Effect of Nd-YAG Laser Pulse Shaping on Weld Bead Characteristics of Different Materials

摘要

Laser Pulse shaping was found to effect the weld bead characteristics. Versatility of laser welding is further increased with pulse shaping. Pulse shaping can be effectively used to reduce defect generation, cracking susceptibility and to reduce heat input. Pulsed Nd-YAG laser welding is associated with many variables such as peak power, pulse duration, pulse energy, defocusing distance, spot overlapping, frequency and pulse shape. Shaping of laser pulse to get the desired weld bead geometry is getting importance. Shaping of laser pulse includes ramping up, ramping down, initial peak etc. Selection of pulses has also been discussed. Absorption of laser depends upon type of material and its surface roughness. Weld bead geometry changes with material and surface finish at a constant pulse energy. In this paper effect of pulse shaping on different materials has been discussed. Study has been carried out using optical microscopy. Optical microscopy is used to analyze the changes in metallurgical structure. Distinct differences in weld bead geometry have been observed with temporal pulse shaping technique. Effect of shaping on reduction of defects has also been discussed.