Fe415 is a grade of High Strength Deformed Steel Bar for Concrete Reinforcement. This Grade has been specified by Bureau of Indian Standards (BIS) in a documented standard IS 1786:2008, which a revised version is IS 1786:1985. The number 415 indicates that the Yield Strength (tensile strength when it is subjected to elongation) of steel is 415 N/mm² the bars are designed and manufactured to have.
The abbreviation Fe stands for Ferrous material and also Fe means Iron.
Similarly Fe250, Fe415, Fe500, Fe550, Fe600. The numbers 215, 415, 500, 550 and 600 tell about this Yield Strength in N/mm² the bars are designed and manufactured to have.