Solution:

Purposes of Heat treatment: (Any two 1 mark each)

1) Improve machinability

2) Relieve the internal stresses

3) Improve mechanical properties such as ductility, strength, hardness, toughness, etc.

4) Change in grain size

5) Increase resistance to heat and corrosion

6) Modify electrical and magnetic properties.

7) Change in chemical composition

8) Remove gases