Forming Process of a 5083 Aluminium Alloy. Constitutive Model Covering a Large Range of Temperature

Both electrically assisted tension (EAT) and thermally assisted tension (TAT) tests were performed on SS304 and pure copper to decouple the influence of elevated temperature from electric current on flow stress and ductility. It is found that the reduction on flow stress and ductility of SS304 are more dependent on the elevated temperature than electric current, but electric current has a stronger effect by 10% on reducing flow stress and ductility of pure copper than the elevated temperature does. As the flow stress and ductility of two metals are related to the dislocation evolution, a constitutive model considering both storage and annihilation process of dislocation was established to describe the effect of electric current and temperature on dislocation movement. It is found that electric current accelerated the annihilation process of dislocation in pure copper up to 20% in EAT compared with that in TAT, but such phenomenon was rarely observed in SS304. Furthermore, attempts have also been made to distinguish the influence of elevated temperature with that of electric current on microstructure evolution and it is also found that the formation of [111] crystals in pure copper is nearly 10% less in EAT than that in TAT.

Download Full-text

Electromagnetic Metal Forming

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1965_180_013_02 ◽

1965 ◽

Vol 180 (1) ◽

pp. 93-110 ◽

Cited By ~ 15

Author(s):

K. Baines ◽

J. L. Duncan ◽

W. Johnson

Keyword(s):

Aluminium Alloy ◽

Metal Forming ◽

Strain Distribution ◽

Eddy Currents ◽

High Rate ◽

Process Efficiency ◽

Primary Circuit ◽

Forming Process ◽

Current Frequency ◽

Thin Walled

Some results of an experimental and theoretical investigation of the dynamic forming of thin-walled tubes and flat circular diaphragms by the electromagnetic metal forming process are given. The paper is divided into two parts. Part 1—The magnetic forming process is described and its use as a production technique is discussed. The process is a high strain-rate technique suitable for forming relatively light gauge material; the forces causing deformation result from the interaction of the current in specially constructed coils and the resulting eddy currents induced in the workpiece. The source of energy is a capacitor bank which can be discharged rapidly through the work-coil. The experiments described were performed using a specially constructed 16 kj discharge unit. The method of constructing work-coils and the failures experienced with these coils in service are described. Thin-walled copper and aluminium tubes were expanded by means of internal solenoidal work-coils of various lengths. The strain distribution and forming efficiency is presented, together with results showing the variation of process efficiency with changes in the primary circuit parameters. The strain distribution for a circular aluminium alloy diaphragm bulged by means of a flat spiral coil is given. Typical primary current waveforms are given and the changes in waveform and discharge current frequency due to different workpiece materials and changes in primary circuit parameters are indicated. Part 2—An attempt is made to determine theoretically the forces acting on one of the aluminium alloy tubes expanded and described in the work of Part 1. The currents in the work-coil and workpiece are calculated using the experimentally determined current waveform and the calculated value of workpiece inductance. A rudimentary method is developed for relating pressure on the workpiece to the primary and secondary currents and, using this, the radial motion of the tube is predicted. Although the analysis involves the use of a number of simplifications and approximations, the theoretical results obtained are of the same magnitude as would be expected by reference to other high-rate forming processes.

Download Full-text

Effect of Friction Stir Forming Process Parameters on Mechanical Interlock between A5083Alloy and Ultra-Thin Stainless Steel Strands

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.858.27 ◽

2020 ◽

Vol 858 ◽

pp. 27-32

Author(s):

Hamed Mofidi Tabatabaei ◽

Keita Kobayashi ◽

Takahiro Ohashi ◽

Tadashi Nishihara

Keyword(s):

Stainless Steel ◽

Aluminium Alloy ◽

Alloy Composite ◽

Forming Process ◽

Cross Sectional ◽

Bending Tests ◽

Friction Stir ◽

Specific Strength ◽

Eds Analysis ◽

Grain Distribution

Fibre-reinforced materials have gathered attention because of their significant properties such as heat resistance, abrasion resistance and specific strength. The present study proposes a new method of joining stainless steel strands with an aluminium alloy using friction stir forming and analyses the formation of a fibre-reinforced aluminium alloy composite material. Mechanical interlocks between the strands and the aluminium alloy are evaluated based on cross-sectional microstructure observations and EDS analysis. The tensile test indicated an increasing tendency of strength by increasing the number of strands and bending tests showed that higher strength is achieved in rare bend because of inhomogeneous grain distribution after friction stir forming (FSF).

Download Full-text