Source : Webster's Revised Unabridged Dictionary (1913)

   {Scrap forgings}, forgings made from wrought iron scrap.

   {Scrap iron}.
      (a) Cuttings and waste pieces of wrought iron from which
          bar iron or forgings can be made; -- called also
          {wrought-iron scrap}.
      (b) Fragments of cast iron or defective castings suitable
          for remelting in the foundry; -- called also {foundry
          scrap}, or {cast scrap}.

Source : WordNet®

scrap iron
     n : iron to be melted again and reworked