Solution of Assignment 8

Solution of Assignment 8 1. Using dye penetrant testing method, the type of defects that can be observed is (a) Internal voids (b) Surface cracks (c) ...

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Solution of Assignment 8

1. Using dye penetrant testing method, the type of defects that can be observed is (a) Internal voids (b) Surface cracks (c) Shrinkage inside the casting (d) All of the above 2. Resin impregnation means (a) Filling porous area of casting with a resin (b) Filling pinholes and blowholes with plastic fillers (c) Resin pasted on the surface of casting (d) Spraying resin on casting surface 3. Decrease in hardness and strength after a certain time of ageing treatment is known as (a) Natural ageing (b) Overaging (c) Homogenizing (d) Soaking 4. Magnetic particle test is carried out to reveal the location of (a) Cracks that extend to surface of iron castings (b) Cracks that extend to surface of Aluminium castings (c) Internal voids in Iron castings (d) Internal voids in Aluminium castings 5. Pickling treatment means cleaning the casting with (a) Dilute acid (b) Soda ash (c) Iron shots (d) Compressed air and sand particles 6. During the annealing treatment of casting, cooling is done in (a) Salt bath (b) Brine solution (c) Air (d) Furnace 7. Misrun is a casting defect which occurs due to (a) Very high pouring temperature of the metal (b) Insufficient fluidity of the molten metal (c) Absorption of gases by the liquid metal (d) Improper alignment to the mould flasks

8. Two stream of liquid metal which are not hot enough to fuse properly result into a casting defect known as (a) Cold shut (b) Swell (c) Sand wash (d) Scab 9. The hot tearing in a metal casting is due to (a) High fluidity (b) Coarse sand grain size (c) Poor collapsibility of mold (d) Inadequate riser size 10. Which of the following treatment does not improve hardness? (a) Quenching (b) Cyaniding (c) Normalising (d) Annealing 11. Match the following heat treatment methods of Column I with appropriate working conditions given in Column II. Column I Column II (A) Normalizing (i) Heating components to a temperature range 150-500oc for (B) Full annealing suitable period (C) Hardening (ii) Heating casting to austenitic temperature, holding and then (D) Tempering quenching rapidly (iii)Heating casting to austenitic range, holding and then cooling in furnace (iv) Heating casting to austenitic range, holding and cooling in air (a) (b) (c) (d)

A-ii, B-iii, C-i, D-iv A-iv, B-ii, C-iii, D-i A-iii, B-i, C-ii, D-iv A-iv, B-iii, C-ii, D-i

12. Which of the following statements are true regarding heat treatment of non-ferrous alloys? (i) Homogenization of composition occurs through action of diffusion of atoms (ii) Homogenization of composition is done at room temperature (iii)Larger is the time of ageing and higher the temperature, more will be hardness in case of ageing treatment (iv) During ageing, solute atoms are rejected and form cluster of coherent/semi-coherent precipitate (a) i and iii (b) ii and iv

(c) ii and iii (d) i and iv 13. The correct reasons for the occurrence of hot tear in casting among the following reasons will be (i) Hindered contraction occurring immediately after metal has solidified (ii) Poor collapsibility of mould and core (iii)Too high pouring temperature (a) (b) (c) (d)

i and ii only i and iii only ii and iii only i, ii and iii

14. Facts regarding heat treatment of cast iron are, (i) Prolonged annealing decomposes the graphite carbon in white cast iron (ii) The machinability of grey iron decreases by annealing treatment (iii)Cementite decomposes to graphite during annealing treatment of white cast iron (a) (b) (c) (d)

Only i and ii Only ii and iii Only iii None of these

15. Which of the following defects are likely to be caused because of improper ramming of moulding material? (i) Cold shut (ii) Misrun (iii)Swell (iv) Drop (v) Metal penetration (vi) Shift (a) (b) (c) (d)

i, iii and vi only ii, iv and vi only iii, iv and v only ii, v and vi only