Got a 250 HP motor in with a rotor whose drive shaft was running out about .0065 at the end.  It came to the shop with complaints about excessive vibration.  I straightened it yesterday to .001 TIR along its length with a torch.  It took heating it three times to get it there.  All three spots were heated to a dull red and quenched.  I've used this method a few times and have sent the things out without doing anything else.  However, this particular customer is rather picky about documenting everything and may have desk jockey engineers looking at the details.

Should I spin the thing in the lathe and heat to a uniform temper of say 500 degrees F just to equalize any stresses and soften any hard spots?  The shaft is a medium carbon steel, likely 1045 or similar.  Would tempering likely undo my straightening job?

The factory assembly of the rotor shows significant heat bluing near where the rotor iron is installed.  Now whether that is a by product of a hot lamination stack cooling on the shaft, or casting the aluminum end rings, I'm not sure.  Either way, there seemed to be little concern about that level of heat on the shaft.

Did you straighten with heat and pressure or just by heat shrinking?

1045 isn't air hardening and dull red is sub critical so I don't think you spot hardened it.

A uniform temper could relieve your straightening job. I would leave it be.

Thanks for the reply.  I only heat straightened but with a wet rag quench.  Those spots did become a bit harder, but still could be cut with a file. The motor went back together today, and I did not try to temper.

The biggest concern I'd have would be grain growth, but that depends how hot and for how long, and from what it sounds like I don't think you approached anything that would have balooned the grain boundaries in the effected areas.

If the guy is picky and if this may bite you in the ass later, offer him a new replacement quotation, or have him sign a disclaimer on the repair. 

Don't worry about it. If this is a 250HP motor that shaft is quite large. It's not going to break, and being 1045 it's doubtful that it would have even been heat treated in the first place. I have made many shafts this size and considerably larger - and straightened them also - in the press and with a torch. Never bothered to try anything further than straightening. If heat treat and grain condition were critical they would have had you make a new shaft. If this were 4140 or similar and engineered within an inch of its life then it might be a different story.

Edit: just noticed this was an old post. N/M!