Left an old chain around a tree years ago before I had a dog pen. Used it to chain the dog while I opened the gate to get out front to cut grass. I manged to dig all the chain out. Will it live or will it topple at some point?
Honestly, probably should have just kept the chain there, the tree would have eventually grown over it
But I would see if you can get the tree treated for insects to minimize the chance for it dying from disease/pests.
Not sure about something as narrow as the wound by a chain, but I know if you want to kill a tree, you tear a ring around the bark. All the nutrients and water from the soil have to get to the tree and that's how they get up there.