scholarly journals Effects of Powder Feed Rate on Formation of Fully Equiaxed β Grains in Titanium Alloys Fabricated by Directed Energy Deposition

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 521 ◽  
Author(s):  
Qiang Zhang ◽  
Siyu Zhang ◽  
Min Zheng ◽  
Yongchao Ou ◽  
Shang Sui ◽  
...  
Keyword(s):  
Feed Rate ◽  
Molten Pool ◽  
Cellular Structure ◽  
Energy Deposition ◽  
Grain Morphology ◽  
Thermal Conditions ◽  
Powder Feed Rate ◽  
Powder Feed ◽  
Directed Energy Deposition ◽  
Directed Energy

A near β titanium alloy, Ti5Al2Sn2Zr4Mo4Cr, was fabricated by directed energy deposition (DED) with different powder feed rates to investigate the formation of fully equiaxed β grains. A two-dimensional numerical model was developed to investigate the thermal conditions of the molten pool. Experimental results showed that the formation of an epitaxial cellular structure at the bottom of the molten pool is almost unavoidable. An increase in the powder feed rate produces a moderate thermal condition and promotes the formation of equiaxed grains in a single cladding layer. However, it could not guarantee the formation of a fully equiaxed microstructure in a block sample. From a low to high powder feed rate, fully columnar, mixed equiaxed–columnar, and fully equiaxed microstructures were obtained. Grain morphology was also affected by the remolten process. Increasing the powder feed rate reduced the remolten depth and broke the continuity of the epitaxial cellular structure, leading to different grain morphologies.

Effect of Process Parameters on Laser Directed Energy Deposition of Copper

2019 ◽  
Author(s):  
Sunil Yadav ◽  
Christ P. Paul ◽  
Arackal N. Jinoop ◽  
Saurav K. Nayak ◽  
Arun K. Rai ◽  
...  
Keyword(s):  
Process Parameters ◽  
Feed Rate ◽  
Laser Power ◽  
Energy Deposition ◽  
Process Conditions ◽  
Powder Feed Rate ◽  
Track Geometry ◽  
Powder Feed ◽  
Directed Energy Deposition ◽  
Directed Energy

Abstract Laser Additive Manufacturing (LAM) is an advanced manufacturing processes for fabricating engineering components directly from CAD Model by depositing material in a layer by layer fashion using lasers. LAM is being widely deployed in various sectors such as power, aerospace, automotive etc. for fabricating complex shaped and customized components. One of the most commonly used LAM process is Directed Energy Deposition (LAM-DED) which is used for manufacturing near net shaped components with tailored microstructure, multi-materials (direct and graded) and complex geometry. This paper reports experimental investigation of LAM of Copper (Cu) tracks on Stainless Steel 304 L (SS 304L) using an indigenously developed LAM-DED system. Cu-SS304L joints find wider applications in tooling, automotive and aerospace sectors due to its combination of higher strength, thermal conductivity and corrosion resistance. However, laying Cu layers on SS304L is not trivial due to large difference in the thermo-physical properties. Thus, a comprehensive experiments using full factorial design are carried out and a number of Cu tracks were laid on SS304L substrate by varying laser power, scan speed and powder feed rate. The laid tracks are characterized for track geometry and porosity and the quality of the tracks are analyzed. Lower values of laser power and higher powder feed rate results in discontinuous deposition, while higher laser power and lower powder feed rate results in cracked deposits. Porosity is observed to vary from 6–45 % at different process conditions. Analysis of Variance (ANOVA) of deposition rate and track geometry is performed to estimate the major contributing process parameters. This study paves a way to understand effect of process parameters on LAM-DED for fabricating bimetallic joints and graded structures of Copper and SS304L.

Parametric investigation and characterization on SS316 built by laser-assisted directed energy deposition

2019 ◽  
Vol 234 (3) ◽  
pp. 452-466 ◽  
Author(s):  
K Benarji ◽  
Y Ravi Kumar ◽  
CP Paul ◽  
AN Jinoop ◽  
KS Bindra
Keyword(s):  
Deposition Rate ◽  
Process Parameters ◽  
Feed Rate ◽  
Laser Power ◽  
Energy Deposition ◽  
Scanning Speed ◽  
Powder Feed Rate ◽  
Parametric Investigation ◽  
Powder Feed ◽  
Directed Energy

In the present work, parametric investigation and characterization of stainless steel 316 (SS316) built by laser-assisted directed energy deposition (L-DED) is performed. Single-track L-DED experiments are carried by varying laser power, scanning speed, and powder feed rate using full factorial experimental design. The effect of L-DED process parameters on the track geometry, deposition rate, and microhardness is investigated, and three different combinations of process parameters yielding maximum deposition rate and hardness are identified for bulk investigation. The identified process parameters are laser power of 1000 W, powder feed rate of 8 g/min, and scanning speed of 0.4 m/min, 0.5 m/min, and 0.6 m/min. The austenitic phase [Formula: see text] is detected at all the conditions. However, ferrite [Formula: see text] peak is observed at 0.6 m/min due to microsegregation and thermal gradients. The minimum crystallite size is estimated to be 24.88 nm at 0.6 m/min. The porosity and microstructure analysis is carried out by optical microscopic images. The fine columnar dendritic structure is observed in L-DED samples at all conditions. An average microhardness of 317.4 HV0.98 N is obtained at 0.4 m/min, and it is observed that microhardness reduces with an increase in scanning speed mainly due to increase in lack of fusion and porosity. Tribology studies are carried out at different values of normal load and sliding velocity. The minimum specific wear rate of 0.02497 × 10−4 mm3/Nm is observed at scanning speed of 0.4 m/min. Scanning electron microscope of the wear tracks analysis shows abrasive wear as the major wear mechanism. This study provides a path for building SS316 components for various engineering applications.

Modeling of Transport Phenomena in the Laser Multilayered Cladding

2009 ◽  
Author(s):  
Fanrong Kong ◽  
Radovan Kovacevic
Keyword(s):  
Feed Rate ◽  
Molten Pool ◽  
Laser Power ◽  
Steel Powder ◽  
Mass Transfer Process ◽  
Scanning Speed ◽  
Heat Radiation ◽  
Powder Feed Rate ◽  
Transient Model ◽  
Powder Feed

The present work studies the heat and mass transfer process in the laser multilayered cladding of H13 tool steel powder by numerical modeling and experimental validation. A solid-liquid-gas unified transient model was developed to investigate the evolution of temperature distribution and flow velocity of the liquid phase in the molten pool. In this model, an enthalpy-porosity approach was applied to deal with the solidification and melting occurring in the clad, and a level-set method was used to track the evolution of the molten pool free surface. Moreover, heat loss due to forced convection and heat radiation and laser heat input occurring on the top surface of deposited layer and substrate have been incorporated into the source term of governing equations. The effects of laser power, scanning speed, and powder feed rate on the dilution and height of the multilayered clad are investigated based on the numerical model and experimental measurement. The results show that increasing the laser power and powder feed rate, or reducing the scanning speed, can increase the clad height and directly influence the remelted depth of each layer of deposition. The numerical results have a qualitative agreement with the experimental measurements.

scholarly journals Molten pool characteristics of a nickel-titanium shape memory alloy for directed energy deposition

2021 ◽  
Vol 142 ◽  
pp. 107215
Author(s):  
Shiming Gao ◽  
Yuncong Feng ◽  
Jianjian Wang ◽  
Mian Qin ◽  
Ojo Philip Bodunde ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Molten Pool ◽  
Energy Deposition ◽  
Nickel Titanium ◽  
Directed Energy Deposition ◽  
Directed Energy

scholarly journals State of the Art in Directed Energy Deposition: From Additive Manufacturing to Materials Design

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 418 ◽  
Author(s):  
Adrita Dass ◽  
Atieh Moridi
Keyword(s):  
Additive Manufacturing ◽  
High Performance ◽  
Energy Deposition ◽  
Future Research ◽  
New Paradigm ◽  
Process Map ◽  
Powder Feed ◽  
Directed Energy Deposition ◽  
Aerospace Medical ◽  
Directed Energy

Additive manufacturing (AM) is a new paradigm for the design and production of high-performance components for aerospace, medical, energy, and automotive applications. This review will exclusively cover directed energy deposition (DED)-AM, with a focus on the deposition of powder-feed based metal and alloy systems. This paper provides a comprehensive review on the classification of DED systems, process variables, process physics, modelling efforts, common defects, mechanical properties of DED parts, and quality control methods. To provide a practical framework to print different materials using DED, a process map using the linear heat input and powder feed rate as variables is constructed. Based on the process map, three different areas that are not optimized for DED are identified. These areas correspond to the formation of a lack of fusion, keyholing, and mixed mode porosity in the printed parts. In the final part of the paper, emerging applications of DED from repairing damaged parts to bulk combinatorial alloys design are discussed. This paper concludes with recommendations for future research in order to transform the technology from “form” to “function,” which can provide significant potential benefits to different industries.

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