Parametric Study and Multi-Criteria Optimization in Laser Directed Energy Deposition of 316L Stainless Steel

2020 ◽  
Author(s):  
Samuel Kersten ◽  
Maxwell Praniewicz ◽  
Omar Elsayed ◽  
Thomas Kurfess ◽  
Christopher Saldana
Keyword(s):  
Energy Deposition ◽  
Base Material ◽  
Predictive Modelling ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Process Conditions ◽  
Material System ◽  
Multiple Parameters ◽  
Directed Energy Deposition ◽  
Directed Energy

Abstract Directed Energy Deposition (DED) is an additive manufacturing technique in which a heat source is used to generate a small pool of molten material while powder feedstock is fed into the melt pool to create tracks of raised material on the surface of a part. Given the appropriate process parameters for the chosen material system and process conditions, fully dense complex geometric features are able to be constructed. In order to generate a high quality clad, two main criteria must be met: sufficient bonding with the substrate with minimized dilution of the clad by the base material and minimal porosity. Track shape is a key indicator in determining the quality of the process. This paper evaluates the influence of several of the key processing parameters — laser power, scanning speed, and powder mass flowrate — on single-clad track morphology. An analysis of variance (ANOVA) is performed to evaluate the significance of the main input parameters and the interactions between multiple parameters. A second-order polynomial model is then fit to the data to allow for predictive modelling of track shape based on a set of inputs. Finally, a multi-criteria cost function is generated, and sequential quadratic programming is performed to solve the objective function. Through these operations, the correct combination of processing parameters can be selected in order to generate a cladded track with desirable geometric traits.

Discrete Phase Modeling of the Powder Flow Dynamics and the Catchment Efficiency in Laser Directed Energy Deposition with Inclined Coaxial Nozzles

2021 ◽  
pp. 1-37
Author(s):  
Sachin Alya ◽  
Ramesh Singh
Keyword(s):  
Mass Flow ◽  
Energy Deposition ◽  
Flow Dynamics ◽  
Free Form ◽  
Powder Flow ◽  
Process Conditions ◽  
Directed Energy Deposition ◽  
Discrete Phase ◽  
Directed Energy ◽  
Inclined Nozzle

Abstract Laser Directed Energy Deposition (DED) is one of the most promising additive manufacturing processes for restoring high value components. The damaged components can have complex free-form shapes which necessitates depositions with an inclined nozzle, where, the gravity can adversely affect the powder flow dynamics and the powder catchment efficiency (PCE). PCE is defined as the fraction of the total mass flow rate entering the melt pool and a low PCE can render the process inviable. In this paper, the effect of nozzle inclination on the powder flow dynamics and resulting PCEs have been studied. It was found that the powder flow dynamics is altered significantly in an inclined nozzle and results in an asymmetric and skewed powder jet. This affects the powder focusing adversely and the PCE deteriorates rapidly with an increase in the inclination and falls below 20% at 75°. A discrete phase model has been developed to understand the powder flow dynamics at different inclinations and process conditions. The mass flow distribution asymmetry on the focal plane at various nozzle inclinations have been analyzed via the model. The model is able to predict PCEs at different nozzle inclinations with reasonable accuracy. It has been observed that carrier gas flow, particle size and laser diameter affect the PCE significantly and can be used to counter the enhanced powder loss at large nozzle inclinations. Process maps have been developed to identify the favorable, acceptable and low PCE regions for the selection of optimal DED parameters.

scholarly journals Direct Laser Additive Manufacturing of TiAl Intermetallic Compound by Powder Directed Energy Deposition (DED)

2020 ◽  
Vol 321 ◽  
pp. 03020
Author(s):  
Damien Choron ◽  
Serge Naveos ◽  
Marc Thomas ◽  
Johan Petit ◽  
Didier Boisselier
Keyword(s):  
Energy Deposition ◽  
Temperature Cycling ◽  
Temperature Management ◽  
Geometrical Parameters ◽  
Laser Additive Manufacturing ◽  
Multiple Parameters ◽  
Mechanical Characterisation ◽  
Directed Energy Deposition ◽  
Direct Laser ◽  
Directed Energy

Directed Energy Deposition of the commercial intermetallic Ti-48Al-2Cr-2Nb alloy was investigated. The CLAD® process is dependent on multiple parameters, which were successfully optimised through several experiments, including series of beads, small blocks, and massive blocks, under argon atmosphere. The use of adapted temperature management leads to massive blocks manufacturing that bear no apparent macroscopic defects, such as cracks, which are generally observed in this brittle material due to strong temperature cycling during the manufacturing. The microstructure and geometrical parameters were characterised by scanning electron microscopy (SEM). This process generates an ultra-fine and anisotropic microstructure, which is restored to a homogeneous duplex microstructure by a subsequent heat-treatment. Mechanical characterisation is in progress and will be used to validate the soundness of the materials produced in these conditions.

scholarly journals Hybrid Manufacturing: Influence of Directed Energy Deposition Parameters on Microstructure and Layer Adhesion of Stainless Steel 316L

2019 ◽  
Author(s):  
Jakob D. Hamilton ◽  
Samantha Sorondo ◽  
Andrew Greeley ◽  
Bruce E. Kahn ◽  
Patricia Cyr ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Laser Power ◽  
Energy Deposition ◽  
Scanning Speed ◽  
Hybrid Manufacturing ◽  
Stainless Steel 316L ◽  
Directed Energy Deposition ◽  
Deposition Parameters ◽  
Directed Energy

Abstract In-envelope hybrid manufacturing systems comprised of directed energy deposition (DED) and machining provide flexibility for the fabrication of complex geometries with minimal setup changes. However, for these manufacturing set ups, the effects of deposition parameters such as laser power and scanning speed on the quality of the build remain relatively unexplored. An important aspect for developing components with reliable mechanical properties is a thorough understanding of DED thermodynamics during fabrication. Therefore, DED thermodynamics were defined based on the strengthening properties derived from the thermal gradient (G) and solidification rate (R) of the melt pool. Other factors influencing DED thermodynamics include substrate geometry and surface finish which are expected to affect cooling rates and adhesion, respectively. In this work, stainless steel 316L specimens were fabricated varying laser power intensity, scanning speed, and deposition substrate. The effect of these parameters on the microstructure of the sample components were analyzed. Microstructural evolution at various points within and between layers was studied and correlated to localized hardness. An increase in mechanical properties for fine, equiaxed grains demonstrates the Hall-Petch principle for strengthening of components.

Effect of directed energy deposition processing parameters on laser deposited Inconel®718: Microstructure, fusion zone morphology, and hardness

2017 ◽  
Vol 29 (2) ◽  
pp. 022005 ◽  
Author(s):  
Nathan A. Kistler ◽  
Abdalla R. Nassar ◽  
Edward W. Reutzel ◽  
David J. Corbin ◽  
Allison M. Beese
Keyword(s):  
Fusion Zone ◽  
Energy Deposition ◽  
Processing Parameters ◽  
Directed Energy Deposition ◽  
Directed Energy

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.

Laser-assisted directed energy deposition of nickel super alloys: A review

2019 ◽  
Vol 233 (11) ◽  
pp. 2376-2400 ◽  
Author(s):  
AN Jinoop ◽  
CP Paul ◽  
KS Bindra
Keyword(s):  
Energy Deposition ◽  
Processing Parameters ◽  
High Temperature Strength ◽  
Advanced Manufacturing ◽  
Unique Combination ◽  
Laser Additive Manufacturing ◽  
Directed Energy Deposition ◽  
Pure Metals ◽  
Directed Energy ◽  
Reference Document

Laser additive manufacturing using directed energy deposition (LAM-DED) is an advanced manufacturing process widely deployed for fabricating near net-shaped engineering components. LAM-DED has been successfully used for processing wide variety of pure metals and their alloys. The list of these metals and alloys is appending rapidly. Among the various materials successfully deployed for LAM-DED, nickel super alloys are extensively used for various engineering applications due to the unique combination of superior properties, such as high temperature strength, oxidation, corrosion resistance, etc. Recent studies show that LAM-DED built nickel super alloys finds wide applications in aerospace and automotive sector for fabricating engineering components, repairing, remanufacturing, and cladding. Considering the importance of LAM-DED and nickel super alloys, significant amount of work is already reported. This paper presents a comprehensive review on LAM-DED of nickel super alloys. It introduces LAM technology and nickel super alloys with a compilation of various lasers and processing parameters deployed for LAM-DED of nickel super alloys. The paper compiles the metallurgy, mechanical properties, processing issues, and effect of post-processing on LAM-DED built nickel super alloys. This paper will serve as a quick-start for novices to understand LAM-DED of nickel super alloys and will be useful as a reference document for researchers and industrialists in the field.

A model to predict deposition parameters for directed energy deposition: part I theory and modeling

2019 ◽  
Vol 25 (6) ◽  
pp. 998-1006
Author(s):  
Cameron Myron Knapp ◽  
Thomas J. Lienert ◽  
Paul Burgardt ◽  
Patrick Wayne Hochanadel ◽  
Desiderio Kovar
Keyword(s):  
Stainless Steel ◽  
Energy Deposition ◽  
Single Layer ◽  
Processing Parameters ◽  
Physical Models ◽  
Small Range ◽  
Content Type ◽  
Directed Energy Deposition ◽  
Directed Energy ◽  
Type 304

Purpose Directed energy deposition (DED) with laser powder-feed is an additive manufacturing process that is used to produce metallic components by simultaneously providing a supply of energy from a laser and mass from a powder aerosol. The breadth of alloys used in DED is currently limited to a very small range as compared to wrought or cast alloys. The purpose of this paper is to develop the new alloys for DED is limited because current models to predict operational processing parameters are computationally expensive and trial-and-error based experiments are both expensive and time-consuming. Design/methodology/approach In this research, an agile DED model is presented to predict the geometry produced by a single layer deposit. Findings The utility of the model is demonstrated for type 304 L stainless steel and the significance of the predicted deposition regimes is discussed. The proposed model incorporates concepts from heat transfer, welding and laser cladding; and integrates them with experimental fits and physical models that are relevant to DED. Originality/value The utility of the model is demonstrated for type 304 L stainless steel and the significance of the predicted deposition regimes is discussed.

Predicting Part-Level Thermal History in Metal Additive Manufacturing Using Graph Theory: Experimental Validation With Directed Energy Deposition of Titanium Alloy Parts

2019 ◽  
Author(s):  
Reza Yavari ◽  
Jordan Severson ◽  
Aniruddha Gaikwad ◽  
Kevin Cole ◽  
Prahalad Rao
Keyword(s):  
Heat Flux ◽  
Titanium Alloy ◽  
Additive Manufacturing ◽  
Energy Deposition ◽  
Process Conditions ◽  
Theoretic Approach ◽  
Temperature Trends ◽  
Directed Energy Deposition ◽  
Directed Energy ◽  
Metal Additive

Abstract The objective of this paper is to experimentally validate the graph-based approach that was advanced in our previous work for predicting the heat flux in metal additive manufactured parts. We realize this objective in the specific context of the directed energy deposition (DED) additive manufacturing process. Accordingly, titanium alloy (Ti6Al4V) test parts (cubes) measuring 12.7 mm × 12.7 mm × 12.7 mm were deposited using an Optomec hybrid DED system at the University of Nebraska-Lincoln (UNL). A total of six test parts were manufactured under varying process settings of laser power, material flow rate, layer thickness, scan velocity, and dwell time between layers. During the build, the temperature profiles for these test parts were acquired using a single thermocouple affixed to the substrate (also Ti6Al4V). The graph-based approach was tailored to mimic the experimental DED process conditions. The results indicate that the temperature trends predicted from the graph theoretic approach closely match the experimental data; the mean absolute percentage error between the experimental and predicted temperature trends were in the range of 6% ∼ 15%. This work thus lays the foundation for predicting distortion and the microstructure evolved in metal additive manufactured parts as a function of the heat flux. In our forthcoming research we will focus on validating the model in the context of the laser powder bed fusion process.

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