Welding anything to AR plate requires the plate to be preheated for the weld to hold, if not preheated the chain or whatever is welded to it will pop off with a shock load and the weld will pull off a thin layer of the AR plate. The plate will need to be preheated to a minimum of 400F in an area of 2 to 3 inches around the intended attachment point for it to be actually welded to the plate. I have fabricated many things out of AR plate and found out the hard way about welding to this material, in welding pad eyes to AR plate for lifting with a hoist to put into position I have seen these pad eyes pop off from having been welded to the AR plate without proper preheating. I suggest just cutting a hole with a plasma or a torch, you will have a much better attachment point doing it that way.