  Analysis of directed flow ($v_1$) of protons, antiprotons and pions in
heavy-ion collisions is performed in the range of collision energies
$\sqrt{s_{NN}}$ = 2.7--39 GeV. Simulations have been done within a three-fluid
model employing a purely hadronic equation of state (EoS) and two versions of
the EoS with deconfinement transitions: a first-order phase transition and a
smooth crossover transition. The crossover EoS is unambiguously preferable for
the description of the most part of experimental data in this energy range. The
directed flow indicates that the crossover deconfinement transition takes place
in semicentral Au+Au collisions in a wide range of collision energies 4
\lsim\sqrt{s_{NN}}\lsim$ 30 GeV. The obtained results suggest that the
deconfinement EoS's in the quark-gluon sector should be stiffer at high baryon
densities than those used in the calculation. The latter finding is in
agreement with that discussed in astrophysics.
