Best metal for a chuck wrench?

[Suzuki4evr]

I would use 4140HT.

What he said

 

[FOMOGO]

I just made one from some 1/2" round and square stock from the scrap pile. Milled the square to 7/16 and welded it to the 1/2 round. About a ten minute job, might try hardening it latter on, but hard to imagine really needing it. Mike

 

[sdelivery]

I wish mine were a standard extension size, I would have done the same thing and called it a day.

When they would run to Maintenance (me) with a broken chuck wrench a socket wrench extension was always my first go to.
Weld a handle of some convenient scrap on it for a handle and send them on their way. Never had one fail in thirty years.....