  We studied time variability and spectral evolution of the Galactic black hole
transient Swift J174510.8-262411 during the first phase of its outburst.
INTEGRAL and Swift observations collected from 2012 September 16 until October
30 have been used. The total squared fractional rms values did not drop below
5% and QPOs, when present, were type-C, indicating that the source never made
the transition to the soft-intermediate state. Even though the source was very
bright (up to 1 Crab in hard X-rays), it showed a so called failed outburst as
it never reached the soft state. XRT and IBIS broad band spectra, well
represented by a hybrid thermal/non-thermalComptonisationmodel, showed physical
parameters characteristic of the hard and intermediate states. In particular,
the derived temperature of the geometrically thin disc black body was about 0.6
keV at maximum.We found a clear decline of the optical depth of the corona
electrons (close to values of 0.1), as well as of the total compactness ratio
lh/ls. The hard-to-hard/intermediate state spectral transition is mainly driven
by the increase in the soft photon flux in the corona, rather than small
variations of the electron heating. This, associated with the increasing of the
disc temperature, is consistent with a disc moving towards the compact object
scenario, i.e. the truncated-disc model. Moreover, this scenario is consistent
with the decreasing fractional squared rms and increasing of the noise and QPO
frequency. In our final group of observations, we found that the contribution
from the non-thermal Comptonisation to the total power supplied to the plasma
is 0.59+0.02/-0.05 and that the thermal electrons cool to kTe<26 keV.
