Iron and steel

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Across
  1. 4. strongest type of steel
  2. 7. Extraction of iron from its ore
  3. 8. Metal that coats the 3rd word of the crossword
  4. 11. chief ore of iron
  5. 13. Transformation of iron and used by car producers
  6. 14. made from coal and almost pure carbon
  7. 15. chemical element used to recycle steel/iron
Down
  1. 1. its chemical structure is CaCO3
  2. 2. most soft type of iron
  3. 3. type of iron used for steel
  4. 5. mixture of nickel-chromium plus iron
  5. 6. impure iron
  6. 9. mixture added at the top of the furnace
  7. 10. chemical element which strengths steel
  8. 12. Composes the 6% as an element of the earth’s outer layer