Magnetic Field Measurements during Magnetic Pulse Welding Using CMR-B-Scalar Sensors

Abstract

The possibility of applying CMR-B-scalar sensors made from thin manganite films exhibiting the colossal magnetoresistance effect as a fast-nondestructive method for the evaluation of the quality of the magnetic pulse welding (MPW) process is investigated in this paper. This method based on magnetic field magnitude measurements in the vicinity of the tools and joining parts was tested during the electromagnetic compression and MPW of an aluminum flyer tube with a steel parent. The testing setup used for the investigation allowed the simultaneous measurement of the flyer displacement, its velocity, and the magnitude of the magnetic field close to the flyer. The experimental results and simulations showed that, during the welding of the aluminum tube with the steel parent, the maximum magnetic field in the gap between the field shaper and the flyer is achieved much earlier than the maximum of the current pulse of the coil and that the first half-wave pulse of the magnetic field has two peaks. It was also found that the time instant of the minimum between these peaks depends on the charging energy of the capacitors and is associated with the collision of the flyer with the parent. Together with the first peak maximum and its time-position, this characteristic could be an indication of the welding quality. These results were confirmed by simultaneous measurements of the flyer displacement and velocity, as well as a numerical simulation of the magnetic field dynamics. The relationship between the peculiarities of the magnetic field pulse and the quality of the welding process is discussed. It was demonstrated that the proposed method of magnetic field measurement during magnetic pulse welding in combination with subsequent peel testing could be used as a nondestructive method for the monitoring of the quality of the welding process.

Engineering of Advanced Materials for High Magnetic Field Sensing: A Review

“…The signal is synchronized and recorded simultaneously by recording channels. The magnetic field measurement system was used for measurements of magnetic field distribution and diffusion during operation of electromagnetic launchers [ 18 , 89 , 90 ], highly inhomogeneous transient fields in a coil gun [ 91 ], field distribution in nondestructive pulsed magnets [ 92 ], welding quality control in magnetic forming and welding systems [ 93 ]. Despite the fact that the resistance of manganite film, which is a basic element of the sensor, is dependent on ambient temperature, the CMR-B-scalar sensors can be successfully calibrated in advance in a wide range of temperatures (see Figure 13 b) and the data are stored in the software of the system what allows simultaneous conversion of the measured signal (voltage) to magnetic field values [ 10 ].…”

Comprehensive Weldability Criterion for Magnetic Pulse Welding of Dissimilar Materials

“…Experimental measurement of the impact velocity in MPW was largely conducted using optical methods, particularly with the use of a photonic Doppler velocimeter (PDV) [44,45]. In their previous work, the authors validated the FEM employed in this study by comparing the simulated impact velocity with the experimental impact velocity measured using PDV for various process conditions.…”

Enhancement of Room-Temperature Low-Field Magnetoresistance in Nanostructured Lanthanum Manganite Films for Magnetic Sensor Applications

“…It was demonstrated that nanostructured La 1−x Sr x MnO 3 (La-Sr-Mn-O, LSMO) manganite films can be used for the development of magnetic sensors, which are capable of measuring the magnitude of pulsed magnetic fields in very small volumes (so-called CMR-B scalar sensors) up to very high magnetic fields [8,14]. Such sensors were used for the magnetic field measurement during electromagnetic acceleration in railguns and superconducting systems [15,16], the magnetic field distribution in non-destructive pulsed-field magnets [17], and evaluation of welding quality during magnetic welding of metals [18]. The possibility to tune temperature and magnetic field ranges of operation of CMR sensors by changing deposition temperature and film thickness was demonstrated [19].…”