·Table of Contents ·Methods and Instrumentation | The Non-destructive Evaluation Method for Far-side Corrosive Type Flaws in Steel Plates Using Magnetic Flux Leakage TechniqueKazuyoshi SekineFaculty of Engineering, Yokohama National University Tokiwadai 79-5, Hodogayaku, Yokohama, JAPAN Naoya Kasai Graduate Student of Yokohama National University; Tokiwadai 79-5, Hodogayaku, Yokohama, JAPAN Hiroaki Maruyama Japan National Oil Corporation; Uchisaiwaicho 2-2-2, Chiyodaku, Tokyo, JAPAN Contact |
Fig 1: Sketch of experimental set-up for the far-side MFL inspection |
Fig 2: Magnetic flux density distribution from circular holes of a 8mm depth (horizontal component) | Fig 3: Magnetic flux density distribution from rectangulare grooves of 50mm width(horizontal component) |
Fig 4: Magnetic flux density distribution from circular holes of 8mm depth (vertical component) | Fig 5: Magnetic flux dcnsity distribution from rectangular grooves of 50mm with(vertical component) |
Fig 6: Relationship between the real flaw width and the | Fig 7: Relationship between the real flaw depth and |
Fig 8: Relationship between the two dimensional flaw section-area and DBy and DBy | Fig 9: Two dimensional far-side flaw model |
(1) |
(2) |
where the equivalent current moment I_{2}=(m-1)(d+g)/(m(d+g)+(1-m)d)×H_{0}gd (H_{0 }: applied magnetic field, : permeability) and the mirror image factor due to the presence of boundary between the and the is m_{2}=2+g^{2}/6h(h+d) . The other geometrical parameters in the above equations are denoted in Fig.9.
Fig 10: Magnetic flux leakage distribution from the flaw of a 8mm depth (vertical component ,equivalent current model) |
Fig 11: Magnetic flux leakage distribution from the flaw of a 50mm width
(vertical component ,equivalent current model) |
Fig 12:Reationship Between the flaw depth and corrected DBy (theoretical) |
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