT (occupational accidents’ forum), about safety & health in large construction sites. This interview was granted at that opportunity.
DOI: 10.6084/m9.figshare.6857735.v1
title: Influence of thermal treatments in nanotubular anodic coatings of TiO2

description: ABSTRACT TiO2 is a semiconductor widely used in heterogeneous photocatalysis processes for water decontamination. Several studies indicate that ordered nanostructures in anatase phase improve the photocatalytic properties with respect to other morphologies and crystal structures of TiO2. The aim of the present work is to evaluate the influence of different thermal treatments on the structural integrity and crystal structure of the nanotubular TiO2 coatings synthesized by the anodic oxidation technique. A solution of 0.6% w/w ammonium fluoride and 3.5% w/w water in ethylene glycol was used as the electrolyte for the oxidation. A direct current was used at a constant voltage of 45 V during 2 h. After the anodic oxidation, thermal treatments of 2 h and 4 h at 450, 550 and 650 °C with a heating ramp of 10 ºC/min were performed. Morphology and crystalline structure of the coatings were characterized by scanning electron microscopy and X-ray diffraction, respectively. TiO2 coatings of nanotubes about 85 nm inner diameter, 18 nm wall thick and 7 ?m in length (mean value) were obtained. The nanotubes maintained their structural integrity without changes in the dimensions with the applied thermal treatments. However, the morphology of the walls of the nanotubes was modified with the time and temperature of the thermal treatments, evidencing the formation of anatase crystals. Even on the coatings thermally treated at 550 °C, nanocrystalline anatase deposits on the outside wall of the nanotubes were observed. Regarding the crystal structure, the coatings were amorphous previously to the thermal treatments and were crystalline in anatase phase after thereof, indicating the anatase stabilization even up to 650 °C, temperature at which the rutile phase appeared.