Looks like a staple remover if I've ever seen one
This is normally how cat venom is collected.
You have to admire his confidence. He sees a thick metal bar and thinks, "I bet I could bite through that".
If your cat does this often to metal chairs it may be because he lacks iron in his diet. You can easily get him supplements or increase the amount of fish based food that you give him. If it is any chair he is doing it to, consider buying a softer chair, perhaps a soft wood like pine, to feed him. I often find that cats prefer to eat chairs mushed up with some milk.
You should find that after a few weeks this behavior should stop.
I had a house guest and they asked me if it was safe to pet the cat. I said, 'Absolutely. Super friendly cat.'
Does it scratch?
Pretty much every time, yes it does scratch. I get scratched many times a day?
Does it bite?
Absolutely, always bites. Pretty deep too! Really hurts!
Why the hell did you tell me it was safe to pet the cat?