Brass parts with high residual tensile stress at the surface are susceptible to season cracking (i.e. spontaneous cracking occuring on exposure to atmospheric corrosion), if its zinc percentage is more than ?

Related Mcqs:

1. A form of stress corrosion failure termed as ‘season cracking’ is generally observed in __________________?

   A. Thermosetting polymers
   B. High carbon steels
   C. Brasses
   D. Borosilicate glasses

2. Steam condenser tubes are made of admiralty brass, in which percentage of zinc & copper are _______________ respectively ?

   A. 70 & 30
   B. 30 & 70
   C. 50 & 50
   D. 90 & 10

3. In case of brasses, with decreasing zinc percentage and increasing copper percentage, its _____________ increases ?

   A. Percentage elongation
   B. Brinell hardness
   C. Tensile strength
   D. All A, B & C

4. A cylindrical rod subjected to a tensile strain within the elastic limit undergoes a volume change. If the volume strain is equal to half the tensile strain, then the Poisson’s ratio of the rod is___________________?

   A. 0
   B. 0.33
   C. 0.44
   D. 0.25

5. In “Imperial Smelting Process” for extraction of zinc, zinc vapour thus produced is quenched in the external condenser by the use of the following _______________________?

   A. Jet of water at high pressure
   B. Blast of air
   C. Mixture of water and air
   D. Rain of molten lead

6. According to maximum shear stress failure criterion, yielding in material occurs, when the maximum shear stress is equal to _______________ times the yield stress ?

   A. 0.5
   B. 2
   C. √2
   D. √3/2

7. Probability of cavitation occuring becomes very high, when the local _______________ resulting ?

   in water bubbles formation, which on rupture cause cavitation
   A. Pressure falls below the vapour pressure
   B. Pressure becomes very high
   C. Temperature becomes low
   D. All A, B & C

8. Cold cracking in the heat affected zone of a high strength steel weld can take place because of the___________________?

   A. Retained austenite
   B. Martensite formation
   C. Relatively high sulphur content in the base metal
   D. Sufficient hydrogen present in the welding arc

9. _____________ is the process of coating the surface of steel with aluminium oxide, thereby imparting it increased resistance to corrosion & oxidation upto a temperature of 700°C ?

   A. Veneering
   B. Galvanising
   C. Electroplating
   D. Calorising

10. Which of the following is the most suitable abrasive for grinding high tensile strength materials ?

    A. Silicon carbide
    B. Corundum
    C. Aluminium oxide
    D. Boron carbide