To investigate the influence of raw GH4169 alloy particle size on microstructures and properties of AM moldings

two kinds of alloy powder with different particle size range were selected for selective laser melting experiment

and samples were heat treated under the same conditions. Density and tensile properties were analyzed for both as-deposited and heat-treated samples. All samples’ microstructures

fracture morphologies and precipitates were observed by OM and SEM. The results indicate that the density of coarse powder in as-deposited samples is higher than that of fine powder

and samples with fine powder have higher yiel

d strength R

p0.2

and tensile strength R

m

in heat-treated. However

as-deposited and heat-treated samples with coarse powder exhibit higher elongation. What’s more

the as-deposited samples’ molten pool has a configuration of fish scales along the deposition direction

and samples with fine powder have more irregular molten pools than coarse powder. Meanwhile

solidification of molten pool starts from interface and inherits the structural characteristics of solidified molten pool

possessing structure genetic characteristic. Microstructure of both samples shows no significant difference

indicating the size of powder particles has no obvious effects on their microstructures. The equiaxed grain microstructures formed after the heat treatment reduce defects

meanwhile precipitated phase appears

which are main factors for the increasing of R

p0.2

and R

m

.