What material to use for geared shaft

[Pete O]

The plan for removing the stuck shaft from the worm gear worked a treat, gripped the worm gear in some makeshift soft jaws (some strips of 2mmx x20mm aluminium flat bar between the chuck jaws and the workpiece), drilled out to 5/8" which was just starting to break through the base of the keyway. Then used a punch and bush to drive the shaft out, came out very easily. You can see here a section where it has galled badly, I'm thinking perhaps a chip got carried into the bore, anyway not much point trying to guess what happened, it is what it is and just has to be put right.
   
   

There is of course a corresponding galled section in the bore of the worm gear, nothing a bit of a hone can't cure I'm sure. I'm much happier with the stuck shaft out of this and the gear intact.
   
   

You guys have given me some heart that the gearbox housing may be salvageable, I'm thinking it can wait until my furnace is finished and I can cook the oil out of it then weld it. In the meantime the mill will be operable but without any power feeds, better than no mill at all by a long way.
In the meantime I'll shop for some shaft steel as suggested, weld a thick disc onto it for the flange, I'm thinking I can mount the shaft between centres and use a dial indicator to check for deformity once the flange is welded on, keep adding a bit of weld to the outside of the bend until it's straight again.