Question Set 95

1.What is the maximum use of magnesium ?

Ans: Magnesium is used to alloy with aluminium and as an additive for making SG (Spheroidal Graphite) iron.

2.What for zinc finds applications ?

Ans: Galvanizing consumes the largest proportion of zinc. Zinc is resistant to corrosion but is attacked by acids and alkalies. Zinc alloy.s are suited for making die casting since the melting point is reasonably low.

3.Which factors influence the type of fracture in failure of a material ?

Ans: Seven factors influencing type of failure are :

(i) Type of material (inherent structure properties),

(ii) Manner of loading (Static versus dynamic),

(iii) Range of imposed stress,

(iv) Strain rate (static, dynamic, impact),

(v) Stress distribution (discontinuity in material/shape),

(vi) temperature, and

(vii) surface treatment.

4.What is the name given to ratio of actual cycle efficiency and ideal cycle efficiency.

Ans: Efficiency ratio.

5.List two effects of manganese in plain carbon steels. ,

Ans: Manganese increases tensile strength and hardness. It decreases weldability.

6.Name the strongest and weakest type of atomic bonds.

Ans: Metallic bond is strongest and molecular bond also known as Vander Waals bond is weakest.

7.In which process internal energy remains constant ?

Ans: Isothermal process.

8.What is temper embrittlement in alloy steels and what are its effects ?

Ans: Embrittlement attack is usually intergranular in metals, i.e. cracks progress between the grains of the polycrystalline material. It imparts a tendency to fail under a static load after a given period of time in those alloy steels which are susceptible to embrittlement.

9.What are whiskers ?

Ans: Whiskers are very small crystals which are virtually free from imperfections and dislocations.

10.What is Bauschinger effect ?

Ans: According to Bauschinger, the limit of proportionality of material does not remain constant but varies according to the direction of stress under cyclic stresses.