Optimization and comparison of porosity rate measurement methods of Selective Laser Melted metallic parts

Terris, Thibaut de; Andreau, Olivier; Peyre, Patrice; Adamski, Frédéric; Koutiri, Imade; Gorny, Cyril; Dupuy, Corinne

doi:10.1016/j.addma.2019.05.035

Cited by 75 publications

(60 citation statements)

References 33 publications

(56 reference statements)

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“…As previously mentioned, in the case of 316 L steel after SLM, there is always a certain proportion of porosity, and the content of which significantly depends on the used conditions [ 2 , 5 , 6 , 9 , 12 ]. Figure 13 shows the different levels of porosity in the structure of the samples prepared under different SLM conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Three types of the porosity have been defined to date. The first type of porosity is caused by insufficient or imperfect melting of particles (lack of fusion (LOF) porosity), exhibits angular and random morphologies with a large size of up to 500 µm and usually contains unmelted powder [ 6 ]. LOF porosity arises due to the small variance in the energy density of the laser across the surface of the layer and can be partially corrected by changing the process parameters.…”

Section: Introductionmentioning

confidence: 99%

“…The other two types of porosity arise due to gas entrapment by surface turbulence. Blowhole porosity is characteristic by an oval shape and small size of up to ten micrometers, and the third type is keyhole porosity, which arise from the collapse of keyhole walls usually at higher laser intensity, and it is characteristic by larger dimensions than blowhole porosity [ 6 , 7 , 8 ]. In the case of turbulent capturing the gas, where evaporation of the material or gas of the protective atmosphere leads to porosity, it can be very difficult to correct [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Hot Isostatic Pressing on Porosity and Mechanical Properties of 316 L Stainless Steel Prepared by the Selective Laser Melting Method

et al. 2020

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The manufacturing route primarily determines the properties of materials prepared by additive manufacturing methods. In this work, the microstructural features and mechanical properties of 316 L stainless steel prepared by the selective laser method have been determined. Three types of samples, (i) selective laser melted (SLM), (ii) selective laser melted and hot isostatic pressed (HIP) and (iii) selective laser melted and heat treated (HT), were characterized. Microstructural analysis revealed that SLM samples were formed by melt pool boundaries with fine cellular–dendritic-type microstructure. This type of microstructure disappeared after HT or HIP and material were formed by larger grains and sharply defined grain boundaries. The SLM-prepared samples contained different levels of porosity depending on the preparation conditions. The open interconnected LOF (lack of fusion) pores were observed in the samples, which were prepared with using of scanning speed 1200 mm/s. The blowhole and keyhole type of porosity were observed in the samples prepared by lower scanning speeds. The HIP caused a significant decrease in internal closed porosity to 0.1%, and a higher pressure of 190 MPa was more effective than the usually used pressure of 140 MPa, but for samples with open porosity, HIP was not effective. The relatively high yield strength of 570 MPa, tensile strength of 650 MPa and low ductility of 30–34% were determined for SLM samples with the lower porosity content than 1.3%. The samples after HIP showed lower yield strengths than after SLM (from 290 to 325 MPa) and relatively high ductility of 47.8–48.5%, regardless of the used SLM conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Hot Isostatic Pressing on Porosity and Mechanical Properties of 316 L Stainless Steel Prepared by the Selective Laser Melting Method

et al. 2020

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“…The measurement of porosity had been performed using the Archimedes method [33,34]. An as-built sample with a dimension of 10 mm × 10 mm × 10 mm was used, and distilled water was chosen as the fluid.…”

Section: Microstructure and Porosity Characterizationmentioning

confidence: 99%

“…It can be seen from Table 3 that the maximum density is inferior to 99%, which is lower than the data reported by Galarraga et al [35] There are two possible reasons for the lower relative density of these samples: (1) there are a small number of holes on the surface of the samples, which reduces the densification of the material; (2) in this study, the Archimedes method was used to measure the density of the samples. The results of the Archimedes method depend on the nature and temperature of the fluid, but also on the sample volume and its surface roughness [34]. However, the side surfaces of the samples built by electron beam melting were rough due to some partially melted powder particles adhered to the side surfaces, which makes the volume of the samples larger than they should be, so its density may be lower.…”

Section: Microstructure and Relative Density Of Ti-6al-4v Alloy Produmentioning

confidence: 99%

Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by Electron Beam Melting

et al. 2020

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Electron beam melting technique is a kind of near-net shaping, environmentally friendly metal additive manufacturing technique, which can form high-performance metal parts with complex shapes. It has been widely applied in the aerospace industry, biomedical application, automobile manufacturing, and other fields. Ti-6Al-4V is the most widely researched and applied alloy in the additive manufacturing field, but its microstructure is diverse, and its mechanical properties vary greatly. In this study, the effect of process parameters on the microstructure and the resulting mechanical properties of Ti-6Al-4V alloy was researched. The results show that the yield strength of Ti-6Al-4V alloy with a bimodal microstructure is higher than those with a basketweave microstructure. Energy dispersion spectrum (EDS) line scan and area scan results show that there is no element enrichment for the specimens with the highest yield strength. A speed factor of less than 40 is a must for obtaining relatively dense Ti-6Al-4V parts built with electron beam melting. We have done basic research for the subsequent manufacturing of complex shape parts, which is helpful to promote the application of electron beam melting technology in the aerospace field.

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Transparent Porous Conductive Substrates for Gas‐Phase Photoelectrochemical Hydrogen Production

et al. 2023

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Gas diffusion electrodes are essential components of common fuel and electrolysis cells but are typically made from graphitic carbon or metallic materials, which do not allow light transmittance and thus limit the development of gas‐phase based photoelectrochemical devices. Herein, the simple and scalable preparation of F‐doped SnO2 (FTO) coated SiO2 interconnected fiber felt substrates is reported. Using 2–5 µm diameter fibers at a loading of 4 mg cm−2, the resulting substrates have porosity of 90%, roughness factor of 15.8, and Young's Modulus of 0.2 GPa. A 100 nm conformal coating of FTO via atmospheric chemical vapor deposition gives sheet resistivity of 20 ± 3 Ω sq−1 and loss of incident light of 41% at illumination wavelength of 550 nm. The coating of various semiconductors on the substrates is established including Fe2O3 (chemical bath deposition), CuSCN and Cu2O (electrodeposition), and conjugated polymers (dip coating), and liquid‐phase photoelectrochemical performance commensurate with flat FTO substrates is confirmed. Finally, gas phase H2 production is demonstrated with a polymer semiconductor photocathode membrane assembly at 1‐Sun photocurrent density on the order of 1 mA cm−2 and Faradaic efficiency of 40%.

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Optimization and comparison of porosity rate measurement methods of Selective Laser Melted metallic parts

Cited by 75 publications

References 33 publications

Effect of Hot Isostatic Pressing on Porosity and Mechanical Properties of 316 L Stainless Steel Prepared by the Selective Laser Melting Method

Effect of Hot Isostatic Pressing on Porosity and Mechanical Properties of 316 L Stainless Steel Prepared by the Selective Laser Melting Method

Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by Electron Beam Melting

Transparent Porous Conductive Substrates for Gas‐Phase Photoelectrochemical Hydrogen Production

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