1. Nickel addition in alloys
a) Increases toughnes
b) Increases hardenability and impact resistance
c) Limit grain growth during heat treatment process
d) All of the mentioned
Explanation: Nickel addition increases toughness by limiting grain growth
2. Flame hardening involves.
a) Heating the surface above the transwerformation range
b) Quenching after heating
c) Minimum case depth is 1mm
d) All of the mentioned
Explanation: Flame Hardening is a process of heating the surface with a flame above critical temperature and then quenching it.
3. Induction hardening process involves
a) Heating surface by induction in field of invariable current
b) Case depth minimum of 2mm are produced
c) Heating surface by induction in field of alternating current
d) None of the mentioned
Explanation: Heating can only be done in presence of alternating current and not constant current.
4. Case carburising involves
a) Introducing carbon at surface layer
b) Heating range 880 to 980’C
c) Case depths up to 2mm are possible
d) All of the mentioned
Explanation: Case carburising involves introducing carbon at surface layer. Medium can be liquid, solid or gas and high case depths are possible.
5. Which of the following are not true for carbo nitriding?
a) Introducing carbon and nitrogen at surface layer
b) Component is heated in range of 650 to 920’C
c) Cyaniding is similar to carbo nitriding except that the medium is liquid
d) This process gives a lower wear resistance compared to case carburising process
Explanation: Carbo nitriding gives wear resistance greater than compared to case carburising
6. Which of the following are true for nitriding?
a) Nascent oxygen is involved
b) Temperature range 490 to 590’C
c) Gaseous or liquid medium
d) All of the mentioned
Explanation: In nitriding nascent oxygen is acted on the surface of the product at a temperature of 490 to 590’C in a gaseous or liquid medium.
7. Stressed parts are always kept in tension.
a) True
b) False
Explanation: Cast iron has more compressive strength.
8. Shot blasting process improves the endurance limit of the component
a) True
b) False
Explanation: Shot blasting employs throwing wheel which imparts strength to the material.
9. Which process allows controlling grain structure of the product?
a) Casting
b) Forging
c) None of the mentioned
d) Die Casting
Explanation: In casting metal is in fluid state and hence impossible to control the grain structure.
10. While designing a forging, the profile is selected such that the fibrous lines are parallel to the tensile forces and perpendicular to shear forces.
a) True
b) False
Explanation: Tensile load is applied parallel to the grain structures.