Copper will dissolve in solder, so an unplated tip will wear out much faster than a plated one. The plating usually used is iron. Additional plating of nickel, chrome, and tin is often added to improve wetting to the solder and to prevent the iron from rusting.
Most of us have experience with tips that seem to last a long time, then suddenly will develop a pit in the end that grows rapidly. This is because a small hole has opened in the iron plating, exposing the copper core. These holes are usually caused my mechanical wear that breaks through the iron plating. Moving the tip around when using solder wick can easily wear through the iron plating. And never, ever, use sand paper or a file on a soldering tip.
Please note: The use of the word "iron" in this post, refers to the element FE, not the tool used for soldering.