Whats up with these exhaust valves?

There were no additives used. Engine was broke in on sunoco 110 and switched to E85. I got to scratching some of the "blisters". Comes off like a chrome plating. Competition products says they are 21-4N stainless. Chrome plating is used in the description so I can only assume thats what it is. Its hard stuff to scratch off. Thanks for all the replies guys.