Additive manufacturing of metallic components – Process, structure and properties

Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or binder jetting. However, we do not have any guidelines that discuss the selection of the most suitable additive manufacturing process, depending on the material to be processed, the complexity of the parts to be produced, or the design considerations. Considering the very fact that no reports deal with this process selection, the present manuscript aims to discuss the different selection criteria that are to be considered, in order to select the best AM process (binder jetting/selective laser melting/electron beam melting) for fabricating a specific component with a defined set of material properties.

Additive Manufacturing Processes: Selective Laser Melting, Electron Beam Melting and Binder Jetting-Selection Guidelines.

Simultaneous enhancements of strength and toughness in an Al-12Si alloy synthesized using selective laser melting

Formation of metastable cellular microstructures in selective laser melted alloys

Residual Stress in Metal Additive Manufacturing

Inconel-718 has received an extensive using in mold industry. The selective laser melting (SLM) is providing an ideal means for manufacturing mold insert with complex geometrical features and internal architecture. During the manufacturing of high quality mold inserts with conformal cooling channel, the parameters play a vital role in the SLM process. In the study, the Inconel-718 alloys were manufactured by SLM with 2×2 mm 2 , 3×3 mm 2 , 5×5 mm 2 , and 7×7 mm 2 island scanning strategies. The microstructure, mechanical property, and residual stress were investigated by optical microscope, tensile test and Vickers micro-indentation, respectively. It can be found that the relative density increased with enlarging the island size; the results on the microstructure indicated that the cracks and more pores were detected in the 22-specimen; whilst the microstructures of all specimens were composed of fine dendritic grains, cellular, and columnar structures; the tensile testing suggested that the ultimate tensile strength and yield strength of all samples was similar; while the outcome of the residual stress showed that the value of residual stress was ranked in the following sequence: 22-specimen

Study on the microstructure, mechanical property and residual stress of SLM Inconel-718 alloy manufactured by differing island scanning strategy

Dyeing of cotton fabric with reactive disperse dye contain acyl fluoride group in supercritical carbon dioxide

A series of reactive disperse dyes incorporating halogenated acetamide group were synthesized and applied to dye cotton fabric in supercritical carbon dioxide (scCO2). Dyeing experiments were conducted in scCO2 with dye concentration of 0.5% owf (% on weight of cotton fabric), varying from 80 to 120 °C, for 1–3 h at a constant pressure of 200 bar. The results showed that the color strength of dyed cotton fabric increased favorably when increasing temperature and time. The color characteristics were studied as well in terms of the reflectance spectra. And the color fastness to washing and rubbing were also reasonably good.

Synthesis of reactive disperse dyes containing halogenated acetamide group for dyeing cotton fabric in supercritical carbon dioxide

Supercritical carbon dioxide (SC-CO2) dyeing for the polyethylene terephthalate (PET) and cotton fabric was implemented by a modified dynamic-recirculation apparatus that was successfully designed and constructed in our laboratory. This energy-efficient apparatus contains two horizontal dyeing vessels and equips the rotating warp beam. The circulating SC-CO2 fluid and revolving fabrics facilitate the uniform adsorption and quick uptake of dye molecules to the fabrics. Moreover, three dyes were synthesized and applied for dyeing fabric samples performed in mild conditions of 353.2 K and 18.0 MPa for 60 min in SC-CO2. Satisfactory and commercially acceptable products with reasonably good color uniformity, color strength and color fastness were obtained in dyeing experiments with this SC-CO2 apparatus. Color characteristics of the dyed PET and cotton fabrics such as the absorption and reflectance spectra were determined, and their surface morphologies were investigated by scanning electron microscopy.

Supercritical Carbon Dioxide Dyeing for PET and Cotton Fabric with Synthesized Dyes by a Modified Apparatus

Solubilities of the reactive disperse dyes synthesized with the reactive group of 1,3,5-trichloro-2,4,6-triazine were investigated in supercritical carbon dioxide (SC-CO2) at pressures of 10.0–25.0 MPa, temperatures of 333.2–393.2 K, and equilibrium contact time of 60 min. Meanwhile, dyeing experiments of cotton fabrics by using these dyes were performed at 373.2 K and 20.0 MPa for 60 min with a dye concentration of 0.5% owf in SC-CO2. Solubilities of these dyes increased with increasing pressure and decreasing temperature. Additionally, the color strength and the color fastness of dyed cotton fabrics were measured, and reasonably good dyeing effects were obtained. Furthermore, the color characteristics of dyed cotton fabrics were studied in terms of the reflectance spectra, and their surface morphologies were investigated by SEM as well.

Huang Tingting

Papers

Study on the microstructure, mechanical property and residual stress of SLM Inconel-718 alloy manufactured by differing island scanning strategy

Dyeing of cotton fabric with reactive disperse dye contain acyl fluoride group in supercritical carbon dioxide

Synthesis of reactive disperse dyes containing halogenated acetamide group for dyeing cotton fabric in supercritical carbon dioxide

Supercritical Carbon Dioxide Dyeing for PET and Cotton Fabric with Synthesized Dyes by a Modified Apparatus

Synthesis and Measurement of Solubilities of Reactive Disperse Dyes for Dyeing Cotton Fabrics in Supercritical Carbon Dioxide