Method of Heating
1. Non-Ferrous Metals ·such as duralurnin and aluminium are heat treated in at salt bath. This
is a mild steel bath containing a mixture of potassium and sodium` nitrates, which is
heated by gas, oil or electricity.
Heat Treatment of Duralumin‘
2. Annealing. This operation permits the material to be worked and bent. Duralu-
min is annealed in a salt bath at a temperature between 36O C and 400%] and then quen-
ched in clean cold water.
3. Neematizing. Duralumin is normalized to relieve stresses andistrains set up by ‘
working. Duralumin is normalized in a salt
505"C and then quenched clean water.
NOTE : Normalized. iduralumin gradually becomes harder and stronger (age-
hardens) during the three tor four days after treatment. ”
Heat Treatment of Aluminium?
4. Annealing is the only heat treatment applied to aluminium. Sheet which has, been
"nardened by cold working can berestored to a soft ductile condition by heating to about ‘
360°C,.then quenching_in water or cooling in the air. ,
Heat Treatment of Copper and Brass`
(VST Copper and Brass very quickly harden, These can be softened by anneal-
ing. Heat the metal to dull red heat (650C) and quench it ‘ in water et allow it to cool
in the air. Repeat the process as required.
Heat Treatment of Magnesium Alloys
6· Magnessium sheet can be worked for simple operation, but if heated to
a temperature of 300°C, it bends easily,