heating 5/16" shrouds

[berwick]

I have seized bolts that hold the end the spreader together (the old aluminum spreader and SS bolts) I cannot remove them and the SS wire is not moving through the ends of the spreader because of the corrosion. I would like to apply heat to the bolts but am worried about this heat transferring from the bolts to the 5/16" wire and weakening or tempering the wire. How much of a worry is this? Can it take some heat?

Thanks, Richard