When in Catia V5 you can save your CATPART or CATProduct file as a .stp file (STEP File). After you save it > Open AutoCAD > Open a blank drawing file > select Import from the file menu > Select your .stp file to import > wait for it.
I have a 150mb .stp file and it took AutoCAD almost 20mins to process it but it does work. Just be patient.
save CATIA file CATpart > open new drawing in CAD> TYPE imp(short key for import) and select file type as CATproduct thats all wait few seconds