Experimental study of magnetic field-aided friction stir spot welding

چکیده مقاله

Magnetic field is applied during the friction stir spot welding of St37 steel to achieve a better microstructure and mechanical properties. The process is called magnetic field-aided friction stir spot welding. The magnetic field is applied using an induction heater module and coil in which the welding tool acts as the core for the coil. Effects of tool rotational speed, voltage, and dwell time are investigated on the strength and microstructure of welded samples. The strength of joints increased using a magnetic field and the effect is stronger when a lower tool rotational speed and dwell time is used. This could be contributed to the heat input by applying Eddy current in the nugget together with a finer microstructure which is achieved the applying the magnetic field. The increase of all three parameters simultaneously overheats the nugget and results in a drop in the strength of the joint. The highest strength of 5159.5 N is achieved with a tool rotational speed, dwell time, and voltage of 2000 rpm, 6 s, and 25 V, respectively.