So I know I have an exhaust leak in my y-pipe off the header, it’s driving me crazy. It sounds like crap

I took it to 2 muffler shops today and they both said they can’t get a welder in the crack.

It’s right in the valley of the y as seen here (not mine). I was thinking of hitting it with all my wire wheels and using some kind of high temp putty in there for the time being until I can get around to replacing the entire exhaust system. Thoughts on brands or types or even if that type of repair works or not?