Open Access
Review
Table 1
Summary of process–microstructure–property map between traditional and advanced fabrication methods for LDS.
| Process route | Purity/In clusion control | Segregatio n in LDS | Grain structure | Porosity | Relevant microstru ctural features | Resulting properties | Advantages | Drawbacks | Suitability for LowDensity Steel | Reference |
|---|---|---|---|---|---|---|---|---|---|---|
| VIM | Low oxygen, sulfur, and nitrogen content | Moderate segregation; Mn/Al segregation possible | Coarse columna ?/dendrit ic; fine-tomedium after working | Low | Good κ carbide control; duplex ferriteaustenite, but dendritic | Lower fatigue resistance (inclusiondriven), moderate strength; corrosion susceptibility when carbides/incl usions form | Good purity, suitable for lab-scale LDS; effective for highmelting alloys | Energyintensive; coarse dendrites; requires forging/rolling; sensitive to carbide networks (M.C, MzCc); inclusion risk; limited complex shapes | Suitable for small/medi um batches; good for alloy developme nt | [26,67,69, 72,78] |
| VAM | Extremel y low impuritie 5; very clean melt | Very low segregation | Fine, uniform dendriti c grains | Very low | Excellent k-carbide uniformit y; suppresse d unwanted carbides | Very high fatigue strength, hardness, creep resistance | Highest purity: multiple remelts; very homogeneo us LDS | Very high cost; small ingot size; limited complex shapes; carbide risks remain if chemistry is poor | Excellent for highend LDS research and medicalgrade alloy developme nt | [26,67,69, 72,78] |
| NNS | Higher inclusion s; oxide | Strong macro/micr | Coarse, inhomo geneous | High | k-carbides heavily segregate | Lowmoderate strength; carbide-rich | Low cost; large complex shapes; | High risk of porosity; retained inclusions; | Good for complex shapes but not ideal | [65, 88, 90–93] |
| films possible | 9segresatio n. | columna I grains | ; poor ferrite/au stenite distributi on | zones pit easily | minimal machining | poor microstructure control; may need heat treatment | for highperformanc e LDS | |||
| MA+ SPS | Very low impuritie s if the powders are clean | Minimal segregation (solid-state alloying) | Ultrafin enamo equiaxe d grains | Very low; near-full density | Uniform, refined nonequilibriu m phases (k, B 2); stable duplex structure | Extremely high strength and hardness; moderate ductility; improved corrosion due to refined carbides | Very high strength/tou ghness; low porosity; excellent microstructu re control | Limited component size; milling contamination risk; requires tooling; MA step adds complexity | Excellent for advanced LDS microstruct ures biomedical property tuning | [53,98,101] |
| AM | Powder contamin ation possible; moderate inclusion risk | Fine cellular segregation; element yaporisatio. n (Al) | Very fine grains; strong texture & anisotro py | Moderate; lack of fusion + gas porosity | Cellular solidifica tion refines k carbides; high dislocatio n density | Very high strength (grain refinement; anisotropic ductility; moderate corrosion | Complex geometries; lightweight designs; tunable microstructu re; in-situ alloying | Anisotropy; residual stresses; powder cost; porosity; surface roughness; Al evaporation | Excellent for complex LDS biomedical component 5 | [46,48,102,105] |
VIM: Vacuum induction melting, VAM: Vacuum arc melting, NNS: Near Net Shape, MA: Mechanical alloying, SPS: Spark plasma sintering, AM: Additive manufacturing.
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