Heat treatment of steel
Heat treatment of steel:
The properties of steel are modified on heat treatment:
(1) Annealing: In this process, steel is heated to a bright red heat and cooled slowly. By annealing, steel becomes soft.
(2) Hardening: when steel is heated to a bright red heat and cooled suddenly by dipping in oil or water (quenching) hard and brittle steel is obtained.
(3) Tempering: When steel is heated to a temperature much below redness and cooled slowly, the steel obtained is neither so hard or so brittle.
(4) Nitriding: In this case the steel is heated in an atmosphere of ammonia so that the surface is coated with hard iron nitride.