Solution of Assignment 7
1. The variety of cast iron that has maximum hardness is
(a) Gray Iron
(b) Malleable iron
(c) Ductile iron
(d) White iron
2. The element which is harmful for nodularization to take place while making ductile iron
castings is
(a) Sulfur
(b) Carbon
(c) Silicon
(d) Phosphorus
3. To produce sound steel castings, the molten metal must be thoroughly killed. In other words,
molten metal should be
(a) Overheated
(b) Deoxidized
(c) Decarburized
(d) Desulfurized
4. The variety of cast iron that has maximum ductility is
(a) Gray Iron
(b) Mottled iron
(c) White iron
(d) Malleable iron
5. Solubility of gases in the melt increases as the temperature
(a) Increases
(b) Decreases
(c) Remains constant
(d) Remains unaffected by pressure
6. Use of nucleating agents promote formation of
(a) Fine grain structure throughout the casting
(b) Coarse grain structure throughout the casting
(c) Fine grains at walls and coarse grains at center of casting
(d) Coarse grains at walls and fine grains at center of casting
7. Which one of the following is used as a grain refiner in Magnesium alloys?
(a) Sulfur
(b) Silicon
(c) Zirconium
(d) Phosphorus
8. In low carbon steel carbon percentage is
(a) less than 0.2%
(b) In between 0.2% to 0.5%
(c) In between 0.5% to 0.7%
(d) More than 0.7%
9. Stone like fracture are found in steel due to the formation of
(a) Aluminum oxide at higher temperature
(b) Iron nitride at higher temperature
(c) Iron carbide at higher temperature
(d) Silicon carbide at lower temperature
10. In Stainless steel
(a) Boron and Silicon are the principal alloying element
(b) Sulphur and Phosphorous are the principal alloying element
(c) Lead and Zinc are the principal alloying element
(d) Chromium and Nickel are the principal alloying element
11. Match the following types of irons in Column I and properties in Column II.
Column I
Column II
(A) Grey cast iron
(i) Carbon in combined form as cementite
(B) White cast iron
(ii) Carbon in temper form
(C) Malleable iron
(iii)Carbon in flaky graphite form
(D) Ductile iron
(iv) Graphite in the form of compact nodules all spheroids
(a)
(b)
(c)
(d)
A-iii, B-ii, C-i, D-iv
A-ii, B-iv, C-iii, D-i
A-iii, B-i, C-ii, D-iv
A-ii, B-i, C-iv, D-iii
12. Which of the following statements are true with regard to graphitization?
(i) Both C and SI promote graphitization
(ii) Increasing the cooling rate promote graphitization
(iii)Carbide in white CI can be graphitised slowly in solid state using malleablizing heat
treatment
(a)
(b)
(c)
(d)
only ii
only iii
i & ii
i & iii
13. Which of the following statements are true with regard to the effect of inoculation treatment
of CI?
(i) Controls graphite structure
(ii) Improves mechanical properties
(iii)Anneals the structure
(a) only i
(b) i & ii
(c) ii & iii
(d) i & iii
14. Which of the following statement is true regarding ductile iron?
(i) Ductile iron is produced by Magnesium/Copper treatment of cast iron melt
(ii) High sulphur content is desirable before magnesium treatment to have more graphite
nodule count in ductile iron
(a) a is true but b is false
(b) b is true but a is false
(c) both are true
(d) both are false
15. Which of the following statements are correct related to malleable iron?
(i) Malleable iron can be produced by addition of magnesium Copper in molten white cast
iron
(ii) Malleable iron is obtained by annealing treatment of white cast iron
(iii)White cast iron is not necessary required to obtain malleable iron
(a)
(b)
(c)
(d)
Only i
Only ii
Only iii
All i, ii and iii