Volumetric energy density impact on mechanical properties of additively manufactured 718 Ni alloy

Stegman, Benjamin; Shang, Anyu; Hoppenrath, Luke; Raj, Anant; Abdel-Khalik, Hany S.; Sutherland, John W.; Schick, David; Morgan, Victor; Jackson, Kirti; Zhang, Xinghang

doi:10.1016/j.msea.2022.143699

Cited by 15 publications

(4 citation statements)

References 43 publications

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“…Within these grains are dislocation cellular walls observed in our previous work, which act as soft barriers to dislocation motion. They have a minor effect on the overall n in comparison to hard barriers like precipitates or grain boundaries, but are unique to LPBF materials and, therefore, the added work hardening ability from larger grains becomes more apparent [29,37,38]. The last aspect that can affect the overall deformation behavior and work hardening of the material as it plastically deforms is the grain boundary characteristics.…”

Section: Discussionmentioning

confidence: 99%

“…Both PSDs were printed on an EOS M290 with the five parameter sets detailed in Table 1. Based on previous work with volumetric energy density, these parameters were chosen to test the extreme upper and lower bounds with a heightened emphasis on the near-optimal region of 67.5 J/mm 3 [29,30]. The nominal parameter set (C) has a laser power, scanning speed, hatch spacing and layer thickness of 285 W, 960 mm/s, 110 µm and 40 µm.…”

Section: Methodsmentioning

confidence: 99%

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The Influence of Powder Particle Size Distributions on Mechanical Properties of Alloy 718 by Laser Powder Bed Fusion

Stegman,

Lopez,

Jarosinski

et al. 2023

Metals

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Currently, metallic powders for laser powder bed fusion (LPBF) primarily come in two commercially available powder size distributions (PSDs): 15+/45− for non-reactive powders and 15+/63− for reactive powders. These powders are generally produced via gas atomization processes that create highly spherical particles with a Gaussian PSD. Because of the standard deviation within a Gaussian distribution, only small portions of the total product are used for LPBF applications. This screening process makes the other particle sizes a waste product and, thus, increases processing costs. The non-reactive 718 powder was printed with both the typical PSD of 15+/45− and a wider bimodal experimental PSD. Compared to conventional 718, the 718 alloys with bimodal PSD shows less than a 0.2% difference in density, and insignificant change in mechanical behavior. Electron backscattered diffraction studies revealed that grain sizes and morphology were similar between the two sample sets, but bimodal 718 alloy has a slightly greater degree of large grains. The study suggests that particles with wide or bimodal size distributions show promise in producing equivalent high-quality products without sacrificing mechanical properties.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The Influence of Powder Particle Size Distributions on Mechanical Properties of Alloy 718 by Laser Powder Bed Fusion

Stegman,

Lopez,

Jarosinski

et al. 2023

Metals

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“…Inconel 718 (IN718) is an austenitic Ni–Cr–Fe superalloy with excellent mechanical properties, especially at high temperatures of 650 °C. 1,2 Fabricating high-strength materials, like IN718 superalloys, has always been challenging. Adopting additive manufacturing (AM) technology has facilitated the production of complex-shaped intricate superalloys.…”

Section: Introductionmentioning

confidence: 99%

Role of laser power and scan speed combination on the surface quality of additive manufactured nickel-based superalloy

Praveenkumar,

Raja,

Jamadon

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part L:

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In laser-based powder bed fusion (L-PBF), the volumetric energy density (VED) controlled by laser power (LP) and scan speed (SS) significantly affects the desired surface quality. Any variations in the LP and SS on the VED notably affect the surface quality due to changes in laser powder interactions. Therefore, the present study concentrated on the effect of various combinations of LP and SS, i.e. low LP (160 W) with high SS (1250 mm/s), high LP (320 W) with low SS (410 mm/s), low LP (160 W) with low SS (550 mm/s) and high LP (320 W) with high SS (1100 mm/s). The wide range of varying VEDs was chosen between 29 and 177 J/mm3. The results showed the VED range between 66 and 90 J/mm3 exhibited minimum surface roughness parameters of 0.51 < Ra < 0.52 µm, 0.63 < Rq < 0.64 µm, and 2.53 < Rz < 2.79 µm. The specific impact of LP and SS combination between 160 and 320 W with 400–1250 mm/s by maintaining a constant VED of 66 J/mm3 was also investigated. At a constant VED of 66 J/mm3, the combination of 280 W and 960 mm/s shows minimum roughness parameters of Ra = 0.527 µm, Rq = 0.645 µm, and Rz = 2.446 µm. The results showed that the combination of low LP with low SS, high LP with high SS, low LP with high SS, and high LP with low SS, increases surface roughness.

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“…So, what is theoretically expected is a variation of the material's printability window (Figure 2 [18,[45][46][47]) working in these particular thermal conditions. Since the process is essentially thermally driven, the difference in thermal history between layer parts or from layer to layer could affect the mechanical properties and microstructure [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. According to Williams et al [21], this phenomenon has not been extensively studied in the literature for the L-PBF process; only a few studies have been performed for the Ti-6Al-4V alloy [39,40].…”

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confidence: 99%

Study on the Effect of Inter-Layer Cooling Time on Porosity and Melt Pool in Inconel 718 Components Processed by Laser Powder Bed Fusion

Baldi

Giorgetti

Palladino³

et al. 2023

Materials

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This paper investigates the effects on the material microstructure of varying the Inter-Layer Cooling Time (ILCT) during the printing process in laser powder bed fusion (L-PBF) multi-laser machines. Despite these machines allowing higher productivity rates compared to single laser machines, they are affected by lower ILCT values, which could be critical for material printability and microstructure. The ILCT values depend both on the process parameter sets and design choices for the parts and play an important role in the Design for Additive Manufacturing approach in L-PBF process. In order to identify the critical range of ILCT for this working condition, an experimental campaign is presented on the nickel-based superalloy Inconel 718, which is widely used for the printing of turbomachinery components. The effect of ILCT on the microstructure of the material is evaluated in terms of porosity and melt pool analysis on printed cylinder specimens, considering ILCT decreasing and increasing in the range of 22 to 2 s. The experimental campaign shows that an ILCT of less than 6 s introduces criticality in the material microstructure. In particular, at an ILCT value of 2 s, widespread keyhole porosity (close to 1‰) and critical and deeper melt pool (about 200 microns depth) are measured. This variation in melt pool shape indicates a change in the powder melting regime and, consequently, modifications of the printability window promoting the expansion of the keyhole region. In addition, specimens with geometry obstructing the heat flow have been studied using the critical ILCT value (2 s) to evaluate the effect of the surface-to-volume ratio. The results show an enhancement of the porosity value (about 3‰), while this effect is limited for the depth of the melt pool.

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Volumetric energy density impact on mechanical properties of additively manufactured 718 Ni alloy

Cited by 15 publications

References 43 publications

The Influence of Powder Particle Size Distributions on Mechanical Properties of Alloy 718 by Laser Powder Bed Fusion

The Influence of Powder Particle Size Distributions on Mechanical Properties of Alloy 718 by Laser Powder Bed Fusion

Role of laser power and scan speed combination on the surface quality of additive manufactured nickel-based superalloy

Study on the Effect of Inter-Layer Cooling Time on Porosity and Melt Pool in Inconel 718 Components Processed by Laser Powder Bed Fusion

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