The grid fins on the outer cores are aluminium, the centre core is titanium. Newer Falcons will have titanium grid fins (the outer cores have already flown once

The grid fins on the outer cores are aluminium, the centre core is titanium. Newer Falcons will have titanium grid fins (the outer cores have already flown once before) Edit. Looking closer I'm wrong - the titanium grid fins are on the side boosters and the the centre core is aluminium