Magnetic Nondestructive Testing Techniques of Constructional Steel

Abstract

Steel is a kind of ferromagnetic material, which is extensively applied in such fields as buildings, bridges, railways, machines and lifeline engineering etc. Those engineering structures built of constructional steel will unavoidably experience some damages during their service lifetime, thus which will influence the distribution regularity of internal forces in structures, result in over-stresses, cause the local failure of structures, and even lead to collapse of the whole structure. Therefore, it is a pressing topic to study how to directly evaluate the real-time stressed states of structural members, damages and steel characteristics in present structural health monitoring and diagnosing fields. And the achievements of this research will be of theoretical significance and of application value of engineering. This paper summarizes varieties of new magnetic nondestructive testing techniques used in constructional steel, respectively investigates the testing principles, characteristics and application for the magnetic Barkhausen noise technique, magnetic acoustic emission technique, magnetic flux leakage technique, magnetic memory technique and magnetic absorption technique, and points out the problems present in the application of these new techniques to actual testing and the further research objective.

Fluxgate Sensor with Bifactor Excitation Mode

“…As most industrial equipment and production systems have components made of ferromagnetic structural materials such as steel or cast iron, the magnetic measurement-based NDT of their quality is most advisable [ 7 , 8 , 9 , 10 , 11 ]. We can specify the following examples of the most common and critical objects containing ferromagnetic components requiring periodic NDT during the entire service life without violating their functions: lifting mechanisms containing steel cables and ropes [ 12 , 13 ], power transmission lines based on, e.g., cables with steel-aluminum wires or ferromagnetic shields [ 14 ], steel or cast-iron pipelines [ 15 ], and various rolled metal products (sheet, section, shaped) [ 16 , 17 ].…”