Were any composites used on the A340 series? Were any composites used in the construction of the A340? If so, which ones?
Yes!!

The slide shows that composite are used in rear pressure bulkhead and keel beam in addition to other parts.


Source: https://company.airbus.com/dam/assets/airbusgroup/int/en/investor-relations/documents/2008/presentations/GIF2008/gif2008_workshop_composites_hellard.pdf

You can read more:
http://www.lcc.mw.tum.de/fileadmin/w00bkg/www/PDF/Symposium/LCC_Symposium_Havar.pdf