Magnetic field and ultrasonic aided laser drilling effect on Ti6Al4V microstructural characteristics

Today, the utilization of millisecond pulse laser drilling, despite the extensive applications in different fields, is accompanied by several limitations such as low penetration depth, high thickness of recast layer, and heat-affected zone. In order to overcome these limitations, different techniques such as applying magnetic field as well as utilizing ultrasonic vibrations have been proposed. Up to now, limited investigations have been conducted regarding the effect of simultaneous addition of magnetic field and ultrasonic vibration on microstructural characteristics; therefore, in this paper, the simultaneous effects of magnetic field (0.5 Tesla intensity) and ultrasonic vibrations (with the frequency of 28 kHz and amplitude of 15 mu m) on the formed phases, recast layer and heat-affected zone thickness have been studied in laser drilling of Ti6Al4 V. According to the results, 23.53% and 6.31% reductions were obtained in diameter and depth of the drilled hole compared to conventional laser drilling, respectively. Moreover, the diameter of heat-affected zone, in the inlet of the drilled hole, was reduced by 30.33% in this hybrid process compared to conventional laser drilling. Besides, it was observed that the presence of ultrasonic vibrations prevents from the formation of acicular alpha structure in the recast region of Ti6Al4 V.