This set of Metal Casting Multiple Choice Questions & Answers (MCQs) focuses on “Magnaflux Test”.
1. Which of the following defects are not detected by magnetic particle inspection?
a) Surface cracks
b) Quenching cracks
c) Thermal cracks
d) Fatigue cracks
View Answer
Explanation: Quenching cracks, thermal cracks, grinding cracks or fatigue cracks are a few types of defects which can be detected by magnetic particle test, whereas surface cracks are defects which can be detected by simple visual inspection.
2. When an AC current is used for magnaflux test, what is its frequency?
a) 35 cycles/sec
b) 45 cycles/sec
c) 55 cycles/sec
d) 65 cycles/sec
View Answer
Explanation: A magnaflux test is the one which is used for testing and detecting for any kind of thermal defect or any kind of quenching crack. For doing this, an alternating current can be used. The frequency of the alternating current is in the range of 50 to 60 cycles every second.
3. Which of the following materials can be tested using magnetic particle testing?
a) Brass
b) Steel
c) Bronze
d) Solder
View Answer
Explanation: Among the following materials, only ferrous materials can be tested using a magnetic particle test, which is therefore steel. Brass and bronze are copper alloys and solder is an alloy of zinc, lead and tin.
4. Which current is helpful in detecting sub surface discontinuities?
a) High frequency AC
b) Low frequency AC
c) Full wave DC
d) Half wave DC
View Answer
Explanation: None.
5. Which current is helpful in detecting surface breaking indication?
a) High frequency AC
b) Low frequency AC
c) Full wave DC
d) Half wave DC
View Answer
Explanation: None.
6. Magnetic particles with fluorescent coating are seen under which light?
a) White light
b) Infrared light
c) Black light
d) Ultraviolet light
View Answer
Explanation: In magnetic particle testing, only ferrous materials can be tested using a magnetic particle test. The casting which is undergoing magnetic inspection, if it is coated with fluorescence, then it has to be viewed in an ultraviolet light only.
7. What is the skin depth of copper at 60 Hz frequency?
a) 8 mm
b) 8.5 mm
c) 9 mm
d) 9.5 mm
View Answer
Explanation: The distribution of an alternating electric current inside the conductor, and the flow of current through the skin of the material is called skin effect. The depth of the skin effect is skin depth. For copper, at frequency 60 Hz, the skin depth is 8.5mm.
8. What is the size range of dry particle powder?
a) 5 to 170 micrometers
b) 15 to 185 micrometers
c) 45 to 215 micrometers
d) 65 to 250 micrometers
View Answer
Explanation: Dry particle powder is basically applied in the form of a spray or a cloud. This powder is designed to be seen in white light. The particle size of dry particle powder is 5 to 170 micrometers.
9. Half wave DC is more penetrative in magnaflux testing than full wave DC.
a) True
b) False
View Answer
Explanation: For the detection of sub surface defects, a full wave direct current is needed. For the detection of surface breaking indication, a half wave direct current is needed. A half wave direct current is more penetrative than full wave direct current.
10. Magnetic field lines travel from north to south.
a) True
b) False
View Answer
Explanation: Magnetic field lines are imaginary lines, which travel from north pole of the magnet to the south pole of the magnet. These lines do not travel through the specimen but around it.
Sanfoundry Global Education & Learning Series – Metal Casting, Forming and Welding.
To practice all areas of Casting, Forming and Welding, here is complete set of 1000+ Multiple Choice Questions and Answers.
