2014-Sustainable Industrial Processing Summit
SIPS 2014 Volume 7: Energy Production, Environmental & Multiscale
| Editors: | Kongoli F |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2014 |
| Pages: | 528 pages |
| ISBN: | 978-1-987820-09-6 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Non-destructive Testing (NDT) in Ferromagnetic Materials
Maryam Dehghani1;1NATIONAL IRANIAN OIL COMPANY, Omiodieh, Iran (Islamic Republic of Iran);
Type of Paper: Regular
Id Paper: 154
Topic: 15
Abstract:
Non-destructive testing can perform measurements or tests on materials without damaging or altering those materials. There are several types of non-destructive testing methods, including Magnetic Particle Inspection (MT), which is one of the best-known and commonly used methods of NDT. Its aim is to detect the presence of surface braking discontinuities (cracks) in the part under inspection. Only Ferromagnetic materials can be inspected by the MT method. This is because Ferromagnetic materials develop strong internal magnetic fields when an electrical current is passed through them. An electric current can be introduced in the test part in several ways. It can be wrapped in encircling coils and rods or the current can be applied directly with the use of the yoke, producing a magnetic field perpendicular to the current flow. When these internal magnetic fields encounter a change in permeability, the magnetic field is forced outside of the materials surface, and produces flux leakage. This leakage will attract any other Ferromagnetic materials that may be close to the leakage site.
For this operation, depending on the face of the material or part under test magnetized, discontinuities that lie in a direction generally transverse to the direction of the magnetic field will cause a leakage field, and therefore, the presence of the discontinuity is detected by the use of finely divided ferromagnetic particles applied over the surface. Some of these particles, being gathered and held by the leakage field, this magnetically held collection of particles form an outline of the discontinuity and indicate its location, size, shape and extent. In this paper, we discuss this method.