They definitely crack under abuse.

There's plenty of top end brands, but undoubtedly Reed vises were ridiculously heavy duty and are very likely the most durable cast iron vises to exist. Yet things happen. And a more famous top end vise brand is Wilton which can also be destroyed (and Wiltons are definitely top tier vises and many brands like Prentiss or Morgan or Parker are considered to be in the same tier but Reed is generally considered even a step above those).

Cast iron vises aren't meant to be used as presses or to hammer things on. Cast iron is brittle, even though most of those top end vises are made from nodular or ductile cast iron (way stronger than the regular stuff...).

In extremely rare examples, manufacturers used steel to make the vise. But these are a very very niche exception, not the norm, over 99% of cast bench vises on the market use cast iron.

Back when Great Britain was still Great, top of the line Record vises were unlike pretty much anything made before or after them. They made the all steel engineer and heavy duty vise models like the Record no. 518 heavy chipping vise. Very unlikely anyone will ever make a comparable vise. These weigh in at around 250-300lb so you even need a really serious table (preferrably screwed down to the floor or to the wall) to mount it to. Not sure if anyone ever made another bench vise as gigantic as these (and there were plenty of behemoths in history - the Reed 4C is huge but the Record 518 weighs twice as much... I think Hollands and Athol made some huge vises too, and there were some larger Reeds for sure, but of course not steel ones). Casting steel is a very expensive and complex process compared to cast iron, that's why these are so rare. Heck, cast steel anvils are crazy expensive and they're literally just a big chunk of steel, a vise is a bit more complex in comparison... The British empire had the position to make something like that at the time, and while it's of course possible to make them today noone would afford to pay for something like this...

A more common steel vise design is the forged one. Post/leg forged vises are the norm for blacksmiths. For a bench vise, there are also a few options. There's the Matador with plenty of copies of it. But a bit more famous is the Heuer (both with replaceable jaws and also one-piece jaws since the whole thing is forged so the jaws do not need to be removable...). They have a nice range and are designed very smart. Expensive in US but quite a good value in Europe for what you get... with the smart design, I mean a few advantages - it's very slender and has more cross section in the "vertical" way, so you have a lot of space around the jaws. The spindle is between the guide and the jaws, not "in the guide as e.g. in a Wilton so the forces are distributed a lot better. The X profile guide allows for adjustment of tightness, these don't ever need to be sloppy due to this. And the nut is fixed so it does not bind (same on Wilton, but some vises like the Prentiss or Record have the nut held up from the bottom so under really high forces it can turn and bind a lottle bit - of course the top end vises are crazy beefy so this is hardly a problem, but the binding nut is common on almost all cheap vises where it does have a notable effect....).

Sorry, went a bit far with the explanation lol... The cheap vises made of standard lamellar cast iron will crack very fast if you overtighten or hammer on them. The nodular ones are very durable but also suceptible to cracking. Only steel ones don't care about it. The Heuer is very slim and light but it'll bend out of shape and spring back if tightened too much. Or it will get all mangled up and bent but it won't crack (though the spindle would likely snap before that happens too).