Something's wrong with this "analysis". "Pure iron" is very low strength, and chlorine and Sulphur are impurities that would weaken it even more. High strength steels generally contain around a half percent carbon, or more, and virtually no Sulphur or chlorine. At the content listed, the striking head of the hammer would be pounded out like a mushroom.
Yep, and hammers are made that way on purpose. Safer to have it mushroom than splinter off high speed projectiles because it is too brittle. Even when high carbon metals are used for hammers they are annealed to make them softer and prevent fracturing.