Re-bending somthing work hardens it and it gets stiffer and harder,
I dont know what you do with your tension wrenches but ive never bent one more than a few mm even being very rough with them,
Heating is not required to bend or twist them and it is not needed to make them stiffer, they dont need to be stiffer, if you want a stiffer wrench dont twist it,
Ive thrown this quick vid together to show jsut what i mean, the rebending i did on this is nowhere near what a normal one would need if slightly bent out of shape but if it was bent and then reset the strength is unaltered and if anything its made a slight bit stiffer in the bend,
Twisting is the same, you can twist them all you like, nothing will change,
You are surely useing far too much tension on your locks if a normal wrench is being so deformed that you need to make it stronger or at least thik you are making it stronger which as matter of fact you arent as you dont harden stainless like that, what you are doing is making it softer but a bit more brittle, the brittleness is maybe giving you the impression of it being harder and you arent putting enough pressure on them to actualy break,
Just to add, i am still on my original pick set and wrenches that i bought ages ago, i have bent a couple of rakes but otherwise all, original and present,
Anyway when it takes 14 seconds to make a twist tension wrench whats the issue with them lasting longer,

Of course you can do what you like with your stuff but please dont mislead others with incorrect statements,