Wyniki wyszukiwania - BazTech

1

Numerical modelling of SS316L powder flowability for laser powder-bed fusion

Bouabbou A., Vaudreuil S.

Archives of Materials Science and Engineering

|

2023

|

Vol. 120, nr 1

22--29

EN

Purpose: This work aims to improve the powder-bed spreading process for laser powder bed fusion additive manufacturing by gaining a greater understanding of metal powder flowability through numerical modelling and in-situ experimentation. Design/methodology/approach: Using the Discrete Element Method (DEM) to study the flowability of the powder and its intrinsic properties. A high-fidelity particle-scale model was developed to capture the dynamics of metal particle interactions in a virtual Hall flow meter based on a modified Beverloo law. The results are validated experimentally using the Hall flow static powder characterisation technique. Findings: For SS316L powder alloy with the hall-value of 29s/50g and with an angle of repose (AOR) of 32°, the modelled powder that exhibited the same flow behaviour was found using 0.5 for both rolling and sliding coefficients resulting in simulated Hall value of 28.55s/50g with a simulated flow rate of 0.571 g/s, which is validated by AOR of the simulated powder [31.2°- 32.6°]. However, rolling friction had minimal effect on the mass flow rate but increased the angle of repose. Sliding friction significantly decreased the mass flow rate and increased AOR. Research limitations/implications: DEM is an ideal method to study flowability. However, there are certain constraints imposed on the computational power by a number of simulated particles and simulation time-step. Future research may involve investigating other dynamic flowability characterisation techniques. Practical implications: Enabling a better understanding of powder particle flow at a micro-scale by modelling powder flowability. This leads to simulating a more realistic powder bed and improving the powder spreading process, leading to better AM parts quality. Originality/value: This paper provides a unique approach for modelling the flowability of SS316L powder using a Beverloo law-based design of the Hall flow meter. This will improve the modelling of the spreading process needed for metal 3D printing.

2

Rapid manufacture of high performance materials by LENS®

Hedges M.

Problemy Eksploatacji

|

2005

|

nr 2

21--30

EN

Laser Engineered Net Shaping (LENS®) is an additive manufacturing technique for rapidly fabricating, enhancing and repairing metal components directly from CAD data. The process creates fully functional parts, using a wide array of metal powder feedstock including titanium, nickel, cobalt, steel alloys and novel materials such as MMCs and Functionally Gradient Materials. The process is used in medical implant, aerospace, defence and motor sport markets. This paper will review the State of the Art for the technology and present application case studies. Particular focus of the paper will be on material quality and the time, cost and quality benefits obtained in industrial applications.

PL

Laserowe modelowanie siatkowe (LENS®) stanowi dodatkową technikę wytwarzania wykorzystywaną w celu szybkiej produkcji, poprawy jakości i naprawy części metalowych bezpośrednio z danych CAD. Proces ten umożliwia tworzenie w pełni funkcjonalnych części z wykorzystaniem różnego typu podawanych proszków metalowych, w tym tytanu, niklu, kobaltu, stopów stali oraz nowych materiałów, takich jak kompozyty metalowe oraz funkcjonalne materiały gradientowe. Proces ten znajduje zastosowanie w odniesieniu do implantów medycznych, lotnictwa, przemysłu obronnego oraz sportów motoryzacyjnych. Artykuł prezentuje obecny stan wiedzy na temat technologii oraz przykłady jej zastosowania. Szczególna uwaga skoncentrowana jest na właściwościach materiałów, czasie, kosztach oraz jakości uzyskanych w zastosowaniach przemysłowych.

3

Structural studies of carbon steel powders subjected to ball milling

Oleszak D., Janczewski A., Kulik T., Grabias A.

Inżynieria Materiałowa

|

2004

|

R. XXV, nr 3

536-539

EN

The structural and phase transformations in carbon steel powders subjected to ball milling were studied. Optical microscopy observations showed that the mean size of the milled powders was below 10 žm. The ball milling process of two different carbon steel powders, containing 0.1 and 1.1 % C, led to the dissolution of cementite and formation of nanoferrite, characterized by crystallite size and lattice strain of about 10 nm and 0.5%, respectively. There was no significant difference in the behaviour of these two steel powders subjected to ball milling. For high carbon steel (1.1 % C) Mössbauer spectroscopy revealed the formation of highly distorted ferrite with residual 3% of Fe3C after 100 h of processing. DSC studies showed one exothermic effect attributed to the decrease of lattice strain and increase of crystallite size and one endothermic effect associated probably with cementite precipitation.

PL

Zbadano przemiany strukturalne i fazowe w proszkach stali węglowych poddanych mieleniu w młynku kulowym. Obserwacje przeprowadzone w mikroskopie optycznym wykazały, że średni rozmiar cząstek proszku wynosił po mieleniu poniżej 10 mikrometrów. Proces mielenia proszków stali zawierających 0.1 i 1.1 % C prowadził do rozpadu cementytu i tworzenia się nanoferrytu charakteryzującego się średnimi rozmiarami krystalitów ok. 10 nm i odkształceniami sieciowymi rzędu 0.5%. W przypadku stali wysokowęglowej badania mossbauerowskie wykazały obecność w strukturze po 100 h mielenia odkształconego ferrytu, z 3% pozostałością cementytu. Badania kalorymetyryczne ujawniły efekt egzotermiczny przypisany zanikowi odkształceń sieciowych i rozrostowi krystalitów oraz efekt endotermiczny związany prawdopodobnie z wydzielaniem się cementytu.

4

Reactive antireflective coatings for laser treatment of steels.

Przybyłowicz K., Przybyłowicz J., Kusiński J.

Inżynieria Materiałowa

|

1998

|

R. XIX, nr 4

1047-1050

EN

In the paper experiments have been performed to find out composition of the coatings producing exothermic reaction in them under the influence of laser beam counteracting the change of steel composition and radiation of heat. The coatings are based on iron oxides mixed with carbon or metal powders of high reductive properties (silicon, magnesium, aluminium). The results have shown, that the coatings ensured high conductivity and absorptivity of heat and in many cases their neutral behaviour on heated surface has been stated.

5

Multilayer laser cladding of bronze powder for fast prototyping.

Jendrzejewski R., Śliwiński G.

Inżynieria Materiałowa

|

1998

|

R. XIX, nr 4

1100-1103

EN

Process parameters of the multilayer laser cladding of the bronze B10 alloy powder are experimentally investigated. The 3-D structures are prepared trace-on-trace by remelting of the powder injected into the processing zone through a nozzle. An efficient formation of the volumetric structures of controlled geometry is observed. Microanalysis of the samples confirm the expected mechanical properties, low porosity and the highly homogeneous structure of the multilayers. For the subsequent clads of 1 mm width and 0,6 mm in height produced at velocities of 1m/min. the process efficiency of about 5% is obtained.