Magnetic particle testing can detect both production discontinuities, such as seams, laps, grinding cracks and quenching cracks, and inservice damage, such as fatigue and overload cracks.
Next to visual testing, it is one of the most cost effective methods of nondestructive testing. Its major difficulty is that the test object must be magnetizable. Magnetic particle technology depends on the property of magnetism occurring in certain elements referred to as ferromagnetic materials.Magnetic particle testing is a relatively simple test method that can be applied to finished articles, billets, hot rolled bars, castings and forgings. It can also be used to confirm that the processing operations, such as heat treatment, machining and grinding, did not cause discontinuities. There are many differing modes of electrical current that are used in magnetic particle testing.
Magnetic particle testing consists of magnetization of the test object, followed by the application of the particles and interpretation of the patterns formed by the particles as they are attracted by magnetic leakage fields. These patterns of magnetic particles are compared to codes or known standards to determine test object acceptability.
The purpose of this classroom training book is to provide the fundamental knowledge of magnetic particle testing required by quality assurance and nondestructive testing personnel. This knowledge will enable them to ascertain that the proper test technique is used to ensure the quality of the finished product, to interpret, evaluate and make a sound decision as to the results of the test and to recognize those areas exhibiting doubtful test results that require either retesting or assistance in interpretation and evaluation.