A Review of Electrically-Assisted Manufacturing With Emphasis on Modeling and Understanding of the Electroplastic Effect

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Brandt J. Ruszkiewicz ◽  
Tyler Grimm ◽  
Ihab Ragai ◽  
Laine Mears ◽  
John T. Roth
Keyword(s):  
Fuel Economy ◽  
Elastic Recovery ◽  
Fuel Efficiency ◽  
High Strength ◽  
Carbon Steels ◽  
Metallic Materials ◽  
Low Carbon ◽  
Electroplastic Effect ◽  
Electrically Assisted ◽  
Electrically Assisted Manufacturing

Increasingly strict fuel efficiency standards have driven the aerospace and automotive industries to improve the fuel economy of their fleets. A key method for feasibly improving the fuel economy is by decreasing the weight, which requires the introduction of materials with high strength to weight ratios into airplane and vehicle designs. Many of these materials are not as formable or machinable as conventional low carbon steels, making production difficult when using traditional forming and machining strategies and capital. Electrical augmentation offers a potential solution to this dilemma through enhancing process capabilities and allowing for continued use of existing equipment. The use of electricity to aid in deformation of metallic materials is termed as electrically assisted manufacturing (EAM). The direct effect of electricity on the deformation of metallic materials is termed as electroplastic effect. This paper presents a summary of the current state-of-the-art in using electric current to augment existing manufacturing processes for processing of higher-strength materials. Advantages of this process include flow stress and forming force reduction, increased formability, decreased elastic recovery, fracture mode transformation from brittle to ductile, decreased overall process energy, and decreased cutting forces in machining. There is currently a lack of agreement as to the underlying mechanisms of the electroplastic effect. Therefore, this paper presents the four main existing theories and the experimental understanding of these theories, along with modeling approaches for understanding and predicting the electroplastic effect.

Thermal Response Modeling of Sheet Metals in Uniaxial Tension During Electrically-Assisted Forming

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Joshua J. Jones ◽  
Laine Mears
Keyword(s):  
Fuel Efficiency ◽  
Thermal Response ◽  
High Strength ◽  
Electrical Current ◽  
Applied Current ◽  
Electroplastic Effect ◽  
Electrically Assisted ◽  
Response Modeling ◽  
Deformation Tests ◽  
Good Agreement

For the current practice of improving fuel efficiency and reducing emissions in the automotive sector, it is becoming more common to use low density/high strength materials instead of costly engine/drivetrain technologies. With these materials there are normally many manufacturing difficulties that arise during their incorporation to the vehicle. As a result, new processes which improve the manufacturability of these materials are necessary. This work examines the manufacturing technique of electrically-assisted forming (EAF) where an electrical current is applied to the workpiece during deformation to modify the material's formability. In this work, the thermal response of sheet metal for stationary (i.e., no deformation) and deformation tests using this process are explored and modeled. The results of the model show good agreement for the stationary tests while for the deformation tests, the model predicts that all of the applied electrical current does not generate Joule heating. Thus, this work suggests from the observed response that a portion of the applied current may be directly aiding in deformation (i.e., the electroplastic effect). Additionally, the stress/strain response of Mg AZ31 under tensile forming using EAF is presented and compared to prior experimental work for this material.

MITTAL DI-FORM T700, HF80Y100T

Alloy Digest ◽  
2007 ◽  
Vol 56 (2) ◽  
Keyword(s):  
Automotive Industry ◽  
High Strength ◽  
Martensite Phase ◽  
Carbon Steels ◽  
Ferrite Phase ◽  
Dual Phase ◽  
Low Carbon ◽  
Advanced High Strength Steel ◽  
Dp Steels ◽  
Soft Ferrite

Abstract MITTAL DI-FORM T700 and HF80Y100T are low-carbon steels with a manganese and silicon composition. Dual-phase (DP) steels are one of the important advanced high-strength steel (AHSS) products developed for the automotive industry. Their microstructure typically consists of a soft ferrite phase with dispersed islands of a hard martensite phase. The martensite phase is substantially stronger than the ferrite phase. The DI-FORM grades exhibit low yield-to-tensile strengths, and the numeric designation in the name corresponds to the tensile strength. This datasheet provides information on microstructure and tensile properties as well as deformation and fatigue. It also includes information on forming. Filing Code: SA-561. Producer or source: Mittal Steel USA Flat Products.

Enhancement of the tensile shear strength for joining low-ductility aluminium to high-strength steel by using electrically-assisted mechanical clinching (EAMC)

2021 ◽  
pp. 095440542199565
Author(s):  
Abozar Barimani-Varandi ◽  
Abdolhossein Jalali Aghchai
Keyword(s):  
Shear Strength ◽  
High Strength Steel ◽  
High Strength ◽  
Fe Model ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Electroplastic Effect ◽  
Fracture Displacement ◽  
Electrically Assisted ◽  
Mechanical Clinching

The present work studied the enhancement of the tensile shear strength for joining AA6061-T6 aluminium to galvanized DP590 steel via electrically-assisted mechanical clinching (EAMC) using an integrated 2D FE model. To defeat the difficulties of joining low-ductility aluminium alloy to high-strength steel, the electroplastic effect obtained from the electrically-assisted process was applied to enhance the clinch-ability. For this purpose, the results of experiments performed by the chamfering punches with and without electrically-assisted pre-heating were compared. Joint cross-section, failure load, failure mode, fracture displacement, material flow, and failure mechanism were assessed in order to study the failure behaviour. The results showed that the joints clinched at the EAMC condition failed with the dominant dimpled mechanism observed on the fracture surface of AA6061 side, achieved from the athermal effect of the electroplasticity. Besides, these joints were strengthened 32% with a much more fracture displacement around 20% compared with non-electrically-assisted pre-heating.

A New Approach Using EBSD to Quantitatively Distinguish Complex Transformation Products Along the HAZ in X80 Linepipe Steel

2014 ◽  
Author(s):  
Jennifer M. Reichert ◽  
Matthias Militzer ◽  
Warren J. Poole ◽  
Laurie Collins
Keyword(s):  
Orientation Relationship ◽  
Transformation Temperature ◽  
Retained Austenite ◽  
Electron Backscatter Diffraction ◽  
High Strength ◽  
Transformation Products ◽  
Carbon Steels ◽  
Low Carbon ◽  
Structure Property ◽  
Linepipe Steel

State-of-the-art linepipe steels are microalloyed low-carbon steels that combine high strength and fracture toughness with good weldability. During welding of pipe sections the heat affected zone (HAZ) experiences rapid thermal cycles resulting in a graded microstructure that can be significantly different from that of the base metal. In particular a variety of bainitic microstructures can form in the HAZ. Depending on the type of bainite mechanical properties may be improved or may lead to poor fracture resistance and be detrimental to the overall HAZ performance. Optical microscopy is not sufficient to differentiate bainitic morphologies which vary with the transformation temperature. The investigated X80 linepipe steel also contains retained austenite at room temperature. Based on the retained austenite it is possible to characterize the orientation relationship (OR) between austenite and the transformation products. It is found that bainite shows an orientation relationship near Kurdjumov-Sachs with the prior austenite. Variant selection is related to the driving force for the bainite reaction and hence depends on the transformation temperature. In the current study Electron BackScatter Diffraction (EBSD) mapping is used to characterize transformation products based on their orientation relationship. This approach offers a quantitative way to determine volume fractions of different types of bainite in complex HAZ microstructures which is necessary to establish structure-property relationships of the HAZ.

Development of Low Carbon Microalloyed Bainitic Steels for Structural Plate Applications

2005 ◽  
Vol 500-501 ◽  
pp. 573-580 ◽  
Author(s):  
D. Ormston ◽  
Volker Schwinn ◽  
Klaus Hulka
Keyword(s):  
High Strength ◽  
Carbon Steels ◽  
Chemical Compositions ◽  
Low Carbon ◽  
Controlled Processes ◽  
Bainitic Steels ◽  
Steel Grades ◽  
Carbon Microalloyed ◽  
Hot Rolled ◽  
Plate Steels

Steels with bainitic microstructures show the capacity to fulfil the requirements of high strength and low temperature toughness necessary for plate steels in specialised industrial constructions. The introduction of steels with higher strength allows for weight reductions of steel constructions. This paper investigates the development of hot rolled structural plate steels through laboratory hot rolling simulations of thermo-mechanically controlled processes (TMCP). Specific alloying and microalloying along with an optimised TMCP process has allowed high tensile properties to be achieved in combination with high levels of toughness. Tensile strengths of up to 900 MPa have been achieved with Charpy V-notch toughness greater than 200J at –40°C. Elements such as molybdenum, niobium and boron have been added to low carbon steels to promote the formation of fully bainitic microstructures with much lightened chemical compositions. The presented concepts allow the production of steel grades above S500 up to S690.

Refinement of Cementite in High Strength Steel Plates by Rapid Heating and Tempering

2007 ◽  
Vol 539-543 ◽  
pp. 4720-4725 ◽  
Author(s):  
A. Nagao ◽  
K. Hayashi ◽  
K. Oi ◽  
S. Mitao ◽  
N. Shikanai
Keyword(s):  
Rapid Heating ◽  
High Strength ◽  
Average Diameter ◽  
Carbon Steels ◽  
Steel Plates ◽  
Heating Process ◽  
Low Carbon ◽  
Precipitation Behavior ◽  
Heating Rates ◽  
Extraction Replica

The precipitation behavior of cementite in low carbon steels at various heating rates from 0.3 to 100 K/s has been studied using a high-frequency induction heating apparatus. The materials used in this study were steel platesfor welded structures: 610 and 780 MPa class steel plates with a mixed microstructure of bainite and martensite.Cementite was observed using a carbon extraction replica method and the hardness and toughness were also examined. When heated at the conventional slow rate of 0.3 K/s, relatively large cementite particles with an average diameter of 72 nm precipitated at the lath boundaries, whereas when heated at a rapid rate over 3.0 K/s, cementite precipitated both within the laths and at the lath boundaries, and the cementite was refined down to an average diameter of 54 nm. With such refinement of the cementite, the toughness was improved. On the other hand, the hardness was irrespective of the heating rate and was dependent on the tempering parameter. TEM observations of the cementite precipitation behavior during the rapid heating process revealed that cementite begins to precipitate at the lath boundaries at about 773 K and within the laths at about 873 K. It is concluded that rapid heating especially from 773 to 873 K contributes to the cementite refinement and consequently the improvement in toughness. The effect of alloying elements such as chromium, molybdenum or silicon on the cementite growth during the rapid heating and tempering treatment is also discussed.

The Microstructural Effects on Magnesium Alloy AZ31B-O While Undergoing an Electrically-Assisted Manufacturing Process

2009 ◽  
Author(s):  
Timothy A. McNeal ◽  
Jeffrey A. Beers ◽  
John T. Roth
Keyword(s):  
Deformation Process ◽  
Microstructural Analysis ◽  
High Strength ◽  
Strength Properties ◽  
High Demand ◽  
Electrically Assisted ◽  
Magnesium Alloy Az31b ◽  
Microstructural Effects ◽  
Lightweight Alloys ◽  
Electrically Assisted Manufacturing

In today’s industry, the need for lightweight alloys with high strength properties is growing. More specifically, magnesium alloys are in high demand. Unfortunately, magnesium’s limited formability hinders its broad range applicability. Previous research has discovered that the tensile formability of this alloy can be increased using electrical pulsing during the deformation process, referred to as Electrically-Assisted Manufacturing (EAM). Although this method increases a material’s formability (i.e. lowers flow stress, increases elongation, and reduces springback), a detailed analysis is required to further evaluate the effects of electricity on the material’s microstructure. The research herein will examine the microstructure of Magnesium AZ31B-O specimens that were deformed under uniaxial tension while electrically pulsed with various pulsing parameters (i.e. different current density/pulse duration combinations). This microstructural analysis will focus on how EAM affected grain size, grain orientation, and twinning. The microstructure of the following different specimen types will be compared: deformed EAM specimens, deformed non-pulsed baseline specimens, and undeformed non-pulsed “as received” specimens.

scholarly journals Thermal Diffusivity of Traditional and Innovative Sheet Steels

2010 ◽  
Vol 297-301 ◽  
pp. 893-898
Author(s):  
Elena Campagnoli ◽  
Paolo Matteis ◽  
Giovanni M.M. Mortarino ◽  
Giorgio Scavino
Keyword(s):  
Thermal Diffusivity ◽  
Deep Drawing ◽  
Process Model ◽  
Twip Steel ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Carbon Steels ◽  
Low Carbon ◽  
Low Carbon Steels

The low carbon steels, used for the production of car bodies by deep drawing, are gradually substituted by high strength steels for vehicle weight reduction. The drawn car body components are joined by welding and the welded points undergo a reduction of the local tensile strength. In developing an accurate welding process model, able to optimized process parameters and to predict the final local microstructure, a significant improvement can be given by the knowledge of the welded steels thermal diffusivity at different temperatures. The laser-flash method has been used to compare the thermal diffusivity of two traditional deep drawing steels, two high strength steels already in common usage, i.e. a Dual Phase (DP) steel and a TRansformation Induced Plasticity (TRIP) steel, and one experimental high-Mn austenitic TWIP (Twinning Induced Plasticity) steel. The low carbon steels, at low temperatures, have a thermal diffusivity that is 4-5 times larger than the TWIP steel. Their thermal diffusivity decreases by increasing temperature while the TWIP steel shows an opposite behaviour, albeit with a lesser slope, so that above 700°C the TWIP thermal diffusivity is larger. The different behaviour of the TWIP steel in respect to the ferritic deep drawing steels arises from its non ferro-magnetic austenitic structure. The DP and TRIP steels show intermediate values, their diffusivity being lower than that of the traditional deep drawing steels; this latter fact probably arises from their higher alloy content and more complex microstructure.

Study of the Plastic Deformation in Nanocrystalline and Ultrafine Iron and Carbon Steels

2008 ◽  
Vol 584-586 ◽  
pp. 617-622 ◽  
Author(s):  
Josep Antonio Benito ◽  
Robert Tejedor ◽  
Rodriguez Rodríguez-Baracaldo ◽  
Jose María Cabrera ◽  
Jose Manuel Prado
Keyword(s):  
Grain Size ◽  
Low Carbon Steel ◽  
High Strength ◽  
Carbon Steels ◽  
Low Carbon ◽  
Compression Tests ◽  
Consolidation Process ◽  
Heat Treated ◽  
Average Grain Size ◽  
Grain Size Distributions

Samples of nanostructured and ultrafine grained steels with carbon content ranging from 0.05 to 0.55%wt. have been obtained by a warm consolidation process from mechanically milled powders and subsequent heat treatments. In general, homogeneous grain size distributions were obtained except for the low-carbon steel in which a bimodal grain size distribution was observed when it was heat treated at high temperatures. The stress-strain response has been studied by means of compression tests. Nanostructured materials showed high strength but poor results in terms of ductility. In the low-ultrafine range (mean grain size between 100-500 nm) the three materials showed an increase in the ductility with strain softening. Finally, when the average grain size was close to 1 µm samples showed larger ductility and strain hardening.

Application of Physical Simulation for Developing New Steel Types

2008 ◽  
Vol 575-578 ◽  
pp. 1002-1007 ◽  
Author(s):  
L. Pentti Karjalainen ◽  
Mahesh C. Somani ◽  
Atef S. Hamada
Keyword(s):  
Mechanical Properties ◽  
Stainless Steels ◽  
Physical Simulation ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Carbon Steels ◽  
Austenitic Steels ◽  
Low Carbon ◽  
Modelling Studies ◽  
Electron Microscopes

Processing of a large number of novel steel types, such as DP, TRIP, CP and TWIP, and high-strength low-carbon bainitic and martensitic DQ-T steels, have been developed based on physical simulation and modelling studies. Among stainless steels, guidelines for processing of ultra-fine grained austenitic stainless steels have been created. Physical simulation has been used by employing a Gleeble thermo-mechanical simulator to reveal the phenomena occurring in the hot rolling stage (the flow resistance, recrystallization kinetics and microstructure evolution), and in the cooling stage (CCT diagrams) for carbon steels and in short-term annealing of cold rolled metastable austenitic steels. Connecting these data with microstructures examined in optical and electron microscopes and resultant mechanical properties have improved the understanding on complex phenomena occurring in the processing of these steels and the role of numerous process variables in the optimization of enhanced mechanical properties.

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