Robert_White: I worked for a time at the same foundry that my father (and Clint Eastwood!) worked at, Pacific Car & Foundry (Renton, Washington).
They made train cars, frames, axles, trucks for the wheels and axles and train wheels!
The trick to castings which I had something to do with, is many of the parts I dealt with were cast in molds then got heat treated in ovens for various amounts of time and then quenched in certain oil baths and some treated again and quenched again.
IF... you think cast iron pieces are not strong go take a bite out of a railroad car wheel!
Cast iron CAN be made into incredibly hard/strong items.
Hold into the wind
VarmintGuy