Formation and Structure of Work Material in the Friction Stir Forming Process

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Sladjan Lazarevic ◽  
Kenneth A. Ogata ◽  
Scott F. Miller ◽  
Grant H. Kruger ◽  
Blair E. Carlson
Keyword(s):  
Steel Sheet ◽  
Dissimilar Materials ◽  
Mechanical Interlocking ◽  
Forming Process ◽  
Friction Stir ◽  
Joint Structure ◽  
Work Material ◽  
Formation Zone ◽  
Significant Process ◽  
Geometrical Effects

Friction stir forming (FSF) is a new environmentally friendly manufacturing process for lap joining of dissimilar materials. Fundamentally, this process is based on frictionally heating and mechanically stirring work material of the top piece in a plasticized state to form a mechanical interlocking joint within the bottom material. In this research, the significant process parameters were identified and optimized for Al 6014 alloy and mild steel using a design of experiments (DOE) methodology. The overall joint structure and grain microstructure were mapped as the FSF process progressed and the aluminum work material deformed through different stages. It was found that the work material within the joint exhibited two layers, thermomechanical affected zone, which formed due to the contact pressure and angular momentum of the tool, and heat affected formation zone, which was composed of work material formed through the hole in the steel sheet and into the anvil cavity. Two different geometries of anvil design were employed to investigate geometrical effects during FSF of the aluminum. It was found that the direction and amount of work material deformation under the tool varies from the center to the shoulder.

Mechanical Interlocking of Titanium and Steel Using Friction Stir Forming

2018 ◽  
Vol 792 ◽  
pp. 59-64
Author(s):  
Hamed Mofidi Tabatabaei ◽  
Shun Orihara ◽  
Tadashi Nishihara ◽  
Takahiro Ohashi
Keyword(s):  
Steel Sheet ◽  
Pure Titanium ◽  
Mechanical Interlocking ◽  
Titanium Plate ◽  
Screw Hole ◽  
Microstructural Observation ◽  
Friction Stir ◽  
Hardness Tests ◽  
Dissimilar Alloys ◽  
Novel Method

This study presents a novel method for mechanically interlocking dissimilar alloys of pure titanium with steel through using the principles of friction stir forming (FSF) technique. In present study, titanium plate is placed on top of a steel sheet containing a screwed hole. FSF is conducted on top of the titanium alloy, which produces sufficient heat to plasticize the alloy. This results in a flow of titanium into the screw hole in the steel, due to the plastic deformation, thereby mechanically interlocking titanium with the steel. The mechanical properties of the developed interlock are investigated through tensile and hardness tests and microstructural observation.

Dissimilar Material Joint Strength and Structure for Friction Stir Forming Process

2014 ◽  
Author(s):  
Kenneth A. Ogata ◽  
Sladjan Lazarevic ◽  
Scott F. Miller
Keyword(s):  
Failure Modes ◽  
Dissimilar Materials ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Process ◽  
Experimental Conditions ◽  
Friction Stir ◽  
Automotive Body ◽  
Neck Fracture ◽  
Ultra High Strength Steels

Mass reduction of automotive body structures is a critical part of achieving reduced CO2 emissions in the automotive industry. There has been significant work on the application of ultra high strength steels and aluminum alloys. However, the next paradigm is the integrated use of both materials, which creates the need to join them together. Friction stir forming is a new environmentally benign manufacturing process for joining dissimilar materials. The concept of this process is stir heating one material and forming it into a mechanical interlocking joint with the second material. In this research the process was experimentally analyzed in a computer numerical controlled machining center between aluminum and steel work pieces. The significant process parameters were identified and their optimized settings for the current experimental conditions defined using a design of experiments methodology. Three failure modes were identified (neck fracture, aluminum sheet peeling, and bonding delamination i.e. braze fracture). The overall joint structure and grain microstructure were mapped along different stages of the friction stir forming process. Two layers were formed within the aluminum, the thermo-mechanical affected zone that had been deformed due to the contact pressure and angular momentum of the tool, and the heat affected deformation zone that deformed into the cavity.

scholarly journals Single-Stroke Attachment of Sheets to Tube Ends Made from Dissimilar Materials

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 815
Author(s):  
Luis M. Alves ◽  
Tiago J. Reis ◽  
Rafael M. Afonso ◽  
Paulo A.F. Martins
Keyword(s):  
Numerical Simulation ◽  
Dissimilar Materials ◽  
Mechanical Interlocking ◽  
Forming Process ◽  
Operating Variables ◽  
Sheet Surface ◽  
New Process ◽  
Deformation Mechanics ◽  
Tube Expansion ◽  
Main Operating

This paper presents a new joining method by a forming process for attaching sheets to tube ends. The process consists of two different forming stages carried out sequentially in a single stroke. Firstly, the free tube end is flared by compression with a contoured die, then is squeezed (indented) against the sheet surface to create a mechanical interlocking. The new process is carried out at an ambient temperature and, in contrast to existing joining by forming operations based on tube expansion, it avoids seal welds, tube protrusions above the sheet surfaces, and machining of grooves on the sheet holes to obtain the form-fit joints. The paper starts by analyzing the process deformation mechanics and its main operating variables and finishes by presenting examples that demonstrate its effectiveness for attaching sheets to tube ends made from polyvinylchloride and aluminum. Experimental and numerical simulation work provides support to the presentation.

Mechanical Interlocking of an Aluminum Alloy and SS400 Structural Steel through Friction-Stir Spot Forming (FSSF)

2018 ◽  
Vol 926 ◽  
pp. 17-22
Author(s):  
Hamed Mofidi Tabatabaei ◽  
Ryuji Ishikawa ◽  
Tadashi Nishihara
Keyword(s):  
Aluminum Alloy ◽  
Structural Steel ◽  
Steel Sheet ◽  
Mechanical Interlocking ◽  
Screw Hole ◽  
Microstructural Observation ◽  
Friction Stir ◽  
Hardness Tests ◽  
Dissimilar Alloys ◽  
Novel Method

In the present study, a novel method for mechanically interlocking the dissimilar alloys of A6061-T6 aluminum alloy and SS400 structural steel using friction-stir forming (FSF) is suggested. In this study, the aluminum alloy is placed on top of a steel sheet containing a screwed hole. The present study suggests that friction-stir spot forming (FSSF) can be used to form a mechanical interlock between the aluminum alloy and steel sheet. FSSF is conducted on top of the aluminum alloy, which produces sufficient heat to plasticize the aluminum alloy. This results in a flow of aluminum into the screw hole in the steel, due to the plastic deformation, thereby mechanically interlocking the aluminum with the steel. Moreover, with the proposed method, the authors present a new concept of an easily separable joining of dissimilar alloys. The mechanical properties of the developed interlock are investigated through tensile and hardness tests and microstructural observation.

Production of a Superplastic Vibration-Damping Steel Sheet Composite Using Friction Stir Forming

2016 ◽  
Vol 838-839 ◽  
pp. 574-580 ◽  
Author(s):  
Hamed Mofidi Tabatabaei ◽  
Takahiro Hara ◽  
Tadashi Nishihara
Keyword(s):  
Mechanical Properties ◽  
Steel Sheet ◽  
Superplastic Forming ◽  
Vibration Damping ◽  
Milling Machine ◽  
Mechanical Interlocking ◽  
Friction Stir ◽  
Superplastic Alloy ◽  
Novel Method ◽  
And Diffusion

This study proposes a novel method of manufacturing composite vibration-damping steel sheet with Zn-22Al superplastic alloy using friction stir forming (FSF). Trials of mechanical interlocking of steel sheet with Zn-22Al superplastic alloy using FSF were carried out on a modified milling machine. The results are discussed in terms of residual microstructures and mechanical properties. We concluded that cladding steel sheet with Zn-22Al superplastic alloy using FSF results in superplastic forming and diffusion bonding.

scholarly journals Formability study and metallurgical properties analysis of FSWed AA 6061 blank by the SPIF process

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Payam Tayebi ◽  
Ali Fazli ◽  
Parviz Asadi ◽  
Mahdi Soltanpour
Keyword(s):  
Base Metal ◽  
Strain Distribution ◽  
Thickness Distribution ◽  
Experimental Studies ◽  
Welding Process ◽  
Forming Limit ◽  
Forming Process ◽  
Friction Stir ◽  
Numerical Process ◽  
Tailor Welded Blank

AbstractIn this study, in order to obtain the maximum possible formability in tailor-welded blank AA6061 sheets connected by the friction stir welding (FSW) procedure, the incremental sheet forming process has been utilized. The results are presented both numerically and experimentally. To obtain the forming limit angle, the base and FSWed sheets were formed in different angles with conical geometry, and ultimately, the forming limit angle for the base metal and FSWed sheet is estimated to be 60° and 57.5°, respectively. To explore the effects of welding and forming procedures on AA6061 sheets, experimental studies such as mechanical properties, microstructure and fracture analysis are carried out on the samples. Also, the thickness distribution of the samples is studied to investigate the effect of the welding process on the thickness distribution. Then, the numerical process was simulated by the ABAQUS commercial software to study the causes of the FSWed samples failure through analyzing the thickness distribution parameter, and major and minor strains and the strain distribution. Causes of failure in FSWed samples include increased minor strain, strain distribution and thickness distribution in welded areas, especially in the proximity of the base metal area.

scholarly journals Challenges in the Forging of Steel-Aluminum Bearing Bushings

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 803
Author(s):  
Bernd-Arno Behrens ◽  
Johanna Uhe ◽  
Tom Petersen ◽  
Christian Klose ◽  
Susanne E. Thürer ◽  
...  
Keyword(s):  
Intermetallic Layer ◽  
Dissimilar Materials ◽  
Intermetallic Phases ◽  
Internal Diameter ◽  
External Diameter ◽  
Forming Process ◽  
High Deformation ◽  
Eds Analysis ◽  
Steel Aisi ◽  
Metallurgical Bond

The current study introduces a method for manufacturing steel–aluminum bearing bushings by compound forging. To study the process, cylindrical bimetal workpieces consisting of steel AISI 4820 (1.7147, 20MnCr5) in the internal diameter and aluminum 6082 (3.2315, AlSi1MgMn) in the external diameter were used. The forming of compounds consisting of dissimilar materials is challenging due to their different thermophysical and mechanical properties. The specific heating concept discussed in this article was developed in order to achieve sufficient formability for both materials simultaneously. By means of tailored heating, the bimetal workpieces were successfully formed to a bearing bushing geometry using two different strategies with different heating durations. A metallurgical bond without any forging defects, e.g., gaps and cracks, was observed in areas of high deformation. The steel–aluminum interface was subsequently examined by optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It was found that the examined forming process, which utilized steel–aluminum workpieces having no metallurgical bond prior to forming, led to the formation of insular intermetallic phases along the joining zone with a maximum thickness of approximately 5–7 µm. The results of the EDS analysis indicated a prevailing FexAly phase in the resulting intermetallic layer.

Measurement and Calculation of Elastic Properties in Low Carbon Steel Sheet

2005 ◽  
Vol 495-497 ◽  
pp. 1591-1596 ◽  
Author(s):  
Vladimir Luzin ◽  
S. Banovic ◽  
Thomas Gnäupel-Herold ◽  
Henry Prask ◽  
R.E. Ricker
Keyword(s):  
Carbon Steel ◽  
Elastic Property ◽  
Elastic Properties ◽  
Steel Sheet ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Forming Process ◽  
Element Analysis ◽  
Wide Range ◽  
Carbon Steel Sheet

Low carbon steel (usually in sheet form) has found a wide range of applications in industry due to its high formability. The inner and outer panels of a car body are good examples of such an implementation. While low carbon steel has been used in this application for many decades, a reliable predictive capability of the forming process and “springback” has still not been achieved. NIST has been involved in addressing this and other formability problems for several years. In this paper, texture produced by the in-plane straining and its relationship to springback is reported. Low carbon steel sheet was examined in the as-received condition and after balanced biaxial straining to 25%. This was performed using the Marciniak in-plane stretching test. Both experimental measurements and numerical calculations have been utilized to evaluate anisotropy and evolution of the elastic properties during forming. We employ several techniques for elastic property measurements (dynamic mechanical analysis, static four point bending, mechanical resonance frequency measurements), and several calculation schemes (orientation distribution function averaging, finite element analysis) which are based on texture measurements (neutron diffraction, electron back scattering diffraction). The following objectives are pursued: a) To test a range of different experimental techniques for elastic property measurements in sheet metals; b) To validate numerical calculation methods of the elastic properties by experiments; c) To evaluate elastic property changes (and texture development) during biaxial straining. On the basis of the investigation, recommendations are made for the evaluation of elastic properties in textured sheet metal.

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