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We test the hypothesis of Berthet (1992) which foresees that Am stars becomegiant metallic A and F stars (defined by an enhanced value of the blanketingparameter Delta_m_2 of the Geneva photometry) when they evolve.  If this hypothesis is right, Am and metallic A-FIII stars need to have thesame rate of binaries and a similar distribution of vsini. From our newspectroscopic data and from vsini and radial velocities in the literature, weshow that it is not the case. The metallic giant stars are often fast rotatorswith vsini larger than 100 km/s, while the maximum rotational velocity for Amstars is about 100 km/s. The rate of tight binaries with periods less than 1000days is less than 30 percent among metallic giants, which is incompatible withthe value of 75 percent for Am stars (Abt & Levy 1985). Therefore, the simplestway to explain the existence of giant metallic F stars is to suggest that allnormal A and early F stars might go through a short "metallic" phase when theyare finishing their life on the main sequence.  Besides, it is shown that only giant stars with spectral type comprisedbetween F0 and F6 may have a really enhanced Delta_m_2 value, while all A-typegiants seem to be normal.Comment: 19 pages, 13 figures, to appear in A&A

Are metallic A-F giants evolved Am stars? Rotation and rate of binaries among giant F stars