Effect of dc on the Formability of Ti–6Al–4V

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Carl D. Ross ◽  
Thomas J. Kronenberger ◽  
John T. Roth
Keyword(s):  
Mechanical Properties ◽  
Mechanical Loading ◽  
Electrical Current ◽  
Dramatic Improvement ◽  
Bulk Deformation ◽  
Resistive Heating ◽  
Applied Current ◽  
Designed Experiments ◽  
Compressive Loads ◽  
Current Densities

Recent research has demonstrated that the mechanical properties of metals are altered when an electrical current is passed through the material. These studies suggest that titanium alloys, due to their low formability and need for dramatic improvement, should be subjected to additional study. The research presented herein further investigates the use of electricity to aid in the bulk deformation of Ti–6Al–4V under tensile and compressive loads. Extensive testing is presented, which documents the changes that occur in the formability of titanium due to the presence of an electrical current at varying current densities. Using carefully designed experiments, this study also characterizes and isolates the effect of resistive heating from the overall effect due to the electrical flow. This study clearly indicates that electrical flow affects the material beyond that which can be explained through resistive heating. The results demonstrate that an applied electrical current within the material during mechanical loading can greatly decrease the force needed to deform the titanium while also dramatically enhancing the degree to which it can be worked without fracturing. Isothermal testing further demonstrates that the changes are significantly beyond that which can be accounted for due to increases in the titanium’s temperature. The results are also supported by data from tests using pulsed and discontinuously applied current. Furthermore, current densities are identified that cause an enhanced formability behavior to occur. Overall, this work fully demonstrates that an electrical current can be used to significantly improve the formability of Ti–6Al–4V and that these improvements far exceed that which can be explained by resistive heating.

Effect of DC Current on the Formability of 6Al 4V Titanium

2006 ◽  
Author(s):  
Carl D. Ross ◽  
Thomas J. Kronenberger ◽  
John T. Roth
Keyword(s):  
Electrical Current ◽  
Dramatic Improvement ◽  
Metallic Materials ◽  
Resistive Heating ◽  
Applied Current ◽  
Superplastic Behavior ◽  
Compressive Loads ◽  
Current Densities ◽  
Dc Current ◽  
Electron Wind

Recent research has demonstrated that the mechanical properties of metallic materials are altered when an electrical current is passed through the material. These studies suggest that titanium, due to its low formability and potential for dramatic improvement, should be subjected to additional study. The research presented herein further investigates the use of electricity to aid in the bulk deformation of 6Al-4V titanium under tensile and compressive loads. Extensive testing is presented that documents the changes that occur in the formability of titanium due to the presence of an electron wind at varying current densities. Using carefully designed experiments, this study also characterizes and isolates the effect of resistive heating from the change due to the electrical flow alone. The results demonstrate that the presence of an electrical current within the material during deformation can greatly decrease the force needed to deform titanium while also dramatically enhancing the degree to which it can be worked without fracturing. Isothermal testing further demonstrates that the changes are significantly beyond that which can be accounted for due to increases in the titanium’s temperature. The results are also supported by data from tests using pulsed and discontinuously applied current. Furthermore, current densities are identified that cause an apparent superplastic behavior to occur. Overall, this work fully demonstrates that an electrical current can be used to significantly improve the formability of 6Al-4V titanium and that these improvements far exceed that which can be explained by resistive heating.

Coupled Multifield Finite Element Analysis Model of Upsetting Under an Applied Direct Current

2007 ◽  
Author(s):  
Thomas J. Kronenberger ◽  
David H. Johnson ◽  
John T. Roth
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Electron Flow ◽  
Theoretical Data ◽  
Electrical Current ◽  
Material Behavior ◽  
Deformation Model ◽  
Analysis Model ◽  
Resistive Heating ◽  
Element Analysis

Recent research studying the deformation of various metals in compression, while running an electric current through the material, has been quite promising. A problem occurs when trying to identify the specific mechanisms that cause the changes in the mechanical properties, however, since the flow of electricity produces resistive heating, which also affects the mechanical properties of metals. However, previous research has proven that not all of the effects on the properties can be explained through resistive heating, implying that the electron flow through the metal also causes changes to the mechanical properties. Therefore, this work develops a model capable of differentiating between the effects of resistive heating and the effects of the electron flow when deforming 6061-T6511 aluminum in compression. To accomplish this, a detailed finite element simulation has been developed using ANSYS® with two models in symbiosis. The first model predicts the temperature of the specimen and compression fixtures due to the applied electrical current. The resulting thermal data are then input into a deformation model to observe how the temperature change affects the deformation characteristics of the material. From this model, temperature profiles for the specimen are developed along with true stress vs. strain plots. This theoretical data is then compared to experimentally determined data collected for 6061-T6511 aluminum in compression. By knowing the exact effects of resistive heating, as obtained through the FEA model, the effects of the electron flow are isolated by subtracting out the effects of resistive heating from the data obtained experimentally. Future work will use these results to develop a new material behavior model that will incorporate both the resistive and flow effects from the electricity.

Micro Hardness in the Welded Area at Resistance Spot Welding

2016 ◽  
Vol 1138 ◽  
pp. 153-158
Author(s):  
Mihai Boca ◽  
Gheorghe Nagit ◽  
Laurenţiu Slătineanu
Keyword(s):  
Mechanical Properties ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Graphical Representation ◽  
Welding Process ◽  
Electrical Current ◽  
Micro Hardness ◽  
Current Time ◽  
Resistance Spot ◽  
Welding Spot

The resistance spot welding process represents the welding technology used to obtain assemblies trough welded spots characterized by adequate mechanical properties. This assembly process is used mainly into the automotive, petroleum and naval industries. It is applied due to the significant advantages concerning the technology and service properties of the obtained assembly. This paper purposes a study concerning the micro hardness change of an assembly made by resistance welding spot. The entire process of plastic deformations together with the solidification step developed in the presence of the heat generated during welding process determines the mechanical characteristics of the welded spot and, of course, of the assembly obtained. In such conditions, depending on the changes developed during the welding process, the micro hardness of the welded spot varies between the fusion area (FA) and heat affected zone (HAZ). In this way, the graphical representation of the micro hardness repartition gives clues about the weakness areas which don’t correspond to the requirements. As input factors, in this study, the values of current intensity, the electrical current time and the force pressure were considered. In order to solve the proposed problem and to graphically highlight the variation of the micro hardness obtained for welded points, it was used a classical welding device and a micro hardness device analyzer. The graphical representation shows that the micro-hardness and, as a consequence, some mechanical properties changes in the specified region and in the entire mass of the welded spot changes. In this way, the structure of welded spot is characterized by a variation of the hardness in the interest areas.

scholarly journals Electro-Absorbers: A Comparison on Their Performance with Jet-Absorbers and Absorption Columns

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 653
Author(s):  
Monserrat Castañeda-Juárez ◽  
Martín Muñoz-Morales ◽  
Fernanda Lourdes Souza ◽  
Cristina Sáez ◽  
Pablo Cañizares ◽  
...  
Keyword(s):  
Carbon Tetrachloride ◽  
Trichloroacetic Acid ◽  
Packed Column ◽  
Scale Up ◽  
Applied Current ◽  
Absorption Column ◽  
Applied Current Density ◽  
Current Densities ◽  
Surface Jet ◽  
By Products

This work focuses on the removal of perchloroethylene (PCE) from gaseous streams using absorbers connected with electrolyzers. Two types of absorption devices (jet absorber and absorption column) were compared. In addition, it has been evaluated the different by-products generated when a simultaneous electrolysis with diamond anodes is carried out. PCE was not mineralized, but it was transformed into phosgene that mainly derivates into carbon tetrachloride. Trichloroacetic acid was also formed, but in much lower amounts. Results showed a more efficient absorption of PCE in the packed column, which it is associated to the higher gas–liquid contact surface. Jet absorber seems to favor the production of carbon tetrachloride in gaseous phase, whereas the packed column promotes a higher concentration of trichloroacetic acid in liquid. It was also evaluated the scale up of the electrolytic stage of these electro-absorption devices by using a stack with five perforated electrode packages instead of a single cell. Clarification of the effect of the applied current density on the speciation attained after the electrolysis of the absorbent has been attempted. Experiments reveal similar results in terms of PCE removal and a reduced generation of gaseous intermediates at lower current densities.

Stability Analysis of Spin-Torque Nano-oscillator in the Rotating Frame

SPIN ◽  
2019 ◽  
Vol 09 (03) ◽  
pp. 1950008
Author(s):  
HaoHsuan Chen ◽  
Lang Zeng ◽  
ChingMing Lee ◽  
Weisheng Zhao
Keyword(s):  
High Performance ◽  
Electrical Current ◽  
Nonstationary Process ◽  
Laboratory Frame ◽  
Spin Torque ◽  
Rotating Frame ◽  
Magnetization Dynamics ◽  
Applied Current ◽  
Frequency Tunability ◽  
Out Of Plane

Spin-torque nano-oscillators (STNOs) have become one of the emerging and novel microwave devices with the high performance and tunability of GHz range frequency. The nanopillar structure with an out-of-plane (OP) spin polarizer and an in-plane (IP) magnetized free layer (FL) has been considered as a good candidate for the STNOs. Using the local rotational coordinate transformation, a nonstationary process describing magnetization dynamics in the laboratory frame is therefore transformed into a stationary one in the rotating frame. In this way, the state phase diagram of this type of STNOs is well established as a function of an applied current and external field, which is also evidenced by the macrospin simulations. Also, we show that the frequency tunability of the STNOs through electrical current can be well elevated by applying a static magnetic field anti-parallel to the spin-polarizer vector.

Polarization Studies of Aluminum Alloys In Water at 200 C and 300 C

CORROSION ◽  
1963 ◽  
Vol 19 (4) ◽  
pp. 146t-155t ◽  
Author(s):  
J. H. GREENBLATT ◽  
A. F. McMILLAN
Keyword(s):  
Anodic Polarization ◽  
Cathodic Polarization ◽  
Oxidation Potential ◽  
Electronic Conduction ◽  
Film Resistance ◽  
Applied Current ◽  
Weight Gain Data ◽  
Current Densities ◽  
Polarization Studies ◽  
Impressed Current

Abstract Specimens of commercial 2S aluminum and two special alloys containing iron and nickel were polarized anodically and cathodically at a number of different current densities at 200 C and 300 C. Weight gains were obtained and the potentials relative to the stainless steel autoclave were measured by an interrupter method. The weight gain data indicated that the polarizing current is being carried by electronic conduction. The potential-time curves for anodic polarization indicate differences between 2S aluminum and the alloys in that greater polarization is obtained with the latter. These curves also indicate that the impressed current decreases the film resistance. In all cases the potential reached a plateau value with time and this time was shorter for the alloys. The potential-time curves for cathodic polarization also show plateau values but the rise to a plateau value is in the opposite sense to the applied current. With increasing cathodic polarization the plateau values occur at more negative values of the potential. This latter trend is in the same direction as the applied polarizing current. This apparently is explained in terms of the build-up of the aluminum oxidation potential which acts in a sense opposite to the applied current. Again the time to reach plateau values was shorter for the alloys. Voltage current curves were also obtained on specimens left overnight (approximately 17 hours) at two different anodic polarizing currents. These curves indicated differences between 2S aluminum and the alloys; these differences are discussed in terms of the semi-conducting properties of the oxide film. The observations made on the differences in the properties of the oxide films on the materials examined as revealed by potential and polarization curves are discussed as to their significance in determining corrosion resistance.

Mechanical Properties of Oxides Formed by Anaerobic Corrosion of Steel

2000 ◽  
Vol 663 ◽  
Author(s):  
N.R. Smart ◽  
A.E. Bond ◽  
J.A.A. Crossley ◽  
P.C. Lovegrove ◽  
L. Werme
Keyword(s):  
Mechanical Properties ◽  
Mild Steel ◽  
Corrosion Product ◽  
Photoelectron Spectroscopy ◽  
Spent Nuclear Fuel ◽  
Control Cell ◽  
Geologic Repository ◽  
Compressive Loads ◽  
Anaerobic Corrosion ◽  
Corrosion Of Steel

ABSTRACTIn Sweden, it is proposed that spent nuclear fuel should be encapsulated in sealed cylindrical canisters for disposal in a geologic repository. The canisters would consist of a thick ferrous inner container and a copper overpack. If mechanical failure of the copper overpack occurred, allowing water to enter, there would be a build up of ferrous corrosion product, which could induce stresses in the outer copper canister. This paper describes an apparatus, the ‘stress cell’, which was designed to measure the expansion caused by the anaerobic corrosion of steel under compressive loads. The apparatus consisted of a stack of steel and copper discs, which were immersed in simulated anoxic groundwater. A system of levers amplified the change in height of the stack, and the displacement was measured using sensitive transducers. Three cells were set up; two contained alternate mild steel and copper discs, and the third, a control cell, consisted of alternate stainless steel and copper discs. A slight contraction of the control cell was observed but no expansion was measured in the mild steel - copper cells.In parallel, coupons of mild steel and cast iron were corroded in anoxic, artificial groundwater at 50°C and 80°C for several months. The coupons were examined by atomic force microscopy (AFM) to determine the mechanical properties and the structure of the corrosion product films, and X-ray photoelectron spectroscopy (XPS) to identify the chemical composition of the film.

Ultra-Fast NiSi2 Formation in p+-Si by High Current Densities

1998 ◽  
Vol 527 ◽  
Author(s):  
J.S. Huang ◽  
K.N. Tu
Keyword(s):  
Room Temperature ◽  
Line Length ◽  
Line Formation ◽  
High Current ◽  
Subsequent Growth ◽  
Applied Current ◽  
Electron Hole ◽  
Current Densities ◽  
Heavily Doped ◽  
Hole Recombination

ABSTRACTAn ultra-fast lateral formation of epitaxial NiSi2 line in heavily doped p+-Si diffused tub was created at room temperature ambient under the application of current densities of 106 A/cm2. A NiSi2 line of 140 μm long and I μm wide linking the cathode and anode contacts to p+-Si was formed within 1 second. Shorter lines were formed with lower current densities. The formation of shorter lines was again completed within 1 second and there was very little subsequent growth upon further stressing. The line length strongly depends upon applied current which tend to suggest that the line formation is limited by driving force rather than by kinetics. We propose that the ultra-fast silicide formation is a result of Ni interstitial diffusion in Si induced by electron-hole recombination heating and electromigration.

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