Pila bending at the shank

[Flavivs Aetivs]

"The Real Wrought Iron Company" and Chris Top can supply wrought iron bar which may not be perfect but is probably close enough if you want an "iron" pilum head to try out...

Which is nothing like what the Romans used. Modern steel isn't either, but the Romans used steel in the range of what is ideal for swords (and always has been) which is like 50-60 or 10-45 or something.