The control method of porous structure for density gradient materials in direct metal laser sintering (DMLS)

The effect of process parameters in direct metal laser sintering (DMLS) on the forming of density gradient porous structure was investigated. The melted and consolidated parts of metallic powders by laser irradiation (it is called as melted part in this paper) sparsely form along the laser scanning line. The size of melted part strongly depends on the laser input energy. During the direct metal laser sintering, the melted parts conglutinate with each other and made the larger melted part. It was connected to other melted parts in different way by strong laser power and high scan rate. Especially, in the case of same laser energy density, if the scan rate become faster, the connection between melted parts gets stronger and the high density is obtained. With laser sintering condition for similar relative density, the microstructure of material formed by higher scan rate shows more homogeneous microstructure than that of the others formed by slow scan rate.