A comparative investigation of the efficacy of CO2 and high-power diode lasers for the forming of EN3 mild steel sheets

A comparative investigation of the effectiveness of a high-power diode laser (HPDL) and a CO2 laser for the forming of thin-section EN3 mild steel sheet has been conducted. The buckling mechanism was identified as the laser forming mechanism responsible for induced bending. For both lasers it was found that the induced bending angles increased with an increasing number of irradiations and high laser powers, while decreasing as the traverse speed was increased. Also, it was apparent from the experimental results that the laser bending angle was only linearly proportional to the number of irradiations when the latter was small due to local material thickening along the bend edge with a high number of irradiations. Owing to the mild steel's greater beam absorption at the HPDL wavelength, larger bending angles were induced when using the HPDL. However, under certain conditions the performance of the CO2 laser in terms of induced bending angle was seen to approach that of the HPDL. Nevertheless, similar results between the two lasers were only achieved with increasing irradiations; thus it was concluded that the efficacy of the HPDL was higher than that of the CO2 laser insofar as it was more efficient. From graphical results and the employment of an analytical procedure, the laser line energy range in which accurate control of the HPDL bending of the mild steel sheets could be exercised efficiently was found to be 53 J/mm < P/upsilon < 78 J/mm, while for the CO2 laser the range was 61 J/mm < P/upsilon < 85 J/mm.