scholarly journals Magnetic Flux Leakage Course of Inner Defects and Its Detectable Depth

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jianbo Wu ◽  
Wenqiang Wu ◽  
Erlong Li ◽  
Yihua Kang
Keyword(s):  
Magnetic Flux ◽  
Steel Structure ◽  
High Sensitivity ◽  
Magnetic Flux Leakage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Near Surface ◽  
Testing Method ◽  
Non Destructive ◽  
Flux Leakage

AbstractAs a promising non-destructive testing (NDT) method, magnetic flux leakage (MFL) testing has been widely used for steel structure inspection. However, MFL testing still faces a great challenge to detect inner defects. Existing MFL course researches mainly focus on surface-breaking defects while that of inner defects is overlooked. In the paper, MFL course of inner defects is investigated by building magnetic circuit models, performing numerical simulations, and conducting MFL experiments. It is found that the near-surface wall has an enhancing effect on the MFL course due to higher permeability of steel than that of air. Further, a high-sensitivity MFL testing method consisting of Helmholtz coil magnetization and induction coil with a high permeability core is proposed to increase the detectable depth of inner defects. Experimental results show that inner defects with buried depth up to 80.0 mm can be detected, suggesting that the proposed MFL method has the potential to detect deeply-buried defects and has a promising future in the field of NDT.

Magnetic Flux Leakage Method of Railway Rails Defects diagnostics and its Place Among Mobile Means of Non-destructive Testing

2018 ◽  
pp. 105-119
Author(s):  
Nichoha, Vitalij ◽  
Shkliarskyi, Volodymyr ◽  
Storozh, Volodymyr ◽  
Matiieshyn, Yurij ◽  
Vashchyshyn, Liubomyr
Keyword(s):  
Magnetic Flux ◽  
Magnetic Flux Leakage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Non Destructive ◽  
Flux Leakage

scholarly journals Non-Destructive Testing of Steel Corrosion Fluctuation Parameters Based on Spontaneous Magnetic Flux Leakage and Its Relationship with Steel Bar Diameter

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4116 ◽  
Author(s):  
Qingyuan Zhao ◽  
Jianting Zhou ◽  
Qianwen Xia ◽  
Senhua Zhang ◽  
Hong Zhang
Keyword(s):  
Magnetic Flux ◽  
Steel Corrosion ◽  
Magnetic Flux Leakage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Detection Technology ◽  
Steel Bar ◽  
Steel Bars ◽  
Non Destructive ◽  
Flux Leakage

In an actual structure, the arrangement of steel bars is complicated, there are many factors affecting the corrosion of steel bars, and these factors affect each other. However, accurately reflecting the corrosion of steel bars in actual engineering through theoretical calculations is difficult. Besides, it is impossible to detect and evaluate steel bars rust completely and accurately. This article is based on spontaneous magnetic leakage detection technology and adopts the method of stage corrosion and scanning along the reinforcing bar. Based on spontaneous magnetic flux leakage detection technology, the linear change rate of the tangential component curve of the magnetic flux leakage signal generated after the corrosion of a steel bar is studied, and a comparison is made between the steel bar coated concrete samples with different steel bar diameters. In this paper, the “origin of magnetic flux leakage signal” is defined as a reference point, which is convenient for effectively comparing the magnetic signal curves under all operating conditions. Besides, the “rust-magnetic fluctuation parameter” is proposed to accurately reflect the sudden change of leakage magnetic field caused by disconnection due to the corrosion of a steel bar. A new data processing method is provided for the non-destructive testing of steel corrosion using the spontaneous magnetic flux leakage effect, which can effectively reduce the influence of steel bar diameter on magnetic flux leakage signal and improve the precision of non-destructive testing technology of steel bar corrosion using the metal magnetic memory effect.

Study on the Magnetic Flux Leakage (MFL) for Fillet Weld

2012 ◽  
Vol 472-475 ◽  
pp. 2311-2314
Author(s):  
Chun Fei Guo ◽  
Li Jun Wang ◽  
Min Zhang
Keyword(s):  
Magnetic Flux ◽  
Air Gap ◽  
Magnetic Flux Leakage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Fillet Weld ◽  
Weld Structure ◽  
Magnetic Poles ◽  
Non Destructive ◽  
Flux Leakage

The magnetic flux leakage (MFL) technique is widely used as a Non-Destructive Testing (NDT) method for welds [1]. Because of the specialty of fillet weld structure, the defect may not be in the location suitably detected, which is normally at the center of yoke poles, and the rate of detect-ability would decline. In this paper, we focus on the yoke-magnetization testing for a fillet weld, and it is studied the influences of air gap between magnetic poles and specimen surface on MFL density at an artificial flaw by Finite Element Method (FEM), and also the influences of distance between magnetic poles and fillet weld on MFL density. The results show that the MFL density observably decreases as the air gap and the distance increase.

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