It would take far to long to explain here,and i dont type fast.If your the type to explore this kinda stuff deeper,Google metalurgy.Or however one spells it.Very informative stuff for enquiring minds.
I perhaps mistook your inquiring mind for an arguementive type,but it seems the latter is all too common here.I see you also enquired in frame builders and got same answer as here!
As someone has already said its not like you will see any stress cracks starting inside steer head tube making it too risky, for me anyhow.Probably would have been better to not straighten it out if only 2 degrees.Putting another bend in it just increases risk.