Abstract
Laser welding has been considered as a promising method to join sintered NdFeB permanent magnets thanks to its high precision and productivity. However, the influences of laser welding on the magnetic property of NdFeB are still not clear. In the present paper, the effects of laser power on the remanence (Br) were experimentally investigated in laser spot welding of a NdFeB magnet (N48H). Results show that the Br decreased with the increase of laser power. For the same welding parameters, the Br of magnets, that were magnetized before welding, were much lower than that of magnets that were magnetized after welding. The decrease in Br of magnets after laser welding resulted from the changes in microstructures and, in turn, the deterioration of magnetic properties in the nugget and the heat affected zone (HAZ) in a laser weld. It is recommended that the dimensions of nuggets and HAZ in laser welds of a NdFeB permanent magnet should be as small as possible, and the magnets should be welded before being magnetized in order to achieve a better magnetic performance in practical engineering applications.
Highlights
NdFeB rare earth permanent magnets have been widely used in many industrial fields, such as aeronautics, astronautics, automotive, appliance, computers, and communications, thanks to their excellent magnetic property [1,2,3]
Owing to the high power density, the laser generally results in welds with high precision and a small heat affected zone (HAZ) and, is considered as a good candidate to join the tiny sintered NdFeB components
The cross‐sections of laser spot ofWeld the magnet were observed by SEM
Summary
NdFeB rare earth permanent magnets have been widely used in many industrial fields, such as aeronautics, astronautics, automotive, appliance, computers, and communications, thanks to their excellent magnetic property [1,2,3]. Sintered NdFeB permanent magnets are brittle and with poor mechanical properties. Microstructures and mechanical behavior have been studied for laser welds of NdFeB magnets [21] and laser welds of dissimilar materials of a NdFeB magnet and mild steel [22]. It is still not clear how the laser welding will affect the magnetic property and how the optimal magnetic performance can be obtained. The magnetic property and performance are critical for the NdFeB permanent magnetic functional material in engineering applications, which makes it stringent to understand the change in the magnetic response of NdFeB when subject to laser welding processing.
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