I did lay down a TIG bead of mild steel filler rod on the side of a junk rotor. I was trying to determine if I could fill in some volume in the combustion chambers.

I then beat the daylights out of the weld area, and used a chisel on the bead trying to make it fail. It held fine. Welding them up might work. Not a very hard material, and easy to damage the fine detail areas around the corner seal holes. They are cast of (not quite steel) a free machining something or other. You could have the metallurgy done, and then tell us what it is. Lynn E. Hanover