  We present the chemical composition of 206 red giant branch stars members of
the Small Magellanic Cloud (SMC) using optical, high-resolution spectra
collected with the multi-object spectrograph FLAMES-GIRAFFE at the ESO Very
Large Telescope. This sample includes stars in three fields located in
different positions within the parent galaxy. We analysed the main groups of
elements, namely light- (Na), alpha- (O, Mg, Si, Ca, Ti), iron-peak (Sc, V, Fe,
Ni, Cu) and s-process elements (Zr, Ba, La). The metallicity distribution of
the sample displays a main peak around [Fe/H] ~ -1 dex and a weak metal-poor
tail. However, the three fields display [Fe/H] distributions different with
each other, in particular a difference of 0.2 dex is found between the mean
metallicities of the two most internal fields.The fraction of metal-poor stars
increases significantly (from ~1 to ~20%) from the innermost fields to the most
external one, likely reflecting an age gradient in the SMC. Also, we found a
hint of possible chemically/kinematic distinct substructures. The SMC stars
have abundance ratios clearly distinct with respect to the Milky Way stars, in
particular for the elements produced by massive stars (like Na, $\alpha$ and
most iron-peak elements) that have abundance ratios systematically lower than
those measured in our Galaxy. This points out that the massive stars
contributed less to the chemical enrichment of the SMC with respect to the
Milky Way, according to the low star formation rate expected for this galaxy.
Finally, we identified small systematic differences in the abundances of some
elements (Na, Ti, V and Zr) in the two innermost fields, suggesting that the
chemical enrichment history in the SMC has been not uniform.
