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20 TOP MECHANICAL ENGINEERING JOB INTERVIEW QUESTIONS ON ENGINEERING MATERIALS



 1.Metals are classified into:

 Ans: Metals are cl TVassified into TWO Types
 (a)  Ferrous metals; sand
 (b) Non-ferrous metals


 2. What are Ferrous metals?

 Ans:The ferrous metals are those which have the iron as their main constituent, such  as cast iron ,wrought iron and steel.




3.What are Non-Ferrous Metals?

 Ans:The non ferrous metals are those which have a metals other than iron as their main  constituent,such as copper,aluminium,brass,tin,zinc etc.





3.What is  STRENGTH ?

 Ans: It is the ability of  a material to resist the externally applied forces without breaking or yielding.


 4. What is STIFFNESS ?

 Ans:   It is the ability of  a material to resist deformation under stress.The modulus of  elasticity is the measure of stiffness.


5.What is  ELASTICITY ?

Ans:  It is the property of a material  to regain its original shape after deformation when the external forces are removed.This property is desirable for materials used in tools and machines.It may be noted that steel is more elastic than rubber.


6.What is  PLASTICITY ?

 Ans: It is the property of material which retains the deformation produced under load permanently.This property of material is necessary for forgings stamping images on coins,and in ornamental work.


7. What is  DUCTILITY ?

Ans:  It is property of material enabling it to drawn into wire with the application of a tensile force.A ductile material commonly used in engineering practice (in the order of diminishing ductility)are mild steel,copper,aluminium,nickel,zinc,tin and lead.


8.  What is  BRITTLENESS ?

Ans: It is the property of material opposite to ductility.It is the property of breaking of a material with the little permanent distortion.Cast iron is a brittle material.


9. What is MALLEABILITY ?

Ans: It is a special case of ductility which permits materials to be rolled or hammered into thin sheets.A malleable material should be plastic but it is not essential to be so strong.The malleable materials commonly used in engineering practice(in order of diminishing malleability)are lead,soft steel,wrought iron,copper and aluminium.



10. . What is TOUGHNESS ?

Ans: It is the property of material to resist fracture due to high impact loads like hammer blows.The toughness of a material decreases when it is heated.This property is desirable in parts subjected to shock and impact loads.


11. . What is  RESILIENCE ?

Ans:  It is the property of material to absorb energy and to resist shock and impact loads.It is measured by amount of energy absorbed per unit volume within elastic limit.This property is essential for spring materials.


12.. What is  CREEP ?

Ans:  When a part is subjected to a constant stresses at high temperature for a long period of time,it will undergo a slow and permanent deformation called"creep".This  property is considered in designing internal combustion engines,boilers and turbines.


13. What is  FATIGUE ?

Ans:  When a material is subjected to repeated stresses, it fails at stresses below the yield point stresses.Such types of failure of a material is known as "fatigue".The failure is caused by means of progressive crack formation which are usually fine and microscopic size.This property is considered in designing shafts, connecting rods, springs, gears etc.


14.. What is HARDNESS ?

Ans: It is a very important property of the metals and has a wide variety of meanings.It embraces many different properties such as resistance to wear, scratching, and machinability etc.It is also mean t he ability of a metal to cut another metal.The hardness is usually expressed in numbers which are dependent upon the method of making test.


 

15. What is pig Iron?

Ans: It is the crude form of iron and is used as a raw material for the production of various other ferrous metals, such as cast iron,wrought iron and steel.The pig iron is obtained by smelting iron ores in a blast furnace.


16.What is Cast iron?

Ans: The Cast iron is obtained by remelting pig iron with coke and lime stone in a furnace known as cupola.It is primarily an alloy of iron and carbon. The carbon contents in cast iron varies from 1.7 to 4.5%. It may be present either as free carbon(or graphite) or combined carbon(or cementite).


17. What is Wrought Iron?

Ans: It is the purest iron which contains 99.5% iron but  a very low carbon (less than 0.08%) content in contrast to cast iron (2.1% to 4%). It can not stand sudden and excessive shocks. It can be easily forged or welded.


18. What is steel?

Ans: It is an alloy of iron and carbon, with carbon content up to a maximum of 1.5%.Most of the steel produced now-a-days is plan carbon steel or simply carbon steel.


19.What is Alloy steel?

Ans: An alloy steel may be defined as a steel to which elements other than carbon are added in sufficient amount to produce an improvement in properties.


20.What is Stainless Steel?

Ans: It is defined as that steel which when correctly heat treated and finished, resists oxidation and corrosive attack from most corrosive media.





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