Liquid Penetrant Test
This is a method which can be employed for the detection of open to surface discontininuties in any induindual product which is made from a non-porous material.In this method a liquid penetrant is applied to the surface of the product for a certain predetermined time,after which excess penetrant is removed from the surface.The surface is then dried and a developer is applied to it.The penetrant which remains in the discontinuity is absorbed by the developer to indicate the presence as well as the location,size and nature of the discontinuity.
Four stages of liquid penetrant process
a. Penetrant application and seepage into the discontinuity
b. Removal of excess penetrant
c. Application of developer
d. Inspection for the presence of discontinuities
Magnetic particle test
Magnetic particle testing is used for the testing of materials which can be easily magnetised.This method is capable of detecting open to surface and just below surface flaws.In this method the test specimen is first magnetised either by using a permanent magnet or an electric cuurent through or around the specimen.The magnetic field thus introduced into the specimen is composed of magnetic lines of force.Whenever there is a flaw which interrupts the flow of magnetic lines of force,some of these lines must exit and re-enter the specimen.These points of exits and re-entry from opposite magnetic poles and whenever minute magnetic particles are sprinkled onto the surface of the specimen, these particles are attracted by these magnetic poles to create a visual indication approximating the size and shape of the flaw.
This is a method which can be employed for the detection of open to surface discontininuties in any induindual product which is made from a non-porous material.In this method a liquid penetrant is applied to the surface of the product for a certain predetermined time,after which excess penetrant is removed from the surface.The surface is then dried and a developer is applied to it.The penetrant which remains in the discontinuity is absorbed by the developer to indicate the presence as well as the location,size and nature of the discontinuity.
Four stages of liquid penetrant process
a. Penetrant application and seepage into the discontinuity
b. Removal of excess penetrant
c. Application of developer
d. Inspection for the presence of discontinuities
Magnetic particle test
Magnetic particle testing is used for the testing of materials which can be easily magnetised.This method is capable of detecting open to surface and just below surface flaws.In this method the test specimen is first magnetised either by using a permanent magnet or an electric cuurent through or around the specimen.The magnetic field thus introduced into the specimen is composed of magnetic lines of force.Whenever there is a flaw which interrupts the flow of magnetic lines of force,some of these lines must exit and re-enter the specimen.These points of exits and re-entry from opposite magnetic poles and whenever minute magnetic particles are sprinkled onto the surface of the specimen, these particles are attracted by these magnetic poles to create a visual indication approximating the size and shape of the flaw.
a). The effect of defects on the flux flow in a cylindrical specimen
b). The effect of defects on the flux flow ina magnetized ring
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