My anvil is hard ( 59 rockwell ) and my 4 main forging hammers ( 1 1/2 thru 5 lbs ) are hard ( upper 50s rockwell )
If your anvil is the PROPER height for YOU and you hit it FAIR & SQUARE it should not leave any dings.
That is of course if one first rules out Fatigue , too large of hammer , over zealous hammering etc.etc.etc.