Heat Treatment of Metal

heating and cooling metals to change their properties

Work Hardening

increases strength

but makes more brittle

annealing

heating metal up after hardening to make it soft again - less brittle

case hardening

carbon added to the outside case of steel

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  1. Heat steel - red hot
  1. Dip in compound (carbon)
  1. Heat again and then quench in cold water

Tempering

deforming / hitting - changes the molecular structure

easier to work with

e.g. Jewellery

heat metal

quench in oil

makes it less brittle