  We study the role of radial migration of stars on the chemical evolution of
the Milky Way disk. In particular, we are interested in the impact of that
process on the local properties of the disk (age-metallicity relation and its
dispersion, metallicity distribution, evolution of abundance ratios) and on the
morphological properties of the resulting thick and thin disks.We use a model
with several new or up-dated ingredients: atomic and molecular gas phases, star
formation depending on molecular gas, yields from the recent homogeneous grid
provided by Nomoto et al. (2013), observationally inferred SNIa rates. We
describe radial migration with parametrised time- and radius-dependent
diffusion coefficients, based on the analysis of a N-body+SPH simulation. We
also consider parametrised radial gas flows, induced by the action of the
Galactic bar. Our model reproduces well the present day values of most of the
main global observables of the MW disk and bulge, and also the observed
"stacked" evolution of MW-type galaxies from van Dokkum et al. (2013). The
azimuthally averaged radial velocity of gas inflow is constrained to less than
a few tenths of km/s. Radial migration is constrained by the observed
dispersion in the age-metallicity relation. Assuming that the thick disk is the
oldest (>9 Gyr) part of the disk, we find that the adopted radial migration
scheme can reproduce quantitatively the main local properties of the thin and
thick disk. The thick disk extends up to ~11 kpc and has a scale length of 1.8
kpc, considerably shorter than the thin disk, because of the inside-out
formation scheme. We also show how, in this framework, current and forthcoming
spectroscopic observations can constrain the nucleosynthesis yields of massive
stars for the metallicity range of 0.1 solar to 2-3 solar.
