Cobalt in steel __________________?

Related Mcqs:

1. Alnico, an alloy used extensively for permanent magnets contains iron, nickel, aluminium and cobalt in the following ratio _____________________?

   A. 50 : 20 : 20 : 10
   B. 40 : 30 : 20 : 10
   C. 50 : 20 : 10 : 20
   D. 30 : 20 : 30 : 20
   E. 50 : 10 : 20 : 20

2. Steel contains____________________?

   A. 80% or more iron
   B. 50% or more iron
   C. alloying elements like chromium, tungsten nickel and copper
   D. elements like phosphorus, sulphur and silicon in varying quantities
   E. high quantities of sulphur

3. Depth of hardness of steel is increased by addition of_________________?

   A. nickel
   B. chromium
   C. tungsten
   D. vanadium
   E. ell of the above

4. Corrosion resistance of steel is increased by addition of________________?

   A. chromium and nickel
   B. sulphur, phosphorus, lead
   C. vanadium, aluminium
   D. tungsten, molybdenum, vanadium, chromium
   E. zinc

5. A reversible change in the atomic structure of the steel with a corresponding change in the properties is known as_________________?

   A. allotropic change
   B. recrystallisation
   C. heat treatment
   D. precipitation
   E. austempering

6. Tungsten in high speed steel provides________________?

   A. hot hardness
   B. toughness
   C. wear resistance
   D. sharp cutting edge
   E. cold hardness

7. Tensile strength of steel can be safely in-creased by________________?

   A. adding carbon up to 2.8%
   B. adding carbon up to 6.3%
   C. adding carbon up to 0.83%
   D. adding small quantities of copper
   E. adding copper and carbon

8. The machinability of steel is increased by___________________?

   A. silicon and sulphur
   B. phosphorous, lead and sulphur
   C. sulphur, graphite and aluminium
   D. phosphorous and aluminium
   E. none of the above

9. The percentage of carbon in low carbon steel is__________________?

   A. 0.05%
   B. 0.15%
   C. 0.3%
   D. 0.5%
   E. 0.7%.

10. The hardness of steel primarily depends on _____________________?

    A. %age of carbon
    B. %age of alloying elements
    C. heat treatment employed
    D. method of manufacture
    E. shape of carbides and their distribution in iron