Heat treatment of steel

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 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.

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