magnetic particle

Question 1

alternating current

Answer 1

electric current periodically reversing in direction

Question 2

continuous method

Answer 2

the magnetic particle inspection method in which particles in either wet or dry form are applied to the surface of the part at the same time the part is being magnetized

Question 3

fatigue cracks

Answer 3

progressive cracks that develop in the surface caused by the repeated loading and unloading of the part

Question 4

defect

Answer 4

a fault in any material or part detrimental to its serviceability. all cracks, seams, laps, etc are not necessary defects as they may not affect the serviceability of the part in which they exist.

Question 5

direct current

Answer 5

an electric current that flows in one direction

Question 6

discontinuity

Answer 6

as used in connection with magnetic particle inspection, anything that causes an interruption in the magnetic path. a crack, slag inclusion, gas pocket, etc

Question 7

evaluation

Answer 7

the determination of the significance of discontinuities from the standpoint of whether they are detrimental defects or inconsequential blemishes.

Question 8

fatigue

Answer 8

the phenomenon of the progressive fracture of a metal by means of a crack, which spreads under repeated cycles of stress.

Question 9

ferromagnetic

Answer 9

materials that are strongly attracted by a magnetic field.

Question 10

circular field

Answer 10

a magnetic field which surrounds a nonmagnetic conductor of electricity or which exists and is completely contained within and also surrounds a magnetic conductor of uniform cross-section. generally applied to the magnetic field within and surrounding any magnetic conductor or part resulting from a current passed through it from one end to the other.

Question 11

longitudinal field

Answer 11

a field which extends within a part from one or more poles to another or other poles and which is completely through a path external to the part

Question 12

residual field

Answer 12

the field that remains in a piece of magnetizable material after the magnetizing force has been removed

Question 13

fluorescence

Answer 13

the property of certain materials of emitting visible light during their subjection to black light

Question 14

inclusions

Answer 14

impurity particles, usually oxides, sulfides or silicates. generally dispersed at random through the metal

Question 15

interpretation

Answer 15

the determination of the cause of a magnetic particle indication

Question 16

laminations

Answer 16

discontinuities in a plate sheet or strip caused by pipe, inclusions, or blowholes from the original ingot usually flat and parallel to the outside surface

Question 17

lines of force

Answer 17

imaginary lines used to visualized the direction of the force in an external magnetic field. see flux lines

Question 18

magnetic particle inspection

Answer 18

a nondestructive inspection method for locating discontinuities in ferromagnetic materials through the location of leakage magnetic fields by their attraction for finely divided, ferromagnetic particles.

Question 19

magnetic writing

Answer 19

a form of non-relative indication some times caused when the surface of a magnetized part comes in contact with another piece of ferromagnetic material

Question 20

non-relevant indication

Answer 20

a magnetic particle indication due to a leakage magnetic field which is not caused by an actual discontinuity in the magnetized material, but by some other condition which does not affect the usefulness of the part.

Question 21

permeability

Answer 21

the ability of material to become magnetized. it is the relation between the field strength and the magnetizing force

Question 22

reluctance

Answer 22

the degree of difficulty with which the magnetic flux is produced. materials of high permeability have low reluctance.

Question 23

retentivity

Answer 23

the ability of a material to retain a portion of the magnetic field set up in it after the magnetizing force has been removed.

Question 24

saturation

Answer 24

the point in the magnetization of magnetizable object at which an increase in the magnetizing force produces no increase in the magnetic field within the part

Question 25

suspension

Answer 25

the correct term applied to the light oil bath in which, is suspended the ferromagnetic particles used in the wet method.