scholarly journals Correction to: Characterization and Optimization of Process Parameters for Directed Energy Deposition Powder-Fed Laser System

Author(s):  
Daniel Andres Rojas Perilla ◽  
Johan Grass Nuñez ◽  
German Alberto Barragan De Los Rios ◽  
Fabio Edson Mariani ◽  
Reginaldo Teixeira Coelho
Author(s):  
Gabriele Piscopo ◽  
Alessandro Salmi ◽  
Eleonora Atzeni

AbstractThe production of large components is one of the most powerful applications of laser powder-directed energy deposition (LP-DED) processes. High productivity could be achieved, when focusing on industrial applications, by selecting the proper process parameters. However, it is of crucial importance to understand the strategies that are necessary to increase productivity while maintaining the overall part quality and minimizing the need for post-processing. In this paper, an analysis of the dimensional deviations, surface roughness and subsurface residual stresses of samples produced by LP-DED is described as a function of the applied energy input. The aim of this work is to analyze the effects of high-productivity process parameters on the surface quality and the mechanical characteristics of the samples. The obtained results show that the analyzed process parameters affect the dimensional deviations and the residual stresses, but have a very little influence on surface roughness, which is instead dominated by the presence of unmelted particles.


2020 ◽  
Vol 26 ◽  
pp. 1108-1112 ◽  
Author(s):  
B.N. Manjunath ◽  
A.R. Vinod ◽  
K. Abhinav ◽  
S.K. Verma ◽  
M. Ravi Sankar

Author(s):  
Sunil Yadav ◽  
Christ P. Paul ◽  
Arackal N. Jinoop ◽  
Saurav K. Nayak ◽  
Arun K. Rai ◽  
...  

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.


Author(s):  
Alessandro Carrozza ◽  
Federico Mazzucato ◽  
Alberta Aversa ◽  
Mariangela Lombardi ◽  
Federica Bondioli ◽  
...  

Abstract Directed energy deposition is an additive manufacturing technology which usually relies on prototype machines or hybrid systems, assembled with parts from different producers. Because of this lack of standardization, the optimization of the process parameters is often a mandatory step in order to develop an efficient building process. Although, this preliminary phase is usually expensive both in terms of time and cost. The single scan approach allows to drastically reduce deposition time and material usage, as in fact only a stripe per parameters combination is deposited. These specimens can then be investigated, for example in terms of geometrical features (e.g. growth, width) and microstructure to assess the most suitable process window. In this work, Ti-6Al-4V single scans, produced by means of directed energy deposition, corresponding to a total of 50 different parameters combinations, were analyzed, focusing on several geometrical features and relative parameters correlations. Moreover, considering the susceptibility of the material to oxygen pick-up, the necessity of an additional shielding gas system was also evaluated, by comparing the specimens obtained with and without using a supplementary argon flow. A process window, which varies according to the user needs, was found together with a relationship between microstructure and process parameters, in both shielding scenarios. Graphic Abstract


2019 ◽  
Vol 37 (6) ◽  
pp. 579-584
Author(s):  
Desrilia Nursyifaulkhair ◽  
Nokeun Park ◽  
Eung Ryul Baek ◽  
Jong-bong Lee

Author(s):  
Michael Liu ◽  
Mathew Kuttolamadom

Abstract In this study, Co-Cr-Mo samples that were fabricated via directed energy deposition (DED) at various laser powers and powder feed rates were characterized to ascertain their microstructure and mechanical properties. Co-Cr-Mo is a common alloy for total hip and knee replacements, dental, and support structures due to its biocompatibility, hardness and abrasion resistance, making them a preferred alloy for metal-on-metal (MOM) contact. This study was undertaken to understand the pertinent process parameters that would generate structurally viable bulk structures. High-resolution microscopy and spectroscopy revealed the presence of networked and jagged carbides with varying amounts of Mo. Further, XRD confirmed the presence of the γ and ε phases. Micro- and nano-scale characterization of the alloy fabricated at different process conditions showed material properties in line with those made via traditional processing approaches such as casting. Altogether, this investigation provided an understanding of the effect of additive manufacturing process parameters on the microstructure and properties of Co-Cr-Mo.


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