Damage to metal surface by mechanical action is called____________________?

Related Mcqs:

1. Solidification time of a molten metal in a casting is proportional to (where, V = volume of metal & A = its surface area; in the casting) ?

   A. V/A
   B. V/A2
   C. V2/A
   D. V2/A2

2. Oxide layer formed on the non-ferrous metal surface after its annealing is__________________?

   A. Removed by acid pickling
   B. Hammered into the surface
   C. Removed with coarse emery cloth
   D. Left as such to protect the surface

3. ____________ is the process used for setting up compressive stresses in the surface of a metal to improve its fatigue strength ?

   A. Lancing
   B. Shot peening
   C. Slugging
   D. Spinning

4. For infinite parallel planes having emissivities ε1 & ε2, the interchange factor for radiation from surface 1 to surface 2 is given by__________________?

   A. (ε1 + ε2)/ε1.ε2
   B. ε1.ε2/(ε1 + ε2 – ε1.ε2)
   C. ε1.ε2
   D. ε1 + ε2

5. Insulation of liquid surface can be achieved by _____________ on top of its surface?

   A. Floating hollow polypropylene spheres
   B. Spraying alumina powder
   C. Putting cement
   D. None of these

6. For separating small pieces of metal from engine oil of a car, the best separating technique is the _____________________ ?

   A. Chromatography
   B. Evaporation
   C. Filtration
   D. Fractional distillation

7. Hot dipping process is used for coating a low melting point metal (e.g. Pb, Sn, Zn) on iron, steel & copper having relatively higher melting points. Which of the following is not a hot dipping process ?

   A. Galvanising
   B. Tinning
   C. Sherardizing
   D. None of these

8. Earing is a defect found in steels after the following metal working operation ?

   A. Extrusion
   B. Rolling
   C. Deep drawing
   D. Wire drawing

9. What is the critical radius of insulation (cms) for a metallic cylinder, if the convective heat transfer co-efficient with the ambient atmosphere is 5 W/m2. °K? Thermal conductivity of metal and insulation material are 40 and 0.1 W/m.°K respectively ?

   A. 2
   B. 8
   C. 10
   D. 40

10. Specific gravity of hot metal (pig iron) is ______________ times that of the blast furnace slag ?

    A. 2
    B. 3
    C. 0.8
    D. 6