Unlikely but not impossible. In modern ecosystems, it's very rare for predators to routinely take on prey much larger than themselves. Foxes mostly take smaller animals like rodents and birds; Lions, which hunt in pack, mostly take animals like zebra that are about the same size as them. After all, why WOULD a lion risk injury or death by participating in an elephant hunt if there are antelope available? For the same reasons, carcharadontids would certainly have preferred smaller prey when it was available â which would have been almost always.
That said, there are rare occasions when packs of lions, starved of easier food, will collaborate to take down an elephant, despite the very real danger. It's possible that starved carcharadontids, if they couldn't find other prey animals, might become desperate enough to risk taking on a fully grown titanosaur. But I certainly can't see them specialising in such a hazardous lifestyle.
-- Mike.