Analysis of microstruc ture and mechanics performance of laser butt-weld for Al-Mg alloy

The laser butt-weld of fine-grained 5083 Al alloy sheets without filler is investigated with 3 kW CO₂ laser in this paper.The influence of laser power,welding speed on the surface quality of weld is analyzed.The microstructure,mechanical properties and high temperature forming properties of welded joint are further studied.The experimental results show that the welding surface with high quality is obtained under appropriate laser power and welding speed.The profile of microhardness traverse across the weld exhibits like W shape and the heat affected zone(HAZ) has serious softening.The results of high temperature tension show that the tensile strength of welded joint is greater than the base metal,which is the side of fractures.Optimal relative height of 0.59 of the free bulging sample is obtained at 500℃.This result shows that laser butt-welding sheets of fine-grained 5083 Al alloy possess good high temperature formability.