Mr. Stefan, the corrosion is minor and slightly on the surface which can be removed in any way you see fit, easily. Will not spoil the product assuming all rinsing and removal of the rust is followed. It is soft to begin with but annealing is always a good idea for any wire being used. Because I...
To add to Mr. Archie's post, I used salt water to dip in, the corrosiveness of the sodium chloride will start the rust procedure in a matter of minutes........pap
I've used mild steel tie wire the rusty stuff to fix pits,grinding gouges, and weld tracks in alot of pipe before. Might not be what you all want to hear but it worked for me for decades. papand passed x-ray also