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| Effects of Particle Size on Microstructures and Properties of GH4169 Alloy by SLM Additive Manufacturing |
| CHEN Shiqi, LIU Lianping |
| （State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China) |
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Abstract 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 yield strength R p0.2 and tensile strength Rm 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 Rm.
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2021, 
