I'd hate for you to hurt your hand...
Yes, it is easy to do, if not dangerous.
Cast iron is extremely brittle and has very little tensile strength. But product manufacturers take this brittleness seriously, and devise ways to form their product in ways to compensate for poor tensile strength. So, ribbed or uneven surfaces, or shapes that form circles or arches, are often used to protect the product from damage. That means it will be hard to find a length of cast iron that is suitable for breaking.
Other metals - particularly the more "softer" types, like copper, aluminum, and zinc, are easier to come by, but they do not break - they bend. And harder metals like iron and steel are even easier to come by, and are not only harder to break, they're harder to bend as well.
A note about cast iron: it is dangerous to break, as it can do so in shards. Try this with a cast iron skillet, and that may land you in the hospital requiring stitches and tetanus shots.
I have seen it done but I seriously have to wonder about the metal. Metal can be very brittle if processed to be brittle.
This guy is breaking metal with his head. As you can see the piece of metal is also long which lets him incorporate some physics as well to facilitate the breaking. While I don't underestimate their leve of conditioning there is also a good amount of 'know how' with these types of feats and doing it wrong / not knowing how can result in serious injury:
Sure, why not, give it try.
No
a friend of my brother once broke a rock this way. i wonder if you can do the same with metal.
