Civil Engineering Reference
In-Depth Information
2.2.4 Electroplasticity and Electromigration
The above-described effects are shown experimentally to be due not just to bulk
thermal influences. There is an effect on material flow stress that appears to be due
solely to direct electrical influence, beyond what would be expected from tempera-
ture effects. This electroplasticity effect is one of the key phenomena associated with
EAF, and what we attempt to describe in the modeling chapters in later chapters.
2.3 Broader Impacts of EAF
The applications (or industries) which could use EAF will be discussed first, fol-
lowed by potential users of the EAF thermo-mechanical predictive models.
2.3.1 Automotive and Aerospace Industries
Like other formability-enhancing manufacturing techniques, EAF is not the opti-
mum technique to use for all metals or all part designs. Specifically, during EAF,
excess electrical power needs to be supplied to the workpiece, which does not
always make it the most efficient process. However, the results from using EAF
are significant and it may be one of the very few techniques that allow efficient
forming of particular metals. For this reason, EAF should be used to form metals
and alloys which are currently not able to be formed to great lengths or require
excessive heating or annealing. The EAF technique would act as a gateway for
these metals to be used in industry. Two metals whose formability improves tre-
mendously using EAF are magnesium and titanium, which are targeted by the
automotive and aerospace industries, respectively.
With the rising fuel and operational costs, the automotive and aircraft industries
are becoming more weight-, performance-, and efficiency-focused. One way to
achieve all three variables is by lightweighting. In this technique, lighter and stronger
materials are used instead of the heavier carbon steels mainly used today. Magnesium
is a desirable material for the automotive industry, where it is currently used in mainly
cast components due to its very low formability. On the other hand, titanium is popu-
lar for use in aerospace applications, but the manufacturers constantly struggle with
the poor formability and high required forming forces of this material. Again, previ-
ous research has shown that EAF significantly improves the formability of titanium,
which will increase the number of potential aerospace applications for the alloy.
