Applications of Electrically Assisted Manufacturing - Electrically Assisted Forming - page 289

Fig. 11.37 Upsetting specimens compressed at 20 A/mm 2 with varying platen speeds [ 17 ]
11.4.2 Tension
There has been a lot of experimental work on EAM in tension over the past decade.
The first work will discuss the first attempts of applying a constant electrical cur-
rent to a uniaxial tensile process, in which it was determined that electrical appli-
cation parameters played a role in formability improvement [ 18 ]. The second work
describes a technique of applying electricity to tension in a “pulsing” form, rather
than being applied continuously, which generated better results [ 19 ]. Further, an
experimental work is explained, where different aluminum alloys with different start-
ing microstructures were tested with various electrical application parameters [ 20 ].
Finally, the last work explains a relationship between some of the electrical appli-
cation parameters and balances between each of these parameters that will result in
optimum formability for a uniaxial tension process on a magnesium alloy [ 21 ].
11.4.2.1 EAM Application Methods for Different Deformation
Processes
In 2009, Ross et al. [ 18 ] studied the effect of a continuous current on the same metals
as Perkins, now for uniaxial tension tests. It could be concluded that the yield strength,
flow stress, and elastic modulus were all reduced. Also, because of strain weakening,
the overall energy of deformation was decreased. However, one important finding of
this research was that, due to the continuously applied current, the achievable elon-
gations of the specimens decreased (an opposite effect of using continuously applied
current in compression), as shown in Fig. 11.38 . This led to experimentation with
pulsed electricity, rather than leaving it applied continuously, for tensile applications.