A3. Experimental results
3.1. Mechanical behavior
Typical true stress.true strain curves are shown in Fig. 1
for temperatures ranging from 250 to 570 .C. The ƒÐ.ƒÃ curves,
which are representative for all testing conditions, exhibit
a well-defined steady-state flow after a very short transient
stage of plastic deformation (ƒÃ < 0.1).
Fig. 2 shows a plot of the steady state creep rate against
strain obtained from the uninterrupted test (curve I) and the
stress-change test (curve II). It is seen that the creep curve I
also exhibits a very short stage of primary creep. Steady-state
flow was attained at true strain values over 0.004. During the
stress change tests a new steady-state was achieved after a
very short transient stage (Fig. 2, curve II).