Study of Powder Gas Entrapment and Its Effects on Porosity in 17-4 PH Stainless Steel Parts Fabricated in Laser Powder Bed Fusion

Basu, Debomita; Meyer, John L. L.; Larson, Elizabeth; Kuo, Robin; Beuth, Jack; Rollett, Anthony D.

doi:10.1007/s11837-020-04491-z

Cited by 12 publications

(5 citation statements)

References 34 publications

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“…These microhardness measurements and tensile results confirm that this bimodal PSD samples are statistically similar in the AP state, in comparison to the unimodal control 718, but some differences can be observed. The density measurements and fracture surfaces reveal that there are similar levels of measured porosity, likely caused by gasses dissolved or trapped in the powder feedstock [31,32]. Given these materials were processed with similar parameters and based on our previous work, the fracture surface and tensile results confirm a similar deformation mechanism [28].…”

Section: Discussionmentioning

confidence: 52%

“…Next, 10 mm × 10 mm × 10 mm cubes were printed for microstructural characterization, and plates with dimensions of 50 × 10 × 2 mm were used to fabricate tensile samples. Archimedes' density measurements were conducted on the cubes, using the theoretical density value of 8.193 g/cm 3 for IN718 [31]. Scanning electron microscopy (SEM) micrographs were collected on a Thermo Fisher Quanta Field Emission Gun (FEG) 650 SEM microscope.…”

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: 52%

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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“…In the realm of metal printing technologies, prominent examples include laser metal fusion (LMF), selective laser melting (SLM), and direct metal laser sintering (DMLS) [24,25]. These methodologies have undergone extensive investigation to elucidate their impact on material performance, considering factors such as porosity [26], process parameters, building atmosphere, post-heat treatments, and initial powder characteristics. These investigations have focused on phase transformation, microcrack formation, microstructure evolution, and mechanical properties, particularly in stainless steel materials [27][28][29].…”

Section: Of 17mentioning

confidence: 99%

Characterization of Microstructural and Mechanical Properties of 17-4 PH Stainless Steel by Cold Rolled and Machining vs. DMLS Additive Manufacturing

Moreno-Garibaldi,

Alvarez-Vera,

Beltrán-Fernández

et al. 2024

JMMP

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The 17-4 PH stainless steel is widely used in the aerospace, petrochemical, chemical, food, and general metallurgical industries. The present study was conducted to analyze the mechanical properties of two types of 17-4 PH stainless steel—commercial cold-rolled and direct metal laser sintering (DMLS) manufactured. This study employed linear and nonlinear tensile FEM simulations, combined with various materials characterization techniques such as tensile testing and nanoindentation. Moreover, microstructural analysis was performed using metallographic techniques, optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results on the microstructure for 17-4 PH DMLS stainless steel reveal the layers of melting due to the laser process characterized by complex directional columnar structures parallel to the DMLS build direction. The mechanical properties obtained from the simple tension test decreased by 17% for the elastic modulus, 7.8% for the yield strength, and 7% for the ultimate strength for 17-4 PH DMLS compared with rolled 17-4 PH stainless steel. The FEM simulation using the experimental tension test data revealed that the 17-4 PH DMLS stainless steel experienced a decrease in the yield strength of ~8% and in the ultimate strength of ~11%. A reduction of the yield strength of the material was obtained as the grain size increased.

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“…There has been a growing interest in "gas entrapment" during metal additive manufacturing in terms of residual porosity, but not for the production of porous metals (e.g., refs. [29,30]). The initial pore size of the spheres is quite small, often being submicron (e.g., see Figure 4), while the Kearns process [31] used in Ti starts with pores after HIP that are several microns to 10s of microns across.…”

Section: Gas Entrapmentmentioning

confidence: 99%

Hybrid Pore Formation in Copper Spheres by Gas Entrapment and Oxide Reduction

Jones,

Tse Lop Kun,

Patterson

et al. 2023

Adv Eng Mater

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Solid‐state methods for producing porous metals vary greatly in their approaches and outcomes, and they often result in distinctly different pore sizes and/or characteristics. By combining methods in a hybrid process, it is possible that unique porous structures can be made that are simpler to produce, have improved functional properties, or are otherwise superior to any single approach. For the first time, a combination of gas entrapment and oxide reduction to produce microscale porosity in millimeter‐scale copper spheres created by planetary milling is reported. The milling process entraps Ar in micron to submicron pores within the spheres, which are comprised of a Cu 2 mol% CuO metal matrix composite. Upon heating at 800 °C in an inert atmosphere, the individual spheres expand and form ≈29% closed porosity with an average pore size of 1.5 μm. When those spheres are then reheated to 600 °C in a reducing atmosphere, the porosity is converted to being almost entirely open with an average size of 2.3 μm. In addition to the unique nature of the porosity, the processing of the spheres is unusual in that it is completed after only 90 min of milling.

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Study of Powder Gas Entrapment and Its Effects on Porosity in 17-4 PH Stainless Steel Parts Fabricated in Laser Powder Bed Fusion

Cited by 12 publications

References 34 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

Characterization of Microstructural and Mechanical Properties of 17-4 PH Stainless Steel by Cold Rolled and Machining vs. DMLS Additive Manufacturing

Hybrid Pore Formation in Copper Spheres by Gas Entrapment and Oxide Reduction

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