[2A6] Development of eddy current transducer for testing of penetration depth of end weld seams on steel plates of ITER resistive elements
P Solomenchuk and V Syasko
Constanta Ltd, Russia
The existing technological documentation regulates one hundred percent inspection of penetration depth of end weld seams on steel ferromagnetic plates of resistive elements ITER.
It seems optimal to use the eddy-current phase-sensitive method for these purposes. To reduce the magnetic permeability µ of the metal of the plates and the weld seam, in order to ensure the required penetration depth of eddy currents, it is proposed to use magnetization to saturation of the inspected area with the use of a compact electromagnet. To optimize the parameters of the electromagnet, studies of the magnetic properties of steel in a strong constant and a weak alternating magnetic field were carried out. The value of the induction of the magnetic saturation and the dependence of µ on the frequency of the magnetic field have been set.
On the basis of research and modelling using the finite element method with the use of automatic algorithms, an eddy-current transducer with an electromagnet has been developed. It magnetizes the weld seam with a constant magnetic field (induction not less than 2.2 T), that allows to inspect the penetration depth of the weld seam up to 1.4 mm at an excitation current frequency 50 kHz.
The transducer is used as part of a 6-axis manipulator with a lifting capacity of 3 kg. To ensure the required temperature of the electromagnet, liquid cooling and special laying of wire windings are used.
The principles, modelling results and also the main technical characteristics of the transducer and the results of its testing in production are described in detail in the paper.
It seems optimal to use the eddy-current phase-sensitive method for these purposes. To reduce the magnetic permeability µ of the metal of the plates and the weld seam, in order to ensure the required penetration depth of eddy currents, it is proposed to use magnetization to saturation of the inspected area with the use of a compact electromagnet. To optimize the parameters of the electromagnet, studies of the magnetic properties of steel in a strong constant and a weak alternating magnetic field were carried out. The value of the induction of the magnetic saturation and the dependence of µ on the frequency of the magnetic field have been set.
On the basis of research and modelling using the finite element method with the use of automatic algorithms, an eddy-current transducer with an electromagnet has been developed. It magnetizes the weld seam with a constant magnetic field (induction not less than 2.2 T), that allows to inspect the penetration depth of the weld seam up to 1.4 mm at an excitation current frequency 50 kHz.
The transducer is used as part of a 6-axis manipulator with a lifting capacity of 3 kg. To ensure the required temperature of the electromagnet, liquid cooling and special laying of wire windings are used.
The principles, modelling results and also the main technical characteristics of the transducer and the results of its testing in production are described in detail in the paper.
