Effects of laser welding heat input on the formability

microstructure

mechanical properties and fracture morphology of Mg-3 Nd-0.2 Zn alloy welded joint were investigated

and the action mechanism of Nd element was expounded.The results reveal that when the welding heat input is less than 84 J/mm

weld joint is not penetrated

and with the increase of welding heat input

the welding penetration is increased gradually.In addition

when the welding heat input is increased to 84 J/mm and above

the welding joint is permeable

and with the increase of heat input

the welding width between the surface and the lower surface of the weld joint is increased.With the increase of welding heat input

the heat affected zone width and grain size of welded joints show a trend of gradual increase.When the welding heat input is less than 84 J/mm（unmelted）

the change of width of heat affected zone and grain size can be ignored.When the welding heat input is greater than or equal to 84 J/mm（penetration）

tensile strength and elongation welding joint reach more than 85% and 87% of the parent material under three kinds of welding heat input.Under the condition of full penetration

the increase of welding heat input will reduce the strength and plasticity of welded joint

and the desirable strength and plasticity can be obtained when the welding heat input is 84 J/mm.