The Inconel 718 alloy was fabricated by selective laser melting with different scanning speeds and modes.The effects of process parameters on molten-pool morphology

solidification structure

grain growth and grain orientation were investigated.The results indicate that the depth-width ratio of the molten-pool is increased and the curvature is decreased with the increase of the scanning rate

while the ratio with the single-direction scanning is greater than that with the decussation scanning at 1 450 mm/s.In the molten pool

the solidified structure is converted from the cell crystal at the bottom to the cell dendrite on the side of the molten pool.The grains are grown along the preferred orientation of<001>direction

and the misorientation is dominated by small-angle misorientation（<15°）.The fraction of small-angle misorientation is increased with the scanning rate increase under the decussation scanning mode.When scanning rate is constant

the fraction of the small-angle misorientation is 62.57% under the decussation scanning mode

while that under single-direction scanning mode is 47.69%.