Lap Fillet Laser Welding of AZ31B Thin Sheet Magnesium Alloy using Silver Nanoparticles

概要

論文の詳細を見る
In this paper, the use of silver nanoparticles paste has been proposed to laser-weld AZ31B magnesium alloy with a thickness of 0.3 mm. The paste containing Ag nanoparticles of 5 nm in average diameter and an organic solvent was used to coat the surface of AZ31B thin sheet by a spin coater. The coated sheet was heated at 100 °C for 60 s to evaporate the solvent. The dried sheet was set as a lower AZ31B sheet on the jig, and then lap fillet welding was carried out by using a pulsed Nd:YAG laser in a closed box filled with argon gas. Characteristics of microstructure and mechanical properties of the joint were investigated. When the Ag nanoparticles paste was used, parameters for welding the thin AZ31B sheet were identified: a pulse energy of 1.8 J, pulse duration 3.0 ms, pulse repetition rate 80 Hz, and scan speed between 7.5 mm/s (450 mm/min) to 10.8 mm/s (650 mm/min). Under these conditions, the bond width improves, defects reduce and process parameters range broadens compared to welding without using the paste. Besides, the area of high hardness widens due to the increase of the fine grain area and the decrease of the heat affected zone. Weld joint efficiency also improves up to 92 % of the base metal.