Study on porosity formation in laser welds in aluminium alloys (Report 1) : Effects of hydrogen and alloying elements

摘要: Summary The CO2 laser welding of aluminium alloys, A3003, A6061, A6N01, A5052, A5083 and A5182, was carried out at different speeds the behaviour porosity formed in welds investigated to make clear mechanism formation. Three types were observed. observed number voids (Type A) less than 50μm diameter decreased with an increase speed solidification rate because lack time for nucleation growth gas bubbles during welding. According analysis A6N01 hydrogen about 90 vol% total gases rest nitrogen. And A5182 alloy deeper penetration, a small amount helium, used as shielding gas, also detected. Besides, Al-Mg majority along solute band Mg enrichment. induced polygonal C) larger ...