Q1. Heating the Hypo-eutectoid steels to 30°C above the upper critical temperature line, soaking at that temperature and then cooling slowly to the room temperature to form a pearlite & ferrite structure is called
Q2. Pick out the wrong statement.
(A) A ferromagnetic material becomes paramagnetic above the ‘Curie temperature’
(B) Permanent magnets are made of hard materials, whereas electromagnets require soft magnetic materials
(C) Soft magnetic materials (e.g., pure iron) have higher permeability and low hysterisis loss and coercive forces
(D) Tungsten steel and alnico are not hard magnetic materials
Q3. The elastic strain in copper is due to the
(A) Motion of dislocations
(B) Stretching of atomic bonds
(C) Breakage of atomic bonds
(D) None of the above
Q4. The difference in one unit of Rockwell hardness number corresponds to a difference in the depth of indentation of __________ mm.
Q5. Transformation range for ferrous material is the temperature interval during which __________ is formed during its heating.
Q6. Pick out the wrong statement.
(A) Both annealing and normalising release the internal stresses of the material besides improving the mechanical properties
(B) Low carbon steel does not respond to the heat treatment for hardening of the material, hence it is subjected to case hardening or surface hardening processes like cyaniding, carburising, nitriding etc., which produces high carbon outer layers resulting in increase of surface hardness
(C) Induction hardening and flame hardening techniques are also used for surface hardening
(D) Martempering of a material is a hardening process
Q7. Which of the following is not a charge material for cupola?
(B) Iron scrap
(C) Iron ore
(D) Pig iron
Q8. Electrical conductivities of semi-conductors are of the order of __________ ohm/cm.
Q9. With increase in steam pressure, its specific volume decreases
(A) Rapidly first and then slowly
(C) Slowly first and then rapidly
Q10. Maximum hardenability of steel depends upon its
(A) Chemical composition
(B) Carbon content
(C) Grain size
(D) Alloying elements content