The influence of laser characteristics on internal flow behaviour in laser melting of metallic substrates

A 316L stainless steel instrument valve body which with complex internal flow passage and used for primary loop flow measurement in pressurized power plant along with test specimen were printed by selective laser melting. The optical metallography of specimen showed the microstructure transform to be uniform after heat treatment state. The residual stress test was tested on three different position on the valve body after heat treatment. The results showed that the valve body mainly had a surface residual compressive stress, and the max main stress was in a range of-367.27MPa to 34.97MPa which get higher along the building direction. Then the application performance of intergranular corrosion test and hydraulic test on the valve body showed a good performance and the result could meet the acceptance requirements of the construction rule.

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Adhesion between Biocomposites and Different Metallic Structures Additive Manufactured

Coatings ◽

10.3390/coatings11040483 ◽

2021 ◽

Vol 11 (4) ◽

pp. 483

Author(s):

Stanca Cuc ◽

Alexandru Burde ◽

Cosmin Cosma ◽

Dan Leordean ◽

Mircea Rusu ◽

...

Keyword(s):

Pure Titanium ◽

Melting Process ◽

Resin Cement ◽

Glass Ionomer ◽

Metallic Surfaces ◽

Laser Melting ◽

Metallic Structures ◽

Metallic Substrates ◽

Morphological Aspects ◽

Resin Modified Glass Ionomer

This study was concerned with the adhesion of resin cement to metal surfaces obtained by selective laser melting process (SLM), and how it could be improved the bond strength at the biocomposite-metal junction. The SLM substrates were manufactured out of pure titanium (Ti), Ti6Al7Nb, and CoCr alloys. The metallic surfaces were covered with 5 types of biocomposites: 2 commercially resin-modified glass-ionomer cements (GC Fuji Plus and KETAC CEM) and 3 types of in-house developed materials. These biocomposites were mechanical characterized under compression and bending trials. The biocomposites-metal adhesion was settled both on as built metallic surfaces and after they were sandblasted with alumina. All the sandblasted SLM surfaces presented higher adhesion strength in comparison with the untreated specimens. The CoCr specimens show the highest bonding value. Additionally, the morphological aspects of joining interfaces were investigated using a scanning electron microscope (SEM). The mechanical properties and metal adhesion of these biocomposites were influenced by the liquid powder ratio. It is essential to apply a surface treatment on SLM substrate to achieve a stronger bond. Also, the chemical composition of biocomposite is a major factor which may improve the adhesion of it on different metallic substrates.

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The Marangoni Convection Effect on Melt Pool Formation during Selective Laser Melting Process

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.412.107 ◽

2021 ◽

Vol 412 ◽

pp. 107-114

Author(s):

Samia Aggoune ◽

Farida Hamadi ◽

Karim Kheloufi ◽

Toufik Tamsaout ◽

El-Hachemi Amara ◽

...

Keyword(s):

Selective Laser Melting ◽

Molten Pool ◽

Marangoni Convection ◽

Flow Behavior ◽

Internal Flow ◽

Melting Process ◽

Heat Diffusion ◽

Maximum Temperature ◽

Laser Melting ◽

Pool Shape

In order to predict the effect of the Marangoni convection and the morphology of melted stainless steel powder, during the selective laser melting (SLM) process, a transient three-dimensional numerical model is developed at the mesoscale. The evolution of the temperature and velocity fields’ is then studied. The initial powder bed distribution is obtained by the discrete element method (DEM) calculation, and the temperature distribution and the molten pool shape deformation are calculated and analyzed by the Ansys-Fluent commercial code. The molten pool shape is obtained by considering the influence of Marangoni convection on the internal flow behavior. The recoil force was not considered in our calculation. As main results, a slight deviation between the position of the maximum temperature of the molten pool and the center of the laser spot is observed. The direction of the heat diffusion is more likely to be horizontal and the flow centrifugal, which causes the melt track to be wide. Finally, the Marangoni convection is the main driver of the flow.

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Revealing internal flow behaviour in arc welding and additive manufacturing of metals

Nature Communications ◽

10.1038/s41467-018-07900-9 ◽

2018 ◽

Vol 9 (1) ◽

Cited By ~ 40

Author(s):

Lee Aucott ◽

Hongbiao Dong ◽

Wajira Mirihanage ◽

Robert Atwood ◽

Anton Kidess ◽

...

Keyword(s):

Additive Manufacturing ◽

Arc Welding ◽

Internal Flow ◽

Flow Behaviour

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Flow Behavior and Microstructure Evolution of Ti-6Al-4V Titanium Alloy Produced by Selective Laser Melting Compared to Wrought

10.21203/rs.3.rs-293851/v1 ◽

2021 ◽

Author(s):

Denis R Salikhyanov ◽

Valeriya E Veselova ◽

Vladimir P Volkov

Keyword(s):

Mechanical Properties ◽

Titanium Alloy ◽

Selective Laser Melting ◽

Microstructure Evolution ◽

Flow Behavior ◽

Flow Behaviour ◽

Laser Melting ◽

Manufacturing Method ◽

Conventional Technology ◽

Cylindrical Samples

Abstract Nowadays, selective laser melting (SLM) represents an option for manufacturing parts from titanium alloys, especially from Ti-6Al-4V alloy. However, mechanical properties of parts made of Ti-6Al-4V such as ductility and fatigue resistance are significantly lower than that for conventional manufactured parts. One of the promising ways to improve mechanical properties of SLM parts can be the use of deformation post-processing, for example, combining SLM with subsequent die forging. Therefore, the aim of the present study is to investigate the rheological properties and microstructure evolution of Ti-6Al-4V titanium alloy fabricated by SLM under temperatures of cold and hot deformation. The tests of cylindrical samples made of Ti-6Al-4V alloy was performed using a plastometer in the temperature range of 20–1200 °C, at strain rate ξ of 1 s− 1 up to strain e of 0.85. To evaluate the effect of manufacturing method of samples on flow behaviour and microstructure evolution of the material, the samples made of Ti-6Al-4V alloy fabricated by conventional technology were tested under the same conditions. The differences in the flow behaviour of SLM and conventional manufactured samples from Ti-6Al-4V which were significant at test temperatures of 20–900 °С were analysed and explained. In contrast to conventional manufactured parts, SLM-produced Ti-6Al-4V reveal higher peak stresses in the flow curves and temperature sensitivity of flow stresses. This in turn leads to high inhomogeneity of deformation of SLM-produced parts.

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Electron microscopy studies of plasma-sprayed materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074276 ◽

1983 ◽

Vol 41 ◽

pp. 70-71

Author(s):

K.R. Subramanian ◽

A.H. King ◽

H. Herman

Keyword(s):

Plasma Spraying ◽

Substrate Surface ◽

Flame Temperature ◽

Ceramic Coatings ◽

Metallic Substrates ◽

Hot Plasma ◽

Almost All ◽

Plasma Sprayed ◽

Hostile Environments ◽

Plasma Spraying Process

Plasma spraying is a technique which is used to apply coatings to metallic substrates for a variety of purposes, including hardfacing, corrosion resistance and thermal barrier applications. Almost all of the applications of this somewhat esoteric fabrication technique involve materials in hostile environments and the integrity of the coatings is of paramount importance: the effects of process variables on such properties as adhesive strength, cohesive strength and hardness of the substrate/coating system, however, are poorly understood.Briefly, the plasma spraying process involves forming a hot plasma jet with a maximum flame temperature of approximately 20,000K and a gas velocity of about 40m/s. Into this jet the coating material is injected, in powder form, so it is heated and projected at the substrate surface. Relatively thick metallic or ceramic coatings may be speedily built up using this technique.

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Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104972 ◽

1988 ◽

Vol 46 ◽

pp. 582-583

Author(s):

C. J. Chan ◽

K. R. Venkatachari ◽

W. M. Kriven ◽

J. F. Young

Keyword(s):

Particle Size ◽

Raw Materials ◽

Shape Change ◽

Microstructural Characterization ◽

Particle Size Effect ◽

Dicalcium Silicate ◽

Laser Melting ◽

Uniform Size ◽

Cell Shape Change ◽

Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

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Investigation of the natural ventilation of wind catchers with different geometries in arid region houses

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.14.3.2020.12.0557 ◽

2020 ◽

Vol 14 (3) ◽

pp. 7109-7124

Author(s):

Nasreddine Sakhri ◽

Younes Menni ◽

Houari Ameur ◽

Ali J. Chamkha ◽

Noureddine Kaid ◽

...

Keyword(s):

Arid Region ◽

Natural Ventilation ◽

Reduction Rate ◽

Internal Flow ◽

Climatic Conditions ◽

Maximum Pressure ◽

Ventilation Technique ◽

Window Position ◽

The One ◽

Flow Velocities

The wind catcher or wind tower is a natural ventilation technique that has been employed in the Middle East region and still until nowadays. The present paper aims to study the effect of the one-sided position of a wind catcher device against the ventilated space or building geometry and its natural ventilation performance. Four models based on the traditional design of a one-sided wind catcher are studied and compared. The study is achieved under the climatic conditions of the South-west of Algeria (arid region). The obtained results showed that the front and Takhtabush’s models were able to create the maximum pressure difference (ΔP) between the windward and leeward of the tower-house system. Internal airflow velocities increased with the increase of wind speed in all studied models. For example, at Vwind = 2 m/s, the internal flow velocities were 1.7, 1.8, 1.3, and 2.5 m/s for model 1, 2, 3, and 4, respectively. However, at Vwind = 6 m/s, the internal flow velocities were 5.6, 5.5, 2.5, and 7 m/s for model 1, 2, 3, and 4, respectively. The higher internal airflow velocities are given by Takhtabush, traditional, front and middle tower models, respectively, with a reduction rate between the tower outlet and occupied space by 72, 42, 36, and 33% for the middle tower, Takhtabush, traditional tower, and the front model tower, respectively. This reduction is due to the due to internal flow resistance. The third part of the study investigates the effect of window (exist opening) position on the opposite wall. The upper, middle and lower window positions are studied and compared. The air stagnation or recirculation zone inside the ventilated space reduced from 55% with the lower window to 46% for the middle window and reached 35% for the upper window position. The Front and Takhtabush models for the one-sided wind catcher with an upper window position are highly recommended for the wind-driven natural ventilation in residential houses that are located in arid regions.

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Experimental and Numerical Analysis of a Motorcycle Air Intake System Aerodynamics and Performance

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.1.2020.10.0565 ◽

2020 ◽

Vol 17 (1) ◽

Author(s):

M. A. Abd Halim ◽

N. A. R. Nik Mohd ◽

M. N. Mohd Nasir ◽

M. N. Dahalan

Keyword(s):

Combustion Process ◽

Three Dimensional ◽

Engine Performance ◽

Internal Flow ◽

Rapid Expansion ◽

Navier Stokes ◽

Turbulent Fluctuation ◽

Ansys Fluent ◽

Induction System ◽

Acceleration And Deceleration

Induction system or also known as the breathing system is a sub-component of the internal combustion system that supplies clean air for the combustion process. A good design of the induction system would be able to supply the air with adequate pressure, temperature and density for the combustion process to optimizing the engine performance. The induction system has an internal flow problem with a geometry that has rapid expansion or diverging and converging sections that may lead to sudden acceleration and deceleration of flow, flow separation and cause excessive turbulent fluctuation in the system. The aerodynamic performance of these induction systems influences the pressure drop effect and thus the engine performance. Therefore, in this work, the aerodynamics of motorcycle induction systems is to be investigated for a range of Cubic Feet per Minute (CFM). A three-dimensional simulation of the flow inside a generic 4-stroke motorcycle airbox were done using Reynolds-Averaged Navier Stokes (RANS) Computational Fluid Dynamics (CFD) solver in ANSYS Fluent version 11. The simulation results are validated by an experimental study performed using a flow bench. The study shows that the difference of the validation is 1.54% in average at the total pressure outlet. A potential improvement to the system have been observed and can be done to suit motorsports applications.

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