2524 aluminum alloy was carried out by optical fiber laser welding test and the influence of welding speed on the microstructure and mechanical properties of optical fiber laser welding joint was investigated by means of microstructure analysis

X-ray diffraction

tensile and hardness testing.The results illustrate that the welding speed has a significant effect on the joint.With the low welding speed

the heat input will be increased so that the weld joint can be collapsed.On the contrary

the lack of heat input will result in the joint welded incompletely.With the decrease of heat input

the weld width is decreased gradually

and the size of equiaxial dendritic crystals in the center of the weld is decreased

and the area of columnar dendritic crystals in the fusion zone becomes narrower.Meanwhile

the dendritic spacing is decreased

and the growth direction is enhanced.In the unidirectional tensile testing

the tensile strength of the joint is increased with the increase of welding speed

and it reaches up to the maximum value of 329.21 MPa at 75 mm/s

which is 73.15% of the base metal.The hardness curve of the joint presents U-shaped distribution

and the softening presents the most severe in the weld center.