My understanding is that pretty much all steel production uses heat during the alloying/production process, whether it's called "heat treating" I'll leave to the experts. Brazing with a silver (56% being the most common) can result in a very strong attachment with nearly zero steel strength loss, UNLESS one overheats the joint while trying to braze. Which is why we suggest enough practice to be able to recognize this and do something about it before it gets too much.

When practicing I also suggest going too far with the heat to find out what that looks like and how to correct for it before it gets too bad. I am generally more comfortable being driven in a car by someone who has played in a snowy parking lot than one who is afraid of skidding and never learned about it. Andy