L1&2 General

Question 1

MPI is most likely to find subsurface discontinuities in what kind of steels?

Answer 1

Soft steels with high permeability

Question 2

Cracks caused by alternating stresses above a critical level are called what?

Answer 2

Fatigue cracks

Question 3

What is the magnetic flux density in the centre of a bar magnetized with a headshot?

Answer 3

Zero

Question 4

Describe the magnetic flux density on the inside surface of a ferromagnetic tube magnetized with a central conductor?

Answer 4

Magnetic flux will be the highest

Question 5

The prod method would be most sensitive to cracks where?

Answer 5

Parallel to a line connecting the prod contact points

Question 6

What is the common rule of thumb to use for current required in circular magnetization?

Answer 6

1000 ampere turns per 25 mm diameter

Question 7

For direct contact magnetizing methods, current should be flowing in what direction relative to expected discontinuities?

Answer 7

Parallel

Question 8

The magnetic field outside a conductor decreases…

Answer 8

In a linear manner

Question 9

How is the magnetic field strength at the surface of a magnetic conductor compared to a non magnetic conductor?

Answer 9

The same

Question 10

What PARTICLES are the most sensitive?

Answer 10

Dry particles

Question 11

A advantage to this method is that it has superior sensitivity to subsurface cracks.

Answer 11

Dry method

Question 12

A disadvantage to this method is that it doesn’t have excellent detection of completely subsurface cracks…

Answer 12

Wet method

Question 13

An advantage of this method is its ease of bath recovery and reuse..

Answer 13

Wet method

Question 14

Describe fluorescent dyes:

Answer 14

Dyes that receive light at one wavelength and re-emit light of another wavelength

Question 15

What’s the most common way to demag small test pieces?

Answer 15

Pass it through an AC coil

Question 16

How can you remove MPI indications that are due to cold work?

Answer 16

Heat treating

Question 17

What will a continuous linear indication along the centre of a fillet weld most likely to be?

Answer 17

A root indication

Question 18

A minimum of how many mag operations is required when orientation of likely indication is unknown?

Answer 18

Minimum of 2

Question 19

What type of indications are produced when flux lines are parallel to a discontinuity?

Answer 19

None

Question 20

A split coil would mostly likely be used with…

Answer 20

A portable mag unit

Question 21

What is the most common harmful effect of exposure to black lights?

Answer 21

Eyeball fluorescence

Question 22

What magnetic field may be present without any external evidence?

Answer 22

Circular

Question 23

What are irregularly shaped, checked and scattered marks usually caused by local friction overheating?

Answer 23

Grinding cracks

Question 24

What is it called when you assess whether a discontinuity will have a detrimental effect on the part?

Answer 24

Evaluation

Question 25

What is it called when you’re measuring and recording discontinuities?

Answer 25

Reporting

Question 26

What is it called when you’re judging from an indication what the cause and nature are?

Answer 26

Interpretation

Question 27

Surrounding an electromagnet, just prior to reversal, the magnetic field is the...

Answer 27

Strongest

Question 28

Where are the lines of flux/magnetic force contained in a circularly magnetized ferromagnetic bar?

Answer 28

Within and around the part

Question 29

What are 3 advantages of AC?

Answer 29

1. Most readily available 2. Equipment can be made lighter 3. Leaves part demagnetized

Question 30

What current would be best to detect fatigue cracks?

Answer 30

AC

Question 31

On a small forging, indications appear as some sharp and some broad & fuzzy, what are these most likely to be?

Answer 31

Magnetic writing

Question 32

Piping is what type of discontinuity?

Answer 32

Inherent

Question 33

What is the common rule of thumb for circular magnetization?

Answer 33

1000 amps/25 mm of diameter

Question 34

What is the best method to use on a large casting?

Answer 34

DC

Question 35

What is the ideal black light wavelength?

Answer 35

365 nm

Question 36

What is the max white light intensity in darkened conditions?

Answer 36

21.5 lux (2 ft. candles)

Question 37

What is the white light intensity for inspecting with black and white contrast paint?

Answer 37

1074 lux or 100 ft. candles

Question 38

What is are the properties of a diamagnetic material?

Answer 38

Very weak negative attraction

Question 39

What is the advantage of half way direct current over straight DC?

Answer 39

It improves particle mobility

Question 40

Why is the wet method better for fine defects?

Answer 40

More particle mobility

Question 41

Localized poles caused by a break have 2 names:

Answer 41

1. Concurrent | 2. Consequent

Question 42

More permeable allows particles to what?

Answer 42

Become more dense

Question 43

What is the wavelength of the electromagnetic spectrum?

Answer 43

400-700 nm