Selective laser melting of AlSi10Mg: Effects of scan direction, part placement and inert gas flow velocity on tensile strength

An investigation of mechanical properties of Ti6Al4V produced by additive manufacturing (AM) in the as-printed condition have been conducted and compared with wrought alloys. The AM samples were built by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) in 0°, 45° and 90°—relative to horizontal direction. Similarly, the wrought samples were also cut and tested in the same directions relative to the plate rolling direction. The microstructures of the samples were significantly different on all samples. α′ martensite was observed on the SLM, acicular α on EBM and combination of both on the wrought alloy. EBM samples had higher surface roughness (Ra) compared with both SLM and wrought alloy. SLM samples were comparatively harder than wrought alloy and EBM. Tensile strength of the wrought alloy was higher in all directions except for 45°, where SLM samples showed higher strength than both EBM and wrought alloy on that direction. The ductility of the wrought alloy was consistently higher than both SLM and EBM indicated by clear necking feature on the wrought alloy samples. Dimples were observed on all fracture surfaces.

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The Features of Measuring the Gas Flow Velocity in Pipes by an Ultrasonic Correlation Method

Acoustical Physics ◽

10.1134/s1063771021020044 ◽

2021 ◽

Vol 67 (2) ◽

pp. 216-221

Author(s):

A. D. Mansfeld ◽

G. P. Volkov ◽

R. V. Belyaev ◽

A. G. Sanin ◽

P. R. Gromov ◽

...

Keyword(s):

Flow Velocity ◽

Gas Flow ◽

Correlation Method ◽

Gas Flow Velocity

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METHODS OF MAINTAINING THE PROJECT LEVELS OF GAS PRODUCTION AT THE FINAL STAGE OF DEVELOPMENT OF DEPOSITS

Oil and Gas Studies ◽

10.31660/0445-0108-2017-4-80-83 ◽

2017 ◽

pp. 80-83

Author(s):

E. V. Panikarovskii ◽

V. V. Panikarovskii

Keyword(s):

Flow Velocity ◽

Final Stage ◽

Gas Flow ◽

Gas Production ◽

Stage Of Development ◽

Surfactant Solutions ◽

Gas Flow Velocity

In the case of self-kill of wells, the gas flow velocity in the lifting column is not sufficient for carrying to the surface of the liquid, accumulated in the wellbore. To remove liquid from the bottom of wells, solid and liquid surfactants are used. As a result of conducted studies of surfactant compositions, the components of surfactant solutions were chosen to remove liquid from the bottom of wells.

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Effects of Shield Gas Flow on Meltpool Variability and Signature in Scanned Laser Melting

Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation ◽

10.1115/msec2020-8410 ◽

2020 ◽

Author(s):

David C. Deisenroth ◽

Jorge Neira ◽

Jordan Weaver ◽

Ho Yeung

Keyword(s):

Additive Manufacturing ◽

Aspect Ratio ◽

Flow Velocity ◽

Process Monitoring ◽

Gas Flow ◽

Laser Energy ◽

Flow Speed ◽

Powder Bed ◽

Flow Speeds ◽

Gas Flow Velocity

Abstract In laser powder bed fusion metal additive manufacturing, insufficient shield gas flow allows accumulation of condensate and ejecta above the build plane and in the beam path. These process byproducts are associated with beam obstruction, attenuation, and thermal lensing, which then lead to lack of fusion and other defects. Furthermore, lack of gas flow can allow excessive amounts of ejecta to redeposit onto the build surface or powder bed, causing further part defects. The current investigation was a preliminary study on how gas flow velocity and direction affect laser delivery to a bare substrate of Nickel Alloy 625 (IN625) in the National Institute of Standards and Technology (NIST) Additive Manufacturing Metrology Testbed (AMMT). Melt tracks were formed under several gas flow speeds, gas flow directions, and energy densities. The tracks were then cross-sectioned and measured. The melt track aspect ratio and aspect ratio coefficient of variation (CV) were reported as a function of gas flow speed and direction. It was found that a mean gas flow velocity of 6.7 m/s from a nozzle 6.35 mm in diameter was sufficient to reduce meltpool aspect ratio CV to less than 15 %. Real-time inline hotspot area and its CV were evaluated as a process monitoring signature for identifying poor laser delivery due to inadequate gas flow. It was found that inline hotspot size could be used to distinguish between conduction mode and transition mode processes, but became diminishingly sensitive as applied laser energy density increased toward keyhole mode. Increased hotspot size CV (associated with inadequate gas flow) was associated with an increased meltpool aspect ratio CV. Finally, it was found that use of the inline hotspot CV showed a bias toward higher CV values when the laser was scanned nominally toward the gas flow, which indicates that this bias must be considered in order to use hotspot area CV as a process monitoring signature. This study concludes that gas flow speed and direction have important ramifications for both laser delivery and process monitoring.

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Correlation Between Microstructure and Tensile Properties of STS 316L and Inconel 718 Fabricated by Selective Laser Melting (SLM)

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.18792 ◽

2020 ◽

Vol 20 (11) ◽

pp. 6807-6814

Author(s):

Jungsub Lee ◽

Minshik Lee ◽

Im Doo Jung ◽

Jungho Choe ◽

Ji-Hun Yu ◽

...

Keyword(s):

Tensile Strength ◽

Tensile Properties ◽

Selective Laser Melting ◽

Inconel 718 ◽

Tensile Elongation ◽

Processing Condition ◽

Processing Parameters ◽

Fusion Pore ◽

Laser Melting ◽

Track Width

The correlation between microstructure and tensile properties of selective laser melting (SLM) processed STS 316L and Inconel 718 were investigated at various heights (top, middle and bottom) and planes (YZ, ZX and XY). Columnar grains and dendrites were formed by directional growth during solidification. The average melt pool width and depth, and scan track width were similar in both specimens due to fixed processing parameters. SLM Inconel 718 has moderate tensile strength (1165 MPa) and tensile elongation (11.5%), whereas SLM STS 316L has outstanding tensile strength (656 MPa) and tensile elongation (75%) compared to other SLM processed STS 316L. Fine columnar diameter (0.5 μm) and dense microstructures (porosity: 0.35%) in SLM STS 316L promoted the enhancement of tensile elongation by suitable processing condition. Fractographic analysis suggested that the lack of fusion pore with unmelted powder should be avoided to increase tensile properties by controlling processing parameters.

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Research on the Influence of Furnace Structure on Copper Cooling Stave Life

High Temperature Materials and Processes ◽

10.1515/htmp-2017-0040 ◽

2019 ◽

Vol 38 (2019) ◽

pp. 1-7

Author(s):

Feng-guang Li ◽

Jian-liang Zhang

Keyword(s):

Service Life ◽

Flow Velocity ◽

Gas Flow ◽

Flow Distribution ◽

Distribution Model ◽

Variational Structure ◽

Shaft Angle ◽

The Stability ◽

Gas Flow Velocity ◽

Copper Stave

AbstractIn this paper, a blast furnace gas flow distribution model with variable furnace structure was founded based on CFD (computational fluid dynamics) theory, and the gas velocity distribution near the surface of the copper staves in different areas of the BF is calculated under different conditions of variational structure parameters like Bosh angle, shaft angle, and the newly proposed “equivalent Bosh angle.” Based on the calculation, the influence rule of the BF structure on the service life of copper stave and the corresponding operation measures were obtained. The result shows that the increase of the Bosh angle and the decrease of the shaft angle will incur increasing of the gas flow velocity near the surface of the copper staves, which is harmful to the cooling stave life; the variation of the equivalent Bosh angle has a most significant influence on the cooling stave life, and the increase of the equivalent Bosh angle will cause a sharp increase of the gas flow velocity, which will damage the copper staves seriously; adopting long tuyeres and minishing the equivalent Bosh angle will reduce the washing action of the gas flow and ensure the stability of slag hanging to achieve a long service life of copper staves.

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