do weight distributing bars weaken with age?

My original hitch head egged out where the springs bars attached. I was towing a heavy bumper pull toy hauler and got about eight years out of the head before I had to replace it. I am still using the same bars and have not measured a diameter difference compared to new ones. My old hitch head is now dedicated for towing dead tongue weight - I have it set up at a different height so I do not need mess with my WDH setup when I occasionally tow a lighter trailer.