Heat does a lot of harm to a bar but I have never seen heat bend the bar. People bend bars. Improper cutting technique, pinching and wrenching. When you watch a guy pinch the saw, the first thing he does is try to pull it out before the chain stops spinning. When it doenst pull out he tries harder and harder. This is where bars bend. Wedges and a little encouragement from the boss can solve this rather simply. Tell them it the saw pinches, get a wedge or another saw.
Heats primary cause in a bar is a dull chain or over tention. Many people cant tell the difference between a sharp and dull chain, or they just dont care. If my saw is not cutting exactly the way I want it to I stop and sharpen it. If sharpening doesnt fix the problem then I look at the bar for burs.
Its all in how you train your guys, and how much time you give them to complete the job. If you are rushing them constantly then they will wrench on that pinched saw, or not sharpen the dull one. If you give them the time and encouragement too take care of the saws they will. My crane operator at my old job used to have files and a saw at his station almost all the time, and our saws were never dull.