In article ,
says...
I can't really explain it... it was "red" (starting to turn red), but I
didn't keep it there so it'd be GLOWING red... but I would imagine that it
was a little easier to bend at least than if it was cold.

Estimating temperature by color is very sensitive to the surrounding
light level, but if you saw any red at all you probably did make it a
bit easier to bend the bar.

Scroll down to find a color chart..
http://hypertextbook.com/physics/waves/color/

and a graph of reduction in yield vs. temperature..
http://www.pentoncmg.com/sfpe/articl...pring%2003.pdf

Ned Simmons