1. The main purpose of heat treatment of steel is to change:
(A) Mechanical properties
(B) Chemical composition
(C) Physical composition
(D) None of these
2. Which of the following element in steel directly affects the critical temperature of the steel to be heat-treated:
(A) Phosphorous
(B) Sulphur
(C) Manganese
(D) Carbon
3. The temperature and carbon content at which eutectoid reaction occurs in iron-carbon equilibrium diagram are:
(A) 723°C and 0.02% C
(B) 723°C and 0.80% C
(C) 1130°C and 0.80% C
(D) None of these
4. The crystal structure of Austenite is:
(A) CPH
(B) B.C.C
(C) F.C.C
(D) Tetragonal
5. Lower critical temperature of all steels are:
(A) 1140°C
(B) 723°C
(C) 910°C
(D) 1500°C