I beg to differ.
You will have no problem bringing the bolt as check-in.
I guarantee you though that TSA will want to open up your bags to look at it.
Carry-on may not work, because you could probably stop any terrorist with the bolt.

I travel with tools and hardware all the time. Samsonite won't cut it. Get a Pelican so that the things don't blow through the sides of your luggage.

I know a Swiss chef who served a resort in the Maldives. He brought a good-sized 20 lb mortar & pestle (think bowling ball) in his carry-on from Thailand to the Maldives. My concern is that such a heavy item is put in the overhead--better not be over my head! But if they don't know, nobody cares as long as it fits.