This set of Testing of Materials online quiz focuses on “Liquid Penetrant & Magnetic Particle Inspection”.
1. What is the disadvantage of LPI?
c) Not reliable
d) Depth restriction
Explanation: LPI is a fast, non-expensive and reliable test. It is limited by the depth of defect. So disadvantage of LPI is Depth restriction.
2. LPI can’t be used on __________ specimen.
d) Internally defected
Explanation: Penetrant is applied on the surface so surface defects only can be detected. LPI can be applied on large, small, simple or complex shapes.
3. Which order is right for LPI?
a) Penetrant apply, development, inspection, surface preparation
b) Surface preparation, penetrant apply, development, inspection
c) Penetrant apply, development, surface preparation, inspection
d) Development, surface preparation, penetrant apply, inspection
Explanation: Firstly surface is cleaned. Penetrant is applied and surface flow is made visible. Finally, surface is inspected.
4. What is general dwell time?
a) 20 seconds
b) 2 minutes
c) 20 minutes
d) 2 hours
Explanation: Generally dwell time is kept 20 to 30 minutes. It can be increased depending on size.
5. __________ increases the visibility of the flaw in LPI.
Explanation: Function of a developer is to make flaw visible. It provides the required contrast.
6. Developer is chosen such as benzene.
Explanation: Developer is usually a fine chalk or talc powder. It is applied on the surface by dusting or by spraying.
7. Small components are dipped in penetrant.
Explanation: Dwell time vary with component size. Small components are dipped into a liquid penetrant bath.
8. Which materials can be tested by MPI?
Explanation: MPI works only on materials which can be magnetized easily. These are ferromagnetic materials.
9. Which material can’t be tested by MPI?
Explanation: Mg is non-ferromagnetic material. So it can’t be tested by MPI. Co, Fe and Ni are ferromagnetic.
10. What is Curie point for most of the ferrous magnetic materials?
Explanation: The Curie point for most of ferrous magnetic materials is760˚C. Above it, these don’t show ferromagnetism.
11. The minimum width of crack, which can be inspected by MPI, is _________
Explanation: A surface crack of width as fine as 1µm can be detected. Subsurface flaws can also be inspected using this method.
12. What is the advantage of using DC in MPI?
a) Battery maintenance
b) Demagnetize easy
c) Variable voltage supply
d) Subsurface detection
Explanation: Subsurface flaws can also be detected by using DC supply. But demagnetization becomes difficult.
13. Benzene and alcohol are used to decrease component.
Explanation: The surface of the component must be cleaned before MPI. Benzene and alcohol are used to decrease.
14. Plain carbon steels are applied with magnetic particles by a residual method?
Explanation: Plain carbon steels are soft magnetic materials. The method of applying magnetic particles is continuous.
Sanfoundry Global Education & Learning Series – Mechanical Behaviour & Testing of Materials.
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