2.3 Uniaxial Tensile Test of MTP and SSFS specimens
Prior to high temperature LCF testing, uniaxial tensile test had been
performed on MTP-3 and compared with SSFS testing results at 20 °C and
600 °C, respectively, in order to demonstrate the capability of the
testing technique. The miniature uniaxial tensile tests were conducted
using the testing rig as introduced in Section 2.2 (see Fig.2c). The
applied displacement-rate for the MTP-3 specimen was under a constant of
strain-rate of 0.01%s-1 during the tensile testing,
which is consistent with the loading process of the SSFS tensile
testing1. The applied torque on both screw bolts were
keep the same with a value of 0.5Nm to avoid any torsions during testing
and provide enough clamping force. Noted that the displacements were
measured at the ends of the fillet radius regions since it is difficult
to accommodate the extensometers into the very limited region. As can be
seen from the testing results in terms of engineering stress-strain
curves estimated from the initial cross-section area and displacement
shown in Fig.3, the tensile responses from MTP-3 specimen follow the
typical temperature-dependent stress-strain behaviors, for example,
higher ultimate tensile response and lower ductility at 20 °C compared
with these at 600 °C. More importantly, almost identical trend can be
achieved, which indicates the possibility to make the comparisons of
high temperature LCF and CF tests between MTP and SSFS specimens.