Civil Engineering Reference
In-Depth Information
Fig. 3.4
Experimental
flow stress results of room
temperature behavior
for preceding stationary
electrical testing
Fig. 3.5
Experimental EAF
flow stress results for single
pulse application of electrical
current during incremental
forming
sinks. As a result, this was seen by the material yield strength not being signifi-
cantly affected by electrical pre-treating; however, some difference was observed
once dislocation motion began.
Additionally, the EAF incremental tests also agree with this effect. As shown
in Figs.
3.5
and
3.6
, the application of current had a significant effect on the yield
strength of the material without affecting the microstructure. This directly aligns
with the theory of localized “hot spots” which allow for dislocation annihilation as
a result of enhanced diffusion directly surrounding the dislocation. This is in con-
trast to the electrical pre-treating where there was little effect on the material yield
point. For the EAF incremental tests, there was a much greater driving force for
dislocation annihilation due to the increased amount of lattice strain present. Thus,
a larger amount of dislocations were removed and the stress of the material was
reduced which equates to the reduced yield point.
