Effects of laser welding parameters on magnetic materials with the aid of a mechatronic measuring system

This article reports results from an experimental investigation into laser welding of ferromagnetic material, which, for example, is of interest to the European Space Agency. The effects of laser welding power and translation velocities on the magnetism of ferromagnetic materials were studied. An automated system using a Hall effect transducer was constructed to measure the magnetic field transverse to the laser weld before welding, immediately after welding and three days after welding. The results show that immediately after welding the magnetization of the melt pool and heat affected zone are decreased, with the greatest decrease occurring in the weld. Interestingly, after a period of three days, during which the samples were isolated, the magnetization in the area adjacent to the weld had recovered. Specimens of iron magnet were used for the experiments; Ferranti’s MFKP 1.2 kW CO2 and GSI Lumonics Nd3+ yttrium–aluminum–garnet (YAG) lasers were utilized to weld the specimens. From both Nd3+ YAG and CO2 laser welding results, it can be concluded that at high workpiece translation speeds an optimized laser power should be used in order to minimize the size of the demagnetized zone. We also found that the specimens welded with the Nd3+ YAG pulsed laser show a better remagnetization rate and recovery than the specimens welded with the continuous wave CO2 laser.