Undo the fixings, though, on those old blacksmith made items, and they'll be seriously corroded, particularly at the point where they emerge from the wood. I don't think they survive for so long because of any inherent resistance to the tanins, but because of their size. I'll happily use mild steel coach screws in oak, but they're 18mm or so in diameter, with huge threads. They are rusty in no time, but the damage only penetrates so far, and with a big fitting that's not far enough to critically undermine the hold it has. With a small item like a normal screw, the same amount of corrosion spells the end of it. I've removed literally hundredweights of old iron and steel fixings from both ancient oak and new oak over the years, and particularly in the last 5 years, so I am pretty confident in what I recommend with regard to modern fixings in oak. Screws, nails......stainless, brass, copper, or very big cut nails. Visible bolts etc, ditto (not copper, obviously). Hidden bolts, carriage bolts, coach bolts/ screws....galvanised MS is fine, so is bright shiny steel. They'll corrode, but they'll hold.
